单歧藻富集和降解烷基酚类化合物的动力学过程

选择单歧藻(Tolypothrix)研究其对苯酚、邻甲酚、间甲酚和4-辛基酚的生物富集过程及生物降解动力学。5d内单歧藻的生长经历了停滞期、对数期、静止期3个阶段;苯酚、邻甲酚、间甲酚、4-辛基酚的生物富集因子(BCF)平均值为4 59,3 87,5 82,292 48,与KOW值线性相关;单歧藻平均每天降解苯酚、邻甲酚、间甲酚、4-辛基酚分别为2 54,3 17,1 84,0 16mg L;用新近提出的二级反应动力学方程拟合其降解过程,得到它们的生物降解二次动力学常数K分别为0 386,0 500,0 254,0 023,K值由污染物的初始浓度决定并与分子量(M)线性相关,K=-0 003M+0 69,R=0 87,N=4。      

新型杀菌剂氟吡菌胺对9种环境生物的急性毒性及其在斑马鱼体内的生物富集

为评价新型杀菌剂氟吡菌胺对环境生物的毒性风险,避免其在使用过程中对我国特有的环境生物产生危害,测定了氟吡菌胺对意大利蜜蜂、日本鹌鹑、斑马鱼、家蚕、斜生栅藻、大型溞、玉米螟赤眼蜂、赤子爱胜蚓和黑斑蛙蝌蚪等9种代表性环境生物的急性毒性,并以斑马鱼为试材,研究了氟吡菌胺的生物富集性,即根据鱼类急性毒性结果 LC50(96 h)=1.489 mg·L~(-1),设计生物富集试验水样浓度为LC50的1/2、1/10和1/100,即0.745 mg·L~(-1)、0.149 mg·L~(-1)和0.0149 mg·L~(-1),连续暴露8 d,采用液相色谱法测定3个浓度下氟吡菌胺在斑马鱼体内的富集量。结果表明,氟吡菌胺对斑马鱼、斜生栅藻和大型溞3种水生生物的急性毒性为中毒级,对黑斑蛙蝌蚪急性毒性为高毒级,其对蜜蜂、鸟类、家蚕、蚯蚓和天敌赤眼蜂等环境生物均为低毒或低风险;斑马鱼在0.745、0.149和0.0149 mg·L~(-1)的氟吡菌胺水溶液中暴露192 h时,生物富集系数BCF分别为33.65、26.39和193.25;根据化学农药环境安全评价试验准则评价标准,10BCF≤1000,氟吡菌胺属于中等富集性农药。     

氧化石墨烯存在下铜离子对大型溞的毒性研究

氧化石墨烯(graphene oxide,GO)作为一种具有独特物理化学性质的新型纳米材料被广泛应用,其进入环境后可能对传统污染物的毒性造成影响。选取大型溞为受试生物,研究了GO的存在对Cu在大型溞体内的富集、毒性和抗氧化系统的影响。结果表明,GO对Cu~(2+)具有良好的吸附效果,大幅降低了试验液中Cu~(2+)浓度。1 mg·L~(-1)和2 mg·L~(-1)GO存在下,大型溞暴露于19.2μg·L~(-1)Cu~(2+)溶液72 h后,体内的金属Cu富集量由360μg·g-1干重分别降低为308μg·g-1和215μg·g-1干重。GO的存在降低了Cu~(2+)对大型溞的毒性,Cu~(2+)对大型溞的72 h-LC50值由19.2μg·L~(-1)升高至56μg·L~(-1)。Cu~(2+)单独作用时,大型溞体内SOD活性和GSH含量表现为先诱导后抑制,而MDA含量逐渐升高;当GO存在时,大型溞体内酶活性的变化趋势与上述现象类似,但含量总体低于Cu~(2+)单独暴露时的活性和含量。研究表明GO的加入减少了大型溞体内Cu的富集量,降低了Cu~(2+)对大型溞的氧化损害,对Cu~(2+)的毒性存在一定的减轻效果。     

野外条件下土壤砷浓度对蜈蚣草砷富集特征的影响

以As超富集植物蜈蚣草广泛分布的湖南省郴州市为例,调查了不同As污染程度下植物对As的富集和转运特点.结果表明,在野外条件下根际土壤中As浓度相对较低时(64～1000mg/kg),蜈蚣草地上部As浓度随根际土壤中As浓度的增加而逐渐增加,而在根际土壤中As浓度相对较高(1000～2712mg/kg)时,蜈蚣草地上部As浓度表现为逐渐下降的趋势.在调查的所有样点中,蜈蚣草对As的转运系数介于1.08到6.03之间,显示出超富集植物的典型特征.结果还表明,在污染区土壤As浓度存在很大的空间变异性,根际土壤与非根际土壤之间的As浓度也存在很大差异.因此,在野外调查时最好是直接采取距离植物根部最近的根际土壤.     

