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为更好地理解矿区土壤退化机理,该文利用137Cs技术研究了焦作矿区具有15a沉陷历史的采煤沉陷坡土壤侵蚀特征及其对土壤养分的影响。沉陷坡137Cs含量从坡顶到下坡逐渐降低,及至坡脚急剧增大且表现出最高的值。基于137Cs本底(1 645 Bq/m2),沉陷坡坡顶至下坡表现为土壤侵蚀,而坡脚为土壤沉积。沉陷坡土壤侵蚀高达3.75 kg/(m2·a),属于中度侵蚀。沉陷坡土壤黏粒含量沿下坡方向增加,表明水蚀的分选性搬运。与对照区相比,沉陷坡侵蚀区土壤总有机碳(total organic carbon,TOC)、水溶性有机碳(water-soluble organic carbon,WSOC)、全氮、碱解氮、全磷、有效磷含量均出现了显著降低(P0.05);沉积区除WSOC显著降低(P0.05)外,其他养分含量变化不明显(P0.05)。在沉陷坡的侵蚀区,TOC与WSOC含量沿下坡方向逐渐减小,表现出与137Cs一致的分布格局;其他养分含量的坡面变化与137Cs分布不一致。相较于对照区,WSOC/TOC与碳氮比、碳磷比在沉陷坡侵蚀强烈的坡位分别出现了显著增大与降低(P0.05)。研究结果表明:1)焦作矿区自采煤沉陷坡形成以来发生了较严重的水蚀;2)侵蚀引起的土壤再分配影响沉陷坡土壤碳、氮、磷动态,其中,土壤再分配对土壤碳动态的影响最强;3)在土壤侵蚀作用下,采煤沉陷坡侵蚀强烈的坡位土壤有效态碳、氮、磷养分潜在的侵蚀风险大。采煤沉陷坡土壤侵蚀及其对土壤养分的不利影响应引起矿粮复合区土地整治的关注。 相似文献
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以黄土丘陵区典型侵蚀沟道为对象,基于沟道剖面有机碳和137Cs数据,采用碳库重分布模型估算了典型沟道侵蚀诱发的CO2通量,并通过检验模型预测效率、解析影响因子,提出了模型校正的思路。结果表明:(1)在长期侵蚀作用下,沟道侵蚀区和沉积区均表现为剧烈的侵蚀效应,侵蚀区侵蚀速率介于30.99~46.44 mm/a,沉积区侵蚀速率介于34.20~37.88 mm/a,沉积区土壤流失速率略小于侵蚀区;(2)碳库重分布模型估算显示,侵蚀区与沉积区均表现为较强烈的碳源效应,侵蚀区CO2通量介于18.41~28.44 g/(m2·a),沉积区CO2通量介于22.19~29.25 g/(m2·a);(3)侵蚀部位、土壤容重、有机碳含量、侵蚀量、沟道平均坡度、植被地上部与地下部生物量共同解释了碳库重分布模型预测效率的变异特征(R2=0.68),其中侵蚀部位、侵蚀量、有机碳含量、土壤容重、植被地下部对预测效率有强驱动效应;(4)引入被忽略的植被新输入有机碳库参数,有望校正碳库重分布模型,提升模型预测效率。该研究结果明确了碳库重分布模型在沟道侵蚀区相比沉积区有更高的CO2通量预测效率,为进一步提高模型的预测精度,可以考虑引入植被输入有机碳库作为校正参数。 相似文献
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黑土坡耕地侵蚀和沉积对物理性组分有机碳积累与损耗的影响 总被引：3，自引：1，他引：3
以侵蚀和沉积过程明显的黑土坡耕地为研究对象,通过测定不同地形部位表层和典型剖面土壤不同粒级的水稳性团聚体、颗粒态有机碳（POC）以及团聚体结合态有机碳含量,探讨土壤侵蚀和沉积对土壤有机碳（SOC）损失、迁移和累积过程的影响。研究结果表明：上坡三个侵蚀部位表层土壤大团聚体、矿质结合态有机碳（MOC）以及团聚体结合态有机碳含量随侵蚀速率增加而减小;沉积部位（尤其是坡脚）POC含量和POC/SOC较低,而MOC含量和MOC/SOC较高。始终处于沉积状态的坡脚部位,各粒级有机碳组分的深度分布均表现出土壤累积和埋藏特征,并随着粒级的减小累积现象趋于明显。上述结果反映了土壤侵蚀优先使与细颗粒和微团聚体结合的SOC迁移流失,并在低洼的沉积区累积;埋藏层中的侵蚀物质（如微团聚体、颗粒态有机质）通过深埋作用和重新团聚作用形成稳定的大团聚体,最终促进SOC的固定。 相似文献
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紫色土坡耕地土壤物理性质空间变异对土壤侵蚀的响应 总被引：11，自引：8，他引：3
