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671.
Xinying Li Quanyuan Chen Yasu Zhou Mark Tyrer Yang Yu 《Waste management (New York, N.Y.)》2014,34(12):2494-2504
The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR (27Al and 29Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals. At the addition of 20% silica fume, leaching concentrations for Cu, Pb and Zn of the hydrated paste cured for 7 days decreased from 0.32 mg/L to 0.05 mg/L, 40.99 mg/L to 4.40 mg/L, and 6.96 mg/L to 0.21 mg/L compared with the MSWI fly ash. After curing for 135 days, Cd and Pb in the leachates were not detected, while Cu and Zn concentrations decreased to 0.02 mg/L and 0.03 mg/L. The speciation of Pb and Cd by the modified version of the European Community Bureau of Reference (BCR) extractions showed that these metals converted into more stable state in hydrated pastes of MSWI fly ash in the presence of silica fume. Although exchangeable and weak-acid soluble fractions of Cu and Zn increased with hydration time, silica fume addition of 10% can satisfy the requirement of detoxification for heavy metals investigated in terms of the identification standard of hazardous waste of China. 相似文献
672.
Xiao-Zhang Yu Xue-Hong Zhang Wei Liu 《Environmental science and pollution research international》2014,21(2):1411-1417
Responses of free amino acids to botanical assimilation of free cyanide were investigated. Young rice seedlings (Oryza sativa L. cv. XZX 45) were grown in nutrient solution amended with free cyanide (KCN). Cyanide was analyzed in solution as well as in plant materials to estimate the phyto-assimilation potential. Free amino acids in different parts of plants were also measured to determine metabolic responses to KCN exposure. Phyto-assimilation of KCN was obvious, and the rates were positively correlated to the concentration supplied. Although changes in total amino acid content in plant materials were negligible during KCN metabolism (p?>?0.05), responses of different amino acids to KCN treatments were quite different. All treatments with KCN increased the content of proline (Pro) and isoleucine (Ile) in roots significantly compared with control (p?<?0.05), while changes of aspartic acid, lysine, and histidine in roots were more evident at higher KCN treatments (p?<?0.05). Results indicate that the content of Pro, Ile, and tyrosine showed pronounced increase in shoots of rice seedlings exposed to KCN at 1.44 mg CN/L or higher (p?<?0.05). Other amino acids slightly changed in all plant materials exposed to KCN (p?>?0.05). Results indicate that specific amino acids in rice seedlings showed positive response to non-toxic concentrations of exogenous KCN. These findings could provide additional insights into the inducible mechanisms underlying the involvement of amino acids in KCN metabolism. 相似文献
673.
Brian Eder Daiwen Kang Rohit Mathur Jon Pleim Shaocai Yu Tanya Otte George Pouliot 《Atmospheric environment (Oxford, England : 1994)》2009,43(14):2312-2320
This paper provides a performance evaluation of the real-time, CONUS-scale National Air Quality Forecast Capability (NAQFC) that supported, in part, its transition into operational status. This evaluation focuses primarily on discrete forecasts for the maximum 8-h O3 concentrations covering the 4-month period, June through September, 2007, using measurements obtained from EPA's AIRNow network. Results indicate that the 2007 NAQFC performed as well or better than previous configurations, despite the expansion of the forecast domain into the western half of the nation that is dominated by complex terrain. The mean, domain-wide, season-long correlation was 0.70. When examined over time, the domain-wide correlations exhibit a fairly consistent nature, with values exceeding 0.60 (0.70) over 90% (55%) of the days. The NAQFC systematically over-predicted the 8-h O3 concentrations, continuing a trend established by earlier NAQFC configurations, though to a lesser degree. The summer-long mean forecast value of 53.2 ppb was 4.2 ppb higher than the observed value, resulting in a domain-wide Normalized Mean Bias (NMB) of 8.7%. Most of the over-prediction is associated with observed concentrations less than 50 ppb. In fact the model tends to under-predict when concentrations exceed 70 ppb. As with the bias, the error associated with the latest configuration was also lower. The summer-long Root Mean Square Error of 13.0 ppb (Normalized Mean Error (NME) = 20.4%) represented marked improvements over earlier forecasts. Examination of the spatial distribution of both the NMB and NME reveals that the NAQFC was generally within 25% for the NME and 25% for the NMB over a majority of the domain. Several areas of poorer performance, where the NMB and NME often exceed 25% and in some cases 50%, were noted. These areas include southern California, where the NAQFC tended to under-predict concentrations (especially on weekends) and the southeast Atlantic and Gulf coasts regions, where the model over-predicted. Subsequent analysis revealed that the incorrect temporal allocation of precursor emissions was likely the source of the under-prediction in southern California, while inaccurate simulation of PBL heights likely contributed to the over-prediction in the coastal regions. 相似文献
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676.
