Greenhouse gas abatement strategies for animal husbandry

Agriculture contributes significantly to the anthropogenic emissions of non-CO₂ greenhouse gases methane and nitrous oxide. In this paper, a review is presented of the agriculture related sources of methane and nitrous oxide, and of the main strategies for mitigation. The rumen is the most important source of methane production, especially in cattle husbandry. Less, but still substantial, amounts of methane are produced from cattle manures. In pig and poultry husbandry, most methane originates from manures. The main sources of nitrous oxide are: nitrogen fertilisers, land applied animal manure, and urine deposited by grazing animals. Most effective mitigation strategies for methane comprise a source approach, i.e. changing animals’ diets towards greater efficiencies. Methane emissions, however, can also be effectively reduced by optimal use of the gas produced from manures, e.g. for energy production. Frequent and complete manure removal from animal housing, combined with on-farm biogas production is an example of an integrated on-farm solution. Reduced fertiliser nitrogen input, optimal fertiliser form, adding nitrification inhibitors, land drainage management, and reduced land compaction by restricted grazing are the best ways to mitigate nitrous oxide emissions from farm land, whereas, management of bedding material and solid manure reduce nitrous oxide emissions from housing and storage. Other than for methane, mitigation measures for nitrous oxide interact with other important environmental issues, like reduction of nitrate leaching and ammonia emission. Mitigation strategies for reduction of the greenhouse gases should also minimize pollution swapping.     

中国主要电子废物产生量估算

在分析了电子废物类型及其可能造成的主要环境问题的基础上。根据电子电器产品的销量、社会保有量以及产品寿命期等因子建立模型对我国2000-2010年间的电脑、电视机、冰箱、洗衣机、空调等5大类电子电器产品的年度废弃量进行估算。结果显示到2003年电脑年度废弃量达到447万台，总体呈增长趋势；电视机、冰箱的废弃量在2003年分别达到4229万台和976万台；洗衣机年度废弃量有一定波动。大约在2005年达到一个高峰，废弃量为1521万台；空调废弃量相对于其他家电较少，但一直处于稳步增长期。并在此基础估算了我国2003年主要电子废物中的可回收资源含量。量大而且增长较快的电子废物的处置和资源再生化将是我国电子废物管理面临的一个难题。     

石臼漾人工湿地冬夏季全程氨氧化微生物的分布、群落结构及其影响因素研究

湿地作为水体与陆地之间的过渡地带,具有独特的生态环境特性,是氮循环反应的关键区域.研究湿地生态系统中的全程氨氧化过程（complete ammonia oxidation,comammox）,解析该区域中comammox细菌的分布与群落结构特征,补充了此前该新型氨氧化微生物在湿地生态系统中分布特征的研究空白,对于完善comammox细菌在各种不同生态系统中分布情况的研究具有重要意义.本研究在石臼漾人工湿地中于冬夏两季分别采集了大沟中心、大沟边缘、小沟中心和小沟边缘的表层沉积物样品,利用PCR、荧光定量PCR和amoA功能基因高通量测序等方法,解析人工湿地中comammox细菌的时空分布与群落结构特征.主要研究结果如下：①所有样品中均检测到了comammox细菌,其丰度为1.77×10⁵~4.07×10⁷ copies·g^-1.冬季,comammox细菌丰度在大沟中高于氨氧化细菌（ammonia oxidizing bacteria,AOB）和氨氧化古菌（ammonia oxidizing archaea,AOA）,在小沟中高于AOB,但低于AOA;夏季,comammox细菌丰度在所有样点中均高于AOB和AOA.②冬夏两季样品中,comammox细菌丰度与底物NH₄⁺-N浓度均呈负相关关系,且夏季样品中呈显著性负相关.③主坐标分析（Principle Coordinate Analysis,PCoA）与多样性分析结果表明,comammox细菌群落结构具有空间异质性,且冬季物种多样性高于夏季.     

铝系混凝剂优势形态分析及其混凝特性

聚合氯化铝（PACl）是常用的水处理混凝剂,在应用过程中通常表现出比传统铝盐更为优异的效果.研究表明,这种优异性能主要得益于其特殊的组成,特别是高分子聚合物Al₁₃和Al₃₀独特的物化特性.Al₁₃和Al₃₀是铝离子水解过程中的中间产物,在地球科学和环境化学等领域有着重要的研究价值.于水处理而言,二者的结构和分子特性是研究者关注的重点,大量研究基于此展开,很多重要的发现为实际应用奠定了基础.基于对PACl及其组成性质的研究,本文对PACl的混凝特性及其优势形态分子的分析进行了综合阐述.     

陆浑水库沉积物重金属空间分布特征及风险评价

为了解洛阳市饮用水水源地陆浑水库沉积物中重金属污染程度,采集32个点位的表层沉积物,分析6种重金属（Cd、Cr、Cu、Ni、Pb和Zn）的空间分布特征,并运用地累积指数法、潜在生态风险指数和聚类分析等方法对研究区重金属污染程度进行评价、生态风险评价及源解析.结果表明：Cd、Cu、Pb和Zn含量超过黄河流域河南段重金属土壤背景值,分别是其8.8、2.0、6.5、2.3倍,重金属存在明显富集,且主要污染集中于坝前区域.地累积指数法评价结果显示,Cd为强污染,Pb为中-强污染.潜在生态风险指数表明,陆浑水库沉积物重金属风险呈自上游至下游逐渐增强的趋势,总体处于高度生态危害,潜在生态风险指数均值达到312.94,其中Cd为主要贡献因子.富集系数法和聚类分析结果显示：Cd、Cu、Pb和Zn主要为人为源,Cr和Pb以自然源为主.总体而言,陆浑水库沉积物中重金属Cd和Pb污染相对较重,可能会对水库水环境构成威胁.     

