Disinfection byproducts in drinking water and regulatory compliance: A critical review

Disinfection by-products (DBPs) are regulated in drinking water in a number of countries. This critical review focuses on the issues associated with DBP regulatory compliance, including methods for DBP analysis, occurrence levels, the regulation comparison among various countries, DBP compliance strategies, and emerging DBPs. The regulation comparison between China and the United States (US) indicated that the DBP regulations in China are more stringent based on the number of regulated compounds and maximum levels. The comparison assessment using the Information Collection Rule (ICR) database indicated that the compliance rate of 500 large US water plants under the China regulations is much lower than that under the US regulations (e.g. 62.2% versus 89.6% for total trihalomethanes). Precursor removal and alternative disinfectants are common practices for DBP regulatory compliance. DBP removal after formation, including air stripping for trihalomethane removal and biodegradation for haloacetic acid removal, have gained more acceptance in DBP control. Formation of emerging DBPs, including iodinated DBPs and nitrogenous DBPs, is one of unintended consequences of precursor removal and alternative disinfection. At much lower levels than carbonaceous DBPs, however, emerging DBPs have posed higher health risks.     

Applications of nanomaterials in water treatment and environmental remediation

Nanotechnology has revolutionized plethora of scientific and technological fields; environmental safety is no exception. One of the most promising and well- developed environmental applications of nanotechnology has been in water remediation and treatment where different nanomaterials can help purify water through different mechanisms including adsorption of heavy metals and other pollutants, removal and inactivation of patho- gens and transformation of toxic materials into less toxic compounds. For this purpose, nanomaterials have been produced in different shapes, integrated into various composites and functionalized with active components. Nanomaterials have also been incorporated in nanostructured catalytic membranes which can in turn help enhance water treatment. In this article, we have provided a succinct review of the most common and popular nanomaterials （titania, carbon nanotubes （CNTs）, zero-valent iron, dendrimers and silver nanomaterials） which are currently used in environmental remediation and particularly in water purification. The catalytic properties and functionalities of the mentioned materials have also been discussed.     

高效液相色谱-质谱法测定土壤中溴代阻燃剂的方法

溴代阻燃剂种类较多,具有难降解性和生物蓄积性.目前,分析四溴双酚A和十溴联苯醚主要是采用GC-MS,这种方法灵敏度不高.六溴环十二烷受温度影响严重,易分解,不适于用GC-MS分析. 本实验用液相色谱-质谱进行分析,建立了一套简单灵敏的分析方法,并将其用于土壤样品的分析中.     

源头寻根

背包并不重,脚步踏着山路,阳光明媚,暖和地照着身体。穿过马岭桥,谷底幽深,令人有种畏惧的感觉。面对天下第一罗盘,双手合十虔诚地许下生日愿望,希望快乐到老,如此足矣。急不可待往珠江源头走。潺潺水流,从岩洞流出来的便是中国南方最富饶地区的水源,焉能想象?流水不紧不慢地淌着,与南方急速的节奏形成鲜明的对比。多美的风光,铺个防潮垫,发呆一会儿,躺着就睡起来。     

How aerosol direct effects influence the source contributions to PM2.5 concentrations over Southern Hebei,China in severe winter haze episodes

The aerosol direct effects result in a 3%–9% increase in PM_2.5 concentrations over Southern Hebei. These impacts are substantially different under different PM_2.5 loadings. Industrial and domestic contributions will be underestimated if ignoring the feedbacks. Beijing-Tianjin-Hebei area is the most air polluted region in China and the three neighborhood southern Hebei cities, Shijiazhuang, Xingtai, and Handan, are listed in the top ten polluted cities with severe PM_2.5 pollution. The objective of this paper is to evaluate the impacts of aerosol direct effects on air quality over the southern Hebei cities, as well as the impacts when considering those effects on source apportionment using three dimensional air quality models. The WRF/Chem model was applied over the East Asia and northern China at 36 and 12 km horizontal grid resolutions, respectively, for the period of January 2013, with two sets of simulations with or without aerosol-meteorology feedbacks. The source contributions of power plants, industrial, domestic, transportation, and agriculture are evaluated using the Brute-Force Method (BFM) under the two simulation configurations. Our results indicate that, although the increases in PM_2.5 concentrations due to those effects over the three southern Hebei cities are only 3%–9% on montly average, they are much more significant under high PM_2.5 loadings (~50 μg·m⁻³ when PM_2.5 concentrations are higher than 400 μg m⁻³). When considering the aerosol feedbacks, the contributions of industrial and domestic sources assessed using the BFM will obviously increase (e.g., from 30%–34% to 32%–37% for industrial), especially under high PM_2.5 loadings (e.g., from 36%–44% to 43%–47% for domestic when PM_2.5>400 μg·m⁻³). Our results imply that the aerosol direct effects should not be ignored during severe pollution episodes, especially in short-term source apportionment using the BFM.     

2，2‘,4,4’和3，3‘,4,4’—四氯联苯（TCB）对小白鼠体外受精的影响

采用体外受精技术评价环境污染物2，2',4,4'-和3，3',4,4'-四氯联苯对小白鼠卵母细胞受精能力和2-细胞胚胎发育的毒性作用，实验结果表明：ρ（PCB）=0.1,1.0,10.0mg/mL的2，2',4,4'-和3，3',4,4'-四氯联苯均显著降低小白鼠卵母细胞的受精能力；ρ（PCB）=1.0,10.0mg/mL的2，2',4,4'-和3，3',4,4'-四氯联苯使卵母细胞的退人弦和2-细胞的畸形率显著增加；两种四氯联苯对小白鼠卵母细胞体外受精能力、退化率和2-细胞胚胎的畸形率无统计差异。     

城市及其遗产:保存的根源和条件

城市遗产的保存和利用将都市管理的负责人置于艰难选择的境地.下面的文字对城市的构 成进行了简短的历史回顾，得出了在场所利用及其保存之间保持平衡发展条件.     

Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake, Lake Taihu, China

The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT_1.92 > DGT_0.78 > DGT_0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.