Environmental mercury contamination of an artisanal zinc smelting area in Weining County, Guizhou, China

To investigate the extent of Hg contamination due to artisanal Zn smelting activities in Weining County, northwestern Guizhou, China, total Hg and methyl mercury (MeHg) concentrations in soil and surface water were determined. Samples of corn plants growing in the study area were also collected for total Hg analysis. A high geometric mean Hg emission factor of 75gHgt(-1)Zn was estimated and significantly elevated total gaseous mercury (TGM) concentrations were found in the atmosphere adjacent to the Zn smelting sites, ranging from 30 to 3814ngm(-3). Total Hg and MeHg concentrations in topsoil samples ranged from 62 to 355microgkg(-1) and from 0.20 to 1.1microgkg(-1), respectively. Total Hg Concentrations in corn plant tissues increased in the order of grains相似文献   

曝气对电解除磷的影响研究

针对高浓度含磷废水,重点分析了电解除磷工艺中曝气对磷去除率、pH、电导率、电极钝化的影响.结果表明:(1)在电流密度为20 mA/cm2、磷初始质量浓度为200 mg/L,初始pH为5.5～6.5的条件下,当曝气量为1.0、1.5、2.0 L/min时,60 min内磷去除率均接近100%,而且出水中未检测出磷,符合<污水综合排放标准>(GB 8978-1996)中一级标准,30～40 min内,磷去除率达到了95%以上,磷残余质量浓度小于10 mg/L,相比未曝气的情况,磷去除率有了显著提高;(2)在电流密度为20 mA/cm2、磷初始质量浓度为200 mg/L、初始pH约为3的条件下,曝气溶液的pH在前30 min呈上升趋势.30 rain后趋于平缓,最终停留在8左右;(3)在电流密度为20 mA/cm2、磷初始质量浓度为200 mg/L、初始pH约为3的条件下,曝气溶液的电导率在整个电解除磷过程中先逐步下降,30～40 min后逐步趋于稳定;(4)曝气对于抑制电极钝化、提高磷去除率有着显著效果.     

Airborne trace element pollution in 11 European cities assessed by exposure of standardised ryegrass cultures

Within a European biomonitoring programme, Italian ryegrass (Lolium multiflorum Lam.) was employed as accumulative bioindicator of airborne trace elements (As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, V, Zn) in urban agglomerations. Applying a highly standardised method, grass cultures were exposed for consecutive periods of four weeks each to ambient air at up to 100 sites in 11 cities during 2000–2002. Results of the 2001 exposure experiments revealed a clear differentiation of trace element pollution within and among local monitoring networks. Pollution was influenced particularly by traffic emissions. Especially Sb, Pb, Cr, Fe, and Cu exhibited a very uneven distribution within the municipal areas with strong accumulation in plants from traffic-exposed sites in the city centres and close to major roads, and moderate to low levels in plants exposed at suburban or rural sites. Accumulation of Ni and V was influenced by other emission sources. The biomonitoring sites located in Spanish city centres featured a much higher pollution load by trace elements than those in other cities of the network, confirming previously reported findings obtained by chemical analyses of dust deposition and aerosols. At some heavily-trafficked sites, legal thresholds for Cu, Pb, and V contents in foodstuff and animal feed were reached or even surpassed. The study confirmed that the standardised grass exposure is a useful and reliable tool to monitor and to assess environmental levels of potentially toxic compounds of particulate matter.     

Study Progress and Trends of Strategic Environmental Assessment in China

Strategic environmental assessment （SEA） in China has developed rapidly since it was introduced into China in the 1990s. Chinese government promulgated the Environmental Impact Assessment Law of China （hereinafter referred to as the EIA Law） in 2002. In this law, it is stipulated clearly that regional and sector plans should be assessed. Through investigating materials and analyzing literatures, this article analyses the practical and academic study achievements of SEA in China that have been achieved since the EIA Law was implemented, probes into the current situation of the main level of SEA in China-plan EIA, then summarizes the development characteristics, and eventually, puts forward the development trends of SEA in China. The research conclusions can offer the foundations for comprehending systematically the progress of SEA in China.     

