Pollution Characteristics and Evaluation of Surface Sediment of Nanhu Lake

Twelve samples of surface sediment in Nanhu Lake, Wuhan city were collected and the concentrations of Organic Matter (OM), Total Nitrogen (TN), Total Phosphorus (TP), ammonia nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃^--N) were determined; the average result were 6.58%, 3972, 1712, 897 and 20mg/kg separately. Cd, Hg, As, Cu, Pb, Cr and Zn were determined too; and the average value were 0.46, 0.140, 19.3, 45.8, 57.3, 53.3 and 90.3mg/kg respectively. The content of pH, TN, TP and NH₄⁺-N in overlying water and pore water were tested, the concentrations of TN and NH₄⁺-N were higher and TP were less in pore water than that in overlying water, which meant that TN and NH₄⁺-N in sediment could release into water and TP couldn´t. The contaminants values of surface sediment near the biggest sewage outlet were much higher than that of others. When evaluating the surface sediment with organic index and organic nitrogen and pollution load index, the results showed organic pollution was heavy and heavy metals pollution was moderate.