等浓度配比法研究苯酚、硝基苯和间硝基苯胺对发光菌的联合毒性作用

分别测定了苯酚、硝基苯和间硝基苯胺对发光菌的单一毒性,以及等浓度配比和等毒性配比的二元及三元混合体系的联合毒性,采用相加指数法对其联合效应进行了评价。结果表明,等浓度比和等毒性比混合体系的联合作用结果一致:苯酚+间硝基苯胺二元体系为协同作用,其他各体系为相加作用。为简化联合毒性实验方法,建议在研究相关系列化合物的联合毒性作用机制中,可采用等浓度配比方法。     

Toxicity op technical X‐factor∗ to weanling rats. II. A subacute oral study

Abstract

Eighty male weanling rats were fed dietary levels o£ Technical X‐factor (β ‐isomer free BHC, a by‐product obtained during the separation of lindane from Tech. BHC) at dosages of 10, 50, 250, 750, 1500 and 3000 ppm for 90 days. No overt signs of toxicity or mortality were observed at any of the dietary levels. However, a significant reduction in food consumption and growth was evident beyond 750 ppm. Pronounced hepatomegaly observed at 1500 and 3000 ppra was associated with histolo‐gical alterations such as cellular hypertrophy, cyto‐plasmic vacuolisation and focal necrosis. Adrenals showed cortical hypertrophy and highly vacuolated cytoplasm. Though a significant increase in the levels of SGOT was noted at 3000 ppra dosage, no appreciable changes were observed in the levels of SGPT and SLDH. Technical X‐factor appeared to possess low chronic toxicity compared to Tech. BHC as evidenced by the various parameters studied. The observed low chronic toxicity of X‐factor is probably due to the absence of β ‐isomer and altered composition of delta and alpha isomers.     

Comparative toxicity of rac- and S-tebuconazole to Daphnia magna

Tebuconazole is a chiral triazole fungicide used as raceme in a variety of agricultural applications. Earlier studies showed that tebuconazole is toxic to many non-target aquatic organisms but relative data for tebuconazole enantiomers are lacking. Thus, goal of this study was to evaluate and compare the toxicity of rac- and S-tebuconazole with Daphnia magna at both acute and chronic levels according to Organization for Economic Cooperation and Development (OECD) guidelines 202 and 211 respectively, to provide some guidelines for optimizing chiral pesticides application and management. The exposure concentrations were 0.1, 0.5, 1, 2, 4, 8, 10 mg L^?1 for both rac- and S-tebuconazole and their 48-h EC₅₀ values to D. magna were 3.53 (3.32–3.78) and 2.74 (2.33–3.10) mg L^?1 respectively, indicating that these both are medium toxic to D. magna with no significant toxicity difference at acute level. In chronic test, <24-h old D. magna were exposed to 0.01, 0.05, 0.10, 0.20, and 0.40 mg L^?1 of rac- and S-tebuconazole with one blank and one solvent control for 21 days according to OECD guideline 211. Four developmental (molting rate, days to the 1st and 3rd brood, and body length) and five reproductive (size of the 1st and 3rd brood, number of broods, and number of neonates) parameters for each D. magna were determined. Results showed that both rac- and S-tebuconazole significantly reduced the reproduction and impacted the development of D. magna at concentrations of 0.05 mg L^?1 or higher. Furthermore, S-tebuconazole was more toxic than raceme, and the difference between effects on the same parameters induced by rac- and S-tebuconazole was statistically significant. These results demonstrated that the chronic toxicity of S-tebuconazole might be underestimated in general use, and further studies should focus more on the biological behaviors of enantiomers and not just the raceme of tebuconazole and other chiral pesticides in the environment.     

