Spatio-temporal analysis of nitrogen and phosphorus in farmland water environments of Taihu Lake region

This paper analyzed changes in concentrations of nitrogen and phosphorus in farmland water environments in the Taihu Lake region over typical farming months of March, May and July. Results show high nitrogen and phosphorus pollution in the entire farmland water environment. A worsening trend is observed for the period of March to July. Nitrogen and phosphorus contents in surface water, especially in Taihu Lake, far exceed national eutrophication limits, with an acute pollution degree.Total-phosphorus (TP) and nitrate nitrogen (NO₃^--N) contents in well waters show obvious increase. As for ammonium nitrogen (NH₄⁺-N), it simply exceeds national type V standard of groundwater quality, very unfit for drinking. A negative linear correlation exists between NH₄⁺-N and clay content in shallow groundwater, and a positive linear correlation between NO^-₃-N and pH in deep groundwater.The results provide scientific-based decision-making tool for environmental protection and melioration drive of non-point source pollution in Taihu Lake region.