多效唑的微生物毒性检测

多效唑是一种新开发的植物生长调节剂类农药。试验采用微生物毒性检测的力法,以混合细菌为材料,研究多效唑对细菌的生长速度、总脱氢酶活性和硝化作用的影响。结果表明,多效唑属低毒性农药,在一定范围内,各观察指标与多效唑浓度呈显著性负相关,即较低浓度的多效唑对细菌的生理活动有一定的刺激作用。     

我国草原鼠害问题的生态学审视

对我国草原鼠害问题及其防治工作进行了回顾，并从草原生态系统角度分析了我国草原鼠害的成灾原因和成灾规律，据此提出了控制我国草原鼠害的战略措施。根据我国草原鼠害的特点，本文提出的控制战略是：（１）树产草地生态系统的整体效益观，即注重草地畜牧业发展中的生态效益、经济效益和社会效益“三统一”的原则和要求，造成鼠类不适宜的生存环境，促进草地生态系统的良性循环；（２）坚持连续多年的长期鼠情监测，搞好预测预报，     

Modeling of acute cadmium toxicity in solution to barley root elongation using biotic ligand model theory

Protons（H⁺）as well as different major and trace elements may inhibit cadmium（Cd）uptake in aquatic organisms and thus alleviate Cd toxicity.However,little is known about such interactions in soil organisms.In this study,the independent effects of the cations calcium(Ca²⁺),magnesium(Mg²⁺),potassium（K⁺）,H+and zinc(Zn²⁺)on Cd toxicity were investigated with 5-day long barley root elongation tests in nutrient solutions.The tested concentrations of selected cations and trace metal ions were based on the ranges that occur naturally in soil pore water.The toxicity of Cd decreased with increasing activity of Ca²⁺,Mg²⁺,H⁺and Zn²⁺,but not K⁺.Accordingly,conditional binding constants were obtained for the binding of Cd²⁺,Ca²⁺,Mg²⁺,H⁺,and Zn²⁺ with the binding ligand:log K_CdBL5.19,logK_CaBL2.87,logK_MgBL2.98,logK_HBL5.13 and logK_ZnBL5.42,respectively.Furthermore,it was calculated that on average 29% of the biotic ligand sites needed to be occupied by Cd to induce a 50% decrease in root elongation.Using the estimated constants,a biotic ligand model was successfully developed to predict the Cd toxicity to barley root elongation as a function of solution characteristics.The feasibility and accuracy of its application for predicting Cd toxicity in soils were discussed.     

Removal of carbofuran is not affected by co-application of chlorpyrifos in a coconut fiber/compost based biomixture after aging or pre-exposure

Biomixtures constitute the biologically active part of biopurification systems(BPS), which are used to treat pesticide-containing wastewater. The aim of this work was to determine whether co-application of chlorpyrifos(CLP) affects the removal of carbofuran(CFN)(both insecticide/nematicides) in a coconut fiber–compost–soil biomixture(FCS biomixture), after aging or previous exposure to CFN. Removal of CFN and two of its transformation products(3-hydroxycarbofuran and 3-ketocarbofuran) was enhanced in pre-exposed biomixtures in comparison to aged biomixtures. The co-application of CLP did not affect CFN removal, which suggests that CLP does not inhibit microbial populations in charge of CFN transformation.Contrary to the removal behavior, mineralization of radiolabeled14C-pesticides showed higher mineralization rates of CFN in aged biomixtures(with respect to freshly prepared or pre-exposed biomixtures). In the case of CLP, mineralization was favored in freshly prepared biomixtures, which could be ascribed to high sorption during aging and microbial inhibition by CFN in pre-exposure. Regardless of removal and mineralization results, toxicological assays revealed a steep decrease in the acute toxicity of the matrix on the microcrustacean Daphnia magna(over 97%) after 8 days of treatment of individual pesticides or the mixture CFN/CLP.Results suggest that FCS biomixtures are suitable to be used in BPS for the treatment of wastewater in fields where both pesticides are employed.     

