Studies on Nitrogen,Phosphorus and Organic Matter in Ponds Around Chaohu Lake

There are a lot of ponds around Chaohu Lake.According to location and runoff supply of ponds,the ponds are divided into three types:ponds inner vellage (PIV),ponds adjacent vellage (PAV) and ponds outer vellage (POV).The samples of water and sediment were collected from 136 ponds around Chaohu Lake and the contents of nitrogen,phosphorus and organic matter in water and sediments were analyzed in this study.The results showed that mean contents of total nitrogen (TN),NH 4+-N,NO 3--N,NO 2--N,total phosphorus (TP),soluble PO34--P and COD were 2.53,0.65,0.18,0.02,0.97,0.38 and 51.58 mg·L-1 in pond water,respectively;and mean contents of TN,NH 4+-N,NO 3--N,NO 2--N,TP,inorganic phosphorus (IP),organic phosphorus (OP) and loss of ignition (LOI) in pond sediment were 1 575.36,35.73,13.30,2.88,933.19,490.14,414.75 mg·kg-1 and 5.44%,respectivly.The ponds of more than 90% peresented eutrophycation in the contents of total notrogen and phosphorus in water.The contents of TN and NH 4+-N in water and sediment of PIV were significantly higher than that of POV.And the contents of inorganic nitrogen in pond water and sediment displayed a following order:NH 4+-NNO 3--NNO 2--N.Data analysis indicated taht there was a significantly positive correlation between organic amtter and tototal nitrogen and phosphorus in water and sediment.The nitrogen,phosphorus and organic matter in ponds mainly sourced farmlands and village land surface.The contents of nitrogen,phosphorus and organic matter in ponds were affected by location and runoff supply of ponds.By retainning nitrogen,phosphorus and organic matter in runoff,the ponds can effectively decrease nutrient content into Chaohu Lake.