Direct comparison of 210Po, 234Th and POC particle-size distributions and export fluxes at the Bermuda Atlantic Time-series Study (BATS) site

Particle-reactive, naturally occurring radionuclides are useful tracers of the sinking flux of organic matter from the surface to the deep ocean. Since the Joint Global Ocean Flux Study (JGOFS) began in 1987, the disequilibrium between ²³⁴Th and its parent ²³⁸U has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, ²¹⁰Po and ²¹⁰Pb, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the ²¹⁰Po/²¹⁰Pb radiochemical balance in the ocean and because of the more time-consuming radiochemical procedures. Direct comparison of particle flux estimated in different ocean regions using these short-lived radionuclides is important in evaluating their utility and accuracy as tracers of particle flux. In this paper, we present paired ²³⁴Th/²³⁸U and ²¹⁰Po/²¹⁰Pb data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated ²¹⁰Po and ²³⁴Th activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both ²¹⁰Po and ²³⁴Th reasonably predict sinking POC flux caught in sediment traps, and each tracer provides unique information about the magnitude and efficiency of the ocean's biological pump.     

德国污水处理考虑减排的工程实例及思考

探讨污水处理系统脱氮和污泥消化中的减排潜力,即开发污泥碳源和能源。本文所列举的德国工程实例说明污泥裂解技术可以大幅改善污水处理系统的碳排放特性,并且通过污泥厌氧消化实现能源自给。     

Persistence of two neonicotinoid insecticides in wastewater, and in aqueous solutions of surfactants and dissolved organic matter

Wastewater treatment plants receive organic contaminants, such as pesticides, which reach the sewage system from domestic, industrial or agricultural activities. In wastewater, which is a complex mixture of organic and inorganic compounds, biotic or abiotic degradation of contaminants can be affected by the presence of co-solutes. The photodecomposition in natural sunlight of two neonicotinoid insecticides, thiamethoxam and thiacloprid, was investigated in wastewater, aqueous extracts of sewage sludge and in aqueous surfactant solutions, which are abundant in wastewater. Dissipation in the dark was also studied in wastewater, due to reduction of transmitted sunlight in wastewater ponds. With regard to photolysis, thiamethoxam degraded rapidly in all the aqueous solutions. Among them sewage sludge extracts slightly modified (average half-life 17.6 h), wastewater increased (13.7 h) and non-ionic surfactants led, as a family, to the highest dissipation rates (average 6.2 h), with respect to control water (18.7 h). Additionally this pesticide also underwent a slower biodegradation process in wastewater in the dark under anaerobic conditions (around 25 d). A metabolite of thiamethoxam from the biological decomposition in wastewater was identified by HPLC/MS. On the other hand thiacloprid was found to be resistant to photo- and biodecomposition and remained almost unchanged during the experimental periods in all the tested media.     

Oxidative stress, cytoxicity, and cell mortality induced by nano-sized lead in aqueous suspensions

This paper reports on the effect of aqueous and nano-particulated Pb on oxidative stress (lipid peroxidation), cytoxicity, and cell mortality. As determined by the Thiobarbituric Acid Reactive Substances (TBARS) method, only 6 h after incubation aqueous suspensions bearing nano-sized PbO₂, soluble Pb(II), and brain-homogenate only suspensions, were determined to contain as much as ca. 7, 5, and 1 nmol TBARS mg protein⁻¹, respectively. Exposure of human cells (central nervous system, prostate, leukemia, colon, breast, lung cells) to nano-PbO₂ led to cell-growth inhibition values (%) ca. ≤18.7%. Finally, as estimated by the Artemia salina test, cell mortality values were found to show high-survival larvae rates. Microscopic observations revealed that Pb particles were swallowed, but caused no mortality, however.     

Planting woody crops on dredged contaminated sediment provides both positive and negative effects in terms of remediation

There is currently a requirement for studies focusing on the long-term sustainability of phytoremediation technologies. Trace element uptake by Salix, Populus and Alnus species planted in dredged contaminated canal sediment and concentrations in sediment and pore waters were investigated, eight years after a phytoremediation trial was initiated in NW England. Soil biological activity was also measured using invertebrate and microbial assays to determine soil quality improvements. Zinc was the dominant trace metal in foliage and woody stems, and the most mobile trace element in sediment pore water (∼14 mg l⁻¹). Biological activity had improved; earthworm numbers had increased from 5 to 24, and the QBS index (an index of microarthropod groups in soil) had increased from 70 to 88. It is concluded that biological conditions had improved and natural processes appear to be enhancing soil quality, but there remains a potential risk of trace element transfer to the wider environment.     

