土壤重金属的植物污染化学研究进展

针对中国土壤重金属污染加剧的趋势,为改善土壤环境质量和保障农产品安全,提出了土壤重金属的植物污染化学研究领域.结合多年的研究工作,从土壤重金属的植物根际化学行为、土壤重金属的植物吸收与解毒机制和重金属污染土壤的植物-微生物交互作用等方面简要阐述了土壤-植物系统中重金属的分布、存在形态、迁移转化、累积及生物学效应和控制规律的研究进展,并对将来的植物污染化学理论研究提出了展望.     

江苏省耕地资源利用中存在的问题及对策探讨

根据《江苏统计年鉴 (1 999)》等相关资料 ,对江苏耕地资源利用中存在的一些问题进行了分析与总结 ,在此基础上 ,对实现江苏耕地资源可持续利用的相关对策进行了探讨     

贵州喀斯特土石山区水土保持生态经济型植被恢复模式

以贵州省喀斯特土石山区为例,通过总结前人的研究成果和中国科学院亚热带农业生态研究所喀斯特生态实验站的部分试验数据,从全局性、紧迫性、高效性、层次性、可持续性、创新性与多样性的角度提出了在贵州喀斯特土石山区的急坡地、陡坡地、缓陡坡地其水土保持生态经济型植被恢复模式分别采用3种典型模式,即:灌草模式,乔灌草模式与林果模式,以期促进该区域的生态、经济与社会的全面协调与可持续发展。     

基于数量化理论Ⅱ的鄂西北山区坡面土壤侵蚀强度评价

水土流失既是资源问题，又是生态环境问题。土壤侵蚀对人类生存和发展构成了严重威胁，成为制约可持续发展的障碍因素。以鄂西北丹江口库区郧西县坡面径流小区为试验点，通过分析小区的实地观测数据，建立坡面土壤侵蚀定性评价指标体系，并将数量化理论II作为有效的数学方法，建立郧西县坡面径流小区土壤侵蚀强度评价模型，对参与建立模型的样本进行回归分析，其准判率达到800%以上，并且利用该模型对其他年份坡面土壤侵蚀强度实测数据进行对比验证，得到土壤侵蚀强度分级的精度较高。研究表明，建立的郧西县坡面径流小区土壤侵蚀强度评价模型有较好的适用性与可靠性，可为郧西县及类似自然地理环境的其他区域水保工作起到一定指导意义     

刚性桩复合地基的理论、实测与安全性研究

科学合理的设计理论是工程安全性和经济性的保障，现场监测是确保工程安全和质量最有效的手段。本文以提高刚性桩复合地基工程的安全性为目的，围绕关乎建筑物安全的“沉降量”等参数指标，从设计理论与试验监测两个方面开展研究。本文完善了刚性桩复合地基的设计理论，通过现场监测试验取得了第一手的数据资料，可作为今后类似工程的设计和施工参考。本研究为进一步提高刚性桩复合地基的安全性提供了理论和实践保障。     

Comparison of Point Estimation Techniques in the Spatial Analysis of Radium-226, Radium-228 and Potassium-40 in Soil

Many environmental surveys require the implementation of estimation techniques to determine the spatial distribution of the variable being investigated. Traditional methods of interpolation and estimation, for example, inverse distance squared and triangulation often ignore features of the data set such as anisotropy which may have a significant impact on the quality of the estimates produced. Geostatistical techniques may offer an improved method of estimation by modelling the spatial continuity of the variable using semi-variogram analysis. The theoretical model fitted to the semi-variogram is then used in the assignation of weighting factors to the samples surrounding the location to be estimated. This paper outlines the results of a comparison between three common estimation methods, polygonal, triangulation and inverse distance squared and a geostatistical method, in the estimation of soil radionuclide activities. The geostatistical estimation method known as kriging performed best over a range of parameters used to test the performance of the methods. Kriging exhibited the best correlation between actual and estimated values, the narrowest error distribution and the lowest overall estimation error. Polygonal estimation was best at reproducing the data set distribution. Conditional bias was evident in all the methods, low values being over-estimated and high values being under-estimated.     

