采用物理指标评价黏性土承载力的方法研究

利用大连长兴岛葫芦山湾海域勘察资料,对742组黏性土的主要物理指标与承载力fo的对比数据,进行了相关分析。建立了黏性土主要物理指标与承载力fo之间经验关系4个。提出了实际勘察工作中承载力特征值fak的评价方法,为利用物理指标评价黏性土承载力建立了理论基础。     

Effect of vegetation with different evolution degree on soil organic matter in a semi-arid environment (Cabo de Gata-Níjar Natural Park, SE Spain)

The organic matter of the surface horizons of soils developed below scrub vegetation in a Mediterranean semi-arid area of great environmental interest (Cabo de Gata-Níjar Natural Park, SE Spain) has been studied. The study mainly concentrates on examining the influence of two vegetation types, one evolved (according to its successional stage), and the other clearly degraded as a result of prior removal of vegetation. In spite of the homogeneity in the results obtained from the analysis of the organic matter from the soils studied, a relationship may be established between vegetation biotype and characteristics and evolution of the soil organic matter. The evolved vegetation results in the presence in the soil of a somewhat more evolved and stable organic matter (demonstrated by certain chemical and microbiological aspects), resulting in a greater degree of humification, thus favouring the protection of the soil and the ecosystem as a whole. Hence, the presence of degraded vegetation might lead to soil degradation, something that is unsustainable in semi-arid areas that are particularly fragile in nature.     

Revisiting Sustainable Development of Dry Valleys in Hengduan Mountains Region

Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated mainly on rehabilitation of degraded ecosystem and fragile environment, particularly reforestation, while socio-economic development has been largely overlooked. Despite successes in pocket areas, the overall trend of unsustainability and environmental deterioration are continuing. It is important to understand that uplift of the Tibetan Plateau is the root cause of development of dry valleys, and development and formation of dry valleys is a natural process. Human intervention has played a secondary role in development of dry valleys and degradation of dry valleys though human intervention in many cases has speeded up environmental degradation of the dry valleys. It is important to understand that dry valleys are climatic enclaves and an integrated approach that combines rehabilitation of degraded ecosystems and socio-economic development should be adopted if the overall goal of sustainable development of dry valleys is to be achieved. Promotion of niche-based cash crops, rural energy including hydropower, solar energy, biogas and fuelwood plantation is recommended as the priority activities.     

Evaluation of heavy metal contamination and implication of multiple sources from Hunchun basin, northeastern China

Present concentrations and distributions of heavy metals through profiles, surface soil, and stream sediment samples in the Hunchun area, north-eastern China, were investigated to determine the elemental background values. This study also aims to characterize potentially toxic materials such as pulverized fly ash (PFA) from power stations or ash and slag from coal used domestically in urban areas, agrochemicals applied inappropriately, and urban sewage sludges from Hunchun City, as well as to ascertain the possibility of natural enrichment through site characterization by mineralogical and geochemical investigation. The distribution of contaminants in the alluvial soils (fluvisol) of this area has been influenced by several interacting factors. The parent alluvial materials from weathered products of amphiboles have made coatings such as ferrihydrite, goethite, and hematite. This natural inheritance factor is supported by the fact that the concentrations of weak acid-extractable (plant-available) heavy metals are very low, except for Fe and Mn. However, in agricultural soils and adjacent stream sediments, an anthropogenic input of Cd, Pb, Ni and Cr by agrochemicals is strongly suggested. Also, F contamination by coal combustion and the dissolution of F-bearing minerals could cause some future problems. Wide distribution and significantly high concentrations of Cd, Fe, Mn, and F in soils throughout the combination of pollutants originating from lithogenic and the anthropogenic sources pose potential problems in utilizing water resources. Received: 14 June 1999 · Accepted: 27 December 1999     

基于HJ-1A高光谱影像的湿地精细分类

混合像元的存在不仅影响了基于高光谱影像的地物识别和分类精度,而且已成为遥感科学向定量化发展的主要障碍。本文以扎龙湿地为试验区,以环境一号卫星采集的高光谱影像为数据源,分别采用传统的全约束最小二乘光谱解混算法(fully constrained least squares spectral unmixing algorithm, FCLS)与基于稀疏约束最小二乘光谱解混算法(sparse constrained least squares spectral unmixing algorithm, SUFCLS)实现了试验区湿地的精细分类,并对两种分类结果的表现及其分类精度进行了对比分析。研究结果表明：SUFCLS算法能够自适应的从光谱库中选择场景中所占比例最高的一组端元,并将此端元的组合应用于传统的全约束最小二乘光谱解混中实现不同湿地类型丰度的提取,该算法充分考虑了端元的空间异质性,弥补了FCLS算法在端元选取过程中的不足。精度验证结果表明与FCLS算法相比,SUFCLS算法分类结果的均方根误差更小,丰度的相关系数更高,因此该方法对于提高湿地解混精度以及实现湿地精细化分类具有重要意义。     

