塔里木河上游绿洲土壤表层盐分特征及其影响因子分析

选择塔里木河上游阿拉尔垦区,以农田、新开农田、撂荒地、人工林、天然林、盐碱地及荒草地等不同土地利用类型的样地土壤为研究对象,结合通径分析,研究了土壤中w(全盐)与盐源分布、盐分化学特性、土壤理化特性、地下水等影响因子的分布规律及相互关系. 结果表明,该区域盐分表聚特征明显,土壤表土层w(全盐)远大于心土层和底土层,各土地利用类型表土层w(全盐)表现为盐碱地最高(平均值为52.93g/kg),盐碱地>天然林>人工林>荒草地>撂荒地>农田>新开农田. 由通径分析结果可知,S_20-50〔心土层w(全盐)〕、SAR(钠吸附比)、SDR(钠钙镁比)、D_g(地下水埋深)、c(Cl-)/c(SO₄2-)、c(HCO₃-)、pH、ρ(土壤容重)、S_50-80〔底土层w(全盐)〕、SSP(可溶性钠百分率)对表土层w(全盐)的直接通径系数依次为0.415、0.414、-0.344、-0.201、0.200、0.162、0.092、-0.086、0.080、0.071. 土壤盐源分布和土壤盐分化学特性对表土层w(全盐)影响较大,其次是D_g,土壤理化特性对表土层w(全盐)影响相对较小. 反映盐源分布的S_20-50和反映土壤盐分化学特性的SAR是表土层w(全盐)的主要控制因子.      

Fume emissions during gas metal arc welding

The control of exposure to welding fumes is of increasing importance in promoting a healthy, safe and productive work environment. This article describes the effects of shielding gas composition on the amount and composition of welding fumes produced during gas metal arc welding (GMAW). The amount of fumes generated during welding was measured for steady current over a range of wire-feed speeds and arc voltages using the standard procedures contained in ANSI/AWS F1.2 [American Welding Society. ANSI/AWS F1.2. Laboratory method for measuring fume generation rates and total fume emission of welding and allied processes. Miami, Florida; 1992]. Results of these measurements show that the fume formation rates (FFRs) increase with CO₂ and O₂ in the shielding gas mixture. The lowest FFRs were obtained with the mixtures of Ar?+?2%CO₂ and Ar?+?3%CO₂?+?1%O₂. The highest FFRs were obtained with the mixtures of Ar?+?18%CO₂ and Ar?+?5%CO₂?+?4%O₂. The welding fumes contains mainly iron, manganese, silicon, titanium and sodium under oxide forms. The fume cluster particles have dimensions between 0.5 and 2?µm. The FFR was found to be governed by the transfer modes of molten metal, i.e. the current intensity and arc voltage, as well as by the shielding gas mixtures composition. Thus these parameters have to be taken into consideration before designing a welding process. Whenever possible, users of GMAW should use the lowest current intensity. However, when this is not possible, due to the constraints of process productivity, welders should use higher currents, but with Ar?+?2%CO₂ and Ar?+?3%CO₂?+?1%O₂ shielding mixtures, which will lead to smaller fume emissions.     

Groundwater quality in the major industrial area of Thessaloniki,Greece part 1: Chemical composition‐geochemical processes

Adsorption rates of Sb(V) ions on an activated alumina (AA) were analyzed by batchwise experiments, while the continuous adsorption, desorption, regeneration of AA, and multiple reuse cycles were studied by flow column tests. The adsorption rates increased quickly with the increases of shaking speed and operation temperature. The adsorbed Sb(V) ions were desorbed easily by a 50 mM NaOH solution, and a 41–90 times concentrated Sb(V) solution was yielded correspondingly. AA was effectively regenerated by desorption operation and ca. 93% of the initial adsorption capacity was retained after six times adsorption/desorption cycles.     

A comparison study of aerosol emissions sources in two receptor sites in Salvador (Brazil) city

Total suspended particles (TSP) and metal concentrations were determined in Salvador, Bahia, Brazil at two sites: a residential area and a residential‐commercial‐industrial neighborhood. The determined metals associated with atmospheric aerosols include Al, Ca, Cr, Cd, Fe, Mg, Mn, V, Zn and Na. Factor analysis was employed to identify the major atmospheric deposition sources. At one site the data were best represented by two sources: resuspended soil + marine aerosol and vehicular emissions, which represents 93% of the total system variance. In the second one the data were best represented by three sources: resuspended soil, metallurgy and building construction, which represents 79% of the total system variance.     

Differences in the rainwater composition on two consecutive days

The relationship between the rainwater composition on two consecutive rain days was analyzed. Logrono, a remote station in the North of Spain was chosen for the analyses. The concentration of the major ions in the rainwater of the first rain day is linearly related to the concentration of the second rain day except for those ions whose source is the soil (Ca²⁺ and Mg²⁺). These ions are related to SO₄ ^2? and NO₃ ^? in the first rain day, but not in the second.     

