| As a global pollutant, atmospheric mercury has been attracting more and more attention and many countries has established a series of measures to control it.ChongQing is an industrial city with long history. Coal is the main energy source. A lot of coal combustion and bad diffusion condition make a city with heavy air pollution. According to related research, coal combustion is an important anthropogenic source of atmospheric mercury. In the meantime, ChongQing locates at the upper Yangtze river so that its pollutants will directly affect the water quality of the Three Gorges Reservoir. So, atmospheric mercury contamination is an interesting question in Chongqing. This paper is to discuss the transference and transformation of mercury and estimate the regional capacity by monitoring the discharge and deposition situation of atmospheric mercury.The whole research is divided into four parts: pollution source, atmospheric mercury, mercury recycle in the catchments and mercury in soil.The source pollution monitoring was done to Jiulong Power Plants and Chongqing Power Plants. According to the data, the discharge amount per year is about 1063.06kg/Y, higher than the calculated data using discharge factors. That is because of the concentration of mercury in coal, the combustion situation, dust catcher and so on. The estimated mercury discharge amount of ChongQing in 2004 was about 13.03 tons, much more than the amount in 2001.this may be the result that the increasing trend of coal combustion is higher than the increasing rate of the waste gas treatment.The monitoring of particulate mercury in atmosphere was done at GYQ and TISP in different seasons. The average volume concentration was 0.052-0.902 ng/m~3 at TISP and 0.033—1.817 ng/m~3 at GYQ. Estimated by the proportion of particulate mercury, the total atmospheric mercury concentration is 2.83-5.66ng/m~3 at TISP and 5.49-10.98 ng/m~3 at GYQ. No matter particulate mercury or total atmospheric mercury, the concentration were both higher than the related research results, which mean ChongQing city, especially the downtown has been enduring the mercury pollution. From the time-concentration curve, the concentration distribution at TISP was Winter>Autumn>Spring>Summer and at GYQ is Winter>Spring>SummeP=Auntumn.The different trends said that in Winter,the worse diffusion condition and higher concentration led higher concentration around the source. And for GYQ, the higher particle and volatilization speed was reason of higher concentration in Spring and Summer while for TISP, the abstraction of leaves was one of the key reasons. Temperature is negative related to the concentration of mercury and total suspended particle while the volume concentration of mercury is positive related to TSP concentration. Wet deposition tension is negative with mercury volume concentration but positive related to the weight concentration. The concentration at night is higher than in the daytime. Using model to estimate the dry deposition fluxes, the results showed 39.39ug-(m2-a)'1 flux at TISP and 89.22ug-(m2-a)"1 at GYQ.The monitoring of mercury recycle at TISP catchment and GYQ showed, all of the indexes (mercury concentration and fluxes in bulk deposition, through fall, litter fall, runoff and soil) were higher than the background value and the values in other areas. That indicated mercury pollution in some degree. As to the timely concentration distribution, the higher concentration of bulk deposition and through-fall exist in Autumn and Winter while for litter-fall it occurs in Autumn. At GYQ, the peak value of litter-fall also existed. As for the time-flux series, the peak value was in September and since September to February next year;the value kept decreasing and decreasing again since April.The through-fall and litter-fall are the main component to the total input fluxes. At different sites, the contribution proportion changes. At TISP, the through-fall is more important and at GYQ, litter-fall is more important. For output fluxes, the runoff just take 4.0% of the total flux, that is to say most part of mercury is retained in soil and being potential pollution source.The dry deposition flux calculated by net through-fall (NTF=TF-BD) was higher than calculated using paniculate mercury concentration. That may be the result of two reasons: first, the dry deposition rate is rfct fit for all the areas;second, as the BD also contains part of dry deposition, the result may be smaller than reality. Despite all this, the variance and importance of dry deposition are the same. At TISP, the NTF is much lower than TF while at GYQ, the two are nearly the same. That means at TISP, fine particle is the main source while at GYQ, the coarse particle is also very important. So the local pollution sources affect the urban area much higher than rural area. As for soil at catchment, the profile shows the highest concentration is in layer O and A, which is concerned with the more organic materials in the two layers.Mercury in soil was investigated according to the different use zoning .the data shows that the average concentration is 0.31 mg/kg. The enrichment coefficient is 7.75, far higher than 1. Both of these means the serious pollution and reflects the affection of atmospheric deposition. The soil affected by area source is with much higher concentration than by liner and point sources. For point source , that is because what can deposited nearby the point souce is coral paniculate whichis not the most important of discharging. Business district is with higher mercury content while the industrial district not. Residential area is also exist peak value which need more attention. In the different districts of ChongQing downtown, the enrichment coefficient fall in this order:JiangBei district,YuZhong district, JiuLongpo district, DaDukou district, YuBei district,BeiBei district.The last part of this paper calculated the atmospheric mercury capacity to bel3.05t/a and the discharge amount allowed of lower pollution source is 1.96t/a (1.63 t/a for urban and 0.33 t/a for rural area). The limited amount of let-out of typical point souces was also estimated: 0.39 ton/y for ChongQing power plant and 0.50 ton/y for JiuLong power plant. The discharge amount now in fact is upper than the capacity, so need to be decreased. According to what we have known, some suggestion has been proposed:To set up inventory, to limit the discharge of major pollution sources, to push coal-washing and clean energy technology, to encourage fostering forests, to pay more attention to mercury pollution in soil and ph of soil, et al.
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