Pesticides and Essential Minerals Modify Endogenous Antioxidants and Cytochrome P450 in Tissues of Rats

Two experiments were conducted in male Sprague Dawley (SD) rats (175–200 g) to determine changes in the activities of endogenous antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPX), cytochrome P450 (ethoxyresorufin deethylase; EROD) and concentrations of glutathione (GSH) in the blood, liver, and small intestinal mucosa (IM). In both experiments, six rats/group were fed diets based on the AIN-93M diet (Control) or the same modified to contain either 500 mg calcium (Low Ca), 7 mg Zn (Low Zn): 2 mg copper (Low Cu), 60 mg zinc (High Zn) or 12 mg copper (High Cu) in the following combination: Control, LCa/LZn, LCa/LZn/LCu, or HZn/HCu, with and without a pesticide mixture containing acephate, endosulfan, and thiram at 25% LD₅₀ for four or two weeks. Pesticides decreased feed intake and weight gain in all groups by 28%. Erythrocyte SOD was higher than control in the HZn/HCu group and in the LCa/LZn/LCu and HZn/HCu groups with pesticide (P# 0.05). Plasma GPX declined by more than 55% in all the groups with and without pesticides compared to the control. The LCa/LZn/LCu and HZn/HCu diets with and without pesticides reduced GPX in the IM by up to 88%, 40%, and 74%, respectively, than the control. Plasma GSH was about 20% higher than the control in most groups with and without pesticides in the diet. Liver and IM GSH were higher than the control in the HZn/HCu group, whereas IM GSH concentrations were lower than the control in the LCa/LZn and LCa/LZn/LCu groups (P#0.05). All three experimental diets with and without pesticides had a significant effect on liver EROD activity (P#0.05). The results indicate that endogenous antioxidants and EROD were independently modified by dietary zinc and copper levels and pesticides.     

The Combination of Zinc Compounds and Acidic pH Limits Aerobic Growth of a Salmonella typhimurium Poultry Marker Strain in Rich and Minimal Media

Abstract

The objective of the present study was to examine the combined effects of zinc compounds with different acidic pH levels on the aerobic growth of a S. typhimurium poultry isolate in either rich or minimal media. When overall main effects of pH levels of medium or concentrations of Zn compounds were compared, growth rates of the S. typhimurium poultry isolate were significantly ( p < 0.05) decreased by stepwise increase of pH levels of medium (pH 4, 5, 6, and 7) or concentrations (0.67, 3.35, and 6.03%) of Zn compounds (Zn acetate and Zn sulfate). In general growth rates of S. typhimurium poultry isolate appeared to be more reduced by Zn acetate than by Zn sulfate and more reduced in minimal media compared to rich media.     

Monitoring, assessment and modelling using water quality data in the Saale River Basin, Germany

The European Water Framework Directive (WFD) is the overall driver for this environmental study and currently requires the identification of patterns and sources of pollution (monitoring) to support objective ecological sound decision making and specific measures to enhance river water quality (modelling). The purpose of this paper is to demonstrate in a case study the interrelationship between (1) hydrologic and water quality monitoring data for river basin characterization and (2) modelling applications to assess resources management alternatives. The study deals with monitoring assessment and modelling of river water quality data of the main stem Saale River and its principal tributaries. For a period of 6 years the data, which was sampled by Environmental Agencies of the German states of Thuringia, Saxony and Saxony-Anhalt, was investigated to assess sources and indicators of pollution. In addition to the assessment a modelling exercise of the routing of different pollutants was carried out in the lower part of the test basin. The modelling is a tool to facilitate the evaluation of alternative measures to reduce contaminant loadings and improve ecological status of a water body as required by WFD. The transport of suspended solids, salts and heavy metals was modelled along a selected Saale reach under strong anthropogenic influence in terms of contaminants and river morphology between the city of Halle and the confluence with the Elbe River. The simulations were carried out with the model WASP5 which is a dynamic flood-routing and water quality model package developed by the US Environmental Protection Agency.     

Speciation of zinc in contaminated soils

The chemical speciation of zinc in soil solutions is critical to the understanding of its bioavailability and potential toxic effects. We studied the speciation of Zn in soil solution extracts from 66 contaminated soils representative of a wide range of field conditions in both North America and Europe. Within this dataset, we evaluated the links among the dissolved concentrations of zinc and the speciation of Zn(2+), soil solution pH, total soil Zn, dissolved organic matter (DOM), soil organic matter (SOM) and the concentrations of different inorganic anions. The solid-liquid partitioning coefficient (K(d)) for Zn ranged from 17 to 13,100Lkg(-1) soil. The fraction of dissolved Zn bound to DOM varied from 60% to 98% and the soil solution free Zn(2+) varied from 40% to 60% of the labile Zn. Multiple regression equations to predict free Zn(2+), dissolved Zn and the solid-liquid partitioning of Zn are given for potential use in environmental fate modeling and risk assessment. The multiple regressions also highlight some of the most important soil properties controlling the solubility and chemical speciation of zinc in contaminated soils.     