Effect of quinalphos on blood enzymes and its acute toxicity in bubalus bubalis

Abstract

The acute toxic effects of quinalphos (0,0‐diethyl 0–2‐quinoxalyl phosphorothioata) uere investigated in male buffalo calves. Quinalphos was administered in single oral doses of 5, 7.5, 8.5 and 10 mg/kg body wt. and its effects on erythrocyte and plasma cholinesterases, serum aspartate aminotransferase and blood glucose were studied at various time intervals. The lowest dose (5 mg/kg) produced no apparent toxic symptoms. All the animals given highest dose (10 mg/kg) died within 60–82 hours after dosing. Quinalphos at all the dose levels markedly inhibited the erythrocyte and plasma cholinesterases (68–100%) and significantly elevated the levels of serum aspartate aminotransferase and blood glucose. Seven days after the administration of quinalphos, the blood cholinesterases in survivors remained inhibited to the extent of 41–77% whereas the levels of serum aspartate aminotransferase and blood glucose were comparable to control values.     

Physiological effects of tetracycline antibiotic pollutants on non-target aquatic Microcystis aeruginosa

This study aimed to evaluate the aquatic toxicity of three typical tetracycline antibiotics, including tetracycline, oxytetracycline, and chlortetracycline, on the cyanobacterium Microcystis aeruginosa. The cell density, chlorophyll a content, protein content, and enzymatic antioxidant activities were determined. The results showed that the cell growth was significantly inhibited by the three compounds at a low concentration. The chlorophyll a and protein content decreased significantly after exposure to 0.05 mg L^?1 of each compound for 9 d. When exposed to 0.2–1 mg L^?1 of tetracycline, the superoxide dismutase (SOD) activity increased, but peroxidase (POD) and catalase (CAT) activities decreased. In contrast, when exposed to oxytetracycline and chlortetracycline at different concentrations ranging from 0.2 to 1 mg L^?1 and from 0.01 to 0.05 mg L^?1, the SOD activity decreased, but the POD and CAT activities increased. These findings indicate that tetracycline antibiotics influence cell growth and protein synthesis, and they also induce oxidative stress in M. aeruginosa at environmentally similar concentrations. Thus, this study may provide further insights into the toxic effects of tetracycline antibiotics and the controlled use of antibiotics.     

低浓度下4个取代苯污染物与硝酸铅的混合对发光菌的联合毒性

多种污染物混合特别是低浓度下的混合对生物的联合毒性是生态毒理学研究的热点之一。选择了3类污染物苯酚、间甲基苯酚、苯胺、对硝基苯胺、硝酸铅，采用美国微板光度计测定了它们对发光菌青海弧菌．Q67（Vibrio-qinghaiensissp-Q67）的单一及联合毒性。应用非线性拟合技术模拟了这5种物质及其混合物的剂量．效应曲线，硝酸铅可用Logit模型模拟，其它4个物质能用Weibull模型准确描述，所有拟合相关系数在0．98以上，均方根误差在O．02以下。根据纯物质的EC50值，获得这5个物质的毒性强弱顺序：硝酸铅〉对硝基苯胺〉间甲基苯酚〉苯酚〉苯胺。混合实验设计了各物质在EC50、EC1、无观察效应浓度（noobserved effectcon centration，NOEC）比例的混合。用浓度加和（doseaddition，DA）和独立作用模型（independentaction，IA）对混合物毒性进行预测。IA基本准确预测了这5个物质在各自EC50混合的毒性。DA与队模型都稍微过高地预测了以EC。及NOEC浓度比例混合的联合毒性，但都在毒理学实验容许的范围之内。这5个物质以NOEC混合时对测试生物Q67没有产生明显毒性，但是还不能判定这些物质在此浓度下混合是安全的。污染物在各自的NOEC浓度下混合是否对其它生物有潜在的威胁还需更多毒理学实验支持。     

钒渣中钒的浸出特性

对制钒浸出工序进行研究,了解钒渣中钒残留比率及钒含量的变化范围,并对随州、竹山、郧西等地钒厂在不同生产工艺、不同堆放深度、不同排渣年份条件下的钒渣中钒的浸出特性进行了研究。结果表明,渣样中钒含量分布于3.5mg/L～30mg/L,钒在渣中残留比约为4.5%～5.6%,钠化焙烧渣钒含量高于钙化焙烧渣。与砷毒性的类比结果说明,不能排除钒渣属于危险废物的可能。     

Toxicity of Heavy Metals on Scenedesmus quadricauda (Turp.) de Brébisson in Batch Cultures (7 pp)