双酚S在两种典型地带性土壤中的吸附/解吸行为研究

采用批平衡实验方法研究了双酚S（BPS）在两种典型地带性土壤中的吸附/解吸行为.结果表明,吸附动力学曲线符合拟二级动力学方程.吸附等温线呈非线性,且同时符合Freundlich和Langmuir方程.相比而言,BPS更易吸附在高有机质含量的黑土中,298 K反应温度下BPS在黑土和红壤上的最大吸附容量分别为497.8和156.6 mg·kg^-1.吸附到两种土壤中的BPS存在解吸滞后现象,这可能是由于BPS以化学吸附和微孔扩散的形式存在于土壤中的缘故.溶液pH与BPS在土壤中的吸附容量呈负相关关系,即中性形态的BPS比阴离子形态的BPS具有更高的吸附容量.与结构类似物双酚A（BPA）的吸附相比,BPS在土壤中的吸附量更低,因此具有更高的迁移能力,可能会引起更高的环境健康风险.本研究结果为了解BPS在土壤中的迁移规律提供了数据支持.     

Tuning the fill percentage in the hydrothermal synthesis process to increase catalyst performance for ozone decomposition

The performance of Ce-OMS-2 catalysts was improved by tuning the fill percentage in the hydrothermal synthesis process to increase the oxygen vacancy density. The Ce-OMS-2 samples were prepared with different fill percentages by means of a hydrothermal approach (i.e. 80%, 70%, 50% and 30%). Ce-OMS-2 with 80% fill percentage (Ce-OMS-2-80%) showed ozone conversion of 97%, and a lifetime experiment carried out for more than 20?days showed that the activity of the catalyst still remained satisfactorily high (91%). For Ce-OMS-2-80%, Mn ions in the framework as well as K ions in the tunnel sites were replaced by Ce⁴⁺, while for the others only Mn ions were replaced. O₂-TPD and H₂-TPR measurements proved that the Ce-OMS-2-80% catalyst possessed the greatest number of mobile surface oxygen species. XPS and XAFS showed that increasing the fill percentage can reduce the AOS of Mn and augment the amount of oxygen vacancies. The active sites, which accelerate the elimination of O₃, can be enriched by increasing the oxygen vacancies. These findings indicate that increasing ozone removal can be achieved by tuning the fill percentage in the hydrothermal synthesis process.     

Bioassay: A useful tool for evaluating reclaimed water safety

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis. However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water. Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water. Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards. Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended. Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well. Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.     

Influence of floc dynamic protection layer on alleviating ultrafiltration membrane fouling induced by humic substances

Cake layer formation is inevitable over time for ultrafiltration (UF) membrane-based drinking water treatment. Although the cake layer is always considered to cause membrane fouling, it can also act as a “dynamic protection layer”, as it further adsorbs pollutants and dramatically reduces their chance of getting to the membrane surface. Here, the UF membrane fouling performance was investigated with pre-deposited loose flocs in the presence of humic acid (HA). The results showed that the floc dynamic protection layer played an important role in removing HA. The higher the solution pH, the more negative the floc charge, resulting in lower HA removal efficiency due to the electrostatic repulsion and large pore size of the floc layer. With decreasing solution pH, a positively charged floc dynamic protection layer was formed, and more HA molecules were adsorbed. The potential reasons were ascribed to the smaller floc size, greater positive charge, and higher roughness of the floc layer. However, similar membrane fouling performance was also observed for the negative and positive floc dynamic protection layers due to their strong looseness characteristics. In addition, the molecular weight (MW) distribution of HA also played an important role in UF membrane fouling behavior. For the small MW HA molecules, the chance of forming a loose cake layer was high with a negatively charged floc dynamic protection layer, while for the large MW HA molecules it was high with a positively charged floc dynamic protection layer. As a result, slight UF membrane fouling was induced.     

Cytotoxicity of the soluble and insoluble fractions of atmospheric fine particulate matter

Inhaled atmospheric fine particulate matter(PM_(2.5)) includes soluble and insoluble fractions,and each fraction can interact with cells and cause adverse effects.PM_(2.5) samples were collected in Jinan,China,and the soluble and insoluble fractions were separated.According to physiochemical characterization,the soluble fraction mainly contains watersoluble ions and organic acids,and the insoluble fraction mainly contains kaolinite,calcium carbonate and some organic carbon.The interaction between PM_(2.5) and model cell membranes was examined with a quartz crystal microbalance with dissipation(QCM-D) to quantify PM_(2.5) attachment on membranes and membrane disruption.The cytotoxicity of the total PM_(2.5) and the soluble and insoluble fractions,was investigated.Negatively charged PM_(2.5) can adhere to the positively charged membranes and disrupt them.PM_(2.5)also adheres to negatively charged membranes but does not cause membrane rupture.Therefore,electrostatic repulsion does not prevent PM_(2.5) attachment,but electrostatic attraction induces remarkable membrane rupture.The human lung epithelial cell line A549 was used for cytotoxicity assessment.The detected membrane leakage,cellular swelling and blebbing indicated a cell necrosis process.Moreover,the insoluble PM_(2.5) fraction caused a higher cell mortality and more serious cell membrane damage than the soluble fraction.The levels of reactive oxygen species(ROS) enhanced by the two fractions were not significantly different.The findings provide more information to better understand the mechanism of PM_(2.5) cytotoxicity and the effect of PM_(2.5) solubility on cytotoxicity.