鲫鱼对铜和锌的吸收蓄积研究

用原子吸收分光光度法研究铜和锌在鲫鱼体内积累行为,结果表明,溶解态和颗粒态铜和锌在鱼鳃、肌肉中的积累量随其浓度的增加而增加。铜和锌积累能力的大小顺序为锌〉铜。鱼鳃和肌肉对溶解态和颗粒态重金属的积累能力为鱼鳃大于肌肉,蓄积曲线表现为逐渐趋向平缓的形式。颗粒态鱼鳃积累尤其大于肌肉,说明鱼在对颗粒态铜和锌的积累过程中,部分颗粒态金属是吸附在鱼鳃上的。由于生理功能不同,鲫鱼对锌需要量比铜多。     

Toxicity of tire wear particle leachate to the marine macroalga, Ulva lactuca

Tire wear particles filed from the treads of end-of-life vehicle tires have been added to sea water to examine the release of Zn and the toxicity of the resulting leachate and dilutions thereof to the marine macroalga, Ulva lactuca. Zinc release appeared to be diffusion-controlled, with a conditional rate constant of 5.4 μg[L(h)^1/2]⁻¹, and about 1.6% of total Zn was released after 120 h incubation. Exposure to increasing concentrations of leachate resulted in a non-linear reduction in the efficiency of photochemical energy conversion of U. lactuca and, with the exception of the undiluted leachate, increasing accumulation of Zn. Phototoxicity was significantly lower on exposure to equivalent concentrations of Zn added as Zn(NO₃)₂, suggesting that organic components of leachate are largely responsible for the overall toxicity to the alga. Given the ubiquity and abundance of TWP in urban coastal sediments, the generation, biogeochemistry and toxicity of tire leachate in the marine setting merit further attention.     

Farmyards, an overlooked source for highly contaminated runoff

Summer sampling of storm runoff generated from areas of roofs and hardstanding situated on four dairy/beef farms has provided novel information regarding its microbiological and chemical quality. All farm hardstandings generated runoff that was contaminated with respect to those pollutants (faecal coliforms, FC, and faecal streptococci, FS, major nutrients, organic carbon) that are ubiquitously associated with faecal matter and urine. The separate analysis of roof runoff indicated that these can contribute significant concentrations of FS, phosphorus (P) and potentially toxic elements such as zinc (Zn), and suggests a level of 'background' contamination originating from wash-off of bird droppings and in the case of Zn galvanised surfaces. On average hardstanding runoff showed enhanced concentrations of >4 orders of magnitude for FC and 2-3 for major nutrients and carbon relative to roof runoff. Organic forms of nitrogen (N) and P contributed significantly (averaging >40%) to the total dissolved fraction in both roof and hardstanding runoff. Part of the substantial variability in composition of runoff samples could be attributed to differences between farms as well as the timing of sample collection during individual storms. Where situations allowed, a comparison of water upstream and downstream of the farmyard demonstrated they acted as a source of multiple contaminants not only during hydrologically active storm events but also during dry periods. Contamination pathways included a combination of both point (e.g., septic overflows) and non-point (e.g., seepage from livestock housing) sources. Farmyards situated within intensive livestock farming areas such as SW Scotland, would be expected to have significant local and accumulated downstream impacts on the aquatic environment. Localised impacts would be particularly important for headwaters and low order streams.     

Environmental risk assessment of metals: tools for incorporating bioavailability

In this paper, some of the main processes and parameters which affect metal bioavailability and toxicity in the aquatic environment and its implications for metal risk assessment procedures will be discussed. It has become clear that, besides chemical processes (speciation, complexation), attention should also be given to physiological aspects for predicting metal toxicity. The development of biotic ligand models (BLMs), which combine speciation models with more biologically oriented models (e.g. GSIM), has offered an answer to this need. The various BLMs which have been developed and/or refined for a number of metals (e.g. Cu, Ag, Zn) and species (algae, crustaceans, fish) are discussed here. Finally, the potential of the BLM approach is illustrated through a theoretical exercise in which chronic zinc toxicity to Daphnia magna is predicted in three regions, taking the physico-chemical characteristics of these areas into account.     

ZnO/氧化石墨烯的制备及其对亚硝酸盐的光催化降解

利用沉淀法制备了ZnO光催化剂,并将其负载在氧化石墨烯上,制得ZnO/氧化石墨烯复合材料,研究了该复合材料对亚硝酸钠的光催化降解效果。采用XRD和SEM技术对光催化剂进行表征。考察了初始亚硝酸钠质量浓度、溶液pH、ZnO/氧化石墨烯加入量对亚硝酸钠降解效果的影响。表征结果显示：ZnO/氧化石墨烯晶体的晶型发育良好、结晶度高;新生成的混晶结构提高了催化剂的光催化活性。实验结果表明：在初始亚硝酸钠质量浓度246 mg/L、溶液pH 5、ZnO/氧化石墨烯加入量1.0 g/L的条件下,经过150 min的紫外光降解,亚硝酸钠的质量浓度降至70 mg/L,亚硝酸钠的降解率为71.38%;ZnO与氧化石墨烯的协同效应有效提高了光催化反应体系的效率,ZnO/氧化石墨烯对亚硝酸钠的降解能力远高于氧化石墨烯和ZnO。     

三种添加剂对矿冶区多种重金属污染土壤的修复效果评估——大豆苗期盆栽实验

以湖南省水口山矿冶区周边的农田土壤为供试土壤,通过人工添加化学改良剂的植物盆栽实验,研究了添加不同量的赤泥(质量分数1%、2%、5%)、磷灰石(质量分数1%、2%、5%)、亚硒酸钠(0.1、1、5 mg·k-1,以硒计)对苗期大豆生长及其吸收重金属As、Cd、Cu、Pb、Zn的影响.结果表明,添加5%赤泥明显提高了土壤...