The chronic toxicity of fenoxycarb to larvae of the grass shrimp,Palaemonetes pugio

Abstract

This study examined effects of fenoxycarb, a carbamate insecticide, on larvae of the grass shrimp, Palaemonetes pugio. In laboratory experiments, grass shrimp larvae were exposed to fenoxycarb from hatch to postlarval metamorphosis in a chronic, static renewal bio assay. LC50's ranged from 0.92 mg/L at 96 h to 0.35 mg/L at the end of the study (24 days). In assessing sublethal effects of fenoxycarb, postlarval emergence was significantly (p < 0.05) reduced in exposed grass shrimp as compared with controls, and the time to reach postlarval status was significantly (p < 0.05) increased in exposed grass shrimp. Significant differences were not found in other sublethal parameters including postlarval dry weight and intermolt duration. Analysis of fenoxycarb from spiked seawater samples showed concentrations declined by 32 to 42% after 24 h.     

Environmental and Potential Health Effects of Growing Leafy Vegetables on Soil Irrigated Using Sewage Sludge and Effluent: A Case of Zn and Cu

Abstract

The use of sewage sludge and effluent as a source of nutrients and water for crop production is increasing worldwide. A study was conducted in 2001 at Pension farm (near Harare) to determine the effect of long term (>30 yrs) application of sewage sludge and effluent on Zn and Cu accumulation in top soil, uptake of these metals by lettuce (Lactuca sativa L.) and mustard rape (Brassica juncea L.), and dry matter yield. Application of sewage sludge/effluent significantly (p < 0.001) increased total Zn (13.7–1563.9 mg kg^?1) and Cu (2.5–133.3 mg kg^?1) in the top soil (0–20 cm depth) compared to the control. Sewage sludge/effluent addition significantly (p < 0.001) increased Zn uptake by both test crops, while Cu uptake was significant in the first crop of lettuce and the second crop of mustard rape. Based on the dietary patterns of poor urban households in Zimbabwe, the maximum possible intake of Cu will only constitute 40% the Maximum Daily Intake (MDI). The toxicological implications for Zn will however be more severe, exceeding the MDI by 77% through exposure by lettuce consumption and by 251% consumption of mustard rape. It was concluded that long-term addition of sewage sludge/effluent to soil at Pension farm had increased the concentration of Zn and Cu in top soil to levels that pose environmental concern. The consumption of leafy vegetables produced on these soils pose a health risk to poor communities that reside around the study site, especially children, through possible Zn toxicity.     

Environmental impact assessment (EIA): Equilibrium fugacity calculations and worst case approach

A mathematical model UNITRISK which can be used for screening purposes and risk ranking was set up to calculate relative risk values of single chemicals and mixtures of chemicals towards single or mixtures of organisms via contamination of air, water, soil and food dose. The concentration values are calculated by applying the fugacity concept or a dose must be defined. The dose-response is assumed to be linear versus concentration and degradative processes are not considered which is the worst case. The assumption that equilibria between the environmental phases exist is simplifying the model and is also representing the worst case. A mean risk factor is calculated which is 1 if the endpoint values (LC₅₀, LD₅₀, ADI, etc.) are exceeded for the investigated organisms and man.     

Discharge of oilfield-produced water in nueces bay,texas: A case study

During oil and gas production, water is often extracted from geological formations along with the hydrocarbons. These "produced waters" have been discharged to Nueces Bay since the turn of the century. These effluents were found to be highly toxic, and sediments in the vicinity of the discharges were also toxic. We developed a map of wells and produced-water discharge sites in the vicinity of Nueces Bay and identified numerous unplugged wells suitable for conversion to produced water disposal wells. An economic analysis of conversion to subterranean injection of produced water indicates that most of the wells currently in production could pay out the cost of conversion to injection in one to three years. The use of one injection well for two or more water-producing wells could yield greater savings. Wells that could not support the cost of injection are small producers, and their loss would not constitute a major loss of jobs or dollars to the area. This study could serve as a useful model for evaluating the economic feasibility of conversion to injection in other areas of Texas and Louisiana.     

