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Nitrogen and phosphorus spatio-temporal distribution and fluxes intensifying eutrophication in three tropical rivers of Côte d'Ivoire (West Africa)

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Nutrient contamination assessments in the three West African tropical Comoé, Bandama, and Bia Rivers (Côte d'Ivoire) were performed from March 2016 to March 2018. Five stations per river were sampled. Nutrients spatio-temporal distributions were mapped and showed nitrogen concentrations (nitrite 0.001 to 0.025 mg/L NO2−-N, and nitrate 0.26 to 3.60 mg/L NO3−-N) increased significantly with rainfall contrary to phosphorus (0.01 to 0.12 mg/L P). The Chl-a and TSItsr data revealed the hypereutrophic status of rivers. Moreover, N:P mass ratio suggests nitrogen as the main limiting factor of primary production during the low (March) and high flow periods (October–November), while phosphorus is the limiting factor in June, at the high flow beginning. The land uses around watersheds were the main sources of phosphorus and nitrogen enhancing the rivers' eutrophication. Phosphorus and nitrogen fluxes were related to leaching river catchments and were significant sources of nutrients to the Atlantic Ocean.
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CORRECTED PROOF
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6Laboratoire de Thermodynamique et de Physico-Chimie du Milieu, UFR-SFA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
7Laboratoire de Constitution et de Réaction de la Matière, Université Felix Houphouët Boigny, 22 BP 582, Abidjan 22, Côte d'Ivoire
8Département de Sciences et Techniques, Université Alassane Ouattara, BP V 18, Bouaké 01, Côte d'Ivoire
9Centre de Recherches Océanologiques, 29, rue des pêcheurs, BP V18, Abidjan, Côte d'Ivoire
:Département de Mathématiques Physique Chimie, Université Peleforo Gon Coulibaly, BP 1328, Korhogo, Côte d'Ivoire
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1. Introduction
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CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
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2. Materials and methods
2.1. Study area
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 B D; 9>;;:G:C8: >C A:K:A ;DG  @B 6GDJC9  B E:G @B /=:
6C96B6 ->K:G 86I8=B:CI 6G:6 8DK:GH  @B6C9 I6@:H >IH HDJG8:
>C I=: CDGI=:GC ^I: 9$KD>G: 7:IL::C &DG=D<D 6C9 DJC9>6A> 6I 6C 6AI>
Fig. 1. .6BEA>C< HI6I>DCH 6ADC< I=: DBDX 6C96B6 6C9 >6 ->K:GH
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
IJ9: D;  B 6C9 ;ADLH HDJI=L6G9  @B 7:;DG: 9>H8=6G<>C< >CID
"G6C9'6=DJ '6<DDC 6C9 I=: "JA; D; "J>C:6 /=: 6CCJ6A 6K:G6<: 9>H
8=6G<: D; I=>H G>K:G >H 67DJI  BH /=: IGDE>86A IG6CH>I>DC6A G:<>B:
D; I=: DBDX 6C9 6C96B6 ->K:GH >H 8=6G68I:G>O:9 7N 6 H>C<A: <G:6I
;ADD9 J<JHI*8ID7:G 6C9 6 ADC< E:G>D9 D; ADL L6I:G %6CJ6GN(6N
!>< .
/=: >6 ->K:G >H 6 HB6AA G>K:G D;  @B >C A:C<I= L>I= 6C 6CCJ6A
;ADL D;  BH AD86I:9 >C I=: HDJI=:6HI 8DGC:G D; ^I: 9$KD>G: 6C9
;ADLH HDJI=L6G9 ID 9>H8=6G<: >CID 7N '6<DDC ADC< >IH L6I:GH=:9 I=:
:FJ6IDG>6A IG6CH>I>DC G:<>B: >H 8=6G68I:G>O:9 7N ILD 6CCJ6A ;ADD9H /=:
;>GHI DC: JHJ6AAN I=: HIGDC<:HI D88JGH >C I=: %JC:%JAN E:G>D9 6C9 I=:
H:8DC9 DC: HEG:69H ;GDB *8ID7:G ID )DK:B7:G ADL L6I:G E:G>D9 >H
D7H:GK:9 >C J<JHI.:EI:B7:G 6C9 6CDI=:G BJ8= BDG: B6G@:9 :M
I:C9H ;GDB :8:B7:G ID (6G8= JG6C9 :I 6A ">G6G9 :I 6A
 /=: I=G:: G>K:G L6I:GH=:9H 6G: HJ7?:8I ID ;DJG 8A>B6I>8 H:6HDCH
6BDC< L=>8= L: =6K: 6 ADC< 9GN H:6HDC :8:B7:G(6G8= 6 ADC<
G6>CN H:6HDC EG>A%JAN 6 H=DGI 9GN H:6HDC J<JHIB>99A: .:EI:B
7:G 6C9 6 H=DGI G6>CN H:6HDC (>99A: .:EI:B7:G)DK:B7:G
2.2. Monitoring and sampling strategy
.>M H6BEA>C< 86BE6><CH >C I=: DBDX 6C96B6 6C9 >6 ->K:GH
L:G: 86GG>:9 DJI >C (6G8= %JC: 6C9 *8ID7:G  >C %JC: 6C9 )D
K:B7:G  6C9 >C (6G8=  9JG>C< I=: 9GN G6>CN 6C9 ;ADD9 H:6
HDCH /67A: H=DLH BDC>IDG>C< HI6I>DCH <:D<G6E=>8 8DDG9>C6I:H 6C9
A6C9 JH: 6GDJC9 I=: G>K:G 76H>CH /=: HI6I>DCH 9>HIG>7JI>DC DC I=: G>K:GH
;DAADLH 6 HIG6I:<N 6>B:9 6I 6 7:II:G JC9:GHI6C9>C< D; I=: :JIGDE=>86I>DC
E=:CDB:CDC >C I=: 9>;;:G:CI HIG:6BH /LD HI6I>DCH ** JE
HIG:6B DC I=: DBDX ->K:G 8=6G68I:G>O:9 I=: L6I:G HI6I: JEHIG:6B DC:
HI6I>DC * >C I=: 8>IN 8:CI:G D; AXEX 6>B:9 6I =><=A><=I>C< I=: >BE68I
D; I=: 8>IN 6C9 I=: A6HI HI6I>DCH ** L:G: EA68:9 9DLCHIG:6B ID
6HH:HH I=: >BE68I D; I=>H G>K:G DC :HIJ6G>C: L6I:GH R7G>X A6<DDC
/=: 26I:GH=:9 A6C9 JH: >BE68I JEHIG:6B D; I=: 6C96B6 ->K:G L6H
6HH:HH:9 L>I= ILD HI6I>DCH *C: AD86I:9 DC I=: L:HI:GC 7G6C8= D; I=:
G>K:G 69?D>C>C< 6 A6G<: 6<GDE6HIDG6A ;6GB L6H  6C9 I=: DI=:G DC:
Table 1
.6BEA>C< HI6I>DCH <:D<G6E=>8 8DDG9>C6I:H 6C9 A6C9 JH:
->K:G .I6I>DCH 'D86A>I>:H
8>I>:H
DDG9>C6I:H '6C9 JH:
Comoé * C>6HHJX  )
 2
!6GB>C<8686DGJ77:G
* (6CO6C  )
 2
686DGJ77:G;DD9 8GDEH
* A:E:  )
 2
0G76C
* DCDJ6  )
 2
0G76C AJB7:GB>AA
* 6HH6B  )
 2
0G76C ;DG:HI 6C9 L:IA6C9H
Bandama  6;X86D  )
 2
!6GB>C<E6HIJG: 8686D
GJ77:G
 )O>  )
 2
0G76C 6<GDE6HIDG6A ;6GB
 />6HH6AX  )
 2
0G76C 6<GDE6HIDG6A ;6GB
 '6=DJ  )
 2
!DG:HI E6AB <GDK:GJ77:G
 G6;;:9DC  )
 2
!DG:HIG:H:GK:
Bia $ >6CDJ6  )
 2
686DGJ77:G B>C>C<
$ N6BX  )
 2
0G76C96B G:H:GKD>G
$ 7D>HHD  )
 2
0G76C
$ &G>C9?67D  )
 2
!DG:HI E6AB <GDK:GJ77:G
$ /=DB6C9>X  )
 2
0G76C ;6GB>C<
 6I I=: :6HI:GC L6H AD86I:9 DC I=: B6>C IG>7JI6GN D; I=: )O> ->K:G
.I6I>DC  L6H AD86I:9 >C I=: 8:CI:G D; I=: 8>IN />6HH6AX ID 9:I:GB>C:
I=: 8DB7>C:9 >BE68I D; I=: 8>IN 6C9 I=: B>M>C< L6I:GH ;GDB I=: 8DC;AJ
:C8: 7:IL::C I=: ILD 7G6C8=:H 6C96B6 ->K:G)O> >C I=: CDGI= /=:
A6HI HI6I>DCH  L:G: AD86I:9 >C I=: 6C96B6 ->K:G :HIJ6GN ID
6HH:HH I=: >BE68I D; I=: :M8=6C<>C< G>K:G L6I:G B6HH:H L>I= I=: "G6C9
'6=DJ '6<DDC
/=: N6BX 96B 6C9 >IH G:H:GKD>G =6K: 6 HIGDC< >BE68I DC I=: >6
->K:G =N9GDAD<N 6C9 86C EA6N 6 <G:6I GDA: >C G:<JA6I>C< ;ADLH /=JH I=:
JEHIG:6B HI6I>DC D; N6BX 96B $ I=: 96B G:H:GKD>G $ 6C9 I=:
9DLCHIG:6B HI6I>DC D; I=: 96B  L:G: 8=DH:C ID HIJ9N I=:H: 8DB
7>C:9 :;;:8IH !>C6AAN I=: HI6I>DCH $$ B69: >I EDHH>7A: ID JC
9:GHI6C9 I=: JG76C >BE68I D; 7D>HHD 8>IN 6C9 I=: G>K:G :M8=6C<:H L>I=
I=: 7N '6<DDC 6I I=: :HIJ6GN "+. L6H JH:9 ID B6G@ I=: ADC<>IJ9:
6C9 A6I>IJ9: K6AJ:H D; :68= HI6I>DC L>I= C:<6I>K: K6AJ:H L:HIL6G9 6C9
EDH>I>K: CDGI=L6G9 /67A: 
/=: L6I:G H6BEA>C< L6H 86GG>:9 DJI 688DG9>C< ID I=: G:;:G:C8:
B:I=D9H ;DG H6BEA>C< >C 8DCI>C:CI6A :CK>GDCB:CIH -D9>:G :I 6A
 !DG :68= H6BEA: HJG;68: L6I:G  8B 7:ADL I=: HJG;68: L6H
I6@:C 7N JH>C< 6  ' )>H@>C 7DIIA: >C I=: B>99A: D; I=: G>K:G ;GDB 6 86
CD: $BB:9>6I: B:6HJG:B:CIH D; E=NH>8D8=:B>86A E6G6B:I:GH L:G: G:
6A>O:9 JH>C< 6 BJAI>E6G6B:I:G #)) #$  :< I:BE:G6IJG:
E# :A:8IG>86A 8DC9J8I>K>IN H6A>C>IN 9>HHDAK:9 DMN<:C 8DC8:CIG6I>DC
6C9 IDI6A 9>HHDAK:9 HDA>9H 26I:G H6BEA:H ;DG CJIG>:CI 6C9 8=ADGDE=NAAa
6C6ANH>H L:G: 8DAA:8I:9 >C I=G:: 7DIIA:H ILD EDAN:I=NA:C: 6C9 DC: 6B
7:G INE: HIDG:9 >C >8: 6I ` 6C9 IG6CHEDGI:9 ID I=: A67DG6IDGN ;DG
6C6ANH:H  =
2.3. Procedure, reagents, and quality assurance
)JIG>:CIH 6C9 8=ADGDE=NAAaL:G: 6C6ANO:9 >C I=: '67DG6IDGN D; :C
IG: .J>HH: 9: -:8=:G8=:H .8>:CI>;>FJ:H .-. D; 9>DED9DJBX 7>9
?6C 6H E:G I=: B:I=D9DAD<>:H G:8DBB:C9:9 7N I=: HI6C96G9 B:I=D9H
;DG ;G:H=L6I:G 6C9 L6HI:L6I:G :M6B>C6I>DC -D9>:G :I 6A ->8: :I
6A  .6BEA:H L:G: ;>AI:G:9 I=GDJ<= 6 2=6IB6C "!! ;>AI:G EDGDH
>IN  μB ;DG 6C6ANH>H D; 9>HHDAK:9 CJIG>:CIH 6C9 8=ADGDE=NAAa
EDGI67A: HE:8IGDE=DIDB:I:G ## BD9:A - L6H JH:9 ;DG
6C6ANH>H /6G6;9:G 6C9 -6I=DG:  "G>:HH G:68I>DC ;DG C>IG>I: >DCH
&DGDA:;;  ;DG 6BBDC>JB >DCH B:6HJG:B:CIH "G6HH=D;; :I 6A
 ;DG C>IG6I: >DCH 6C9 (JGE=N 6C9 ->A:N  ;DG G:68I>K: E=DH
E=DGJH =ADGDE=NAAaL6H :MIG68I:9 L>I= 68:IDC:   >C I=: 96G@
;DAADL:9 7N 6 HE:8IGDE=DIDB:IGN B:6HJG:B:CI 6I  6C9  CB 67
HDG76C8: 'DG:CO:C 
0C;>AI:G:9 L6I:G H6BEA:H L:G: JH:9 ID B:6HJG: /DI6A + 6C9 /DI6A )
!DG /DI6A + 9:I:GB>C6I>DC  B' D; I=: L6I:G H6BEA: >H ;>GHI 9><:HI:9
L>I= 8DC8:CIG6I:9 HJA;JG>8 6C9 C>IG>8 68>9H -:68I>K: E=DHE=DGJH
+* B:6HJG:B:CI >C I=: 9><:HI:9 H6BEA: >H 9DC: 688DG9>C< ID I=:
(JGE=N 6C9 ->A:N 8DADG>B:IG>8 B:I=D9  !DG /DI6A &?:A96=A ) 9:
I:GB>C6I>DC &?:A96=A   B' D; I=: L6I:G H6BEA: >H ;>GHI 9>
<:HI:9 L>I=  B' D; 8DC8:CIG6I:9 HJA;JG>8 68>9 6C9 < D; H:A:C>JB 86I
6ANHI /=: HDAJI>DC >H I=:C 9>HI>AA:9 L>I=  B' D; HD9>JB =N9GDM>9:
  >C 6C 6JIDB6I>8 &?:A96=A 9>HI>AA6I>DC JC>I 0&  1 '+a .$
)/$!$ /=: 9>HI>AA6I: >H ;>C6AAN I>IG6I:9 L>I= 6 =N9GD8=ADG>8 68>9 HD
AJI>DC  ) .6BEA:H 9><:HI>DC :< /DI6A + 6C9 /DI6A &?:A96=A )
L6H E:G;DGB:9 L>I= 6C 6JIDB6I>8 &?:A96=A 9><:HI>DC JC>I &' .:G>:H
1 '+a .$ )/$!$
/DI6A ) L6H D7I6>C:9 7N HJBB6I>DC D; I=: /DI6A &?:A96=A ) 6C9 I=:
DM>9:9 ) ;DGBH A6C@H L:G: 6C6ANO:9 >C :68= 76I8= D; L6I:G H6BEA:H
I=GDJ<=DJI I=: :CI>G: 6C6ANI>86A EGD8:9JG: /=: 688JG68N 6C9 EG:8>H>DC
D; I=: G:HJAIH L:G: 8=:8@:9 7N IG>EA>86I: B:6HJG:B:CIH /=: 9:I:8I>DC
A>B>IH L:G:  B<' ;DG +*  B<' ;DG )#  B<'
;DG )*6C9  μ<' ;DG =Aa /=: :GGDGH >C 6C6ANH:H >C I:GBH D; HI6C
96G9 9:K>6I>DCH D; IG>EA>86I: H6BEA:H L:G: ;DJC9 ID 7:  
 B<' 6C9  μ<' ;DG +* )# )* 6C9 =Aa G:HE:8
I>K:AN
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
2.4. Eutrophication assessment
/=: IGDE=>8 HI6IJH D; I=: DBDX 6C96B6 6C9 >6 ->K:GH L6H 6H
H:HH:9 JH>C< ILD IDDAH I=: 8A6HH>;>86I>DC H8=:B: ;DG =Aa7>DB6HH D;
I=: JGDE:6C CK>GDCB:CI6A <:C8N :JIGDE=>86I>DC G:EDGI  
#JD :I 6A  6C9 I=: IGDE=>8 HI6I: >C9:M ;DG IGDE>86AHJ7IGDE>86A
G:H:GKD>GH /.$IHG JC=6 :I 6A 6 /67A: 8A6HH>;>:H I=: L6I:G FJ6A
>IN 688DG9>C< ID I=: A:K:A D; :JIGDE=>86I>DC /=: 8A6HH>;>86I>DC G6C<:H <D
;GDB L6I:G D; :M8:AA:CI FJ6A>IN >: DA><DIGDE=>8 ID EDDG 6C9 9:<G69:9
L6I:G >: =NE:G:JIGDE=>8 6;;:8I>C< ;DG I=: A6II:G I=: 6FJ6I>8 :8DHNH
I:B 6C9 86C 86JH: 6 EJ7A>8 =:6AI= EGD7A:B
2.4.1. Chl-a biomass classification scheme
/=: 8A6HH>;>86I>DC H8=:B: ;DG =Aa7>DB6HH :HI67A>H=:9 688DG9>C< ID
I=: >CI:GC6I>DC6AAN 688:EI:9 :JIGDE=>86I>DC H86A: >H 76H:9 DC =Aa8DC
8:CIG6I>DC  #JD :I 6A %>C 6C9 /J  /=: =Aa
8DC8:CIG6I>DCH 6G: 8A6HH>;>:9 >CID H>M <G69:H  μ<' G:EG:H:CI>C<
DA><DIGDE=>8  μ<' B:HDIGDE=>8  μ<' A><=I:JIGDE=>8
 μ<' B>9:JIGDE=>8  μ<' =><=:JIGDE=>8 6C9
 μ<' =NE:G:JIGDE=>8 /67A: 
2.4.2. The trophic state index TSItsr
/=: 6CCJ6A IGDE=>8 HI6IJH D; 6AA H>I:H L6H 6AHD 6HH:HH:9 76H:9 DC I=:
:MEG:HH>DCH D; /.$IHG :HI67A>H=:9 7N JC=6 :I 6A 6

L=:G:


L>I= 6CCJ6A <:DB:IG>8 B:6C "B:6C 8DC8:CIG6I>DCH D; /+ 6C9
=Aaμ<'
/67A: H=DLH I=: 9>;;:G:CI IDDAH JH:9 ;DG I=: :JIGDE=>86I>DC 6HH:HH
B:CI I=: 8A6HH:H D; :JIGDE=>86I>DC HI6IJH 6C9 I=: :JIGDE=>86I>DC
G6C<:
2.5. Water quality assessment in rivers
2.5.1. The CONAMA classification for the freshwater quality
26I:G FJ6A>IN 9:E:C9H DC >IH JH:H HJ8= 6H 9G>C@>C< L6I:G EGD9J8
I>DC L6I:G>C< 6FJ68JAIJG: >GG><6I>DC G:8G:6I>DC C6K><6I>DC 6C9
A6C9H86E: "DD9 FJ6A>IN L6I:G 9D:H CDI 6;;:8I I=: 6FJ6I>8 :8DHNHI:B DG
=JB6C JH: DG 6C>B6A 8DCHJBEI>DC GJO :I 6A  /D 6HH:HH I=: :C
K>GDCB:CI6A FJ6A>IN D; I=: G>K:GH L6I:G >C I=: EG:H:CI HIJ9N I=: B6M>
BJB 6AADL67A: 8DC8:CIG6I>DC A>B>IH ('H :HI67A>H=:9 ;DG 9>;;:G:CI
Table 2
(:I=D9DAD<>86A IDDAH 6C9 G6C<:H JH:9 ;DG I=: :JIGDE=>86I>DC 6HH:HHB:CI D;
I=: G>K:GH
=Aa6/.$IHG7.I6I: D; L6I:G
FJ6A>IN
':K:A D;
:JIGDE=>86I>DC
/GDE=>8 HI6I:
  #><= 'DL *A><DIGDE=>8
 

"DD9 (:9>JB (:HDIGDE=>8
 

(D9:G6I: #><= '><=I:JIGDE=>8
 (>9:JIGDE=>8




+DDG 6C9 9:<G69:9 A:K6I:9 #><=:JIGDE=>8
  #NE:G:JIGDE=>8
G>I=B:I>8 B:6C μ<'
6 #JD :I 6A %>C 6C9 /J 
7JC=6 :I 6A 6
8A6HH:H D; JH: 7N I=: G6O>A>6C )6I>DC6A CK>GDCB:CI6A DJC8>A
*)( -:HDAJI>DC  JC=6 :I 6A 7GJO :I 6A
 ;DG ;G:H=L6I:G 7D9>:H L:G: 69DEI:9 ->K:G L6I:GH 86C 7: <GDJE:9
>CID ;DJG 8A6HH:H  ID  /=: ;>GHI I=G:: 8A6HH:H D; L6I:G 6G: 8DCH>9:G:9
6EEGDEG>6I: ;DG =JB6C 8DCHJBEI>DC 7JI G:FJ>G: K6GN>C< 9:<G::H D;
IG:6IB:CI ;GDB 6ABDHI CDC: ID 69K6C8:9 IG:6IB:CI 26I:GH D; 8A6HH
6G: 8DCH>9:G:9 HJ>I67A: DCAN ;DG C6K><6I>DC 6C9 A6C9H86E: JH:H $I
H=DJA9 7: :BE=6H>O:9 I=6I I=: ^I: 9$KD>G: ->K:GH 9D:H CDI N:I =6K: 6
L6I:G JH: 9>G:8I>K: /=JH >I L6H 9:8>9:9 ID :K6AJ6I: :68= G>K:G 688DG9
>C< ID I=: ('H K6AJ:H ;DG ;G:H=L6I:G 8A6HH:H A6HH  A6HH  6C9
A6HH  :HI67A>H=:9 7N I=: *)( -:HDAJI>DC  /67A: .
2.5.2. The water quality indices (WQI)
/=: JH: D; L6I:G FJ6A>IN >C9>8:H 2,$ >H 6 H>BEA: EG68I>8: I=6I DK:G
8DB:H B6CN EGD7A:BH 6C9 6AADLH I=: EJ7A>8 6C9 9:8>H>DCB6@:GH ID G:
8:>K: L6I:G FJ6A>IN >C;DGB6I>DC /=: 2,$ 6AHD 6HH:HH:H 8=6C<:H >C I=:
FJ6A>IN D; HJG;68: L6I:G (DH8JOO6 :I 6A 
/=: 2,$ 86A8JA6I>DCH JH:9 =:G: L:G: EGDEDH:9 7N +:H8: 6C9
2JC9:GA>C 

L=:G: C >H I=: IDI6A CJB7:G D; E6G6B:I:GH >C8AJ9:9 >C I=: HIJ9N >
>H I=: CDGB6A>O:9 K6AJ: D; E6G6B:I:G > 6C9 +> >H I=: L:><=I D; E6G6B:
I:G > /67A: .
/=: 2,$ G6C<:H ;GDB ID  L>I= =><= K6AJ:H G:EG:H:CI>C< <DD9
L6I:G FJ6A>IN 8DC9>I>DCH /=: L6I:G FJ6A>IN L6H 8A6HH>;>:9 >CID ;>K:
<G69:H 76H:9 DC I=: 2,$ H8DG:H :M8:AA:CI  <DD9 
BD9:G6I:  ADL  6C9 769  2J :I 6A 
/=: 2,$ K6AJ: D; :68= H6BEA>C< HI6I>DC L6H 86A8JA6I:9 DC 6 H:6
HDC6A 76H>H
2.6. Analyses and treatment of data
C6ANH>H D; K6G>6C8: )*1 L6H E:G;DGB:9 ID 6H8:GI6>C H:6HDC6A
6C9 HE6I>6A 9>;;:G:C8:H /=: &GJH@6A26AA>H *C: 26N C6ANH>H D; 16G>
6C8: DC -6C@H L6H E:G;DGB:9 L=:C I=: :FJ6A K6G>6C8: I:HI ;6>A:9 /=:
688:EI67A: A:K:A D; HI6I>HI>86A H><C>;>86C8: L6H 
/=: HE6I>6A 6C9 I:BEDG6A 9>HIG>7JI>DCH D; I=: G:68I>K: E=DHE=DGJH
6C9 C>IG6I:H L:G: :M6B>C:9 I=GDJ<= B6EH 8DBEJI:9 JH>C< I=: G8"$.
G8(6E :CK>GDCB:CI 76H:9 DC I=: $CK:GH: >HI6C8: 2:><=I>C< 6C9
&G><>C< B:I=D9H D; HE6I>6A >CI:GEDA6I>DC 6G 6C9 A>C: <G6E=H L:G: <:C
:G6I:9 JH>C< .><B6EADIa HD;IL6G: K:GH>DC  L>I= 9GN G6>CN 6C9
;ADD9 H:6HDCH G:HJAIH E:G BDC>IDG>C< ED>CI 6C9 I=: HI6C96G9 :GGDG D; I=:
B:6C ;DG C>IG>I:H 6BBDC>JB 8=ADGDE=NAAa, 6C9 I=: /GDE=>8 .I6I: $C
9:M /.$IHG
+:6GHDCH 8DGG:A6I>DC D; I=: L6I:G FJ6A>IN 96I6 6C9 8A>B6I>8 K6G>
67A:H L6H E:G;DGB:9 >C .><B6EADIa HD;IL6G: K:GH>DC  L>I= 6 H><
C>;>86C8: D; 
/=: EG>C8>E6A 8DBEDC:CIH 6C6ANH>H + 6C9 8AJHI:GH L:G: 6AHD
JH:9 ID 6C6ANO: I=: ;68IDGH >C;AJ:C8>C< CJIG>:CI AD69H 6C9 I=: HDJG8:H D;
CJIG>:CI >CEJIH .I6I>HI>86a K:GH>DC  L6H JH:9 ID <:C:G6I: L:><=IH
6C9 H8DG:H
3. Results
3.1. Physico-chemical parameters
/=: L6I:G I:BE:G6IJG: G6C<: L6H  ` L>I= 6C 6K:G6<:
K6AJ: D;  d  ` >C I=: DBDX ->K:G  ` L>I= 6C 6K
:G6<: K6AJ: D;  d  ` >C I=: 6C96B6 ->K:G 6C9  `
L>I= 6C 6K:G6<: K6AJ: D;  d  ` >C I=: >6 ->K:G !>< 6 JG
>C< I=: 9GN H:6HDC I=: L6I:G I:BE:G6IJG: H=DL:9 H><C>;>86CIAN =><=:G
K6AJ:H I=6C I=: G6>CN 6C9 ;ADD9 H:6HDCH p  /67A:  /=: =><=
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
Fig. 2. .:6HDC6A K6G>6I>DCH D; 6 I:BE:G6IJG: ` 7 E# 8 :A:8IG>86A 8DC9J8I>K>IN μ.8B 9 9>HHDAK:9 DMN<:C B<' : IDI6A 9>HHDAK:9 HDA>9H B<' 6C9 ;
H6A>C>IN EHJ >C I=: DBDX 6C96B6 6C9 >6 ->K:GH 9JG>C< (6G8=  ID (6G8=  E:G>D9H "G6N 8DADG EG:H:CIH I=: 9GN H:6HDCH L=>I: 8DADG EG:H:CIH I=: G6>CN
H:6HDCH 6C9 7A68@ 8DADG EG:H:CIH I=: ;ADD9 H:6HDCH
:HI K6AJ: D7H:GK:9 L6H  ` >C I=: 6C96B6 ->K:G 9JG>C< I=: 
9GN H:6HDC !>< 6 (DG:DK:G L6I:G I:BE:G6IJG: K6G>:9 H><C>;>86CIAN
7:IL::C HI6I>DCH * 6C9 * >C I=: DBDX ->K:G 6C9 HI6I>DCH $
6C9 $ >C I=: >6 ->K:G p  /67A: . /=: L6I:G E# K6AJ:H
K6G>:9 7:IL::C  6C9  L>I= 6C 6K:G6<: K6AJ: D;  d  >C I=:
DBDX ->K:G 7:IL::C  6C9  L>I= 6C 6K:G6<: K6AJ: D;  d 
>C I=: 6C96B6 ->K:G 6C9 7:IL::C  6C9  L>I= 6C 6K:G6<: K6AJ:
D;  d  >C I=: >6 ->K:G !>< 7 /=: G>K:G E# H=DL:9 ADL ;AJ8IJ
6I>DCH DK:G I=: I=G:: H:6HDCH >C I=: 6C96B6 6C9 >6 ->K:GH $C 8DC
IG6HI I=: L6I:G E# >C8G:6H:9 H><C>;>86CIAN 9JG>C< I=: G6>CN H:6HDCH >C
I=: DBDX ->K:G p  /67A: 6C9 !>< 7 26I:G E# L6H 6AHD
H><C>;>86CIAN ADL 6I I=: JEHIG:6B HI6I>DC D; I=: >6 ->K:G $ I=6C 6I
I=: DI=:G HI6I>DCH p  /67A: . H ;DG I=: 6C96B6 ->K:G I=:
L6I:G E# L6H H><C>;>86CIAN =><=:G DC 6K:G6<: 6I I=: JG76C HI6I>DC
 8DBE6G:9 ID I=: JEHIG:6B  6C9 I=: BDJI=  HI6I>DCH
p  /67A: .
A:8IG>86A 8DC9J8I>K>IN   K6AJ:H K6G>:9 7:IL::C  6C9
 μ.8B L>I= 6C 6K:G6<: K6AJ: D;  d  μ.8B >C I=: D
BDX ->K:G 7:IL::C  6C9  μ.8B L>I= 6C 6K:G6<: K6AJ: D;
 d  μ.8B >C I=: 6C96B6 ->K:G 6C9 7:IL::C  6C9
 μ.8B L>I= 6C 6K:G6<: K6AJ: D;  d  μ.8B >C I=: >6
->K:G !>< 8 JG>C< I=: 9GN H:6HDCH H=DL:9 H><C>;>86CIAN =><=:G
K6AJ:H I=6C I=: G6>CN 6C9 ;ADD9 H:6HDCH >C I=: DBDX 6C9 I=: >6 ->K:GH
p  /67A:  $C 8DCIG6HI H=DL:9 ADL ;AJ8IJ6I>DCH DK:G I=:
I=G:: H:6HDCH >C I=: 6C96B6 ->K:G (DG:DK:G K6G>:9 H><C>;>86CIAN
7:IL::C I=: JEHIG:6B HI6I>DC  6C9 I=: BDJI= DC:  D; I=:
6C96B6 ->K:G /=: =><=:HI K6AJ:H D7H:GK:9 L:G:  μ.
8B 6I I=: BDJI= D; I=: 6C96B6 ->K:G 9JG>C< I=: G6>CN H:6HDCH !><
8 p  /67A: .
/=: L6I:G 9>HHDAK:9 DMN<:C * 8DC8:CIG6I>DC G6C<:H L:G:
 B<' L>I= 6C 6K:G6<: K6AJ: D;  d  B<' >C I=: DBDX
->K:G  B<' L>I= 6C 6K:G6<: K6AJ: D;  d  B<' >C I=:
6C96B6 ->K:G 6C9  B<' L>I= 6C 6K:G6<: K6AJ: D;
 d  B<' >C I=: >6 ->K:G !>< 9 * H=DL:9 ADL ;AJ8IJ6I>DCH
DK:G I=: I=G:: H:6HDCH >C I=: 6C96B6 6C9 >6 ->K:GH $C 8DCIG6HI *
:K>9:C8:9 6 H><C>;>86CI 9GDE 9JG>C< I=: 9GN H:6HDCH >C I=: DBDX ->K:G
p  /67A: 6C9 !>< 9 (DG:DK:G * L6H 6AHD H><C>;>86CIAN
=><=:G DC 6K:G6<: 6I I=: JEHIG:6B HI6I>DC  I=: 6<GDE6HIDG6A HI6I>DC
>C I=: 6C96B6 ->K:G I=6C 6I I=: DI=:G HI6I>DCH p  /67A: .
/. 8DC8:CIG6I>DCH H=DL:9 H><C>;>86CI H:6HDC6A K6G>6I>DCH >C I=:
DBDX 6C9 >6 ->K:GH p  /67A: 6C9 !>< : 6C9 G:68=:9
I=:>G =><=:HI K6AJ:H 9JG>C< I=: 9GN H:6HDC 6I JEHIG:6B HI6I>DCH *
 B<' >C I=: DBDX ->K:G 6C9 $  B<' >C I=: >6 ->K:G
#DL:K:G I=: B:6C /. K6AJ: 6I I=: 6C96B6 ->K:G BDJI=
 d  B<' HI6I>DC  9JG>C< I=: G6>CN H:6HDC L6H =><=:G
I=6C 6I I=: DI=:G HI6I>DCH !DG H6A>C>IN K6AJ:H L:G: 6ABDHI O:GD >C 6AA
G>K:GH 6AI=DJ<= H:6HDC6A ;AJ8IJ6I>DCH L:G: D7H:GK:9 >C I=: 6C96B6
->K:G 6 E:6@ K6AJ: D;  EHJ L6H D7H:GK:9 >C I=: 6C96B6 ->K:G 9JG
>C< I=:  G6>CN H:6HDC !>< ;
3.2. Nutrients and chlorophyll-a
3.2.1. Dissolved nutrients
-:68I>K: E=DHE=DGJH +* 8DC8:CIG6I>DCH G6C<:H L:G:
 B<' + L>I= 6C 6K:G6<: K6AJ: D;  d  B<' +
>C I=: DBDX ->K:G  B<' + L>I= 6C 6K:G6<: K6AJ: D;
 d  B<' + >C I=: 6C96B6 ->K:G 6C9  B<'
+ L>I= 6C 6K:G6<: K6AJ: D;  d  B<' + >C I=: >6 ->K:G
!>< 
+*H=DL:9 H><C>;>86CIAN =><=:G K6AJ:H 9JG>C< I=: 9GN 6C9 ;ADD9
H:6HDCH I=6C I=: G6>CN H:6HDC >C I=: DBDX 6C9 >6 ->K:GH p 
/67A:  /=: =><=:HI K6AJ: D7H:GK:9 L6H  B<' + 6I HI6I>DC *
AD86I:9 >C A:E: 8>IN >C I=: DBDX ->K:G 9JG>C< I=: 9GN H:6HDC !>< 
6C9  B<' + 6I HI6I>DC $ 8ADH: ID I=: K>AA6<:&G>C9?67D >C I=:
>6 ->K:G 9JG>C< I=: 9GN H:6HDC !><  H ;DG I=: 6C96B6 ->K:G
+*8DC8:CIG6I>DCH ;AJ8IJ6I:9 HA><=IAN L>I= CD :K>9:CI H:6HDC6A>IN
)*8DC8:CIG6I>DCH !>< EG:H:CI:9 BJ8= ;AJ8IJ6I>DC >C I=:
I=G:: G>K:GH ;GDB  ID  B<' )*) >C I=: DBDX ->K:G ;GDB
 ID  B<' )*) >C I=: 6C96B6 ->K:G 6C9 ;GDB  ID
 B<' )*) >C I=: >6 ->K:G L>I= CD :K>9:CI H:6HDC6A>IN
p  /67A: 6C9 !><  K:G6<: )*8DC8:CIG6I>DCH L:G:
=><=:G 9JG>C< I=: 9GN H:6HDC >C I=: DBDX 6C9 >6 ->K:GH
 d  B<' )*) >C I=: DBDX ->K:G 6C9
 d  B<' )*) >C I=: >6 ->K:G /67A:  6C9 9JG>C< I=:
G6>CN H:6HDC >C I=: 6C96B6 ->K:G  d  B<' )*) /67A:

K:G6<: )*8DC8:CIG6I>DCH L:G: H><C>;>86CIAN =><=:G 9JG>C< I=:
G6>CN H:6HDC I=6C I=: ;ADD9 H:6HDC >C I=: I=G:: G>K:GH
 d  B<' )*) >C I=: DBDX ->K:G  d  B<
' )*) >C I=: 6C96B6 ->K:G 6C9  d  B<' )*) >C
I=: >6 ->K:G 9JG>C< I=: G6>CN H:6HDCH p  /67A:  (DG:DK:G
)*8DC8:CIG6I>DCH EG:H:CI:9 ADL ;AJ8IJ6I>DCH >C I=: I=G:: G>K:GH 9JG
>C< I=: 9GN 6C9 G6>CN H:6HDCH !>< 6
)#8DC8:CIG6I>DCH G6C<:9 ;GDB  ID  B<' )#) >C I=:
DBDX ->K:G ;GDB  ID  B<' )#) >C I=: 6C96B6 ->K:G
6C9 ;GDB  ID  B<' )#) >C I=: >6 ->K:G !>< 7 K:G6<:
)#8DC8:CIG6I>DCH EG:H:CI:9 H><C>;>86CI G>H: 9JG>C< I=: G6>CN H:6HDC
>C I=: DBDX ->K:G  d  B<' )#) p  /67A:  6C9
9JG>C< I=: 9GN H:6HDC >C I=: >6 ->K:G  d  B<' )#)
p  /67A:  $C 8DCIG6HI )#9>9 CDI EG:H:CI HE:8>;>8 H:6HDC6A
K6G>6I>DCH >C I=: 6C96B6 ->K:G p  /67A: 
3.2.2. Chlorophyll-a and total nutrients
=ADGDE=NAAa=Aa 8DC8:CIG6I>DCH G6C<:9 ;GDB  ID  μ<
' L>I= 6C 6K:G6<: K6AJ: D;  d  μ<' >C I=: DBDX ->K:G ;GDB
 ID  μ<' L>I= 6C 6K:G6<: K6AJ: D;  d  μ<' >C I=: 6C
96B6 ->K:G 6C9 ;GDB  ID  μ<' L>I= 6C 6K:G6<: K6AJ: D;
 d  μ<' >C I=: >6 ->K:G !>< 8 =Aa8DC8:CIG6I>DCH 9>9
CDI EG:H:CI HE:8>;>8 H:6HDC6A K6G>6I>DCH 6I 6CN D; I=: I=G:: G>K:GH
p  /67A: 
K:G6<: IDI6A + 8DC8:CIG6I>DCH L:G: 9G6B6I>86AAN =><= >C I=: I=G::
G>K:GH   B<' + /67A:  6C9 L:G: L>I=>C I=: G6C<: D; I=: =N
E:G:JIGDE=>8 G>K:GH 688DG9>C< ID )_GC7:G<  6C9 *  
IGDE=>8 8A6HH>;>86I>DC HNHI:BH /DI6A + 8DC8:CIG6I>DCH 9>9 CDI EG:H:CI
HE:8>;>8 H:6HDC6A K6G>6I>DCH >C I=: DBDX 6C9 >6 ->K:GH p 
/67A:  !DG I=: 6C96B6 ->K:G IDI6A + L6H H><C>;>86CIAN =><=:G 9JG>C<
I=: 9GN H:6HDC I=6C I=: ;ADD9 DC: p  /67A: 
K:G6<: IDI6A ) 8DC8:CIG6I>DCH L:G: 9G6B6I>86AAN =><= >C I=: D
BDX ->K:G 6C9 DCAN 9JG>C< I=: 9GN 6C9 G6>CN H:6HDCH >C I=: 6C96B6
6C9 >6 ->K:GH  B<' ) /67A: L>I=>C I=: G6C<: D; I=: =NE:G
:JIGDE=>8 G>K:GH 688DG9>C< ID I=: )_GC7:G<  IGDE=>8 8A6HH>;>86
I>DC ):K:GI=:A:HH IDI6A ) 8DC8:CIG6I>DCH 9JG>C< I=: ;ADD9 H:6HDC G:
B6>C:9 =><=  B<' ) 6C9 8DC;>GB:9 6 :JIGDE=>8 HI6IJH D; I=:
6C96B6 6C9 >6 ->K:GH 688DG9>C< ID I=: )_GC7:G<  IGDE=>8 8A6H
H>;>86I>DC
4. Discussion
4.1. Hydrographic characteristics
/=: L6I:G I:BE:G6IJG: L6H =><=:G 9JG>C< I=: 9GN H:6HDC ;DAADL:9
7N I=: G6>CN H:6HDC 6C9 I=: ;ADD9 H:6HDC >C I=: I=G:: G>K:GH !>< 6
CORRECTED PROOF
Table 3
*C:L6N 6C6ANH>H D; I=: H><C>;>86C8: D; H:6HDC6A>IN ;68IDGH L>I= I=: E=NH>8D8=:B>86A 6C9 IDI6A CJIG>B:CIH K6G>67A:H
DBDX 6C96B6 >6
GN -6>CN !ADD9 GN -6>CN !ADD9 GN -6>CN !ADD9
/:BE `  d 66 d 7  d 7  d 6  d 7  d 8  d 6  d 6  d 8
E#  d 6  d 7  d 67  d 6  d 6  d 6  d 6  d 6  d 6
μ.8B  d 6  d 7  d 67  d 6  d 6  d 6  d 6  d 7  d 7
* B<'  d 6  d 67  d 78  d 6  d 6  d 6  d 6  d 6  d 6
.6A EHJ  d 6  d 6  d 6  d 6  d 6  d 7  d 6  d 7  d 7
/. B<'  d 6  d 7  d 67  d 6  d   d 6  d 6  d 78  d 8
+*B<' +  d 6  d 67  d 68  d 6  d 6  d 6  d 68  d 7  d 78
/+ B<' +  d 6  d 6  d 6  d 67  d 7  d 78  d 6  d 6  d 6
)*B<' )*)  d 6  d 6  d 6  d 6  d 6  d 6  d 6  d 6  d 6
)*B<' )*)  d 6  d 67  d 68  d 6  d 67  d 8  d 6  d 67  d 68
)#B<' )#)  d 6  d 67  d 68  d 6  d 6  d 6  d 6  d 7  d 78
/&) B<' )  d 6  d 6  d 6  d 6  d 6  d 6  d 6  d 6  d 6
/) B<' )  d 6  d 6  d 6  d 6  d 67  d 68  d 6  d 67  d 78
=Aaμ<'  d 6  d 6  d 6  d 6  d 6  d 6  d 6  d 6  d 6
/:BE L6I:G I:BE:G6IJG: :A:8IG>86A 8DC9J8I>K>IN * 9>HHDAK:9 DMN<:C .6A .6A>C>IN /. IDI6A 9>HHDAK:9 HDA>9H +*G:68I>K: E=DHE=DGJH /+ IDI6A E=DHE=DGJH )*C>IG6I: >DC )*C>IG>I: >DC )#6BBD
C>JB >DC /&) IDI6A &?:A96=A C>IGD<:C /) IDI6A C>IGD<:C =Aa8=ADGDE=NAAa
6>;;:G:CI A:II:GH 6G: H><C>;>86CIAN 9>;;:G:CI p 
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
Fig. 3. -:68I>K: E=DHE=DGJH 9NC6B>8 >C I=: DBDX 6C96B6 6C9 >6 ->K:GH ;GDB (6G8=  ID (6G8=  9JG>C< I=: 9GN G6>CN 6C9 ;ADD9 H:6HDCH
/=>H B6N 7: 9J: ID HJCHIGD@: *I6 :I 6A  #DL:K:G I=>H K6G>6I>DC
8DJA9 6AHD 7: 9J: ID I=: H6BEA>C< I>B:H .><C>;>86CI L6I:G I:BE:G6IJG:
8=6C<:H G:HJAI >C >BEDGI6CI 8=6C<:H >C I=: <:D<G6E=>8 9>HIG>7JI>DC D;
6FJ6I>8 HE:8>:H 6C9 I=: 7>D<:D8=:B>HIGN D; G>K:G :8DHNHI:BH gAK6G:O
67G>6 :I 6A 
$C I=: DBDX ->K:G I=: L6I:G E# K6AJ: L6H =><=:G >C I=: G6>CN H:6
HDC 9J: ID I=: A:68=>C< D; A6C9 =:6K>AN AD69:9 L>I= E=DHE=6I: 6C9 C>
IGD<:C ;GDB 6<G>8JAIJG: 6C9 ;DG:HI :8DHNHI:BH *H6@6 :I 6A  /=:
ADL:G E# K6AJ:  JC>IH D7H:GK:9 6I HI6I>DC *(6CO6C >C I=: 9GN
H:6HDC >H EGD767AN 6 8DCH:FJ:C8: D; =><= DG<6C>8 B6II:G >C I=: HIG:6B
86JH>C< 6 9:8G:6H: >C E# 9JG>C< I=: G:B>C:G6A>O6I>DC EGD8:HH <J>6G :I
6A  (DG:DK:G L6I:G E# H=DL:9 ADL ;AJ8IJ6I>DCH DK:G I=: I=G::
H:6HDCH >C I=: 6C96B6 6C9 >6 ->K:GH *G<6C>8 B6II:G >CEJIH L:G:
EGD767AN <G:6I:G 6ADC< I=: 6C96B6 ->K:G L6I:GH=:9 :HE:8>6AAN 6I I=:
JG76C HI6I>DC />6HH6AX A:69>C< ID 6 <G69J6A 9:8A>C: >C L6I:G E# 6I
I=: BDJI= G6;;:9DC *C I=: DI=:G =6C9 >C I=: >6 ->K:G =><=
;ADLH =6K: A:9 ID =><=:G CJIG>:CI >CEJIH ;GDB 6<G>8JAIJG6A 6C9 JG76C
DG><>CH I=: =><=:HI K6AJ: D;  E# JC>IH D7H:GK:9 6I 7D>HHD HI6I>DC
9JG>C< I=: *8I G6>CN H:6HDC !>< 7 ;6KDG>C< 6 <G69J6A >C8G:6H: >C
L6I:G E# JE ID  JC>IH 6I HI6I>DC $/=DB6C9>X C >C8G:6H: >C 6A
<6A 68I>K>IN E=DIDHNCI=:H>H ;J:A:9 7N =><=:G >CEJIH D; CJIG>:CIH ;GDB
6<G>8JAIJG6A 6C9 6CI=GDED<:C>8 HDJG8:H 6EE:6GH ID 7: I=: 86JH: D; I=:
<G69J6A >C8G:6H: >C E# 9JG>C< I=: =><= ;ADL E:G>D9 !DG :M6BEA: >C I=:
>6 ->K:G H><C>;>86CI +:6GHDC 8DGG:A6I>DCH D7I6>C:9 7:IL::C E# 6C9
8=ADGDE=NAAar  /67A: . 6C9 E# L>I= G6>C;6AA r
/67A: . HJEEDGI:9 6C >CI:CH: 6A<6A 68I>K>IN 9JG>C< I=: G6>CN H:6HDC
2=:C 6A<6: I6@: JE 86G7DC 9>DM>9: 9JG>C< E=DIDHNCI=:H>H I=:N >C
8G:6H: I=: E# 7N >C8G:6H>C< I=: A:K:A D; =N9GDM>9: >DCH /=: G:K:GH: G:
68I>DC D88JGH 9JG>C< G:HE>G6I>DC L=:C 86G7DC 9>DM>9: >H EGD9J8:9 ADL
:G>C< I=: =N9GDM>9: >DCH I=JH ADL:G>C< I=: E# /=:G:;DG: 6 =><=
L6I:G E#  B6N 7: 6C >C9>86IDG D; E=DIDHNCI=:H>H 7N A6G<:
6BDJCIH D; 6A<6: -6K:C :I 6A 
.>B>A6G 9>HIG>7JI>DCH D; 6C9 /. >C I=: DBDX 6C9 6C96B6
->K:GH >C9>86I:9 I=6I G6>CN >CEJIH HA><=IAN 6AI:G:9 I=: >DC>8 HIG:C<I=
6ADC< I=: HIG:6B (DGG>HDC :I 6A  *C I=: DI=:G =6C9 I=: >6
->K:G L6H HIGDC<AN B>C:G6A>O:9 9JG>C< I=: 9GN H:6HDC >: 6C9 /.
L:G: H><C>;>86CIAN =><= 9JG>C< I=: 9GN H:6HDC p  9J: ID I=: ADL
L6I:G G6I: G:C:L6A 8DBE6G:9 ID I=: G6>CN 6C9 ;ADD9 H:6HDCH CDI=:G
>BEDGI6CI ;68IDG >H I=6I  /. 6C9 H6A>C>IN 6G: 6;;:8I:9 7N I=: <:DA
D<N D; I=: 6G:6 I=GDJ<= L6I:G ;ADLH EG:8>E>I6I>DC 6C9 I=: :K6EDG6I>DC
EG:8>E>I6I>DC EGD8:HH /=:H: HIG:6BH E6HH I=GDJ<= 6G:6H D; 8A6N HD>AH
;:GG6AA>I>8 L=>8= I:C9 ID >C8G:6H: 6C9 /. 9J: ID I=: EG:H:C8: D;
B6I:G>6AH I=6I >DC>O: L=:C L6H=:9 >C L6I:G =6I:G>6 6C9 %6>C 
'DL A:K:AH D; H6A>C>IN  EHJ 6C9 /.  B<' LDJA9 6AHD
EGDBDI: 6C >C8G:6H: >C 6A<6A EGD9J8I>K>IN >C I=: DBDX 6C96B6 6C9
>6 ->K:GH .DG:CH:C :I 6A 
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
Fig. 4. )>IG6I: >DCH 9NC6B>8 >C I=: DBDX 6C96B6 6C9 >6 ->K:GH ;GDB (6G8=  ID (6G8=  9JG>C< I=: 9GN G6>CN 6C9 ;ADD9 H:6HDCH
/=: I=G:: G>K:GH L:G: L:AADMN<:C6I:9 9JG>C< I=: ;ADD9 H:6HDC
/67A: . $C 8DCIG6HI ADL A:K:AH D; 9>HHDAK:9 DMN<:C C:6G =NEDM>6
L:G: D7H:GK:9 >C BDHI D; I=: DBDX ->K:G HI6I>DCH 9JG>C< I=: 9GN H:6
HDC DK:G I=: ILDN:6G H6BEA>C< E:G>D9 /=>H LDJA9 7: I=: G:HJAI D; >C
8G:6H:9 CJIG>:CI AD69>C< 6C9 DG<6C>8 B6II:G 9:8DBEDH>I>DC A:6K:H 9:
7G>H 6C9 6C>B6A L6HI:H L=>8= INE>86AAN D88JGH 9JG>C< E:G>D9H D; K:GN
ADL ;ADL DG >C G>K:GH L>I= A>B>I:9 ;AJH=>C< G6I:H <J>6G :I 6A 
DCA:N :I 6A  (DG:DK:G ADL DMN<:C A:K:AH 9JG>C< I=: 9GN H:6HDC
>C I=: DBDX ->K:G 86C A:69 ID I=: :M8:HH>K: G:A:6H: D; CJIG>:CIH ;GDB
I=: H:9>B:CI L=>8= EGDBDI:H 6A<6A 7ADDBH 6D :I 6A  $C 8DC
IG6HI I=: 6C96B6 6C9 >6 ->K:GH DMN<:C6I>DC L6H BJ8= 7:II:G >C I=:
9GN H:6HDC ;6KDG:9 EGD767AN 7N 6 7:II:G BDK:B:CI D; I=: L6I:G
B6HH:H ":C:G6AAN I=: G>K:GH L:G: L:AA DMN<:C6I:9 9JG>C< I=: G6>CN
H:6HDC :M8:EI 6I HI6I>DC )O> 6C96B6 ->K:G IG>7JI6GN 6C9 6I I=:
DBDX 6C9 6C96B6 ->K:GH :HIJ6G>:H HI6I>DCH *6HH6B 6C9 
G6;;:9DC /=: E:GB6C:CI BDK:B:CI D; L6I:G B6HH:H IDL6G9H I=:H:
8DC;AJ:CIH H::B:9 ID ;6KDG I=: E:G>D9>8 9:EDH>I>DC D; A6G<: FJ6CI>I>:H D;
DG<6C>8 B6II:G 6C9 =:I:GDIGDE=>8 768I:G>6 9:8DBEDH>I>DC L=>8= 86JH:H
6 G6E>9 9GDE >C I=: DMN<:C A:K:A (6AA>C :I 6A .6GB6 :I 6A
 * 8DC8:CIG6I>DCH D; I=: DBDX 6C96B6 6C9 >6 ->K:GH 8D>C
8>9:9 L>I= I=: G:HJAIH G:EDGI:9 7N "JEI6 :I 6A   B<' >C
I=: )6GB696 ->K:G $C9>6 6C9 7N G>BDGD :I 6A   B<
' >C I=: *GD<D9D ->K:G )><:G>6 $C I=:H: IGDE>86A 6G:6H ADL * 8DC
8:CIG6I>DCH G:HJAI:9 ;GDB I=: G:A:6H: D; L6HI:H G>8= >C DG<6C>8 B6II:G
6C9 CJIG>:CIH C:6G I=: G>K:G H>I: 6C9 I=:C ;GDB I=: >C8G:6H:9 B>8GD7>6A
68I>K>IN D88JGG>C< 9JG>C< I=: 9:<G696I>DC D; DG<6C>8 B6II:G
.DB: 6JI=DGH HJ8= 6H "G6N :I 6A 16FJ:G.JCN:G 6C9 J6GI:
 :HI67A>H=:9 >C I=:>G LDG@ 6 8DCK:CI>DC6A K6AJ: D; *  B<'
ID 9:H><C6I: =NEDM>8 L6I:GH L=>8= 86C >BE68I ;>H=:H 6C9 8GJHI68:6CH
A>;: /=>H I=G:H=DA9 L6H CDI G:68=:9 >C DJG HIJ9N B>C>BJB
K6AJ: B<' /=:G: L6H CD 6EE6G:CI G>H@ D; BDGI6A>IN ;DG 6FJ6I>8
HE:8>:H >C I=: DBDX 6C96B6 6C9 >6 ->K:GH #DL:K:G I=: <G:6I 9>
K:GH>IN D; E=NH>DAD<>86A G:HEDCH:H ID =NEDM>6 EDH:H H:G>DJH D7HI68A:H ID
6CN 6II:BEI ID EG:9>8I 8DBBJC>IN 6C9 :8DHNHI:B G:HEDCH:H ID ADL 6B
7>:CI DMN<:C 8DC9>I>DCH 76H:9 DC G:HEDCH:H D; >C9>K>9J6A HE:8>:H
#:GCSC9:O(>G6C96 :I 6A 
4.2. Spatio-temporal distribution of nutrients and Chl-a
4.2.1. Reactive phosphorus dynamic
/=: G:68I>K: E=DHE=DGJH +* 9NC6B>8 >C I=: DBDX 6C96B6
6C9 >6 ->K:GH 9JG>C< I=: I=G:: =N9GDAD<>86A H:6HDCH 6G: EG:H:CI:9 DC
B6EH D; !>< +*8DC8:CIG6I>DCH >C I=: DBDX ->K:G 6I 6AA HI6I>DCH
L:G: >C I=: =><=:HI G6C<:  B<' + >C I=: 9GN H:6HDC EDH
H>7AN 9J: ID H:9>B:CI >CEJIH GJCD;;H ;GDB 8JAI>K6I:9 A6C9 JG76C 9>H
8=6G<:H 6C9 JCIG:6I:9 L6HI:L6I:G =6I:G>6 6C9 %6>C  'DL DMN
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
Fig. 5. .:6HDC6A K6G>6I>DCH D; 6 C>IG>I: >DCH 7 6BBDC>JB >DCH 6C9 8 =ADGDE=NAAa >C I=: DBDX 6C96B6 6C9 >6 ->K:GH ;GDB (6G8=  ID (6G8= 
9JG>C< I=: 9GN G6>CN 6C9 ;ADD9 H:6HDCH
<:C A:K:AH 8ADH: ID =NEDM>6 L:G: D7H:GK:9 >C BDHI HI6I>DCH D; I=: DBDX
->K:G /67A: . 9JG>C< I=: 9GN H:6HDC L=>8= 8DJA9 A:69 ID I=: :M8:H
H>K: G:A:6H: D; E=DHE=DGJH ;GDB I=: H:9>B:CIH 6C9 EGDBDI:H 6A<6: EGD
A>;:G6I>DC 6D :I 6A  JG>C< I=: G6>CN 6C9 ;ADD9 H:6HDCH I=:
L6H=DJI :;;:8I G:HJAI:9 >C =><= +*8DC8:CIG6I>DCH JEHIG:6B L=>8=
I=:C <G69J6AAN 9:8G:6H:9 >C I=: 9>G:8I>DC D; I=: 8JGG:CIH 6C9 ;>C6AAN >C
8G:6H:9 H=6GEAN >C I=: :HIJ6G>:H /=: B>M>C< D; HIGDC< CDGI=:GC G>K:G
8JGG:CIH L>I= I>96A 8JGG:CIH ;GDB :HIJ6G>:H G:HJHE:C9:9 I=: H:9>B:CI6GN
E=DHE=DGJH HID8@ 688JBJA6I:9 6I I=: 7DIIDB 9JG>C< E:G>D9H D; 86AB
<J>6G :I 6A D:A=D :I 6A  (DG:DK:G I=: ADL 8DC8:CIG6
I>DCH D7I6>C:9 6I I=: (6CO6C IG>7JI6GN  B<' + HI6I>DC
*(6CO6C 9JG>C< I=: ;ADD9 H:6HDC 86C 7: :MEA6>C:9 7N 6 <G:6I:G 9>
AJI>DC :;;:8I <>K:C I=: G>H>C< L6I:G A:K:AH 9JG>C< ;ADD9>C<
+*8DC8:CIG6I>DCH >C I=: >6 ->K:G L:G: 6AHD >C I=: =><=:HI
G6C<:  B<' + JEHIG:6B HI6I>DC $ 9JG>C< I=: 9GN
H:6HDC 6C9 C:6G I=: BDJI= HI6I>DCH $&G>C9?67D 6C9 $
/=DB6C9>X (DG:DK:G I=: $N6BX 96B 6C9 $7D>HHD 8>IN
HI6I>DCH =69 >CI:GB:9>6I: +*8DC8:CIG6I>DCH  B<'
+ 9JG>C< I=: 9GN H:6HDC '6C9 JH: 6GDJC9 I=: JEHIG:6B L6I:GH=:9
:< 8D8D6GJ77:G 8JAIJG:H 6C9 6I I=: >6 ->K:G :HIJ6GN :< E6AB
<GDK:GJ77:G 8JAIJG:H 6EE:6G:9 ID EGDK>9: BDG: +*I=6C JG76C
6G:6 /=>H =><=A><=IH I=: 9:;>C>I: >BE68I D; ;6GB>C< 6G:6H DC I=>H
HIG:6B 6C9 >IH 8DCH:FJ:C8:H HJ8= 6H 6A<6: 7ADDB (DG:DK:G I=:
=JCI>C< ;ADL G6I:H D; I=: N6BX 96B A6@: 9JG>C< >IH :BEIN>C< 6C9
>IH <G:6I 9:EI= >C;AJ:C8: I=: CJIG>:CIH HJEEAN 9DLCHIG:6B D; I=: >6
->K:G 6H H=DLC 7N <J>6G :I 6A  >C I=:>G LDG@H /=: ADL:HI
+*8DC8:CIG6I>DCH G6C<:  B<' + D7I6>C:9 >C I=:
G6>CN H:6HDC G:;A:8I:9 6 K:GN B6G@:9 9>AJI>DC :;;:8I /=:G:;DG: G6>C
;6AA EA6N:9 6 G:<JA6IDGN GDA: >C I=: E=DHE=DGJH AD69 >C I=: >6 ->K:G
+:6GHDC r  /67A: . #DL:K:G GJCD;; 6C9 :GDH>DC
EGD8:HH:H :HE:8>6AAN 9JG>C< ;ADD9 :E>HD9:H L:G: I=: B6>C BD9: D;
E=DHE=DGJH IG6CH;:G >C I=>H G>K:G 6H :K>9:C8:9 7N I=: K6AJ:H L=>8=
<G69J6AAN >C8G:6H:9 >C I=: 9>G:8I>DC D; I=: 8JGG:CI ': )DZ :I 6A

