长沙“百里茶廊”茶园土壤重金属含量及环境质量特征

采用野外调查采样和室内分析方法测定了长沙"百里茶廊"茶叶基地土壤重金属含量,研究了其分布特征及变化规律,并用污染指数方法评价了其土壤环境质量.结果表明,土壤全铅、全汞、全镉、全铬、全砷和全镍含量值基本在土壤背景值范围内,平均含量值分别为42.7、0.068、0.074、92.2、12.4和19.5 mg/kg.均低于无公害茶叶产地环境条件标准(NY 5020-2001)所要求的最低值.根据国家<土壤环境质量标准>,长沙"百里茶廊"茶叶基地的土壤环境质量全部符合国家二级标准.且汞、镉、镍元素的含量达到国家一级标准.除湘丰茶场土壤铬的单项污染指数为0.837,处于警戒级别土壤质量尚清洁外,其它5种重金属的单项污染指数均小于0.7,处于安全级别土壤清洁无污染.6个茶叶基地的综合污染指数均小于0.7.表明长沙"百里茶廊"茶叶基地的土壤环境质量总体达到安全级别土壤清洁无污染.适合无公害茶叶基地的建设.     

Loss coefficient of nitrogenous non-point source pollution under various precipitation conditions

In this study, calibrations of non-point source (NPS) pollution models are performed based on Black River basin historical real-time runoff data, sedimentation record data, and NPS sources survey information. The concept of NPS loss coefficient for the watershed or the loss coefficients (LC) for simplicity is brought up by examining NPS build-up and migration processes along riverbanks in natural river systems. The historical data is used for determining the nitrogenous NPS loss coefficient for five land use types including farmland, urban land, grassland, shrub land, and forest under different precipitation conditions. The comparison of outputs from Soil and Water Assessment Tool (SWAT) model and coefficient export method showed that both methods could obtain reasonable LC. The high Pearson correlation coefficient (0.94722) between those two sets of calculation results justified the consistency of those two models. Another result in the study is that different combinations of precipitation condition and land use types could significantly affect the calculated loss coefficient. As for the adsorptive nitrogen, the order of impact on LC for different land use types can be sorted as: farm land > urban land > grassland > shrub land > forest while the order was farmland > grass land > shrub land > forest s>urban land for soluble nitrogen.     

东北春麦对气候变化的响应预测

农业是气候变化的主要敏感部门之一,气候要素的变化必然会对农业生产带来影响,反之通过一定的管理措施,农业也可以一定程度上适应气候变化.文章采用英国 PRECIS(Providing Regional Climate for Impacts Simulation)模型输出的未来气候变化情景,利用CERES-wheat模型研究了2070s气候变化对我国东北春麦生产的影响,并对不同地区的适应水平进行了分析.结果表明,气候变化会对东北的春小麦生产带来不利影响,东北西部地区产量下降明显,灌溉春麦的产量降低幅度小于雨养春麦.CO2的肥效作用可以缓解产量的降低幅度,同时通过品种更换以及灌溉等措施也可以降低不利影响,综合的适应措施较单一措施的补偿效果更好.     

稠油热采污水回用锅炉给水处理工艺研究

采用生物接触氧化-超滤-反渗透集成工艺处理稠油热采污水,出水作为试验区稠油注蒸汽热采高压锅炉给水。运行结果表明:出水各项指标均达到试验区注汽锅炉给水水质要求,实现了稠油污水的资源化循环利用。     

进水中碳水化合物分子大小对污泥沉降性能的影响

为弄清楚碳水化合物分子大小和污泥沉降性能之间的影响关系,在3个序批式系统中,分别以颗粒型淀粉、溶解型淀粉和葡萄糖为碳源,考察了长期运行中系统的污泥沉降性能和处理能力.结果证明:碳水化合物分子越小,活性污泥对环境的变化越敏感,当运行条件不利时越容易引发污泥膨胀问题;大分子碳源吸附于絮体内部能够提高污泥的沉降性能;糖类作碳源时,活性污泥的PHA贮存量约为0.6mmol C/L,但系统SVI仍然能够维持在150mL/g以下;胞外聚合物中多糖与蛋白质(C/P)的比值与污泥的SVI呈正相关性,SVI从100mL/g增长到600mL/g,C/P比从0.248增长到1.201;以颗粒型淀粉、溶解型淀粉和葡萄糖为碳源时,系统的优势丝状菌分别为Type 0041、M. parvicella和S. natans;进水以葡萄糖作单一碳源时,系统的除磷能力能达到80%以上.     