重金属对方形网纹溞的毒性研究

在静置换水条件下，研究了重金属对方形网纹的急性毒性和生活周期毒性。Ｈｇ２＋、Ｃｕ２＋、Ｃｒ６＋和Ｚｎ２＋在２５±１℃下对方形网纹的４ｓｈＥＣ５０分别为０．０１００、０．０２５４、０．１４４和０．２８２８ｍｇ／Ｌ。Ｈｇ２＋对方形网纹的７ｄ生活周期毒性试验，以存活、生长和生殖为毒性指标，未觉察反应浓度（ＮＯＥＣ）为５·９μｇＮＬ，最低觉察反应浓度（ＬＯＥｃ）为１１．８３μｇ／Ｌ，其毒性阈限在二者之间。重金属对方形网纹与大型及鱼类的急性毒性比较和Ｈｇ２＋对类生活周期的毒性比较均表明方形网纹较为敏感。     

对苯二甲酸对鱼类毒性的研究

通过实验室内短期毒实验，评价了对苯二甲酸对鱼草的毒性，给出了对苯二甲酸对草鱼仔鱼及幼鱼的９６ｈＬＣ５０值及其安全浓度。     

生物标志物

生物标志物技术是常规生物检测方法的必要补充，其在环境管理，风险性评价和生态恢复方面有着较广泛的应用，该文主要介绍了相对于常规生物检定方法而言，生物标志物所具备的优点，以及常用生物标志物的类型，生物标志物在环境保护领域的应用等     

小鼠骨髓微核试验评价某市水源水及自来水的遗传毒性

在以往Ａｍｅｓ和ＶＤＳ试验的基础上，运用小鼠体内微核试验检测了某市自来水公司所属的８个水厂水源水、自来水及２个新拟建水厂源水的有机提取物的遗传毒性。结果表明，除２个新拟建水厂的源水外，该市原来的水源水和自来水，均可不同程度地诱导小鼠微核率的升高，并有明显的剂量反应关系。这说明，该市原来的水源水已受到不同程度的污染，而２个新拟建水厂的取水点则水质较好。     

用细胞电泳率指标检测膜毒性物质的探讨

细胞电泳地是近期发展起来的一种检测细胞膜表面微小改变的生物学方法，当膜表面电荷密度分布受影响时，细胞在等强度电场作用下的移动速率会发生改变，根据电泳速率的改变，可以判断外源性物质对细胞膜是否具损伤作用。     

Bioavailability of zinc in runoff water from roofing materials

Corrosion and runoff from zinc-coated materials and outdoor structures is an important source for the dispersion of zinc in the environment. Being part of a large inter-disciplinary research project, this study presents the bioavailability of zinc in runoff water immediately after release from the surface of 15 different commercially available zinc-based materials exposed to the urban environment of Stockholm, Sweden. Runoff water was analysed chemically and evaluated for its possible environmental impact, using both a biosensor test with the bacteria Alcaligenes eutrophus (Biomet^®) and the conventional 72 h growth inhibition test with the green alga Raphidocelis subcapitata. Chemical speciation modelling revealed that most zinc (94.3–99.9%) was present as the free Zn ion, the most bioavailable speciation form. These findings were confirmed by the results of the biosensor test (Biomet^®) which indicated that all zinc was indeed bioavailable. Analysis of the ecotoxicity data also suggested that the observed toxic effects were due to the presence of Zn²⁺ ions. Finally, regression analysis showed that, for this type of runoff samples, the rapid screening biosensor was capable of predicting (a) the total amount of zinc present in the runoff samples (R² of 0.93–0.98; p<0.05) and (b) the observed 72 h-EbC₅₀s (R² of 0.69–0.97; p<0.05).