控制论与人工影响天气II.工程控制论在人工增雨作业中的应用与建模

人工增雨已有60余年历史,虽已取得很多成绩,仍存在很多亟待解决的科学技术问题,典型问题如作业具有一定的主观性及其与效果检验有脱节.控制论研究如何对系统施加控制作用使其表现出预定行为.作者研究工程控制论在人工增雨作业中的应用与建模问题,将工程控制论引入人工增雨作业,称作“局部控制”方法.以冷云的人工催化过程为例,以单容加延迟的过程来简化单块冷云催化核化过程,建立了有反馈的冷云催化框架模型.根据效果调整催化剂的播撒率以实施控制作用,使作业后的雨云关键参数达到预期值.这种“局部控制”方法,可使现有作业更科学化和客观定量化,只在作业设备中增加一通讯单元和作为传感/变送器以及控制器的一套专业软件即可.“局部控制”方案也可嵌入以自然控制论为框架的大范围全面全程控制问题中,简化作业的方案.     

Geochemical distribution and removal of As,Fe, Mn and Al in a surface water system affected by acid mine drainage at a coalfield in Southwestern China

The chemical characteristics, formation and natural attenuation of pollutants in the coal acid mine drainage (AMD) at Xingren coalfield, Southwest China, are discussed in this paper based on the results of a geochemical investigation as well as geological and hydrogeological background information. The chemical composition of the AMD is controlled by the dissolution of sulfide minerals in the coal seam, the initial composition of the groundwater and the water–rock interaction. The AMD is characterized by high sulfate concentrations, high levels of dissolved metals (Fe, Al, Mn, etc.) and low pH values. Ca²⁺ and SO₄ ²⁻ are the dominant cation and anion in the AMD, respectively, while Ca²⁺ and HCO₃ ⁻ are present at significant levels in background water and surface water after the drainage leaves the mine site. The pH and alkalinity increase asymptotically with the distance along the flow path, while concentrations of sulfate, ferrous iron, aluminum and manganese are typically controlled by the deposition of secondary minerals. Low concentrations of As and other pollutants in the surface waters of the Xingren coalfield could be due to relatively low quantities being released from coal seams, to adsorption and coprecipitation on secondary minerals in stream sediments, and to dilution by unpolluted surface recharge. Although As is not the most serious water quality problem in the Xingren region at present, it is still a potential environmental problem. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

频率域偶层位曲面位场处理和转换方法研究

在空间域偶层位法的基础上,研究了完整的频率域偶层位曲面位场处理和转换方法.该法可应用于平面或曲面、规则网或非规则网的位场数据处理和转换.通过对偶层面z坐标和计算面z坐标平移不同的量来加速正演快速收敛和保证反演稳定、快速收敛;提出了适合于不规则网曲面处理和转换的核心算法——单点快速Fourier变换;提出了频率域不规则网曲面处理和转换方法技术.通过以上技术措施解决了大数据量特别是曲面不规则网的位场处理和转换问题,模型试算以及实际资料处理验证了该方法的应用效果.     

国家自然科学基金资助体系下的地下水科学领域发展总结和分析

地下水属于基础性、战略性水资源,其科学开发利用和保护关系到人类社会与生态系统的协同健康发展。因此,地下水一直是自然科学关注的热点和焦点之一。笔者统计分析了1986~2022年期间国家自然科学基金委对地下水科学领域的资助情况,从受资助项目的学部学科分布、项目类型和主要研究方向入手,总结了地下水科学研究现状,揭示了目前存在的短板和瓶颈问题,并分析了地下水科学发展趋势。研究结果表明：①地下水科学领域资助项目的数量和类型均呈快速增长态势;②地下水科学领域与其他学科领域的交叉融合越来越频繁、紧密,涉及多个学部和学科,申报与资助均呈现“多点开花”态势;③地下水科学作为地球科学的分支学科,面临新的机遇和挑战,许多重大科学问题亟待解决,需进一步提高重大项目支持力度;④地下水科学研究具备与更多相关领域交叉渗透的潜力,如海洋学、化学、气象学和大气科学等,国家自然科学基金委可为地下水科学与其他学科交叉提供培育平台。     

Reducing hazard vulnerability through local government engagement and action

The concept of a natural hazard is a human construct. It is the interaction with human communities and settlements that defines a natural phenomenon as a natural hazard. Thus the end point of hazard mitigation and hazard vulnerability assessment must involve an attempt to reduce, or mitigate, the impact of the natural hazard on human communities. The responsibility to mitigate hazard impact falls primarily upon governments and closely connected non-government and private institutional agencies. In particular, it is most often local government that takes the responsibility for safeguarding its own communities, infrastructure and people. Hazard vulnerability of specific local communities is best assessed by the local government or council, which then faces the responsibility to translate that assessment into community education and infrastructural safeguards for hazard mitigation. This paper illustrates the process of local government engagement in hazard mitigation in Australia, through the Natural Disaster Risk Management Studies, as a first step towards natural disaster reduction.