HUMAN IMPACT RECORDED IN THE SEDIMENT OF HONGHU LAKE

Two short sedimentary cores were collected from Honghu lake named HN and HS. The total or- ganic carbon, total nitrogen, phosphorus, susceptibilities, elements and partial size were analyzed. Combi- ning with137Cs dating, the results indicated that nutrient evolution succession of historical period can be di- vided into three stages. Before 1840 the lake was characterized with lower productivity, during about 1840 ~1950 there was an obvious increase of organic production because of population increase. Since 1950, hu- man impacts have accelerated the lake′s trophic status. Large amounts of carbon, nitrogen, phosphorus have accumulated in the sediment. The accumulation of these nutrients is considered to be the discharge of sewage water from multiple sources and cultivation of the lake. The comparison of indices of the two cores shows that district difference does exist due to the inlet water flow, matter source and human impacts. It can be concluded that the human impacts have greatly disturbed the process of natural environmental evo- lution of Honghu lake.