基于气团老化程度对挥发性有机物分类改善PMF源解析效果

VOCs作为臭氧与二次有机气溶胶的关键前体物,其来源解析对臭氧和颗粒物的协同控制至关重要.但多数VOCs具有反应性,不能完全满足受体模式对污染源排放化学物质组成稳定的假设要求,导致受体模式解析结果不能精准反映实际源贡献.为解决因不同VOCs反应活性不同而导致的组分相对变化与模型假设不符的问题,引入VOCs老化程度来表征...     

Low-carbon transition of iron and steel industry in China: Carbon intensity, economic growth and policy intervention

As the biggest iron and steel producer in the world and one of the highest CO₂ emission sectors, China's iron and steel industry is undergoing a low-carbon transition accompanied by remarkable technological progress and investment adjustment, in response to the macroeconomic climate and policy intervention. Many drivers of the CO₂ emissions of the iron and steel industry have been explored, but the relationships between CO₂ abatement, investment and technological expenditure, and their connections with the economic growth and governmental policies in China, have not been conjointly and empirically examined. We proposed a concise conceptual model and an econometric model to investigate this crucial question. The results of regression, Granger causality test and impulse response analysis indicated that technological expenditure can significantly reduce CO₂ emissions, and that investment expansion showed a negative impact on CO₂ emission reduction. It was also argued with empirical evidence that a good economic situation favored CO₂ abatement in China's iron and steel industry, while achieving CO₂ emission reduction in this industrial sector did not necessarily threaten economic growth. This shed light on the dispute over balancing emission cutting and economic growth. Regarding the policy aspects, the year 2000 was found to be an important turning point for policy evolution and the development of the iron and steel industry in China. The subsequent command and control policies had a significant, positive effect on CO₂ abatement.     

Microbial reduction of uranium (VI) by Bacillus sp. dwc-2: A macroscopic and spectroscopic study

The microbial reduction of U(VI) by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES). Our studies indicated that approximately 16.0% of U(VI) at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter (NOM) played an important role in enhancing the bioreduction of U(VI) by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states (U(VI) and U(IV)) after bioreduction, which was subsequently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy (HRTEM) analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wall. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.     

太湖流域居民暴露于DDTs的健康风险评价

采用多介质环境数学模型,评价太湖流域居民暴露于DDTs的健康风险,分析风险来源、暴露介质及暴露途径,并结合蒙特卡罗方法分析研究过程中的不确定性. 结果表明,太湖流域居民中男性和女性对环境中DDTs的终身日平均暴露量分别为4.00×10－4～8.28×10－3和3.73×10－4～7.28×10－3 mg/(kg·d). 暴露途径中食物摄取是最主要途径,其次是吸入,皮肤暴露作用很小. 食物中贡献较大的为谷物、鱼类和肉类. 相应的男性和女性的健康风险度分别为0.114×10－6～2.366×10－6 和0.107×10－6～2.081×10－6 a－1,低于可接受健康风险度标准的累积概率分别为80.85%和86.05%.      

高浓度阿维菌素生产废水治理与资源回收技术研究

采用预处理一厌氧水解－二段接触氧化工艺处理阿维菌素废水，在厌氧段停留时间为１０ｈ，好氧段停留时间为６ｈ条件下，厌氧好氧段ＣＯＤ总去除率达９１％，     

Effect of organic matter on phosphorus recovery from sewage sludge subjected to microwave hybrid pretreatment

Microwave (MW) hybrid processes are able to disrupt the flocculent structure of complex waste activated sludge, and help promote the recovery of phosphorus as struvite. In this study, to optimize struvite yield, (1) the characteristics of matter released in MW-hybrid treatments were compared, including MW, MW-acid, MW-alkali, MW-H₂O₂, and MW-H₂O₂-alkali. The results showed that selective release of carbon, nitrogen, phosphorus, Ca^2 +, and Mg^2 + achieved by sludge pretreatment using MW-hybrid processes. MW-H₂O₂ is the recommended sludge pretreatment process for phosphorus recovery in the form of struvite. The ratio of Mg^2 +:NH₄⁺-N:PO₄^3 −-P was 1.2:2.9:1 in the supernatant. (2) To clarify the effects of organic matter on struvite recovery, the composition and molecular weight distribution of organic matters were analyzed. Low molecular weight COD was found to facilitate the removal rate of NH₄⁺-N and PO₄³-P via crystallization, and the amorphous struvite crystals (< 1 kDa) from the filtered solutions had high purity. Therefore, the present study reveals the necessity of taking into consideration the interference effect of high molecular weight organic matters during struvite crystallization from sewage sludge.     

