Occurrence and dominance of Cylindrospermopsis raciborskii and dissolved cylindrospermopsin in urban reservoirs used for drinking water supply,South China

The tropical cyanobacterium Cylindrospermopsis raciborskii is of particular concern for its invasive characteristics and production of the toxin cylindrospermopsin (CYN). The present study represents the first attempt to determine the distribution of C. raciborskii and CYN in tropical China. The presence of C. raciborskii and CYN, as well as the composition of phytoplankton, was determined from a total of 86 samples from 25 urban reservoirs for drinking water supply in Dongguan City of South China. The presence of C. raciborskii was observed in 21 of the 25 reservoirs and confirmed that this species has been widely distributed in the investigated reservoirs. C. raciborskii accounted for between 0.1 and 90.3 % of the total phytoplankton biomass and contributed to the majority of the phytoplankton in some reservoirs such as Tangkengbian and Xiagongyan. Its biomass was negatively correlated with NO₃ ^?-N concentration and Secchi depth. Dissolved CYN was detected in more than one-half of the reservoirs with concentrations up to 8.25 μg L^?1, and it positively correlated with C. raciborskii biomass. Dissolved microcystins (MCs) were detected in 12 of the 25 reservoirs with a maximum concentration 1.99 μg L^?1. Our data strongly suggest that C. raciborskii and CYN could be important health hazards in urban reservoirs of South China and that more data are needed for further assessment.     

Occurrence,sources, and ecological risks of PBDEs,PCBs, OCPs,and PAHs in surface sediments of the Yangtze River Delta city cluster,China

Polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in 25 surface sediments in three cities (Nantong, Wuxi, and Suzhou) in the Yangtze River Delta, eastern China were measured. The mean concentrations were 378, 45.8, 1.98, 4,002 ng/g for PBDEs, OCPs, PCBs, and PAHs, respectively. Their levels in the sediments in the three cities were generally consistent with the city industrialization. PBDEs and OCPs were markedly dominated by deca-BDE (>90 %) and DDTs (>70 %). A principle component analysis of the analytes identified three major factors suggesting different sources of the contaminants in the sediments. PBDEs and the organic carbon in the sediments have common sources from industrial activities; whereas OCPs and PCBs, correlated with the second factor, were mainly from historical sources. The third factor with loadings of PAHs is indicative of various combustion sources. Ecological risk assessment indicated that the potential highest risk is from DDTs, for which 22 sites exceed the effects range low (ERL) values and three sites exceed the effects range median (ERM) value.     

盾构隧道施工对邻近建筑物差异沉降与扭曲变形影响分析∗

针对盾构隧道施工侧穿既有建筑物问题,结合南京地铁一号线北延段工程,以盾构隧道侧穿某浅基础建筑物为研究对象,通过对建筑物沉降实测数据进行分析,并利用Plaxis 3D 软件建立数值模型,研究了隧道距建筑物不同水平距离和盾构以不同角度穿越对建筑物差异沉降与扭曲变形特征的影响。结果表明：随着盾构开挖面逐渐接近建筑物,建筑物差异沉降及扭曲变形逐渐增大;差异沉降量在盾构机通过时达到最大值,之后趋于稳定,而扭曲变形峰值出现在盾构开挖面到达建筑物中点截面位置时,随后逐渐减小;当建筑物中心至隧道轴线的水平距离与隧道外径之比L/D=0.5~2 时,建筑物差异沉降量较大,在L/D=1.5 时达到峰值;当盾构穿越夹角从θ=0°增大至θ=90°时,建筑物最大差异沉降量不断增加,而最终扭曲变形值则先增大后减小,在θ=45°时扭曲变形达到峰值。研究结果可为盾构隧道侧穿浅基础建筑物时相关类似工程提供参考。     

EDTAD-modified cassava stalks loaded with Fe3O4: highly efficient removal of Pb2+ and Zn2+ from aqueous solution

Environmental Science and Pollution Research - In this study, a novel magnetic cassava stalk composite (M-EMCS) was prepared through modification with ethylenediamine tetraacetic anhydride (EDTAD)...     

Quantification of the Exposure–Lag–Response Association Between Air Pollution and Respiratory Disease Morbidity in Chongqing City,China

Environmental Modeling & Assessment - The health effects of air pollution on respiratory disease morbidity and mortality commonly vary with air pollutants’ intensity and latency after...     

Response relationships between abrupt seasonal temperature changes/warming (cooling) hiatuses in China and their influencing factors

Environmental Science and Pollution Research - The mechanisms of abrupt seasonal temperature changes and warming (cooling) hiatuses remain unclear. Clarifying how they respond to various...     

应用概率理论拓宽MPN值的计算与实用性

应用多管法检测大肠菌群细菌数是一种适用各种水样的行之有效的检验方法，但此方法操作繁琐，数据处理较难。本文应用概率理论，推导出多种情况下大肠菌群最可能数ＭＰＮ值计算公式，并编制了方便可靠的ＨＢＧ程序，从而进一步提高了此法的实用价值。     

川江流域的土壤退化与防治

川江流域地区土壤退化按肥力因素分类，并以专家系统确定的指标分类统计表明：土壤物理性退化中以水分不调、过砂和板结化较严重；土壤结构性退化中，以土层浅薄化较显著；土壤营养性退化中，以缺硼、钼、磷较突出，成因主要是生态脆弱、土壤侵蚀作用和过渡开发利用，据此提出了防治退化的基本措施。并从持续发展角度提出了适应该区土壤退化特点的持续农业系统。     

长江经济开放开发带湖北科技发展态势及对策

湖北长江经济带的开放开发是在经济发展具有一定实力基础上的再开放再开发，只有以科技为主导，才能使其立足高起点，体现高水平，实现新突破，要始终把握“围绕一条主线，把握两个坚持，努力实现四化”的指导思想，着力建设湖北沿江高新产业带，星火技术密集带，信息公路网络带（一江三带），使湖北长江经济带成为我国中部的科技走廓，为此，要优化科技资源配置，提高研究开发投资水平，建设“八个中心”健全科技服务体系，完善宏观     

三层复合铝合金板材的复合工艺和结合机制

研究了Al-Si/Al-Mn/Al-Si三层复合板热轧复合工艺,借助金相显微镜、扫描电镜、能谱仪分析了复合工艺参数对轧后结合强度和剥离面形貌的影响,得到了优化热轧复合工艺,并对热轧复合板界面结合机制进行了探讨.