| Sediment is not only the reserve of pollutants, but also the potential source of pollutants which has influence on environment. Recently, the issue of heavy metal bioavailability of aquatic sediments is becoming one of the popular matters in the research of heavy metals in water environment.This study chooses Lake Chaohu in Anhui as my research object. The total metals of seven kinds of heavy metals(chromium, lead, copper, nikel, zinc, cadmium, arsenic), acid volatile sulfide (AVS), the simultaneously extracted metals (SEM), organic matters and water content which are main physical and chemical indices have been analyzed. It is found that the characteristics of distribution, the relationship and the possible source of heavy metals by many methods of assessment of heavy metal pollution of sediments. The pollution of heavy metals and trend have been also analyzed. Heavy metal bioavailability of aquatic sediments has been estimated by the models includeing [SEM-AVS],[SEM]/[AVS] and [SEM-AVS]/fOC.The features of plane distribution, vertical distribution and seasonal distribution of AVS and SEM, along with influence factors have been preliminarily discussed. Results have been obtained as follows.(1) Average contents of heavy metals in surface sediments in the easthern part of Lake Chaohu are slightly lower than those in the western part. Enrichment degree of elements in surface sediments of Nanfei-Dianpu Estuary is the highest in Lake Chaohu. Compared with historyical data, average contents of chromium, copper, cadmium and arsenic in sediments have been trending upward year afer year, which in 2007 are respectively 2.9,2.8,2.4,3.8 times more than data in 1986.(2) The evaluation of seven kinds of heavy metals in surface sediments of Lake Chaohu with the method of potential ecological risk assessment shows that potential ecological risk is low, but relative potential ecological risk index is 349.1.Grade for relative ecological risk factor is high. Especially relative pollution of cadmium is serious and grade for ecological risk factor is high(relative potential ecological risk index is 276.2).The evaluation of seven kinds of heavy metals in surface sediments of Lake Chaohu with the method of geoaccumulation assessment shows that geoaccumulation is 1 which belongs to slight pollution. Geoaccumulation of cadmium is 3,which belongs to moderate pollution.(3) The concentration of AVS is high in surface sediments of Lake Chaohu(0.13～16.53μmol·g-1).High concentrations of AVS have been recorded in the Shiwuli Estuary and the Yuxi Estuary. The distribution of AVS varies in space in different seasons in Lake Chaohu. The variation in spring is the greatest. The variation in winter takes the second place, and the variation in autumn takes the third place. Through correlation of AVS,SEM and POC in surface sediments in different seasons, the results shows significant positive correlation between temperature and AVS.When the temperature is high, the concentration of AVS is high. It shows that AVS plays important role in controlling heavy metal bioavailability of aquatic sediments when the temperature is high.(4) The distribution of SEM varies in space in different seasons in Lake Chaohu. The variation of SEM in winter is the greatest. The variation in sping take the second place, and the variation in autumn take the third place. High concentrations of SEM have been recorded in the Nanfei-Dianpu Estuary and diffuseion region(0.33-5.78μmol·g-1).(5)The range of SEM-AVS,SEM/AVS and ([SEM]-[AVS])/fOC is respectively-10.84～1.22μmol·g-1,0.08～9.57 and below 150μmol·g-1 (OC).The assessment result shows that indication of associated adverse effects in suface sediments in most areas of Lake Chaohu is low.
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