活性炭颗粒对超细颗粒物的过滤性能

UFPs(超细颗粒物)对人体危害较大且难以脱除,但活性炭颗粒床利用多孔结构可以提高其过滤效率. 为探究试验条件对UFPs过滤效率的影响以及活性炭孔隙结构和UFPs过滤效率之间的关系,以实验室发生UFPs为研究对象,活性炭为过滤介质,对活性炭颗粒粒径、滤层厚度以及表观风速等条件对过滤UFPs的影响进行了研究,并通过对比过滤前后活性炭的孔径分布,分析活性炭多孔性与UFPs的关系. 结果表明:当活性炭颗粒平均粒径由2.50 mm减至0.45 mm、滤层厚度由20 mm增至100 mm、表观过滤风速由4.25 cm/s降至0.84 cm/s时,总过滤效率分别由41.87%、49.39%、68.24%升至86.27%、89.29%、83.04%;但从活性炭的单颗粒过滤效率和过滤质量角度来看,在活性炭颗粒粒径大、滤层厚度小、表观过滤风速低的条件下,更有利于单个活性炭颗粒的过滤作用的发挥;当UFPs粒径小于14.3 nm时,UFPs发生“热反弹”效应,并且主要过滤机理是扩散效应,但随着UFPs粒径增大,拦截和惯性碰撞对过滤效率的作用增强;活性炭500 nm以下的孔隙结构对脱除UFPs起着重要作用. 研究显示,选择含有更多500 nm以下孔隙的多孔材料更有利于过滤UFPs.      

Sustainability of urban drainage management: a perspective on infrastructure resilience and thresholds

Urban wastewater infrastructures have been threatened by natural and socioeconomic disturbances. This study investigates infrastructure resilience against the risks of long-term changes rather than natural disasters. Urban expansion that leads to an increased urban runoff and massive population movements that cause fluctuations in domestic emissions are considered in this study. Pollution permits for water bodies are adopted as constraints on wastewater infrastructures. A land use-based accounting method, combined with a grid-based database, is developed to map domestic discharge and urban runoff to service areas of wastewater treatment plants. The results of a case study on downtown Sanya, the most famous seashore tourist attraction in China, show that the average resilient values of three sub-catchment areas in 2010 were -0.57, 0.10 and 0.27, respectively, a significant spatial variation. The infrastructure in the Sanya River sub-region is the least flexible, and is more likely to fail due to unstable inflows. The resiliencies will increase to 0.59, 1.01 and 0.54, respectively, in 2020, a considerable improvement in robustness. The study suggests that infrastructure resilience needs to be taken into further consideration for urban planning and the related realm of urban governance to foster more robust wastewater management under various risks.     

硝酸铵与硝铵磷热稳定性对比研究

为了研究硝铵磷的热稳定性,用DSC－TG同步热分析仪测试了硝酸铵的热分解过程,根据升温速率分别为5,10,15 K／min的DSC和TG－DTG曲线,利用Ozawa法和Kissinger法求得的硝酸铵的活化能基本一致。用Rogers公式和Arrhenius公式求得指前因子和速率常数分别为1．62×1010 s－1,1．07×10－18 s－1（120℃）;硝酸铵在升温速率为5 K／min时,分解峰值温度的活化焓、活化熵、活化自由能分别为102．76 kJ／mol ,－62．35 J／（K·mol ）,134．98 kJ／mol;对比了硝酸铵和硝铵磷的DSC曲线,结果表明硝铵磷的吸热分解峰值温度低于硝酸铵,热稳定性更好。     

Foliar uptake and metal(loid) bioaccessibility in vegetables exposed to particulate matter

At the global scale, high concentrations of particulate matter (PM) enriched with metal(loid)s are currently observed in the atmosphere of urban areas. Foliar lead uptake was demonstrated for vegetables exposed to airborne PM. Our main objective here was to highlight the health risk associated with the consumption of vegetables exposed to foliar deposits of PM enriched with the various metal(loid)s frequently observed in the atmosphere of urban areas (Cd, Sb, Zn and Pb). Leaves of mature cabbage and spinach were exposed to manufactured mono-metallic oxide particles (CdO, Sb₂O₃ and ZnO) or to complex process PM mainly enriched with lead. Total and bioaccessible metal(loid) concentrations were then measured for polluted vegetables and the various PM used as sources. Finally, scanning electronic microscopy coupled with energy dispersive X-ray microanalysis was used to study PM–phyllosphere interactions. High quantities of Cd, Sb, Zn and Pb were taken up by the plant leaves. These levels depended on both the plant species and nature of the PM, highlighting the interest of acquiring data for different plants and sources of exposure in order to better identify and manage health risks. A maximum of 2 % of the leaf surfaces were covered with the PM. However, particles appeared to be enriched in stomatal openings, with up to 12 % of their area occupied. Metal(loid) bioaccessibility was significantly higher for vegetables compared to PM sources, certainly due to chemical speciation changes. Taken together, these results confirm the importance of taking atmospheric PM into account when assessing the health risks associated with ingestion of vegetables grown in urban vegetable crops or kitchen gardens.     

水资源污染与水安全问题探讨

随着工农业生产的发展和人们生活水平的提高 ,用水量急增 ,与此同时 ,绝大多数未经处理的巨量的工业废水和城市污水便排入水体 ,造成对有限水资源的严重污染。为此 ,笔者重点分析我国目前水资源状况 ;讨论了水资源合理利用的重要性 ;提出了强化水处理工艺及保护水资源的措施 ;指出了提高水的安全性的关键所在。