短程硝化过程中NO-2-N高效富集的工艺条件实验研究

针对厌氧氨氧化工艺需要提供充足的亚硝酸盐氮为电子受体的问题,利用培养基对SBR中具有一定短程硝化功能的污泥进行富集培养,得到氨氧化菌和亚硝酸盐氧化菌的数量之比为104︰1,并研究了工艺条件对短程硝化的影响,结果表明,适合氨氧化菌生长的最佳温度为30℃、pH为7.5、nHCO^-₃/nNH⁺₄-N值为1。以适合氨氧化菌生长的最佳环境条件优化SBR,在进水氨氮浓度为250 mg/L时,氨氮的转化率达到90％以上,亚硝酸盐氮积累率维持在85％以上,反应器中氨氧化菌与亚硝酸盐氧化菌的数量之比为10³∶1,亚硝酸盐的高效积累为厌氧氨氧化工艺处理高氨废水的过程提供了稳定的电子受体。     

TiO2光催化处理络合铜废水的实验研究

研究了以悬浮态TiO2为催化剂,在紫外光的作用下对络合铜废水进行光催化反应,分别考察了常温下TiO2投加量、反应时间、废水初始pH值、反应气氛等因素对处理效果的影响,并探讨了反应机理。结果表明:TiO2投加量为2 g/L,废水pH=4,300 W高压汞灯照射下,载入60 mL/min的空气反应40 min,120 mg/L EDTA络合铜废水的Cu(II)与COD的去除率达到最高,分别为96.56%和57.67%。     

Assessment of exposure to DDT and metabolites after indoor residual spraying through the analysis of thatch material from rural African dwellings

Introduction  

We report on the analysis of 4,4′-dichlorodiphenyltrichloroethane (4,4′-DDT) and its metabolites in thatch and branch samples constituting the wall materials of dwellings from South African subtropical areas. This approach was used to assess the exposure to DDT in the residents of the dwellings after indoor residual spraying (IRS) following recommended sanitation practices against malaria vectors.     

Bacterial community profiles from sediments of the Anacostia River using metabolic and molecular analyses

Background aim and scope  

Though the tidal Anacostia River, a highly polluted riverine system, has been well characterized with regard to contaminants, its overall resident bacterial populations have remained largely unknown. Improving the health of this system will rely upon enhanced understanding of the diversity and functions of these communities. Bacterial DNA was extracted from archived (AR, year 2000) and fresh sediments (RE, year 2006) collected from various locations within the Anacostia River. Using a combination of metabolic and molecular techniques, community snapshots of sediment bacterial diversity and activity were produced.     

Bio-Ethanol Production from Non-Food Parts of Cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz)

Global climate issues and a looming energy crisis put agriculture under pressure in Sub-Saharan Africa. Climate adaptation measures must entail sustainable development benefits, and growing crops for food as well as energy may be a solution, removing people from hunger and poverty without compromising the environment. The present study investigated the feasibility of using non-food parts of cassava for energy production and the promising results revealed that at least 28% of peels and stems comprise dry matter, and 10 g feedstock yields >8.5 g sugar, which in turn produced >60% ethanol, with pH ≈ 2.85, 74-84% light transmittance and a conductivity of 368 mV, indicating a potential use of cassava feedstock for ethanol production. Thus, harnessing cassava for food as well as ethanol production is deemed feasible. Such a system would, however, require supportive policies to acquire a balance between food security and fuel.     

改性酚醛基炭泡沫的表面结构及脱硫脱硝

采用前驱体改性的方法,以CuCl2、FeCl2和MgCl2为改性剂,制备出改性酚醛泡沫,经炭化/活化得到改性酚醛基炭泡沫。研究了不同金属对酚醛基炭泡沫表面物理与化学特性的影响,并进行同时脱硫脱硝实验研究。通过研究发现,添加CuCl2的样品比添加FeCl2、MgCl2的样品的中孔孔容大接近10倍;比表面积和孔容是CFCu>CF0>CFFe>CFMg;金属改性剂主要以金属和金属氧化物的形式存在于酚醛基炭泡沫中,而表面其他官能团大体结构不变。经CuCl2、FeCl2和MgCl2改性后,脱硫效率分别提高了39%、11%和13%,脱硝效率分别提高了19%、10%和4%,其中以CuCl2改性的酚醛基炭泡沫的效率最高。     

Challenges in assessing the toxic effects of polycyclic aromatic hydrocarbons to marine organisms: a case study on the acute toxicity of pyrene to the European seabass (Dicentrarchus labrax L.)

