Assessment of soil lead exposure in children in Shenyang, China

Soil lead pollution is serious in Shenyang, China. The paper brings together the soil work, the bioaccessibility, and the blood lead data to assess the soil lead exposure in children in Shenyang, China. Approximately 15.25% of the samples were above China Environment Protection Agency guideline concentration for soil Pb to protect human from health risk (350 mgkg(-1)). Pb concentrations varied among use scenarios. The main lead contamination sources are industry emission and automobile exhaust. Bioaccessibility also varied among use scenarios. Children, who ingested soil from industrial area, public parks, kindergarten playground, and commercial area, are more susceptible to soil lead toxicity. The industrial area soil samples presented higher bioaccessibility compared to the other use scenario soil samples contaminated by automobile exhaust. The result also suggested a most significant linear relationship between the level of Pb contamination and the amount of Pb mobilized from soil into ingestion juice. Soil pH seemed to have insignificant influence on bioaccessibility in the present study. Bioaccessibility was mainly controlled by other factors that are not investigated in this study. A linear relationship between children blood lead and soil intestinal bioaccessibility was present in the study. Children who are 4-5 years old are more likely to demonstrate the significant relationship between soil lead bioaccessibility and blood lead as their behaviors place them at greatest risk of soil lead toxicity, and their blood lead levels are more likely to represent recent exposure.     

Variations of bacterial community structure in flooded paddy soil contaminated with herbicide quinclorac

The denaturing gradient gel electrophoresis (DGGE) method was applied to determine the relative genetic complexity of microbial communities in flooded paddy soil treated with herbicide quinclorac (3,7-dichloro-8-quinoline-carboylic acid). The results obtained showed a significant effect of quinclorac on the development of bacterial populations in soils contaminated with different concentrations of the herbicide at the early time after application. In general, however, the number of populations of the same soil sample treated with the same concentration of the quinclorac differed obviously with increasing incubation time within the early 8 weeks. The scale of differences in banding patterns-showed that the microbial community structures of the quinclorac-treated and non-quinclorac-treated soils were not significantly different after 21 weeks of incubation. Quantification, as demonstrated in this paper, was studied by establishing dose-response relationships. Significant pattern variations were quantified. Prominent DGGE bands were excised, cloned and sequenced to gain insight into the identities of predominant bacterial populations. The majority of DGGE band sequences were related to bacterial genera Clostridium, Sphingobacterium, Xanthomonas and Rhodococcus.     

Probabilistic study of well capture zones distribution at the Lauswiesen field site

The delineation of well capture zones is of utmost environmental and engineering relevance as pumping wells are commonly used both for drinking water supply needs, where protection zones have to be defined, and for investigation and remediation of contaminated aquifers. We analyze the probabilistic nature of well capture zones within the well field located at the "Lauswiesen" experimental site. The test site is part of an alluvial heterogeneous aquifer located in the Neckar river valley, close to the city of Tübingen in South-West Germany. We explore the effect of different conceptual models of the structure of aquifer heterogeneities on the delineation of three-dimensional probabilistic well catchment and time-related capture zones, in the presence of migration of conservative solutes. The aquifer is modeled as a three-dimensional, doubly stochastic composite medium, where distributions of geo-materials and hydraulic properties are uncertain. We study the relative importance of uncertain facies geometry and uncertain hydraulic conductivity and porosity on predictions of catchment and solute time of travel to the pumping well by focusing on cases in which (1) the facies distribution is random, but the hydraulic properties of each material are fixed, and (2) both facies geometry and material properties vary stochastically. The problem is tackled within a conditional numerical Monte Carlo framework. Results are provided in terms of probabilistic demarcations of the three-dimensional well catchment and time-related capture zones. Our findings suggest that the uncertainty associated with the prediction of the location of the outer boundary of well catchment at the "Lauswiesen" site is significantly affected by the conceptual model adopted to incorporate the heterogeneous nature of the aquifer domain in a predictive framework. Taking into account randomness of both lithofacies distribution and materials hydraulic conductivity allows recognizing the existence of preferential flow paths that influence the extent of the well catchment and the solute travel time distribution at the site.     

Effects of ultraviolet radiation and contaminant-related stressors on arctic freshwater ecosystems

Climate change is likely to act as a multiple stressor, leading to cumulative and/or synergistic impacts on aquatic systems. Projected increases in temperature and corresponding alterations in precipitation regimes will enhance contaminant influxes to aquatic systems, and independently increase the susceptibility of aquatic organisms to contaminant exposure and effects. The consequences for the biota will in most cases be additive (cumulative) and multiplicative (synergistic). The overall result will be higher contaminant loads and biomagnification in aquatic ecosystems. Changes in stratospheric ozone and corresponding ultraviolet radiation regimes are also expected to produce cumulative and/or synergistic effects on aquatic ecosystem structure and function. Reduced ice cover is likely to have a much greater effect on underwater UV radiation exposure than the projected levels of stratospheric ozone depletion. A major increase in UV radiation levels will cause enhanced damage to organisms (biomolecular, cellular, and physiological damage, and alterations in species composition). Allocations of energy and resources by aquatic biota to UV radiation protection will increase, probably decreasing trophic-level productivity. Elemental fluxes will increase via photochemical pathways.     