H ;DG I=: 6C96B6 ->K:G I=: ADL:HI +*8DC8:CIG6I>DCH L:G: D7
I6>C:9 >C I=: 9GN 6C9 G6>CN H:6HDCH  B<' + L=>A: I=:
;ADD9 H:6HDC G:8DG9:9 I=: =><=:HI K6AJ:H  B<' + '6C9
JH: 6GDJC9 I=: L6I:GH=:9 !6GB>C<E6HIJG: 6C9 JG76C 68I>K>I>:H 9>9
CDI =6K: 6 <G:6I >BE68I DC I=: E=DHE=DGJH >CEJI >C I=: 6C96B6 ->K:G
9JG>C< I=: 9GN 6C9 G6>CN H:6HDCH (DG:DK:G 9JG>C< I=: G6>CN H:6HDC
I=: 9>AJI>DC 6C9 IG6CHEDGI :;;:8IH 9J: ID 6 HIGDC< HJG;68: L6I:G 8JGG:CI
6EE:6G ID D88JG ;GDB JEHIG:6B ID 9DLCHIG:6B 6C9 8G:6I: 6 =><= E:6@
 B<' + 6I I=: G>K:G :HIJ6GN G6;;:9DC B6CD :I 6A
 -:A:6H:9 E=DHE=DGJH ;GDB H:9>B:CIH EGDBDI:9 7N I=: B>M>C< D;
HIGDC< CDGI=:GC G>K:G 8JGG:CIH L>I= I=: I>96A 8JGG:CIH D; I=: :HIJ6GN 86C
6AHD 86JH: =><= +*8DC8:CIG6I>DCH 6I I=: BDJI= D; I=: 6C96B6
->K:G 9JG>C< I=: G6>CN H:6HDC ):<G>C :I 6A  +*8DC8:CIG6
I>DCH >C I=: DBDX 6C96B6 6C9 >6 ->K:GH 8D>C8>9:9 L>I= I=: G:HJAIH
G:EDGI:9 7N (76N: :I 6A   B<' + >C I=: .:C:<6A
->K:G 6C9 7N G>BDGD :I 6A   B<' + >C I=: *GD<D9D
->K:G )><:G>6 >BE68I:9 7N HA6J<=I:G=DJH: :;;AJ:CIH /=:G:;DG: I=:
DBDX 6C96B6 6C9 >6 ->K:GH L:G: >BE68I:9 7N =JB6C 6<G>8JAIJG6A
6C9 JG76C 68I>K>IN
4.2.2. Nitrate ions dynamic
/=: C>IG6I: >DCH 9NC6B>8 >C I=: DBDX 6C96B6 6C9 >6 ->K:GH
9JG>C< I=: I=G:: =N9GDAD<>86A H:6HDCH 6G: EG:H:CI:9 DC B6EH D; !><
/=: C>IG6I: 8DC8:CIG6I>DCH >C I=: DBDX ->K:G 6I 6AA HI6I>DCH L:G: >C
I=: =><=:HI G6C<:  B<' )*) >C I=: 9GN H:6HDC I=:C
@:EI HJ7HI6CI>6AAN I=: H6B: 9>HIG>7JI>DC >C I=: G6>CN H:6HDC :M8:EI 6I
I=: *C>6HHJX 6C9 *AXEX HI6I>DCH L=:G: I=: ADL:HI G6C<: L6H
G:68=:9  B<' )*) )>IGD<:C ;:GI>A>O:G GJCD;; ;GDB 6<G>
8JAIJG6A A6C9 6C9 >C H>IJ DG<6C>8 IG6CH;DGB6I>DCH 86C 7: 8DCH>9:G:9 C>
IG6I:H HDJG8:H >C I=: 9GN H:6HDC #6C :I 6A  <G69J6A 9>AJI>DC :;
;:8I L6H E:G8:EI>7A: 9JG>C< ;ADD9>C<H ;GDB I=: 8DC;AJ:C8: 6G:6 D; I=:
*(6CO6C  B<' )*) ID I=: BDJI= D; I=: DBDX ->K:G
 B<' )*) )>IG>8 C>IGD<:C >H ;DJC9 >C I=: 6FJ6I>8 :CK>GDC
B:CI B6>CAN I=GDJ<= 6<G>8JAIJG6A EGD8:HH:H C>IGD<:CDJH ;:GI>A>O:GH
HJ8= 6H HD9>JB C>IG6I: 6C9 6BBDC>JB C>IG6I: )>IGD<:C ADHH:H ;GDB

CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
6<GD:8DHNHI:BH D88JG I=GDJ<= A:68=>C< B6>CAN D; C>IG6I: -_II>C< :I 6A
 /=: DBDX 6C96B6 6C9 >6 ->K:GH L6I:GH=:9H L:G: HJ7
?:8I:9 ID 6C >CI:CH>;>86I>DC D; 86H= 8GDE 8JAI>K6I>DC GJ77:G 8D8D6 8D;
;:: :I8 DK:G I=: E6HI ILD 9:869:H G:FJ>G>C< BDG: ;:GI>A>O:GH ID >C
8G:6H: I=:>G EGD9J8I>K>IN /=>H =6H 8DCIG>7JI:9 ID :CG>8=>C< JEHIG:6B
L6I:GH >C C>IG6I:H :HE:8>6AAN 6I I=: *(6CO6C 6;X86D 6C9
$>6CDJ6 HI6I>DCH 9JG>C< I=: 9GN 6C9 G6>CN H:6HDCH %JHI 6H >C I=:
DBDX ->K:G C>IG6I: 8DC8:CIG6I>DCH >C I=: >6 ->K:G 9JG>C< I=: 9GN H:6
HDC L:G: >C I=: =><=:HI G6C<:  B<' )*) I=:C I=:N 9:
8G:6H:9 HA><=IAN 9JG>C< I=: G6>CN H:6HDC JEHIG:6B 6I >6CDJ6 6C9
9DLCHIG:6B 6I HI6I>DCH C:6G I=: BDJI= $ 6C9 $
 B<' )*) .I6I>DCH $ N6BX 96B 6C9 $ =69
I=: ADL:HI C>IG6I: 8DC8:CIG6I>DCH  B<' )*) EGD767AN
9J: ID I=: N6BX 6B /=: ;AJH=>C< G6I:H D; I=: 96B A6@: 6C9 >IH <G:6I
9:EI= >C;AJ:C8:9 I=: HJEEAN D; C>IG6I:H JEHIG:6B D; I=: G:H:GKD>G
(D=H:CEDJG :I 6A <J>6G :I 6A  JG>C< I=: ;ADD9 H:6HDC
C>IG6I: 8DC8:CIG6I>DCH L:G: >C I=: >CI:GB:9>6I: G6C<: JEHIG:6B
 B<' )*) I=:C <G69J6AAN >C8G:6H:9 8DBE6G:9 ID I=:
IG:C9 D; I=: G6>CN H:6HDC >C I=: 9>G:8I>DC D; I=: 8JGG:CIH ID I=: BDJI=
)>IG6I: 8DC8:CIG6I>DCH >C I=: 6C96B6 ->K:G L:G: >C I=: =><=:HI G6C<:H
 B<' )*) >C I=: 9GN H:6HDC 6C9  B<'
)*) >C I=: G6>CN H:6HDC /=DH: D; I=: ;ADD9 H:6HDC I=GDJ<=DJI I=:
G>K:G L:G: >C I=: ADL:HI G6C<:  B<' )*) L>I= 6 HA><=I
>C8G:6H: 6I I=: '6=DJ HI6I>DC  B<' )*) )>IG6I:H 6E
E:6G:9 ID A>B>I 6A<6A <GDLI= =:C8: I=:>G ADL 6K6>A67>A>IN 9JG>C< I=:
;ADD9 H:6HDC )<6I>6 6C9 /6NADG  /=: H:9>B:CIH 8DJA9 6AADL I=:
G:BDK6A D; C>IGD<:C ;GDB I=: L6I:G 7N E:GB6C:CIAN 7JGN>C< C>IGD<:
CDJH DG<6C>8 8DBEDJC9H 1:C@6I:H= 6C9 CH=JB6A>  $C 699>
I>DC 9>AJI>DC 6C9 IG6CHEDGI :;;:8IH ;GDB HIGDC< HJG;68: L6I:GH 6EE:6G:9
ID D88JG >C I=: L6I:G 7D9N 9DLCHIG:6B 9JG>C< I=: ;ADD9 H:6HDC B6CD
:I 6A 
4.2.3. Chlorophyll-a dynamic
/=: 8=ADGDE=NAAa=Aa 9NC6B>8 >C I=: DBDX 6C96B6 6C9 >6
->K:GH 9JG>C< I=: I=G:: =N9GDAD<>86A H:6HDCH 6G: EG:H:CI:9 DC !>< 8
/=: =><=:G =Aa8DC8:CIG6I>DC  μ<' 6C9 ADL:G DC:  μ<'
L:G: D7H:GK:9 9DLCHIG:6B D; I=: DBDX ->K:G 9JG>C< I=: ;ADD9 H:6HDC
G:HE:8I>K:AN 6I I=: G>K:G BDJI= *6HH6B 6C9 I=: *DCDJ6 HI6
I>DC ":C:G6AAN 6AA I=G:: G>K:GH BDJI=H :M=>7>I:9 =><= 8DC8:CIG6I>DCH
D; 8=ADGDE=NAAa9JG>C< I=: I=G:: =N9GDAD<>8 H:6HDCH /=: =N9GDAD<>86A
EGD;>A:H 6C9 68I>K>I>:H 6ADC< I=: JEHIG:6B G>K:GH L6I:GH=:9H B6@: I=:B
>BEDGI6CI HDJG8:H D; CJIG>:CIH ID 9DLCHIG:6B =67>I6IH 46H>C :I 6A
 H 6C :M6BEA: 9JG>C< I=: 9GN 6C9 ;ADD9 H:6HDCH =Aa8DC8:C
IG6I>DCH L:G: ADL JEHIG:6B :M8:EI 6I I=: *(6CO6C HI6I>DC L=:G:
GJCD;; L6I:G AD69:9 L>I= C>IG6I:H A:9 ID 6C >C8G:6H: >C E=NIDEA6C@IDC
68I>K>IN 6GGDHD :I 6A  /=: 6HHD8>6I>DCH 7:IL::C I=: 8=ADGD
E=NAAa67JC96C8: L>I= I=: C>IG6I: >DCH 6C9 G:68I>K: E=DHE=DGJH 9N
C6B>8H L:G: E:G;DGB:9 JH>C< +:6GHDC 8DGG:A6I>DC /67A: . =ADGD
E=NAAaL6H EDH>I>K:AN 8DGG:A6I:9 L>I= +*>C I=: 6C96B6 r 
6C9 >6 r  ->K:GH 6C9 L>I= )*>C I=: DBDX ->K:G
r  !JGI=:GBDG: 8=ADGDE=NAAaL6H C:<6I>K:AN 8DGG:A6I:9 L>I=
G>K:G 9>H8=6G<: r >C I=: 6C96B6 ->K:G 6C9 L>I= 9>HHDAK:9
DMN<:C * r >C I=: >6 ->K:G /=: +:6GHDC 8DGG:A6I>DC 8D
:;;>8>:CIH HJ<<:HI I=6I I=: 8=ADGDE=NAAa67JC96C8: >C I=: I=G:: G>K:GH
K6G>:9 A>C:6GAN L>I= CJIG>:CIH +* )* 6C9 E=NH>8D8=:B>86A E6G6
B:I:GH G>K:G 9>H8=6G<: * /=: 8=ADGDE=NAAa8DC8:CIG6I>DCH >C
8G:6H:9 L>I= I=: >CEJI D; +*>C I=: 6C96B6 6C9 >6 ->K:GH .>B>
A6GAN C>IG6I: >CEJIH >C8G:6H:9 L>I= 8=ADGDE=NAAa8DC8:CIG6I>DCH >C I=:
DBDX ->K:G B6>CAN 9JG>C< I=: G6>CN H:6HDC /=:H: G:HJAIH 8DJA9 >C9>
86I: 6 A>B>I6I>DC D; EG>B6GN EGD9J8I>DC 7N C>IGD<:C >C I=: DBDX ->K:G
6C9 7N E=DHE=DGJH >C I=: 6C96B6 6C9 >6 ->K:GH G:HE:8I>K:AN 9JG>C<
I=: G6>CN H:6HDC 16C 9:G 5:: 6C9 =DJ  /=: ADL:G C>IG6I: 8DC
8:CIG6I>DCH D7I6>C:9 9JG>C< I=: ;ADD9 H:6HDC 8DB7>C:9 L>I= I=: >C
8G:6H: >C +*8DC8:CIG6I>DCH 9JG>C< I=: H6B: E:G>D9 H::B:9 ID >C9>
86I: <G:6I:G JEI6@: D; C>IG6I: 7N 6A<6: /=:G:;DG: C>IG6I: H::B:9 ID
=6K: 6 H><C>;>86CI G:<JA6IDGN :;;:8I DC I=: 6A<6A EDEJA6I>DC 9JG>C< I=:
;ADD9 H:6HDC #DGC:  JG>C< I=: 9GN H:6HDC I=: =><=:G G6C<:H D;
+*6C9 C>IG6I: 8DC8:CIG6I>DCH >C I=: DBDX 6C9 >6 ->K:GH EGD
BDI:9 6C >C8G:6H:9 6A<6A EGDA>;:G6I>DC /=>H =><= 6K6>A67>A>IN D; +*
6C9 C>IG6I: >H EGD767AN A>C@:9 ID I=: 7>D<:D8=:B>86A 8N8A:H D; I=:H: CJ
IG>:CIH >C I=: 9>;;:G:CI G>K:GH C>IG>;>86I>DC G:A:6H: D; E=DHE=DGJH 6C9
C>IGD<:C ;GDB I=: H:9>B:CIH 6C9 I=: ADL G:C:L6A D; L6I:G 9JG>C< I=>H
E:G>D9 GJO :I 6A )<JN:C :I 6A  *K:G6AA I=: B6EE>C<
9>HIG>7JI>DCH 6C9 I=: EG:H:C8: D; 6HHD8>6I>DCH 7:IL::C I=: 67JC96C8:
D; 8=ADGDE=NAAa6C9 I=: :CK>GDCB:CI6A E6G6B:I:GH B:6HJG:9 H=DL I=6I
I=: 8=ADGDE=NAAa9NC6B>8 >C G>K:GH 8DJA9 7: 9>8I6I:9 7N I=: 6K6>A67>A>IN
D; C>IG6I: >DCH 6C9 G:68I>K: E=DHE=DGJH ;GDB ED>CI HDJG8:H JG76C 9>H
8=6G<:H 6C9 9>;;JH: HDJG8:H 6<G>8JAIJG6A 6H L:AA 6H G>K:G 9>H8=6G<:
#6D :I 6A 
4.2.4. Nitrite and ammonium ions dynamics
/=: HE6I>DI:BEDG6A 9>HIG>7JI>DCH D; I=: C>IG>I: >DCH )* >C I=:
DBDX 6C96B6 6C9 >6 ->K:GH 9JG>C< I=: 9GN G6>CN 6C9 ;ADD9 H:6
HDCH 6G: EG:H:CI:9 DC !>< 6 )*L6H I=: A:6HI 67JC96CI 9>HHDAK:9 C>
IGD<:C CJIG>:CI 9JG>C< I=: HIJ9N E:G>D9 /=: G6>CN H:6HDC =69 I=: =><=
:HI 8DC8:CIG6I>DCH L>I= 6C 6K:G6<: 8DC8:CIG6I>DC D;
 d  B<' )*) L=>A: I=: ADL:HI 8DC8:CIG6I>DCH D; C>
IG>I: L:G: G:8DG9:9 >C I=: ;ADD9 H:6HDC L>I= 6C 6K:G6<: 8DC8:CIG6I>DC D;
 d  B<' )*) /=: C>IG>I: >DC >H 6C >CI:GB:9>6I: >C I=:
DM>96I>DC D; 6BBDC>6 ID C>IG6I: #><= A:K:AH D; C>IG>I: >C G>K:G L6I:GH
B6N >C9>86I: EDAAJI>DC 6C9 6 G>H@ D; IDM>8>IN ID 6FJ6I>8 A>;: 6I G:A6I>K:AN
ADL 8DC8:CIG6I>DCH   B<' )*) DGG>K:6J  /=>H
;DGB D; C>IGD<:C 86C 7: JH:9 6H 6 HDJG8: D; CJIG>:CIH ;DG 6A<6: 6C9 >IH
EG:H:C8: EGDBDI:H I=:>G EGDA>;:G6I>DC 3>6 :I 6A  /=: I=G:H=DA9
D;  B<' )*) >H <:C:G6AAN :M8::9:9 >C I=: DBDX 6C96B6
6C9 >6 ->K:GH E6GI>8JA6GAN 9JG>C< I=: 9GN 6C9 G6>CN H:6HDCH /=JH I=:
G>K:G L6I:GH L:G: EDAAJI:9 7N C>IG>I: >DCH (6CN :;;AJ:CI 9>H8=6G<:H >C
8AJ9>C< L6HI:L6I:G 6G: G>8= >C 6BBDC>6 L=>8= >C IJGC 86C A:69 ID >C
8G:6H:9 C>IG>I: 8DC8:CIG6I>DCH >C G>K:GH L6I:G #6GI:G :I 6A 
26@>96 6C9 ':GC:G 
/=: HE6I>DI:BEDG6A 9>HIG>7JI>DCH D; I=: 6BBDC>JB >DCH )# >C
I=: DBDX 6C96B6 6C9 >6 ->K:GH 9JG>C< I=: 9GN G6>CN 6C9 ;ADD9
H:6HDCH 6G: EG:H:CI:9 DC !>< 7
/=: ;ADD9 H:6HDC H=DL:9 I=: ADL:HI )#8DC8:CIG6I>DCH >C 6AA
G>K:GH L>I= 6C 6K:G6<: 8DC8:CIG6I>DC D;  d  B<' )#)
)#8DC8:CIG6I>DCH 9>9 CDI H=DL 6 8A:6G IG:C9 9JG>C< I=: 9GN 6C9
G6>CN H:6HDCH >C I=: DBDX 6C9 6C96B6 ->K:GH p  6AI=DJ<=
ILD =><= E:6@ 8DC8:CIG6I>DCH  6C9  B<' )#) G:HE:8
I>K:AN L:G: D7H:GK:9 6I I=: BDJI=H HI6I>DCH *6HH6B 6C9 
'6=DJ D; I=: DBDX 6C9 6C96B6 ->K:GH >C %JC: H ;DG I=: >6 ->K:G
)#8DC8:CIG6I>DCH L:G: =><=:G 9JG>C< I=: 9GN H:6HDC I=6C 9JG>C< I=:
G6>CN DC: /=: ADL )*6C9 )#8DC8:CIG6I>DCH >C *8ID7:G 86C 7: 6I
IG>7JI:9 ID I=: 9>AJI>DC :;;:8I <:C:G6I:9 7N I=: >C8G:6H: >C I=: G>K:GH L6
I:G KDAJB: 6H 6 G:HJAI D; EG:8>E>I6I>DC /=>H =6H 6AHD 7::C D7H:GK:9 7N
.8=:CDC: :I 6A   >C I=: ADL:G E6GI D; I=: .6A69D ->K:G
L=>8= :BEI>:H >CID I=: .6B7DGDB7]C 76N )6IJG6A L6I:GH JCEDAAJI:9
8DCI6>C G:A6I>K:AN ADL 6BDJCIH D; 6BBDC>JB >DCH INE>86AAN
 B<' )#) 8:GD  /=>H I=G:H=DA9 L6H <:C:G6AAN :M
8::9:9 >C I=: DBDX 6C96B6 6C9 >6 ->K:GH 9JG>C< I=: I=G:: H:6
HDCH /=JH I=: G>K:G L6I:GH L:G: HJ7?:8I ID EGDA>;>8 6A<6A 7ADDBH L=>8=
=69 69K:GH: :;;:8IH DC 6FJ6I>8 A>;: ADC< I=: G>K:GH L6I:GH=:9H CJB:G
DJH 9>H8=6G<:H D; :;;AJ:CIH 6C9 DG<6C>8 L6HI: >C8AJ9>C< 9DB:HI>8
L6HI:L6I:G DG 6C>B6A B6CJG: G>8= >C 6BBDC>JB >DCH 6GG>K:9 9>G:8IAN
>C I=: L6I:G 7D9>:H /=:H: G:A:6H:H 8DB7>C:9 L>I= I=: B>8GD7>DAD<>86A
9:8DBEDH>I>DC D; C>IGD<:C 8DBEDJC9H >C DG<6C>8 B6II:G G:HJAI:9 >C >C
8G:6H:9 )#8DC8:CIG6I>DCH >C I=: G>K:GH L6I:GH
4.2.5. Comparison to rivers and lakes in the world
6I6 ;GDB I=: EG:H:CI HIJ9N L:G: 8DBE6G:9 L>I= I=DH: ;GDB I=: A>I
:G6IJG: /67A:  /=: 6BBDC>JB >DCH G:68I>K: E=DHE=DGJH 6C9

CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
Table 4
DBE6G>HDC D; CJIG>:CIH 6C9 8=ADGDE=NAAa8DC8:CIG6I>DCH >C I=: DBDX 6C96B6 6C9 >6 ->K:GH L>I= DI=:G HIJ9>:H >C I=: LDGA9
)JIG>:CI ->K:GA6@: G:6 (>CB6M -:;:G:C8:H )JIG>:CI ->K:GA6@: G:6 (>CB6M -:;:G:C8:H
)#
B<' )#)
Temperate )*
B<' )*)
Temperate
&6GA6 "G::8:  +6E69>B>IG>DJ :I 6A  &6GA6 "G::8:  +6E69>B>IG>DJ :I 6A 
.E:G8=:>DH "G::8:  (6G@D<>6CC> :I 6A  .E:G8=:>DH "G::8:  (6G@D<>6CC> :I 6A 
6E: !:6G 0.  (6AA>C :I 6A  6E: !:6G 0.  (6AA>C :I 6A 
Tropical Tropical
"J6M>C9>76 G6O>A <J>6G :I 6A  "J6M>C9>76 G6O>A  <J>6G :I 6A 
4:AADL =>C6  26C< :I 6A  4:AADL =>C6  26C< :I 6A 
DC<D -  :H8N :I 6A  DC<D -  :H8N :I 6A 
(6G6 &:CN6  (6H:H: :I 6A  (6G6 &:CN6  (6H:H: :I 6A 
.:C:<6A .:C:<6A  (76N: :I 6A  .:C:<6A .:C:<6A  (76N: :I 6A 
Comoé 0.020.62 Our study Comoé 0.261.90 Our study
Bandama 0.010.52 Bandama 0.333.60
Bia 0.010.14 Bia 0.271.40
)*
B<' )*)
Temperate )*
B<' )*)
Tropical
&6GA6 "G::8:  +6E69>B>IG>DJ :I 6A  $B7J6WJ G6O>A  <J>6G :I 6A 
.E:G8=:>DH "G::8:  (6G@D<>6CC> :I 6A  4:AADL =>C6  26C< :I 6A 
6E: !:6G 0. (6AA>C :I 6A  .:C:<6A .:C:<6A  (76N: :I 6A 
Comoé 0.0010.021 Our study
Bandama 0.0020.015
Bia 0.0010.025
Temperate Temperate
&6GA6 "G::8:  +6E69>B>IG>DJ :I 6A  &6GA6 "G::8:  +6E69>B>IG>DJ :I 6A 
.E:G8=:>DH "G::8:  (6G@D<>6CC> :I 6A  .E:G8=:>DH "G::8:  (6G@D<>6CC> :I 6A 
6E: !:6G 0.  (6AA>C :I 6A  6E: !:6G 0.  (6AA>C :I 6A 
+*
B<' +
Tropical =Aa
μ<'
Tropical
$B7J6WJ G6O>A  <J>6G :I 6A  $B7J6WJ G6O>A  <J>6G :I 6A 
"J6M>C9>76 G6O>A  <J>6G :I 6A  "J6M>C9>76 G6O>A  <J>6G :I 6A 
"76@D )><:G>6  G>BDGD 6C9 &:@:  (6G6 &:CN6  (6H:H: :I 6A 
.:C:<6A .:C:<6A  (76N: :I 6A  DC<D -  :H8N :I 6A 
4:AADL =>C:  26C< :I 6A  4:AADL =>C:  26C< :I 6A 
Comoé 0.020.10 Our study Comoé 6.21164 Our study
Bandama 0.010.12 Bandama 9.4596.4
Bia 0.030.11 Bia 9.1892.6
8=ADGDE=NAAa8DC8:CIG6I>DCH D; I=>H HIJ9N L:G: BJ8= ADL:G I=6C I=DH:
D; &6GA6 '6@: >C "G::8: +6E69>B>IG>DJ :I 6A  /=>H 8DJA9 7: :M
EA6>C:9 7N I=: A:C<I= D; HI6N 6C9 I=: ADL IJGCDK:G D; I=: '6@: &6GA6 L6
I:GH L=>8= G:HJAIH >C BDG: CJIG>:CI 688JBJA6I>DC 6C9 =><= 8DC8:CIG6
I>DCH $C 8DCIG6HI :M8:EI 9JG>C< I=: 9GN H:6HDC I=: ^I: 9$KD>G: ->K:GH
7:C:;>I 6 8DCHI6CI L6I:G G:C:L6A A:69>C< ID 6 9>AJI>DC :;;:8I DC I=: DC:
=6C9 ADL CJIG>:CI 8DC8:CIG6I>DCH JEHIG:6B <:C:G6AAN 6C9 I=:C 6 CJ
IG>:CI IG6CHEDGI :;;:8I IDL6G9H I=: BDJI=H D; I=: G>K:GH DC I=: DI=:G
=6C9 =NE:G:JIGDE=>8 6G:6H /=: G:68I>K: E=DHE=DGJH 6C9 6BBDC>JB
>DCH 8DC8:CIG6I>DCH L:G: L>I=>C I=: G6C<:H D; HDB: G>K:GH >C 2:HI
;G>86 .:C:<6A ->K:G  B<'+ (76N: :I 6A  "76@D
->K:G  B<'+ G>BDGD 6C9 &:@:  6C9 HIG:6BH ;GDB
=>C6 4:AADL ->K:G  B<' + 26C< :I 6A  6C9 2JA>
A6@:  B<' + 26C< :I 6A  /=: C>IG>I: >DC 8DC8:CIG6
I>DCH L:G: ADL:G I=6C I=DH: ;GDB HDB: I:BE:G6I: G>K:GH I=: &6GA6 '6@:
 B<' )*) +6E69>B>IG>DJ :I 6A  6C9 I=:
.E:G8=:>DH ->K:G  B<' )*) (6G@D<>6CC> :I 6A
 >C "G::8: I=: "J6M>C9>76 ->K:G  B<' )*)
6C9 I=: $B7J6WJ ->K:G  B<' )*) >C G6O>A <J>6G :I
6A  6C9 I=: 4:AADL ->K:G  B<' )*) 26C< :I
6A  >C =>C6 #DL:K:G I=: C>IG>I: >DCH 8DC8:CIG6I>DCH >C HDB:
2:HI;G>86C G>K:GH L:G: H>B>A6G ID I=: K6AJ:H D; I=: ^I: 9$KD>G:
->K:GH G:;:GG>C< ID I=: LDG@H D; (76N: :I 6A  >C I=: .:C:<6A
->K:G  B<' )*) 6C9 D; #DJHHDJ :I 6A  >C I=:
*JXBX ->K:G :C>C  B<' )*)
/=: C>IG6I: 8DC8:CIG6I>DCH G6C<:H D; I=: DBDX ->K:G
 B<' )*) 6C9 I=: >6 ->K:G  B<' )*)
L:G: <:C:G6AAN ;DJC9 >C I=: H6B: G6C<: 6H I=: G>K:GH D; HDB: I:BE:G6I:
6G:6H "G::8:  B<' )*) (6G@D<>6CC> :I 6A  0.
 B<' )*) (6AA>C :I 6A  *C I=: DI=:G =6C9 C>
IG6I: >DC 8DC8:CIG6I>DCH L:G: =><=:G I=6C BDHI IGDE>86A DC:H HJ8= 6H
I=: "J6M>C9>76 ->K:G >C G6O>A  B<' )*) <J>6G :I 6A
 I=: 4:AADL ->K:G >C =>C6  B<' )*) 26C< :I 6A
 I=: DC<D ->K:G >C -  B<' )*) :H8N :I 6A
 6C9 I=: .:C:<6A ->K:G >C .:C:<6A  B<' )*)
(76N: :I 6A  #DL:K:G I=: (6G6 ->K:G >C &:CN6  B<
' )*) (6H:H: :I 6A  =69 <G:6I:G C>IG6I: >DC 8DC8:CIG6I>DCH
I=6C I=: 6C96B6 ->K:G DC:H  B<' )*)
H ;DG I=: 8=ADGDE=NAAa8DC8:CIG6I>DCH ;GDB I=>H HIJ9N I=:N L:G:
BJ8= =><=:G I=6C I=DH: >C DI=:G G>K:GH >C IGDE>86A 6G:6H "J6M>C9>76
->K:G G6O>A  μ<' <J>6G :I 6A  (6G6 ->K:G &:CN6
 μ<' (6H:H: :I 6A  DC<D ->K:G -  μ<'
:H8N :I 6A  6C9 I=DH: D; I=: G>K:GH >C I:BE:G6I: 6G:6H
.E:G8=:>DH ->K:G "G::8:  μ<' (6G@D<>6CC> :I 6A 
6E: !:6G ->K:G 0.  μ<' (6AA>C :I 6A  /=:H: G:
HJAIH >C9>86I:9 6 HIGDC< EGDA>;:G6I>DC D; 6A<6: >C I=: ^I: 9$KD>G: ->K:GH
0AI>B6I:AN I=: DBDX 6C96B6 6C9 >6 ->K:GH H::B:9 ID 7: HIGDC<AN
>BE68I:9 7N =JB6C 68I>K>IN 6ADC< I=:>G L6I:GH=:9H /=: CJIG>:CI 8DC
8:CIG6I>DCH C>IGD<:CE=DHE=DGJH >C I=: ^I: 9$KD>G: ->K:GH 6G:
6BDC< I=: =><=:HI >C I=: LDGA9 IGDE>86A 6G:6H 6C9 8DCIG>7JI: ID L6I:G
:JIGDE=>86I>DC
4.3. Factors influencing nutrients loads
*C: D; I=: ;68IDGH I=6I >C;AJ:C8: I=: CJIG>:CI 9NC6B>8H 6C9 =N9GDA
D<N D; G>K:GH >H G6>C;6AA 2: =6K: I=JH A>C@:9 I=: IDI6A 8DC8:CIG6I>DCH D;
C>IG>I: >DCH C>IG6I: >DCH 6C9 G:68I>K: E=DHE=DGJH >C I=: DBDX 6C
96B6 6C9 >6 ->K:GH ID I=: 6K:G6<: BDCI=AN EG:8>E>I6I>DC !>< .
/=: E:6@H D; C>IG>I: 8DC8:CIG6I>DCH >C I=: I=G:: G>K:GH 8D>C8>9:9 L>I=
I=: B6M>BJB EG:8>E>I6I>DC >C %JC: -6>CN H:6HDC GN H:6
HDC !ADD9 H:6HDC /=:H: 8DC8:CIG6I>DCH ;:AA H=6GEAN 9JG>C< I=: ;ADD9
H:6HDC >C9>86I>C< C>IG>;>86I>DC EGDBDI:9 7N 768I:G>6A 68I>K>IN 7G:6@>C<
9DLC DG<6C>8 B6II:G J> :I 6A  )>IG6I: A:K:AH L:G: 9:8G:6H>C<
>C I=: L6I:GH L>I= I=: 9GDE >C G6>C;6AA ;GDB %JC: ID *8ID7:G /=:H: A:K

CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
:AH L:G: DC 6K:G6<: =><=:G 9JG>C< I=: 9GN H:6HDC >C I=: G>K:GH L6I:G 7:
86JH: D; I=: ADL L6I:G G:C:L6A :HE:8>6AAN >C I=: JEHIG:6B HI6I>DCH /=:
ADL G6>C;6AA G:8DG9:9 9JG>C< I=: ;ADD9 6C9 9GN H:6HDCH ;6KDG:9 6C >C
8G:6H: >C E=DHE=6I: A:K:AH >C G>K:GH L6I:GH $I H::BH I=6I I=: A:68=>C< :;
;:8I D; HD>AH 9JG>C< I=: G6>CN H:6HDC EGDK>9:9 BDG: 6BBDC>6 8DB
EDJC9H )# /&) 6C9 C>IG6I: )* I=6C E=DHE=6I:H +* /=:
HD>AH AD86I:9 6ADC< I=: G>K:G 76H>CH LDJA9 I=:G:;DG: 7: BDG: :CG>8=:9 >C
C>IGD<:CDJH :A:B:CIH 6C9 LDJA9 >C9>86I: ;G:FJ:CI JH: D; ;:GI>A>O:GH G>8=
>C C>IGD<:C :A:B:CIH 6A6A :I 6A  DB:HI>8 9>H8=6G<:H :HE:
8>6AAN ;GDB 8>I>:H 7DG9:G>C< G>K:GH 6AHD 699:9 ID I=: E=DHE=DGJH 6C9 C>
IGD<:C AD69 >C I=: L6I:GH )>IGD<:C >CEJIH L:G: 9DB>C6CI :HE:8>6AAN
9JG>C< I=: 9GN 6C9 G6>CN H:6HDCH #DL:K:G I=: 9>AJI>DC :;;:8I L6H BDG:
EGDCDJC8:9 ;DG C>IG>I: 6C9 C>IG6I: 8DC8:CIG6I>DCH >C *8ID7:G L=:G:6H
I=: =><=:G ;ADL G6I:H 9JG>C< I=>H E:G>D9 =69 6C >C8G:6H:9 :;;:8I DC E=DH
E=6I: 8DC8:CIG6I>DCH 6H 9:BDCHIG6I:9 7N "6D :I 6A 
!68IDG>6A 6C6ANH>H L6H E:G;DGB:9 L>I= I=: B:6HJG:9 E6G6B:I:GH 6C9
I=: G:HJAIH 6G: EG:H:CI:9 >C /67A:
/=G:: ;68IDGH ! ! 6C9 ! 688DJCI:9 ;DG  D; I=: 8JBJA6
I>K: E:G8:CI6<: D; I=: IDI6A K6G>67>A>IN >C I=: 9GN H:6HDC !68IDG :M
EA6>C:9  D; I=: IDI6A K6G>6C8: L>I= 6C :><:CK6AJ: D;  /=>H
;68IDG H::BH ID =6K: HIGDC< EDH>I>K: AD69>C<H L>I= G6>C;6AA 6C9 IDI6A
&?:A96=A C>IGD<:C /&) 7JI C:<6I>K: AD69>C<H L>I= L6I:G I:BE:G6IJG:
IDI6A 9>HHDAK:9 HDA>9H /. :A:8IG>86A 8DC9J8I>K>IN   H6A>C>IN IDI6A
E=DHE=DGJH /+ 6C9 G>K:G 9>H8=6G<: /=: H:8DC9 ;68IDG 688DJCI:9 ;DG
 D; I=: IDI6A K6G>6C8: L>I= 6C :><:CK6AJ: D;  +DH>I>K: AD69
>C<H L:G: ;DJC9 L>I= E# 6C9 9>HHDAK:9 DMN<:C * !68IDG 8DC
IG>7JI:9 ID  D; I=: IDI6A K6G>6C8: L>I= 6C :><:CK6AJ: D;  6C9
=69 C:<6I>K: AD69>C<H L>I= C>IG6I: /=: G:A6I>DCH=>EH 7:IL::C ;68IDG
E6G6B:I:GH HJ<<:HI I=6I I=: ADL EG:8>E>I6I>DC 699:9 ID I=: ADL ;ADL
G6I: >C I=: 9GN H:6HDC >C9J8:9 6C >C8G:6H: >C I=: /+ 6C9 /&) A:K:AH
!68IDGH 6C9 HJ<<:HI I=6I C>IG6I: >DCH B6>CAN 8DCIGDAA:9 6A<6A 7ADDBH
/=:>G 6K6>A67>A>IN ;DG E=DIDHNCI=:I>8 68I>K>IN L6H 688DBE6C>:9 7N 6
HA><=I >C8G:6H: >C E# 6C9 DMN<:C6I>DC D; I=: 6FJ6I>8 :CK>GDCB:CI
<J>6G :I 6A 
$C I=: G6>CN H:6HDC I=: I=G:: ;68IDGH ! ! 6C9 ! :MEA6>C:9
 D; I=: 8JBJA6I>K: E:G8:CI6<: D; I=: IDI6A K6G>67>A>IN !68IDG
688DJCI:9 ;DG  D; I=: IDI6A K6G>6C8: L>I= 6C :><:CK6AJ: D; 
!68IDG >C9>86I:9 EDH>I>K: AD69>C<H L>I= IDI6A 9>HHDAK:9 HDA>9H /.
:A:8IG>86A 8DC9J8I>K>IN   6C9 H6A>C>IN 7JI C:<6I>K: AD69>C<H L>I= 9>H
HDAK:9 DMN<:C *
/=: H:8DC9 ;68IDG 688DJCI:9 ;DG  D; I=: IDI6A K6G>6C8: L>I= 6C
:><:CK6AJ: D;  !68IDG H=DL:9 6 HIGDC< EDH>I>K: AD69>C< L>I=
E=DHE=6I:H 7JI C:<6I>K: AD69>C<H L>I= G6>C;6AA C>IG6I: >DCH 6C9 G>K:G
;ADL !68IDG G:EG:H:CI:9  D; I=: IDI6A K6G>6C8: L>I= 6C :><:C
K6AJ: D;  6C9 =69 EDH>I>K: AD69>C<H L>I= 6BBDC>JB >DCH 6C9 IDI6A
&?:A96=A C>IGD<:C /=: G:A6I>DCH=>EH 6BDC< E6G6B:I:GH JC9:G ;68IDG
G:;A:8I:9 6 =><= >DC>8 6C9 E6GI>8JA6I: 8=6G<: HDA>9 9:7G>H 6 8DCH:
FJ:C8: D; HD>AH A:68=>C< 9JG>C< =:6KN G6>CH 26I:G DMN<:C6I>DC L6H
HIGDC<AN 6HHD8>6I:9 L>I= I=: IG6CHEDGI D; E6GI>8A:H 6C9 9:7G>H ;GDB
GJCD;; L6I:G ;ADL>C< >CID I=: 6FJ6I>8 :CK>GDCB:CI /=: G:A6I>DCH=>EH
6BDC< E6G6B:I:GH JC9:G ;68IDGH 6C9 HJ<<:HI:9 I=6I EG:8>E>I6I>DCH
6C9 G>K:G 9>H8=6G<:H 6G: I=: B6>C G:<JA6IDGH D; I=: A:K:AH D; CJIG>:CI
7>D6K6>A67>A>IN ;DG 6A<6: E=DHE=6I: 6C9 C>IG6I: >C G>K:GH 9JG>C< I=:
G6>CN H:6HDC "6D :I 6A 
'>@:L>H: I=G:: ;68IDGH 688DJCI>C< ;DG  D; I=: 8JBJA6I>K: E:G
8:CI6<: D; IDI6A K6G>6C8: 8DCIGDAA:9 CJIG>:CI AD69H >C G>K:GH 9JG>C< I=:
;ADD9 H:6HDC !68IDG 688DJCI:9 ;DG  D; I=: IDI6A K6G>6C8: L>I=
6C :><:CK6AJ: D;  6C9 H=DL:9 C:<6I>K: AD69>C<H L>I= IDI6A 9>H
HDAK:9 HDA>9H /. :A:8IG>86A 8DC9J8I>K>IN   H6A>C>IN 6C9 G>K:G 9>H
8=6G<: /=: >DC>8 6C9 HDA>9 8=6G<: >C G>K:G L6I:GH L6H <G:6I:HI 9JG>C<
I=: ;ADD9 H:6HDC 7:86JH: >I 688DJCI:9 ;DG 6AA I=: K6G>6C8: D; I=>H ;68IDG
!68IDG G:EG:H:CI:9  D; I=: IDI6A K6G>6C8: L>I= 6C :><:CK6AJ: D;
 +DH>I>K: 8=6G<:H L:G: ;DJC9 L>I= L6I:G I:BE:G6IJG: C>IG>I: >DCH
6C9 G>K:G 9>H8=6G<: L=>A: EG:8>E>I6I>DC 6C9 C>IG6I: >DCH :M=>7>I:9 C:<6
I>K: 8=6G<:H /=>H HJ<<:HI:9 6 E=:CDB:CDC D; C>IG>;>86I>DC >C9J8:9 7N
I=: G>H>C< G>K:GH L6I:GH !68IDG G:EG:H:CI>C<  D; I=: IDI6A K6G>
6C8: L>I= 6C :><:CK6AJ: D;  <6K: EDH>I>K: 8=6G<:H L>I= 9>HHDAK:9
DMN<:C * 6C9 I=:C C:<6I>K: L>I= DGI=DE=DHE=6I:H /=>H ;68IDG
H=DLH I=6I I=: 6HH>B>A6I>DC D; E=DHE=6I:H 7N 6A<6: 9JG>C< I=: ;ADD9 H:6
HDC L6H 688DBE6C>:9 7N 6C >C8G:6H: >C DMN<:C6I>DC D; I=: 6FJ6I>8 :CK>
GDCB:CI +=DIDHNCI=:I>8 68I>K>IN >C8G:6H:9 I=:G:;DG: 9JG>C< I=>H E:G>D9
77DII :I 6A 
4.4. Sources of the nutrient inputs
/=: =>:G6G8=>86A 6C6ANH>H 9:C9GD<G6BH !>< B69: >I EDHH>7A: ID
>9:CI>;N I=G:: HI6I>HI>86AAN H><C>;>86CI <GDJEH E:G H:6HDC "6 "6 "6
;DG I=: 9GN H:6HDC "7 "7 "7;DG I=: G6>CN H:6HDC 6C9 "8 "8 "8
;DG I=: ;ADD9 H:6HDC
Table 5
/=: EG>C8>E6A 8DBEDC:CI 6C6ANH>H + D; K6G>DJH E6G6B:I:GH HIJ9>:9 >C I=: 9GN G6>CN 6C9 ;ADD9 H:6HDCH
GN H:6HDC -6>CN H:6HDC !ADD9 H:6HDC
! ! ! ! ! ! ! ! !
+AJK>DB:IGN 0.906   0.69   0.64 
/:BE:G6IJG: 0.75    0.59   0.83 
E#  0.90       
/. 0.72   0.95   0.87  
0.79   0.95   0.88  
*  0.78  0.70     0.66
.6A>C>IN 0.78   0.93   0.88  
/+ 0.65        
=Aa        
)#     0.88   
+*0.55    0.74    0.61
/&) 0.84     0.63   
)*  0.73  0.62   0.88 
)*       0.81 
>H8=6G<: 0.86    0.60   0.62 
><:CK6AJ:H         
JBJA6I>K:         
E# =N9GD<:C>DC>8 EDI:CI>6A /. IDI6A 9>HHDAK:9 HDA>9H :A:8IG>86A 8DC9J8I>K>IN * 9>HHDAK:9 DMN<:C /+ IDI6A E=DHE=DGJH =Aa8=ADGDE=NAAa )#6BBDC>JB
>DC +*G:68I>K: E=DHE=DGJH /&) IDI6A &?:A96=A C>IGD<:C )*C>IG6I: >DC )*C>IG>I: >DC
6DA9 K6AJ: G:EG:H:CIH HIGDC< AD69>C<H

CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
Fig. 6. -:HJAIH D; =>:G6G8=>86A 8AJHI:G 6C6ANH>H H=DLC 6H 9:C9GD<G6B ;DG I=: K6G>67A:H HIJ9>:9 >C I=: I=G:: G>K:GH ;DG 6AA H:6HDCH 6GN H:6HDC 7-6>CN H:6HDC 6C9
8!ADD9 H:6HDC
)JIG>:CI 8DC8:CIG6I>DCH >C I=: "6 "7 6C9 "8<GDJEH L:G: B6>CAN
6IIG>7JI67A: ID :MI:GC6A HDJG8:H BDC< I=:H: I=: >C8G:6H: >C 9DB:HI>8
9>H8=6G<:H 6<G>8JAIJG6A HAJGGN 6C9 ;:GI>A>O:G GJCD;; L:G: EGDB>C:CI
'>J 26C< :I 6A  /=: )*6C9 /&) /DI6A &?:A96=A )>
IGD<:C 8DCI:CIH 8DCIG>7JI:9 ID I=: CJIG>:CI :CG>8=B:CI D; I=: 6FJ6I>8
:CK>GDCB:CI 9J: ID I=:>G 6CI=GDED<:C>8 HDJG8:H /=:H: HDJG8:H L:G:
B6>CAN D; 6<G>8JAIJG6A DG><>C HJ8= 6H ;:GI>A>O:G >CEJIH 6C9 ID 6 A:HH:G :M
I:CI JG76C >CEJIH /=>H 8DJA9 7: :MEA6>C:9 7N I=: ;G:FJ:CI EGDM>B>IN D;
EA6CI6I>DCH 6ADC< I=: G>K:G L6I:GH=:9H /=JH C>IG6I: >DCH 6K6>A67>A>IN >C
I=: I=G:: G>K:GH L6I:G >BE68I:9 6A<6: EGDA>;:G6I>DC <J>6G :I 6A 
.J7=6 :I 6A 
)JIG>:CI 8DC8:CIG6I>DCH >C I=: "6 "7 6C9 "8<GDJEH L:G: B6>CAN
9J: ID >CI:GC6A HDJG8:H 26I:G I:BE:G6IJG: 6C9 G>K:GH 9>H8=6G<:H >C;AJ
:C8:9 HIGDC<AN 6FJ6I>8 DG<6C>8 9:8DBEDH>I>DC 6C9 C>IG>I: )* A:K:AH
/=: HDJG8:H D; DGI=DE=DHE=6I:H 6EE:6G:9 ID 7: H:9>B:CI6GN !68IDGH
HJ8= 6H E=DHE=DGJH E6GI>8A:H 69HDGEI>DC9:HDGEI>DC 6C9 CJIG>:CIH G:
A:6H:9 ;GDB H:9>B:CIH H=DJA9 7: 8DCH>9:G:9 '>J  ADL G:C:L6A
D; L6I:GH 6C9 ADL ;ADL G6I:H 688:CIJ6I:9 I=: >CDG<6C>8 E=DHE=DGJH
;G68I>DC +* 6K6>A67>A>IN 6C9 8DCIG>7JI:9 ID G>K:GH :JIGDE=>86I>DC
'> :I 6A  /=: =><= DG<6C>8 E=DHE=DGJH 8DCI:CI G:EG:H:CI>C< JE
ID  D; IDI6A E=DHE=DGJH >C I=: G>K:GH L6I:G 8DJA9 7: 9:EDH>I:9 6I
I=: 7DIIDB 6C9 ;DGB 6C >BEDGI6CI G:H:GKD>G D; E=DHE=DGJH >C I=: H:9>
B:CIH DJ@:B6G6 :I 6A *G>=:A :I 6A 
)JIG>:CIH 8DC8:CIG6I>DCH >C I=: "6 "7 6C9 "8<GDJEH L:G:
B6>CAN 6IIG>7JI67A: ID :MI:GC6A HDJG8:H BDC< I=:H: I=: A:68=>C< D;
HD>AH 6ADC< I=: G>K:GH 86I8=B:CIH 6C9 6<G>8JAIJG6A :GDH>DC 8DCHI>IJI:9 6
EG:EDC9:G6CI EA68: ': )DZ :I 6A  +AJK>DB:IGN ;6KDG:9 HD>AH
A:68=>C< :CG>8=:9 L>I= ;:GI>A>O:GH C>IGD<:C 6C9 E=DHE=6I: 6ADC< I=:
G>K:GH L6I:GH=:9 6<G>8JAIJG6A GJCD;; 6C9 C6IJG6A :GDH>DC 'DE:H :I 6A
 $CI:CH>K: :MEDGI 8GDEH 8D8D6 GJ77:G 8D;;:: E6AB D>A :I8 C:6G
G>K:GH 76H>CH G:FJ>G>C< A6G<: >CEJIH D; ;:GI>A>O:GH ;DG D7K>DJH N>:A9
C::9H AD69:9 I=: HD>AH L>I= E=DHE=DGJH 6C9 C>IGD<:C L=>8= L:G: I=:C
A:68=:9 7N B:I:DG>I: 9G6>C6<: L6I:GH (8&:G<DL :I 6A 
16CA6JL: :I 6A  !JGI=:GBDG: EG:8>E>I6I>DC HIGDC<AN 6;;:8I:9 I=:
E=DHE=DGJH >CEJIH /+ +* ID I=: 6FJ6I>8 :CK>GDCB:CI HJ<<:HI>C<
I=6I 6A<6: <GDLI= L6H B6>CAN 8DCIGDAA:9 7N I=>H CJIG>:CI 9JG>C< G6>CN
E:G>D9H ': )DZ :I 6A 
(DG:DK:G I=: =><= >DC>8 AD69   /. H6A>C>IN G:;A:8I:9 H><C>;>
86CI 6CI=GDED<:C>8 >CEJIH JG76C 9>H8=6G<:H ID I=: 6FJ6I>8 :CK>GDC
B:CI AJHI:G 6C6ANH>H !>< GN HJ<<:HIH I=6I C>IG6I: >DCH B6>CAN 8DC
IGDAA:9 6A<6A EGDA>;:G6I>DC 6C9 8DCIG>7JI:9 7N >IH 9>;;JH: HDJG8:H L>I=
E=DHE=6I: ID I=: >DC>8 8=6G<: D; I=: G>K:GH -:A6I>DCH 6BDC< E6G6B:I:GH
JC9:G ;68IDGH 6C9 HJ<<:HI I=6I C>IG6I: 8DCHJBEI>DC 7N 6A<6: ;DG
<GDLI= L6H 688DBE6C>:9 7N 6C >C8G:6H: >C E# 6C9 DMN<:C6I>DC D; I=:
6FJ6I>8 :CK>GDCB:CI G:A6I:9 ID E=DIDHNCI=:H>H 68I>K>IN
4.5. Water quality of rivers
2: :K6AJ6I:9 I=: L6I:G FJ6A>IN D; I=: DBDX 6C96B6 6C9 >6
->K:GH 688DG9>C< ID I=: 8A6HH>;>86I>DC :HI67A>H=:9 7N I=: *)( G:HD
AJI>DC  ;DG I=: ;G:H=L6I:G FJ6A>IN 8A6HH  8A6HH  6C9 8A6HH 
JC=6 :I 6A 7 /=: G:HJAIH HJ<<:HI:9 I=6I I=: L6I:G FJ6A>IN D;
I=: DBDX ->K:G L6H >C 8A6HH  <:C:G6AAN >CI:C9:9 ;DG =JB6C 8DCHJBE
I>DC 6;I:G 69K6C8:9 IG:6IB:CI (DG: I=: L6I:G FJ6A>IN D; I=: 6C96B6
6C9 >6 ->K:GH L6H >C 8A6HH  <:C:G6AAN >CI:C9:9 ;DG =JB6C 8DCHJBE
I>DC 6;I:G 8DCK:CI>DC6A IG:6IB:CI /67A:  /=:H: L6I:GH 86C 6AHD 7:
JH:9 ;DG 8GDE >GG><6I>DC =D77N>HI ;>H=>C< H:8DC96GN 8DCI68I G:8G:6I>DC
6C9 6C>B6AH 8DCHJBEI>DC
/=: L6I:G FJ6A>IN D; I=: DBDX 6C96B6 6C9 >6 ->K:GH L6H 6AHD
6HH:HH:9 7N I=: 26I:G ,J6A>IN $C9:M 2,$ EGDEDH:9 7N +:H8: 6C9
2JC9:GA>C  !>< . <>K:H I=: 2,$ K6AJ:H D; :68= HI6I>DC 9JG>C<
I=: 9GN G6>CN 6C9 ;ADD9 H:6HDCH /=:H: K6AJ:H G6C<:9 ;GDB  ID 
9JG>C< I=: 9GN H:6HDC ;GDB  ID  9JG>C< I=: G6>CN H:6HDC 6C9 ;GDB
 ID  9JG>C< I=: ;ADD9 H:6HDC 88DG9>C< ID I=: 8A6HH>;>86I>DC EGD

CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
Table 6
HH:HHB:CI D; I=: L6I:G FJ6A>IN D; I=: DBDX 6C96B6 6C9 >6 ->K:GH 688DG9>C< ID *)( G:HDAJI>DC  ;DG I=: ;G:H=L6I:G FJ6A>IN 8A6HH>;>86I>DC
A6HH:H /G:6IB:CI 7:;DG: 8DCHJBEI>DC E# * B<' /. B<' )*B<' )*) /) B<' ) /+ B<' + =Aaμ<'
6DC8:CIG6I>DCH A>B>IH :HI67A>H=:9 7N *)(  ;DG I=: ;G:H=L6I:G FJ6A>IN 8A6HH>;>86I>DC JC=6 :I 6A 7
A6HH .>BEA>;>:9     ;DG E#   
A6HH DCK:CI>DC6A     ;DG E#   
A6HH 9K6C8:9     ;DG E#   
A6HH:H /G:6IB:CI 7:;DG: 8DCHJBEI>DC ->K:G E# * B<' /. B<' )*B<' )*) /) B<' ) /+ B<' + =Aaμ<'
K:G6<: 8DC8:CIG6I>DCH D; E6G6B:I:GH >C H6BEA:9 H>I:H ;GDB (6G8=  ID (6G8= 
Class 3 9K6C8:9 Comoé       
Class 2 DCK:CI>DC6A Bandama       
Class 2 DCK:CI>DC6A Bia       
E# =N9GD<:C>DC>8 EDI:CI>6A /. IDI6A 9>HHDAK:9 HDA>9H )*C>IG6I: >DC /) IDI6A C>IGD<:C /+ IDI6A E=DHE=DGJH =Aa8=ADGDE=NAAa
6 M8:EI ;DG 9>HHDAK:9 DMN<:C * I=: 8DC8:CIG6I>DC A>B>IH 6G: I=: B>C>BJB K6AJ:H
EDH:9 7N 2J :I 6A  I=: L6I:G FJ6A>IN D; 6AA I=: HI6I>DCH 86C 7:
8DCH>9:G:9 <DD9  2,$  -:HJAIH EG:H:CI:9 DC !>< . H=DL
6AA I=: 2,$ >C9:M K6AJ:H D; I=: G>K:GH 7:NDC9  H:: G:9 A>C: DC !><
. ">K:C I=: ILD L6I:G FJ6A>IN 6HH:HHB:CI B:I=D9H >I 6EE:6GH I=6I
G>K:GH L6I:GH JH:9 7N I=: >C9><:CDJH GJG6A EDEJA6I>DCH L>I=DJI 69
K6C8:9 EG>DG IG:6IB:CI 8DJA9 8DCHI>IJI: 6 =JB6C =:6AI= G>H@
(DG:DK:G I=: 2,$ >C9:M EGDEDH:9 7N +:H8: 6C9 2JC9:GA>C 
9D:H CDI I6@: >CID 688DJCI I=: 8DCI:CIH D; 8=ADGDE=NAAa B:I6AoidH
6C9 E:HI>8>9:H I=6I 6;;:8I I=: L6I:G FJ6A>IN D; I=:H: G>K:GH !DG :M6BEA:
*J6II6G6 :I 6A  ;DJC9 I=6I 9JG>C< I=: ;ADD9 H:6HDC  6C9
 D; I=: L6I:G H6BEA:H ;GDB I=: DBDX 6C9 >6 ->K:GH G:HE:8
I>K:AN =69 6GH:C>8 8DC8:CIG6I>DCH 67DK: I=: 2#* G:8DBB:C96I>DC
 μ<'
$CK:HI><6I>DCH >C I=: )O> IG>7JI6GN D; I=: 6C96B6 ->K:G G:K:6A:9
8A6C9:HI>C: 6GI>H6C6A <DA9 B>C>C< L=>8= >C:MDG67AN 9:<G69:H I=: L6I:G
FJ6A>IN D; I=>H G>K:G /=: K>9:D I>IA:9 $AA:<6A <DA9 E6CC>C< I=G:6I:CH I=:
;>H=:GN G:HDJG8:H D; I=: )5> ->K:G>H 6C >AAJHIG6I>DC =IIEH
L:7;68:7DD@8DB-/$>C;DK>9:DH -/$ $C;D
 (DG:DK:G BDHI D; I=: AD86A 8DBBJC>I>:H JH: I=: L6I:G ;GDB
I=:H: G>K:GH ;DG 9G>C@>C< L6H=>C< 6C9 8DD@>C< L>I=DJI 6CN EG>DG IG:6I
B:CI /=: =:6AI= D; 6I A:6HI B>AA>DC E:DEA: >C I=: .DJI= 6HI D; ^I:
9$KD>G: >H I=:G:;DG: I=G:6I:C:9 $C 8DBE6G>HDC L>I= I=: G:HJAIH D; /67A:
I=: 2,$ >C9:M K6AJ:H D7I6>C:9 L:G: CDI HJ;;>8>:CIAN G:EG:H:CI6I>K: D;
I=: EDAAJI>DC HI6IJH D; I=: DBDX 6C96B6 6C9 >6 ->K:GH /6@>C< >CID
688DJCI I=: 8=ADGDE=NAAa6C9 B:I6AoidH 8DCI:CIH >C I=: 2,$ >C9:M
86A8JA6I>DC LDJA9 6AADL 6 7:II:G 6HH:HHB:CI D; I=: L6I:G FJ6A>IN D;
I=:H: G>K:GH
4.6. Eutrophication assessment in rivers
4.6.1. Chl-a classification and limiting factors
JIGDE=>86I>DC 6HH:HHB:CI D; G>K:G L6I:GH >C ^I: 9$KD>G: =6H 7:
8DB: :HH:CI>6A <>K:C I=: 8=6AA:C<:H D; JH: B6C6<:B:CI 6C9 9G>C@>C<
L6I:G AI=DJ<= B6CN B:I=D9H =6K: 7::C 9:K:ADE:9 ;DG 6HH:HH>C< 6C9
BDC>IDG>C< :JIGDE=>86I>DC IG:C9H L: JH:9 I=: 8A6HH>;>86I>DC H8=:B: ;DG
=Aa7>DB6HH   /=: L6I:G FJ6A>IN D; I=: DBDX 6C96B6
6C9 >6 ->K:GH L6H BDHI D;I:C JC9:G I=: B:HDIGDE=>8 HI6I: 9JG>C< I=:
I=G:: H:6HDCH !>< 6
/D >9:CI>;N I=: EG>C8>E6A A>B>I>C< ;68IDG D; 6A<6A 7ADDBH >C I=: HNH
I:B L: JH:9 I=: )+ B6HH G6I>D EG:H:CI:9 >C !>< 7 B6HH G6I>D D;
)+ ADL:G I=6C  >C9>86I:H I=6I ) >H I=: A>B>I>C< ;68IDG ;DG 6A<6A
<GDLI= L=>A: 6 G6I>D =><=:G I=6C  H=DLH I=6I + >H I=: @:N :A:B:CI
-:9;>:A9 :I 6A 
*K:G I=: H6BEA>C< 86BE6><CH 6AA I=: L6I:GH L:G: >C 6 =NE:G:J
IGDE=>8 HI6I: 6C9 >C <:C:G6A C>IGD<:C L6H I=: A>B>I>C< CJIG>:CI 9JG>C<
I=: ;ADD9 E:G>D9 6C 6K:G6<: D; )+ P   -:9;>:A9 :I 6A 
/=: HIGDC< ;ADD9H D; I=: G>K:GH H::B:9 ID ;6KDG I=: E=DHE=6I: :CG>8=
B:CI D; I=: L6I:GH ID I=: 9:IG>B:CI D; C>IG6I: >DCH 6H H=DLC >C !>< .
/=>H :MEA6>CH I=: ADL 6K:G6<: K6AJ:H D; I=: )+ G6I>D 9JG>C< I=>H E:G>D9
+=DHE=DGJH DC I=: DI=:G =6C9 A>B>I:9 E=NIDEA6C@IDC EGD9J8I>DC >C 6
I=>G9 D; I=: H6BEA>C< HI6I>DCH >C (6G8= 9GN H:6HDC 6C9 >C I=: ILD
I=>G9H >C %JC: G6>CN H:6HDC /=: DBDX ->K:G >C I=>H 86H: =69 =><=
)+ K6AJ:H 9JG>C< I=: 9GN 6C9 G6>CN H:6HDCH /=:H: ILD H:6HDCH H=DL:9
I=: =><=:HI A:K:AH D; C>IG6I: >C I=: DBDX ->K:G /=: =><= 6K6>A67>A>IN D;
C>IGD<:C JG76C L6HI: A:68=>C< D; HD>AH :CG>8=:9 L>I= ;:GI>A>O:GH EGD76
Fig. 7. .:6HDC6A K6G>6I>DCH D; I=: IGDE=>8 HI6IJH 6 6C9 I=: )+ B6HH G6I>DH 7 >C I=: DBDX 6C96B6 6C9 >6 ->K:GH 9JG>C< (6G8=  ID (6G8=  E:G>D9H
/=: G:9 96H=:9 A>C: 9:A>C:6I:H I=: 8DC8:CIG6I>DC G6C<:H D; I=: IGDE=>8 HI6IJH !>< 6 6C9 I=: A>B>I>C< ;68IDG ;DG 6A<6A <GDLI= !>< 7 "G6N 8DADG EG:H:CIH I=: 9GN H:6
HDCH L=>I: 8DADG EG:H:CIH I=: G6>CN H:6HDCH 6C9 7A68@ 8DADG EG:H:CIH I=: ;ADD9 H:6HDCH !DG >CI:GEG:I6I>DC D; I=: G:;:G:C8:H ID 8DADG >C I=>H ;><JG: A:<:C9 I=: G:69:G >H
G:;:GG:9 ID I=: L:7 K:GH>DC D; I=>H 6GI>8A:

CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
7AN =:AE:9 ID A>B>I E=DHE=DGJH >C I=: DBDX ->K:G 9JG>C< I=: 9GN 6C9
G6>CN H:6HDCH +=DHE=DGJH >H I=: ;68IDG A>B>I>C< :JIGDE=>86I>DC 9JG>C<
I=: ADL L6I:G E:G>D9 9GN H:6HDC 9J: ID I=: HADLC:HH D; L6I:G G:
C:L6A $I L6H HDB:I>B:H D7H:GK:9 I=6I I=: DBDX ->K:G =69 9G>:9 JE >C
I=: HI6I>DCH JEHIG:6B 2: BJHI CDI 6AHD C:<A:8I I=: L6I:GH:9>B:CI :M
8=6C<:H ;6KDG:9 7N 8:GI6>C HE:8>;>8 8DC9>I>DCH D; I=: 6FJ6I>8 :CK>GDC
B:CI 688DG9>C< ID I=: 7>D<:D8=:B>86A 8N8A: D; I=>H CJIG>:CI 26C< 6C9
'>6C< 
) L6H I=: A:6HI 6K6>A67A: CJIG>:CI >C I=: 6C96B6 ->K:G 9JG>C< 
6K:G6<: )+  !>< 7 $C 8DCIG6HI + 7:86B: I=: A:HH 6K6>A67A:
CJIG>:CI >C I=: 6FJ6I>8 :CK>GDCB:CI I=: C:MI N:6G :HE:8>6AAN 9JG>C< I=:
E:G>D9 D; G>H>C< L6I:G %JC ID )DK !>< 7 /=:G: L6H I=JH 6
H=>;I D; 6A<6A 7ADDB A>B>I6I>DC ;GDB C>IGD<:C >C  ID E=DHE=DGJH >C
 /=: 6C96B6 ->K:G L6I:GH L:G: HJ7?:8I ID 8DBE:I>I>K: >CEJIH D;
) 6C9 + 9JG>C< I=: =N9GDAD<>86A H:6HDCH /=>H H>IJ6I>DC >H FJ>I: G:6HDC
67A: 8DCH>9:G>C< I=6I 6GDJC9 I=: G>K:G L6I:GH=:9H 6G: JG76C 6G:6H 6C9
BDG: 8GDEA6C9H I=6I 9>H8=6G<: C>IGD<:C 6C9 E=DHE=DGJH >CID I=: L6I:GH
A:69>C< ID I=: :JIGDE=>86I>DC D; I=:H: C6IJG6A :8DHNHI:BH !68=GJA :I
6A 
DC8:GC>C< I=: >6 ->K:G C>IGD<:C H::B:9 ID 7: I=: A:6HI 6K6>A67A:
:A:B:CI >C I=: 6FJ6I>8 :CK>GDCB:CI 9JG>C< I=: 9GN 6C9 G6>CN H:6HDCH
8:GI6>CAN I=: BDHI 8DCHJB:9 7N 6A<6: 'DL )+ K6AJ:H P L:G:
G:8DG9:9 >C %JC: L=>8= 8D>C8>9:9 L>I= I=: =><= 8=ADGDE=NAAa=Aa
8DC8:CIG6I>DCH >C I=: L6I:G 8DAJBC G:A6I>K:AN ADL )+ G6I>D =69 7::C
G:EDGI:9 ID 7: 6HHD8>6I:9 L>I= I=: 9>G:8I 6C9 >C9>G:8I :;;:8IH D; :JIGDE=
>86I>DC +6KA>9DJ :I 6A 46AWhC :I 6A 
Fig. 8. .:6HDC6A K6G>6I>DCH D; I=: /.$IHG >C9:M >C I=: DBDX 6C96B6 6C9 >6
->K:GH 9JG>C< (6G8=  ID (6G8=  E:G>D9H /=: G:9 96H=:9 A>C: 9:A>C
:6I:H I=: G6C<:H D; I=: IGDE=>8 HI6IJH !DG >CI:GEG:I6I>DC D; I=: G:;:G:C8:H ID
8DADG >C I=>H ;><JG: A:<:C9 I=: G:69:G >H G:;:GG:9 ID I=: L:7 K:GH>DC D; I=>H 6GI>
8A:
4.6.2. The trophic state index (TSItsr)
/:BE:G6I: 6C9 IGDE>86AHJ7IGDE>86A 6FJ6I>8 HNHI:BH =6K: HE:8>;>8
H:CH>I>K>I>:H ID :JIGDE=>86I>DC 9J: ID 9>;;:G:CI >C;AJ:C8:H G:A6I:9 ID 8A>
B6I:H 6C9 A6C9 JH: H=>;IH #JHO6G :I 6A *GI>O%>BXC:O :I 6A
 #><= G6>C;6AA 6C9 I:BE:G6IJG:H B6@: I=: IGDE=>8 HI6IJH EG:9>8
I>DC >C IGDE>86AHJ7IGDE>86A ;G:H=L6I:G BDG: 8DBEA:M /=:N >C9J8:
HDA>9 B6II:G >CIGJH>DCH 86JH:9 7N L6I:GH=:9 :GDH>DC BDG: :CK>GDCB:C
I6A 8DCHIG6>CIH 8DCIGDAA>C< CJIG>:CI 9NC6B>8H 6C9 I=: E=NIDEA6C@IDC G:
HEDCH:H >C L6I:G B6HH:H /GDE=>8 HI6I: >C9>8:H EGDK>9: 8AJ:H 6H ID =DL
CJIG>:CI 6K6>A67>A>IN 6C9 A><=I 8DCIGDA E=NIDEA6C@IDC 9:K:ADEB:CI /=:
/.$IHG >C9:M 9:K:ADE:9 7N JC=6 :I 6A 6 ;DG IGDE>86AHJ7IGDE>86A
HNHI:BH L6H I=JH JH:9 ID 6HH:HH I=: IGDE=>8 HI6I: D; I=: DBDX 6C
96B6 6C9 >6 ->K:GH -:HJAIH DC !>< H=DL:9 I=6I I=GDJ<=DJI I=:
H6BEA>C< E:G>D9 6AA I=: HI6I>DCH L:G: 8DCH>9:G:9 =NE:G:JIGDE=>8 L>I=
CD 9>;;:G:C8: >C :MEG:HH>DC 7:IL::C I=: N:6GH /=>H 86C >C9>86I: 6CI=GD
ED<:C>8 >CEJIH B6>CAN I=GDJ<= 6<G>8JAIJG6A GJCD;; 6C9 9DB:HI>8
H:L6<: 6H H=DLC 7N <J>6G :I 6A  /=: IGDE=>8 HI6I: D; I=: D
BDX 6C96B6 6C9 >6 G>K:GH 688DG9>C< ID I=: /.$IHG >C9:M >H I=:G:;DG:
8DC<GJ:CI L>I= I=: =Aa8A6HH>;>86I>DC /=: /.$IHG >C9:M >H EGDK>C< ID 7:
6 JH:;JA IDDA >C BDC>IDG>C< :JIGDE=>86I>DC >C IGDE>86A G>K:GH
4.7. N and P fluxes
2: 86A8JA6I:9 C>IGD<:C 6C9 E=DHE=DGJH ;AJM:H >: I=: EGD9J8I D;
CJIG>:CI B:6C 8DCI:CI B<' 6C9 I=: BDCI=AN G>K:GH 9>H8=6G<: BH
:M8=6C<:9 7N I=: DBDX 6C96B6 6C9 >6 ->K:GH >C I=: HJG;68: A6N:G
 B ;DG 6AA I=: H>I:H >C (6G8= %JC: 6C9 *8ID7:G ;GDB  ID
 /67A:  /=: CJIG>:CI ;AJM K6AJ:H G6C<:9 ;GDB  ID  < H
;DG C>IG6I: >DCH ;GDB  ID  < H;DG E=DHE=6I: 6C9 ;GDB  ID
 < H;DG C>IG>I: >DCH /=: CJIG>:CI ;AJM:H H=DL:9 D7K>DJH ;AJ8IJ6
I>DCH /=: )*1 HI6I>HI>86A 6C6ANH>H I:HIH G:K:6A:9 H><C>;>86CI 9>;;:G
:C8:H >C E=DHE=6I: 6C9 C>IG6I: >DC ;AJM:H 7:IL::C I=: ;ADD9 6C9 9GN H:6
HDCH DC I=: DC: =6C9 >C I=: DBDX 6C9 6C96B6 ->K:GH 6C9 7:IL::C
I=: ;ADD9 6C9 G6>CN H:6HDCH DC I=: DI=:G >C I=: DBDX ->K:G p 
!JGI=:GBDG: I=:H: ;AJM:H L:G: :FJ>K6A:CI 9JG>C< I=: 9GN 6C9 G6>CN H:6
HDCH >C I=:H: G>K:GH p  DCIG>7JI>DCH ID 6FJ6I>8 :CK>GDCB:CIH
G:A6I:9 ID =JB6C 68I>K>I>:H >C8G:6H:9 H><C>;>86CIAN L>I= G>H>C< L6I:G A:K
:AH 46AWhC :I 6A  +=DHE=DGJH 6C9 C>IGD<:C ;AJM:H L:G: G:A6I:9 ID
;AJ8IJ6I>C< GJCD;; 6ADC< I=: G>K:G 86I8=B:CIH 2J :I 6A  /=:
E=DHE=DGJH >C;AJM L6H BDG: >BEDGI6CI 7:86JH: I=>H ;ADD9 E:G>D9 L6H
B6G@:9 7N 6 A>B>I6I>DC D; C>IGD<:C 99:9 ID I=>H =><=:G 9>HHDAK:9 DMN
<:C K6AJ:H 9JG>C< I=: ;ADD9 H:6HDC  B<' DC 6K:G6<: B6N G:;A:8I
6C >C8G:6H: >C E=NIDEA6C@IDC 68I>K>IN 6C9 I=JH G>K:GH :JIGDE=>86I>DC
(6G@D<>6CC> :I 6A  )>IG>I: >DC ;AJM:H L:G: :FJ>K6A:CI 9JG>C<
I=: =N9GDAD<>86A H:6HDCH D; I=: 6C96B6 6C9 >6 ->K:GH p  $I
H::BH I=6I C:>I=:G I=: ADL L6I:G E:G>D9 CDG :K:C G6>C;6AA >CEJIH =69 6
H><C>;>86CI >BE68I DC I=: C>IG>I: >DCH 9NC6B>8H >C I=:H: ILD G>K:GH !><
.
#DL:K:G ADL C>IG>I: >DCH A:K:AH 9JG>C< I=: ;ADD9 H:6HDCH !>< .
HJ<<:HI:9 =><=:G C>IG>;>86I>DC L>I= G>H>C< L6I:G 6H 6:GD7>8 8DC9>I>DCH
Table 7
)>IG6I: >DCH )* G:68I>K: E=DHE=DGJH +* 6C9 C>IG>I: >DCH )* ;AJM:H >C I=: DBDX 6C96B6 6C9 >6 ->K:GH
G:6 GN H:6HDC -6>CN H:6HDC !ADD9 H:6HDC
)*;AJM
<fH
+*;AJM
<fH
)*;AJM
<fH
)*;AJM
<fH
+*;AJM
<fH
)*;AJM
<fH
)*;AJM
<fH
+*;AJM
<fH
)*;AJM
<fH
C>6HHJX *         
(6CO6C *         
A:E: *         
6;X86D          
)O>          
/>6HH6AX          
>6CDJ6 $         
N6BX $         
7D>HHD $         

CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
* B<' L:G: B:I 6D :I 6A  EDGI>DC D; C>IG>I: >DCH
L6H 8DCK:GI:9 ID 6BBDC>JB 6C9 C>IG6I: >DCH 6C9 8DCIG>7JI:9 ID >C
8G:6H>C< I=: E=DIDHNCI=:I>8 EGD8:HH >C I=: 6C96B6 6C9 >6 ->K:GH /=:
C>IG>;>86I>DC EGD8:HH >C9J8:9 I=: BDG: DG A:HH G6E>9 IG6CH;DGB6I>DC D;
C>IG>I: ID C>IG6I: >DCH >C I=: 6FJ6I>8 :CK>GDCB:CI 2J :I 6A 
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IGJH>DCH D; :CG>8=:9 L6I:GH G:HJAI>C< ;GDB I=: =:6KN G6>C;6AA >C %JC:
L=:C C>IG>I: >DCH A:K:AH L:G: =><= )JIG>:CIH ;AJM:H D7H:GK:9 >C I=: >6
->K:G L:G: A>C@:9 ID >IH E6GI>8JA6G =N9GDAD<>86A G:<>B: L>I= ILD :FJ>K6
A:CI ;ADD9 E:6@H %JAN 6C9 *8ID7:G 6C9 >IH ILD 96BH N6BX 6C9 
*CAN E=DHE=DGJH ;AJM:H K6G>:9 9JG>C< I=: =N9GDAD<>86A H:6HDCH D; I=:
>6 ->K:G L=>8= >C9>86I:9 6 L6I:GH=:9 HJ7?:8I ID 6 H><C>;>86CI >C;AJM D;
I=>H :A:B:CI p  /=>H L6H 8DGGD7DG6I:9 7N I=: <G:6I:G E=DH
E=6I: 6K6>A67>A>IN 9JG>C< I=: 9GN 6C9 ;ADD9 H:6HDCH E:6@H >C !>< .
)JIG>:CI >CI6@:H =6K: 7::C >C;AJ:C8:9 7N I=: 6EEA>86I>DC D; 6<G>8JAIJG6A
E=DHE=6I: ;:GI>A>O:GH 6C9 JG76C >CEJIH 46AWhC :I 6A  $C BDHI
86H:H E=DHE=DGJH 6C9 C>IGD<:C ;AJM:H L:G: G:A6I:9 ID A:68=>C< G>K:G
86I8=B:CIH 6C9 L:G: H><C>;>86CI HDJG8:H D; CJIG>:CIH ID I=: IA6CI>8
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5. Conclusions
(DC>IDG>C< I=: :JIGDE=>86I>DC HI6I: D; G>K:G L6I:GH >C ^I: 9$KD>G:
G:EG:H:CIH 6 B6?DG 8=6AA:C<: ;DG A:69:GH 7:86JH: I=:H: G>K:GH 6G: K>I6A
;DG EDEJA6I>DCH A>K:A>=DD9H /=>H HIJ9N B69: >I EDHH>7A: ID 6HH:HH I=:
L6I:G :JIGDE=>86I>DC D; I=: DBDX 6C96B6 6C9 >6 ->K:GH >BE68I:9
7N =JB6C 68I>K>I>:H 6<G>8JAIJG6A 6C9 JG76C $I :B:G<:H I=6I CJIG>:CI
)+ 8DCI6B>C6I>DCH D; G>K:GH 6G: :HH:CI>6AAN A>C@:9 ID >CI:GC6A H:9>
B:CI >CEJIH 9JG>C< I=: 9GN H:6HDC 6C9 ID G6>C;6AA >CEJIH 9JG>C< I=: G>H
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(DG:DK:G I=: 8=ADGDE=NAAa9NC6B>8H H=DL:9 =><=:G A:K:AH 6I I=:
BDJI=H D; I=: I=G:: G>K:GH 9JG>C< I=: I=G:: H:6HDCH 6H L:AA 6H JEHIG:6B
9JG>C< I=: G6>CN H:6HDC #><= 8=ADGDE=NAAa8DC8:CIG6I>DCH >C G>K:GH
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E=DHE=DGJH C>IGD<:C B6>CAN ;GDB H:9>B:CIH CJB:GDJH 9>H8=6G<:H
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=><= 6K6>A67>A>IN D; DGI=DE=DHE=6I:H 6C9 C>IG6I: >DCH 9JG>C< I=>H E:G>D9
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A:6H: D; E=DHE=DGJH 6C9 C>IGD<:C ;GDB I=: H:9>B:CIH 6C9 I=: ADL G:
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;GDB H:9>B:CIH !JGI=:GBDG: CJIG>:CI >CEJIH ID G>K:GH 9JG>C< G>H>C<
L6I:GH E:G>D9H L:G: B6>CAN 9J: ID :MI:GC6A HDJG8:H D; L=>8= A:68=>C<
D; HD>AH 6ADC< G>K:G L6I:GH=:9H 6C9 6<G>8JAIJG6A :GDH>DC L:G: I6@:C EG>
B6GN >BEDGI6C8: /=: >CI:CH>K: :MEDGI 8GDEH 8D8D6 GJ77:G 8D;;::
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K>DJH N>:A9 C::9H AD69:9 I=: HD>AH L>I= E=DHE=DGJH 6C9 C>IGD<:C /=JH
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6C9 E=DHE=6I:H 6ADC< I=: G>K:G 86I8=B:CIH L>I= 6<G>8JAIJG6A GJCD;;
6C9 C6IJG6A :GDH>DC H 6 G:HJAI I=: 8=ADGDE=NAAaK6AJ:H >C8G:6H:9 L>I=
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6C9 I=:C G:68=:9 I=: =NE:G:JIGDE=>8 HI6IJH 9JG>C< I=: ;ADD9 H:6HDCH
/=: DBDX 6C96B6 6C9 >6 ->K:GH L:G: HIGDC<AN >BE68I:9 7N =J
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8DJA9 8DCHI>IJI: 6 G:6A =:6AI= G>H@
CRediT authorship contribution statement
Maley-Pacôme Soro: DC8:EIJ6A>O6I>DC (:I=D9DAD<N 6I6 8JG6
I>DC !DGB6A 6C6ANH>H !JC9>C< 68FJ>H>I>DC $CK:HI><6I>DC (:I=D9DA
D<N -:HDJG8:H 16A>96I>DC 2G>I>C< DG><>C6A 9G6;I 2G>I>C< G:K>:L
:9>I>C< Koffi Martin N'goran: 6I6 8JG6I>DC !DGB6A 6C6ANH>H 2G>I
>C< DG><>C6A 9G6;I Ahmed Abauriet Ouattara: 6I6 8JG6I>DC !DGB6A
6C6ANH>H 2G>I>C< DG><>C6A 9G6;I Koffi Marcellin Yao: 6I6 8JG6I>DC
2G>I>C< DG><>C6A 9G6;I EG:E6G6I>DC $CK:HI><6I>DC (:I=D9DAD<N +GD
?:8I 69B>C>HIG6I>DC .JE:GK>H>DC 16A>96I>DC G:K>:L :9>I>C< N'Gues-
san Louis Berenger Kouassi: 6I6 8JG6I>DC !DGB6A 6C6ANH>H 1>HJ6A
>O6I>DC $CK:HI><6I>DC Thomas Diaco: .JE:GK>H>DC 2G>I>C< G:K>:L
:9>I>C<
Declaration of competing interest
/=: 6JI=DGH 9:8A6G: I=6I I=:N =6K: CD @CDLC 8DBE:I>C< ;>C6C8>6A
>CI:G:HIH DG E:GHDC6A G:A6I>DCH=>EH I=6I 8DJA9 =6K: 6EE:6G:9 ID >C;AJ
:C8: I=: LDG@ G:EDGI:9 >C I=>H E6E:G
Data availability
6I6 L>AA 7: B69: 6K6>A67A: DC G:FJ:HI
Acknowledgments
/=: 6JI=DGH 6G: I=6C@;JA ID I=: >G:8IDG D; :CIG: 9: -:8=:G8=:H
*8X6CDAD<>FJ:H -* ;DG =>H :C8DJG6<:B:CI 6C9 HJEEDGI .E:8>6A
I=6C@H 6G: :MEG:HH:9 ID I=: G:K>:L:GH ;DG I=:>G 8G>I>86A 8DCIG>7JI>DC
Appendix A. Supplementary data
.JEEA:B:CI6GN 96I6 ID I=>H 6GI>8A: 86C 7: ;DJC9 DCA>C: 6I =IIEH
9D>DG<?B6GEDA7JA
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77DII 2 (D6I6G ! "6JI=>:G * !DK:I * CID>C: 1 -6<J:C:6J * 
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L::@AN 8>I>O:C H8>:C8: >C !G6C8: .8> /DI6A CK>GDC  
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
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
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
CORRECTED PROOF
M.-P. Soro et al. Marine Pollution Bulletin xxx (xxxx) 114391
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... This might be explained by the application of fertilizers in the agricultural area surrounding Mirim Lagoon, indicating that crop drainage water is possibly carrying fertilizers and contaminating the lagoon, mainly at sites P6, P8, P9, P11, and P12, which are close to agricultural areas Drose et al., 2020;Fia et al., 2009;Grützmacher et al., 2008;Valentini et al., 2021). High concentrations of nutrients discharged into surface waters under good light conditions could cause eutrophication due to increased primary productivity (Esteves, 1998;Aguiar et al., 2011;Soro et al., 2023). However, this was not observed in this study, as the O 2 concentration dissolved in the water was mostly according to regulation, and the high phosphorus levels did not correspond to an increase in chlorophyll-α, indicating low primary productivity in the lagoon. ...
... They also found higher phosphorus levels during monitoring and a low N:P ratio, as in this study. This low ratio (N:P) could limit primary productivity due to available nitrogen concentrations being below what primary producers need (Howarth et al., 2006;Howarth et al., 2021;Soro et al., 2023). Kratzer and Brezonik (1981) studied shallow tropical lakes in Florida and considered that N:P ratios less than 10 limits primary productivity by nitrogen. ...
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This study performed toxicity assays with microalgae, microcrustaceans, and fish as well as evaluated biochemical and behavioral biomarkers in fish and microcrustaceans to assess the quality of the surface water of Mirim Lagoon, which belongs to one of the largest hydrographic basins in the world, located in southern Brazil. Three distinct sampling periods were chosen (January, March, and June 2022) based on the rice plantation dynamics which is the main activity surrounding the lagoon. In January, the plantation is irrigated; in March, the water is drained into the Mirim Lagoon, and July is the off-season. Concerning toxicity tests, there was significant inhibition in microalgae growth when exposed to water collected in March, but no mortality was observed for Ceriodaphia dubia, Daphnia magna, and Danio rerio. Regarding biomarkers, behavioral variables contributed more to the higher values of the Integrated Biomarker Response (IBR) index for both D. magna and D. rerio, in March. The Redundancy Analysis (RDA) indicated a correlation between the biomarkers for both organisms and abiotic parameters, mainly nutrients (total phosphorus and total nitrogen), thermotolerant coliforms, total solids, and turbidity. Spatially, there was no difference during monitoring, but the most significant ecotoxicological effects were observed in March. Multivariate analysis and the IBR index proved to be useful tools for monitoring of water bodies such as Mirim Lagoon.
... However, excess nutrients in water bodies can favor the massive growth of aquatic plants interfering with the desirable uses of water (eutrophication - Thomann & Mueller, 1987), can cause methemoglobinemia in infants due to the high nitrate concentration (Johnson, 2019), and can intoxicate aquatic animals by the high concentrations of NH 3 (aq) Zuffo et al., 2021). Excess nutrients in water bodies have been studied in several countries, such as Russia (Sorokovkovaa et al., 2022), Uruguay (Blanco & Letelier, 2021), the Ivory Coast (Soro et al., 2023), China , the Netherlands (Rozemeijer et al., 2021), and Brazil (Anjinho et al., 2021), but mapping the different sources of contamination remains an essential and challenging issue to technically support managers for decision-making regarding important subjects, such as the one described previously (Miller et al., 2020;Yibin et al., 2021). ...
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... The septage wastewater is composed of effluent after the removal of sludge and other solid particles, it is rich in nitrogen due to the removal of the amine group from food during digestion and released in form of urine [32,36]. Nitrogen together with phosphates can promote eutrophication leading to harm to the environment [37,38]. This suggests that treating septage wastewater is highly important to prevent environmental disruption. ...
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Septage wastewater is rich in ammonia that could harm human health and the environment if released in nature untreated. Recently, we reported the efficiency and cost-effectiveness of electrocoagulation in treating septage wastewater. An antioxidant like persulfate could act as electron shuttles (ES) and could potentially improve the electrochemical reaction of electrocoagulation (EC) in treating wastewater. Thus, in this research, a black iron electrode with a persulfate additive was considered in the electrocoagulation treatment of septage wastewater and several parameters was monitored through time. EC-treated samples were NH3 and TSS-free after 60 min. Likewise, COD and oil and grease were reduced to 76.30% and 91.63% respectively. Compared to our previous study, the use of persulfate additive improved the pollutants removal and the process is more cost-effective due to a lesser electrode consumption (0.25%).
... Dentre os efeitos ao sistema desses dois compostos é que esses dois nutrientes são alguns dos fatores essenciais para qualificar o grau de trofia em corpos d'águas, esse grau está associado à tendência de aumento da biomassa na água que desestabiliza o equilíbrio dos ecossistemas aquáticos e usos múltiplos como abastecimento e recreação. Insumos como fertilizantes e sedimentos provenientes de atividades agrícola e urbana, presença da vegetação ripária junto a períodos chuvosos e secos são alguns dos fatores que podem afetar a entrada e o controle desses compostos no sistema aquático e resulta em mudanças no estado de trofia deles (Lønborg et al., 2021;Soro et al., 2023). ...
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Recent increases in the frequency of extreme floods and droughts associated with climate change can affect fluctuating groundwater or wetland water levels and wetland plant growth, and consequently cause redox condition changes in nitrogen dynamics in wetland sediments. Here, we studied the fate of nitrate (NO3-), dissolved organic carbon (DOC), and the microbial characteristics at different sediment depths in response to water levels (i.e., 5 or 2.5 cm) above the sediment surface and in the presence or absence of plants (Phragmites communis Trin) for four months in three wetland mesocosms. Results showed that mesocosm A (MA) with a high water level (5 cm above the surface) and plants had significantly higher DOC concentrations (17.57 ± 8.22 mg/L) in sediment that were actively consumed by microorganisms than other mesocosms with low water level (MB) and without plant (MC) (8.77 ± 2.38 mg/L and 7.87 ± 2.72 mg/L in MB and MC, respectively). Consequently, the most of influent NO3- (20 mg-N/L) dramatically reduced in the vicinity of plant roots (-20 to -15 cm sediment depth) where active denitrification was expected in MA. Moreover, the functional genes involved in denitrification such as narG (2.4 × 108 -3.5 × 108 copies·g-1) and nirS (5.6 × 106-1.1 × 107 copies·g-1) were more abundant in this mesocosm. The profile of the microbial community structure at the class level revealed that Alphaproteocbacteria (MA: 14.19 ± 1.19%; MB: 14.01 ± 0.51%; MC: 15.21 ± 2.76%) and Actinobacteria (MA: 8.21 ± 1.91%; MB: 13.91 ± 2.13%; MC: 11.75 ± 3.43%) were predominant in all three mesocosms. Interestingly, the clustered heatmap supported the obvious difference in microbial composition of MA from other mesocosms showing relatively more abundant Clostridia (6.71 ± 1.54%) and Deltaproteobacteria (7.05 ± 0.68%). These results can provide an insight to understand the biogeochemical nitrogen cycle associated with climate change in wetland systems.
Article
To face the difficulties involved in supplying freshwater to Abidjan (Côte d’Ivoire), the Aghien Lagoon connected by a channel to the Potou-Ébrié lagoon is a potential resource for production of drinking water. A hydro-meteorological network was installed with the objective of assessing the sustainability of the lagoon in terms of both quantity and quality, and 10 sampling campaigns were conducted between June 2015 and December 2016 to evaluate the water quality. Even if the annual flow of the two peri-urban tributaries is just equivalent to the volume of the lagoon, the large daily inflow by the channel can secure the future quantitative demand. Unfortunately, the main tributaries in the peri-urban zones have lacked sanitation services and present numerous markers of pollution. Even if the water quality status of the lagoon remains quite good with respect to total nitrogen and total phosphorus, it nevertheless presents a high potential risk of eutrophication.
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Bed sediment carbon to nitrogen (C/N) ratio is one of the essential variables reflecting sources of organic matter in river basins. In order to explore the spatial variability in sources of sediment C/N ratios, and the influence of land use and land cover (LULC) changes on the Betwa River basin in Peninsular India, 51 river bed sediment samples were collected in December 2016. The coefficient of variation (CV) was >35% indicating highly variable biogeochemical parameters. The sediment C/N ratio varied from 2.94 to 10.09, 3.21–56.40, and 6.50–76.97 in upstream, mid-stream, and downstream regions, respectively, indicating a progressive change in sources of organic matter and depositional environment. The positive correlation between total carbon (TC) and C/N ratio was increasing in the downstream direction [upstream (+0.560) < mid-stream (+0.603) < downstream (+0.838)], which is an indication of high deposition and slow decomposition of sedimentary terrigenous organic matter distant from the regions of urban pollution. The LULC change analysis done by remote sensing and Geographic Information System (GIS) methods revealed an adverse change for the forests and barren land and a positive change for the agricultural land and built-up areas. The sediment C/N ratio mapping showed the impact of LULC changes on the sediment quality. The spatial distribution of bed sediment C/N ratio in the Betwa River basin has important reference value for managing organic matter transport in the downstream Yamuna River and Ganga River basin.