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81.
土壤侵蚀是全球性的环境问题之一,严重威胁到资源、环境和社会经济的可持续发展。应用核素示踪技术研究土壤侵蚀已成为当前该领域研究热点,它体现出了很多的优越性,并在今后研究中有着广阔的应用前景。本文介绍了210Pbex的示踪原理,概述了210Pbex在土壤侵蚀示踪研究中的存在的关键性问题及其应用,并对其研究进行了展望。  相似文献   
82.
以长岛县南五岛土壤为研究对象,对区内土壤元素的含量特征进行分析,并对土壤环境质量进行评价。结果表明:研究区土壤平均含量与烟台市、山东省以及全国土壤平均水平相比,除CaO,Na2O,Hg,S,Se,P,F元素含量差异较明显,其他大部分元素含量相对稳定,元素含量的高低不仅与研究区背景条件有关,也与人类活动密切相关。研究区土壤环境质量整体较好,大部分区域属于清洁区和尚清洁区,仅城区局部受到一定程度的Cd,Hg,Zn污染。  相似文献   
83.
孙霞  谭微  贾双琳  杨刚  周小林 《贵州地质》2018,35(3):257-261
介绍了用微波消解处理土壤和水系沉积物样品,用电感耦合等离子质谱仪(ICP-MS)快速高效测试碘的方法。方法的检出限为0. 012μg/g。所选的12个土壤和水系沉积物国家一级标准物质12次测定,除GBW07307a的RSD小于10%外,其余RSD值均小于5%,12次测试的平均值和标准值对数差绝对值均小于0. 05。方法加标回收率在98. 6%104. 6%之间。  相似文献   
84.
Revised Universal Soil Loss Equation(RUSLE) model coupled with transport limited sediment delivery(TLSD) function was used to predict the longtime average annual soil loss, and to identify the critical erosion-/deposition-prone areas in a tropical mountain river basin, viz., Muthirapuzha River Basin(MRB; area=271.75 km~2), in the southern Western Ghats, India. Mean gross soil erosion in MRB is 14.36 t ha~(-1) yr~(-1), whereas mean net soil erosion(i.e., gross erosion-deposition) is only 3.60 t ha~(-1) yr~(-1)(i.e., roughly 25% of the gross erosion). Majority of the basin area(~86%) experiences only slight erosion(5 t ha~(-1) yr~(-1)), and nearly 3% of the area functions as depositional environment for the eroded sediments(e.g., the terraces of stream reaches, the gentle plains as well as the foot slopes of the plateau scarps and the terrain with concordant summits). Although mean gross soil erosion rates in the natural vegetation belts are relatively higher, compared to agriculture, settlement/built-up areas and tea plantation, the sediment transport efficiency in agricultural areas and tea plantation is significantly high,reflecting the role of human activities on accelerated soil erosion. In MRB, on a mean basis, 0.42 t of soil organic carbon(SOC) content is being eroded per hectare annually, and SOC loss from the 4th order subbasins shows considerable differences, mainly due to the spatial variability in the gross soil erosion rates among the sub-basins. The quantitative results, on soil erosion and deposition, modelled using RUSLE and TLSD, are expected to be beneficial while formulating comprehensive land management strategies for reducing the extent of soil degradation in tropical mountain river basins.  相似文献   
85.
Multiple types of responses, such as displacements, ground water level, pore water pressures, water contents, etc., are usually measured in comprehensive monitoring programmes for rainfall-induced landslide prevention. In this study, a probabilistic calibration method for coupled hydro-mechanical modelling of slope stability is presented with integration of multiple types of measurements. A numerical example of a soil slope under rainfall infiltration is illustrated to compare the effects of single and multiple types of responses on parameter estimation and model calibration. The results show that the soil parameters can be estimated with less uncertainty and total uncertainty bounds are narrower with multiple types of responses than with a single type of response. Model calibration based on multiple types of responses can compromise different responses and hence the means and standard deviations of model error are the smallest. A feasible correlation coefficient between soil modulus and permeability can be obtained from model calibration with multiple types of responses and single type of response as long as the responses include displacement data.  相似文献   
86.