Background Aquatic environments are often exposed to various pollutants like heavy metals that are released from industrial, agricultural and domestic wastes. Emissions of heavy metals can then enter all ecosystems and bring about severe problems in plants, especially algae depending on the concentrations of a given element. The objective of the investigation presented is to detect toxic effects due to some heavy metals in the biomass of green alga Scenedesmus quadricauda. Methods All experiments were conducted with axenic cultures of the green alga Scenedesmus quadricauda (Turp.) de Brebisson (Chlorococcales, Chlorophyta). The cultures were grown in Chu-no.10 medium, and optimum physical and chemical growth conditions were provided to get higher growth rates and lower doubling times of cells. Growth of the micro algal cultures was measured on a daily schedule by counting cultures and determination of chlorophyll-a. The sterile-filtered heavy metal concentration solutions (Cd, Pb and Cu) were prepared and added as stock solutions of their salts (CdCl2*2.5 H2O, Pb(NO3)2*H2O and CuSO4*5 H2O). Results and Discussion The growth decreased gradually with the alga exposed to Cd at 0.05, 0.1, and 0.5 mg/L in comparison with the control whereas 1 mg/L Cd2+ had a clearly destructive effect. The growth was decreased with Pb at 15, 20 and 25 mg/L gradually, while at 30 mg/L the effect was more pronounced. When Cu was used, the growth was increased gradually at 0.5, 1 and 1.5 mg/L and vice versa at 2 mg/L. Conclusion There were differences in toxic effects of the metals with different metal as well as their concentrations and the time of exposure.     

Chemical contamination and sediment toxicity along the coast of Corsica

Trace metals (Cd, Pb, Cu, Cr, Ni, Co, Zn, Hg, As, Mn, Al, Fe, and Li) and organic compounds (PCBs, PAHs, lindanes, and DDT and its degradation products) were measured in coastal sediment samples from 27 sites in lagoons and along coastal areas of Corsica. An oyster embryo bioassay evaluated the toxicity of sediments from sites in three coastal lagoons (Urbino, Diane, and Biguglia) and the west coast of Cape Corsica. Despite contamination levels generally lower than those in other Mediterranean coastal areas, contamination is found in specific sites in Corsica and includes natural arsenic contamination on the east coast, insecticide pollution (persistent lindane and DDT) in many areas, both cadmium and lead contamination around Sagone, general contamination of both main harbours (Bastia and Ajaccio) and their surrounding areas, and asbestos mining residues in western Cape Corsica. Monitoring development of Crassostrea gigas embryos showed toxic effects at sites near a factory on Cape Corsica, with up to 100% mortality of larvae, and lower levels of toxicity at Sagone (44% mortality) and in the three coastal lagoons (up to 28% mortality). Results of this regional study show the need for further monitoring to understand the environmental issues facing the Corsican coast.     

Iron toxicity resistance strategies in tropical grasses: The role of apoplastic radicular barriers

The revegetation of mined areas poses a great challenge to the iron ore mining industry. The initial recovery process in degraded areas might rely on the use of Fe-resistant grasses. Tropical grasses, such as Paspalum densum and Echinochloa crus-galli, show different resistance strategies to iron toxicity; however, these mechanisms are poorly understood. The Fe-resistance mechanisms and direct iron toxicity as a function of root apex removal were investigated. To achieve this purpose, both grass species were grown for up to 480?hr in a nutrient solution containing 0.019 or 7?mmol/L Fe-EDTA after the root apices had been removed or maintained. Cultivation in the presence of excess iron-induced leaf bronzing and the formation of iron plaque on the root surfaces of both grass species, but was more significant on those plants whose root apex had been removed. Iron accumulation was higher in the roots, but reached phytotoxic levels in the aerial parts as well. It did not hinder the biosynthesis of chloroplastidic pigments. No significant changes in gas exchange and chlorophyll a fluorescence occurred in either grass when their roots were kept intact; the contrary was true for plants with excised root apices. In both studied grasses, the root apoplastic barriers had an important function in the restriction of iron translocation from the root to the aerial plant parts, especially in E. crus-galli. Root apex removal negatively influenced the iron toxicity resistance mechanisms (tolerance in P. densum and avoidance in E. crus-galli).