Hydrochemical Characteristics and Influencing Factors of Groundwater in Huanglong, a World Natural Heritage

Abstract

Groundwater was collected from Huanglong. Analysis of hydrochemical characteristics using mathematical and statistical methods. Piper's trilinear diagram analysis of hydrochemistry types, Gibbs diagram and ion correlation analysis were used to explore the sources of major ions in groundwater and the factors affecting the Calculation of water quality mineral saturation indices using Phreeqc Interactive to predict trends in caliche deposition. The results showed that the groundwater in the study area most of them belonged to weakly alkaline water. Groundwater cations are mainly Ca 2+ , anions are mainly , and the hydro-chemical type is HCO 3-Ca. Pearson correlation analysis of major ions showed that TDS was strongly positively correlated with Ca 2+ , and , and all of these ions contributed to TDS. The water-rock model analysis shows that the hydrochemical genesis of groundwater in the study area is mainly controlled by rock weathering, and most of the ions are influenced by the water-rock action of carbonate rocks, and there is almost no ion-exchange action. The related research results can provide scientific references for water resources planning and allocation in the study area.

Full text

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ISSN 0097-8078, Water Resources, 2023, Vol. 50, No. 4, pp. 619–632. © Pleiades Publishing, Ltd., 2023.
Hydrochemical Characteristics and Influencing Factors
of Groundwater in Huanglong, a World Natural Heritage
Wenhao Gaoa, b, Jing Zhangc, Weizhen Zhangc, Dong Sunb, d, Jiawei Guob, d, Songjiang Zhaob,
Ying Zenga, *, and Xinze Liub, d, **
a College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu, 610059 China
b Sichuan Geological Environment Survey and Research Center, Chengdu, 610081 China
c College of Ecology and Environment, Chengdu University of Technology, Chengdu, 610059 China
d Sichuan Huadi Construction Engineering Co., Ltd., Chengdu, 610081 China
*e-mail: zengyster@163.com
**e-mail: cliu_7411@163.com
Received November 13, 2022; revised December 19, 2022; accepted January 29, 2023
Abstract—Groundwater was collected from Huanglong. Analysis of hydrochemical characteristics using
mathematical and statistical methods. Piper’s trilinear diagram analysis of hydrochemistry types, Gibbs dia-
gram and ion correlation analysis were used to explore the sources of major ions in groundwater and the fac-
tors affecting the Calculation of water quality mineral saturation indices using Phreeqc Interactive to predict
trends in caliche deposition. The results showed that the groundwater in the study area most of them belonged
to weakly alkaline water. Groundwater cations are mainly Ca2+, anions are mainly , and the hydro-
chemical type is HCO3-Ca. Pearson correlation analysis of major ions showed that TDS was strongly posi-
tively correlated with Ca2+, and , and all of these ions contributed to TDS. The water-rock model
analysis shows that the hydrochemical genesis of groundwater in the study area is mainly controlled by rock
weathering, and most of the ions are inf luenced by the water-rock action of carbonate rocks, and there is
almost no ion-exchange action. The related research results can provide scientific references for water
resources planning and allocation in the study area.
Keywords: karst, groundwater, hydrochemistry, travertine, Huanglong, Qinghai-Tibet Plateau
DOI: 10.1134/S0097807823040164
INTRODUCTION
Huanglong is located in the southern section of
Minshan Mountain Range in Songpan County, Aba
Tibetan and Qiang Autonomous Prefecture, northern
Sichuan Province, which is a transition zone from the
eastern edge of the Qinghai-Tibet Plateau to the Sich-
uan Basin. The highest peak in the region is Xuebao
Peak, the main peak of Minshan Mountain, with an
altitude of 5588 m. Xuebao Peak is covered with snow
all the year round and is the easternmost point of
modern glaciers in China at present [36]. Huanglong
is located in the background of typical alpine karst
accumulation geomorphology, with extensive and
thick travertine deposits. The area has unique traver-
tine pools, travertine beach currents, travertine water-
falls and other amazing high-altitude travertine land-
scapes. Due to the uniqueness and preciousness of its
rich and colorful landscape, Huanglong has been
included in the “World Cultural and Natural Heritage
List,” national geological park, nature reserve and 5A
Scenic spot [23].
Travertine refers to porous calcium carbonate
deposited on the surface due to supersaturation of cal-
cium carbonate due to CO2 loss in spring, river or lake
rich in calcium bicarbonate under appropriate physi-
cal, chemical or biological conditions [30, 31]. The
chemical reaction can be simplified as follows:
It can be seen that the formation of trabeculin first
occurs when the water is rich in calcium bicarbonate,
and then when there are physical [20] (e.g., increased
temperature and velocity), chemical [29] (e.g.,
increased pH), or biological [34] (e.g., photosynthesis
of aquatic plants) conditions for the supersaturation of
calcium carbonate due to the loss of CO2 [26]. The
formation of Huanglong traverte is due to the high
pressure CO2 in the deep earth producing groundwater
rich in calcium bicarbonate in the recharge area of car-
bonate rocks. When it is exposed to the surface in the
form of spring, the partial pressure of CO2 in spring
−
3
HCO
−
2
4
SO
−
3
HCO
+−
+ = ↓+ ↑+
2
3322
Ca 2HCO CaCO CO H O.
HYDROCHEMISTRY, HYDROBIOLOGY:
ENVIRONMENTAL ASPECTS

