共查询到18条相似文献,搜索用时 64 毫秒
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137Cs示踪法研究青藏高原草甸土的土壤侵蚀 总被引:5,自引:0,他引:5
运用137Cs示踪法对青藏高原高寒草甸典型的两个小流域的土壤侵蚀进行了研究,结果表明:高寒草甸植被区的土壤137Cs在土壤剖面中呈指数型分布,分布深度一般在20cm左右;坡顶部由于风蚀、冻融侵蚀和水蚀较强,致使侵蚀强于下部,除坡顶部外其他坡位侵蚀强度都符合坡上部<坡中部<坡下部的规律;高寒草甸植被覆盖度与土壤侵蚀强度呈显著的负相关关系(p<0.01),土壤平均侵蚀模数随植被覆盖度的增加呈线性降低的趋势,相关系数R2达到0.997以上。高寒草甸退化程度越高,土壤侵蚀越强。退化较强的草甸区的平均侵蚀模数是退化较弱区的2.23倍,最大侵蚀模数可达2960.22t/(km2.a)。 相似文献
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137Cs法在风沙过程研究中的应用前景 总被引:6,自引:3,他引:3
137Cs法在土壤侵蚀与泥沙沉积研究中已得到普遍的应用,但在风沙过程研究中尚未引起足够的重视。针对风沙过程研究中存在的有关问题,对137Cs法的应用前景作了展望,并提出了137Cs应用的若干建议。 相似文献
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在黔南峰丛洼地区林间白云岩坡地应用137Cs法研究土壤侵蚀。4个坡面采样样方的137Cs面积浓度都低于137Cs本底值浓度;表土样137Cs浓度随着坡长增加而增大,全样137Cs面积浓度的顺坡变化呈逐步下降趋势;应用137Cs农耕地侵蚀模型计算获得样点土壤侵蚀量后,加以坡长加权平均计算获得的坡长权重土壤位移量为2.045 t/(km2·a)。同时在坡脚的土壤分层剖面中的137Cs浓度峰值在土壤次表层出现,随着深度增加呈指数递减变化,属于未受耕作扰动的无侵蚀非农耕地,但表层含有相对低浓度137Cs是坡面侵蚀泥沙的搬运堆积结果,估算距1963年以来侵蚀泥沙年平均堆积厚度为0.0682~0.1364 cm/a。坡地土壤侵蚀速率远小于以往贵州喀斯特地区典型喀斯特小流域和坡地的观测结果,但坡脚泥沙堆积速率远大于坡地土壤侵蚀速率。表明季节性暴雨、坡面降雨汇流和耕作侵蚀等侵蚀作用使喀斯特坡地土壤颗粒出现微距离位移,长期则在坡脚出现显著的侵蚀泥沙堆积。 相似文献
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青海共和盆地土壤风蚀的137Cs法研究(Ⅰ)——137Cs分布特征 总被引:2,自引:1,他引:2
土壤风蚀作为土地沙漠化的首要环节,对其准确测定和评估是十分迫切和必要的。放射性核素137Cs作为人类核试验的产物,以其独特的理化性质而成为研究土壤侵蚀和泥沙沉积一种良好的示踪源。137Cs法在水蚀研究领域已取得了显著的进展,而在风蚀研究中的应用却相对不足,目前尚处于探索阶段。作者选择青海共和盆地作为研究区,探讨137Cs法在土壤风蚀研究中应用的可行性。通过对共和盆地不同类型土壤剖面的137Cs取样分析,基本查清了区域137Cs分布的若干特性,测定出不同类型土地137Cs活度的排序为:林地>干湖盆>高寒草原>旱作农田≈干草原>固定沙丘>荒漠草原>流动沙丘>风蚀地,137Cs总量的排序为:干湖盆>林地>流动沙丘>高寒草原>旱作农田≈干草原>固定沙丘>荒漠草原>风蚀地。并分析了一些典型剖面的137Cs深度分布及其机制,将137Cs深度剖面划分为正常剖面、沉积剖面、侵蚀剖面和人为扰动剖面4种型式。沙丘砂由于遭受反复吹失和沉积,其137Cs含量逐渐减小,趋于微量的均匀化;而高寒草原的137Cs含量在区域上也较为均匀,在深度分布上,接近负指数分布曲线保存了相对完好的137Cs初始沉积剖面,是理想的137Cs背景值样点。 相似文献
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通过137Cs示踪技术,并采用土壤剖面核素单位面积浓度与背景值之间的理论模型,对布哈河下游和青海湖东北岸湟水上游区域的土壤侵蚀进行了研究,结果表明:137Cs面积活度与植被盖度之间存在着正相关关系,两区域相关系数为0.93。湟水上游河谷土壤侵蚀模数在87.62~1 458.41 t·km-2·a-1之间,采样点平均土壤侵蚀模数为933.31 t·km-2·a-1。布哈河下游区域土壤侵蚀模数在431.03~2 072.39 t·km-2·a-1之间,采样点平均土壤侵蚀模数为1 256.97 t·km-2·a-1。布哈河下游区域较湟水上游区域侵蚀严重,在较长的时期内两地大部分区域均处于轻度侵蚀阶段,湟水上游北部和布哈河下游西北部处于微度侵蚀阶段。 相似文献
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基于137Cs计年法估算滇池沉积物重金属负荷 总被引:5,自引:5,他引:0
根据滇池流域地貌、湖盆形态、物源供给等,用GIS方法将滇池外海分作7个区域,以137Cs计年法确定各区域上部沉积物3个沉积时段为1954~1963、1963~1986、1986~2003年,测算不同时段各区域的泥沙年均沉积通量和年均蓄积量,与当地实情及他人用其它方法研究对照,结果可以吻合。在此基础上,结合实验室测量,估算各区域的Cu、Cr、Cd、Pb、Hg、Zn在各时段的年均沉积通量,得到1963~2003年期间滇池沉积物几种重金属负荷分别达到1040.8、1054.0、11.2、824.7、2.5、2465.6 t。故应十分重视滇池沉积物中重金属,采用减少重金属和泥沙入湖量并举的措施控制沉积物重金属负荷的进一步增长。 相似文献
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高寒草甸是青藏高原主要的草地类型之一。为了解高寒草甸坡面土壤侵蚀特征,以兴海盆地高寒草甸坡面为研究区,分析了高寒草甸坡面上 137Cs和 210Pbex的分布特征;利用 137Cs和 210Pbex示踪方法,通过转换模型估算了高寒草甸坡面土壤侵蚀速率,并对两种方法估算的结果进行了对比。结果表明:(1)选取的高寒草甸背景土壤剖面上 137Cs质量活度最大值分布在 2~4 cm层位, 210Pbex质量活度最大值出现在最表层。(2)研究区坡面 137Cs和 210Pbex质量活度和通量在不同的坡位有明显的差异。(3)根据 210Pbex估算的土壤侵蚀速率高于基于 137Cs估算的土壤侵蚀速率,表明研究区近几十年土壤侵蚀可能呈增加趋势。(4)根据 137Cs和 210Pbex估算的土壤侵蚀速率具有极显著的正相关关系( r = 0.94,P < 相似文献
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岩溶坡地土壤侵蚀强度的137 Cs法研究 总被引:14,自引:0,他引:14
在重庆南部南川市境内,按不同侵蚀强度取137Cs样品,用于研究岩溶坡地不同侵蚀程度的土壤侵蚀强度与特征。结果表明,林草地侵蚀速率变化范围49.3 t/(km2.a)~230.5 t/(km2.a),平均侵蚀速率112.5 t/(km2.a);缓坡耕地侵蚀速率变化范围190.3~1 138.4 t/(km2.a),平均565.5 t/(km2.a);陡坡耕地的侵蚀速率变化范围为452.0~3 759.4 t/(km2.a),平均2 264.8 t/(km2.a)。与黄土高原和紫色土区相比,岩溶区侵蚀速率较小。 相似文献
