Identification of nitrate source in receiving water with dual \rmNO_3^- isotopes (δ(¹⁵N) and δ(¹⁸O))

Impacts of nitrate pollution on environment and on human health have attracted widespread attention．Accurate analysis of the sources of nitrate can effectively manage nitrate pollution．The dual \rmNO_3^- stable isotopes technology is relatively simple and accurate, and it has been widely used in the analysis of nitrate sources in surface water and groundwater．The eigenvalues of nitrogen (δ(¹⁵N)) and oxygen (δ(¹⁸O)) isotopes of potential sources were used here to identify assimilation, denitrification and nitrification that may affect traceability results．Relavant literature search indicates that eigenvalues increase with increasing temporal and spatial scales, leading to overlap of eigenvalues, which are not conducive to source traceability．In addition, δ(¹⁸O) values and δ(¹⁵N) values could directly reflect occurrence of related reactions．But in some cases, assimilation and denitrification may not be distinguished, and δ(¹⁸O) values produced by nitrification may not be unique．The current method for nitrate source analysis is well-accepted, but assurance of integrity and non-overlapping of nitrate sources is a prerequisite for accurate source quantification．Therefore, with application of δ(¹⁵N) and δ(¹⁸O) technology to source analysis of nitrate in lakes, we give some suggestions for future research．