Bioaccumulation processes in ecosystems

The fate of environmental pollutants — the various isotopes of elements, and inorganic or organic compounds — is a fundamental aspect of ecology and ecotoxicology, and bioaccumulation is a phenomenon often discussed in this context. Human activities have drastically altered natural concentrations of many substances in the environment and added numerous new chemicals. An understanding of the processes of bioaccumulation is important for several reasons. 1) Bioaccumulation in organisms may enhance the persistence of industrial chemicals in the ecosystem as a whole, since they can be fixed in the tissues of organisms. 2) Stored chemicals are not exposed to direct physical, chemical, or biochemical degradation. 3) Stored chemicals can directly affect an individual's health. 4) Predators of those organisms that have bioaccumulated harmful substances may be endangered by food chain effects. While former theories on the processes of bioaccumulation focused on single aspects that affect the extent of accumulation (such as the trophic level within the food chain or the lipophilicity of the chemical), modern theories are based on compartmental kinetics and the integration of various environmental interactions. Concepts include results from quantitative structure-activity relationships (QSAR), pharmacokinetics, ecophysiology and general biology, molecular genetic aspects and selection, and finally the structure of communities and man-made alterations in them.     

重金属离子废水处理方法

本文以原料来源和应用效果为基础对有毒重金属废水的治理方法作了较为全面的介绍与论述。指出了今后治理废水的发展方向。     

高纯度PAN基碳纤维及其原丝的研制

对用几种方法制取的高纯度PAN原丝进行了分析对比,选取了以无碱金属引发体系的HNO_3溶液聚合工艺制得原液并纺制了碱金属及碱土金属总含量小于100ppm的高纯级PAN原丝。将其与其余三种一般纯度的PAN纤维以同样氧化、碳化工艺制得了碳纤维,并以密度、质量比电阻、X—光衍射、扫描电子显微镜、热分析及原子吸收光谱等方法研究了高纯碳丝及原丝的特点。     

单柱离子色谱测定碱金属与碱土金属的研究及应用

本文用Shimadzu HIC-6A高效单柱离子色谱仪和Shim-pack IC-CI低容量阳离子色谱柱,研究了不同浓度与不同pH值的淋洗剂对金属离子保留行为的影响,优选4.0 m mol/L HNO_3淋洗同时测定Li~+、Na~+、K~+、R6~+和Cs~+离子以及优选1.25m mol/L乙二胺和5.00m mol/L柠檬酸淋洗同时测定Be~(2+)、Mg~(2+)、Ca~(2+)、Sr~(2+)和Ba~(2+)离子的最佳色谱条件,并用于饮水的测定.本法标准加入回收,碱金属5种离子的回收率达101.2%～103.5%;碱土金属5种离子的回收率达99.80%～107.7%.水样分析,Na~+和K~+离子的RSD为0.86%和1.02%,Mg~(2+)和Ca~(2+)离子的RSD为0.364%和0.70%。     

煤矸石堆积对矿区土壤中重金属的影响

以开采历史达百年煤炭城市-淮南矿区为例,研究煤矸石长期堆积对矿区土壤造成的重金属污染.从不同开采历史的矿井区选择7条土壤采样线,系统采集煤矸石堆附近的土壤样品,使用电感耦合等离子体全谱直读光谱仪(ICP-AES)对土壤中主要有害元素(Cu、Ni、Pb、Zn、Sn、Cr、Co)进行分析,并用沉积物标样(LKSD-1)控制分析质量.研究结果表明煤矸石长期风化、淋溶已导致其堆边土壤中重金属发生累积性污染;不同矿井区土壤中重金属含量呈现随煤矸石堆积和风化时间长短呈递减趋势,且Cu、Co、Zn、Ni、Pb相对较易迁移,其含量在部分矿井区土壤中超过国家土壤一级污染标准,但均未超过二级污染标准,这说明煤矸石中重金属向周围土壤的迁移是一个缓慢过程.     

