阊江上游河道整治底质粒径变化对鱼类群落多样性的影响

河床基质为溪流鱼类的重要栖息地.为研究溪流河道整治后基质组成变化对鱼类群落结构产生的影响及其作用机制,在阊江上游选取急流浅滩与缓流浅滩两种典型溪流生境,对比分析了两种生境河道整治前后鱼类群落结构的变化及其主要原因.结果表明,采集鱼类数量由河道整治前的24种降低至整治后的17种,但前后不存在显著性差异(P＞0.05);鱼类群落优势种由河道整治前的5种降低至整治后的3种.河道整治前鱼类群落的Shannon-Weiner指数、Simpson指数、Margalef指数和Pielou均匀度指数分别为1.623～2.253,0.715～0.866,1.680～3.109和0.652～0.813;整治后分别为 1.120～1.679,0.528～0.724,1.444～2.695和0.508～0.722.除春季和秋季整治后的Margalef指数高于整治前,其余各季节,河道整治前的多样性和均匀性指数均要高于整治后(P＜0.05).主要原因在于河道整治后河床基质粒径及粒径多样性降低、流态减少等使生境异质性降低.因此,建议在河道整治过程中避免选择性清除大粒径基质及裁弯取直等,以维持河床基质的多样性,从而防止或降低施工带来的不利影响.     

废铅酸蓄电池铅膏铵法预脱硫过程的动力学分析

以废铅酸蓄电池中铅膏为研究对象,开展了用NH_4HCO_3为脱硫剂对铅膏进行脱硫转化的实验研究。通过分析反应过程中PbSO_4转化率随时间的变化关系,考察了搅拌速度、反应温度及NH_4HCO_3浓度对铅膏脱硫转化的影响;利用固液多相反应的收缩核模型,分析了反应的动力学过程,并计算了反应的表观活化能及表观反应级数。结果表明:在实验选取的条件范围内,提高反应温度、增大NH_4HCO_3浓度及加快搅拌速度均可以促进铅膏的脱硫转化;表观活化能为9.7 kJ·mol~(-1),表观反应级数为0.71,反应过程受内扩散步骤控制。研究结果可为铅膏铵法预脱硫技术能高效、低耗的应用提供参考。     

高氯酸盐还原颗粒污泥的快速培养及其特性分析

为实现高氯酸盐还原颗粒污泥的快速培养,以反硝化颗粒污泥为接种污泥,对高氯酸盐还原颗粒污泥的快速培养进行了研究。在降低进水硝酸盐(NO_3~-)浓度的同时,采用逐步升高进水高氯酸盐(ClO_4~-)浓度的方法,考察了高氯酸盐还原颗粒污泥培养过程中ClO_4~-的去除以及颗粒污泥的特性。结果表明:以反硝化颗粒污泥为接种污泥,经过50 d快速培养出高氯酸盐还原颗粒污泥,ClO_4~-去除速率达96%以上;其混合液悬浮固体浓度(MLSS)为50.68 g·L~(-1),混合液挥发性固体浓度(MLVSS)为40.58 g·L~(-1),主要粒径分布在0.60 mm和1.00～2.00 mm。NO_3~-浓度逐步降低的培养方式可缓解ClO_4~-对颗粒污泥中各类微生物的毒性,为高氯酸盐颗粒污泥的快速培养提供了新的方法,具有重要的理论和实践意义。     

金属粉尘湿法处理系统的设计和除尘效果分析

为改善金属抛光操作人员的工作环境、降低抛光金属粉尘的爆炸风险,设计一种金属粉尘湿法处理系统,并通过建立多相流动数值模型,探究其内部流场特征与金属粉尘运动规律,分析金属粉尘湿法处理系统的除尘效率。研究结果表明:大粒径的金属粉尘直接重力沉降至水槽中;小粒径(PM10)的金属粉尘易随气流进入风道,进而通过水雾脱除;采用洁净进气源,可以有效降低工人操作环境的粉尘浓度;增加细水雾,可以有效提高金属粉尘湿法处理系统的除尘效率,对PM10的除尘效率从30%提升至82%。     

不同模糊评价方法在水环境质量评价中的应用比较

近年来,运用模糊评价方法对水质和水体营养化程度进行评价逐渐受到重视。目前,对模糊评价方法的研究多集中在实测数据标准化、权重的确定和模糊模式识别模型研究几个方面。以滇池历年营养物质数据为实测数据,通过对几种实测数据标准化方法、权重确定方法和模糊模式识别方法的组合应用,获得水环境质量模糊评价最优组合方法。结果表明,在评价方法中,实测数据标准化方法采用线性内插法,权重的确定采用超标倍数法,模糊模式识别模型采用广义海明距离和加权海明距离法,即采用超标倍数法的广义海明距离和加权海明距离法能够更真实反映水环境质量的实际情况。     

贫营养异养硝化细菌的分离鉴定及硝化性能研究

从水库底泥中分离出1株贫营养异养硝化细菌,命名为菌株Y11。经菌株生理特性研究和16SrDNA测序,鉴定出菌株Y11属于假单胞菌属细菌(Pseudomonas sp.)。考察了温度、pH及C/N对菌株Y11的硝化性能影响,结果表明,菌株Y11进行硝化作用的最适温度为30℃,最适pH为中性,最适C/N为6.0,在该条件下进行4d的硝化反应,菌株Y11对氨氮去除率可达91.42%。     

