Toxicity andaccumulation of tributyltin chloride on tilapia

Acute toxicity (96 h) and bioconcentration experiments of tributyltin chloride (TBT) in tilapia were conducted in an aqueous solution with salinity of 15‰, and a toxicity mechanism has been suggested. The 96-h LC₅₀ was 3.80 μg Sn l⁻¹. Bioconcentration factors in different tissues increased in the order muscle<gill<viscera. Studies on the metabolism of TBT showed that it can be easily degraded to DBT (dibutyltin) in these tissues. Further degradation of DBT to MBT (monobutyltin) was much more difficult. A mesocosm was used for the first time to study the toxicity of TBT in tilapia. The result demonstrated that the TBT bioconcentration curve changed with the initial concentrations of TBT but the order of bioconcentration in the tissues did not change. © 1998 John Wiley & Sons, Ltd.     

Heavy metal accumulation by selected plant species along the national highway: a case study of Udaipur,Rajasthan, India

ABSTRACT

A detailed research was conducted to find out the heavy metal accumulation by plant species at the roadside. Bioconcentration, bioaccumulation and translocation factors were estimated in 10 individuals of each investigating plant species. The plant and soil samples used in the research were collected along the National Highway-76 from Chittorgarh to Udaipur, Rajasthan, India. The concentration of cadmium and lead in roadside soil, plant roots, stems and leaves shows a correlation. The highest bioconcentration factor of Cd and Pb was 0.22 ± 0.04 and 0.13 ± 0.02 estimated in Bougainvillea spectabilis Willd. The highest translocation factor of Cd was 1.30 ± 0.50 in Pongamia pinnata L., and the highest translocation factor of Pb was 1.63 ± 0.45 estimated for Nerium oleander L. The average concentrations of Cd and Pb were 11.35 ± 1.60 and 223.70 ± 68 mg kg^?1 in investigated roadside soil. The average concentrations of accumulated Cd and Pb in B. spectabilisWilld. were 2.38 ± 0.49, 1.97 ± 0.51, 3.07 ± 0.78 and 29.34 ± 7.82,18.96 ± 5.62, 37.75 ± 12.93 mg kg^?1 in roots, stems and leaves, respectively. The decreasing order of bioaccumulation factor of cadmium in plants was B. spectabilis Willd.>Butea monosperma (Lam.) Taub>Calotropis procera (Ailton) Dryand>N. oleander L.>P. pinnata L. The decreasing order of bioaccumulation factor of lead in plants was B. spectabilis Willd.>P. pinnataL.>B. monosperma (Lam.) Taub>C. procera (Ailton) Dryand>N. oleander L. The B. spectabilis Willd. was identified as a rhizofiltration tool of heavy metals such as Cd and Pb with higher bioconcentration factor. P. pinnata L. for Cd and N. oleander L. for Pb were revealed for phytoextraction technology with high translocator factor to accumulate and eliminate these toxic elements from soil.     

Toxic effect of triphenyltin on Lemna polyrhiza

Little data about toxic effect of triphenyltin (TPT) on aquatic plants is available. The purpose of this paper is to study the toxic effect of TPT on duckweed, Lemna polyrhiza, and the bioconcentration factor of TPT by Lemna polyrhiza. At 5 µg/l concentration TPT treatment, a toxic effect on growth of Lemna polyrhiza appeared. The 8 day IC₅₀ of TPT to Lemna polyrhiza was 19.22 µg/l. TPT stimulated peroxidase activity and nitrate reductase activity at 2 and 5 µg/l. TPT reduced chloroplast activity of Lemna polyrhiza at 2 and 5 µg/l. Bioconcentration factors of TPT for Lemna polyrhiza were 4.3 and 10.9 at 2 and 5 µg/l, respectively. Copyright © 2005 John Wiley & Sons, Ltd.     

用拓扑指数和神经网络研究有机污染物的生物富集因子

在修正Randic的分子连接性指数和连接矩阵的基础上, 定义新型分子连接性指数(mF), 并计算了239种有机污染物的分子连接性指数(mF). 用其1F构建了239种有机污染物生物富集因子(lgBCF)的QSAR模型, 该模型判定系数(R2)及逐一剔除法(LOO)的交互验证系数(Q2)分别为0.747和0.742. 而用1F和4个电性距离矢量(Mk)构建的五元QSAR模型的R2及Q2分别为0.829和0.819. 结果表明, 从统计学的角度, 该模型具有高度的稳定性及良好预测能力. 从此模型可知, 有机污染物BCF的主要影响因素是—C—, ＞C—, —O—, —S—, —X等分子结构碎片以及分子的柔韧性、折叠程度等空间因素. 将5个结构参数作为人工神经网络的输入层结点, 采用5∶26∶1的网络结构, 利用BP算法, 获得了一个令人满意的QSAR模型, 其R2和标准偏差s分别为0.987和0.157, 表明lgBCF与这5个参数具有良好的非线性关系. 从上可见, 新建的连接性指数1F以及电性距离矢量与有机物的生物富集因子具有良好的相关性, 可望在物质构效关系研究中获得广泛的应用.     