为了研究不同坡度和坡长的耕地上土壤侵蚀对土壤物理性质空间变异的影响,通过地形测量、137 Cs示踪、土壤物理性质分析等方法对川中丘陵紫色土区土壤物理性质对土壤侵蚀的响应进行了研究,结果表明：在中等坡度（16.60%～25.10%）的梯坡地上,耕作侵蚀处于主导地位,是导致耕层土壤物理性黏粒含量和容重在梯坡地上总体差异不大（CV＜6.3%）,且与137Cs含量不相关的主要原因;在已退耕还林的陡梯坡地上（35.60%）,水蚀占据主导地位,导致耕层土壤物理性黏粒含量和容重均与137Cs的含量显著相关。在长坡耕地上(10.10%),具有分选搬运能力的水力侵蚀占据主导地位,致使耕层土壤物理性黏粒含量与137Cs的含量具有显著的相关关系,而容重却与137Cs含量没有显著的相关关系。川中丘陵区坡耕地上,耕作侵蚀和水蚀共同作用于土层深度,使土层深度在坡顶、上坡最浅,在坡脚最深,顺坡向下逐渐增加。因此,在川中丘陵区不同坡长的坡耕地上,占主导地位的土壤侵蚀类型导致坡耕地上土壤物理性质出现相应的变化。 相似文献
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亚热带侵蚀红壤区植被恢复过程中土壤团聚体化学计量特征 总被引：11，自引：0，他引：11
植被恢复过程中侵蚀退化地区土壤团聚体碳氮磷及其化学计量特征是反映土壤团聚体对养分固持能力以及土壤生物地球化学循环的关键环节,也是定量评价退化地植被恢复效应的重要途径。为深入了解侵蚀红壤植被恢复过程中土壤团聚体碳、氮、磷含量分配格局及其化学计量特征,以典型红壤侵蚀区福建省长汀县河田镇5个不同植被恢复年限的样地(分别为5a、10a、15a、30a、80a)以及1个未治理地(恢复0a)为对照坡地作为研究对象,测定0~20cm和20~40cm土层不同粒径团聚体有机碳、全氮、全磷含量,并分析土壤与不同粒径团聚体养分化学计量特征。结果表明:(1)植被恢复过程中,团聚体有机碳、全氮和全磷含量变化范围分别为2.06~27.71 g·kg~(-1)、0.54~2.12g·kg~(-1)和0.034~0.189g·kg~(-1),团聚体C︰N、C︰P、N︰P变化范围分别为3.06~13.05、21.4~185.6、5.62~18.20。(2)随植被恢复年限增加,各粒级团聚体有机碳、全氮和全磷含量及其C:N总体上显著增加,均表现为表土层(0~20 cm)高于底土层(20~40 cm),团聚体C︰P、N︰P随植被恢复年限增加表现为升高→降低→升高趋势,团聚体C︰P随土层加深而降低,团聚体N︰P在土层间无明显变化。(3)除恢复0 a外,团聚体有机碳,全氮、全磷和团聚体C︰N、C︰P随粒径减小总体上呈增加趋势,N︰P在各粒径间无显著差异。(4)土壤与团聚体中有机碳、全氮和全磷含量之间以及团聚体有机碳、全氮与团聚体C︰N之间均呈极显著正相关;团聚体有机碳与团聚体C︰P呈极显著正相关;团聚体全磷与团聚体N︰P呈极显著负相关。植被恢复降低土壤侵蚀,明显增加各粒径团聚体有机碳、全氮和全磷含量,提高团聚体碳氮"汇"功能,且在植被恢复过程中,团聚体中P元素成为退化生态系统恢复的限制性元素。 相似文献
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龙门山地震带坡耕地土壤侵蚀对有机碳迁移的影响 总被引：1，自引：0，他引：1
坡耕地土壤再分布对土壤有机碳(SOC,soil organic carbon)迁移的作用机制研究已成为土壤侵蚀学研究的热点,然而目前极少有研究关注地震后生态脆弱的龙门山地震带坡耕地土壤侵蚀机理及其导致的土壤有机碳再分布规律。该研究选择龙门山地震带内(都江堰市)一块陡坡耕地和一个梯田系列,采用137Cs法和野外调查,对比分析强震导致田埂垮塌和未受损情况下坡耕地土壤侵蚀空间变化特征和有机碳运移变化机理。结果表明,该区黄棕壤有效137Cs背景值为1 473 Bq/m2;坡度较小的坡式梯田内部上坡表现为侵蚀,下坡表现为沉积,同时,上部梯田的侵蚀速率高于下部梯田,但整个梯田系列净侵蚀量非常小,这表明梯田之间由于缺乏田埂的保护,水力也起着侵蚀、搬运上坡梯田土壤的作用,但是整个坡式梯田系列可以起到较好的保土作用,同时,坡式梯田内部主要以耕作侵蚀为主,是造成梯田上部坡位土壤流失严重的主要原因;陡坡耕地的地形为复合坡,由于田埂垮塌导致其土壤侵蚀速率显著高于坡式梯田系列,在整个坡面上,除了坡顶土壤侵蚀速率高之外,下坡坡度变大(曲率较大)的部位土壤侵蚀速率也非常高,同时,土壤沉积也发生在2个坡位(中下坡坡度较缓的部位和坡脚部位);在梯田系列和陡坡耕地上,SOC与土壤137Cs的空间变化规律较为一致。研究结果表明,在龙门山地震带,质量较好的石埂梯田仍然发挥着较好的土壤保持效果,同时,耕作侵蚀是该区坡耕地上一种重要的土壤侵蚀形式,在制定相应的土壤保持措施时,必须充分考虑耕作侵蚀的作用,才能有效地控制土壤侵蚀,此外,该研究结果还表明采用137Cs核素示踪技术可以比较科学地解释该区域的土壤侵蚀速率和SOC的空间变异规律。 相似文献
