Deciphering the nitrate sources and processes in the Ganga river using dual isotopes of nitrate and Bayesian mixing model

Kumar, Anurag; Ajay, Ajay; Dasgupta, Bibhasvata; Bhadury, Punyasloke; Sanyal, Prasanta

doi:10.1016/j.envres.2022.114744

Cited by 18 publications

(2 citation statements)

References 53 publications

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“…Confirming these suggestions, for the first time, we use stable isotopic techniques to demonstrate that agricultural fertilizers are the most dominant source of NO 3 − in the Ganges during the dry season. Our observations are partly in agreement with a previous study that identified synthetic fertilizers as the second most important source of nitrate during the post-monsoon (wet) season in the Ganges river basin using stable isotopic studies [52]. The absence of significant correlations between δ 15 N or δ 18 O of NO 3 − with the analyzed metals and ions suggests the limited influence of agriculture on the river's inorganic chemical composition.…”

Section: Nitrate Isotopic Compositionsupporting

confidence: 92%

Basin-Scale Geochemical Assessment of Water Quality in the Ganges River during the Dry Season

Sharma

Liang

Laskar

et al. 2023

Water

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Identification of sources and transport pathways of heavy metals and major ions is crucial for effective water quality monitoring, particularly in large river systems. The Ganges river basin, the largest and the most populous river basin in India, remains poorly studied in this regard. We conducted a basin-level analysis of major ions, heavy metals, and stable isotopes of nitrate in the Ganges during the pre-monsoon season to constrain the sources and quantify the inorganic chemical composition of the river during its lean flow. Bedrock weathering, anthropogenic interferences, water contribution through tributaries, and surface water-groundwater interaction were identified as the major driver of metal and ion variability in the river. Heavy metals showed the highest concentrations in the upper section of the river, whereas ionic loads were the most variable in the middle. We find a significant impact of tributaries on the metal and ion concentrations of the Ganges in its lower reaches. Isotopic analysis of dissolved nitrate suggested synthetic fertilizers and industrial wastes as the main sources. We find that the otherwise clean waters of the Ganges can show high ionic/metallic concentrations at isolated stretches (As: up to 36 µg/L), suggesting frequent monitoring in the source region to maintain water quality. Except for water collected from the Yamuna and Kannauj in the middle stretch and the Alaknanda and Rishikesh in the upper stretch, the WQI showed acceptable water quality for the sampled stations. These findings provide an insight into the modifications of dissolved inorganic chemical loads and their sources in different sections of the basin, needed for mitigating site-specific pollution in the river, and a roadmap for evaluating chemical loads in other rivers of the world.

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Section: Nitrate Isotopic Compositionsupporting

confidence: 92%

Basin-Scale Geochemical Assessment of Water Quality in the Ganges River during the Dry Season

Sharma

Liang

Laskar

et al. 2023

Water

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“…Ji et al (2022) used the SIAR model to quantify the contribution of NO 3 − sources in the Wenruitang River Basin of China, and determined that urban sewage was the main source of NO 3 − (58.5-75.7%), followed by nitrogen fertilizer (8.6-20.9%) and soil nitrogen (7.8-20.1%), and atmospheric deposition was (<0.1-7.9%) (Ji et al, 2022). Furthermore, the Bayesian stable isotope mixing model was also applied to reveal the source contributions of nitrate in the Ganga river (Kumar et al, 2023), the western coast of Guangdong Province, South China (Lao et al, 2019), East China Sea (Wang et al, 2023), a rural karst basin in Chongqing, southwestern China (Chang et al, 2022), Han, Rong and Lian river basins (Ye et al, 2021), and the eastern coast of Hainan Island (Chen et al, 2020a). Chen et al (2020a) uesd the dual isotopes and some ion tracers to study NO 3 − sources and watershed denitrification.…”

Section: Determining the Nomentioning

confidence: 99%

Using dual stable isotopes method for nitrate sources identification in Cao-E River Basin, Eastern China

Sun

Lei

et al. 2023

Front. Environ. Sci.

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Excess nitrate (NO3−) of water is a worldwide environmental problem. Therefore, identifying the sources and analyzing respective contribution rates are of great importance for improving water quality. The current study was carried out to identify the potential sources of NO3− pollution in Cao-E River basin, in Eastern China. Surface water samples were collected during the dry season and wet season. Multiple hydrochemical indices, dual NO3− isotopes (δ15N–NO3− and δ18O–NO3−) and a Bayesian model (stable isotope analysis in R, MixSIAR) were applied to identify NO3− sources and estimate the proportional contributions of multiple NO3− sources. During the sampling period, nitrification was a dominant nitrogen transformation process in the study area. The results of the NO3− isotopes suggested that manure and sewage (M&S), soil nitrogen (SN) and nitrogen fertilizer (NF) were the major contributors to NO3−. Moreover, the results obtained from the MixSIAR model showed that the proportional contributions of atmospheric deposition (AD), NF, M&S and SN to NO3− were 2.82, 15.45, 44.25, 37.47% and 3.14, 23.39, 31.78, 41.69% in the dry and wet season, respectively. This study provided evidence to further understand the sources, transport, and transformation of N in Cao-E River basin, which deepens the understanding of the management of N contaminant.

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Long-term variations (1970–2020) and spatial patterns of nitrogen and phosphorus soil budgets and fates in Indian agriculture

Elsayed,

Beusen,

Prusty

et al. 2024

Nutr Cycl Agroecosyst

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The Green Revolution rapidly increased India’s food production since the 1960s, but excessive synthetic fertilizer use caused severe environmental problems. Our spatially explicit analysis for 1970–2020 indicates an uneven distribution of the dramatic increase of surpluses of India’s soil N (4.3 to 21.6 Tg N/year) and P budget (0.4 to 3.3 Tg P/year): with high surpluses in e.g., Green Revolution (GR) and South-West (SW) regions, lower surpluses in e.g., North-West (NW) and even local deficits within some other states Nutrient surpluses were growing primarily through increased use of synthetic fertilizers, which resulted in declining nutrient use efficiency, high N and P losses and soil P accumulation, with large regional heterogeneity. Total N loss is determined by the surplus, through “holes in the pipe”, whereby the holes (loss pathways) differ in diameter, as determined by climate, crop, soil, terrain and management. Ammonia volatilization ranged from 16% of the N surplus (NC) to 45% (GR states), and denitrification losses from 50% (NC and SW) to 38% (GR) and 28% (NE). N loss via leaching ranged from 46% (NE), to 22–26% (GR and NC), and 16% (SW), and surface runoff losses between 2% (GR) and 9% (NC). In the period 1970-2020, our estimated soil P accumulation across India amounts to 290 kg P/ha, highest in SW followed by NE and GR states and lowest in NC. The SW region also has the highest surface runoff P loss (40% of its regional budget), followed by NC (53%), NE (34%), and GR (26%). Addressing these regional differences can help developing effective, targeted and region-specific nutrient management strategies while meeting India’s rising food demand.

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Deciphering the nitrate sources and processes in the Ganga river using dual isotopes of nitrate and Bayesian mixing model

Cited by 18 publications

References 53 publications

Basin-Scale Geochemical Assessment of Water Quality in the Ganges River during the Dry Season

Basin-Scale Geochemical Assessment of Water Quality in the Ganges River during the Dry Season

Using dual stable isotopes method for nitrate sources identification in Cao-E River Basin, Eastern China

Long-term variations (1970–2020) and spatial patterns of nitrogen and phosphorus soil budgets and fates in Indian agriculture

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