The acute toxicity (96 h) of pyrene (PY) to European seabass (Dicentrachus labrax) juveniles assessed in a semi-static bioassay (SSB) with medium renewal at each 12 h, and in a static bioassay (SB) without medium renewal was compared in laboratorial conditions (water PY concentrations: 0.07-10 mg L⁻¹). Main findings in the SSB that assessed mainly the toxicity of PY and its metabolites were: increased levels of bile PY metabolites in good agreement with the profile of lipid peroxidation levels (LPO) in exposed fish relating PY exposure and oxidative damage; increased levels of PY-type compounds in the brain indicating their ability to cross the blood-brain barrier; increased levels of these substances in liver and muscle which are edible tissues for humans thus raising concern on potential adverse effects on consumers of fish from PY contaminated areas; a significant inhibition of glutathione S-transferase activity suggesting its involvement in PY detoxication as toxicant scavenger; finally, an almost complete impairment of the swimming velocity at all the PY concentrations linking sub-individual to higher population level effects. In the SB, where the overall toxicity of PY, its metabolites and environmental degradation products was evaluated, 19% and 79% of PY decay in test media was found at 12 and 96 h, respectively. In general, the effects were similar to those of SSB but with significant effects being induced at higher PY concentrations indicating that the parental compound is more toxic than its environmental degradation products. The other main differences relatively to the SSB were: increased levels of PY-type substances in the liver suggesting more accumulation in this organ. Therefore, these findings highlight the need of carefully considering experimental design options when assessing the toxicity of readily degradable substances to marine fish, and stress the importance of taking into consideration the toxicity of environmental degradation products in addition to toxic effects of the parental substance and its metabolites for marine ecological risk assessment.     

International trade in meat: the tip of the pork chop

This paper provides an original account of global land, water, and nitrogen use in support of industrialized livestock production and trade, with emphasis on two of the fastest-growing sectors, pork and poultry. Our analysis focuses on trade in feed and animal products, using a new model that calculates the amount of "virtual" nitrogen, water, and land used in production but not embedded in the product. We show how key meat-importing countries, such as Japan, benefit from "virtual" trade in land, water, and nitrogen, and how key meat-exporting countries, such as Brazil, provide these resources without accounting for their true environmental cost. Results show that Japan's pig and chicken meat imports embody the virtual equivalent of 50% of Japan's total arable land, and half of Japan's virtual nitrogen total is lost in the US. Trade links with China are responsible for 15% of the virtual nitrogen left behind in Brazil due to feed and meat exports, and 20% of Brazil's area is used to grow soybean exports. The complexity of trade in meat, feed, water, and nitrogen is illustrated by the dual roles of the US and The Netherlands as both importers and exporters of meat. Mitigation of environmental damage from industrialized livestock production and trade depends on a combination of direct-pricing strategies, regulatory approaches, and use of best management practices. Our analysis indicates that increased water- and nitrogen-use efficiency and land conservation resulting from these measures could significantly reduce resource costs.     

Long-term variation of PM2.5 levels and composition at rural, urban, and roadside sites in Hong Kong: Increasing impact of regional air pollution

Long-term study of air pollution plays a decisive role in formulating and refining pollution control strategies. In this study, two 12-month measurements of PM_2.5 mass and speciation were conducted in 00/01 and 04/05 to determine long-term trend and spatial variations of PM_2.5 mass and chemical composition in Hong Kong. This study covered three sites with different land-use characteristics, namely roadside, urban, and rural environments. The highest annual average PM_2.5 concentration was observed at the roadside site (58.0±2.0 μg m⁻³ (average±2σ) in 00/01 and 53.0±2.7 μg m⁻³ in 04/05), followed by the urban site (33.9±2.5 μg m⁻³ in 00/01 and 39.0±2.0 μg m⁻³ in 04/05), and the rural site (23.7±1.9 μg m⁻³ in 00/01 and 28.4±2.4 μg m⁻³ in 04/05). The lowest PM_2.5 level measured at the rural site was still higher than the United States’ annual average National Ambient Air Quality Standard of 15 μg m⁻³. As expected, seasonal variations of PM_2.5 mass concentration at the three sites were similar: higher in autumn/winter and lower in summer. Comparing PM_2.5 data in 04/05 with those collected in 00/01, a reduction in PM_2.5 mass concentration at the roadside (8.7%) but an increase at the urban (15%) and rural (20%) sites were observed. The reduction of PM_2.5 at the roadside was attributed to the decrease of carbonaceous aerosols (organic carbon and elemental carbon) (>30%), indicating the effective control of motor vehicle emissions over the period. On the other hand, the sulfate concentration at the three sites was consistent regardless of different land-use characteristics in both studies. The lack of spatial variation of sulfate concentrations in PM_2.5 implied its origin of regional contribution. Moreover, over 36% growth in sulfate concentration was found from 00/01 to 04/05, suggesting a significant increase in regional sulfate pollution over the years. More quantitative techniques such as receptor models and chemical transport models are required to assess the temporal variations of source contributions to ambient PM_2.5 mass and chemical speciation in Hong Kong.     

水污染治理工程的环境绩效审计

环境绩效审计的作用之一就是检查投入到环境治理上的资金到底发挥了多大的效益。本研究以五里湖综合整治工程效益审计案例为基础,提出环境效益评估的程序,将条件评估法应用于水污染治理工程项目审计案例中,分析了无锡市居民为改善水环境质量和对周边房产的支付意愿,并计算出五里湖水环境改善的效益和周边房产的增值效益。结果表明,综合整治工程实施后会带来可观的经济效益。最后,对条件评估法在政府环境绩效审计中应用存在的问题进行了讨论,以期为政府环境审计提供技术支持。