Spatial And Temporal Distribution Of Gaseous Elemental Mereury And Emission From Anthropogenic Sources In Yunnan Plateau

Mercury can cycle and transform among the atmosphere,land and ocean because of its special physical and chemical properties.Mercury can not only deposit near the sources,but also can transport to long distance with air and passes the pollution on to other areas.In recent years,anthropogenicemissions of mercury appear to decrease in Europe and America while increase in Asia.There are more and more researches about coastal cities or remote areas in China.Compare to the researches were made in the coastal cities or remote areas,the researches of atmospheric mercury in southwest plateau cities are less.There are more mineral resources in Yunnan,a large amount of mercury is discharged from smelting activities,and affecting the human health seriously.It is important to improve the quality of air and protect the health of the population by conducting research on atmospheric mercury monitoring in related areas.In this study,we collected the gaseous mercury samples in environment during April 2016 to April 2017,and collected samples in Kunming(Dongfeng Tung Road.New Lion Bay and Xishan Forest Park)in March 2017.Gaseous mercury from anthropogenic was collected on gold coated sand quartz tubes.Industrial pollution sources samples were collected in Kunming,Yuxi,Wenshan and Baoshan during June 2015.August 2015 to September 2015 and October 2016 to November 2016.The biomass burning and anthracite combustion in civil and coal-fired furnace and vehicle emissions samples were collected during August 2016 to September 2016.The anthropogenic source sample by dilution channel and two-stage gold amalgamation combined with sampling.The objects of this study were to analysis the temporal and spatial distribution of gaseous mercury in the environment and discuss the pollution characteristics of anthropogenic emission sources.The main conclusions are as follows:(1)The average concentration of sgaseous elemental mercury was 4.02±1.86ng/m~3 in Kunming from 2016 to 2017.The seasonal variation of gaseous elemental mercury was summer>autumn>winter>spring.The measurements showed the concentration of gaseous elemental mercury was generally higher than that at nightin the four seasons was higher than that of nighttime.The spatial variation characteristics of GEM was business area(the new snail Bay)>traffic area(Dongfeng Tung Road)>culture and education area(Faculty of environmental science and engineering)>clean area(Xishan Forest Park).(2)GEM was closely related to meteorological factors during sampling period in Kunming.Due to the high concentration of ozone and other oxides,the gaseous element mercury is prone to oxidation reaction,resulting in a lower gaseous mercury concentration during the sampling period.The gaseous mercury concentration will increase in summer,autumn and winter with theincrease of light intensity and temperature,the process of photoreduction and microbial reduction of atmospheric mercury were enhanced.GEM concentration had a negative correlation with temperature and positive correlation with relative humidity in spring;GEM concentration had a positive correlation with temperature and negative correlation with relative humidity in other seasons.(3)The concentration of gaseous mercury increased at the beginning of the rainfalls.Because of the soil porosity increasedU the Hg0 release from the soil surface and the Hg2+ produced by the photolysis reduction of Hg0.And persistent rainfall would result in decrease of mercury emission flux and the concentration of GEM.Because of the migration ability of mercury was reduced with the decrease of the temperature and the soil pore is blocked when the soil water content is too high.(4)In this study,the concentration of mercury in the flue gas of anthracite coal was 7.44～9.29μg/m~3;the concentration of mercury in the flue gas of biomass was 2.14～4.23μg/m~3;the average mercury concentration of the anthracite coal was 0.12mg/kg;the average mercury concentration of biomass was 11.95μg/kg.(5)The concentration of mercury of gasoline vehicle exhaust was 0.6～0.9μg/m~3;the concentration of mercury of diesel vehicles exhaust was 1.3～2.2μg/m~3;the concentration of mercury of bus exhaust was 2.03～3.01μg/m~3;the concentration of mercury of truck exhaust was 34～4.6μg/m~3.(6)The mercury emission coefficient of flue gas in industrial boiler is about 53μg/kg,and the mercury emission coefficient of flue gas in industrial boiler is approximately 73.23mg/t.The mercury emission coefficient of boilers in coal-fired boiler is approximately 35.42mg/t;the mercury emission coefficient of flue gas in industrial boiler is approximately 6.15g/t;the mercury emission coefficient of flue gas in industrial boiler is approximately 89.44mg/t;the mercury emission coefficient of industrial boiler flue gas is approximately 2.36mg/t.(7)The average flue gas mercury concentration of cement plant was 3.32μg/m~3;the flue gas mercury emission factors of kiln tail was 21.3mg/t with FF and SCR,the flue gas mercury emission factors of kiln was 3.50mg/t with FF.the flue gas mercury emission factors of kiln tail was 15.87 mg/t.The flue gas mercury concentration of Sintering flue gas,blast furnace and converter were respectively 4.5μg/m~3.14.4μg/m~3 and 18.0μg/m~3.The flue gas mercury emission factors of crude steel was 0.34g/t.(8)According to the Yunnan Statistical Yearbook-2015,the coal consumption of tobacco production,the consumption of medical and pharmaceutical products,cement production,crude steel production,the mercury emissions of tobacco production was 22.68kg,the mercury emissions of medical and pharmaceutical products was 0.3kg,the mercury emissions of cement production was 1.40t,the mercury emissions of crude steel production 1.86t in 2015.