环境监测实验室空气中汞污染与防治

采用冷原子吸收法,使用便携式测汞仪对实验室空气中汞的浓度进行测定,监测结果表明,环境监测实验室空气中汞的污染较为严重,主要来源于COD、氨氮、大气中氨及汞样品测定时含汞试剂及汞标液的使用和含汞废液的排放。根据对监测结果的评价和分析提出了相应的防治措施,提醒实验室的管理及分析人员,要增强环境保护意识,加强实验室的管理,减少含汞及其它有毒废液的排放,改善实验室的环境空气质量,保护分析人员的身体健康。     

汞分析仪直接测定土壤中总汞的方法研究

建立了利用RP91C-RA915M汞分析仪直接测定土壤中总汞的方法。该方法直接固体进样,省去了常规方法加酸消解、赶酸、定容等繁琐的前处理步骤;利用标准土壤绘制工作曲线,无需反复稀释标准储备液配制标准溶液,测定了方法检出限、精密度及准确度。结果表明此方法准确、可靠,是一个比较理想的分析方法。本方法的检出限为0.25μg/kg,相对标准偏差为1.98%~4.92%,标准样品测定准确,加标回收率为92.8%~106%。     

Hg0 removal from flue gas over different zeolites modified by FeCl3

The elemental mercury removal abilities of three different zeolites (NaA, NaX, HZSM-5) impregnated with iron (III) chloride were studied on alab-scale fixed-bed reactor. X-ray diffraction, nitrogen adsorption porosimetry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and temperature programmed desorption (TPD) analy-ses were used to investigate the physicochemical properties. Results indicated that the pore structure and active chloride species on the surface of the samples are the key factors for physisorption and oxidation of Hg⁰, respectively. Relatively high surface area and micropore volume are beneficial to efficient mercury adsorption. The active Cl species generated on the surface of the samples were effective oxidants able to convert elemental mercury (Hg⁰) into oxidized mercury (Hg²⁺). The crystallization of NaCl due to the ion exchange effect during the impregnation of NaA and NaX reduced the number of active Cl species on the surface, and restricted the physisorption of Hg⁰. Therefore, the Hg⁰ removal efficiencies of the samples were inhibited. The TPD analysis revealed that the species of mercury on the surface of FeCl₃-HZSM-5 was mainly in the form of mercuric chloride(HgCl₂), while on FeCl₃-NaX and FeCl₃-NaA it was mainly mercuri coxide(HgO).     

Consumption of rice and fish in an electronic waste recycling area contributes significantly to total daily intake of mercury

<正>Mercury is a global pollutant due to its widespread use,emission,and long-range transport(Blum,2013;Pacyna et al.,2010).It is considered a priority pollutant due to its neurological toxicity,persistence,and bioaccumulation(Pacyna et al.,2010;Sharma et al.,2015).Mercury pollution can occur when products that contain mercury are improperly disposed of and mercury is released into the air,water,and soil(Zhang and Wong,2007).An estimated 22%of the annual world usage of mercury is in electrical equipment such as batteries,thermometers,and discharge lamps,and electronic devices such as monitors and     

Responses of soil ammonia oxidizers to a short-term severe mercury stress

The responses of soil ammonia-oxidizing archaea(AOA) and ammonia-oxidizing bacteria(AOB) to mercury(Hg) stress were investigated through a short-term incubation experiment.Treated with four different concentrations of Hg(CK,Hg25,Hg50,and Hg100,denoting 0,25,50,and 100 mg Hg/kg dry soil,respectively),samples were harvested after 3,7,and 28 day incubation.Results showed that the soil potential nitrification rate(PNR) was significantly inhibited by Hg stress during the incubation.However,lower abundances of AOA(the highest in CK: 9.20 × 10~7 copies/g dry soil; the lowest in Hg50: 2.68 × 10~7 copies/g dry soil) and AOB(the highest in CK: 2.68 × 10~7 copies/g dry soil; the lowest in Hg50:7.49 × 10~6 copies/g dry soil) were observed only at day 28 of incubation(P 0.05).Moreover,only the community structure of soil AOB obviously shifted under Hg stress as seen through DGGE profiles,which revealed that 2–3 distinct AOB bands emerged in the Hg treatments at day 28.In summary,soil PNR might be a very useful parameter to assess acute Hg stress on soil ecosystems,and the community structure of soil AOB might be a realistic biological indicator for the assessment of heavy metal stress on soil ecosystems in the future.     

