Combined use of DGT and transplanted shrimp (Litopenaeus vannamei) to assess the bioavailable metals of complex contamination: implications for implementing bioavailability-based water quality criteria

The diffusive gradients in thin films (DGT) were field deployed alongside the shrimp Litopenaeus vannamei at seven sites with different levels of contamination to assess the potentially bioavailable and toxic fraction of metal contaminants. After 7 days of exposure, several antioxidant biomarkers were quantified in hepatopancreas of exposed shrimps, and tissue levels as well as the total, dissolved, and DGT-labile concentrations of metal contaminants were determined in the pooled site samples. The results showed that the caged shrimps had high tissue contaminant concentrations and significantly inhibited antioxidant responses at the more contaminated sites. DGT-labile metal concentrations provided better spatial resolution of differences in metal contamination when compared with traditional bottle sampling and transplanted shrimp. The total, dissolved, and DGT-labile metal fractions were used to evaluate the potential bioavailability of metal contaminants, comparing with metal accumulation and further linking to antioxidant biomarker responses in tissues of exposed shrimps. Regression analysis showed the significant correlations between DGT-Cu concentrations and tissue-Cu and activities of some biomarker responses in the shrimp hepatopancreas. This indicated that DGT-labile Cu concentrations provided the better prediction of produced biological effects and of the bioavailability than the total or dissolved concentrations. The study supports the use of methods combining transplanted organisms and passive sampling for assessing the chemical and ecotoxicological status of aqueous environments and demonstrates the capability of the DGT technique as a powerful tool for measuring the bioavailability-based water quality in variable coastal environments.     

Quantitative modelling to estimate the transfer of pharmaceuticals through the food production system

Use of pharmaceuticals in animal production may cause an indirect route of contamination of food products of animal origin. This study aimed to assess, through mathematical modelling, the transfer of pharmaceuticals from contaminated soil, through plant uptake, into the dairy food production chain. The scenarios, model parameters, and values refer to contaminants in emission slurry production, storage time, immission into soil, plant uptake, bioaccumulation in the animal's body, and transfer to meat and milk. Modelling results confirm the possibility of contamination of dairy cow's meat and milk due the ingestion of contaminated feed by the cattle. The estimated concentration of pharmaceutical residues obtained for meat ranged from 0 to 6 ng kg^?1 for oxytetracycline, from 0.011 to 0.181 μg kg^?1 for sulfamethoxazole, and from 4.70 to 11.86 μg kg^?1 for ketoconazole. The estimated concentrations for milk were: zero for oxytetracycline, lower than 40 ng L^?1 for sulfamethoxazole, and from 0.98 to 2.48 μg L^?1 for ketoconazole. Results obtained for the three selected pharmaceuticals indicate a minor risk for human health. This study showed that supply chain modelling could be an effective tool in assessing the indirect contamination of feedstuff and animal products by residues of pharmaceuticals. The model can easily be adjusted to other contaminants and supply chain and, in this way, present a valuable tool to underpin decision making.     

Environmental impact assessment of infrastructure projects: a governance perspective

Environmental impact assessment (EIA) has been promoted as an instrument for preventive environmental management in construction projects, but its performance in safeguarding the environment through influencing project decision-making is questioned. This paper probes the underlying reasons from a governance perspective as an important supplement to the regulatory and technical perspectives. A framework, with process integration, professional governance, and public engagement being its key components, is proposed to analyze the governance arrangements that enable or inhibit the effective functioning of EIA, based on which a comparative study of three infrastructure projects in China, the United States and Finland was conducted. The results reveal that, while the level of process integration and public engagement of EIA determines the degree to which EIA influences project decisions, it is the professional governance that controls the accountability of EIA. The paper has implications on institutionally where efforts should be directed to improve the performance of EIA.     

Impacts of climatic and atmospheric changes on carbon dynamics in the Great Smoky Mountains National Park

We used the Dynamic Land Ecosystem Model (DLEM) to estimate carbon (C) storage and to analyze the impacts of environmental changes on C dynamics from 1971 to 2001 in Great Smoky Mountain National Park (GRSM). Our simulation results indicate that forests in GRSM have a C density as high as 15.9kgm(-2), about twice the regional average. Total carbon storage in GRSM in 2001 was 62.2Tg (T=10(12)), 54% of which was in vegetation, the rest in the soil detritus pool. Higher precipitation and lower temperatures in the higher elevation forests result in larger total C pool sizes than in forests at lower elevations. During the study period, the CO(2) fertilization effect dominated ozone and climatic stresses (temperature and precipitation), and the combination of these multiple factors resulted in net accumulation of 0.9Tg C in this ecosystem.     

Sedimentation and seasonal variation of hexachlorocyclohexanes in sediments in a eutrophic lake, China

Hexachlorocyclohexane (HCH) concentrations in sediments and sediment trap fluxes of particulate organic carbon and HCHs were measured bi-weekly from March 31 to October 18, 2006 in an urban eutrophic lake in Tianjin, China, in order to investigate sedimentation and seasonal variation of HCHs in sediments. HCH concentrations (dry weight basis) ranged from 2.2 to 20.2 ng/g (mean 7.7 ng/g) in surface sediments and from 26.6 to 972.7 ng/g (mean 187.0 ng/g) in settling particles, respectively. A clear seasonal variation in HCH sedimentation and HCH concentrations in sediments was observed. The maximal HCH deposition occurred following a spring phytoplankton bloom. The average flux of HCHs to sediment was approximately 21-fold higher in April to mid-June as compared to late June to October. This was attributed to the high vertical fluxes at the end of the spring phytoplankton bloom. The maximum values of HCH concentrations in sediments were observed in mid-June to late July. Concentrations of HCHs in sediments from the eutrophic lake were well-correlated with organic carbon contents in sediments. The annual sediment trap flux of HCHs in the eutrophic lake, which was estimated using data obtained in the eutrophic lake, was 117 microg/m2 yr, about 72% of which was attributed to the sedimentation corresponding to spring bloom phytoplankton deposition in late May to mid-June. The high sediment trap flux of HCHs in the eutrophic lake was related to serious local contamination.     

