锅炉废气流化床污泥干化塔的热力计算与分析

利用锅炉尾部废烟气(120～190℃)干化市政污泥,降低污泥含水率可达到后继合理利用。从三方面对污泥干化进行了分析:1)干燥后污泥含水率与污泥处理量关系;2)入口烟温、流量与污泥处理量关系;3)干燥后烟气相对湿度影响因素分析。结果表明:提高入口烟温、流量,污泥出口含水率都可以提高污泥处理量,高入口烟温、流量下,污泥处理量受含水率的影响更大;污泥出口含水率高时,入口烟温提高使污泥处理量提高增大显著;入口烟气流量愈高,入口烟温提高对污泥处理量的增加愈大。干燥后烟气相对湿度与入口烟温有关,干燥之后的烟气的相对湿度离饱和状态较远,此温度范围内的出口烟气湿度还有较大的余量。     

g 辐照预处理促进剩余污泥发酵产氢的研究

为降低能耗,提高辐照技术的经济性,探讨了在0~9.5kGy范围内,γ辐照剂量对生活污水处理厂二沉池剩余污泥中耗氢菌的抑制效果和对发酵产氢的影响,建立了描述发酵产氢过程及辐照影响的动力学模型.结果表明,γ辐照剂量从0增加至9.5kGy时,污泥溶解率从0增加至4%,上清液中可检测出一定的蛋白质和多糖等物质,其中蛋白质中的氮素占溶出总氮素的90%,表明较低剂量辐照即对污泥菌体造成较明显的破解,这可在一定程度上抑制无法形成芽孢的耗氢菌活性;与之相对应的是污泥发酵产氢能力的明显提升,以葡萄糖为底物(1.0g/L),在35℃和初始pH值为7.0时,当辐射剂量仅为0.5kGy时,累积产氢量即比未辐照时有70%的提升,进一步增加辐照剂量至5kGy,累计产氢量和产氢得率均继续增长且达到最大值,分别为240mL/g葡萄糖和1.93mLH2/mol葡萄糖(发酵液的污泥量达2.0g VSS/L);此后,污泥发酵产氢能力随辐射剂量的增加而降低.修正的Logistic模型能很好地描述本研究中累积产氢量随时间的变化规律,而修正的Han-Levenspiel模型能很好地描述辐照剂量对平均产氢速率的影响.     

Associations between soil lead concentrations and populations by race/ethnicity and income-to-poverty ratio in urban and rural areas

Lead (Pb) is a well-studied environmental contaminant that has many negative health effects, especially for children. Both racial/ethnic and income disparities have been documented with respect to exposure to Pb in soils. The objectives of this study were to assess whether soil Pb concentrations in rural and urban areas of South Carolina USA, previously identified as having clusters of intellectual disabilities (ID) in children, were positively associated with populations of minority and low-income individuals and children (≤6 years of age). Surface soils from two rural and two urban areas with identified clusters of ID were analyzed for Pb and concentrations were spatially interpolated using inverse distance weighted analysis. Population race/ethnicity and income-to-poverty ratio (ITPR) from United States Census 2000 block group data were aerially interpolated by block group within each area. Urban areas had significantly higher concentrations of Pb than rural areas. Significant positive associations between black, non-Hispanic Latino, individuals and children ≤6 years of age and mean estimated Pb concentrations were observed in both urban (r = 0.38, p = 0.0007) and rural (r = 0.53, p = 0.04) areas. Significant positive associations also were observed between individuals and children with an ITPR < 1.00 and Pb concentrations, though primarily in urban areas. Racial/ethnic minorities and low ITPR individuals, including children, may be at elevated risk for exposure to Pb in soils.     

Methodology for an urban ecological footprint to evaluate sustainable development in China

The ecological footprint (EF) is a method for measuring sustainable development through ecological impact. A methodology is presented for predicting urban ecological footprints. Urban energy use and natural resource consumption were analyzed to calculate an EF based on land type (arable, pasture, forest, fossil energy land, built-up area and water area) and consumption (food, housing, transportation, goods, services and waste). The result was then compared with the local ecological carrying capacity to develop criteria for sustainable ecological footprints. Case studies of four cities in China (Guangzhou, Ningbo, Suzhou and Yangzhou) illustrate the urban EF approach. The time series of EF in a case study of Guangzhou for 1991–2001 was analyzed and the consumption–land-use matrix of urban EF was established. The results show that the cities are ecologically unsustainable, with average ecological conflicts per capita of more than 2 ha. The urban EF method is useful to measure urban sustainable development and provides policy proposals for decision-making. However, the EF method still has limitations and weaknesses.     

Space-time stick-breaking processes for small area disease cluster estimation

We propose a space-time stick-breaking process for the disease cluster estimation. The dependencies for spatial and temporal effects are introduced by using space-time covariate dependent kernel stick-breaking processes. We compared this model with the space-time standard random effect model by checking each model’s ability in terms of cluster detection of various shapes and sizes. This comparison was made for simulated data where the true risks were known. For the simulated data, we have observed that space-time stick-breaking process performs better in detecting medium- and high-risk clusters. For the real data, county specific low birth weight incidences for the state of South Carolina for the years 1997–2007, we have illustrated how the proposed model can be used to find grouping of counties of higher incidence rate.     

