大气二氧化硫浓度的光学测定方法

介绍了测定二氧化硫浓度的几种光学方法 ,指出了目前一些化学方法的局限性 ,特别对紫外荧光法的原理、二氧化硫的吸收光谱以及荧光光谱进行分析探讨 ,设计了实验分析系统 ,得出该方法具有操作简单、灵敏度高、可实时在线的智能化优点 ,将会成为今后研究的主导方向。     

农业非点源控制的美国经验借鉴

我国的农业非点源污染治理正处于攻坚期,但部分政策一定程度上缺少具体执行标准和规范,难以执行到位,法律法规碎片化、分散且难以评估执行效果。本文从美国治理非点源的国际经验出发,梳理了联邦层面的法律法规、农业环境管理机构的运作形式以及州层面流域管理规划和非点源控制计划。最后,根据国际经验提出了如下建议:一是建议要求各省在农业规划中加入推进农业流域治理清单;二是建议制定流域地表水质达标规划,实现点源与非点源联合管理;三是建议形成最佳管理实践规范技术指南,并对执行者进行相应补贴,形成监管机制;四是建议建立农业绿色补贴制度,鼓励地方形成可持续的农业发展机制。     

Allometric models for the estimation of above- and below-ground biomass of Jatropha curcas L. in semi-arid regions of Southern India

Jatropha curcas L. (Jatropha) is an important multipurpose tree valued for oil. In India, plans are underway to bring substantial area under this crop for meeting the biofuel requirements of the country. A study was conducted to develop allometric relationships in Jatropha to predict various biomass-related components (above ground and below ground) using easily measurable attributes, viz. collar diameter, tree height, number of branches, crown diameter, and crown depth. Further, it was aimed to establish the reliability of these relationships using an independent dataset obtained from varied management situations. Destructive sampling was carried out during the rainy season of 2011, when Jatropha plants were eight years old. Highly significant allometric relationships (F-values significant at 1% level) were obtained while predicting various biomass components (above, below, and total) using easily measurable attributes with R² values ranging from 0.89 to 0.98. Of all the predictors, collar diameter exhibited a highly significant relationship with total dry biomass per plant (R² = 0.97). The allometric relationships developed were validated with an independent dataset. The allometric relationships developed would serve as valuable tools for estimating total dry biomass production and carbon sequestration with reasonable accuracy in Jatropha systems, as they are proposed to be taken up in substantial area in the years to come.     

LivestockPlus: Forages,sustainable intensification,and food security in the tropics

The increased use of grain-based feed for livestock during the last two decades has contributed, along with other factors, to a rise in grain prices that has reduced human food security. This circumstance argues for feeding more forages to livestock, particularly in the tropics where many livestock are reared on small farms. Efforts to accomplish this end, referred to as the ‘LivestockPlus’ approach, intensify in sustainable ways the management of grasses, shrubs, trees, and animals. By decoupling the human food and livestock feed systems, these efforts would increase the resilience of the global food system. Effective LivestockPlus approaches take one of two forms: (1) simple improvements such as new forage varieties and animal management practices that spread from farmer to farmer by word of mouth, or (2) complex sets of new practices that integrate forage production more closely into farms’ other agricultural activities and agro-ecologies.     

超声-紫外光协同催化体系降解水中菲

以纳米TiO_2为催化剂,采用超声-紫外光协同催化体系降解水中菲,并考察了菲降解率的影响因素。实验结果表明:不同类型TiO_2对菲降解率的大小顺序为锐钛矿型TiO_2P25型TiO_2金红石型TiO_2;超声-紫外光协同催化体系对菲的降解率大于单独超声体系或紫外光催化体系,且均遵从一级反应动力学规律;在超声频率为60k Hz、声强为0.233 W/cm2、TiO_2投加量为0.06 g/L、pH为4.0、H_2O_2浓度为19.59 mmol/L的条件下降解75 min后,超声-紫外光协同催化体系对初始质量浓度为0.96 mg/L的菲的降解率可达76.78%。     

Big concerns with small projects: Evaluating the socio-ecological impacts of small hydropower projects in India

Although Small Hydropower Projects (SHPs) are encouraged as sources of clean and green energy, there is a paucity of research examining their socio-ecological impacts. We assessed the perceived socio-ecological impacts of 4 SHPs within the Western Ghats in India by conducting semi-structured interviews with local respondents. Primary interview data were sequentially validated with secondary data, and respondent perceptions were subsequently compared against the expected baseline of assured impacts. We evaluated the level of awareness about SHPs, their perceived socio-economic impacts, influence on resource access and impacts on human–elephant interactions. The general level of awareness about SHPs was low, and assurances of local electricity and employment generation remained largely unfulfilled. Additionally most respondents faced numerous unanticipated adverse impacts. We found a strong relationship between SHP construction and increasing levels of human–elephant conflict. Based on the disparity between assured and actual social impacts, we suggest that policies regarding SHPs be suitably revised.     