焦化废水中有机物的识别、污染特性及其在废水处理过程中的降解

采用液-液萃取辅以硅胶、氧化铝净化的方法,并结合GC/MS分析技术,系统分析了焦化废水中有机物的组成.在焦化废水中检测到15类558种有机物.根据有机物的分子结构、废水中的含量、毒性及环境效应,筛选出焦化废水中的特征性有机污染物,以区别于其它工业废水,可作为追溯环境中污染物来源的依据.经物理、生物和化学处理后,焦化废水中大部分有机物被去除,其中,对去除率的主要贡献是生物处理阶段.为了更好地考察生物处理阶段对有机污染物的去除特征,选定酚类、多环芳烃和喹啉类物质作为研究对象,分析了3类特征性污染物在A/O2工艺各单元中的去除状况及组成变化特征.     

The emergence of team helping norms: Foundations within members' attributes and behavior

This research examined the antecedents of organizational citizenship behavior helping norms in teams, specifically with regard to how members' personality, values, beliefs, and helping behavior predict the emergence of helping norms in newly formed project teams. We drew from theory on emergent phenomena and team composition research to propose and test a compilation model of how helping norms are influenced by having at least one member with particularly low (minimum) or high (maximum) levels of attributes that may influence helping‐norm development (i.e., conscientiousness, agreeableness, other‐oriented values, personal helping beliefs). We further examined the extent to which members' helping behaviors, as rated by peers, predicted helping norms and whether these behaviors mediated the relationship between individual attributes and helping norms. The results of a longitudinal study of 47 student project teams revealed that teams' minimums on agreeableness, other‐oriented values, and personal helping beliefs had direct relationships with helping‐norm emergence, and the effects of agreeableness were mediated through mean helping behavior. By contrast, teams' maximums on these attributes showed no relationships with helping norms, and only a team maximum on agreeableness was associated with teams' mean helping behavior. Copyright © 2011 John Wiley & Sons, Ltd.     

太原地区煤矸石作为建筑回填材料的试验研究

为了利用煤矸石作为建筑回填材料,控制其压实质量,以室内土工试验的方法,对太原地区某矿煤矸石进行了物理、力学等指标的试验研究。结果证明,所用煤矸石性能良好,性质较稳定,适合作为回填材料。并回归出该煤矸石的应力-应变关系式,得出了物理力学参数。     

北京冬季一次重污染过程的污染特征及成因分析

为了研究北京冬季重污染过程的污染特征及形成原因,选取2013年1月9~15日一次典型重污染过程,对污染期间气象要素、大气颗粒物组分特征和天气背景场进行综合研究.结果表明,此次大气重污染过程中PM₁₀和PM_2.5平均质量浓度分别为347.7μg/m³和222.4μg/m³,均超过环境空气质量标准(GB3095-2012)中规定的日均二级浓度限值.重污染时段PM_2.5中NH₄⁺、NO₃^-和SO₄^2-质量浓度之和占PM_2.5质量浓度的44.0%,OC/EC的平均比值为5.44,说明二次无机离子和有机物对此次污染过程中PM_2.5贡献较大.稳定的大气环流背景场、高湿度低风速的地面气象条件和低而厚的逆温层导致北京地区大气层结稳定,加上北京三面环山的特殊地形结构,是造成此次大气重污染过程的主要原因.     

人工芦苇湿地氨氮污染物去除及氨氧化菌群落多样性分析

对不同质量浓度的NH₃-N在水平潜流人工湿地内的去除过程进行考察,并且对比分析了去除率和硝化强度,利用PCR-DGGE技术研究了ρ(NH₃-N)及植物种植等因素对人工湿地中AOB(氨氧化细菌)群落结构的影响. 结果表明:在水力停留时间为2.5d的情况下,模拟低污染水ρ(NH₃-N)分别为0.6~0.7和4.5~5.0mg/L时,芦苇湿地对TN的去除率分别为81.9%和62.2%. 较高的ρ(NH₃-N)和种植芦苇有利于提高湿地硝化强度和AOB群落多样性. 系统运行50d时,处理高ρ(NH₃-N)和低ρ(NH₃-N)低污染水的芦苇湿地的硝化强度分别为0.164和0.103mg/(kg·h);AOB群落Shannon-Weaver多样性指数(系统运行90d时)分别为2.32和1.75. 处理高ρ(NH₃-N)的低污染水时,空白湿地和芦苇湿地的硝化强度分别为0.082和0.164mg/(kg·h);AOB群落Shannon-Weaver多样性指数(系统运行90d时)从1.95增至2.32.