我国生活垃圾焚烧二恶英污染现状及减排建议

生活垃圾焚烧的二恶英污染问题在我国已经引起全社会的广泛关注。在分析我国生活垃圾焚烧行业现状与发展趋势和我国部分焚烧厂二恶英排放情况的基础上,提出了我国生活垃圾焚烧二恶英污染防治和减排的建议。     

Effect of weathering on abundance and release of potentially toxic elements in soils developed on Lower Cambrian black shales, P. R. China

This paper examines the geochemical features of 8 soil profiles developed on metalliferous black shales distributed in the central parts of the South China black shale horizon. The concentrations of 21 trace elements and 8 major elements were determined using ICP-MS and XRF, respectively, and weathering intensity (W) was calculated according to a new technique recently proposed in the literature. The data showed that the black shale soils inherited a heterogeneous geochemical character from their parent materials. A partial least square regression model and EF_bedrock (enrichment factor normalized to underlying bedrock) indicated that W was not a major control in the redistribution of trace metals. Barium, Sn, Cu, V, and U tended to be leached in the upper soil horizons and trapped by Al and Fe oxides, whereas Sb, Cd, and Mo with negative EF values across the whole profiles may have been leached out during the first stage of pedogenesis (mainly weathering of black shale). Compared with the Chinese average soils, the soils were strongly enriched in the potentially toxic metals Mo, Cd, Sb, Sn, U, V, Cu, and Ba, among which the 5 first listed were enriched to the highest degrees. Elevated concentrations of these toxic metals can have a long-term negative effect on human health, in particular, the soils in mining areas dominated by strongly acidic conditions. As a whole, the black shale soils have much in common with acid sulfate soils. Therefore, black shale soils together with acid sulfate soils deserve more attention in the context of metal exposure and human health.     

腾冲热海高温酸性热泉类病毒颗粒的多样性

为了解云南腾冲热海高温酸性热泉中类病毒颗粒的多样性及特征,采用电子显微镜、双层平板及DNA限制性酶切分析等方法,从腾冲热海61~94℃酸性热泉富集液中分离纯化病毒颗粒,对病毒形态特征进行分析比较.结果显示:腾冲热海不同酸性热泉样品富集培养物中病毒DNA的限制性酶切图谱差异明显;病毒液中共观察到4种不同类型的病毒状颗粒,依据其形态特征,大致可以分为头尾型病毒、丝状病毒、球状病毒、纺锤型病毒;这些病毒形态与分离自美国、日本、冰岛等地的高温酸性热泉病毒形态基本相似,多数类似于硫化叶菌已发现的病毒,可见腾冲热海高温酸性热泉中类病毒颗粒具有一定的多样性.同时分离获得一株硫化叶菌病毒,呈纺锤形,一端有尾,纺锤形头部的大小为220 nm×80 nm,尾部的长度变化很大,从20~100 nm不等,平均长度为50 nm左右,病毒有囊膜,囊膜的厚度约为10~15 nm,该病毒的形态特征、形成抑菌斑的大小及宿主菌株的特性与分离自腾冲热海的第一株硫化叶菌病毒STSV1差异显著,可能为一株新的硫化叶菌病毒,故命名为STSV2(Sulfolobus tengchongensis spindle-shaped virus 2).     

准好氧填埋场垃圾样品中甲烷氧化菌的群落多样性分析

为了探讨准好氧垃圾填埋场中的甲烷氧化机理,本研究利用RealTime-PCR和PCR-DGGE技术对其中的甲烷氧化菌分别进行了定量分析和群落多样性分析。研究结果表明,PCR-DGGE技术可以用于垃圾样品中甲烷氧化菌的微生物多样性分析;在距导气管0、2.5、5.0、10.0和15.0 m处垃圾样品中甲烷氧化菌的数量分别为1.13×109、2.22×108、2.38×108、2.20×107和5.21×106g-1,呈现逐渐降低的趋势;垃圾样品中甲烷氧化菌的丰富度和香侬多样性指数依次为：0 m〉2.5 m〉5.0 m=10.0m〉15.0 m,此外,垃圾样品中甲烷氧化菌可归为：Methylocaldum（甲基暖菌属）、Methylobacterium（甲基杆菌属）和Methylocystis（甲基孢囊菌属）,且优势菌种为Type I型Methylocaldum。     

慈姑(Sagittaria trifolia)根系泌氧特征

借助高精度溶解氧微电极,研究了自然沉积物中慈姑(Sagittaria trifolia)根不同部位的泌氧能力差异以及光照对根系泌氧能力的影响。结果表明,慈姑根系不同部位的泌氧能力存在差异,光照和黑暗条件下根区氧气扩散层厚度由大到小依次为1/2根长(0.98、0.72 mm)、3/4根长(0.68、0.28 mm)、根尖(0.58、0.44 mm)和1/4根长(0.42、0.32 mm);光照条件下不同根长部位根表面溶解氧含量由大到小依次为1/2根长〔64.56%(以%空气饱和度计)〕、3/4根长(52.73%)、根尖(38.55%)和1/4根长(20.55%),这与根部泌氧屏障、通气组织发育程度和根组织呼吸代谢有关。无论有无光照,慈姑根均有泌氧产生,光照条件下根表面溶解氧含量和根区氧气扩散层厚度均高于黑暗条件;在光照和黑暗条件下1/2根长处根表面溶解氧含量均显著高于其他测定点(P<0.05);除1/2根长处以外的其他测定点,在光照条件下的根表面溶解氧含量差异显著(P<0.05),但在黑暗条件下趋于相同(P>0.05)。