Allocation and source attribution of lead and cadmium in maize (Zea mays L.) impacted by smelting emissions

Plants grown in contaminated areas may accumulate trace metals to a toxic level via their roots and/or leaves. In the present study, we investigated the distribution and sources of Pb and Cd in maize plants (Zea mays L.) grown in a typical zinc smelting impacted area of southwestern China. Results showed that the smelting activities caused significantly elevated concentrations of Pb and Cd in the surrounding soils and maize plants. Pb isotope data revealed that the foliar uptake of atmospheric Pb was the dominant pathway for Pb to the leaf and grain tissues of maize, while Pb in the stalk and root tissues was mainly derived from root uptake. The ratio of Pb to Cd concentrations in the plants indicated that Cd had a different behavior from Pb, with most Cd in the maize plants coming from the soil via root uptake.     

Seasonal and spatial changes of free and bound organic acids in total suspended particles in Guangzhou,China

The concentrations and compositions of free and bound organic acids in total suspended particles from typical urban, suburban and forest park sites of Guangzhou were determined in this study. The free form of organic acids (solvent extractable) in aerosols in Guangzhou varied with site and season. The suburban samples contained the highest contents of alkanoic, alkenoic and dicarboxylic acids. These findings were consistent with a higher supply of hydrocarbons and NOx in the suburban area. However, concentrations of aromatic acids were similar in the urban, suburban and forest park sites. Generally, winter season samples of the acids from anthropogenic sources contained more organic acids than summer season samples due to stronger removal by wet deposition in the summer. For the acids from botanic sources, the summer season samples were higher. In addition to the free acids, bound acids (solvent non-extractable) mainly formed by esterification of free acids were also found in the samples. In general, bound acids were higher than free acids. Esterification is mainly controlled by the pKa of organic acids and the atmospheric pH value. This explains why aromatic and dicarboxylic acids occur mainly as bound forms and why the samples from urban sites contained high levels of bound acids as the pH of rain water can reach 4.53.Concentrations of alkanoic and alkenoic acids in the aerosols of Guangzhou were much higher than those in the other areas studied.     

四川农业资源可持续利用研究

四川是全国农业大省之一。伴随着经济社会的快速发展,农业、农村环境污染和生态破坏现象日益突出,经济社会快速发展和生态环境承载力脆弱、资源短缺的矛盾依然十分尖锐。实现农业资源的可持续利用,是发展农业生产的重大问题。分析评价了四川农业资源开发利用现状及其发展变化趋势,提出了实现农业资源可持续利用的对策措施:节约集约用地,严格控制建设占用耕地,努力提高耕地综合生产能力;提高水资源利用率,防治水资源污染;加强土地整理复垦工作,努力补充有效耕地面积;搞好水土保持和治沙防沙工作;加快实施农业循环经济建设。     

The changes of densities and patterns of roads and rural buildings: a case study on Dongzhi Yuan of the Loess Plateau, China

Roads and buildings are considered as primary causes of rural landscape changes. In this study, linear regression models were used to analyze the dynamic influences of environmental factors and variables on roads and rural buildings from 1979 to 2005 in Dongzhi Yuan (tableland) of the Loess Plateau, China. The relationship between roads and rural buildings and their effects on Dongzhi Yuan are discussed also. The results showed that three environmental factors (topography, land cover, and development level) explained roads better than rural buildings referring densities and patterns. The environmental variables significantly related to roads have decreased, whereas those related to rural buildings have increased over time. Among these significant variables, percent of farmland mostly determined the densities and patterns of both roads and rural buildings. There was significant correlation between roads and rural buildings in terms of density and pattern. In addition, roads and rural buildings have increased greatly in gully areas of this region. Therefore, more attention should be paid to planning of roads and rural buildings in Dongzhi Yuan.     

Electron donor capacity of reducing dissolved organic matter from crop residue decomposition as probed by chronoamperometry

Reducing dissolved organic matters (RDOMs) from the anaerobic decomposition of crop residue can greatly affect the physicochemical and biological properties of soils. Electrochemical methods that can effectively protect them from oxidation and rapidly obtain results, such as differential pulse voltammetry (DPV), have been applied to qualitatively analyzing properties of RDOMs. However, the donated amount of electrons from RDOMs as a capacity factor may be more crucial for evaluating their important roles. For the first time, matured chronoamperometry (CA) was applied to quantitatively determining the electron donor capacities of RDOMs in crop residue management. The electron donor capacities of RDOMs from green manure were much higher than those from rice straw, which indicated that the former had greater effect on the redox status and reactions of soil. Chronoamperometry was proposed as a practical and effective method to quantitatively characterize RDOMs from residue decomposition.     