气相色谱法估算多环芳烃生物浓缩系数

提出用气相色谱相对比保留体积估算多环芳烃在鱼体内的生物浓缩系数。测定了草鱼对萘、联苯，β－甲基萘２，３－二甲基萘，２，７－二甲基萘，苊，菲７种ＰＡＨ的ＢＣＦ。建立了在６种不同极性色谱固定相上的ＢＣＦ与Ｖｇ的一元回归方程和ＢＣＦ与Ｖｇ（ｒ），一阶分子连接性指数的二元回归方程。     

Nonlinear Dependence of Bioconcentration Factors on n-Octanol-Water Partition Coefficients of Chlorinated Dibenzofurans and Dibenzo-p-Dioxins

Abstract

A nonlinear thermodynamic model is applied to the prediction of both the bioconcentration factor (K_bw) in the guppy (Poecilia reticulata) and the n-octanol-water partition coefficient (K_ow) of chlorinated dibenzofurans and dibenzo-p-dioxins. To this end molar liquid volumes, heats of vaporization and empirically fitted parameters of the pertinent solute and solvents are used. Calculated log K_bw and log K_ow values are obtained with correlation coefficients (r = 0.85 and 0.992) and mean deviations (< dev > = 0.19 and 0.17), which compare favourably with experimental data.

In addition the model enables an explanation of the well-known nonlinear log-log relationship between the two properties for compounds with high K_ow values on the basis of differences between the properties of biotic lipid and n-octanol. It is suggested that the breakdown of the linear relationship is caused by entropic effects related to the number of chlorine atoms in the solute molecules and to the structures of the lipid and n-octanol.     

The physicochemical basis of QSARs for baseline toxicity

The physico-chemical properties relevant to the equilibrium partitioning (bioconcentration) of chemicals between organisms and their respired media of water and air are reviewed and illustrated for chemicals that range in hydrophobicity. Relationships are then explored between freely dissolved external concentrations such as LC50s and chemical properties for one important toxicity mechanism, namely baseline toxicity or narcosis. The ‘activity hypothesis’ proposed by Ferguson in 1939 provides a coherent and compelling explanation for baseline toxicity of chemicals in both water- and air-respiring organisms, as well as a reference point for identifying more specific toxicity pathways. From inhalation studies with fish and rodents, narcosis is shown to occur at a chemical activity exceeding approximately 0.01 and there is no evidence of narcosis at activities less than 0.001. The activity hypothesis provides a framework for directly comparing the toxic potency of chemicals in both air- and water-breathing animals. The activity hypothesis is shown to be consistent with the critical body residue concept, but it has the advantage of avoiding the confounding effect of lipid content of the test organism. It also provides a theoretically sound basis for assessing the baseline toxicity of mixtures. It is suggested that since activity is readily calculated from fugacity, observed or predicted environmental abiotic and biotic fugacities can be used to evaluate the potential for baseline toxicity. Further, models employing fugacity or activity can be used to improve the experimental design of bioassays, thus possibly reducing unnecessary animal testing.     

Potential effects of climate change on the chemical quality of aquatic biota

Climate changes can alter and modify the distribution and the partitioning of contaminants in water bodies through several factors (e.g., rise in temperature, decrease in oxygen through water scarcity, acidification and remobilization of pollutants in sediments due to flooding). Other indirect effects can be linked to climate changes (e.g., increased use of pesticides due to the rise of plant diseases caused by new vectors and erosion of coastal areas due to rise in sea level). All these factors have the potential to enhance the bioavailability of dangerous pollutants with bioaccumulative properties with an increasing risk of transfer in the food chain.The data available on aquatic species for compounds such as, polychlorinated biphenyls, dioxins and mercury show that the legislative standards for food are exceeded in some areas. These data also show that levels in aquatic biota of other emerging compounds with bioaccumulative properties (such as, perfluorinated octane sulfonate, polybrominated diphenyl ethers and hexabromocyclododecane can be relevant in some areas and at some trophic levels. In particular, the effect of climate changes can be relevant in vulnerable water bodies (e.g., estuaries of rivers or coastal lagoons), where fishing, extensive and intensive aquaculture activities and sites of high biodiversity value are often present.For these reasons, there is a need to change the water-monitoring strategies with a focus on analytical methods for biota determination and to have monitoring programs that include detection of long-term trends and share procedures for the setting of quality criteria for biota.