Environmental impact of leaching of trace elements from fly ash dumps on aquatic ecosystems

Ten sampling points were selected in Kanhan River, situated near the ash dump sites of Koradi Thermal Power Plant, Nagpur. The leaching of trace elements from fly ash dumps was experimentally determined by acid digestion, batch leaching and toxicity characteristic leaching procedure tests. Elemental concentrations in river water, sediment, plankton and five commonly prevailing fish species (Catla catla, Labeo bata, Cyprinus carpio, Cirrhinus reba, Puntius ticto) were determined using a Flame Atomic Absorption Spectrophotometer during the pre-monsoon and post-monsoon seasons. Metal concentrations (Cr, Mn, Zn, Cu, Fe, Ni, Cu and Pb) in river water were higher during the pre-monsoon season compared to the post-monsoon season. Zn (30.65?mg/kg) was observed to be the most predominant metal in plankton during the pre-monsoon season while, during the post-monsoon season, Fe (21.19?mg/kg) showed the maximum concentration. Muscles of C. catla had metal concentrations (Cr, Mn, Zn, Fe, Cu and Pb) above the permissible limits of Food and Agricultural Organization (FAO 1983) during the pre-monsoon season. Bioaccumulation factor (BAF) was found highest for Cr (37.5) in muscles of C. catla during the pre-monsoon season, while BAF was observed to be maximum in L. bata for Cu (28.09), which may be detrimental for human consumption.     

微囊藻毒素在滇池螺蛳各组织中的积累及动态分布

螺蛳是我国的一种特有腹足类,主要分布于云南省的高原湖泊中,是重要的经济螺类。为了探讨微囊藻毒素(MC)在螺蛳各组织中的分布及季节动态规律,于2008年1月及5~10月间按月采集滇池螺蛳样品,用酶联免疫检测法(Enzyme Linked Immuno Sorbent Assay,ELISA)检测了肝脏、消化道、性腺及肌肉中MC含量。结果表明,MC在螺蛳的肝胰腺、消化道、性腺及肌肉中MC的含量均值分别为338±190、272±163、123±097和035±043 μg/g DW;统计分析表明肝胰腺和消化道中MC含量无显著差异,但两者显著高于性腺,性腺显著高于肌肉。MC在各组织中含量最高月份出现在7月,含量最低月份出现在5月。相关性分析表明,性腺和肌肉组织中MC含量与周围环境水体中总MC含量之间显著正相关。按照WHO推荐的人体每日可允许摄入量TDI(≤004 μg/kg人体重)标准进行推算发现,食用螺蛳可能存在潜在的风险。     

Metal accumulation in mosses across national boundaries: uncovering and ranking causes of spatial variation

This study aimed at cross-border mapping metal loads in mosses in eight European countries in 1990, 1995, and 2000 and at investigating confounding factors. Geostatistics was used for mapping, indicating high local variances but clear spatial autocorrelations. Inference statistics identified differences of metal concentrations in mosses on both sides of the national borders. However, geostatistical analyses did not ascertain discontinuities of metal concentrations in mosses at national borders due to sample analysis in different laboratories applying a range of analytical techniques. Applying Classification and Regression Trees (CART) to the German moss data as an example, the local variation in metal concentrations in mosses were proved to depend mostly on different moss species, potential local emission sources, canopy drip and precipitation.     

Application of various methods to determine the lipophilicity parameters of the selected urea pesticides as predictors of their bioaccumulation

Different lipophilicity procedures including a newly developed (based on O?cik's equation) was applied in order to compare various urea pesticides with herbicidal and also insecticidal activity, such as monolinuron, chlorotoluron, diuron, isoproturon, linuron, dimefuron, diflubenzuron, teflubenzuron and lufenuron. Lipophilicity parameters (R_MWS and R_MW0) of nine examined pesticides were determined on the chromatographic plates RP-8F₂₅₄ with the use of methanol–water as a mobile phase_. Similarity analysis enabled to group all examined pesticides depending on their lipophilic character and allowed to perform a more objective comparison of different lipophilicity parameters obtained for investigated compounds by means of thin-layer chromatography and by the use of computational methods. It was stated that with the number of fluorine in examined pesticides, the lipophilic character of insecticides and also their tendency to bioaccumulation in the living systems increases noticeably. The results of this work confirmed that a new procedure for determining the lipophilicity parameter (R_MW0) by O?cik's equation could be a suitable tool in the prediction of pesticide bioaccumulation in living system and may be used as an indicator in design of new urea pesticides, which will be safe for humans and the environment.     

Temporal trend (1988-2008) of hexabromocyclododecane enantiomers in herring gull eggs from the German coastal region

Levels of α-, β-, and γ-hexabromocyclododecane (HBCD) were determined in pooled eggs from herring gulls (Larus argentatus) sampled on three bird sanctuaries near the German North Sea coast between 1988 and 2008 (Mellum and Trischen) and the German Baltic Sea coast between 1998 and 2008 (Heuwiese) and archived by the German Environmental Specimen Bank. Pressurized fluid extraction, gel permeation chromatography, and LC-MS/MS using ¹³C₁₂-labelled isotope standards and a chiral column were applied. α-HBCD was the dominating diastereomer and ranged between 3.7 and 107 ng g⁻¹ lw while β- and γ-HBCD were throughout close to LOQ. The highest α-HBCD concentration was found in eggs from Mellum sampled in the year 2000. Interestingly, HBCD in eggs from the three islands displayed similar time courses with levels increasing to a peak contamination around 2000 and decreasing levels ever since. Chiral signatures of α-HBCD in eggs differed among the islands but indicated a preferential enrichment of the first eluting enantiomer (−)-α-HBCD.