Correlation of foliar MT2b expression with Cd and Zn concentrations in hybrid aspen (Populus tremula × tremuloides) grown in contaminated soil

Metal uptake and its effect on foliar metallothionein 2b (MT2b) mRNA levels were studied in hybrid aspen (Populus tremula × tremuloides) in field conditions. The trees were planted on a site contaminated with several metals, including cadmium (mean 5.1 mg kg⁻¹), chromium (80 mg kg⁻¹), copper (180 mg kg⁻¹), nickel (81 mg kg⁻¹), vanadium (240 mg kg⁻¹) and zinc (520 mg kg⁻¹). Of the ten trace elements analyzed, only Cd and Zn accumulated in the leaves with maximal foliar concentrations of 35 and 2400 mg kg⁻¹ (dry weight), respectively. There was a strong correlation between Cd and Zn concentrations and bioaccumulation factors (concentration in plant/soil) in the leaves, branches and roots, suggesting similar transport mechanisms for these two metals. The levels of MT2b correlated with Cd and Zn concentrations in the leaves, demonstrating that increased MT2b expression is one of the responses of hybrid aspen to chronic metal exposure.     

Soil Contribution to the Elemental Composition of Epiphytic Lichens (Tuscany, Central Italy)

Total concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Sr, Ti, V and Zn in the epiphytic lichen Parmelia sulcata and superficial soils from 60 remote sampling sites in Tuscany (central Italy) were determined to evaluate the contribution of soil to the elemental composition of the lichen. The results showed that in the Mediterranean environment, the trace element content of unwashed lichen samples is greatly affected by soil contamination. However, despite the strong correlations between the concentrations of lithogene elements such as Al, Fe and Ti in P. sulcata, lichen levels of these elements were not at all linearly correlated with their concentrations in the soil, suggesting that dust contamination is highly variable and probably dependent on local site characteristics. All methods evaluated to minimize soil contamination indicated Cu, Pb and Zn as elements of atmospheric origin. However, while levels of Pb were similar to those reported for background areas, moderate pollution by Cu and Zn, probably from fertilizers used in agriculture, was revealed. For elements such as Cd and Mo, identified as atmophile, some uncertainty exists due to the fact that they are essential for lichen metabolism and accumulate intracellularly in lichens; they may therefore occur in soluble form in the lichen thallus.     

中国省域违法占用耕地的空间效应

要通过中国省域违法占用耕地的时空特征分析,得知1999-2007年中国违法占用耕地均值的空间布局总体较为离散,局部地区表现出集聚态势；运用空间计量分析方法,对1999-2007年间中国各省域违法占用耕地的空间效应研究表明,中国大陆31个雀域的违法占用耕地在地理空间上存在显著的正自相关关系,表现出了某些省域违法占用耕地的相似性在空间上趋于集聚现象,1999-2007年中国违法占用耕地的省域空间集聚近似呈现“N”字型波动变化的态势.中国违法占用耕地省域之间正的空间效应正在增强,中国省域违法占用耕地存在地理空间的邻近效应.     

西庄河流域土地利用方式对土壤肥力影响的研究

采用野外调查、取样和实验分析相结合的方法对云南省保山市西庄河山地流域内4种主要土地利用方式（林地、耕地、茶园、灌丛）的土壤理化性质进行对比研究，讨论了不同土地利用方式对土壤肥力的影响，结果表明，不同的土地利用方式对土壤肥力具有比较明显的影响：土壤有机质和全氮质量分数变化从大到小依次为灌丛＞林地＞茶园＞耕地；磷、钾元素表现为耕地＞茶园＞林地＞灌丛；土壤阳离子交换量表现为耕地＞茶园＞灌丛＞林地；盐基饱和度表现为耕地＞灌丛＞林地＞茶园；农业耕作活动对表层土壤物理性质影响明显。