Nitrate Contamination in the Groundwater and Associated Human Health Risk Assessment for Gaya District, Bihar, India

The study pertains to nitrate concentration in groundwater resources of the Gaya district, Bihar, India and its related health risk to the local population. Groundwater serves as the principal source of drinking water in the area. 40 representative groundwater samples were collected and analyzed for nitrate and other water quality parameters. The concentration of Nitrate (NO₃^-) in the groundwater of Gaya district varied from 1.62 to 155.6 mg/L and exceeded the Bureau of Indian Standards (BIS) permissible limits for drinking water in 30% of the samples. The elevated nitrate levels were predominantly attributed to agricultural activities. To evaluate the human health risks associated with groundwater, Hazard Quotient for nitrate (HQ_nitrate) were calculated using the United States Environmental Protection Agency method. The mean HQ_nitrate values were estimated to be 1.03, 0.89 and 1.65 for the male, female and child populace, respectively depicting considerable risk to male and child populace. In 67.5% of the samples, HQ_nitrate for children exceeded the safety threshold of 1. The study advocates significant health risks, especially to children in many parts of Gaya district due to high concentrations of nitrate in the groundwater. Judicial use of nitrogen-based fertilizers is suggested to prevent further contamination of groundwater. The concentrations of nitrate showed significant spatial variations Nitrate concentrations exceeded the drinking water standards in 30% of samples. Nitrate in groundwater may be attributed to agricultural sources. Hazard Quotients indicated substantial health risks, especially impacting children.

本研究聚焦印度比哈尔邦加耶地区地下水资源中的硝酸盐（nitrate）浓度及其对当地居民的相关健康风险。该区域地下水为当地居民的主要饮用水源。研究人员采集了40份具有代表性的地下水样品，对硝酸盐及其他水质参数开展检测分析。加耶地区地下水中的硝酸盐（NO₃⁻）浓度范围为1.62至155.6 mg/L，其中30%的样品硝酸盐浓度超出了印度标准局（Bureau of Indian Standards, BIS）规定的饮用水允许限值。硝酸盐浓度升高的主要成因是农业活动。为评估地下水相关的人体健康风险，研究采用美国环境保护署（United States Environmental Protection Agency, EPA）方法计算了硝酸盐健康危害商数（Hazard Quotient for nitrate, HQ_nitrate）。男性、女性及儿童人群的硝酸盐健康危害商数均值分别为1.03、0.89和1.65，表明男性与儿童人群面临显著健康风险。在67.5%的样品中，儿童的硝酸盐健康危害商数超过了1的安全阈值。本研究表明，加耶地区多数区域因地下水中硝酸盐浓度偏高，存在显著健康风险，尤以儿童群体为甚。建议合理施用氮肥，以防止地下水受到进一步污染。硝酸盐浓度存在显著空间异质性；30%的样品硝酸盐浓度超出饮用水标准；地下水中的硝酸盐主要来源于农业活动；健康危害商数结果显示存在显著健康风险，尤其对儿童群体影响较大。