Rainfall driven nitrate transport in agricultural karst surface river system: Insight from high resolution hydrochemistry and nitrate isotopes

Wang, Zhongjun; Li, Siliang; Yue, Fu‐Jun; Qin, Cai-Qing; Buckerfield, Sarah; Zeng, Jie

doi:10.1016/j.agee.2019.106787

Cited by 81 publications

(34 citation statements)

References 44 publications

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“…However, frequent rainfall did not change ion concentration largely in the following days due to adaption of water-rock reaction in high rainfall periods. Whereas SO 4 2− , K + , Na + , and NO 3 − increased quickly under heavy rain, similar to the findings of other study [27] that this group of ions were from anthropogenic discharge, washed and infiltrated into river water and elevated significantly during rainfall events. Although SO 4 2− at DJ originated similarly from mineral dissolution, which was not as susceptible to being affected by heavy rain as HCO 3 − , it is probably due to occasional manure and fertilizer decomposition, or else a contribution from acid rain.…”

Section: Response Of Groundwater To Rainfall Events and Evolution Of supporting

confidence: 90%

Temporal Variations of Water Chemistry in the Wet Season in a Typical Urban Karst Groundwater System in Southwest China

Xiao

Han

Wang

2020

IJERPH

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It is important to investigate temporal variations of water chemistry for the purpose of improving water quality in karst groundwater systems. Groundwater samples were collected daily under various land uses of Guiyang. Major ions and stable carbon isotope composition of dissolved inorganic carbon (δ13CDIC) were analyzed to understand the biogeochemical processes. The water chemistry was dominated by Ca2+, Mg2+, HCO3-, and SO42-, which mainly derived from the dissolution of carbonate rocks (limestone and dolomite) and oxidation of sulfide. The groundwater was defined as of the HCO3-Ca Mg and HCO3·SO4-Ca·Mg type, according to its hydrochemical characteristics. Results suggested that hydrochemical concentrations changed quickly, in response to rainfall events. The fast response revealed that karst groundwater was easily impacted by rainfall and anthropogenic inputs according to temporal variation of water chemistry. The distribution of DIC (dissolved inorganic carbon) and δ13CDIC showed that DIC is mainly sourced from soil CO2(g) influx and carbonate dissolution. δ13CDIC and major ions ratios suggested that carbonate minerals were dissolved by H2SO4 at groundwater in wooded area, contributing an important source for DIC due to the slight enrichment of heavy δ13CDIC. More negative δ13CDIC values were observed after rainfall reflected the fact that soil CO2(g) and organic carbon oxidation influxes accounted for a large share during DIC formation. Various δ13CDIC and hydrochemical patterns were observed under various land use and human activity conditions. Meanwhile, relative high nitrate loads were found in groundwater after rainfall, suggesting high anthropogenic inputs following rainwater as having side effects on water quality. This study suggests that water chemistry and isotopic proof provide a better understanding of water quality and carbon dynamics responding to rainfall events in the karst groundwater systems.

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Section: Response Of Groundwater To Rainfall Events and Evolution Of supporting

confidence: 90%

Temporal Variations of Water Chemistry in the Wet Season in a Typical Urban Karst Groundwater System in Southwest China

Xiao

Han

Wang

2020

IJERPH

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“…In the karst area of southwest China, the typical carbonate geomorphology is developed, such as the sinkhole, depression, cockpit, and cone, which further result in the barren and thin soil [15,16]. Thus, the karstic ecosystem, in particular river system is extremely sensitive and vulnerable due to the unique geological conditions and strong karstification [17,18]. In order to obtain more knowledge of karst fluvial hydrochemistry, this study presents the detailed investigation of river water stoichiometry and S isotope of Chishui River (a tributary of upper Yangtze River) watershed in southwest China karst region.…”

Section: Introductionmentioning

confidence: 99%

Sulfur Isotope and Stoichiometry–Based Source Identification of Major Ions and Risk Assessment in Chishui River Basin, Southwest China

