额济纳天然胡杨林水分利用效率动态变化研究

黑河下游的额济纳绿洲是我国西北地区重要的生态屏障,也是当地人民赖以生存的自然资源,然而由于种种原因,这片绿洲正在衰败并且有消亡的危险.胡杨是典型的潜水旱中生植物,它虽然有较强的耐大气干旱、耐盐碱能力,其生长发育与水分条件的优劣有着十分密切的关系.本文通过研究额济纳天然胡杨的叶水势、蒸腾速率、光合速率的变化规律,综合分析其水分利用效率与叶水势的相关关系,了解胡杨树体内水分运移关系,为揭示胡杨生存现状和合理利用水资源提供理论依据,为合理保护额济纳绿洲胡杨林提供科学支持.     

流动电位法测定滤料表面的Zeta电位

滤料表面的ζ电位是评价滤料颗粒表面性质的重要指标之一,研究滤料表面的ζ电位对于提高过滤效率以及开发改性滤料是十分重要的.根据流动电位与ζ电位的关系自制了一套测定ζ电位的装置,经测定计算出了4种常用水处理滤料表面的ζ电位,结果表明:当滤料的粒径范围在0.45～0.9mm之间时,使用该装置测得的磁铁矿、无烟煤、核桃壳和陶粒表面ζ电位分别为-27.64mV、-6.54mV、-5.87mV、-2.30mV.电子能谱和红外光谱分析结果证明磁铁矿、无烟煤、核桃壳和陶粒滤料表面ζ电位的差异主要归因于其表面化学结构的不同.     

Potential toxic risk of heavy metals from sediment of the Pearl River in South China

Based on the monitoring of five heavy metal elements in the surface sediments of the Pearl River in South China, potential toxicity of the heavy metals was assessed using consensus-based sediment quality guidelines (SQGs) method and geo-accumulation (I_geo) index method. The monitoring results showed the heavy metal concentrations were significantly and positively correlated with each other, demonstrating a common trend in variation of concentration in the surface sediments. The assessment using the consensus-based SQGs method showed the potential toxicity of Cu was the highest, and Cd was the lowest. The evaluation based on mean probable effect concentration (PEC) quotient showed the region was seriously polluted with high toxicity heavy metals. Correlation analysis revealed a significant and positive correlation between the mean PEC quotient and the average of I_geo with a correlation coefficient of 0.926 (n = 23, P < 0.01). In conclusion, the consensus-based SQGs and mean PEC quotient are applicable to assess potential toxicity risks of heavy metals in freshwater sediments in the Pearl River.     

流域水环境优先控制污染物筛选方法研究

本方法借鉴国内外经验,采用美国环保局工业环境实验室提出的化合物的潜在危害指数来指示物质对环境的毒性,结合某流域丰、平、枯三个水期测定出的有机污染物的检出浓度和检出频次以及流域污染源的检出频次,利用分级、加权法对检出的化合物进行排序,遵循有源、可控的原则,筛选出某流域的优先控制污染物。所提出的方法具有合理性和可操作性。     

水热处理泔脚脱油与产物消化性能变化

水热预处理泔脚废物,测定生物化学甲烷势(BMP),研究废物脱油、水解和消化性能的变化.结果表明,预处理加速废物的溶解和有机物的水解.随着反应温度升高,产物pH 降低,SCOD 和VFA浓度显著升高.150℃、 60 min预处理后,可浮油含量增加并达到较好的分离效果,消化过程在4～6 d内完成,降解速率提高1倍.170℃预处理后4 d生物气产量最高,继续提高温度会降低产物甲烷势.能量衡算分析表明,优化预处理能耗合理.     

基于量子化学分析表面活性剂对不同煤种润湿机理的影响*

为研究不同类型表面活性剂对煤润湿性的调控机理,首先将所选煤样的润湿性与煤样成分进行关联分析,然后采用透过高度法实验及量子化学计算相结合的方法研究表面活性剂对煤样润湿性的影响效果及机理。结果表明:煤的润湿性与煤中固有水分、灰分呈正相关关系,与煤中固定碳呈负相关关系;所选取的4种表面活性剂的加入会降低褐煤的亲水性,而对长焰煤、焦煤和无烟煤亲水性有提升作用,并且十二烷基硫酸钠对于这3种煤样亲水性的提升作用最为明显;表面活性剂分子、水分子及煤分子的表面静电势分布共同决定了表面活性剂对煤浸润性的影响。     

Screening for a new Streptomyces strain capable of e cient keratin degradation

Keratinous wastes could be degraded by some microorganisms in nature. Native human foot skin （NHFS） was used as sole nitrogen source to screen microorganisms with keratin-degrading capability. From approximately 200 strains, a strain of Streptomyces sp. strain No. 16 was found to possess the strongest keratinolytic activity, and the total activity in the culture was 110 KU/ml with specific activity of 2870 KU/mg protein （KU： keratinase unit）. Substrate specificity test indicated that the crude keratinase could degrade keratin azure, human hair, cock feathers and collagen. The optimal pH of the crude keratinase ranged from 7.5 to 10 and the temperature ranged from 40℃ to 55℃. Metal chelating agent ethylenediamine tetraacetic acid obviously stimulated the keratinolytic activity but suppressed the proteolytic activity. To our knowledge, this is the first report on specific induction of keratinases by NHFS from an actinomycete. Moreover, excellent characteristics of its crude keratinase may lead to the potential application in waste treatment and recovery, poultry and leather industry, medicine, and cosmetic development.     