Interaction effects of metals and salinity on biodegradation of a complex hydrocarbon waste

The presence of high levels of salts because of produced brine water disposal at flare pits and the presence of metals at sufficient concentrations to impact microbial activity are of concern to bioremediation of flare pit waste in the upstream oil and gas industry. Two slurry-phase biotreatment experiments based on three-level factorial statistical experimental design were conducted with a flare pit waste. The experiments separately studied the primary effect of cadmium [Cd(II)] and interaction effect between Cd(II) and salinity and the primary effect of zinc [Zn(II)] and interaction effect between Zn(II) and salinity on hydrocarbon biodegradation. The results showed 42-52.5% hydrocarbon removal in slurries spiked with Cd and 47-62.5% in the slurries spiked with Zn. The analysis of variance showed that the primary effects of Cd and Cd-salinity interaction were statistically significant on hydrocarbon degradation. The primary effects of Zn and the Zn-salinity interaction were statistically insignificant, whereas the quadratic effect of Zn was highly significant on hydrocarbon degradation. The study on effects of metallic chloro-complexes showed that the total aqueous concentration of Cd or Zn does not give a reliable indication of overall toxicity to the microbial activity in the presence of high salinity levels.     

苏北地区农业环境问题及管理方案的探讨

配合江苏省“碧海计划”和盐城市海洋经济绿色农业的发展，探讨了现阶段农业环境污染控制的直接政策管理、经济手段和人工生态工程处理三种方案，其中政策管理，如减少化肥农药的施用规定能减少污染，直接经济投入少，但是执行管理成本高，且政策见效慢；经济手段能减少污染，但环境目标达标不确定，且需要完善的市场环境，目前来说，本地区市场机制不完善，会出现“市场失灵”现象；人工湿地生态工程，前期投入大，但管理成本低，环境目标确定，但不能快速削减污染负荷。三种方案各有所长，在实际操作中，应针对不同区域的农业产业状况、方案时间迟度组合使用。     

四种净水工艺对水源水微量有机物去除的研究

以UV254和CODMn代表饮用水源水中有机物替代指标.对常规处理、生物陶粒预处理、生物滤池、生物活性炭(BAC)、颗粒活性炭(GAC)、纳滤和光催化氧化进行组合,形成不同的处理流程,研究各流程对UV254和CODMn的去除效果.结果表明,各工艺流程都有一定的处理效率,其中以生物滤池和纳滤为主的组合流程处理效果最佳.此流程对UV254的去除率接近100%,CODMn的去除率达到78.6%,大大提高了饮用水的安全性.     

三峡水库135 m蓄水前后水体重金属环境健康风险评价

三峡水库135 m蓄水后,水体中各重金属的单因子污染指数和Nemerow综合污染指数均有不同程度的增大,特别是Pb污染应该引起重视.健康风险评价结果表明,成库前后非致癌有毒化学物质(Hg、Pb和Cu)所引起的健康危害的个人年风险为Pb＞Cu＞Hg,致癌物质对人体健康危害的个人年风险均大于非致癌物.各类污染物所致个人平均健康危害成库前后均低于国际辐射防护委员会(ICRP)推荐的标准,为可接受水平.     

HCHs and DDTs in sediment-dwelling animals from the Yangtze Estuary, China

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2-5.5 ng g(-1) and averaged 3.5 ng g(-1) in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g(-1), with a mean of 34.5 ng g(-1). In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g(-1) and averaged 13.8 ng g(-1), whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g(-1) with a mean value of 5.9 ng g(-1). The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.     

Modelling the extra and intracellular uptake and discharge of heavy metals in Fontinalis antipyretica transplanted along a heavy metal and pH contamination gradient

Samples of the aquatic bryophyte Fontinalis antipyretica Hedw. were transplanted to different sites with the aim of characterizing the kinetics of the uptake and discharge of heavy metals in the extra and intracellular compartments. The accumulation of metals in extracellular compartments, characterized by an initial rapid accumulation, then a gradual slowing down over time, fitted perfectly to a Michaelis-Menten model. The discharge of metals from the same compartment followed an inverse linear model or an inverse Michaelis-Menten model, depending on the metal. In intracellular sites both uptake and discharge occurred more slowly and progressively, following a linear model. We also observed that the acidity of the environment greatly affected metal accumulation in extracellular sites, even when the metals were present at relatively high concentrations, whereas the uptake of metals within cells was much less affected by pH.