Source apportionment of DDTs in maricultured fish: a modeling study in South China

Fish is one of the most important nutrition sources for humanity. Contaminant exposure risk in fish farming will eventually deliver to the crowd through diet. China is the largest fish producing as well as exporting country, where mariculture plays an important role in fish production, especially in South China. Previous investigations indicated that a variety of compartments in farming areas of South China Sea were polluted by persistent organic pollutants, including DDT (dichlorodiphenyltrichloroethane) and its derivatives, some of which is designated as DDTs. In the present study, Hailing Bay and Daya Bay of Guangdong Province, China, were selected as the study sites and DDTs as the target compounds. A fish enrichment model was developed to assess the relative contributions of various pathways to the mass loadings of DDTs in the fish. Average concentrations (and concentration ranges) of DDTs in various environmental compartments of Hailing Bay and Daya Bay were included in modeling and analysis. Modeling results indicated that fish food and seawater contributed approximately the same proportions for the DDTs in maricultured fish. Antifouling paint was supposed to be the primary source of water DDTs in mariculture zone of Hailing Bay and Daya Bay, which contributed 69 % of the total DDTs to the mariculture water. We suggest that in order to protect people from consuming highly contaminated maricuture zone fish, the most effective and feasible methods are using environment-friendly antifouling paint and applying less polluted fish food in the fish reproduction process.     

Preparation of hydrogen-rich gas from waste polyurethane foam by steam gasification and catalytic reforming in a two-stage fixed bed reactor

Journal of Material Cycles and Waste Management - The reclamation of waste rigid polyurethane foam (WRPUF) is capable of realizing both circulations of waste and protection of the environment. In...     

基于区域网络人员疏散模型的计算机仿真

在分析国内外已有安全疏散模型的基础上,结合区域模型思想,提出了以功能单元为基础的精细网格区域疏散模型(区域网格疏散模型).区域网格疏散模型根据建筑单元的功能设置各单元的人员密度,而疏散过程中人员运动速度受人员密度的影响.以MATLAB为开发平台,完成了界面窗口建立、各控件内部计算处理函数语句编程等工作,开发了区域网格疏散仿真程序(Zone Grid Evacuation Simulation Software,ZGESS).该程序可显示各楼层不同时刻的人员分布情况及整个建筑物人数随时间的变化.对建筑人员疏散的实例分析表明,区域网格疏散仿真程序能够模拟人员疏散的运动过程,并可将各单元及整个区域内的疏散全过程动态显示出来.     

膨胀珍珠岩负载Eu3+-TiO2催化剂的制备及其催化性能

以膨胀珍珠岩(EP)为载体,采用溶胶-凝胶法制备了Eu3+-TiO2/EP催化剂.通过XRD和SEM等方法对催化剂进行了表征,以对硝基苯酚溶液为目标物,进行了催化剂活性的研究.实验结果表明,Eu3+的掺杂有效抑制了TiO2晶粒的增长,减小了晶粒尺寸,提高了晶粒的分散性,明显提高了催化剂的活性.在Eu3+掺杂量(Eu3+与Ti的摩尔比)1.0％、焙烧温度500℃、催化剂加入量6 g/L的最佳条件下,对硝基苯酚去除率达87％.     

Bioaccumulation,subcellular, and molecular localization and damage to physiology and ultrastructure in Nymphoides peltata (Gmel.) O. Kuntze exposed to yttrium

Bioaccumulation, subcellular distribution, and acute toxicity of yttrium (Y) were evaluated in Nymphoides peltata. The effects of Y concentrations of 1–5 mg L^?1 applied for 4 days were assessed by measuring changes in photosynthetic pigments, nutrient contents, enzymatic and non-enzymatic antioxidants, and ultrastructure. The accumulation of Y in subcellular fractions decreased in the order of cell wall > organelle > soluble fraction. Much more Y was located in cellulose and pectin than in other biomacromolecules. The content of some mineral elements (Mg, Ca, Fe, Mn, and Mo) increased in N. peltata, but there was an opposite effect for P and K. Meanwhile, ascorbate, and catalase activity decreased significantly for all Y concentrations. In contrast, peroxidase activity was induced, while initial rises in superoxide dismutase activity and glutathione content were followed by subsequent declines. Morphological symptoms of senescence, such as chlorosis and damage to chloroplasts and mitochondria, were observed even at the lowest Y concentration. Pigment content decreased as the Y concentration rose and the calculated EC₅₀ and MPC of Y for N. peltata were 2 and 0.2 mg L^?1 after 4 days of exposure, respectively. The results showed that exogenous Y was highly available in water and that its high concentration in water bodies might produce harmful effects on aquatic organisms. N. peltata is proposed as a biomonitor for the assessment of metal pollution in aquatic ecosystems.