Effect of elevated tropospheric ozone on methane and nitrous oxide emission from rice soil in north India

Physiological changes in crop plants in response to the elevated tropospheric ozone (O₃) may alter N and C cycles in soil. This may also affect the atmosphere-biosphere exchange of radiatively important greenhouse gases (GHGs), e.g. methane (CH₄) and nitrous oxide (N₂O) from soil. A study was carried out during July to November of 2007 and 2008 in the experimental farm of Indian Agricultural Research Institute, New Delhi to assess the effects of elevated tropospheric ozone on methane and nitrous oxide emissions from rice (Oryza sativa L.) soil. Rice crop was grown in open top chambers (OTC) under elevated ozone (EO), non-filtered air (NF), charcoal filtered air (CF) and ambient air (AA). Seasonal mean concentrations of O₃ were 4.3 ± 0.9, 26.2 ± 1.9, 59.1 ± 4.2 and 27.5 ± 2.3 ppb during year 2007 and 5.9 ± 1.1, 37.2 ± 2.5, 69.7 ± 3.9 and 39.2 ± 1.8 ppb during year 2008 for treatments CF, NF, EO and AA, respectively. Cumulative seasonal CH₄ emission reduced by 29.7% and 40.4% under the elevated ozone (EO) compared to the non-filtered air (NF), whereas the emission increased by 21.5% and 16.7% in the charcoal filtered air (CF) in 2007 and 2008, respectively. Cumulative seasonal emission of N₂O ranged from 47.8 mg m⁻² in elevated ozone to 54.6 mg m⁻² in charcoal filtered air in 2007 and from 46.4 to 62.1 mg m⁻² in 2008. Elevated ozone reduced grain yield by 11.3% and 12.4% in 2007 and 2008, respectively. Global warming potential (GWP) per unit of rice yield was the least under elevated ozone levels. Dissolved organic C content of soil was lowest under the elevated ozone treatment. Decrease in availability of substrate i.e., dissolved organic C under elevated ozone resulted in a decline in GHG emissions. Filtration of ozone from ambient air increased grain yield and growth parameters of rice and emission of GHGs.     

Effects of waste recovery on carbon footprint: a case study of the Gulf of Bothnia steel and zinc industries

This article analyses the impact of waste recovery on climate change mitigation on a regional scale. We focus on the EU End of Waste (EoW) policy, which aims at reducing negative impacts on the environment through the minimization of generated waste. At the same time, the EU climate objectives set challenging goals for the industry to lower greenhouse gas emissions. We argue that the goals of these two policies are conflicting: under certain circumstances, the EoW will lead into increased greenhouse gas emissions because of a number of negative feedback effects that function on multiple spatial and temporal scales.To assess the effects of waste recovery on greenhouse gas emissions, we carry out a consequential life-cycle inventory on a proposed industrial ecosystem around the Gulf of Bothnia between Finland and Sweden. The system recovers currently unutilized steelmaking dust and slag from four steel mills in Finland and Sweden and converts them into iron and zinc raw materials in a novel rotary hearth furnace. The recovered iron is led back into the blast furnace of one of the steel mills and zinc is treated in an existing zinc plant. In the European scale, the model system is significant in size, serving thus as a model for integrated EoW and carbon footprint assessments in other similar cases within the EU.The analysis reveals the relative greenhouse gas emissions from raw material extraction and production, heat and power generation, transport and the production process itself, in comparison to the present system with limited material recovery. To test the model viability, we conduct a sensitivity analysis with respect to increasing energy and production capacity. Our analysis shows that from the point of view of a single operator, material recovery may bring noteworthy reductions in greenhouse gas emissions. If the scale of the assessment is expanded beyond the confines of a single plant, however, we find limited potential for reducing greenhouse gas emissions through further recovery of steelmaking residues. In conclusion, we provide policy recommendations with which the EoW paradigm can provide better support for climate change mitigation on a regional scale.     

Characterization of disinfection byproduct formation potential in 13 source waters in China

The formation potential of four trihalomethanes (THMFP) and seven haloacetic acids (HAA7FP) in 13 source waters taken from four major water basin areas in China was evaluated using the simulated distribution system (SDS) chlorination method. The specific ultraviolet absorbance (SUVA254: the ratio of UV254 to dissolved organic carbon (DOC)), which ranged between 0.9 and 5.0 L/(mg m), showed that the organic compounds in di erent source waters exhibited di erent reactivities with chlorine. The HAA7FP of source waters ranged from 20 to 448 g/L and the THMFP ranged from 29 to 259 g/L. The HAA7FP concentrations were higher than the THMFP concentrations in all but one of the samples. Therefore, the risks of haloacetic acids (HAAs) should be of concern in some source waters. TCM (chloroform) and BDCM (bromodichloromethane) were the major THM constituents, while TCAA (trichloroacetic acid) and DCAA (dichloroacetic acid) were the major HAA species. Br-THM (brominated THM species) were much higher than Br- HAA (brominated HAA species), and the formation of Br-DBP (Br-THM and Br-HAA) should be of concern when the bromide concentration is over 100 g/L.