基于环境学习曲线的中国省际COD排放及减排潜力分析

基于2008年COD排放量,对人均COD排放量和万元产值COD排放量的区域分布格局及其成因进行了定最分析;同时,基于1999-2008年cOD排放量和经济发展数据,建屯了31个省区万元产值COD排放堪随人均GDP变化的环境学习曲线,并以所建立的环境学习曲线为依据,分析了1999、2002、2005和2008年4个时段的减排潜力变化及COD减排潜力的空间分布.结果表明:经济发展水平越高的地区,万元产值COD排放的负荷越小,万元产值COD减排的潜力越小;反之,经济发展水平越低的地区,万元产值COD排放的负荷越大,万元产值COD减排的潜力越大.     

The role of electromagnetic potentials in the evolutionary dynamics of ecosystems

It is discussed that the electromagnetic potential can cause the emergence of the coherent structures that in view of their coherence, openness and non-linearity, are able to self-organize and form various hierarchical levels of ecosystems. In the meantime the electromagnetic potential is also the physical agent acting as a messenger in these coherent structures. So it plays the task of reducing the number of independent microstates of a coherent system, becoming a candidate for implementing the concept of negentropy. Electromagnetic potential is shown to be essential for the self-organization and the time evolution of ecosystems, providing the mechanism for their non-locality, complexity and self-consistency (self-maintaining).     

重庆某工业园土壤重金属污染特征、风险及源解析

以重庆市某工业园区表层土壤为研究对象,探讨了土壤重金属在不同季节的污染特征,利用污染指数法、健康风险模型和主成分/绝对主成分得分受体模型进行风险评价和源分析。结果表明:不同季节土壤样品间各重金属含量差异显著。35.5%的样品中汞含量超出土壤污染风险筛选值,其他元素未超标。与土壤背景值相比,各元素表现出不同程度的富集,汞超标约110~1300倍。内梅罗指数显示土壤整体和汞元素处于轻度污染及以下,其他元素为安全。潜在生态危害指数显示,土壤整体和汞属于极强污染,镉属于轻微~强污染,其他元素为轻微污染。土壤重金属总致癌风险为2.6×10^-7~1.0×10^-5,总非致癌风险熵均小于1,砷存在致癌风险,主要通过经口摄入暴露。秋季中,汞、六价铬、铅、镍、砷和铜来自工业源,镉主要来源于自然成因。春季中,镉和铅来自交通、冶金和燃煤等排放,镍、砷和铜源于冶炼和金属表面处理等排放,汞主要来自化工生产和燃料燃烧。交通运输、工业生产和燃料燃烧等污染的排放是土壤重金属的主要来源,今后应加强园区内汞、砷和镉的源头减排和治理。     

提金含氰废水中电沉积铜的热力学分析

从热力学角度,结合有关热力学原理,利用热力学数据,计算出电沉积铜在常温及非常温下的标准电极电位φ0T,同时分析了铜与锌共沉积的有关热力学条件,为处理含氰废液电沉积铜提供了理论依据。      

德阳市主要农作物生产潜力

本文在简述了农业生产潜力定量测度方法的基础上,计算和分析了德阳市主要作物生产潜力。得出光能利用率低是造成该区作物产量不高的主要原因,各种作物中水稻生产力、生产潜力最大,不同种植制度中水旱轮作生产力、生产潜力最大     

用图像识别方法确定福建地震发生的相对概率

在地震危险性分析中,潜在震源区地震活动性参数的确定是关键的一环。为了不低估大地震的影响,恰如基分地将地震年平均发生率分配到带内各个潜在震源之内,准确确定地震带内发生Mj档震级的地震落在第i 个潜在震源区的概率是关键的一步。本文采用图像识别方法确定地震发生的相对概率,可以较客观地反映地震的时、空不均匀性,准确地确定地震带内发生Mj档震级的地震落在第i个潜在震源区的概率。     

Parameters affecting the stability of the digestate from a two-stage anaerobic process treating the organic fraction of municipal solid waste

