酸性淋溶对铅锌尾矿金属行为的影响及植物毒性

露天存放的铅锌尾矿受到自身酸化和酸雨的双重影响,从而加剧尾矿对环境的影响。因此,研究尾矿在酸性条件下的重金属行为及其植物毒性,对植物在铅锌尾矿地的自然定居有非常重要的意义。将铅锌尾矿砂装柱,用pH2～7溶液淋溶50天的结果表明,酸度的提高可以显著地增加尾矿砂中重金属（Pb、Zn、Cu和Cd）的溶出。而随着时间的延长,Zn的溶出量明显增高,Pb和Cu的溶出则逐渐降低。在pH值＜3时,Cd的溶出逐渐升高,pH值＞3时,Cd的溶出也呈下降趋势。酸度对重金属溶出的影响由大至小依次为Zn＞Cd＞Cu＞Pb。渗滤液对植物的毒性随着起始淋溶酸度的提高与时间的推移而加剧     

Euro Chlor Risk Assessment for the Marine Environment Osparcom Region: North Sea - Principles and Purposes -

A voluntary programme on risk assessment for chlorinated chemicals was initiated by Euro Chlor (the European Chlorine Producers Federation). The study was targeted on the marine environment, starting with the North Sea, and the methodology used was based on the European Union risk assessment principles. Details of the method used are described in this paper. A first set of five compounds is published in this special issue: chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, tetrachloroethylene.     

Household willingness to pay for stream restoration on private and public land: Evidence from the Baltimore metropolitan region

Stream restoration is one of the most widely used interventions to mitigate urban stormwater impacts and improve water quality. Government agencies have typically focused urban stream restoration efforts on public lands that they already own, even though a substantial portion of stream miles in highly urbanized areas occur on privately owned land. Yet, limited research exists to distinguish household willingness to pay (WTP) for stream restoration occurring on private versus public land. In this study, we use a choice experiment to analyze how household WTP for stream restoration attributes vary by land ownership and distance to the restoration project. Our empirical results indicate that streambank stabilization approaches have positive WTP estimates that are substantially larger in magnitude than those related to riparian vegetation management for clearing or planting trees. In general, estimated total household WTP for each of the four restoration design scenarios on public land is higher than when the same restoration design is located on private land. Nonetheless, estimated household WTP for each restoration design scenario on private land is substantial, retaining the majority of the value found on public land in all cases.     

Toxicity Testing of Leachate from Waste Landfills Using Medaka (Oryzias Latipes) for Monitoring Environmental Safety

To investigate the environmental safety of waste disposal landfill sites and of land reclaimed from such sites, we evaluated the toxicity of leachate from these sites by a combination of bioassays in the Japanese killifish medaka Oryzias latipes. We tested for lethal toxicity in adult and larval medaka and for hatching inhibition of embryos from eggs. As biochemical evidence of the effects of leachate exposure, CYP1A (EROD activity) and vitellogenin (Vtg) were induced. We also bioassayed water-treated leachate and downstream river water. Leachate solution was lethal to larval and adult medaka. Embryo hatchability was inhibited, and abnormal hatching, spinal deformity and anisophthalmia occurred in embryos exposed to leachate solution. CYP1A was induced by exposure to leachate solution diluted to 1.0%, and EROD activity was significantly higher than in control. Vtg and unknown proteins were induced in the sera of male medaka exposed to the diluted leachate solution. Conventional water treatments worked effectively to remove toxic compounds but did not work well to remove element ions, including heavy metals. Treated leachate produced neither lethal toxicity nor hatching abnormalities during the exposure period. Fish toxicity tests for leachate would be useful for monitoring the environmental safety of landfill sites.     

Relationships Between Toxicity and Concentrations of Chemical Contaminants in Sediments from Sydney Harbour, Australia, and Vicinity

Correlation analyses between measures of toxicity and concentrations of chemical contaminants were conducted for 103 surficial sediments from Sydney Harbour, Australia, and vicinity. Toxicity tests consisted of amphipod survival and reburial tests of whole sediments (Corophium colo), sea urchin fertilisation and larval development tests of pore waters (Heliocidaris tuberculata) and microbial bioluminescence (Microtox) tests of solvent extracts and pore waters. Toxicity in most tests correlated with concentrations of metallic contaminants, in particular, zinc, lead and copper. Organic contaminants did not correlate as significantly with toxicity. However, Heliocidaris tuberculata showed relationships with organochlorine compounds in samples with low to moderate metals contamination. Toxicity in the Microtox solvent extract test appeared to be primarily influenced by the presence of sulfur. This study has no precedent in Australia and the results support the validity of using local indigenous species in toxicity tests of field-collected sediments. This toxicity/chemistry dataset may be used in evaluations of sediment quality guidelines recently introduced to Australia.     

