中国乌达煤炭基地尘土汞分布特征

Distribution of mercury content in dusts of coal base,Wuda,China

针对乌达区约200km^2的区域按照1km网格法在185个点位采集了约1.5mm厚度的地表尘土样.热解-Lumex RA-915汞分析仪对其测试结果表明:煤矿区尘土汞含量范围117~765ng/g,平均值为285ng/g;工业园尘土汞含量范围160~6453ng/g,平均值为804ng/g;城区尘土汞含量范围41~382ng/g,平均值为160ng/g;农场尘土汞含量范围16~198ng/g,平均值为66ng/g;荒地尘土范围3~284ng/g,平均值为50ng/g.乌达区尘土汞分布具有显著的非均一性.与乌达区背景值(18ng/g)和中国潮土背景值(50ng/g)相比较,乌达工业园和煤矿区尘土汞明显富集.与国内金属矿区、城区尘土Hg含量相比,乌达煤矿区、城区尘土Hg含量较低;煤矿区尘土汞与煤火区、矸石山相对位置和本身地势有关;城区位于煤矿区下风向,受煤矿区煤火影响,植被稀少、空气干燥和夏季日照较长成为制约汞沉降的主控因素;工业园区的极大值点可能与区域地理位置和PVC生产相关.通过计算Igeo值,发现乌达区工业园污染严重,偏重污染区域占全区36.59%,7.32%达到极重污染程度;煤矿区多为偏中污染和中污染,在全区所占比例为84.09%,偏重污染区域仅为2.27%;城区、农场和荒地污染较少.

185samples were collected,using a systematic sampling strategy with sampling density3composite dustsamples(about1.5mm above the ground surface)per km2in Wuda,and total of200km2.The mercury(Hg)concentrations of dusts were investigated using Lumex RA-915.The results showed that the dust Hg concentrations ofcoalfield ranged from117to765ng/g with an average of285ng/g,the value of industrial part ranged from160to6453ng/g with an average of804ng/g,the value of urban ranged from41to382ng/g with an average of160ng/g,the valueof farm ranged from16to198ng/g with an average of66ng/g,and the value of industrial wasteland ranged from3to284ng/g with an average of50ng/g.Compared with the value of Wuda background and China tide soil background,thedust Hg concentrations were significantly enrichment in industrial park and coalfield.But the concentrations were lowerthan that of metal mining area and other urban,the reason of which was that the dusts mercury was mainly related to therelative position of coalfire,gangue and it’s geographic height in coalfield,sunshine duration,dry air and surface naked inurban.The distribution of dust Hg in Wuda was significantly inhomogeneity.The Hg distribution in industrial park wasaffected by regional humidity increase,chemical plant using the involving mercury catalyst and regional geographicallocation such as relatively closed and downwind of coal-fired power plants.By the analyze of geo-accumulation index(Igeo),the results showed that the Hg pollution of industrial park was serious with36.59%area close to heavy pollutionand7.32%very heavy pollution,the Hg pollution in coalfield was moderate with2.27%area close to heavy pollution,other areas were lesspolluted.