纳米铁去除水中硝酸盐的动力学研究

实验中采用了液相还原法制备新型吸附剂纳米铁。在纳米铁低投放量的条件下,采用间歇实验,分别从初始硝酸盐浓度、溶液pH值和温度的不同外界条件下研究了纳米铁对硝酸盐的去除情况。实验结果表明,硝酸盐初始浓度对反应速率有影响,但对去除率影响不大;溶液pH值为2.0时纳米铁对硝酸盐的去除效果最好;随着温度的升高,纳米铁对硝酸盐的去除率有所增加。以t时刻已反应掉的硝酸盐浓度为切入点,提出拟二级动力学方程。进而确定不同温度下的反应速率常数k。实验中k在50℃时最大,为0.014 mg/（L·min）。反应活化能Ea为17.18 kJ/mol,该反应以质量传递为控制因素。溶液中性条件下硝酸盐氮的还原产物为氨氮。     

A~2/O＋硫磺填料柱组合工艺脱氮除磷的效果

以某城市污水厂进水为研究对象,采用A2/O＋硫磺填料反应柱组合工艺,考察其对COD、总氮、总磷以及溶解性磷处理效果的改善。组合工艺出水水质稳定后,连续运行55 d,并对工艺的出水进行常规指标分析。结果表明：组合工艺的脱氮除磷效果较单个A2/O工艺都得到了较大的改善,而COD去除效果变化不大。A2/O系统对COD有良好的去除效果,出水的COD平均去除率能达到94%;TN和TP去除效果相对较差,出水平均去除率分别为60%和57.4%。经硫磺填料反应柱的脱氮除磷作用,系统出水TN去除率提高到84%,TP去除率提高到69.8%,COD去除率变化不大,升高到95.3%。     

一体式膜生物反应器处理生活污水的中试研究

采用中试规模(1.8 m3/d)的缺氧-好氧膜生物反应器(A/O MBR)对城市污水处理回用进行了试验研究.试验结果表明,该工艺处理效果优良,系统对COD、氨氮、浊度、总氮、总磷去除率较高,COD、氨氮出水浓度分别为7～39 mg/L、0～1.31 mg/L.出水水质优于城市杂用水水质标准(GB/T18920-2002).     

多级处理系统中的微生物生态结构和功能

对处理城市污水的多级生物系统工程研究表明,该系统为以细菌为主,包括真菌、酵母和藻类的复合生态系统,微生物类群随处理级数的增加而增多,菌数却随之减少,该系统中的微生物对油、酚有较强的降解力,对重金属有较高的抗性,采用新的硝化细菌综合毒性检测法检测出水水质表明,原污水的毒性降低78%。     

Effects of sludge dredging on the prevention and control of algae-caused black bloom in Taihu Lake, China

Algae-caused black bloom (also known as black water agglomerate) has recently become a critical problem in some Chinese lakes.It has been suggested that the occurrence of algae-caused black bloom was caused by the cooperation of nutrient-rich sediment with dead algae,and sludge dredging was adopted to control black bloom in some lakes of China.In this article,based on the simulation of black bloom using a Y-shape apparatus for modeling natural conditions,both un-dredged and dredged sites in three areas of Taihu Lake,China were studied to estimate the effects of dredging on the prevention and control of black bloom.During the experiment,drained algae were added to all six sites as an additional organic load;subsequently,the dissolved oxygen decreased rapidly,dropping to 0 mg/L at the sediment-water interface.Black bloom did not occur in the dredged sites of Moon Bay and Nan Quan,whereas all three un-dredged sites at Fudu Port,Moon Bay and Nan Quan experienced black bloom.Black bloom also occurred at the dredged site of Fudu Port one day later than at the other sites,and the odor and color were lighter than at the other locations.The color and odor of the black water mainly result from the presence of sulfides such as metal sulfides and hydrogen sulfide,among other chemicals,under reductive conditions.The color and odor of the water,together with the high concentrations of nutrients,were mainly caused by the decomposition of the algae and the presence of nutrient-rich sediment.Overall,the removal of the nutrient-rich sediment by dredging can prevent the occurrence and control the degree of algae-caused black bloom in Taihu Lake.     

Effects of physical and chemical characteristics of surface sediments in the formation of shallow lake algae-induced black bloom

In page 2357 of the published paper(Shen Q S, et al. Effects of physical and chemical characteristics of surface sediments in the formation of shallow lake algae-induced black bloom. Journal of Environmental Sciences, 2013, 25(12): 2353-2360), the units of the Fe²⁺ and Oxal-Fe²⁺ in Fig. 3(a) and Fig. 5 should be "mg/g" rather than "mg/kg".