互花米草入侵对长江口湿地土壤碳动态的影响

为了评价互花米草入侵对长江河口湿地土壤碳动态的影响,利用配对的试验设计在长江口崇明东滩湿地的高潮滩和低潮滩各设置1条入侵种互花米草与土著种的配对样线.结果表明,与土著植物相比,互花米草入侵显著增加了长江口湿地的植物碳库、土壤微生物碳、土壤总碳库和有机碳库,而对占土壤总碳库60%以上的无机碳库无显著影响,意味着互花米草入侵导致的土壤总碳库改变主要是通过增加土壤有机碳库来实现的.高潮滩互花米草和芦苇群落的年均土壤呼吸强度分别为（210.02±4.90）,（157.79±6.39）mg/（m²·h）;低潮滩互花米草和海三棱藨草群落年均土壤CO₂排放速率分别为（157.41±5.27）,（110.90±5.16）mg/（m²·h）,表明互花米草入侵显著增加长江口湿地的土壤呼吸.上述结果意味着互花米草入侵同时增加土壤碳输入和碳输出,但入侵也显著增加了土壤碳库表明入侵增加的土壤碳输入显著高于增加的土壤碳输出.本研究表明互花米草入侵可能会增强了长江河口湿地的土壤碳汇强度和固碳能力.但仍然需要长期系统的监测研究,以便全面定量评估互花米草入侵我国滨海湿地的综合生态影响.     

基于SVR的含缺陷管道剩余强度研究

针对采用标准预测含缺陷管道剩余强度误差较大这一问题,在Matlab中建立基于SVR的含缺陷管道剩余强度预测模型,并基于60组含缺陷管道爆破试验数据进行训练测试,以验证模型的实际性能.结果表明:SVR模型预测测试集结果的最小相对误差为0.55％,最大相对误差为10.35％,平均相对误差为2.63％,预测结果的R2高达0....     

硫酸盐还原过程中乙酸型代谢方式的形成及其稳定性

通过产酸脱硫反应器处理高浓度硫酸盐废水的连续流试验,考察了不同试验阶段硫酸盐去除率和产气量稳定期,液相末端产物中挥发酸组成的变化、乙酸的分布特征、微生物种群组成和种群间关系.试验结果表明,各试验阶段液相末端产物中乙酸的分布比例高达50%～82%,微生物群体呈现特定的乙酸型代谢方式.乙酸型代谢方式本质上是产酸相反应器处理硫酸盐废水过程中,硫酸盐还原菌(SRB)与产酸菌(AB)建立起生物链式协同代谢关系,并通过非完全氧化型方式分解有机物,从而在末端产物中积累大量乙酸.乙酸型代谢方式的形成取决于利用乙酸的硫酸盐还原菌(ASRB)的竞争能力和它对乙酸的利用能力.乙酸型代谢方式可以为后续产甲烷相反应器提供适宜的底物,对提高硫酸盐废水处理系统的效率和运行稳定性具有重要意义.     

弹性填料微孔曝气生物膜法修复污染水源除NH4+-N

采用弹性填料微孔曝气生物接触氧化法对受污染的水源进行修复除NH₄⁺-N效果研究.结果表明,在正常水温20℃～27℃条件下,当污染水源COD_Mn7～14mg/L,NH₄⁺-N 0.7～2.0mg/L和生物修复工艺运行参数HRT为1.4h,气:水=0.5:1,DO为7～9mg/L时,生物修复工艺可去除水源中的NH₄⁺-N为64%～95%;在较低水温7℃～12℃条件下,当污染水源COD_Mn6～11mg/L,NH₄⁺-N 1.2～8.0mg/L和生物修复工艺运行参数HRT为1.4h,气:水=0.5:1,DO为8～10mg/L时,生物修复工艺可去除水源中的NH₄⁺-N为40%～63%.