Dephenolization and detoxification of olive-mill wastewater (OMW) by purified biotic and abiotic oxidative catalysts

The capability of two oxidative catalysts, a laccase from Rhus vernicifera and birnessite, a manganese oxide, in the dephenolization and detoxification of two olive-mill wastewater (OMW) samples, C1 and C2, differing for complexity and composition, was evaluated. OMW phenolic extracts (EC1 and EC2) and mono-substrate solutions of phenols mostly present in OMW samples were also tested. Birnessite was more effective than laccase in removing the phenolic content from mono-substrate solutions (more than 70% of each initial phenolic concentration) and of either OMW samples or EC1 and EC2 extracts. For instance, 60% of the total phenolic content of EC1 was removed after 48-h treatment with 5 mg mL(-1) birnessite and the efficiency was lower as greater was the complexity of the OMW sample (only 17% removal from EC2 over the same time span). Phytotoxicity tests with Lepidium sativum and Lycopersicon esculentum seeds and antibacterial toxicity tests with Bacillus megaterium were performed on crude OMW samples and their extract and exhausted fractions before and after the catalytic treatment. Results demonstrated that (a) monomeric phenols were certainly but not exclusively responsible of OMW phytotoxicity, whereas their removal led to a quite complete elimination of the toxicity toward bacterial growth; (b) other components not removable by the oxidative catalysts very likely contribute to OMW phytotoxicity; and (c) the choice of the vegetal species to use in toxicity tests might be crucial for correct and easily interpretable results. Overall the results provided useful information on the possible use of oxidative catalysts for the efficient treatment of complex aqueous wastes such as those deriving from olive industry.     

Integration of traditional and innovative characterization techniques for flux-based assessment of Dense Non-aqueous Phase Liquid (DNAPL) sites

Key attributes of the source zone and the expanding dissolved plume at a trichloroethene (TCE) site in Australia were evaluated using trends in groundwater monitoring data along with data from on-line volatile organic compound (VOC) samplers and passive flux meters (PFMs) deployed in selected wells. These data indicate that: (1) residual TCE source mass in the saturated zone, estimated using two innovative techniques, is small ( 10 kg), which is also reflected in small source mass discharge ( 3 g/day); (2) the plume is disconnecting, based on TCE concentration contours and TCE fluxes in wells along a longitudinal transect; (3) there is minimal biodegradation, based on TCE mass discharge of  6 g/day at a plume control plane  175 m from source, which is also consistent with aerobic geochemical conditions observed in the plume; and (4) residual TCE in the vadose zone provides episodic inputs of TCE mass to the plume during infiltration/recharge events. TCE flux data also suggest that the small residual TCE source mass is present in the low-permeability zones, thus making source treatment difficult. Our analysis, based on a synthesis of the archived data and new data, suggests that source treatment is unwarranted, and that containment of the large TCE plume ( 1.2 km long,  0.3 km wide; 17 m deep;  2000–2500 kg TCE mass) or institutional controls, along with a long-term flux monitoring program, might be necessary. The flux-based site management approach outlined in this paper provides a novel way of looking beyond the complexities of groundwater contamination in heterogeneous domains, to make intelligent and informed site decisions based on strategic measurement of the appropriate metrics.     

天然有机物对零价铁去除水体中砷的影响研究

在研究零价铁对水体中砷去除动力学的基础上,着重探讨了天然有机物腐殖酸对零价铁除砷的影响.并对零价铁的腐蚀产物进行了分析.结果表明,水体中的砷可以通过在零价铁腐蚀产物上的吸附得到快速去除.腐殖酸显著降低了砷的去除率,这归因于腐殖酸与零价铁腐蚀产生的铁离子形成络合物,阻止了Fe(OH)3(或Fe(OH)2)沉淀的产生.腐殖酸浓度越高.砷的去除率越低.1.00 mg腐殖酸最多可以络合约0.75 mg铁离子.当铁离子与腐殖酸的络合达到饱和后,零价铁进一步腐蚀产生的铁离子可形成Fe(OH)3(或Fe(OH)2)沉淀,这些沉淀物可吸附水体中的腐殖酸和砷,从而加速砷的去除.冷冻干燥后的零价铁腐蚀产物的结构以无定型为主,含有少量的结晶化合物,包括γ-Fe2O3、γ-FeO(OH)和Fe3O4等.腐殖酸的存在可进一步增加腐蚀产物中的无定型成分.光电能谱(XPS)分析结果显示,吸附在腐蚀产物上的砷为5价,没有发现5价砷被还原成3价砷.在应用零价铁修复砷污染水体时,应考虑腐殖酸的影响.