Bioaccumulation and excretion of arsenic compounds by a marine unicellular alga,polyphysa peniculus

Polyphysa peniculus was grown in artificial seawater in the presence of arsenate, arsenite, monomethylarsonate and dimethylarsinic acid. The separation and identification of some of the arsenic species produced in the cells as well as in the growth medium were achieved by using hydride generation–gas chromatography–atomic absorption spectrometry methodology. Arsenite and dimethylarsinate were detected following incubation with arsenate. When the alga was treated with arsenite, dimethylarsinate was the major metabolite in the cells and in the growth medium; trace amounts of monomethylarsonate were also detected in the cells. With monomethylarsonate as a substrate, the metabolite is dimethylarsinate. Polyphysa peniculus did not metabolize dimethylarsinic acid when it was used as a substrate. Significant amounts of more complex arsenic species, such as arsenosungars, were not observed in the cells or medium on the evidence of flow injection–microwave digestion–hydride generation–atomic absorption spectrometry methodology. Transfer of the exposed cells to fresh medium caused release of most cell–associated arsenicals to the surrounding environment.     

Effect of selenium oxidation state on cadmium translocation in chamomile plants

Syntheses and spectral characteristics of cadmium(II) compounds (CdSeO₄, CdSeO₃, and Cd(NCSe)₂(nia)₂) containing selenium in oxidation states (VI), (IV), and (-II) are described. In Cd(NCSe)₂(nia)₂, nicotinamide (nia) and selenocyanate anions are bonded to Cd atom as N-donor monodentate ligands. Nicotinamide is coordinated through the ring nitrogen atom. The effects of these selenium compounds as well as Cd(NCS)₂(nia)₂ on the growth and Cd accumulation in roots and shoots of hydroponically cultivated chamomile plants (cultivar Lutea) were studied. In the applied concentration range (12–60 μmol dm⁻³) Cd(NCS)₂(nia)₂ affected neither the length nor the dry mass of roots and shoots. Other compounds applied at 24 μmol dm⁻³ and 60 μmol dm⁻³ significantly reduced dry mass of roots and shoots. Selenium oxidation state in the cadmium compounds affected Cd accumulation in plant organs as well as Cd translocation within the plants, which was reflected in the values of bioaccumulation (BAF) and translocation factors (S/R). Cd amount accumulated by shoots was lower than that in the roots. The highest BAF values determined for Cd accumulation in shoots were obtained with CdSeO₄. Substitution of S with Se in the Cd(NCX)₂(nia)₂ (X = Se or S) caused an increase of Cd translocation into the shoots. Presented at the XVIIIth Slovak Spectroscopic Conference, Spišská Nová Ves, 15–18 October 2006.     

藻类富集微量元素的机理研究

较全面地探讨了藻类富集微量元素的特点及其机理,一定程度上提示了微量元素与藻类之间反应的实质,为其进一步的实际应用奠定了理论基础。     

Tolerance,bioaccumulation and biotransformation of arsenic in freshwater prawn (Macrobrachium rosenbergii)

Tolerance bioaccumulation and biotransformation of arsenic compounds by a freshwater prawn (Macrobrachium rosenbergii) were investigated. M. rosenbergii was exposed to 10, 20, 30 and 35 μg As cm⁻³ of disodium arsenate [abbreviated as As(V)], 25, 50, 100 and 120 μg As cm⁻³ of methylarsonic acid (MMAA), or 100,200, 300 and 350 μg As cm⁻³ of dimethylarsinic acid (DMAA). Tolerances (50% lethal concentration: LC₅₀) of the prawn against As(V), MMAA, and DMAA were 30, 100, and 300 μg As cm⁻³, respectively. The prawn accumulated arsenic compounds directly from aqueous phase and biotransformed them in part. Both methylation and demethylation of the arsenicals were observed in vivo. Highly methylated and less toxic arsenicals were less accumulated in M. rosenbergii.     

多环麝香(PCMs)的环境行为及毒性效应

多环麝香(PCMs)作为重要的人工合成麝香广泛应用于日用品中,目前在各种环境介质中都能检测到PCMs的存在。由于其持续不断地进入环境并能够在生物体内积累,其效应类似于持久性污染物。作为一类新型污染物,PCMs所引起的环境问题受到了广泛重视。本文介绍了PCMs的物理化学性质、来源以及在不同环境介质中的分析方法和污染现状,概述了其在环境中的降解转化、生物富集行为,并总结了其能产生的急性毒性效应、亚慢性毒性效应、内分泌干扰效应和其他潜在的毒性效应,最后讨论了目前研究中存在的问题,并对未来研究进行了展望。今后,应该建立有效的、可比对的标准分析方法,更加系统地进行环境污染现状、迁移转化规律和生物降解代谢途径的研究;重视暴露途径和生物有效性的研究,并与风险评价结合;结合环境中PCMs的污染现状,探讨低剂量长期暴露和复合暴露对生物的影响。     

