Pollution, fractionation, and mobility of Pb, Cd, Cu, and Zn in garden and paddy soils from a Pb/Zn mining area.

This study was conducted to investigate the pollution load index, fraction distributions, and mobility of Pb, Cd, Cu, and Zn in garden and paddy soils collected from a Pb/Zn mine in Chenzhou City, China. The samples were analyzed using Leleyter and Probst's sequential extraction procedures. Total metal concentrations including Pb, Cd, Cu, and Zn exceeded the maximum permissible limits for soils set by the Ministry of Environmental Protection of China, and the order of the pollution index was Cd > Zn > Pb > Cu, indicating that the soils from both sites seriously suffered from heavy metal pollution, especially Cd. The sums of metal fractions were in agreement with the total contents of heavy metals. However, there were significant differences in fraction distributions of heavy metals in garden and paddy soils. The residual fractions of heavy metals were the predominant form with 43.0% for Pb, 32.3% for Cd, 33.5% for Cu, and 44.2% for Zn in garden soil, while 51.6% for Pb, 40.4% for Cd, 40.3% for Cu, and 40.9% for Zn in paddy soil. Furthermore, the proportions of water-soluble and exchangeable fractions extracted by the selected analytical methods were the lowest among all fractions. On the basis of the speciation of heavy metals, the mobility factor values of heavy metals have the following order: Cd (25.2-19.8%) > Cu (22.6-6.3%) > Zn (9.6-6.0%) > Pb (6.7-2.5%) in both contaminated soils.

[Transfer and Fate of Polybrominated Diphenyl Ethers in an Electrical Equipment Dismantling Area Using a Multimedia Fugacity Model].

The multimedia fugacity model (Ⅲ) was used to simulate the distribution, transfer and fate of typical polybrominated diphenyl ethers (PBDEs) in air, water, soil and sediment in an electrical equipment dismantling area in eastern China. The modeling data were compared with monitored values in air, soil and sediment for validation purpose. Moreover, the transfer fluxes between different compartments were analyzed in order to infer the main transfer process. Parameters of the model were tested and the key parameters were identified using sensitivity analysis method for BDE47 and BDE209.The results of sensitivity analysis indicated that vapor pressure, the lgKow value and half-life had significant influence on concentrations of PBDEs in different media. The results showed that when the system reached equilibrium, most of the PBDEs would be accumulated in soil and sediment. The air advection outflow and soil degradation were the major routes for PBDEs to disappear in the area. The results will provide the basis for the risk management of PBDEs contamination.

[Open-top Chamber for in situ Research on Response of Mercury Enrichment in Rice to the Rising Gaseous Elemental Mercury in the Atmosphere].

In situ research was conducted on the response of mercury enrichment in rice organs to elevated gaseous elemental mercury (GEM) with open-top chambers (OTCs) fumigation experiment and soil Hg enriched experiment. The results showed that Hg concentrations in roots were generally correlated with soil Hg concentrations (R = 0.9988, P < 0.05) but insignificantly correlated with air Hg concentrations (P > 0.05), indicating that Hg in rice roots was mainly from soil. Hg concentrations in stems increased linearly (R(B) = 0.9646, R(U) = 0.9831, P < 0.05) with elevated GEM, and Hg concentrations in upper stems were usually higher than those in bottom stems in OTCs experiment. Hg concentrations in bottom stems were generally correlated with soil Hg concentrations (R = 0.9901, P < 0.05) and second-order polynomial (R = 0.9989, P < 0.05) was fitted for Hg concentrations in upper stems to soil Hg concentrations, and Hg concentrations in bottom stems were usually higher than those in upper stems in soil Hg enriched experiment, indicating the combining impact of Hg from air and soil on the accumulation of mercury in stems. Hg concentrations in foliage were significantly correlated (P < 0.05) with air Hg and linearly correlated with soil Hg (R = 0.9983, P = 0.0585), implying that mercury in foliage was mainly from air and some of Hg in root from soil was transferred to foliage through stem. Based on the function in these filed experiments, it was estimated that at least 60%-94% and 56%-77% of mercury in foliage and upper-stem of rice was from the atmosphere respectively, and yet only 8%-56% of mercury in bottom-stem was attributed to air. Therefore, mercury in rice aboveground biomass was mainly from the atmosphere, and these results will provide theoretical basis for the regional atmospheric mercury budgets and the model of mercury cycling.

[Spatial distribution and evaluation of nitrogen, phosphorus and organic matter in surface sediments from western lakeside belt of Lake Taihu].

The surface sediments in western lakeside belt of Taihu Lake were collected. The spatial distribution of nutrients and pollution evaluation were studied. The results showed that concentration of the nitrogen, phosphorus and organic matter in the surface sediments had an increasing tendency from inshore to the far shore. The concentration of organic matter in the sediments ranged from 2261.78 mg x kg(-1) to 11963.10 mg x kg(-1), with the average of 7 124.00 mg x kg(-1). Total nitrogen concentration in the sediments ranged from 343.20 mg x kg(-1) to 1 390.12 mg x kg(-1), with the average of 819.20 mg x kg(-1). The total phosphorus concentration in the sediments ranged from 197.46 mg x kg(-1) to 570.85 mg x kg(-1), with the average of 379.39 mg x kg(-1). The C/N ratio in the lake sediment was 9.5. Organic matter and nutrient were from alga and aquatic plant in lake. Based on the organic index and organic nitrogen, we can concluded that the surface sediments in western lakeside belt of Taihu Lake still belong to less clean category. The average values of organic index and organic nitrogen were 0.037% and 0.044%, respectively. The organic index and organic nitrogen in offshore were high, which indicated the risk of organic pollution.