Study On The Characte Ristics Of Iron And Manganese Pollution In Lakeshore Groundawater Of Dongting Lake

Groundwater pollution is one of current hot research field in waterenvironmental protection, heavy metal pollution of the groundwater become aresearch focus because of its long-term, cumulative and difficult to governance.Lakeside plain have characteristics of thea flat topography, abundant water suppliesand densely populated, but very little research have been involved in view of thelakeside plain groundwater pollution characteristics and health risk assessment. Basedon the typical-dongting lake lakeside plain Chengxi town as the study area, In thispaper analysis of the current situation of heavy metal pollution of groundwater andprobes into the spatial and temporal, enrichment characteristics and health risks of theiron and manganese. In order to further promote the safety of drinking water in thestudy area and help the local government will provide a scientific basis for waterconservation policy.(1) The pollution status of various heavy metals in the groundwater was studiedwith the help of comprehensive identification index based on entropy weight modelsystem and the sensitivity of the comprehensive evaluation results to each evaluationfactor. And a comparative study was carried out according to the evaluation results ofdifferent evaluation methods. The results showed that three heavy metals including Pb,Fe, Mn had a higher pollution index and constituted the major metallic pollutants inthe groundwater of Dongting lake district. The contamination rate of the heavy metalsFe, Pb and Mn reached86.67%,80.00%and70.00%based on the GB/T14848-1993《water environment qualitystandards of groundwater》qualityof class Ⅲ.The worstwater quality were Case V, Case IV and inferior Case V. And the pollution index ofwaters studied was3.982, belonging to Case Ⅲ. The results of comprehensiveevaluation had a good sensitivity to Pb and Mn, whose sensitive coefficients were0.2925and0.2406respectively.(2) The research of the spatial and temporal distribution and enrichment of theiron and manganese show that iron rendered plaque shape distribution and manga neserendered plaque shape and planar distribution in the study area of the groundwater.The iron had obvious concentration difference in the plentiful. Alkaline environmentwas′t conducive to the enrichment of the iron and manganese. The iron showed thecentral region from wind to gradually reduce the trend and the iron concentration inthe Midwest was higher than the eastern region of the Chengxi town. Each area of therion contented peesent a trend that Chengxi town internal＞the west tributary＞theDongting lake district＞the east tributary. The manganese rendered plaque shape and planar distribution. The Chengxi sampling area of the manganese was the high levelsand the others sampling areas were the state of the lighe pollution. Each area of themanganese contented peesent a trend that the east tributary＞the Dongting lakedistrict＞Chengxi town internal＞the west tributary. The iron and manganeseelements were concentration difference apparent in different season and the trend forthe mutagenicity＞the level period＞the plentiful.(3) Through the health risk assessment of the iron and manganese discovered thatthe health risks of the iron and manganese were difference in time and space. Fromthe analysis of seasonal change would be founded the rion, the manganese and theiron and manganese comprehensive risk value rendered the trend for the mutagenicity＞the level period＞the plentiful. Analysis of the change from the space that eachperiod of comprehensive risk value were particular in the Chengxi sampling area. Thevalue of the risk were high in the Shunfeng sampling area, Hejia sampling area andJinxing sampling area. Each area of the manganese contented peesent a tre nd that theeast tributary＞Chengxi town internal＞the Dongting lake district＞the westtributary.