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Ava D. Simms Colin Woodroffe Brian G. Jones Henk Heijnis Jennifer Harrison Rob A. Mann 《The Australian geographer》2008,39(4):445-465
Soil redistribution studies are important, especially in water supply catchments, because the rate at which denudation is occurring has implications for offsite water quality. However, the extent to which soil is redistributed within the landscape can be difficult to determine. This challenge can be overcome using fallout caesium-137 (137Cs). This paper describes the rates of soil loss and remobilisation in two sub-catchments within the Sydney Basin region, namely Kembla and Kentish Creeks, which drain to the Cordeaux reservoir. The total inventories of 137Cs in catchment soils were determined, a 137Cs-regression equation and a theoretical diffusion and migration model were used to established relationships between 137Cs inventories and the rates of soil loss. These relationships revealed relatively low occurrence of soil loss in Kentish Creek, but two slopes in the Kembla Creek sub-catchment had losses that appear to be moderate. However, there was no clear evidence to suggest whether slopes in upper and lower reaches of catchments had specific patterns of soil remobilisation. Qualitative categorisation of the slope elements using a 137Cs-sediment hillslope model can be a useful sentinel for land users and decision makers even if absolute rates of soil loss or gain are not certain. The findings suggest that sediments mobilised in the study sub-catchments are not likely to impact significantly on the water quality in the Cordeaux reservoir. 相似文献
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东北黑土区主要黑土土种的容许土壤流失量 总被引:4,自引:0,他引:4
容许土壤流失量(T 值) 是进行水土流失治理的定量标准,目前以专家经验确定为主,缺乏定量研究。本文以我国重要的粮食生产基地东北黑土区为研究区,实地调查区内21 个黑土土种典型剖面的厚度,采集分层土壤样品测定理化性质后,利用修订的生产力指数模型计算了21 个土种的T值,并分析其影响因素。结果显示:21 个土种的T值变化于68~358 t/km2×a,平均141 t/km2×a。按亚类T 值为白浆化黑土(漂白滞水湿润均腐土) 106 t/km2×a,黑土(简育湿润均腐土)129 t/km2×a,草甸黑土(斑纹简育湿润均腐土) 为184 t/km2×a。土壤厚度和土壤侵蚀脆弱性指数是影响T值的主要因素,它们与T值的相关系数分别为0.750 和0.605。草甸黑土厚度明显高于其它两个土壤亚类,脆弱性指数与黑土接近,其T值较黑土T值大42.6%。白浆化黑土厚度较黑土厚度大22.1%,但T值却比黑土T值小21.7%,因为白浆化黑土有明显的障碍层存在。因此确定不同土种或亚类的T值,更能反映土壤剖面特性,对于指导水土流失治理更具实际意义。 相似文献
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A large proportion of the rural labor force in China will continue to transfer to non-agricultural sectors in the near future, which will inevitably lead to the transformation of the agricultural production mode and the structure of the farmers’ livelihood. The Chinese government is making great efforts to govern agricultural nonpoint source pollution (ANSP), and farmers' environmental behavior is a key factor that must be considered in the formulation of agricultural environmental policies. Based on a set of micro survey data on farmers in the study area and econometric methods, this study investigates the impact of agricultural labor transfer on ANSP by considering the substitution effect of agricultural factors and the effect of agricultural economies of scale. The results show that the increase