Pollution characteristics and risk assessment of surface sediments in nine plateau lakes of Yunnan Province

Sediment is the indicator of nutrient and heavy metal pollution in water environment, which can obviously reflect the pollution state in lakes. This paper reviews the literature of surface sediment pollution assessment of nine plateau lakes (Dianchi Lake, Erhai Lake, Fuxian Lake, Qilu Lake, Lugu Lake, Yangzonghai Lake, Yilong Lake, Xingyun Lake and Chenghai Lake) in Yunnan Province in the past ten years. TN (TN), total phosphorus (TP), copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), cadmium (Cd), nickel (Ni), arsenic (As), mercury (Hg) are selected. As an evaluation index, the average contents in surface sediments of nine plateau lakes were 3517.53 mg/kg, 1826.86 mg/kg, 72.52 mg/kg, 215.43 mg/kg, 39.51 mg/kg, 69.66 mg/kg, 1.31 mg/kg, 43.83 mg/kg, 12.77 mg/kg and 0.21 mg/kg, respectively. Nutrient and heavy metals in sediments were evaluated by single pollution index method, ground accumulation index method and potential ecological risk index method. The results showed that nutrient pollution was serious, and the average pollution level was heavy pollution. Eight kinds of heavy metals were in moderate or below the pollution level. Cd and Hg were the main contributing factors in the ecological risk assessment of heavy metals. The correlation analysis shows that the TN pollution in surface sediments of nine plateau lakes is related to the average water depth, recharge coefficient and population density of the lakes.