The critical levels and the maximum metal uptake for wheat and rice plants when applying metal oxides to soil

Abstract

Wheat is more sensitivity to CdO and ZnO compared with rice plant. The yield of wheat decreased by 30% in the presence of 30 ppm Cd, but that of rice plants by only 8%. The critical levels of meal uptake by wheat and rice plants for applying metal oxides to soil (CdO, ZnO, PbO) were determined. The highest concentration obtained for wheat grain was 141 μg/g Cd at the Cd 10,000 ppm in soil. This value is higher the value of 4.97 μg/g for unpolished rice and higher than any other we have seen in the reports for treatment with CdO. Also, as concentration of more than 1.0 μg/g Cd in wheat was obsertced at 5 ppm Cd, while similar concentrations for rice plants were observed at 30 ppm Cd in soil.     

控制Na~+转运以及维持Na~+/K~+平衡有助于提高植物的耐盐性

盐害(包括土壤次生盐渍化)造成的日益严重的环境问题已在世界范围内引起了广泛关注。大量针对植物耐盐分子机制的研究已开展,旨在更好地了解植物自身的耐盐机制。到目前为止,已获取了大量关于植物耐盐性机制的信息。同时,人们正在形成一个共识,即植物维持自身细胞离子平衡的能力是其具有耐盐性的关键。Na+/H+、K+/H+和Na+/K+逆向转运蛋白及其同源蛋白在植物细胞维持离子平衡中的关键作用受到了人们越来越多的关注。结合前人的研究结果和最新的研究动态,着重阐述了Na+转运控制和维持细胞离子平衡在植物耐盐过程中的机理及其重要作用。     

中国环境污染损失测算及成因探析

环境问题备受关注,环境污染严重影响中国经济的增长质量.本文采用治理成本法测算了1989 -2008年中国环境污染造成的经济损失,利用环境污染经济损失数据,采用协整理论研究了中国环境污染损失与经济增长之间的关系.研究表明,我国经济总量与环境污染之间存在长期均衡关系,经济增长是造成环境污染的基础性原因,并且环境污染状况随经济增长仍有扩大的趋势,至今尚未出现环境库兹涅茨曲线拐点的迹象.然后,本文从产业结构、能源结构和效率角度揭示了环境污染的结构性成因.研究认为,高污染行业在整个国民经济中比重过大是造成环境污染的产业结构方面的成因;以煤炭为主的能源消费和高耗能产品增长过快是造成环境污染的能源结构成因;能源效率低下是造成环境污染的技术性成因;资源能源价格长期偏低和法律法规滞后是造成环境污染的制度性缺陷.最后,针对问题提出,只有切实转变经济增长方式,突出技术创新、健全市场机制、完善环境法规才是解决环境污染问题的根本出路.     

Developments in greenhouse gas emissions and net energy use in Danish agriculture - how to achieve substantial CO(2) reductions?

Greenhouse gas (GHG) emissions from agriculture are a significant contributor to total Danish emissions. Consequently, much effort is currently given to the exploration of potential strategies to reduce agricultural emissions. This paper presents results from a study estimating agricultural GHG emissions in the form of methane, nitrous oxide and carbon dioxide (including carbon sources and sinks, and the impact of energy consumption/bioenergy production) from Danish agriculture in the years 1990–2010. An analysis of possible measures to reduce the GHG emissions indicated that a 50–70% reduction of agricultural emissions by 2050 relative to 1990 is achievable, including mitigation measures in relation to the handling of manure and fertilisers, optimization of animal feeding, cropping practices, and land use changes with more organic farming, afforestation and energy crops. In addition, the bioenergy production may be increased significantly without reducing the food production, whereby Danish agriculture could achieve a positive energy balance.     