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WATER RESOURCES Vol. 50 No. 4 2023
WENHAO GAO et al.
water is much higher than that in air, and a large
amount of CO2 in spring water escapes, resulting in
supersaturation of calcium carbonate and deposition
[33]. In the process of flowing downstream, the water
temperature and velocity of spring water constantly
change [24, 40], in addition to the mixing effect of
algae and other plants with sediment carrying snow-
melt water in the ditch, resulting in different deposi-
tion rates of calcium carbonate [22, 38], and make the
travertine appear yellow, white, blue, green, black and
other colors.
However, in recent years, due to the drastic change
of geological environment and the degradation of the
travertine dam, the phenomenon of the collapse of the
travertine dam, the cracking of the dam body and the
spalling of the dam body are increasing [1]. The
dynamic influence of precipitation [12], the diversion
of water flow migration [9], the imbalance of hydro-
chemical dynamic balance [41], and the negative
interference of human activities will aggravate the deg-
radation of the travertine landscape [10]. The damage
of travertine landscape will directly affect the human-
istic value, scientific research value and ornamental
value of travertine landscape. At the same time, the
evolution of the travertine landscape has been
occurred, due to the sand tufa deposition, washed
down from upstream from pools are alluvial fill, color-
ful pond silt f lat after dying, bottom tufa deposition
can be converted into travertine beach, travertine
beach flow because of the high deposition rate, feed-
back on micro topography is more sensitive [8], easy to
form a shallow pit in different sedimentary place, the
embryonic form of pools, The evolution trend of
beach current and pools depend on the supply of karst
water source [21]. Therefore, it is urgent to explore the
characteristics of travertine deposition in Huanglong
Scenic area, and analyze the influence of hydrody-
namic, hydrochemical and biological regulation on
travertine deposition.
In recent years, the focus of travertine research has
been to improve our knowledge of specific sedimen-
tary processes, especially aspects of groundwater
chemistry. For example, the links between seasonal
climate, groundwater circulation, spring water con-
centration, and changes in the spatial distribution of
travertine deposits have been studied in river systems
[7]. As noted by Drysdale et al. [6] the results show
that the change of CaCO3 deposition in the upper
reaches of the study reach is directly related to the
change of daily water temperature, which controls the
rate of CO2 degassing to the atmosphere [5]. The spe-
cific objectives of the present study were (1) Deter-
mine the hydrochemical characteristics and seasonal-
variations of inorganic ion content of the water [39];
(2) Determine the main mechanism controlling the
water geochemistry characteristics [19].
MATERIALS AND METHODS
Study Area
Huanglong is located in the western Sichuan pla-
teau, the middle of the Minshan Mountains. The
annual rainfall is 758 mm and the average annual tem-
perature is 1.1°C [33]. The mountains and valleys
around the scenic area are precipitous, with Quater-
nary glacial terrain [18]. The scenic spot is 3.5 km
above sea level from 3115 m (Fuyuan Bridge) to
3578 m (Wangxiang Terrace), with an average gradient
of 13.2%. Along the way, terraced travertias are depos-
ited in long strips, like a golden dragon soaring down
(Fig. 1).
Experimental Methods
Through the analysis of various groundwater
hydrochemical indexes of Huanglong travertine, the
hydrochemical conditions needed for the deposition
of travertine can be improved. In this chapter, the
characteristics of hydrochemical changes of deposi-
tional travertine water are compared and analyzed.
The deposition of calcite is controlled by many fac-
tors, including: (1) the concentration of each compo-
nent in the water sample, (2) the partial pressure of
carbon dioxide in the water sample, (3) the proportion
of chemical components in the water sample, and
(4) the release rate of carbon dioxide. In recent years,
biological factors have also been involved in Huan-
glong travertine deposition, but the hydrochemical
condition is still the most important factor affecting
the travertine deposition. The physicochemical
parameters in this paper mainly include the concen-
tration of major ions and CO2, the partial pressure of
CO2, the proportion of major ions, the type of hydro-
chemistry and the saturation index of minerals.
Detailed analysis of the Huanglong travertine water
chemical characteristics of water body, to further
understand the alpine karst mountainous area the
controlling factors influencing the tufa deposition is of
great importance, through the spot investigation,
Huanglong scenic spot contrast Huanglong several
year data of groundwater and the local tourism
resources development and utilization of the status
quo, in July 2019 and September 13 on the Huanglong
groundwater water samples respectively.
The main test items are Ca2+, Mg2+, Na+, K+,
, , Cl−, pH,CO2 and TDS [4]. Ca, Mg, Na
and K were determined by flame atomic absorption
spectrometry; is determined by hydrochloric
acid titration, and Cl− are determined by ion
chromatograph, CO2 are determined by sodium
hydroxide titration, TDS and pH are determined by
−
2
4
SO
−
3
HCO
−
3
HCO
−
2
4
SO

WATER RESOURCES Vol. 50 No. 4 2023
HYDROCHEMICAL CHARACTERISTICS AND INFLUENCING FACTORS 621
multi parameter water quality analyzer on site. K+
detection limit is 0.05 mg L−1, Na+ detection limit is
0.01 mg L−1, Ca2+ detection limit is 0.02 mg L−1, Mg2+
detection limit is 0.002 mg L−1, Cl− detection limit is
0.007 mg L−1, and detection limit is 0.018 mg L−1.
was calculated by the above parameters.
In this paper, the hydrochemical data statistics are
carried out through Excel, combined with the hydro-
geological conditions of the study area, and the hydro-
chemical characteristics and control factors are ana-
lyzed by comprehensively using the methods of math-
ematical statistics, Pearson correlation analysis, Piper
three line diagram, Gibbs diagram and ion ratio end
element diagram. Among them, Piper three line dia-
gram and Gibbs diagram are drawn by Origin 2022,
and the correlation between ions and systematic clus-
ter analysis of hydrochemical characteristics are ana-
lyzed by Spss26.
2
CO
P
RESULTS AND DISCUSSION
This chapter makes a detailed statistical analysis on
the hydrochemical characteristics, influencing factors
and main ion sources of Huanglong groundwater.
Hydrochemical Characteristics
The Concentration of the Major Ions
The content of calcium carbonate in travertine sed-
iments accounts for a large proportion, generally more
than 90%. Kawai et al. [15] proposed that the main
factors controlling the deposition rate of travertine are
Ca2+ content and alkalinity. Through experiments, it is
found that the deposition rate of travertine is relatively
low when the Ca2+ concentration in water samples is
lower than 65 mg L−1. Therefore, in the process of
Travertine Deposition, the concentrations of Ca2+ and
Fig. 1. Location of the Huanglong and sampling points.
32q45c30cc N
32q45c0cc
32q44c30cc
32q44c0cc
32q43c30cc
103q49c30cc 103q50c0cc E
Sampling Point
Huamglong Valley
0 0.5 1
km

