Jin XiangCan

Spatial-temporal variations of aquatic environmental factors and their influences to algal blooming in Lake Chaohu

In order to understand the interactions between environmental factors and the algal biomass in Lake Chaohu,those relatively important environmental factors to alga biomass were extracted.Based on monitored water quality data of Lake Chaohu in 2008,cluster analysis,discriminate analysis and the recognition of pollution feature were carried out to reveal the relationships between water environment factors and algal biomass.Results suggest that the Lake Chaohu can be divided into severe polluted area,moderately polluted area,and mildly polluted area from west to east.The Chl.a and dissolved total nitrogen are the indicative factors describing the significantly spatial difference in water environment.The sequence of pollution classification for all the monitoring sites are as follows: Nanfei river inlake areaShiwuli river inlake areaTangxi river inlake areaWest lake center areaPaihe river inlake areaHangbu river inlake areaZhongmiao areaZhaohe river inlake areaBakou areaEast lake center areaShip factoryZhonghan town area.The screened important environmental factors to algal biomass vary with seasons.TP,TN,temperature,NO-3-N and NH+4-N are closely related to algal biomass all the year round.

Humus distribution and forms in the sediments from shallow Iakes in the middle and lower reaches of the Yangtze River

The organic matter(OM) content,compositions and fractions of shallow lake sediments were studied by chemical method from in the middle and lower reaches of Yangtze River.The results showed that the OM content varied greatly from 0.98% to 11.0 %,higher in the heavily polluted sediments than those in the light polluted ones.The distributions of OM content were closely related to lake pollution levels and human activity intensity.HA content was 1.03-6.73g/kg,and FA content is higher than the HA,from 2.73 to 9.77g/kg.Humin was the main fractions of humus,varing from 5.89 to 55.57g/kg.PQ(HA/(FA+HA)) ratio varied from 23.04% to 50.56%,and the mean content of PQ was 32.72%.PQ content were higher in the heavily polluted sediments than those in the light polluted ones,which indicated that there was a higher degree of humification in heavy polluted sediments.Combination of three kinds of humus content in the form of tightly bound humus content was the highest,and content was 3.21-47.76g/kg;followed by loosely combined humus content between 0.86-6.92g/kg.The stable combined humus were the lowest,the content varied from 0.72 to 3.89 g/kg.The loose/tight ration in the sediments were also negatively correlated with OM,TP and TN,which showed that heavily polluted shallow lakes had higher humification and humus accumulation.So humus should be paid more attention to the carbon cycling and eutrophication control in lakes.

Characteristics and evaluation of As pollution in the sediments of medium-small scale lakes in Lake Dongting Plain

Spatial distribution of arsenic(As) concentrations of sediments collected form ten medium-small scale lakes in Lake Dongting Plain was investigated,and the As pollution degree was evaluated using the geo-accumulation index.Average value of As sediment concentration from 10 lakes was 15.8 mg/kg,which varied from 10.1 to 33.7 mg/kg.It indicated that As sediment contamination was relative low.As to spatial distributions,the average contents of As in the superficial sediments were from high to low in the sequence of Yueyang South Lake,Bajiao Lake,Huanggai Lake,Anle Lake,Maoli Lake,Liuye Lake,Dong Lake,Shanpo Lake,Datong Lake,and Beimin Lake.As concentrations in the lake basins were from low to high in sequence of Lishui catchment(13.1mg/kg),Ouchi catchment(13.4mg/kg),Yuanshui catchment(16.2mg/kg),and lakes at outlet areas of Dongting Lake(22.4mg/kg).Degree of As pollution in lake sediments aggravated gradually from the upstream to the downstream of Lake Dongting drainage.Sediment sample analysis from 4 cores(Datong Lake,Huanggai Lake,Bajiao Lake and Shanpo Lake) showed that As had accumulated in sediments and increased from the bottom to the surface(30-0cm).Geo-accumulation index analysis showed that pollution level at 22 sites from eight lakes were none,and 7 sites from five lakes were at Level I.As a whole of Lake Dongting drainage,As pollution level in the superficial sediments was low.