纳米零价铁的微生物毒性效应研究进展

纳米零价铁(nanoscale zero-valent iron,NZVI)是一种新型的地下水修复材料,NZVI的生物安全性研究已经引起了世界各国学者的广泛关注。本文综述了国内外有关NZVI微生物毒性的研究成果,重点介绍了NZVI对微生物的毒性效应及致毒机理,归纳总结了影响NZVI颗粒毒性效应的各种因素,并对未来NZVI材料毒性研究的发展方向进行了展望,以期为NZVI的生物安全性研究提供参考。     

Modeling time-dependent toxicity to aquatic organisms from pulsed exposure of PAHs in urban road runoff

Understanding of the magnitude of urban runoff toxicity to aquatic organisms is important for effective management of runoff quality. In this paper, the aquatic toxicity of polycyclic aromatic hydrocarbons (PAHs) in urban road runoff was evaluated through a damage assessment model. Mortality probability of the organisms representative in aquatic environment was calculated using the monitored PAHs concentration in road runoff. The result showed that the toxicity of runoff in spring was higher than those in summer. Analysis of the time-dependent toxicity of series of runoff water samples illustrated that the toxicity of runoff water in the final phase of a runoff event may be as high as those in the initial phase. Therefore, the storm runoff treatment systems or strategies designed for capture and treatment of the initial portion of runoff may be inappropriate for control of runoff toxicity.     

Arsenite toxicity and uptake rate of rice (Oryza sativa L.) in vivo

Toxicity threshold of arsenite on intact rice seedlings was determined and arsenite uptake characteristics were investigated using non-toxic concentrations of arsenite.The arsenite toxicity threshold was 2.4 μM arsenite which reduced growth by 10% (EC₁₀). The two highest arsenite levels induced wilting of seedlings and reduced both, transpiration rate and net photosynthetic rate. Arsenic content in plant tissue increased up to 10.7 μM arsenite and then declined with increasing arsenite concentration in the treatment solution. The contents of Si, P, K, and of micronutrients Cu, Fe, Mn and Zn in shoot d.m. were reduced by arsenite levels ≥ 5.3 μM. In the non-toxic range, arsenite uptake rate was linearly related to arsenite concentration.High arsenite levels reduced growth without being taken up which might be due to increasing binding of arsenite to proteins at the outer side of the plasmalemma.     

A comparative study on the uptake of polycyclic aromatic hydrocarbons by Anodonta californiensis

Uptake of polycyclic aromatic hydrocarbons (PAHs) by the freshwater bivalve mollusc Anodonta californiensis was examined in the presence and absence of surfactant in order to gain further insight into mixture toxicity and to predict whether certain mixtures have negative and/or positive effects on aquatic organisms. In the presence of surfactant, the uptake of anthracene or chrysene was higher than that of naphthalene, given the same concentration in the solution. In the absence of surfactant, the trend was similar, but the uptakes were increased by approximately 100% compared to those in the presence of surfactant. On the uptake of naphthalene, the presence of anthracene showed only minor influence. The uptake of anthracene was affected by both naphthalene and chrysene. The uptake of chrysene was influenced by neither naphthalene nor anthracene. There was no observable displacement of divalent cations from the surface of the gill membrane by any of the PAHs studied.     

A novel method dependent only on the mixture information (MIM) for evaluating the toxicity of mixture

Compound contamination and toxicity interaction necessitate the development of models that have an insight into the combined toxicity of chemicals. In this paper, a novel and simple model dependent only on the mixture information (MIM), was developed. Firstly, the concentration-response data of seven groups of binary and multi-component (pseudo-binary) mixtures with different mixture ratios to Vibrio qinghaiensis sp.-Q67 were determined using the microplate toxicity analysis. Then, a desirable non-linear function was selected to fit the data. It was found that there are good linear correlations between the location parameter (α) and mixture ratio (p) of a component and between the steepness (β) and p. Based on the correlations, a mixture toxicity model independent of pure component toxicity profiles was built. The model can be used to accurately estimate the toxicities of the seven groups of mixtures, which greatly simplified the predictive procedure of the combined toxicity.     

Differences in response of two model estuarine crustaceans after lethal and sublethal exposures to chlorpyrifos

This study assessed the in vitro and in vivo effects of an acetylcholinesterase enzyme inhibitor (chlorpyrifos) in two estuarine crustaceans: grass shrimp (Palaemonetes pugio) and mysid (Americamysis bahia). The differences in response were quantified after lethal and sublethal exposures to chlorpyrifos and in vitro assays with chlorpyrifos-oxon. Results from the in vitro experiments indicated that the target enzyme, acetylcholinesterase (AChE), in the two species was similar in sensitivity to chlorpyrifos inhibition with IC50s of 0.98 nM and 0.89 nM for grass shrimp and mysids, respectively. In vivo experiments showed that mysids were significantly more sensitive to chlorpyrifos-induced AChE inhibition after 24 h of exposure. The in vivo EC50s for AChE inhibition were 1.23 μg L^?1 for grass shrimp and 0.027 μg L^?1 for mysids.