Wang

et al. 2021

Water

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Hydrochemistry and sulfur isotope (δ34S–SO42−) of Chishui River watershed in Southwest China were measured to identify the sources of riverine solutes, the potential impact of human activities, water quality, and health risk. The main findings indicated that the HCO3− (2.22 mmol/L) and Ca2+ (1.54 mmol/L) were the major ions, with the cation order of Ca2+ (71 ± 6%) > Mg2+ (21 ± 6%) > Na+ + K+ (8 ± 3%) and the anion sequence of HCO3− (55 ± 9%) > SO42− (41 ± 9%) > Cl− (4 ± 3%). The riverine δ34S–SO42− values fluctuated from −7.79‰ to +22.13‰ (average +4.68‰). Overall, the water samples from Chishui River presented a hydrochemical type of Calcium–Bicarbonate. The stoichiometry and PCA analysis extracted three PCs that explained 79.67% of the total variances. PC 1 with significantly positive loadings of K+, Mg2+, F−, HCO3− and relatively strong loading of Ca2+ revealed the natural sources of rock weathering inputs (mainly carbonate). PC 2 (Na+ and Cl−) was primarily explained as atmospheric contribution, while the human inputs were assuaged by landscape setting and river water mixing processes. The strongest loadings of SO42− and NO3− were found in PC 3, which could be defined as the anthropogenic inputs. The H2SO4–involved weathering processes significantly impacted (facilitated weathering) the concentrations of riverine total ions. Sulfur isotope compositions further indicated that riverine SO42− were mainly controlled by anthropogenic inputs SO42− compared to the sulfide oxidation derived SO42−, and the atmospheric contribution was very limited. The results of risk and water quality assessment demonstrated that Chishui River water was desirable for irrigation and drinking purposes due to low hazard quotient values (<1, ignorable risk), but long–term monitoring is still worthy under the circumstances of global environmental change.

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“…The rainwater-related studies involved in various karst environmental types (urban, forest and agriculture) ( Wu et al, 2012 ; Xiao et al, 2013 ). In addition, under the unique geological background of karst landform (such as karst depression and sinkholes), rainfall dominates the migration of surficial material, which makes biogeochemical cycling more sensitive to rainfall event ( Qin et al, 2020 ; Wang et al, 2020 ; Xu et al, 2020 ; Yue et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Rainwater chemistry observation in a karst city: variations, influence factors, sources and potential environmental effects

Zeng¹,

Han²

2021

PeerJ

Self Cite

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The rainwater chemistry and related air contaminants are used to investigate the rainwater ions sources, variations, and influence factors from 2012 to 2014 in Guiyang city (the typical karst urban area of Southwest China). According to temporal rainwater ion concentrations, the obvious variations were presented in the study period, such as Ca2+ (125∼6,652 μeq L−1) and SO42− (11∼4,127 μeq L−1). Consequently, Ca2+, Mg2+, SO42− and Cl− are considered as the leading ions. Three critical influencing factors of rainwater ions concentrations, including sources variations, rainfall amount and long-distance migration (rainfall amount > 100 mm) are identified. Based on the typical ionic ratios, source identification suggested that anthropogenic inputs mainly contributed to F−, NO3− and SO42−, while the dusts (crustal sources) are the primary sources of Mg2+, Ca2+ and K+. Cl− Enrichment in long-distance transport is the main contributor of Cl−. According to the observation of high level of total wet acid deposition, the more detailed spatio-temporal monitoring of rainfall-related acid deposition (particularly sulfur deposition) is required to understand its potential environmental effects in the aquatic ecosystem of the earth surface.

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Rainfall driven nitrate transport in agricultural karst surface river system: Insight from high resolution hydrochemistry and nitrate isotopes

Cited by 81 publications

References 44 publications

Temporal Variations of Water Chemistry in the Wet Season in a Typical Urban Karst Groundwater System in Southwest China

Temporal Variations of Water Chemistry in the Wet Season in a Typical Urban Karst Groundwater System in Southwest China

Sulfur Isotope and Stoichiometry–Based Source Identification of Major Ions and Risk Assessment in Chishui River Basin, Southwest China

Rainwater chemistry observation in a karst city: variations, influence factors, sources and potential environmental effects

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