硝化菌的分离及特性分析

从联合脱硫脱氮填料塔中的陶粒上分离出两株硝化菌,命名为NS2和NS5,这2种菌均为革兰氏阴性菌。硝化能力测试结果表明:NS2和NS5能利用亚硝酸盐作为氮源,将亚硝酸盐转化成硝酸盐,硝化速率都达到60%以上。部分长度的16S rDNA序列同源性分析表明,NS2和NS5与Delftia sp.的同源性高达99%,并用MEGA程序对该菌株进行了系统发育进化分析。结合形态观察和生理生化鉴定,初步鉴定NS2,NS5为戴尔福特菌(Delftia sp.)。     

全氟辛烷磺酸盐(PFOS)在藻渣/小球藻上的吸附行为及机理

为了开发新型廉价生物吸附剂,以高效吸附去除水体中全氟辛烷磺酸盐(PFOS),对小球藻提取生物柴油后的藻渣吸附酸性水体中的PFOS进行了吸附行为及机理的研究。小球藻提取生物质柴油后,比表面积、孔容、孔径几乎没有变化;等电点由3.3降低至2.7;蛋白质含量由51.45%提高到57.35%。在酸性条件下(pH≤3),小球藻和藻渣对PFOS的吸附率均达到99%以上;随着pH值增加至7,二者的吸附去除率迅速降低,但仍保持在22%~26%。小球藻和藻渣对PFOS的最大吸附容量分别为353.69 mg/g和444.83 mg/g。Freundlich模型能较好地拟合二者对PFOS的吸附数据,表明为多层吸附,即小球藻以静电吸引的形式吸附PFOS阴离子,并疏水分配至所含蛋白质中;而藻渣中含量较高的蛋白质对PFOS的疏水性分配作用是导致藻渣吸附量增高的主要原因。     

Spatial distribution and ecotoxicological risk assessment of heavy metals in surface sediments of the southern Bohai Bay, China

The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and organic carbon in surface sediments, collected from the southern Bohai Bay, were determined to assess the potential contamination and determine the environmental risks associated with heavy metals. Results showed that heavy metal concentrations in the sediments generally met the China Marine Sediment Quality criteria. Both the ecotoxicological index and the potential ecological risk index suggest that the combined ecological risk of the six studied metals may be low, with the highest ecotoxicological potential zones located in the offshore area. The methods of enrichment factor and geoaccumulation index suggested that elevated concentrations of Cd, Cr, and Ni are presented in the region. Multivariate analysis also indicated that the lithogenic factor dominates the distribution of most part of the considered metals in the study area, whereas Cd and Cr are clearly influenced by anthropogenic inputs. The results of this study are likely to be a useful tool to authorities in charge of sustainable marine management.     

氧化电解法处理工业含硫恶臭气体的研究

利用铁盐溶液,通过气体超微细分散式吸收反应器和电化学再生系统结合的反应器,对中高浓度含硫恶臭气体进行吸收及电化学再生过程进行了初步研究.结果表明:当反应液位高度为55 cm、温度为20 ℃和H+浓度小于1.5 mol/L时,进气浓度小于1 000 mg/m3时,含硫恶臭气体处理效率可到达96%以上.当液位高度为55 c...     

大气中甲酸和乙酸测定方法研究

本文研究了一种用红色担体经强碱(KOH)处理作为吸附的载体,去离子水超声浸取,离子色谱法分析测定大气中甲酸和乙酸的方法。对固体吸附管的特性进行了实验室内模拟及野外研究。在采样体积为2.4m~3时,该法对大气中甲、乙酸的最低检出限分別为0.2μg/m~3和0.4μg/m~3。利用此法,测出北京冬季大气中甲、乙酸浓度分別为0.5—2.0μg/m~3和0.6—8.7μg/m~3,广州白云山春季大气中甲、乙酸浓度分別为0.2—1.0μg/m~3和<0.4—2.0μg/m~3,桂林市大气中甲、乙酸浓度分别为0.37—0.4μg/m~3和0.5—1.1μg/m~3。