622
WATER RESOURCES Vol. 50 No. 4 2023
WENHAO GAO et al.
in travertine water samples are more important
factors.
13 groundwater samples were collected in July and
September 2019, respectively, and the hydrochemical
parameters are shown in Table 1.
The cationic mass concentration of groundwater in
the study area is related to Ca2+, Mg2+, Na+, K+, the
mean values in July were 84.1, 11.4, 1.8, and 0.45 mg
L−1, respectively; the mean values in September were
75.5, 11.5, 1.8, and 0.34 mg L−1, respectively. The
anion concentration relationship is , , Cl−,
the mean values in July were 357, 33.0, 1.6 mg L−1,
respectively. The mean values in September were 330,
40.4 mg L−1, respectively. The TDS of groundwater in
July was 236–321 mg L−1, with an average of 267 mg
L−1. In September, the TDS of groundwater was 240–
290 mg L−1, with an average of 261 mg L−1. In July, the
pH value ranged from 7.0 to 7.7 with an average of 7.5,
and in September, the pH value ranged from 7.4 to 8.0
with an average of 7.7, mainly belonging to weakly
alkaline water. The cations in the study area were
mainly Ca2+, and the anions were mainly . As
can be seen from Table 1, the coefficient of variation of
Cl– was the largest, which was 45.6 and 41.6%, respec-
tively. Hydrochemical K+ and ions are relatively
stable and conservative ions, which are less affected by
water-rock interaction and can better trace the influ-
ence of exogenous inputs such as upstream grazing
−
3
HCO
−
3
HCO
−
2
4
SO
−
3
HCO
−
2
4
SO
and tourist activities on groundwater hydrochemistry
[42]. In this study, the coefficient of variation of the
overall detection results of water body changed greatly,
indicating that the evolution was relatively complex.
Combined with Fig. 2, it can be seen that the main
ions in Huanglong travertine groundwater are rela-
tively stable throughout the whole area from the
upstream head to the downstream. The main cationic
Ca2+ concentration in the water was relatively high,
which was 63.8–117 mg L−1 in July and 64.3–87.0 mg
L−1 in September. was the main anion in the
water body, and the contents of in July and
September ranged from 315 to 401 and 278 to 377 mg
L−1, respectively. The change of ion concentration
along the way indicates that Huanglong travertine
water body has experienced a deep cycle and retention
time, and the interaction time of water and rock is suf-
ficient. Besides, with the deposition of travertine, the
parameter concentration value of travertine water
body does not fluctuate, and the overall value is rela-
tively stable.
pH, TDS, CO2, P2 Characteristics
CO2 is an important factor affecting Travertine
Deposition. When the travertine groundwater deposit-
ing travertine is exposed to the surface, because the
partial pressure of carbon dioxide in the travertine
water is higher than that in the atmosphere, in order to
−
3
HCO
−
3
HCO
Table 1. The mass concentration of main ions in the groundwater of Huanglong
Ion Date Maximum Minimum Average Standard
deviation
Coefficient
of variation, %
pH July 7.7 7.0 7.5 0.17 2.2
September 8.0 7.4 7.7 0.15 2.0
TDS July 321 236 267 25.2 9.4
September 290 240 261 17.3 6.6
Na+July 2.1 1.5 1.8 0.19 10.4
September 2.0 1.4 1.8 0.21 11.6
K+July 0.54 0.38 0.45 0.05 10.9
September 0.38 0.30 0.34 0.02 6.3
Mg2+ July 12.9 10 .1 11.4 0.9 0 7.9
September 12.0 10.3 11.5 0.59 5.2
Ca2+ July 117 63.8 84.1 15.9 18.9
September 87.0 64.3 75.5 8.14 10.8
Cl–July 3.5 0.9 1.6 0.71 45.6
September 1.9 0.5 1.0 0.41 41.6
July 37.0 30.4 33.0 2.19 6.6
September 46.9 36.3 40.4 2.81 6.9
July 401 315 357 34.5 9.7
September 377 278 330 29.2 8.8
−
2
4
SO
−
3
HCO

WATER RESOURCES Vol. 50 No. 4 2023
HYDROCHEMICAL CHARACTERISTICS AND INFLUENCING FACTORS 623
achieve balance with the atmosphere, CO2 will escape
from the travertine water, which is conducive to the
deposition of travertine. Through the study of the trav-
ertine water depositing travertine in Iceland, it is pro-
posed that the rapid escape of CO2 along the f low path
of travertine water is conducive to the deposition of
travertine [16, 25]. pH is a common parameter in the
hydrochemical analysis of travertine water, and is
affected by many factors, such as the temperature,
and components of travertine water. pH and
are not linear correlation, but a logarithmic correla-
tion. As an indicator of water salinity, TDS total dis-
solved solids are mainly affected by the differences of
geochemical conditions, hydrogeological conditions
and lithology [27].
See Table 2 for the test results of pH, TDS, CO2
and calculated values.
According to the values of CO2 and in Table 2,
the variation law of CO2 concentration and of 1–
13# in Huanglong travertine groundwater is drawn.
Figure 3 shows that the groundwater of Huanglong
travertine contains relatively high concentrations of
CO2 and , and the CO2 concentration and
values vary greatly, ranging from 10 to 45 mg L−1 and 4
to 75 atm, respectively. is much higher than the
atmospheric partial pressure of carbon dioxide
0.0004 hPa. The release of CO2 is not only controlled
by , but also related to the underground flow path
of travertine water, velocity and other water cycle pro-
cesses.
2
CO
P
2
CO
P
2
CO
P
2
CO
P
2
CO
P
2
CO
P
2
CO
P
2
CO
P
2
CO
P
It can be seen fr om Fig. 4 that the pH of Huanglon g
groundwater is between 7–8, and there is an obvious
logarithmic relationship between pH and (R >
0.999). pH can reflect in water to a certain extent,
so pH can also be used as an indicator of Travertine
Deposition. When the pH is greater than 8, the
value is very small. If the groundwater is exposed to the
surface at this time, the deposition of travertine will be
very difficult.
Cluster Analysis
Cluster analysis is a method of multivariate statisti-
cal classification, which is based on the similarity
of different objects. Clustering analysis is divided into
R-type clustering and Q-type clustering [14]. In this
paper, R and Q-type classification are respectively
used to analyze the water samples in the study area.
When the distance is 50, it can be seen from Fig. 5a
that the sampling points in July can be aggregated into
three categories: the first category is 1#, 3#, 4#, 5#,
6# and 7#; the second category is 2#; the third cate-
gory is 8#, 9#, 10#, 11#, 12# and 13#; Fig. 5b shows
that the sampling points in September can be aggre-
gated into two categories: the first category is 1#, 2#,
3#, 4#, 5#, 6#, 7# and 9#; the second category is 8#,
10#, 11#, 12# and 13#; At a distance of 400, it can be
seen from Fig. 5c and Fig. 5d that the overall hydro-
chemical indexes in July and September are aggre-
gated into two categories: the first category is
and TDS, and the second category is Ca2+, Mg2+,
Na+, K+, Cl−, pH and . The Q-type clustering
2
CO
P
2
CO
P
2
CO
P
−
3
HCO
−
2
4
SO
Fig. 2. Changes of groundwater chemical parameters (mg/L, except pH).
9# 10# 11 # 12# 13#8#7#6#5#4#3#2#1#
0
July
14
3.0
1.5
0
0.5
1.0
0
0
2
0
30
4
60
250
0
0
200
400
500
0
7
150
75
9
8
7
September
HCO3
–
mg/Lmg/Lmg/Lmg/L mg/Lmg/L mg/L mg/L pH
,TDS,
SO2–,
4
Cl–,K+,Na+,Mg2+,Ca2+,