Mercury levels and estimated total daily intakes for children and adults from an electronic waste recycling area in Taizhou, China: Key role of rice and fish consumption

In order to assess the potential health risks of Hg pollution, total mercury (T–Hg) and methyl mercury (MeHg) concentrations were determined in air, dust, surface soil, crops, poultry, fish and human hair samples from an electronic waste (e-waste) recycling area in Taizhou, China. High concentrations of T–Hg and MeHg were found in these multiple matrices, and the mean concentration was 30.7 ng/m³ of T–Hg for atmosphere samples, 3.1 μg/g of T–Hg for soil, 37.6 μg/g of T–Hg for dust, 20.3 ng/g of MeHg for rice and 178.1 ng/g of MeHg for fish, suggesting that the e-waste recycling facility was a significant source of Hg. The inorganic Hg (I–Hg) levels (0.84 μg/g) in hair samples of e-waste workers were much higher than that in the reference samples. Pearson''s correlation coefficients showed that strong positive correlations (p < 0.01) between hair I–Hg and time staying in industrial area (r = 0.81) and between MeHg and fish consumption frequency (r = 0.91), imply that workers were mainly exposed to Hg vapor through long-time inhalation of contaminated air and dust, while other population mainly exposed to MeHg through high-frequency fish consumption. The estimated daily intakes of Hg showed that dietary intake was the major Hg exposure source, and Hg intakes from rice and fish were significantly higher than from any other foods. The estimated total daily intakes (TDIs) of MeHg for both children (696.8 ng/(kg·day)) and adults (381.3 ng/(kg·day)) greatly exceeded the dietary reference dose (RfD) of 230 ng/(kg·day), implying greater health risk for humans from Hg exposures around e-waste recycling facilities.     

Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor

In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl₂, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr₂ and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr₂ and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.     

Predicted no-effect concentrations for mercury species and ecological risk assessment for mercury pollution in aquatic environment

Mercury(Hg) exists in different chemical forms presenting varied toxic potentials. It is necessary to explore an ecological risk assessment method for different mercury species in aquatic environment. The predicted no-effect concentrations(PNECs) for Hg(Ⅱ) and methyl mercury(Me Hg) in the aqueous phase, calculated using the species sensitivity distribution method and the assessment factor method, were 0.39 and 6.5 × 10-3μg/L, respectively. The partition theory of Hg between sediment and aqueous phases was considered, along with PNECs for the aqueous phase to conduct an ecological risk assessment for Hg in the sediment phase. Two case studies, one in China and one in the Western Black Sea, were conducted using these PNECs. The toxicity of mercury is heavily dependent on their forms,and their potential ecological risk should be respectively evaluated on the basis of mercury species.     

典型钢铁企业汞排放水平及排放特征研究

以某典型钢铁企业为研究对象,测定企业废气、废水、固废汞排放水平,并分析汞排放特征。研究表明,球团、烧结、高炉工艺废气排口烟尘中汞排放浓度和排放速率明显低于烟气;汞主要以气态形式排放,烧结工艺排口废气汞最高浓度分别是其他2个排口的7倍和3倍。球团、烧结、高炉、电炉四工艺环节中,烧结汞排放速率占四工艺汞排放速率总和的87%。半干法脱硫、氨法脱硫、石灰石石膏脱硫对废气中汞的去除效率分别为90.0%、78.7%和29.9%。企业废水排放未检出汞,脱硫产生固废汞含量明显高于除尘产生固废汞含量,脱硫灰汞含量是脱硫石膏的15倍。     

Linking landscape development intensity within watersheds to methyl-mercury accumulation in river sediments

An indicator of the disturbance of natural systems, the landscape development intensity (LDI) index, was used to assess the potential for land-use within watersheds to influence the production/accumulation of methyl-mercury (MeHg) in river sediments. Sediment samples were collected from locations impacted by well-identified land-use types within the Mobile-Alabama River Basin in Southeastern USA. The samples were analyzed for total-Hg (THg) and MeHg concentrations and the obtained values correlated to the calculated LDI indexes of the sampled watersheds to assess the impact of prevalent land use/land cover on MeHg accumulation in sediments. The results show that unlike THg, levels of MeHg found in sediments are impacted by the LDI indexes. Overall, certain combinations of land-use types within a given watershed appear to be more conducive to MeHg accumulation than others, therefore, pointing to the possibility of targeting land-use practices as potential means for reducing MeHg accumulation in sediments, and ultimately, fish contamination.