Decrease in catalase activity of Folsomia candida fed a Bt rice diet

Here we report the effects of three Bt-rice varieties and their non-Bt conventional isolines on biological traits including survival, reproduction, and the activities of three antioxidant enzymes superoxide dismutase, catalase and peroxidase, in the Collembolan, Folsomia candida. The reproduction was significantly lower when fed Kemingdao and Huahui1 than those feeding on their non-GM near-isogenic varieties Xiushui and Minghui63 respectively, this can be explained by the differences of plant compositions depended on variety of rice. The catalase activity of F. candida was significantly lower when fed the Bt-rice variety Kemingdao compared to the near-isogenic non-Bt-rice variety Xiushui. This suggests that some Bt-rice varieties may impose environmental stress to collembolans. We emphasize that changes in activity of antioxidant enzymes of non-target organisms are important in understanding the ecological consequences for organisms inhabiting transgenic Bt-rice plantations.     

Chlorpyrifos degradation in a biomixture of biobed at different maturity stages

The biomixture is a principal element controlling the degradation efficacy of the biobed. The maturity of the biomixture used in the biobed affects its overall performance of the biobed, but this is not well studied yet. The aim of this research was to evaluate the effect of using a typical composition of Swedish biomixture at different maturity stages on the degradation of chlorpyrifos. Tests were made using biomixture at three maturity stages: 0 d (BC0), 15 d (BC15) and 30 d (BC30); chlorpyrifos was added to the biobeds at final concentration of 200, 320 and 480 mg kg⁻¹. Chlorpyrifos degradation in the biomixture was monitored over time. Formation of TCP (3,5,6-trichloro-2-pyrinidol) was also quantified, and hydrolytic and phenoloxidase activities measured. The biomixture efficiently degraded chlorpyrifos (degradation efficiency >50%) in all the evaluated maturity stages. However, chlorpyrifos degradation decreased with increasing concentrations of the pesticide. TCP formation occurred in all biomixtures, but a major accumulation was observed in BC30. Significant differences were found in both phenoloxidase and hydrolytic activities in the three maturity stages of biomixture evaluated. Also, these two biological activities were affected by the increase in pesticide concentration. In conclusion, our results demonstrated that chlorpyrifos can be degraded efficiently in all the evaluated maturity stages.     

西部大开发政策效应评价

经过15年的西部大开发,西部各个省份的综合发展水平怎样?西部大开发是否显著缩小西部与东部地区在综合发展水平和经济增长的差异?哪些政策起到了关键作用?是本文将要探讨的问题。研究方法主要是通过模型与数据的实证研究方法对西部大开发的政策效应进行评价。内容包括:一是通过构建包含了社会、经济、科教与文化、对外开放和资源与环境五大类25个分项指标的综合发展水平评价体系,使用从1997到2013年31个省市的指标数据,并计算出综合评价值来考察西部大开发政策对西部地区各个省份整体发展的影响。从评价值排名上来看发现只有重庆、陕西、四川和内蒙古综合发展水平排名提升明显,而新疆、宁夏和青海发展差距还在拉大,其他省份排名变化不大。从分类指标来看,西部地区整体上社会发展和资源环境与生态提升较为明显,说明中央对于公共服务的转移支付和"退耕还林还草"等保护环境与生态的政策起到了一定的成效。二是选取了交通基础设施建设、中央转移支付和税收优惠这三个主要政策作为计量模型的政策变量,分别考察西部大开发整体和分项政策对于综合发展水平和经济增长率的影响。通过系统GMM方法估计整体西部大开发整体政策效应,以2000年前后对比,政策实施对GDP增长率的提升并不显著,综合发展水平也没有收敛。而以2008年为时间节点,综合发展水平和经济增长速度都得到了显著提升。通过DID估计分项政策,结果表明基础设施投入和转移支付能够有效提升综合发展水平和经济增长速度,税收优惠提升相对较弱。本文建议:在交通基础设施投入方面继续对西部地区予以倾斜,特别是建设西部地区通往东中部地区的交通大通道;培育和完善西部地区的市场经济体系,政府较少干预企业投资决策;加强对于西部落后地区、偏远地区的公共产品投入,加强扶贫工作。     

化工园区污水特征分析及生物毒性研究

对天津市某化工园区9个主要污染企业及总排放口的废水进行监测分析,测定了12项水质常规指标和8项重金属指标,采用主成分分析法和生物毒性测试对化工区废水的水质进行了综合评价。结果表明,水质指标中大部分常规项目(如COD、氨氮和重金属含量)在多数企业污水中都符合排放标准,总氮、总磷污染较重,其中磷的污染最严重,最高超标23.83倍;影响污水性质的第一主成分为氯化物、电导率、全盐量和Cr,第二主成分为溶解氧、悬浮物、氨氮、总氮、总磷和As;废水具有一定的生物毒性,且不同化工企业之间毒性差异较大。水质化学测定的结果和生物毒性程度有一定相关性,但也存在差异,应该结合两者综合评价水质污染特征。