大力发展循环经济促进碳循环和碳汇产业发展

介绍了碳循环与碳汇产业的科学内涵及其在我国的发展现状与目标,提出“十二五”期间应大力推广的几种碳循环与碳汇产业的成功模式,以及促进碳循环和碳汇产业发展的对策建议。     

Timekeeping in the honey bee colony: integration of circadian rhythms and division of labor

The daily patterns of task performance in honey bee colonies during behavioral development were studied to determine the role of circadian rhythmicity in age-related division of labor. Although it is well known that foragers exhibit robust circadian patterns of activity in both field and laboratory settings, we report that many in-hive tasks are not allocated according to a daily rhythm but rather are performed 24 h per day. Around-the-clock activity at the colony level is accomplished through the performance of some tasks by individual workers randomly with respect to time of day. Bees are initially arrhythmic with respect to task performance but develop diel rhythmicity, by increasing the occurrence of inactivity at night, prior to becoming foragers. There are genotypic differences for age at onset of rhythmicity and our results suggest that these differences are correlated with genotypic variation in rate of behavioral development: genotypes of bees that progressed through the age polyethism schedule faster also acquired behavioral rhythmicity at an earlier age. The ontogeny of circadian rhythmicity in honey bee workers ensures that essential in-hive behaviors are performed around the clock but also allows the circadian clock to be engaged before the onset of foraging. Received: 6 October 1997 / Accepted after revision: 28 March 1998     

The role of age in temporal polyethism in a primitively eusocial wasp

The relation of age to division of labor was assessed in a primitively eusocial wasp, Ropalidia marginata. The performance of four functionally significant tasks was analyzed. It was found that age has a definite correlation with division of labor, since wasps performed tasks in a distinct sequence in their life with successive tasks being initiated at significantly older ages. Age of a wasp was measured in absolute terms and also relative to other individuals in the colony. Probability of performance of a given task relative to other tasks (PTP) and absolute rates at which tasks were performed per unit time (FTP) both showed clear age-dependent patterns, confirming the association of age with division of labor. The proportion of variance explained for both PTP and FTP was significantly higher with relative age than with absolute age. Interindividual interactions were found to be a potential mechanism through which wasps can determine their relative age. The advantages of work organization depending on relative age and the constraints imposed by absolute age are discussed. Received: 2 April 1997 / Accepted after revision: 20 July 1997     

基于电阻率的硫酸污染水泥土检测方法的探讨

电阻率法作为一种简单有效的测试方法,已在岩土工程检测中得到了一定程度的应用.通过室内试验模拟了水泥土试块受不同浓度硫酸溶液污染的反应,采用电阻率法研究了孔隙水电阻率、水泥土电阻率、结构因子与溶液浓度和龄期之间的关系.结果表明,孔隙水和水泥土电阻率随溶液浓度增大而减小、随龄期的增大而增大,结构因子随着溶液浓度和龄期的增加而增加,它们之间具有较高的相关性.这充分说明,电阻率法可应用于硫酸污染水泥土的检测和评价.     

加速碳酸化技术对城市垃圾焚烧飞灰重金属稳定性影响研究

对南方某城市生活垃圾焚烧厂新鲜焚烧飞灰对CO₂的吸收及其碳酸化的过程进行了研究,实验从水分添加量、CO₂的分压等因素,考察了飞灰中重金属Pb的稳定化效果,并利用X射线衍射实验(XRD)、扫描电镜实验(SEM)对反应机理进行了分析.结果表明,不添加水分时,焚烧飞灰对CO₂的吸收效果较差;当水分添加量大于10％时,焚烧飞灰对CO₂的吸收效果较好.焚烧飞灰对纯CO₂的吸收效果较好,空气中的CO₂含量较低,在反应1 d后吸收效果不是十分明显.XRD实验结果表明,CO₂的吸收会使焚烧飞灰中大量的Ca(OH)₂与CO₂反应转化为CaCO₃,从而降低焚烧飞灰的碱性;部分重金属的氧化物会被碳酸化成生相应的碳酸盐.SEM实验结果表明,经过碳酸化处理后的飞灰颗粒表面生成了片状和圆柱状的晶体物质.