生物质燃烧颗粒物的定量分析和化学形态

用电子探针技术开展单个含钾颗粒物的分析表征 .第一种方法用蒙特卡洛方法模拟电子束与样品复杂的相互作用 ,对于KCl晶粒取得的计算结果与理论值一致 .K/Cl比的均值为 0 996 ,标准偏差为 0 0 1 2 .由于晶形不规则和热稳定性差 ,K2 SO4 和KHSO4 的结果没有达到KCl的准确度 .其K/S比的均值和标准偏差分别为 1 90 5±0 0 1 3和 1 0 1 4± 0 0 72 .第二种方法用回归分析方法处理了同一种类若干数目的颗粒物分析数据 .直接用同种类标准颗粒物的分析结果校准 ,进行定量分析和化学形态识别 .研究结果表明 ,非洲草原大火燃烧排放时 ,含钾颗粒经历了逐步酸化的过程 .在排放时主要以KCl形态存在 ,少量是K2 SO4 和复盐 .在大气传输过程中逐渐酸化 ,主要转变成KHSO4 .少量停空时间长的颗粒则继续酸化 ,成为高度富硫的颗粒 .     

Black carbon: the reverse of its dark side

The emission of black carbon is known to cause major environmental problems. Black carbon particles contribute to global warming, carry carcinogenic compounds and cause serious health risks. Here, we show another side of the coin. We review evidence that black carbon may strongly reduce the risk posed by organic contaminants in sediments and soils. Extremely efficient sorption to black carbon pulls highly toxic polycyclic aromatic hydrocarbons, polychlorinated biphenyls, dioxins, polybrominated diphenylethers and pesticides into sediments and soils. This increased sorption is general, but strongest for planar (most toxic) compounds at environmentally relevant, low aqueous concentrations. Black carbon generally comprises about 9% of total organic carbon in aquatic sediments (median value of 300 sediments), and then may reduce uptake in organisms by up to two orders of magnitude. This implies that current environmental risk assessment systems for these contaminants may be unnecessarily safe.     

Chronic effects of vapour phase di-n-butyl phthalate (DBP) on six plant species

A fumigation experiment was performed in which six plant species representing the European flora were exposed to a range of DBP concentrations. Controlled amounts of DBP-saturated air were injected into the ingoing air-streams of plant fumigation chambers, maintaining constant concentrations there for a period of up to 76 days. The target concentrations were a control, 0.8, 1.5, 3.5, and 10.0 microg m(-3). The variation in sensitivity between plant species to atmospheric DBP was quantified on the basis of whole plant biomass in order to derive no-observed-effect-concentrations (NOECs). Significant dose-response relationships, based on realised concentrations, were thus derived using non-linear regression, resulting in NOECs of 0.51 microg m(-3) for Trifolium repens, 0.96 microg m(-3) for Brassica campestris, 1.87 microg m(-3) for Phaseolus vulgaris and 2.21 microg m(-3) for Plantago major. A significant effect was also observed for Holcus lanatus at 12.4 microg m(-3) DBP, but due to the variation at lower levels of DBP exposure, no dose-response relationship could be derived. No significant effect on growth of current year needles in Picea abies was observed, even at the highest level of DBP, 13.7 microg m(-3). Based on statistical extrapolation according to Aldenberg and Slob [Ecotox. Environ. Safety, 25 (1993) 48], an overall predicted no-effect concentration (PNEC) for the plant-atmosphere compartment of 0.33 microg m(-3) DBP was calculated. The PNEC was calculated using the mean and standard deviation of the NOEC for four of the tested species and an extrapolation factor. In addition to changes in leaf colour, leaf crinkling and growth reduction, a number of not quantified observations are described, indicating that DBP affects the physiology as well as the morphology of these species.     

Direct VUV photolysis of chlorinated methanes and their mixtures in a nitrogen stream

The gas-phase decomposition of CCl(4), CHCl(3) and CH(2)Cl(2) and their binary mixtures was studied in a flow-type reactor in a nitrogen gas stream, using a low-pressure mercury vapour lamp covered with a high-purity silica quartz sleeve. The 184.9 nm vacuum-ultraviolet (VUV) light emitted is able to rupture the C-Cl bond in these target substances. For H-containing compounds, the decomposition takes place not only by direct photolysis, but also by H abstraction by .Cl formed during the direct photolysis of the target substances. The relative contributions of direct photolysis and .Cl-sensitized reactions to the decomposition were estimated at different initial concentrations. The addition of CCl(4) to CHCl(3) or CH(2)Cl(2) increased their decomposition rates via increase of the .Cl concentration, whereas the addition of CH(2)Cl(2) to CHCl(3) decreased its degradation rate, suggesting that CH(2)Cl(2) acts as a .Cl radical scavenger. The variation of the product distribution confirms the effect of the composition of the irradiated gas mixtures on the relative contributions of .Cl-sensitized reactions and direct photolysis.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