叠层生态滤床技术在生活污水处理中的应用研究

针对农村生活污水的特点,设计叠层生态滤床,并将其应用于浙西山区农村生活污水的处理。运行结果表明,系统出水的COD、氨氮、总氮、总磷质量浓度分别为18.20、0.492、0.77、0.129 mg/L,去除率分别达到43.30%、56.42%、42.11%、19.88%,出水的COD、氨氮、总氮、总磷均满足《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准。叠层生态滤床处理农村生活污水的吨水投资成本较低,后期运行基本不产生费用,而且在后期管理上不需要配备专门的技术人员,适用于不同经济发展程度农村的生活污水处理,具有良好的推广价值。     

Trace element changes in soil after long-term cattle manure applications

Manure application supplies plant nutrients, but also leads to trace element accumulation in soil. This study investigated total and EDTA-extractable B, Cd, Co, Cu and Zn in soil after 25 annual manure applications. The residual effect of 14 annual manure applications followed by 11 yr with no applications was also investigated. Manure was applied at 0, 30, 60 and 90 Mg ha(-1) yr(-1) (wet weight) under rainfed (treatments Mr0, Mr30, Mr60, and Mr90) and at 0, 60, 120 and 180 Mg ha(-1) yr(-1) under irrigated conditions (Mi0, Mi60, Mi120, and Mi180). The manure applications had no significant effect on soil B, Cd and Co content under both rainfed and irrigated conditions, but significantly increased total Cu and Zn content under irrigated conditions with Zn in Mi120 and Mi180 reaching the lower maximum concentration (MAC) level set by the European Community. Manure application also significantly increased EDTA-extractable Cd and Zn content in soil. Up to 27% of the total Cd (0.156 mg kg(-1)) and 21% of total Zn (38 mg kg(-1)) are found in EDTA-extractable form (Mi180 at 0-15 cm). EDTA-extractable Cd and Zn content was also significantly elevated in the irrigated residual plots due to the higher manure rates used. Thus, the impacts of cattle manure application on trace elements in soil are long lasting. Elevated Cd and Zn are a concern as other studies have linked them with certain types of cancers and human illnesses.     

巢湖迎风面直立堤岸生态修复技术研究

针对巢湖直立堤岸生态系统受损的现状,研发了适合于巢湖迎风面的直立堤岸基底改善与生态修复技术。考虑到直立堤岸迎风面风浪较大且淘蚀严重的特点,首先对传统的生态混凝土配方进行改良,从而较大程度地提高了生态混凝土的物化性能,使其具备高透水性、高稳固性、植生性等诸多优点。同时,以巢湖湖滨带现场调查与野外模拟实验结果为依据,确定巢湖湖滨带最适的基底类型为灰壤（植入深度10 cm）,并适当添加铁盐和铝盐;确定最适的植被类型为飞蓬草。在此基础上,确定生态混凝土最适配比为江砂〖DK〗∶碎石〖DK〗∶水泥=10〖DK〗∶3〖DK〗∶2,进而集成研发了生态混凝土 原位土壤 植被混合护坡技术。该技术应用到迎风面的直立堤岸后,植被覆盖率超过70%,土壤中有效磷削减67%以上     

主压缩沉降阶段垃圾填埋体渗透特性研究

针对垃圾填埋体的研究主要集中在降解及垃圾渗滤液处理,而其渗透特性研究不足的现状,选取处于4种压力状况下的垃圾填埋体,对其主压缩沉降阶段渗透特性进行室内物理试验,结合试验数据对垃圾填埋体渗透性能变化规律进行分析研究.结果表明,4种压力状况下垃圾填埋体试验测定分析符合达西定律,其COD变化处于产酸阶段,对渗透性能的影响可以不予考虑;在此基础上,对垃圾渗透系数计算表明,处于主压缩沉降阶段内,除没有施加压力状况下垃圾填埋体渗透性能变化规律与其他试验表现不尽相同外,其他垃圾填埋体渗透系数变化大致符合自然指数规律,而4种压力状态下的垃圾填埋体渗透系数数值均在10~(-4.5)～10~(-5.3) m·s~(-1)的范围内,与典型垃圾渗透系数的代表值相一致.     

不同表面状态对6061铝合金耐蚀性能的影响研究

目的研究在温度和表面粗糙度不同的情况下,6061铝合金的耐蚀性能变化,并研究表面硫酸、硼酸硫酸阳极氧化对提高6061铝合金耐蚀性能的作用。方法对试样进行中性盐雾试验和电化学实验。结果随着表面粗糙度的下降,6061铝合金的耐蚀性有所提高,且表面经过阳极氧化后,试样表面盐粒沉积量大幅下降,腐蚀面积有所减少。随着温度升高,6061铝合金的耐蚀性下降,而当温度达到55℃时,试样表面出现了一定的钝化现象,当温度继续升高,钝化现象消失,腐蚀速率重新上升。结论随温度和表面粗糙度的提高,6061铝合金的耐蚀性能下降,而55℃为6061铝合金较好的钝化温度。