Groundwater nitrate contamination in agroecosystems: A comprehensive review of detection methods, pollution mechanisms, and policy implications

The present study focuses on the nature and extent of groundwater nitrate contamination, especially in the agroecosystems. This comprehensive review also examines the detection methods, pollution mechanisms, and policy implications. Therefore, the study reveals novel findings based on the Scopus database of 168 articles from 1991 to 2023. The bibliometric analysis using “VOSviewer” unfolds progress in nitrate investigation in terms of keyword occurrence, leading journals, and leading authors in the concerned field. Additionally, methods for detecting nitrate through electrochemistry, electricity, and spectroscopy are discussed. Taking all into account, this study concludes that field-effect transistor (FET) sensors are the best option out of the sensors covered. Various methods, including HYDRUS-1D and 2D, MODFLOW and MT3DMS, RT3D, and PHT3D can be used to assess the different sources responsible for nitrate contamination in groundwater. Nitrate may be removed from groundwater using one of two techniques-reduction or separation. Several novel approaches are presented, and the utilization of these technologies for nitrate removal is discussed in this study. Furthermore, the advantages and disadvantages of each approach are evaluated critically. Finally, in light of our growing understanding of the problem, some suggestions are provided.