Development and applications of functional gene microarrays in the analysis of the functional diversity, composition, and structure of microbial communities

Functional gene arrays (FGAs) are a special type of microarrays containing probes for key genes involved in microbial functional processes, such as biogeochemical cycling of carbon, nitrogen, sulfur, phosphorus, and metals, biodegradation of environmental contaminants, energy processing, and stress responses. GeoChips are considered as the most comprehensive FGAs. Experimentally established probe design criteria and a computational pipeline integrating sequence retrieval, probe design and verification, array construction, data analysis, and automatic update are used to develop the GeoChip technology. GeoChip has been systematically evaluated and demonstrated to be a powerful tool for rapid, specific, sensitive, and quantitative analysis of microbial communities in a high-throughput manner. Several generations of GeoChip have been developed and applied to investigate the functional diversity, composition, structure, function, and dynamics of a variety of microbial communities from different habitats, such as water, soil, marine, bioreactor, human microbiome, and extreme ecosystems. GeoChip is able to address fundamental questions related to global change, bioenergy, bioremediation, agricultural operation, land use, human health, environmental restoration, and ecological theories and to link the microbial community structure to environmental factors and ecosystem functioning.     

An agenda for assessing and improving conservation impacts of sustainability standards in tropical agriculture

Sustainability standards and certification serve to differentiate and provide market recognition to goods produced in accordance with social and environmental good practices, typically including practices to protect biodiversity. Such standards have seen rapid growth, including in tropical agricultural commodities such as cocoa, coffee, palm oil, soybeans, and tea. Given the role of sustainability standards in influencing land use in hotspots of biodiversity, deforestation, and agricultural intensification, much could be gained from efforts to evaluate and increase the conservation payoff of these schemes. To this end, we devised a systematic approach for monitoring and evaluating the conservation impacts of agricultural sustainability standards and for using the resulting evidence to improve the effectiveness of such standards over time. The approach is oriented around a set of hypotheses and corresponding research questions about how sustainability standards are predicted to deliver conservation benefits. These questions are addressed through data from multiple sources, including basic common information from certification audits; field monitoring of environmental outcomes at a sample of certified sites; and rigorous impact assessment research based on experimental or quasi‐experimental methods. Integration of these sources can generate time‐series data that are comparable across sites and regions and provide detailed portraits of the effects of sustainability standards. To implement this approach, we propose new collaborations between the conservation research community and the sustainability standards community to develop common indicators and monitoring protocols, foster data sharing and synthesis, and link research and practice more effectively. As the role of sustainability standards in tropical land‐use governance continues to evolve, robust evidence on the factors contributing to effectiveness can help to ensure that such standards are designed and implemented to maximize benefits for biodiversity conservation.     

Physicochemical characterization of industrial effluents and their effect on fish survival.

Water samples taken from selected industrial drainages and receiving streams in and around Islamabad, Pakistan, during the summers of 1987 to 1990 showed disturbances in pH and low oxygen levels. Selected metals (Fe, Pb, Zn, Cd, Cu, Ni, Hg) were higher in all effluents than in receiving waters. Static bioassays of the undiluted industrial effluents from three sites caused 100% mortality in carp during the first 24 hrs. Fishes also suffered 30 to 60% mortality when exposed to other undiluted industrial effluents and some mortality when industrial effluents were diluted by 50%.     

CALIBRATION AND APPLICATION OF QUAL-II TO THE LOWER WINOOSKI RIVER1

ABSTRACT: A modified version of the U.S. Environmental Protection Agency's QUAL-II water quality simulation model is calibrated and applied to the Lower Winooski River, Vermont. The river flows through the metropolitan Burlington area and is impacted by several industrial and municipal point sources and by operation of hydropower facilities. Several structural modifications are made in the model to improve water quality simulations in rivers impacted by algal growth; these include the addition of organic nitrogen and organic phosphorus compartments and provision for algal uptake of ammonia and/or nitrate nitrogen. The model is interfaced with statistical programs which facilitate tabulation, display, and analysis of observed and predicted concentrations. The model is calibrated and tested against data from two intensive water quality surveys. Applications demonstrate the factors controlling water quality and sensitivities to point source waste management strategies and flow, as influenced by hydropower operations.