SEDIMENTARY RECORD OF NUTRIENT ACCUMULATION RATES IN CORE ZS FROM TAIHU LAKE FOR RECENT 50 YEARS

The Taihu Lake drainage basin is an economically developed area among the highest population densities in China. The lake has been deteriorated due to ecological destruction and eutrophication. Core ZS dated by ²¹⁰Pb or ¹³⁷Cs method from Zhushan Bay of Taihu Lake were collected. Nutrients including TOC (total organic carbon), TN (total nitrogen), and TP (total phosphorous) were analyzed for the purpose of understanding nutrient change. ¹³⁷Cs activities were low (less than 15 Bq/kg) in core ZS. The sedimentation accumulation rates ranged from 0.13 to 0.75 g/cm²/a at core ZS based on CRS model. A remarkable increase in nutrient accumulation rates since the early 1980s occurred in the core. The historical change of nutrient accumulation rates observed in cores concoined with monitoring data for surface sediment since 1960s. TP flux after early 1980s was 0.91 times higher than rates calculated between 1950s and 1970s in core ZS. It was concluded that higher TP accumulation rates in very recent deposits of Taihu Lake resulted from both diagenetic factors and human activities.