Observation Study of Aerosol Radiative Properities over China

With a simplified radiation balance model, study is performed of aerosol direct radiation forcing in relation to its optical properties and surface reflectance, indicating that with the thickened aerosol layer the earth-atmosphere system may increase or weaken the solar radiation albedo, depending upon different combinations of aerosol single scattering albedo (SSA,ω0), asymmetry factor (g), and surface albedo (αg) rather than relying directly on the aerosol optical depth (δ), which has its value just in proportion to the changed range of albedo alone. As indicated by the model results, systematic observations of aerosol radiative properties are required to make quantitative study of aerosol direct radiative forcing. Observational research of the properties has been undertaken based on ground and space measurements over China, including ground-based sunphotometer-aerosol optical depth (AOD), nephelometer-aerosol scattering coefficients, aethalometer-aerosol absorption coefficients, and MODIS products-retrieved AOD. The satellite retrieved AOD is validated against in situ sun photometer measured AOD, indicating that for eastern China remote sensing given AODs are acceptable owing mainly to lower surface reflectance there whereas for poor vegetation in the north of China the surface reflectance may be underestimated in AOD retrieval. However, appropriate modification of the scheme of aerosol remote sensing is likely to improve the retrieval accuracy. The aerosol single scattering albedo in dry condition is around 0.80 from surface-measured scattering and absorption coefficients. It requires further studies based on more observations to improve our understanding of the issue.     

一次沙尘暴过程中沙尘气溶胶对云物理量和辐射强迫的影响

利用MOD IS Aqua卫星反演和装载在Aqua上的CERES仪器观测资料,讨论了我国北方地区2004年3月26~28日沙尘暴过程中沙尘气溶胶对云物理特性和辐射强迫的影响。初步结果表明,沙尘气溶胶明显改变了云的物理特性,使云滴变小,含水量及光学厚度减少,减弱了云的净辐射强迫,云的冷却效应受到了抑制,相当于大气层顶沙尘气溶胶的增温作用。     

Influence of some essential environmental factors on the reductive precipitation of uranium by sulfate reducing bacteria

The rapid kinetics of microbial U （Ⅵ） reduction and low solubility of uraninite make this process a promising strategy for removing uranium from groundwater and preventing its further migration. Nevertheless, some environmental factors that can influence U（Ⅵ） bioreduction, such as pH, the concentration of coexistent anions（sulfate, nitrate） and toxicity of heavy metal cations[Cu（ Ⅱ ）, Zn（ Ⅱ ）, etc], are not well defined. In this paper, anaerobic batch experiments were performed to evaluate their effects on the enzymatic reduction of U （Ⅵ） by mixed cultures of sulfate-reducing bacteria （SRB）. Kinetics investigations under variable pH conditions demonstrated that U （Ⅵ） was mainly reduced during the first 48h. The yield of this bacterial reduction depended strongly on the pH and increased from 4.3% to 99.4% when the pH was raised from 2.0 to 6.0. No inhibition of U （Ⅵ） bioreduction occurred and the formation Of uraninite was concurrent with the precipitation of metal sulfide （ZnS/CuS） at an initial concentration of 20 mg/L Zn （ Ⅱ ） or 10 mg/L Cu （ Ⅱ ）. But addition of 25 mg/L of Zn （ Ⅱ ） or 15 mg/L of Cu （ Ⅱ ） to the bacterial medium stopped U （Ⅵ） reduction due to their toxicities to SRB. Assessment tests for heavy metal toxicity implied that Cu （ Ⅱ ） toxicity probably proceeds by a mechanism different from that of Zn （ Ⅱ ） toxicity. The Zn （ Ⅱ ）-induced inhibition of microbial activity can be eliminated, but Cu （ Ⅱ ） toxicity can generate permanent and irreversible damage to SRB. The sulfate concentration as high as 4000 mg/L did not appreciably interfere with U （Ⅵ） reduction, however, the anion level greater than 5000 mg/L significantly slowed the rate of U （Ⅵ） reduction. Moreover, it was found that U （Ⅵ） was not reduced by H2S produced during dissimilatory sulfate reduction.     

Heavy metal concentrations and Pb isotopic composition in urban and suburban aerosols of Hong Kong and Guangzhou, South China-Evidence of the long-range transport of air contaminants

Rapid urbanization and industrialization in South China has placed a great strain on the environment and human health. In the present study, the total suspended particulate matter （TSP） in the urban and suburban areas of Hong Kong and Guangzhou, the two largest urban centres in South China, was sampled from December 2003 to January 2005. The samples were analyzed for their concentrations of major elements （Al, Fe, Mg and Mn） and trace metals （Cd, Cr, Cu, Pb, V and Zn）, and for Pb isotopic composition. Elevated concentrations of metals, especially Cd, Pb, V and Zn, were observed in the urban and suburban areas of Guangzhou, showing significant atmospheric trace element pollution. Distinct seasonal patterns were observed in the heavy metal concentrations of aerosols in Hong Kong, with higher metal concentrations during the winter monsoon period, and lower concentrations during summer time. The seasonal variations in metal concentrations of the aerosols of Guangzhou were less distinct, suggesting the dominance of local sources of pollution around the city. The Pb isotopic composition in the aerosols of Hong Kong had higher ^206Pb/^207Pb and ^208Pb/^207Pb ratios in winter, showing the influence of Pb from the northern inland areas of China and the Pearl River Delta （PRD） region, and lower ^206Pb/^207Pb and ^208Pb/^207Pb ratios in summer, indicating the influence of Pb from the South Asian region and from marine sources.     