624
WATER RESOURCES Vol. 50 No. 4 2023
WENHAO GAO et al.
analysis combined with the distribution of sampling
points in the study area and the corresponding ion
mass concentration shows that the aggregation classi-
fication of sampling points is based on the upstream
and downstream relationship of the study area, while
the R-type clustering analysis shows that the ion mass
concentration is relatively stable after the arrival of the
wet season.
Hydrochemical Type
The hydrochemical type of water will also affect
Travertine Deposition to a certain extent. Travertine is
easier to deposit near the water with hydrochemical
type of HCO3–Ca [3, 13]. The hydrochemical type of
water is determined by Piper diagram [32]. The con-
centration of was not considered when drawing
Piper diagram because its concentration was lower
than the lowest concentration tested.
−
2
3
CO
As can be seen from Fig. 6, Ca
2+ in cations and
in anions of 13 Huanglong groundwater sam-
ples are all more than 75 and 85%, respectively occu-
pying the absolute dominant position of cand anions.
It can be determined that all groundwater hydrochem-
ical types in Huanglong are HCO3-Ca type.
Pearson Correlation
Each ion index in groundwater does not exist
alone, but is related to a certain extent. The source of
ions is preliminarily analyzed through Pearson cor-
relation analysis.
As can be seen from Fig. 7, various index parame-
ters are correlated to different degrees, and the degree
of correlation can be further judged by the critical cor-
relation coefficient [2]. The critical correlation coeffi-
cient is shown in Table 3.
−
3
HCO
Table 2. Physical parameters of travertine water
Sample ID Date pH,
mg L−1
TDS,
mg L−1
CO2,
mg L−1
,
hPa
1# July 7.4 266 16.2 14.1
September 8.0 281 30.7 3.2
2# July 7.0 321 16.2 35.5
September 7.4 290 15.3 13.0
3# July 7.5 290 44.3 10.8
September 7.8 269 25.6 4.5
4# July 7.6 294 17.9 8.3
September 7.7 264 35.8 5.6
5# July 7.5 282 17.9 9.8
September 7.8 264 25.6 4.8
6# July 7.5 282 17.0 10.9
September 7.7 287 25.6 6.1
7# July 7.5 267 23.9 9.7
September 7.8 270 37.5 4.7
8# July 7.6 236 21.3 6.9
September 7.9 240 29.0 3.2
9# July 7.5 250 20.5 8.9
September 7.5 256 39.2 8.9
10# July 7.5 253 21.3 9.2
September 7.7 244 15.3 5.2
11# July 7.7 242 18.7 5.5
September 7.7 245 25.6 5.5
12# July 7.6 251 11.1 7.1
September 7.7 245 29.0 4.8
13# July 7.6 241 11.1 7.3
September 7.7 244 25.6 5.4
2
CO
P

WATER RESOURCES Vol. 50 No. 4 2023
HYDROCHEMICAL CHARACTERISTICS AND INFLUENCING FACTORS 625
The correlation coefficients of TDS with Ca2+,
and in July and September were all >0.8,
which showed a strong correlation with TDS, indicat-
ing that they were the main source of TDS. The cor-
relation coefficient between and Ca2+ was >0.6,
indicating that the source of was probably deep
gypsum.
Mineral Saturation Index (SI)
Mineral saturation index (SI) has important indic-
ative significance for mineral deposition and dissolu-
tion. Calcite saturation index can indicate the deposi-
tion of travertine to a certain extent. The deposition of
travertine mainly depends on the concentration of
Ca2+ and , and the calcite minerals in the solu-
tion must be supersaturated. It is proposed that calcite
mineral saturation index is an obvious parameter,
which can be used to study the hydrochemical charac-
teristics of karst water system.
Mineral SI is the logarithm of the ratio of ionic
activity product (Q) to dissolution equilibrium con-
stant (K), and the expression is:
When SI > 0, it means that the mineral is saturated
and tends to deposit. When SI < 0, it means that the
mineral is unsaturated. When SI = 0, it means that the
mineral is in equilibrium. Based on available hydro-
chemical data the saturation index of anhydrite, ara-
gonite, calcite, dolomite, gypsum and halite in water
samples is calculated and determined by Phreeqc
Interactive [28].
As shown in Fig. 8, the saturation index of arago-
nite, calcite and dolomite in most of the groundwater
samples in the whole Huanglong region is greater than
0, and the saturation index of aragonite, calcite and
dolomite in the water samples is decreasing compared
with other water samples, and the saturation index of
−
2
4
SO
−
3
HCO
−
2
4
SO
−
2
4
SO
−
3
HCO
(
)
=
SI log .
QK
calcite drops to negative without reaching the satura-
tion state. This indicates that once the 2# water sample
is exposed to the surface, the deposition of travertine
may not occur.
Influencing Processes
Studying the influence mechanism of groundwater
has a very important impact on mastering the hydro-
chemical genesis of groundwater. The influencing
processes of groundwater Hydrochemistry in the study
area can be roughly divided into three types: rock
weathering, leaching and ion exchange.
Rock Weathering
In the process of perennial flow, groundwa-
ter reacts with the minerals in the riverbed, and also
−
3
HCO
Fig. 3. Variation diagram of CO2 concentration and ((a) July; (b) September).
3# 5# 8# 10# 12#13#11#9#7#6#4#2#1#
0
CO2, mg/L
25
50 75
50
25
0
PCO2, hPa
P
CO2
CO
2
3# 5# 8# 10# 12#13#11#9#7#6#4#2#1#
0
CO2, mg/L
25
50 75
50
25
0
PCO2, hPa
P
CO2
CO
2
(a) (b)
2
CO
P
Fig. 4. Relationship between pH and .
30 35 402520151050
pH
7.2
7.4
7.6
7.8
8.0
8.2
7.0
8.4
P
CO2
July
September
y = –0.468* ln (x + 1.449) + 8.610
R = 0.9995
y = –0.409* ln (x + 2.200) + 8.518
R = 0.9999
2
CO
P