反硝化真菌-细菌优化组合及其脱氮能力研究

从多种真菌中筛选到3株脱氮活性较高的真菌,并将其与一株从武汉市郊新筛选分离到的具有较强脱氮能力的细菌HS-03进行混和培养,通过正交实验确立其最佳培养条件。正交实验方差分析表明:碳源、pH值和温度3个因素对脱氮率的影响都非常显著,菌种因素对脱氮率有一定影响。实验结果表明,真菌与细菌混合脱氮的最佳培养条件为:以琥珀酸钠为碳源,NaNO3为N源,C/N为10,pH=7.5,温度30℃。细菌HS-03和真菌Fusariumoxyspurum的组合优于其它组合。在最佳培养条件下,该组合能在21h内去除10mmolNO3-,优于相同条件下细菌HS-03或真菌F.oxyspurum的反硝化能力。     

钻井废液毒性检测与评价研究

以几种典型钻井液体系为研究对象,分别选用成熟可靠的检测方法对其生物毒性、化学毒性和重金属含量进行分析,结果表明:部分钻井废液具有一定生物和化学毒性,其中,磺化体系钻井液在生物毒性和化学毒性方面均超标,应重点加强管理;低密度无固相体系和磺化体系钻井液中Hg和Cr元素存在不同程度的超标。     

A field experiment with variable-suction multi-compartment samplers to measure the spatio-temporal distribution of solute leaching in an agricultural soil

Solutes spread out in time and space as they move downwards from the soil surface with infiltrating water. Solute monitoring in the field is often limited to observations of resident concentrations, while flux concentrations govern the movement of solutes in soils. A recently developed multi-compartment sampler is capable of measuring fluxes at a high spatial resolution with minimal disturbance of the local pressure head field. The objective of this paper is to use this sampler to quantify the spatial and temporal variation of solute leaching below the root zone in an agricultural field under natural rainfall in winter and spring. We placed two samplers at 31 and 25 cm depth in an agricultural field, leaving the soil above undisturbed. Each sampler contained 100 separate cells of 31 × 31 mm. Water fluxes were measured every 5 min for each cell. We monitored leaching of a chloride pulse under natural rainfall by frequently extracting the collected leachate while leaving the samplers buried in situ. This experiment was followed by a dye tracer experiment. This setting yielded information that widely surpassed the information that can be provided by separate anionic and dye tracer trials, and solute transport monitoring by coring or suction cups. The detailed information provided by the samplers showed that percolation at the sampling depth started much faster (approximately 3 h after the start of rainfall) in initially wet soil (pressure head above − 65 cm) than in drier soil (more than 14 h at pressure heads below − 80 cm). At any time, 25% of the drainage passed through 5–6% of the sampled area, reflecting the effect of heterogeneity on the flow paths. The amount of solute carried by individual cells varied over four orders of magnitude. The lateral concentration differences were limited though. This suggests a convective–dispersive regime despite the short vertical travel distance. On the other hand, the dilution index indicates a slight tendency towards stochastic–convective transport at this depth. There was no evidence in the observed drainage patterns and dye stained profiles of significant disturbance of the flow field by the samplers.     

Tissue accumulation of aluminium is not a predictor of toxicity in the freshwater snail, Lymnaea stagnalis

The amount of toxic metal accumulated by an organism is often taken as an indicator of potential toxicity. We investigated this relationship in the freshwater snail, Lymnaea stagnalis, exposed to 500 μg l⁻¹ Al over 30 days, either alone or in the presence of phosphate (500 μg l⁻¹ P) or a fulvic acid surrogate (FAS; 10 mg l⁻¹ C). Behavioural activity was assessed and tissue accumulation of Al quantified. Lability of Al within the water column was a good predictor of toxicity. FAS increased both Al lability and behavioural dysfunction, whereas phosphate reduced Al lability, and completely abolished Al-induced behavioural toxicity. Tissue accumulation of Al was not linked to toxicity. Higher levels of Al were accumulated in snails exposed to Al + P, compared to those exposed to Al alone, whereas FAS reduced Al accumulation. These findings demonstrate that the degree of tissue accumulation of a metal can be independent of toxicity.     

Effects of low concentrations of the phenylurea herbicide diuron on biofilm algae and bacteria

A system of recirculating channels was used in this study to examine the long-term effects (29 d) of environmentally realistic concentrations of the herbicide diuron (from 0.07 to 7 μg L⁻¹) on biofilm communities. The autotrophic activity of biofilms was affected by this herbicide, as reflected by a marked decrease in the photosynthetic efficiency. Diuron exposure also increased chlorophyll-a content and reduced the biovolume of diatom taxa at low concentrations. The effects on bacteria were also remarkable. Bacterial abundance was reduced after a week of exposure to the herbicide at a range of concentrations. Effects were on the number of live bacteria and on the increase in the leucine-aminopeptidase activity. It is suggested that inputs of herbicides to the river ecosystem at low concentrations may cause a chain of effects in the biofilm, which include inhibitory effects on algae but also indirect effects on the relationships between biofilm components.