Fe(Ⅱ)EDTA络合吸收-铁粉还原再生脱除NO性能

利用Fe(Ⅱ)EDTA络合吸收-铁粉间歇还原再生脱除NO并回收氨资源的方法,实验研究了铁粉还原再生Fe(Ⅱ)(NO)EDTA的过程及其影响因素。结果表明,以0.015 mol/L的Fe(Ⅱ)EDTA做吸收剂,在起始p H 5.5、温度323K条件下吸收400×10-6~500×10-6的NO,脱除率95%以上;铁粉还原再生Fe(Ⅱ)(NO)EDTA过程可用缩芯模型阐释;铁粉添加量与搅拌强度直接决定了铁粉质点数量,是影响反应的重要因素;实验中Fe(Ⅱ)(NO)EDTA络合液150 m L,氧气含量为5%时,搅拌速度900 r/min、粒径为0.12 mm的铁粉浓度5.3 g/L、温度353 K、p H=6为最适宜再生条件。     

电催化氧化处理除草剂异噁草酮废水的效能

为有效处理含异噁草酮除草剂废水,以Sb掺杂Ti／SnO2电极为阳极,不锈钢板为阴极,采用电催化氧化技术对异噁草酮废水进行降解,研究了不同影响因素对异噁草酮去除率的影响,并分析了异噁草酮的降解效果。结果表明,当异噁草酮初始浓度为100mg／L、电流密度为20mA／cm2、电解质投加量为0．10mol／L,反应120min后,异噁草酮去除率达到94％,此时TOC去除率为57．9％,能耗为25kWh／m2,且废水的可生化性能显著提高。     

Temperature-dependent sorption of polycyclic aromatic hydrocarbons on natural and treated sediments

In aqueous environment temperature is considered to play a significant role in the sorption process of polycyclic aromatic hydrocarbons (PAHs) and its influence on the sorption equilibrium is indicative of sorption energies and mechanisms. In this study, sorptions of five PAHs on three heterogeneous sorbents including one river sediment (YHR), one estuary sediment (YRD) and one treated sediment with organic matter removed (IM) were carried out at a range of temperature from 5 °C to 35 °C. Stronger sorptions were observed at lower temperatures, with the equilibrium sorption coefficient K_d increasing 2-5 times as the temperature decreases 30 °C. The increase of K_d value was attributed primarily to the change of PAH water solubility, which predicted 40-75% of the increase of K_d in the sorption process. To provide insight into the sorption mechanism, enthalpy change (ΔH_S) for the sorption process was calculated and the values were observed to be negative for all of the interactions, suggesting that the exothermal sorption of PAHs inversely dependents on temperature. Based on the values of ΔH_S, van der Waals forces were inferred as the main sorption mechanism for the PAHs, especially on the YHR sediment which contained more organic matter. For sorption of larger size PAHs on the sorbents with low organic matter, specific interactions were deduced to contribute to the overall sorption.     

Evaluating inter-continental transport of fine aerosols:(2) Global health impact

In this second of two companion papers, we quantify for the first time the global impact on premature mortality of the inter-continental transport of fine aerosols (including sulfate, black carbon, organic carbon, and mineral dust) using the global modeling results of (Liu et al., 2009). Our objective is to estimate the number of premature mortalities in each of ten selected continental regions resulting from fine aerosols transported from foreign regions in approximately year 2000. Our simulated annual mean population-weighted (P-W) concentrations of total PM2.5 (aerosols with diameter less than 2.5 μm) are highest in East Asia (EA, 30 μg m^?3) and lowest in Australia (3.6 μg m^?3). Dust is the dominant component of PM2.5 transported between continents. We estimate global annual premature mortalities (for adults age 30 and up) due to inter-continental transport of PM2.5 to be nearly 380 thousand (K) in 2000. Approximately half of these deaths occur in the Indian subcontinent (IN), mostly due to aerosols transported from Africa and the Middle East (ME). Approximately 90K deaths globally are associated with exposure to foreign (i.e., originating outside a receptor region) non-dust PM2.5. More than half of the premature mortalities associated with foreign non-dust aerosols are due to aerosols originating from Europe (20K), ME (18K) and EA (15K); and nearly 60% of the 90K deaths occur in EA (21K), IN (19K) and Southeast Asia (16K). The lower and higher bounds of our estimated 95% confidence interval (considering uncertainties from the concentration–response relationship and simulated aerosol concentrations) are 18% and 240% of the estimated deaths, respectively, and could be larger if additional uncertainties were quantified. We find that in 2000 nearly 6.6K premature deaths in North America (NA) were associated with foreign PM2.5 exposure (5.5K from dust PM2.5). NA is least impacted by foreign PM2.5 compared to receptors on the Eurasian continent. However, the number of premature mortalities associated with foreign aerosols in NA (mostly occurring in the U.S.) is comparable to the reduction in premature mortalities expected to result from tightening the U.S. 8-h O₃ standard from 0.08 ppmv to 0.075 ppmv. International efforts to reduce inter-continental transport of fine aerosol pollution would substantially benefit public health on the Eurasian continent and would also benefit public health in the United States.