Groundwater Nitrogen Pollution and Assessment of Its Health Risks: A Case Study of a Typical Village in Rural-Urban Continuum, China

Abstract

Protecting groundwater from nitrogen contamination is an important public-health concern and a major national environmental issue in China. In this study, we monitored water quality in 29 wells from 2009 to 2010 in a village in Shanghai city, whick belong to typical rural-urban continuum in China. The total N and NO₃-N exhibited seasonal changes, and there were large fluctuations in NH₄-N in residential areas, but without significant seasonal patterns. NO₂-N in the water was not stable, but was present at high levels. Total N and NO₃-N were significantly lower in residential areas than in agricultural areas. The groundwater quality in most wells belonged to Class III and IV in the Chinese water standard, which defines water that is unsuitable for human consumption. Our health risk assessments showed that NO₃-N posed the greatest carcinogenic risk, with risk values ranging from 19×10⁻⁶ to 80×10⁻⁶, which accounted for more than 90% of the total risk in the study area.