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WATER RESOURCES Vol. 50 No. 4 2023
WENHAO GAO et al.
has the influence of rainfall and evaporation. Gibbs
diagram intuitively shows the chemical composition
characteristics, control factors and mutual relation-
ship of groundwater through semi logarithmic coordi-
nate diagram [11]. The groundwater samples of Huan-
glong travertine were analyzed by Gibbs diagram
(Fig. 9).
The TDS of groundwater samples in the study area
is lower than 1000 mg L−1, ρ (Na+)/ρ(Na+ + Ca2+)
ratio ranges from 0.01 to 0.02, ρ(Cl−)/ρ(Cl− + )
ratios are less than 0.02, along the direction of ground-
water flow. The ratio of ρ(Na+)/ρ(Na+ + Ca2+)
decreases gradually, and all groundwater samples are
in the rock weathering control area, which shows that
the formation mechanism of groundwater in the study
area is mainly rock weathering, and the contribution
of evaporation crystallization and atmospheric precip-
itation is very small.
Dissolution and Filtration
The formation of groundwater can be reflected by
analyzing the proportional relationship between Mg2+
and Ca2+ and Na+, etc. [17]. Huanglong groundwater
ρ(Mg2+)/ρ(Na+) ratios are greater than 1. The ratio of
ρ(Mg2+)/ρ(Ca2+) is less than 1 (Fig. 10), which shows
that the groundwater solution filtration in Huanglong
basin is mainly water rock interaction (CaCO3-H2O).
−
3
HCO
Fig. 5. Q-type of hydrochemical index ((a) July; (b) September); R-type cluster analysis diagram of sampling points ((c) July;
(d) September).
120010008006004002000
HCO3
–
TDS
pH
SO2–
4
Cl–
K+
K+
Na+
Mg2+
Ca2+
120010008006004002000
HCO3
–
TDS
pH
SO2–
4
SO2–
4
Cl–
Na+
Mg2+
(a) (b)
(c) (d)
806040200
6
5
2
11
10
12
13
4
7
8
9
3
1
60403010 20 500
2
4
5
13
11
12
3
9
7
8
10
6
1
Fig. 6. Piper thrilinear chart in Huanglong water samples.
100
July
September
80
60
40
20
0
100 80 60 40 20 0
00.2 0.4 0.6 0.8 1.0
0
0.2
0.4
0.6
0.8
1.0
00.2 0.4 0.6 0.8 1.0
0
0.2
0.4
0.6
0.8
1.0
0 0.2 0.4 0.6 0.8 1.0
00.20.40.60.81.0
Cl + SO
4
Ca + Mg
CO
3
+ HCO
3
SO4
Ca
Mg
Cl
Na + K

WATER RESOURCES Vol. 50 No. 4 2023
HYDROCHEMICAL CHARACTERISTICS AND INFLUENCING FACTORS 627
Ion Exchange
The groundwater in Huanglong area is in a com-
plex karst system, mainly calcite interacts with water,
generally, cation exchange will change some main ions
in groundwater, which is also an important role in the
hydrochemical formation of groundwater [30]. ρ(K+ +
Na+ + Cl−)/ρ(Ca2+ + Mg2+) can determine whether
cation exchange occurs in groundwater. If strong ion
exchange occurs, the slope after fitting should be −1.
According to Fig. 11, the slope between groundwater
samples is −17.15 and −25.22, respectively, indicating
that there is almost no ion exchange in Huanglong
groundwater.
Schoeller [35] proposed chlor alkali “index” CAI1
and CAI2 to represent the cation exchange and
strength. When Na+ and K+ in the water exchange
Ca2+ and Mg2+ in the adsorbed state in the riverbed
minerals, the values of CAI1 and CAI2 are positive; on
the contrary, when Ca2+ and Mg2+ in the river
exchange the adsorbed Na+ and K+ in the riverbed
minerals, the values of cai1 and CAI2 are negative; The
stronger the cation exchange, the greater the absolute
values of cai1 and CAI2. As can be seen from Fig. 12,
except that cai1 and CAI2 of sample 13# are positive
values, cai1 and CAI2 are mainly negative values. H2 is
the gully water at the upstream of erdaoping in the
Fig. 7. Correlation coefficient diagram of the groundwater hydrochemical indicators ((a) July; (b) September).
*pd–0.05 **pd–0.01 *pd0.05 **pd0.01
TDS
pH
Ca
Mg
Na
K
Cl
HCO
3
SO
4
TDS
pH
Ca
Mg
Na
Ca
Mg
Na
K
Cl
HCO
3
SO
4
TDS
pH
K
Cl
HCO
3
SO
4
TDS
pH
Ca
Mg
Na
K
Cl
HCO
3
SO
4
TDS
pH
Ca
Mg
Na
K
Cl
HCO
3
SO
4
TDS
pH
Ca
Mg
Na
K
Cl
HCO
3
SO
4
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
(a) (b)
Table 3. Critical values of Pearson correlation coefficient
Pearson correlation
coefficient Correlation
0.8‒1.0 Extremely strong correlation
0.6‒0.8 Strong correlation
0.4‒0.6 Moderate correlation
0.2‒0.4 Weak correlation
0.0‒0.2 No correlation
<0.0 Negative correlation
Fig. 8. Saturation index of minerals of groundwater ((a) July; (b) September).
(a)
Anhydrite
Aragonite
Calcite
Dolomite
Gypsum
Halite
2
0
–2
–4
–6
–8
–10
1
SI
2345678910111213
Anhydrite
Aragonite
Calcite
Dolomite
Gypsum
Halite
2
0
–2
–4
–6
–8
–10
1
SI
2345678910111213
(b)

