Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6329031 | Science of The Total Environment | 2014 | 10 Pages |
Abstract
Water pollution in the form of nitrate nitrogen (NO3â-N) contamination is a major concern in most agricultural areas in the world. Concentrations and nitrogen and oxygen isotopic compositions of nitrate, as well as oxygen and deuterium isotopic compositions of surface and groundwater from a typical irrigated region in the North China Plain (NCP) collected from May to October in 2012 were analyzed to examine the major nitrate sources and transformations. Concentrations of NO3â-N ranged from 0.2 to 29.6Â mg/L (mean of 11.2Â mg/L) in surface water, and from 0.1 to 19.4Â mg/L (mean of 2.8Â mg/L) in groundwater. Approximately 46.7% of the surface water samples and 10% of the groundwater samples exceeded the World Health Organization (WHO) drinking water standard for NO3â-N. Surface water samples that exceeded the standard were collected mainly in the dry season (May and October), while groundwater samples that exceeded the standard were collected in the wet season (June). Overall, the highest nitrate levels were observed in surface water in May and in groundwater in June, indicating that fertilizer application, precipitation, and irrigation strongly influence the NO3â-N concentrations. Analyses of isotopic compositions suggest that the main sources of nitrate are nitrification of fertilizer and sewage in surface water, in contrast, mineralization of soil organic N and sewage is the groundwater sources during the dry season. When fertilizers are applied, nitrate will be transported by precipitation through the soil layers to the groundwater in the wet season (June). Denitrification only occurred in surface water in the wet season. Attempts should be made to minimize overuse of nitrogen fertilizers and to improve nitrogen use efficiency in irrigated agricultural regions.
Keywords
Related Topics
Life Sciences
Environmental Science
Environmental Chemistry
Authors
Yan Zhang, Fadong Li, Qiuying Zhang, Jing Li, Qiang Liu,