全氟和多氟化合物环境问题研究

全氟和多氟化合物（PFASs）是一类具有重要应用价值的含氟有机化合物,许多全氟和多氟化合物难以光解、水解和被生物降解,因此具有环境持久性,并可沿食物链累积放大。2009年5月9日,全氟辛烷磺酸（PFOS）及其盐和全氟辛烷磺酰氟被正式列入持久性有机污染物（POPs）名单,由此全氟和多氟化合物成为近年最受关注的新型污染物,其环境问题研究进入到了新的广度和深度。本文将就其分析方法、环境存在、生物累积放大效应、人体暴露和健康效应、新型全氟和多氟化合物等方面的研究,特别是2009年PFOS等被纳入POPs公约以来取得的研究新进展,进行较为全面的综述,并在此基础上对有关发展趋势进行展望。     

蚯蚓对土壤中8:2与10:2氟调醇的生物富集与转化

以蚯蚓(Eisenia fetida)为受试生物,研究了8:2和10:2氟调醇(FTOH)在蚯蚓体内的生物富集特性、清除速率和生物转化等.结果表明,全氟辛酸(PFOA)是8:2 FTOH主要的末端降解产物,全氟癸酸(PFDA)是10:2 FTOH主要的末端降解产物.暴露30 d后,蚯蚓体内的全氟化合物浓度达到最高,分别为PFDA(565 ng/g)8:2 FTOH(505 ng/g)PFOA(179 ng/g)10:2 FTOH(148 ng/g).清除阶段8:2 FTOH,10:2 FTOH,PFOA和PFDA半衰期(t1/2)分别为23.1 d,16.5 d,5.8 d和11.4 d,其对应的清除速率常数(ke)分别为0.03/d,0.042/d,0.12/d,0.061/d,说明长碳链的PFCAs更难从生物体内清除,母体化合物FTOHs在蚯蚓体内的持久性更强.     

闽江某河段河蚬组织中多环芳烃和有机氯农药的蓄积特征

用GC／MS和GC-μECD测定了闽江某河段河蚬体内多环芳烃（PAHs）和有机氯农药（OCPs）的含量，并分析了河蚬各器官组织中的蓄积特征．结果表明：河蚬体内鳃、肌肉以及内脏团中检测到的PAHs的总量分别为1322．03，397．24，951．04ng／g干重，河蚬易累积低分子量的PAHs，主要是3环PAHS，鳃、肌肉和内脏团中检测到的3环芳烃的比率分别为62．23％，47．04％和36．96％；河蚬对OCPs的蓄积种类主要是DDT类和HCH类农药，OCPs在河蚬鳃、肌肉以及内脏团中的总含量相差不大，分别为19．73，25．46，23．06ng／g干重，河蚬肌肉和内脏团中OCPs的含量与整体中OCPs的含量相关性较好（R^2=0．98和R^2=0．98），肌肉中含量与整体有机氯的含量相关系数为R^2=0．19．     

羊肚菌菌丝体对镉、铅及其复合污染的生长与富集响应

在平板培养条件下,研究了镉、铅及其复合污染对羊肚菌菌丝体生长的影响,并建立了羊肚菌菌丝体对生长基质中镉、铅生物富集的方法.Cd浓度为0-2mg/L范围内对羊肚菌菌丝体的生长具有刺激作用,Cd Pb浓度为2 80mg/L时气生菌丝很浓密,然后生长势减弱.Cd Pb浓度在8 320-32 1280mg/L范围内,Cd、Pb复合污染的协同作用导致菌丝体干重急剧降低.羊肚菌菌丝体对Cd、Pb均具有生物富集作用,并且随着重金属浓度的增大菌丝体中重金属含量逐渐增大,初步认为在Cd、Pb复合污染条件下,促进了羊肚菌菌丝体对Pb的吸收而抑制了对Cd的吸收.     

藻类去除水体中重金属的机理及应用

重金属污染水体的修复,以及含重金属工业废水的处理关乎地球上生物的健康发展。利用低耗能、高修复效率、环境友好、适用范围广泛的藻类去除水体中的重金属,已越来越受到研究者的关注。本文综述了国内外藻类去除水体中重金属的研究进展。分析了藻类去除重金属的生化结构;重点阐述了藻类吸附及富集重金属的机理;讨论了活藻体和死亡藻体用于水体中重金属去除的应用及影响因素,并比较了两者的适用范围及筛选标准;最后指出此领域尚存在的问题,展望了藻类去除重金属的未来发展方向。