An investigation on groundwater geochemistry changes after 17 years: a case study from the west of Iran

Abstract

The application of chemical and organic fertilizers to agricultural lands increases nutrient pools and affects soil and water quality. Understanding changes in groundwater quality due to the anthropogenic activities over time is important to human and ecosystem health. In 2017, we resampled 58 wells monitored in the year 2000 to evaluate the rate of changes in groundwater quality and water quality indices over time in response to agricultural and industrial activities and climate changes. The groundwater in two sampling years was dominated by Ca–HCO3 water type. The mean groundwater pH, electrical conductivity (EC), calcium (\({\text{Ca}}^{2 + }\)), magnesium (\({\text{Mg}}^{2 + }\)), and sodium (\({\text{Na}}^{ + }\)) concentrations did not significantly change over time, while a significant buildup in bicarbonate \(({\text{HCO}}_{3}^{ - } )\) (189–305 mg l−1), nitrate (\({\text{NO}}_{3}^{ - }\)) (41–56 mg l−1), chloride (\({\text{Cl}}^{ - }\)) (57–77 mg l−1) and a significant decrease in sulfate (\({\text{SO}}_{4}^{2 - }\)) (159–91 mg l−1) and potassium (\({\text{K}}^{ + }\)) (3–2 mg l−1) was observed. In 2000, 45% of the water samples were classified as high salinity hazard, and this value increased to 52% by 2017, indicating that salinity of the water samples increased over 17 years. In 2000, only 25% of the total area had a \({\text{NO}}_{3}^{ - }\) value greater than 50 mg l−1; and this value increased sharply to 62% by 2017, indicating that \({\text{NO}}_{3}^{ - }\) concentrations significantly increased with approximately 2.2% annually in groundwater, over 17 years. Approximately, 55% of the groundwaters with \({\text{NO}}_{3}^{ - }\) concentration values of less than 40 mg l−1 in 2000 shifts one to four categories upward in 2017. The percentage of water samples which was shifted to the next category with \({\text{NO}}_{3}^{ - }\) concentration higher than 50 mg l−1 and approaching the limit of the World Health Organization was doubled in 2017 compared with 2000. High application of chemical and manure fertilizers in excess of crop needs should be avoided in the studied area to prevent continued increases in groundwater \({\text{NO}}_{3}^{ - }\) concentrations.

Full text

Vol.:(0123456789)
1 3
Environmental Earth Sciences (2020) 79:374
https://doi.org/10.1007/s12665-020-09114-z
ORIGINAL ARTICLE
An investigation ongroundwater geochemistry changes
after17years: acase study fromthewest ofIran
MahdiJalali1 · MohsenJalali1
Received: 2 January 2020 / Accepted: 16 July 2020 / Published online: 26 July 2020
© Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract
The application of chemical and organic fertilizers to agricultural lands increases nutrient pools and affects soil and water
quality. Understanding changes in groundwater quality due to the anthropogenic activities over time is important to human
and ecosystem health. In 2017, we resampled 58 wells monitored in the year 2000 to evaluate the rate of changes in ground-
water quality and water quality indices over time in response to agricultural and industrial activities and climate changes. The
groundwater in two sampling years was dominated by Ca–HCO3 water type. The mean groundwater pH, electrical conductiv-
ity (EC), calcium (
Ca2+
), magnesium (
Mg2+
), and sodium (
Na+
) concentrations did not significantly change over time, while
a significant buildup in bicarbonate
(HCO−
3)
(189–305mgl−1), nitrate (
NO−
3
) (41–56mgl−1), chloride (
Cl−
) (57–77mgl−1)
and a significant decrease in sulfate (
SO2−
4
) (159–91mgl−1) and potassium (
K+
) (3–2mgl−1) was observed. In 2000, 45% of
the water samples were classified as high salinity hazard, and this value increased to 52% by 2017, indicating that salinity of
the water samples increased over 17years. In 2000, only 25% of the total area had a
NO−
3
value greater than 50mgl−1; and
this value increased sharply to 62% by 2017, indicating that
NO−
3
concentrations significantly increased with approximately
2.2% annually in groundwater, over 17years. Approximately, 55% of the groundwaters with
NO−
3
concentration values of
less than 40mgl−1 in 2000 shifts one to four categories upward in 2017. The percentage of water samples which was shifted
to the next category with
NO−
3
concentration higher than 50mgl−1 and approaching the limit of the World Health Organiza-
tion was doubled in 2017 compared with 2000. High application of chemical and manure fertilizers in excess of crop needs
should be avoided in the studied area to prevent continued increases in groundwater
NO−
3
concentrations.
Keywords Water quality· Different sampling years· Nitrate pollution· Arid environment
Introduction
Groundwater in arid environments is an essential source
of drinking water and plays an important role in sustain-
ing human activities and upgrading the development of the
society and economy (Lezzaik etal. 2018). About half of the
world’s drinking water was taken from aquifers, and agri-
culture is one of the most users of groundwater (Giordano
2009), which results in lowering the water table. With the
increasing overuse of groundwater resources, the negative
effects on groundwater is also increasing (Li etal. 2018).
Anthropogenic activities have adversely affected many
aquifers; in the early part of the twentieth century, ground-
water pumping increased rapidly (Tweed etal. 2018).
Globally, about 0.75% of all water was fresh groundwater
and 0.93% was saline (Maidment 1993). Point and nonpoint
sources of groundwater contamination are very different; for
the case of point sources we can mention wastewater, septic
system leaching, and leaking barrels of waste chemicals,
and for nonpoint sources, pesticides application on fields,
polluted precipitation, and runoff from roadways (Fitts
2002). Nitrate (
NO−
3
) is one of the important components
of groundwater, and most countries consider it as a major
problem (Rodriguez-Galiano etal. 2018). The oxidation
states of nitrogen are +5, +3, 0, and −3, and in the envi-
ronment occurs in free nitrogen (
N2
), nitric oxide (
NOX
),
nitrous oxide (
N2O
), ammonia (
NH3
),
NO−
3
, nitrite (
NO−
2
),
and ammonium (
NH+
4
) (Van der Perk 2013). Typical concen-
tration ranges of
NO−
3
and
NH+
4
in groundwater are trace to
35 and trace to 9mgl−1, respectively (Van der Perk 2013).
* Mahdi Jalali
m.jalali@agr.basu.ac.ir
1 Department ofSoil Science, College ofAgriculture, Bu-Ali
Sina University, Hamedan, Iran
Content courtesy of Springer Nature, terms of use apply. Rights reserved.