Advancement of renewables in Bangladesh and Thailand: Policy intervention and institutional settings
This article reviews and analyses the advancement of renewable sources of energy in Bangladesh and Thailand in terms of policy intervention and institutional settings. Since renewable forms of energy emit far smaller amounts of greenhouse gas compared with fossil fuels, their use should mitigate climate change impacts while contributing to the provision of energy services. The article turns first to a review of energy–environment trends and the potential for renewables in these two nations. It then discusses strategies for the advancement of renewables. It is argued that further significant efforts can be made towards the advancement of renewables in Bangladesh and Thailand. These two nations could also learn from the experience in industrialized nations and other developing nations with regard to requisite policy instruments and processes. A number of barriers remain to the advancement of renewables, especially in terms of policy arrangements, institutional settings, financing mechanisms and technologies. Resources, cooperation and learning are required in order to overcome such barriers and to foster the development of necessary policy measures. Implementation of the clean development mechanism (CDM) under the Kyoto Protocol, and replication and adaptation of effective strategies from other settings are possible avenues for this. 相似文献
677.
Jing Wu Shaw L. Yu Rui Zou 《Journal of the American Water Resources Association》2006,42(5):1193-1204
ABSTRACT: Watershed management strategies generally involve controlling nonpoint source pollution by implementing various best management practices (BMPs). Currently, stormwater management programs in most states use a performance‐based approach to implement onsite BMPs. This approach fails to link the onsite BMP performance directly to receiving water quality benefits, and it does not take into account the combined treatment effects of all the stormwater management practices within a watershed. To address these issues, this paper proposes a water quality‐based BMP planning approach for effective nonpoint source pollution control at a watershed scale. A coupled modeling system consisting of a watershed model (HSPF) and a receiving water quality model (CE‐QUAL‐W2) was developed to establish the linkage between BMP performance and receiving water quality targets. A Monte Carlo simulation approach was utilized to develop alternative BMP strategies at a watershed level. The developed methodology was applied to the Swift Creek Reservoir watershed in Virginia, and the results show that the proposed approach allows for the development of BMP strategies that lead to full compliance with water quality requirements. 相似文献
678.
用固体力学化学理论研究岩土的力学化学行为——以成都龙泉紫色土为例 总被引:1,自引:0,他引:1
根据固体力学化学理论 ,提出用化学动力学方法研究岩土破坏及滑坡形成的机理 ,并以成都龙泉紫色土为例研究了在力与水协同作用下易滑土层的力学化学行为。实验表明 ,土长期抗剪强度降低的幅度与溶液的pH值有关 ,土的溶解速度与易溶盐含量有关 ,且溶解曲线略呈“S”型。这初步证明了龙泉紫色土破坏的力学 化学效应及其可能存在的自催化趋势。通过实验了解了力与水协同作用导致土破坏的力学化学规律 ,并将定量求解滑面长期抗剪强度与反应机理研究结合起来 ,为定量评价地下水和应力对岩土破坏机理这一滑坡学关键问题打下基础。 相似文献
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680.
甲撑二苯基二异氰酸酯 (MDI)生产过程中涉及到了多种危险有害因素。笔者通过对国内现役MDI生产装置进行调研 ,同时结合国内外其他涉及光气生产厂家的情况 ,分析并指出了生产过程中可能出现的危险有害因素 ,从而提出了相应的对策措施 相似文献