Distribution Characteristics And Environmental Significance Of Surface Sediment Pigment Of Lake Bosten In Xinjiang

Lake Bosten was an inland freshwater lake in the northwestern part of China. Under the affection of natural and human impact, environmental conditions were changed in Lake Bosten. The study took Lake Bosten as a research object and measured the content of TOC(Total organic carbon), TN(Total nitrogen), CD(Chlorophyll derivatives), TC(Total carotenoids), NC(Native chlorophyll), Osc(Oscillaxanthin), Myx(Myxoxanthophyll) of sediment, by which we analyzed distribution characteristics, influential factors and sources to organic pigment. Then we explored the correlation among NC with pigment indexes. In the end the paper discussed the water quality, hoped to provide suggestions to prevent and monitor water pollution.(1) Spatial distributions of pigment content were different, CD changed from 2.4 to 6.1 units/g org., TC was 3.1～9.2 units/g org., NC was 10.8%～64.6%, Myx was 17.8～126.4 μg/g org., Osc was 20.0～281.5 μg/g org., CD/TC was 0.4-1.3 and Osc/Myx was 0.9～6.0.(2) The sources of pigment were a mixture of aquatic and terrigeous matter, excepted district I whose source maybe come from emergent aquatic plant. District II was dominated by phytoplankton or emergent aquatic plant, pigment of phytoplankton was dominated in district III, pigment of district IV was dominated by emergent aquatic plant. As the salinity was high in district V, terrigeous pigment was dominanted in the source.(3) According to PC A analysis, conductivity had an impact on spatial distribution of NC, and depth also affected distribution of Osc. The affection of pH to CD, Myx, CD/TC and depth to TC was low. The factosr influenced Osc/Myx weren’t found. Compared distributions of environmental factors with pigment content, Myx was influenced by combined effection of CODMn and pH, the variation trend of TC content and transparency was inverse. CD was a mixture of all style of chlorophyll, so its source was very complex, the influential factors remained to be solved in further study.(4) The correlation analysis between pigment content and NC found pigment indexes had no remarkable correlations with NC, which indicated the increase of primary productivity was the main factor controlled the pigment content rather than preservation condition. The negative correlation between CD/TC and NC accounted for preservation conditions was not the primary factor influnced CD/TC, which explained that Lake Bosten was not a oligotrophic lake to some extent.(5) The lake was in mesotrophic state. In district I water was clean and had high productivity District Ⅱ had lower productivity than district Ⅰ, the nourishment state became higher than district Ⅰ, which was affected by mobility and residence time of water. District Ⅲ had relatively high productivity, the water was in eutrophic status that was related to pollutant of human activities. The nourishment state of district IV was lower than district Ⅲ and in mesotrophic state and presented intensify eutrophic trend. District V located in the end of the lake, the stagnant water provided better preservation condition for pigment. In that area, the lake was in mesotrophic state, and had high salinity content made it have less blue-green algae, which indicated that cycling time of water had a crucial effect on entrophication in lakes.