of the agricultural labor force will not be conducive to reducing ANSP, while the income increase brought by agricultural labor transfer will improve the input structure of agricultural factors and have a positive impact on ANSP reduction. Government departments should provide subsidies or incentive measures to help agricultural social service organizations to expand their coverage and increase the frequency of socialized agricultural services, in order to guide farmers in the use of environment-friendly agricultural technology to reduce the ANSP caused by agricultural factors at the source. Furthermore, it is necessary to facilitate the development of small-sized agricultural machinery suitable for small-area land cultivation. 相似文献
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基于遥感和137Cs方法的半干旱草原区土壤侵蚀量估算 总被引:2,自引:0,他引:2
结合遥感地学分析方法和地球化学放射性同位素——137Cs示踪技术对青藏高原东北部共和盆地塔拉滩草原地区的土壤风蚀量进行估算。利用遥感数据获取研究区土壤侵蚀强度相对等级图斑,在不同等级侵蚀空间信息中选取137Cs样品采集点,并测定土壤样品中的137Cs含量,以此确定不同等级侵蚀类型的土壤侵蚀量。结果表明,在本研究区发生的风力侵蚀强度不大,主要属于微度侵蚀和轻度侵蚀类型,分别占研究区总面积的47.12%和35.58%,二者占研究区总面积的82.70%,侵蚀模数介于220.28~580.13 t·km-2·a-1之间;只有极小区域发生了强烈以上侵蚀,面积为22.14 km2。在本区还发生强烈的堆积过程,出现大面积的风沙堆积区域,面积约322.67 km2,占研究区总面积的11.78%。本区年均土壤总侵蚀量约为87~115万t,总堆积量约为55~78万t,平均每年由塔拉滩向龙羊峡水库输入的土壤量约为32~37万t。此方法可以对干旱环境中土壤风力侵蚀进行快速的较为客观的估算,具有一定的应用前景。 相似文献
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Spatial distribution and morphologic characteristics of gullies in the Black Soil Region of Northeast China: Hebei watershed 总被引:4,自引:0,他引:4
Gully erosion in the Black Soil Region of China has posed a threat to food security. This study aimed to determine the spatial distribution and morphologic characteristics of gullies in the region and their topographic thresholds. A 28 km2 watershed was surveyed and 117 gullies measured. The results showed that: (1) Gullies were distributed equally on both hillslope and valley floor positions, with a total gully density of .66 km/km2. (2) The mean depth, width, and cross-sectional area of gullies were .74 m, 2.39 m, and 2.43 m2, respectively. These characteristics varied among gullies according to their topographic positions and slope gradients. Individual gully volume (V) was well predicted from gully length (L) by V = 2.08L0.96 (r2 = .66). Total gully volume (V) of each sub-watershed was predicted from mean slope gradient (S) and drainage area (A) as V = 275800S ? 8600A (r2 = .73). (3) Gully erosion was more serious in steeper sub-watersheds and steeper hillslope positions. Gullies were wider in regions with relatively larger drainage areas, except for those developed in the main valley. The topographic threshold for gully initiation was S = .10A?0.34, which indicated gully erosion was dominated by surface runoff. (4) Human activities, such as road construction, played a significant role in gully erosion. 相似文献
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东北黑土区保护性耕作的发展现状与成效研究 总被引:1,自引:0,他引:1
东北黑土区承担着国家粮食安全“稳压器”的重要责任。然而,由于长期超负荷开发利用导致黑土日益退化,黑土资源的永续利用受到严重制约。理论与实践证明,保护性耕作是保护黑土地、推动黑土耕地质量和耕作效益绿色增长的发展模式。综述了保护性耕作的基本内涵及其在东北黑土区的发展现状与技术概况,从保护性耕作在土壤保持、保墒效益、结构改善、固碳培肥和土壤生物多样性增加、节本增效等方面系统评估了东北黑土区实施保护性耕作后的生态与经济效益,提出黑土区实施保护性耕作存在的问题与未来发展方向,以促进黑土地保护与利用协调发展、推动保护性耕作高质量跨越式发展。 相似文献