628
WATER RESOURCES Vol. 50 No. 4 2023
WENHAO GAO et al.
study area, where positive cation action occurs. Na+
and K+ in the water exchange Ca2+ and Mg2+ in the
adsorbed state of riverbed minerals, and anti cation
action occurs in the samples in the core area. Ca2+ and
Mg2+ in the water exchange Na+ and K+ in the
adsorbed state of riverbed minerals, it further indicates
that there is no ion exchange in the study area.
Main Ion Sources
From the above discussion, it can be seen that the
groundwater in Huanglong basin is mainly controlled
by rock weathering, and mainly water rock interaction.
This paper uses Gaillardet model to judge the type of
rock weathering source controlling the Hydrochemi-
cal Composition of water.
From the relationship between ρ(Ca2+)/ρ(Na+)
and ρ(HCO3)/(Na+), ρ(Mg2+)/(Na+) concentrations
of evaporite, silicate and carbonate in the study area, it
can be seen that groudwater samples are mainly con-
centrated in carbonate rocks and evaporite salt rocks,
indicating that groundwater is affected by weathering
and dissolution of carbonate rocks (Fig. 13a) and
Fig. 9. Gibbs map of groundwater in the study area.
1.00.80.60.40.2
100
0
TDS, mg L–1
101
102
103
104
105
July
September
Water-rock
interaction
Evaporation
concentration
Atmospheric
precipitation
U(Na+/U(Na+ + Ca2+)) 1.00.80.60.40.2
100
0
TDS, mg L–1
101
102
103
104
105
July
September
Water-rock
interaction
Evaporation
concentration
Atmospheric
precipitation
3
U(Cl–/U(Cl– + HCO–))
(a) (b)
Fig. 10. Distribution of groundwater ion reaction.
1001010.1
0.01
0.01
Water-rock interaction
10
1
0.1
July September
Evaporation
Calcium salt leaching
Sodium salt leaching
U(Mg2+)/U(Ca2+)
U(Mg2+)/U(Na2+)

WATER RESOURCES Vol. 50 No. 4 2023
HYDROCHEMICAL CHARACTERISTICS AND INFLUENCING FACTORS 629
evaporation and leaching of carbonate rocks
(Fig. 13b).
The Na+ and Cl− ions in water mainly come from
the dissolution of meteoric water, silicate minerals and
evaporite minerals, and the Na+/Cl− value in meteoric
water is about 0.86 [37]. The study area is located
inland and far from the ocean, and the Na+/Cl−
ratio will be affected by atmospheric precipitation.
Figure 14a shows that ρ(Na+)/ρ(Cl−) of groundwater
samples in the study area is mainly less than 1, which
is consistent with the ratio of ρ(Na+)/ρ(Cl−) in atmo-
spheric precipitation, indicating that atmospheric pre-
cipitation is an important source of Na+ ions in
groundwater in the study area, and Cl− is insufficient
to balance Na+. However, the individual Na+ mainly
comes from the weathering dissolution of sodium car-
bonate. The ratio of ρ(Ca2+)/ρ(Mg2+) in water is
mostly above 2, indicating that the cation source of
groundwater may be silicate rock, in the disso-
lution of carbonate, and the ratio of ρ(Ca2+ +
Mg2+)/ρ( ) in most samples in the study area is
about 1. These results indicate that Ca2+, Mg2+ and
are derived from weathering of carbonate, and
there is no cation exchange. When the ratio ρ(Ca2+ +
Mg2+)/ρ( + ) is equal to 1, it indicates that
, , Ca2+ and Mg2+ in water are all derived
from weathering and dissolution of minerals. Consid-
ering the large area of travertine deposited in Huan-
glong area, calcite is the main source of these ions.
CONCLUSIONS
(1) The pH value of groundwater in the study area
is 7.0–8.0, and most of it is alkaline water. The cations
in the water are mainly Ca2+, and the anions are
mainly , and the hydrochemical type is –
Ca2+. TDS content gradually stabilized with water
flow from upstream to downstream. The relationship
between the upstream and downstream of the study
area is the aggregation classification of the sampling
points, and the R-type clustering analysis shows that
the mass concentration of each ion is relatively stable
after the arrival of the wet season.
(2) Mineral saturation index (SI) has important
indicative significance for mineral deposition and dis-
solution. According to Phreeqc Interactive 3.1.4 calcu-
−
3
HCO
−
3
HCO
−
3
HCO
−
3
HCO
−
2
4
SO
−
3
HCO
−
2
4
SO
−
3
HCO
−
3
HCO
Fig. 11. The relationship between groundwater ρ(K+ + Na+ + Cl−) and ρ(Ca2+ + Mg2+––).
8106420
–100
–2
Linear fit July
–200
–250
–300
–350
–150
–400 July
September
y = –17.15x + 293.25
R = 0.7043
y = –25.22x + 310.98
R = 0.9023
Linear fit September
–
U(Ca2+ + Mg2+ – HCO3 – SO2–), mg L–1
4
U(K+ + Na+ – Cl–), mg L–1
−
3
HCO
−
2
4
SO
Fig. 12. The relationship between CAI1 and CAI2 of
groundwater.
5.02.50–2.5
–0.02
–5.0
CAI2
0
0.02 July September
CAI1
10#

630
WATER RESOURCES Vol. 50 No. 4 2023
WENHAO GAO et al.
Fig. 13. The relationship between the concentration ratio of Ca2+/Na+ and /Na+, Mg2+/Na+ in groundwater.
Carbonatite rock
July
September
U(Ca2+)/U(Na2+)U(Ca2+)/U(Na2+)
U(Mg2+)/U(Na2+)
–
U(HCO3 /U(Na2+)
Silicate rock
Evaporated salt rock
100
10
1
0.1 1 10 100
Carbonatite rock
July
September
Silicate rock
Evaporated salt rock
100
10
1
0.1 1 10 100
(a) (b)
−
3
HCO
Fig. 14. Correlation between groundwater ions in the Huanglong.
151050
U(Cl–)
5
10
15
U(Ca2+)/U(Mg2+)
U(Ca2+)/U(Mg2+)
July September
0.20.10
0.1
0.2
July September
1050
5
10
July September
151050
5
10
15
July September
U(Na+)
U(Ca+)
U(HCO3)
–
U(HCO3 + SO4)
2
U(Mg2+)
2:1
2:1 2:1
2:1
1:1 1:1
1:1
1:1
(a) (b)
(c) (d)