黄河沉积物中重金属离子的形态转化及释放研究

以黄河包头段上游清洁河段的沉积物为吸附剂,以Pb^2 、Cu^2 、Zn^2 、Cd^2 等多离子溶液为吸附质,开展了重金属离子被黄河沉积物吸附后的再释放,以及吸附作用对重金属形态转化的影响等实验研究．结果表明,重金属离子被黄河沉积物吸附后,各元素均不转入残渣态,Cu^2 和Zn^2 主要向碳酸盐结合态及铁锰氧化物结合态转化,Pb^2 主要向碳酸盐结合态和可交换态转化;Cd^2 主要转入可交换态和碳酸盐结合态．吸附后的赋存形态决定了Cd^2 的释放量及释放能力远远大于其它3种重金属离子,由Cd^2 排放引起的污染不易消除且影响长久．     

用无铅玻璃料研制环保型导电浆料

研究了Li2O,NaF,Al2O3和ZnO对玻璃体系软化温度和熔化温度的影响,在此基础上研制出了软化温度Tg低于500℃、熔化温度Tm低于560℃的低温无铅玻璃.分析了Li2O和NaF等对玻璃体系助熔的机理,用X射线衍射技术(XRD)分析了玻璃料的结晶状态,实验结果表明,制备的B2O3,Bi2O3和SiO2体系玻璃料为微晶玻璃,玻璃体系结构稳定.利用该玻璃料制备出的导电浆料,电性能优良,能满足低温电极的使用需要.     

垃圾焚烧发电厂飞灰浸出毒性的研究

探讨了液固比、初始pH值及浸出时间对飞灰中重金属Pb、Cr、Cd、Ni、Cu、Mn、Hg、As的浸出影响.结果表明:各重金属的浸出量都随着液固比增加而增加,其中Ni、Cu、Mn、Cd的浸出量在液固比大于25后变化较平缓,As在液固比大于60后浸出量有所降低;重金属在浸取液的pH≤1.95时的浸出浓度远远大于其在浸取液的pH≥6.13时的浸出浓度;随着浸出时间的增加,Hg的浸出浓度先下降后上升,Cr的是先上升,30h后变化不大;Cd、Cu、Pb、Ni、Mn浸出时间在2h-6h后浸出浓度迅速减小,As则快速增加,而后都变化不大;在液固比、初始pH值及浸出时间三个影响因素中,pH值对重金属的浸出影响较大,重金属在酸性环境下较易浸出,但Pb在碱性情况下也易于浸出.     

体心立方过渡金属低指数表面单空位的改进分析型嵌入原子法模拟

应用改进分析型嵌入原子法(modified analytical embedded-atom method,MAEAM),计算了7种体心立方(body-centered cubic,BCC)过渡金属Fe、W、Mo、Cr、Ta、Nb和V等低指数(100)、(110)和(111)表面前9层上的单空位形成能.结果表明,对每一种金属,单空位形成能在同一低指数表面层中的第1层最低,且在表面第1层和第2层(Nb除外)随表面原子密度的减小而降低,即E(11f11),1相似文献   

Microbial communities in microcosm soils treated with battery waste

Battery waste is one of the most destructive hazards to our environment,especially to the soil.In order to understand the effects of the battery waste on the microbial communities in soil,microcosm soils were treated with the powder made from the battery waste.Microbial biomass and respiration were measured after 15,30,45,and 60 days of the treatment,and catabolic capability and Bi- olog profile were determined after 60 days.Microbial biomass was declined by all treatments,while microbial respiration and catabolic ca- pability were enhanced.Although microbial biomass recovered after a period of incubation,microbial respiratory quotient,catabolic capa- bility and community structure remained significantly affected.Our results also suggest that microbial respiratory quotient and Biolog pa- rameters are more sensitive than microbial biomass to the battery stress on bioavailability.