Median lethal concentrations (24h LC50 values) were 1.06 μg L^?1 for grass shrimp and 0.068 μg L^?1 for mysids. The results suggest that differences in the response of these two crustaceans are likely related to differences in uptake and metabolism rather than target site sensitivity.     

Developmental toxicity of cypermethrin in embryo-larval stages of zebrafish

Cypermethrin, a type II pyrethroid insecticide, is widely used throughout the world in agriculture, forestry, horticulture and homes. Though the neurotoxicity of cypermethrin has been thoroughly studied in adult rodents, little is so far available regarding the developmental toxicity of cypermethrin to fish in early life stages. To explore the potential developmental toxicity of cypermethrin, 4-h post-fertilization (hpf) zebrafish embryos were exposed to various concentrations of cypermethrin (0, 25, 50, 100, 200 and 400 μg L⁻¹) until 96 h. Among a suite of morphological abnormalities, the unique phenotype curvature was observed at concentrations as low as 25 μg L⁻¹. Studies revealed that 400 μg L⁻¹ cypermethrin significantly increased malondialdehyde production. In addition, activity of antioxidative enzymes including superoxide dismutase and catalase were significantly induced in zebrafish larvae in a concentration-dependent manner. To further investigate the toxic effects of cypermethrin on fish, acridine orange (AO) staining was performed at 400 μg L⁻¹ cypermethrin and the result showed notable signs of apoptosis mainly in the nervous system. Cypermethrin also down-regulated ogg1 and increased p53 gene expression as well as the caspase-3 activity. Our results demonstrate that cypermethrin was able to induce oxidative stress and produce apoptosis through the involvement of caspases in zebrafish embryos. In this study, we investigated the developmental toxicity of cypermethrin using zebrafish embryos, which could be helpful in fully understanding the potential mechanisms of cypermethrin exposure during embryogenesis and also suggested that zebrafish could serve as an ideal model for studying developmental toxicity of environmental contaminants.     

Embryo toxicity of pesticides and heavy metals to the ramshorn snail, Marisa cornuarietis (Prosobranchia)

An invertebrate embryo toxicity test with the ampullariid snail, Marisa cornuarietis, to assess the toxicity of pesticides and heavy metals recently was established. Snail embryos were treated with atrazine (100, 1000, 10 000, and 30 000 μg/L), imidacloprid (10 000, 25 000, and 50 000 μg/L), Ni²⁺ (0.1, 1, 10, and 100 μg/L) or Zn²⁺ (100, 200, 500, 1000, 2000, and 5000 μg/L). The effect of these substances was examined by monitoring the following endpoints: mortality, formation of tentacles and eyes, heart rate, hatching, and weight after hatching. Effects in term of a significant delay on the formation of both tentacles and eyes were found after treatment with 100 μg/L Ni²⁺ or 200 μg/L Zn²⁺. The heart rate was shown to significantly decrease at 25 000 μg/L imidacloprid or 1000 μg/L Zn²⁺. At 100 μg/L atrazine, 10 μg/L Ni²⁺, or 1000 μg/L Zn²⁺ a significant delay in hatching became visible. No significant mortality was observed for the tested concentrations of atrazine, imidacloprid, or Ni²⁺, while 5000 μg/L Zn²⁺ resulted in 100% mortality after 10 d. The weight of freshly hatched individuals remained unaffected in all treatments. On the basis of the lowest observed effect concentrations (LOECs) recorded, we could show the M. cornuarietis embryo toxicity test (MariETT) to react up to three orders of magnitude more sensitive (for metals) and at least one order of magnitude more sensitive (for the tested organics) than the established Danio rerio embryo test.     

Losses to the environment from the multilevel cycle of anthropogenic lead

As a component of a multi-level study of the anthropogenic lead cycle for year 2000 (52 countries, 8 regions, and the planet), we have estimated the lead flows in seven emission streams: tailings, slag, fabrication and manufacturing, dissipation from use, hibernation, landfilling, and dispersion following product discard. For every 1 kg of lead put into end use, 0.5 kg is lost to the environment, largely due to landfilling and dissipation from use. From the standpoint of the receiving media, 1/3 of the losses are to uncontained solids on land and 48% of the losses are to containment facilities on land. On a country basis, the largest losses occur in the United States and China, which between them are responsible for about 32% of total global lead losses. On a per capita basis, the highest lead losses occurred in the United Kingdom, Belgium-Luxembourg, and Ireland.     

水体沉积物毒性鉴别与评价研究进展

综述了水体沉积物毒性鉴别与评价的主流方法以及研究进展,指出毒性测试和致毒因子鉴别方法是限制水体沉积物污染生态风险评价的关键因素,认为发展和应用以生物标记物和生物效应为导向,尤其是各种具有污染专一性指示作用的生物效应标志测试方法的建立和应用,并结合具有选择性的样品分级技术和先进的仪器进行定性定量分析,将是以生物效应为导向、以化学分析为基础的复杂水体沉积物毒性鉴别与评价的重要发展方向.