WATER RESOURCES Vol. 50 No. 4 2023
HYDROCHEMICAL CHARACTERISTICS AND INFLUENCING FACTORS 631
lation, when the groundwater with SI saturation
reaches the surface, the deposition of traverts may
occur.
(3) There is a strong positive correlation between
TDS and Ca2+, and , and the correlation
coefficients are above 0.8, which are the main sources
of TDS. The strong correlation between and
Ca2+ indicates that may come from gypsum in
deep underground.
(4) According to the Gibbs diagram analysis, the
hydrochemical composition of different water bodies
is mainly controlled by water-rock interaction, and the
Gaillardet model is quoted to further conclude that
most ions are dissolved by weathering of carbonate
rocks, and there is no ion exchange in cation sources.
ACKNOWLEDGMENTS
The test data of this paper comes from Sichuan Univer-
sity of Science & Engineering and Keyuan Engineering
Technology Testing Center of Sichuan Province, so I would
like to express my heartfelt thanks to these two units.
FUNDING
This work was financially supported by Huanglong National
Scenic Spot Administration (nos. 513220202100254,
513220202100331 and N5132112023000028), Aba Prefecture
Science and Technology Bureau (R21YYJSYJ0010), and
Sichuan Institute of Geological Survey (nos. SDDY-
Z2022008, SCIGSCYBXM-2023004).
CONFLICTS OF INTEREST
The authors declare that they have no conflicts of inter-
est.
REFERENCES
1. Akin, M. and Özsan, A., Evaluation of the long-term
durability of yellow travertine using accelerated weath-
ering tests, Bull. Eng. Geol. Environ., 2001, vol. 70,
no. 1, pp. 101‒114.
2. Arenas, C., Auqué, L., Osácar, C., Sancho, C., Loza-
no, M.V., Vázquez-Urbez, M., and Pardo, G., Current
tufa sedimentation in a high discharge river: A compar-
ison with other synchronous tufa records in the Iberian
Range (Spain), Sediment. Geol., 2015, vol. 325,
pp. 132‒157.
3. Böttcher, F. and Zosseder, K., Thermal influences on
groundwater in urban environments–A multivariate
statistical analysis of the subsurface heat island effect in
Munich, Sci. Total Environ., 2022, vol. 810.
4. Chen, J., Zhang, D.D., Wang, S., Xiao, T., and
Huang, R., Factors controlling tufa deposition in natu-
ral waters at waterfall sites, Sediment. Geol., 2004,
vol. 166, nos. 3‒4, pp. 353‒366.
5. Dai Q, W., Dang, Z., and Peng, Q.X., Porosity of trav-
ertine natural sponge geological bodies and its signifi-
−
2
4
SO
−
3
HCO
−
2
4
SO
−
2
4
SO
cance in regulating water circulation: a case study of
travertine at Huanglong ravine, Sichuan Province, Chi-
na, Acta Mineral. Sin., 2019, vol. 39, no. 2,
pp. 219‒225.
6. Drysdale, R., Lucas, S., and Carthew, K., The inf lu-
ence of diurnal temperatures on the hydrochemistry of
a tufa-depositing stream, Hydrol. Processes, 2003,
vol. 17, no. 17, pp. 3421‒3441.
7. Drysdale, R.N., Taylor, M.P., and Ihlenfeld, C., Fac-
tors controlling the chemical evolution of travertine-
depositing rivers of the Barkly karst, northern Austra-
lia, Hydrol. Processes, 2002, vol. 16, no. 15,
pp. 2941‒2962.
8. Drysdale, R.N., The sedimentological significance of
hydropsychid caddis-fly larvae (order; Trichoptera) in
a travertine-depositing stream; Louie Creek, North-
west Queensland, Australia, J. Sediment. Res., 1999,
vol. 1, pp. 145‒150.
9. Erthal, M.M., Capezzuoli, E., Mancini, A., Claes, H.,
Soete, J., and Swennen, R., Shrub morpho-types as in-
dicator for the water flow energy-Tivoli travertine case
(Central Italy), Sediment. Geol., 2017, vol. 347,
pp. 79‒99.
10. Ford, T.D., A review of tufa and travertine deposits of
the world, Earth-Sci. Rev., 1996, vol. 41, nos. 3–4,
pp. 117‒175.
11. Gibbs, R.J., Mechanisms controlling world water
chemistry, Science, 1970, vol. 170, no. 3962, pp. 1088–
1090.
12. Hosseini, M. and Fakhri, D., Effects of acid rain on
physical and mechanical properties of travertine, J.
Miner. Resour. Eng., 2021, vol. 6, no. 3, pp. 83‒97.
13. Jiang, L., Yao, Z., Liu, Z., Wang, R., and Wu, S., Hy-
drochemistry and its controlling factors of rivers in the
source region of the Yangtze River on the Tibetan Pla-
teau, J. Geochem. Explor., 2015, vol. 155, pp. 76‒83.
14. Jones, B., Renaut, R.W., Bernhart Owen, R., and Tor-
fason, H., Growth patterns and implications of com-
plex dendrites in calcite travertines from Lýsuhóll,
Snæfellsnes, Iceland, Sedimentology, 2005, vol. 52,
no. 6, pp. 1277‒1301.
15. Kawai, T., Kano, A., and Hori, M., Geochemical and
hydrological controls on biannual lamination of tufa
deposits, Sediment. Geol., 2009, vol. 213, nos. 1‒2,
pp. 41‒50.
16. Kefeni, K.K., Msagati, T.A.M., and Mamba, B.B.,
Acid mine drainage: prevention, treatment options, and
resource recovery: a review, J. Cleaner Prod., 2017,
vol. 151(MAY10), pp. 475‒493.
17. Kpegli, K., Alassane, A., Trabelsi, R., Zouari, K., and
Toro-Espitia, L.E., Geochemical processes in Kandi
basin, Benin, West Africa: a combined hydrochemistry
and stable isotopes approach, Quaternary Int., 2015,
vol. 369, pp. 99‒109.
18. Li, P., Tian, R., and Liu, R., Solute geochemistry and
multivariate analysis of water quality in the Guohua
phosphorite mine, Guizhou Province, China, Exposure
Health, 2019, vol. 11, no. 2, pp. 81‒94.
19. Li, S., Su, H., and Li, Z., Hydrochemical characteris-
tics and groundwater quality in the thick loess deposits
of China, Environ. Sci. Pollut. Res., 2022, vol. 29, no. 6,
pp. 8831‒8850.