Study on treatment of wastewater from acid in-situ leaching of uranium ore with sulfate reducing bacteria

Synthetic surfactants are among the most widely used chemicals in the world （around 10 millions of tons are produced per year）, mainly as key components in detergent formulation, apart from other applications such as wetting agents or emulsifiers. Coastal ecosystems receive large quantities of these compounds and, after a relatively fast partial degradation in water, the remaining quantities end up in the sediments due to their high affinity for organic carbon in the particulate phase. We therefore focused our studies on sediments because they can be assumed to play an important environmental role acting as a sink for these contaminants. Moreover, because of their widespread use and source specificity, surfactants can usefully be employed as molecular indicators in sediments for more general contamination caused by human activities. This work deals with the vertical distribution in sediment cores of the main anionic surfactants, both linear alkylbenzene sulfonates （LAS） and alkyl ethoxysulfates （AES）, and non-ionic surfactants, including nonylphenol polyethoxylates （NPEOs） and alcohol polyethoxylates （AEOs）. In the case of LAS their degradation metabolites sulfophenyl carboxylic acids （SPCs） are also studied. The processes considered are degradation, sorption and diffusion occurring along the sedimentary column for the different homologues contained in the commercial surfactant mixtures. The most hydrophobic surfactants such as NPEOs and AEOs remain strongly attached to the particulate phase whereas polar metabolites such SPCs tend to be present in the pore water. Highest values of surfactants are found near the surface and, in most cases, there is a decrease in their concentration down the sediment core. Furthermore, the reduction in the average length of the ethoxylated chain in polyethoxylated surfactants, as well as the increase in the concentrations of SPCs at depths showing redox potential from -300 to -400 mV, suggests that surfactants may be degraded anaerobically in the sediment. In the case of LAS, these field results are compared with the data from laboratory experiments carried out in order to determine sorption capacity and anaerobic degradation.     

乌鲁木齐市大气硫酸盐化速率变化规律及治理措施

以九年乌鲁木齐市区大气中硫酸盐化速率监测数据资料为依据。分析乌鲁木齐市大气中硫酸盐化速率污染变化趋势。结果表明:乌鲁木齐市硫酸盐化速率变化有很明显的时间特征,与环境空气质量的变化也密切相关。提出削减污染源,加快清洁能源推广步伐,完善城市规划,进行产业结构调整,改善城市布局是解决乌鲁木齐市大气污染的有效途径。     

论河北丰宁牛圈银（金）矿床的成矿时限问题

南沙海槽的构造和沉积受控于南海的构造运动和加里曼丹西北大陆边缘的演化,具有适于天然气水合物形成的物源基础、温压条件、输导系统和储藏场所。似海底反射层(BSR)出现在水深650~2 800 m、海底下65~350 m深的晚中新世沉积物中,与褶皱、逆冲推覆构造及穹窿构造有关;沉积物中的甲烷含量和孔隙水的SO24-含量表现出异常变化特征,硫酸盐-甲烷界面(SMI)深度仅为8~11 m;表层沉积的自生石膏和黄铁矿的成岩环境与甲烷流体排溢引起的厌氧甲烷氧化(AOM)有关,这些地球物理和地球化学指标均指示南沙海槽发育天然气水合物。研究表明,南沙海槽沉积物的甲烷以二氧化碳还原型微生物成因为主,少量为混合气,海槽东南部可能是最有潜力的天然气水合物远景区。     

气溶胶光学厚度估测中的LASSO特征选择方法

气溶胶光学厚度估测中通常利用遥感信息构造的多种特征属性作为输入,然而,这些属性中常常存在数据噪音、相互关联性和缺失值,从而降低了估测精度和估测强健性。针对这个问题,基于最小绝对收缩和选择算子（least absolute shrinkage selection operator,LASSO）方法和气溶胶光学厚度反演的先验知识,提出了一种针对遥感卫星观测的高维数据进行特征选择的方法,利用2009年4月2日至2011年4月1日2 a间与全球197个气溶胶地基自动观测网站点时空同步的MODIS（moderate-resolution imaging spectroradiometer）遥感数据,采用常用的人工神经网络作为估测模型进行实验分析,表明该方法能结合反演先验知识对多种异质遥感属性进行分组,通过组间迭代保留关键特征,去除冗余属性,有效进行特征选择,从而显著提高气溶胶光学厚度的估测精度。     

大气环境中纳米颗粒物研究进展与存在问题

纳米颗粒物（Nanoparticles,NPs）因较同质量细颗粒物和粗颗粒物而言对人体健康危害大得多,日益受到国内外研究者的重视.结合研究结果,对国内外共87篇NPs相关文献进行调研,选取含有效数据文章进行统计分析.从NPs来源和形成机理、粒径分布和归宿、数浓度水平和化学组成及健康效应和研究手段等方面进行综述.针对我国NPs研究现状提出建议及研究重点:（1）开展NPs常规化监测及环境空气和排放源NPs理化性质研究;（2）系统研究NPs形成机理;（3）发展NPs离线及在线一体化源解析技术;（4）系统建立NPs采样及分析技术;（5）加强NPs毒理学、流行病学和防护研究.由于在采取措施降低TSP和PM_2.5过程中有可能导致NPs浓度大幅增加,对人体健康会产生较大危害,政府应同时加大对NPs来源和污染控制研究的投入力度.      

浅谈微生物在铀成矿中的作用及研究现状

微生物参与铀成矿的现象与活动证据广泛存在,而且它们互相依存共同实现着对铀元素的成矿作用。微生物参与成矿过程中,存在H2S气体与硫酸盐物质循环、Fe2+与Fe3+物质循环,在循环中能量被传递、电子被转移,促进了矿床中C、N、S、Fe、U等元素的循环,加快了有机、无机物之间的转换,为成矿细菌提供了能源、电子供体、受体,创造了有利的成矿环境,加快了铀成矿的进程。