Salinization is one of the major soil degradation threats occurring worldwide. This study evaluates the feasibility of operational surface soil salinity mapping based on state-of-the-art Earth Observation (EO) products captured by sensors on-board WorldView-2 (WV2) and Landsat 8 satellites. The proposed methods are tested in Timpaki, south-central Crete,Greece, where brackish water irrigation puts soil health at risk of soil salinization. In all cases, EO products are calibrated against soil samples collected from bare soil locations. Results indicate a moderate correlation of observed ECe values with the investigated remote sensing parameters. Regarding sensitivity to saline soil, the yellow band displays higher values. Comparison between methods used in the literature shows that those developed specifically for soil salinity, and especially index S5, perform better. The proposed ‘detection index’ and 3D PCA transformation methodology perform reasonably well in detecting areas with high ECe values and provide a simple and effective operational alternative for saline topsoil detection and mapping.  相似文献   
87.
Detecting soil salinity changes and its impact on vegetation cover are necessary to understand the relationships between these changes in vegetation cover. This study aims to determine the changes in soil salinity and vegetation cover in Al Hassa Oasis over the past 28 years and investigates whether the salinity change causing the change in vegetation cover. Landsat time series data of years 1985, 2000 and 2013 were used to generate Normalized Difference Vegetation Index (NDVI) and Soil Salinity Index (SI) images, which were then used in image differencing to identify vegetation and salinity change/no-change for two periods. Soil salinity during 2000–2013 exhibits much higher increase compared to 1985–2000, while the vegetation cover declined to 6.31% for the same period. Additionally, highly significant (p < 0.0001) negative relationships found between the NDVI and SI differencing images, confirmed the potential long-term linkage between the changes in soil salinity and vegetation cover.  相似文献   
88.
A comparative study of soil erosion modelling by MMF,USLE and RUSLE   总被引:1,自引:0,他引:1  
The quantitative assessment of spatial soil erosion is valuable information to control the erosion. The study area in a part of Narmada river in central India is selected. The main objective is to assess and compare the results obtained from three soil erosion models using GIS platform. Variation in the rate of erosion of the three models is compared considering varying slope, soil and land use of the area. Three models selected are Morgan–Morgan–Finney (MMF), Universal Soil Loss Equation (USLE) and Revised Universal Soil Loss Equation (RUSLE). The best fit or the most reliable model for the study area is selected after validation with the observed sedimentation data. The results give –39.45%, –9.60% and 4.80% difference in the values of sedimentation by MMF, USLE and RUSLE, respectively, from the observed data. Finally, RUSLE model has been found to be most reliable for the study area.  相似文献   
89.
利用反射GPS信号遥感土壤湿度   总被引:5,自引:0,他引:5  
在水文、气候、农业等问题的研究中,土壤湿度信息十分重要。近年来,利用GPS系统进行遥感的新方法,已经越来越多地引起研究者们的关注。特别是GPS卫星广播的L1(1.57542GHz)频率信号,是土壤湿度遥感的最佳频率。反射GPS信号功率是土壤介电常数的函数,而土壤介电常数又和土壤湿度有关。根据这一原理,美国国家航空与航天局于2002年进行了基于地表面反射GPS信号的遥感土壤湿度实验。结果证明反射GPS信号对土壤湿度特性十分敏感,由于植被的影响对反射率进行了修正,并用此方法模型与其它方法进行了比较。在利用GPS遥感土壤湿度方面,研制高增益天线,更好的修正信号波动的影响,发展更加完善的遥感土壤湿度方法等是今后在此项研究中所要解决的问题。  相似文献   
90.
中国土壤有机质含量变异性与空间尺度的关系   总被引:28,自引:0,他引:28  
以中国土种志资料为基础,分析了土壤有机质含量变异与空间尺度的关系及土类内和土类间的变异程度,探讨了不同空间尺度单元下,土壤有机质平均含量与土壤性质的相关性。结果表明,以土壤剖面为单元,随着土壤剖面数的增加,土壤有机质含量的变异系数增大;行政区域尺度单元内部土壤有机质变异程度大于单元间土壤有机质含量的变异程度。以土壤分类单元为空间单元,土类内的有机质含量变异程度小于土类间的变异程度。随着统计单元空间尺度的增大,土壤有机质含量与土壤性质之间的相关性减弱。因此,采用网格法或行政区划分空间区域,获得空间区域单元内土壤有机质含量或贮量的精确估算需要较多的剖面,但外推至数据不足的空间区域时,估算的不确定较小;采用土壤分类单元为空间区域单元,结果则相反。  相似文献   
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