632
WATER RESOURCES Vol. 50 No. 4 2023
WENHAO GAO et al.
20. Lin, Y.P. and Singer, P.C., Inhibition of calcite precip-
itation by orthophosphate: speciation and thermody-
namic considerations, Geochim. Cosmochim. Acta,
2006, vol. 70, no. 10, pp. 2530‒2539.
21. Liu, Y., Zhou, X., Deng, Z., Fang, B., Tsutomu, Y.,
Zhao, J., and Wang, X., Hydrochemical characteristics
and genesis analysis of the Jifei hot spring in Yunnan,
southwestern China, Geothermics, 2015, vol. 53,
pp. 38‒45.
22. Liu, Z., Li, H., You, C., Wan, N., and Sun, H., Thick-
ness and stable isotopic characteristics of modern sea-
sonal climate-controlled sub-annual travertine laminas
in a travertine-depositing stream at Baishuitai, SW Chi-
na: implications for paleoclimate reconstruction, Envi-
ron. Geol., 206, vol. 51, no. 2, pp. 257‒265.
23. Liu, Z., Svensson, U., Dreybrodt, W., Yuan, D., and
Buhmann, D., Hydrodynamic control of inorganic cal-
cite precipitation in Huanglong ravine, China: field
measurements and theoretical prediction of deposition
rates, Geochem. Cosmochem. Acta, 2011, vol. 59, no. 15,
pp. 3087‒3097.
24. Liu, Z.H., Yuan, D.X., and He, S.Y., The features of
the stable carbon isotopes and geochemistry in the sys-
tem of Carbonate-H2O-CO2 and their implications–
Evidence from several typical karst areas of China, Acta
Geol. Sin., 1997, vol. 71, no. 3, pp. 281‒288.
25. Lorah, M.M. and Herman, J.S., The chemical evolu-
tion of a travertine-depositing stream: Geochemical
processes and mass transfer reactions, Water Resou r.
Res., 1988, vol. 24, no. 9, pp. 1541‒1552.
26. Luo, L., Wen, H., Brogi, A., and Capezzuoli, E., Fac-
tors controlling the geometry of travertine mounds: In-
sights from Heinitang (China), Sedimentol., 2022,
vol. 69, no. 4, pp. 1519‒1546.
27. Otyukova, N.G., Hydrochemical Regime in Riverine
Aqual Complexes: Case Study of the Small Il’d River
(Rybinsk Reservoir Basin), Wate r Resou r., 2019, vol. 46,
no. 4, pp. 602‒604.
28. Parkhurst, D.L., User’s guide to PHREEQC
(Version 2): A computer program for speciation, batch-
reaction, one-dimensional transport, and inverse geo-
chemical calculations, Water-Resour. Invest. Rep., 1999,
vol. 99, no. 4259, p. 312.
29. Parvizpour, S., Jamshidi, A., Sarikhani, R., and Ghas-
semi Dehnavi, A., 2The pH effect of sulfuric acid on
the physico-mechanical properties of Atashkuh traver-
tine, Central Iran, Environ. Earth Sci., 022, vol. 81,
no. 5, pp. 1‒10.
30. Pentecost, A., The quaternary travertine deposits of
Europe and Asia minor, Quatern. Sci. Rev., 1995,
vol. 14, no. 10, pp. 1005‒1028.
31. Pentecost, A., Travertines, Springer, The Netherlands,
2005.
32. Piper, A.M., A Graphical interpretation of water anal-
ysis, Eos Trans. Am. Geophys. Union, 1944, vol. 25,
pp. 914‒928.
33. Qiu, S., Wang, F., Dong, F., Tian, F., Zhao, X.,
Dai, Q., and Wang, Y., Sedimentary evolution of the
Dawan travertines and their geological environmental
significance, Huanglong, China, The Deposit. Record,
022, vol. 8, no. 1, pp. 251‒265.
34. Ranjbaran, M. and Zamanzadeh, S.M., Determining
the role of chemical and biological factors in con-
trolling precipitation of tufa and travertine deposits in
Shurab area, Northern Iran, Carbonates Evaporites,
2021, vol. 36, no. 4, pp. 1‒18.
35. Scholler, H., Qualitative evaluation of groundwater re-
sources. Methods and techniques of groundwater inves-
tigations and development, Water Resour. Ser., UNES-
CO, 1965, pp. 54‒83.
36. Sun, S., Dong, F., Ehrlich, H., Zhao, X., Liu, M.,
Dai, Q., Li, Q., An, D., and Dong, H., Metabolic in-
fluence of psychrophilic diatoms on travertines at the
Huanglong natural scenic district of China, Int. J. En-
viron. Res. Public Health, 2014, vol. 11, no. 12,
pp. 13084‒13096.
37. Tiwari, A.K. and Singh, A.K., Hydrogeochemical in-
vestigation and groundwater quality assessment of Prat-
apgarh district, Uttar Pradesh, J. Geol. Soc. India, 2014,
vol. 83, no. 3, pp. 329‒343.
38. Wang, H.J., Liu, Z.H., and Zheng, C., Hydrochemical
variations of Huanglong spring and the stream in
Huanglong ravine, Sichuan province, Geochimica,
2009, vol. 38, no. 3, pp. 307‒314.
39. Wang, X., Bing, H., Wu, Y., Zhou, J., Zhu, H., Wu, Y.,
and Sun, H., Water quality variation and its condition-
ing factors in the Three Gorges Reservoir, China, J.
Water Clim. Change, 2021, vol. 12, no. 5,
pp. 1694‒1707.
40. Yoshimura, K., Liu, Z., Cao, J., Yuan, D., Inokura, Y.,
and Noto, M., Deep source CO2 in natural waters and
its role in extensive tufa deposition in the Huanglong
Ravines, Sichuan, China, Chem. Geol., 2004, vol. 205,
nos. 1‒2, pp. 141‒153.
41. Zhang, J., Wang, H., Liu, Z., An, D., and
Dreybrodt, W., Spatial–temporal variations of traver-
tine deposition rates and their controlling factors in
Huanglong Ravine, China–A world’s heritage site,
Appl. Geochem., 2012, vol. 27, no. 1, pp. 211‒222.
42. Zhang, W., Gu, P., Zheng, X., Wang, N., and
Zheng, Z., Ecological damage of submerged macro-
phytes by fresh cyanobacteria (fc) and cyanobacterial
decomposition solution (cds), J. Hazard. Mater., 2020,
vol. 401.