Article Dans Une Revue ACS ES&T Water Année : 2024

Isotopic Evidence of Denitrified Nitrate in Groundwater beneath Intensive Agriculture and Exchange with Estuary (Godavari, India)

Résumé

Nitrate is accumulated in the groundwater, modified through nitrification/denitrification, and exchanged with coastal/estuarine water bodies. To examine the sources and modifications of nitrate, the concentrations and isotopic composition of nitrate (δ 15N and δ 18ONO3) in the groundwater was monitored at 5 locations along the bank of Godavari estuary and in the estuarine waters for 7 months during wet (August–November) and dry (March–May) periods. Though the concentration of nitrate (NO3–) was higher during the wet than dry periods in both the groundwater and estuary, insignificant seasonal variability was observed in δ15N and δ18ONO3 indicating homogenization through mineralization–immobilization turnover of NO3–. The range of δ15N to δ18O of NO3– indicates soil, manure, and septic waste may be the major source of NO3–. The mean ratio of δ15N/δ18O of 1.1 ± 0.3 indicates the occurrence of denitrification in the groundwater. Concentrations δ15NNO3 and δ18ONO3 of NO3– displayed a significant relation between groundwater and estuarine water suggesting that NO3– is possibly denitrified. This study suggests that denitrified NO3– (enriched δ15N and δ18O) reported in the Godavari estuary may be contributed through submarine groundwater discharge than it is hypothesized to flux from the watershed.

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Dates et versions

hal-04737929 , version 1 (15-10-2024)

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Citer

B. Kumar, B. Sridevi, V. V. S. S. Sarma, Damien Cardinal, Mathieu Sebilo. Isotopic Evidence of Denitrified Nitrate in Groundwater beneath Intensive Agriculture and Exchange with Estuary (Godavari, India). ACS ES&T Water, 2024, 4 (8), pp.3521-3531. ⟨10.1021/acsestwater.4c00338⟩. ⟨hal-04737929⟩
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