This paper focused on the factors affecting the respiration rate of the digestate taken from a continuous anaerobic two-stage process treating the organic fraction of municipal solid waste (OFMSW). The process involved a hydrolytic reactor (HR) that produced a leachate fed to a submerged anaerobic membrane bioreactor (SAMBR). It was found that a volatile solids (VS) removal in the range 40-75% and an operating temperature in the HR between 21 and 35 °C resulted in digestates with similar respiration rates, with all digestates requiring 17 days of aeration before satisfying the British Standard Institution stability threshold of 16 mg CO₂ g VS⁻¹ day⁻¹. Sanitization of the digestate at 65 °C for 7 days allowed a mature digestate to be obtained. At 4 g VS L⁻¹ d⁻¹ and Solid Retention Times (SRT) greater than 70 days, all the digestates emitted CO₂ at a rate lower than 25 mg CO₂ g VS⁻¹ d⁻¹ after 3 days of aeration, while at SRT lower than 20 days all the digestates displayed a respiration rate greater than 25 mg CO₂ g VS⁻¹ d⁻¹. The compliance criteria for Class I digestate set by the European Commission (EC) and British Standard Institution (BSI) could not be met because of nickel and chromium contamination, which was probably due to attrition of the stainless steel stirrer in the HR.     

Relationship of surface changes to metal leaching from tungsten composite shot exposed to three different soil types

Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten-nickel-iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite and soil. Leachate, runoff, and soil samples were collected from the lysimeters and analyzed for metal content. The shots were analyzed using scanning electron microscopy (SEM) to evaluate surface changes. SEM results indicated that a soil’s particle size distribution initially affected the amount of metal that was sheared from the surface of the fired W-composite shots. Shearing was greatest in soils with larger soil particles (sand and gravel); shearing was least in soils composed of small soil particles (fines). Increased metallic shearing from the shot’s surface was associated with increased W dissolution, compared to controls, following a simulated 1 year soil aging.     

Performance evaluation of the UV/H2O2 process on selected nitrogenous organic compounds: reductions of organic contents vs. corresponding C-, N-DBPs formations

The presence of various organic contaminants in water sources is of concern due to their direct threats to human health and potential to react with disinfectants to form carcinogenic byproducts including trihalomethanes, haloacetic acids and nitrosamines in finished water. This study applied both medium-pressure and low-pressure ultraviolet light coupled with hydrogen peroxide (UV/H₂O₂) to evaluate its efficacy for degradation of selected nitrogenous organic compounds and corresponding disinfection byproduct (DBP) formation. Six organic compounds were chosen as target precursors based on their nitrogen contents and molecular structures. The results showed that higher oxidation capacity resulted in better reduction of organic matters and DBP formation potentials (DBPFPs). However, insufficient contact time and oxidant doses could lead to a rise of DBPFPs in the early stages of UV/H₂O₂ reactions. A greater percentage removal was achieved for organic carbon than organic nitrogen after UV/H₂O₂ treatment, especially for compounds with complicated structure such as diltiazem. During the UV/H₂O₂ treatment, the intermediate products include tertiary amine, dimethyl amine (DMA) or DMA-like structures, which are N-nitrosodimethylamine (NDMA) precursors after chlorination or chloramination. Furthermore, it was observed that using dissolved organic nitrogen and DMA to predict NDMAFP could lead to biased conclusions because of the complex nature of nitrogenous matters in aqueous environments.     

Mitigation Strategy to Contain Methane Emission from Rice-Fields

Methane is primarily a biogenic gas, which is implicated in global climate change. Among all the sources of methane emission, paddy fields form the most dominant source. An experiment was conducted with a common paddy crop (Oryza sativa var. Vishnuparag) by amending the soils with different organic manures and biofertilizers with a view to find out an inexpensive strategy to mitigate methane emission from the rice-fields. The results revealed that there was a seasonal change in the CH₄ flux, registering a peak at heading stage in all treatments. The application of rice straw before flooding and the biofertilizer after flooding enhances CH₄ efflux from the rice-fields significantly, while composts of cowdung and leaves did not stimulate CH₄ production and, rather, decreased CH₄ fluxes. As soil pH and temperature were optimum for methanogenesis, it was likely that the organic C and the redox potential mainly modulated methane production and its emission through rice plants.