New methods for identification of disinfection byproducts of toxicological relevance: Progress and future directions

Disinfection byproducts (DBPs) represent a ubiquitous source of chemical exposure in disinfected water. While over 700 DBPs have been identified, the drivers of toxicity remain poorly understood. Additionally, ever evolving water treatment practices have led to a continually growing list of DBPs. Advancement of analytical technologies have enabled the identification of new classes of DBPs and the quantification of these chemically diverse sets of DBPs. Here we summarize advances in new workflows for DBP analysis, including sample preparation, chromatographic separation with mass spectrometry (MS) detection, and data processing. To aid in the selection of techniques for future studies, we discuss necessary considerations for each step in the strategy. This review focuses on how each step of a workflow can be optimized to capture diverse classes of DBPs within a single method. Additionally, we highlight new MS-based approaches that can be powerful for identifying novel DBPs of toxicological relevance. We discuss current challenges and provide perspectives on future research directions with respect to studying new DBPs of toxicological relevance. As analytical technologies continue to advance, new strategies will be increasingly used to analyze complex DBPs produced in different treatment processes with the aim to identify potential drivers of 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.     

从烟道灰中分离回收铜和锌

采用焙烧——浸出——净化——电解工艺对含铜烟道灰泥进行回收铜锌的工艺条件研究。实验表明,烟道灰泥在650℃焙烧2小时,然后采用20％H_2SO_4在固液比(S:L)为1:3.5和温度为60～65℃条件下浸出1小时,可获得Cu浸出率89％、锌浸出率95％的良好效果。同时,在pH-2、T=100℃条件下,对浸出液采用黄钾铁矾法除铁,使净化液中铁含量小于2g/L。该溶液经电解处理后,可获得电解铜和工业级硫酸锌产品     

Phytoremediation Potential of Aquatic Macrophyte, <Emphasis Type="Italic">Azolla</Emphasis>

Aquatic macrophytes play an important role in the structural and functional aspects of aquatic ecosystems by altering water movement regimes, providing shelter to fish and aquatic invertebrates, serving as a food source, and altering water quality by regulating oxygen balance, nutrient cycles, and accumulating heavy metals. The ability to hyperaccumulate heavy metals makes them interesting research candidates, especially for the treatment of industrial effluents and sewage waste water. The use of aquatic macrophytes, such as Azolla with hyper accumulating ability is known to be an environmentally friendly option to restore polluted aquatic resources. The present review highlights the phytoaccumulation potential of macrophytes with emphasis on utilization of Azolla as a promising candidate for phytoremediation. The impact of uptake of heavy metals on morphology and metabolic processes of Azolla has also been discussed for a better understanding and utilization of this symbiotic association in the field of phytoremediation.     

Pathway of anthracene modification under simulated solar radiation

Exposure of polycyclic aromatic hydrocarbons (PAHs) to sunlight results in rapid structural photomodification generally via oxidation reactions. These PAH modification products are in many cases more toxic than their parent compounds. In this study, anthracene (ANT), a rapidly photooxidized PAH, was irradiated with simulated solar radiation (SSR, 100 μmol m⁻² s⁻¹) in aqueous solution to examine the photomodification pathway. The photoproducts formed were identified by HPLC. The ANT product profile after 9 h in SSR was very complex, with more than 20 compounds detected. The photoproducts formed were anthraquinones, benzoic acids, benzaldehydes and phenols showing the process to be oxidative in nature. Some of the anthraquinones were themselves subject to photooxidation, and were thus intermediates in the product pathway. The kinetics of ANT photooxidation revealed a pseudo first-order reaction with a half-life of 2 h under the SSR source used. The kinetics of product formation allowed deduction of a probable photomodification pathway. This study indicates that PAH photooxidation products are likely to exist as complex, dynamically changing mixtures in PAH contaminated aquatic environments.     

环境中全氟有机物的毒性、检测分析及降解

自全氟有机物广泛使用50多年以来,已经在世界范围内发现一定浓度的全氟有机物,各国研究人员针对该类物质特别是全氟辛酸(PFOA)、全氟辛烷基磺酸(PFOS)进行了一定的研究.介绍了该类物质的污染现状,阐述了全氟有机物的毒性、检测分析技术及降解技术,在此基础上提出了今后的研究方向.