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植被恢复对土壤团聚体分布及有机碳、全氮含量的影响 总被引：16，自引：0，他引：16
植被是影响土壤有机碳含量和土壤结构的重要因素,植被通过凋落物影响有机碳输入的数量和质量,同时有改善土壤结构特别是水稳性团聚体的数量。探讨黄土高原侵蚀地区植被恢复后对土壤有机碳、氮及其团聚体平均重量直径的影响,研究结果显示：土壤有机碳、全氮含量与水稳性团聚体平均重量直径的变化趋势相同,平均重量直径与有机C含量之间有二次多项式关系。植被类型是影响土壤碳、氮含量的关键因素,植被恢复增加土壤养分含量,改善土壤结构和土壤环境。 相似文献
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植被恢复对亚热带侵蚀红壤团聚体养分分布的影响 总被引：1，自引：2，他引：1
为深入了解不同植被恢复年限下土壤团聚体养分分布特征,以典型红壤侵蚀区福建省长汀县河田地区恢复年限分别为0,5,10,15,30,80a的坡地土壤为研究对象,分别对0—20cm和20—40cm土层不同粒径团聚体养分含量进行测定,并分析了它们与不同团聚体的相关关系。结果表明:(1)植被恢复过程中,土壤团聚体有机碳、全氮、全磷、全钾、速效磷和速效钾含量的变化范围分别为2.06~27.71g/kg,0.54~2.12g/kg,0.034~0.171g/kg,2.20~6.89g/kg,0.31~3.30mg/kg和7.35~85.71g/kg;(2)有机碳、全氮、全磷和速效磷含量随着团聚体粒径的减小总体上表现出显著升高趋势(P0.05),全钾和速效钾含量无明显差异(P0.05);(3)随植被恢复年限增加,各粒径团聚体中有机碳、全氮、全磷、速效磷含量总体上呈显著升高趋势(P0.05),全钾含量先升高后降低,而速效钾含量表现出波动增加趋势;(4)恢复初期(0a和5a)不同土层间团聚体养分含量无明显变化(P0.05),其它恢复年限0—20cm土层团聚体有机碳、全氮、全磷、速效磷和速效钾含量显著高于20—40cm土层(P0.05);(5)团聚体对土壤养分的贡献率表现为(5mm)(2~5mm)(0.5~1mm)(1~2mm)(0.25~0.5mm)(0.25mm),2mm粒径养分贡献率达34.18%~49.93%,土壤养分含量与0.25mm粒径相关性较强(P0.01)。植被恢复在降低土壤侵蚀的同时,土壤团聚体养分含量明显增加,土壤结构得以改善,养分固持能力得到加强。 相似文献
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137Cs示踪分析东北黑土坡耕地土壤侵蚀对有机碳组分的影响 总被引：1，自引：1，他引：0
研究土壤侵蚀对有机碳不同组分流失的影响,可为科学评估土壤侵蚀在碳循环中的作用和探明农田有机碳变化机制提供理论依据。该研究以典型黑土区一凸型耕地坡面为研究对象,基于~(137)Cs示踪技术,分析了坡面土壤侵蚀特征及强度分布,定量分析了坡面有机碳组分的变化幅度及侵蚀强度与有机碳组分间的关系。结果表明:研究坡面年均侵蚀速率为3801.71t/(km~2×a),属中度侵蚀,33.33%的采样点为强烈侵蚀,极强烈及剧烈的侵蚀点占比11.11%,主要位于凸型坡中部坡度较陡处,26.67%为沉积点,主要分布在坡脚西侧。自开垦以来坡耕地土壤平均有机碳(Soil Organic Carbon,SOC)含量下降了13.58%,其中矿质有机碳(Mineral-bound Organic Carbon,MOC)和颗粒有机碳(Particulate Organic Carbon,POC)分别下降了7.52%和40.49%;POC中粗颗粒有机碳(Coarse Particulate Organic Carbon,CPOC)下降幅度最大(73.24%),细颗粒有机碳(Fine Particulate Organic Carbon,FPOC)无显著差异。坡面SOC、MOC和FPOC在沉积点均显著大于侵蚀点(P0.01),沉积点和轻度侵蚀点的SOC及MOC含量显著大于轻度以上侵蚀点(P0.01),SOC及组分MOC和FPOC均在中度侵蚀下降幅度最大,之后变化轻微。有机碳组分中MOC和FPOC含量随着土壤侵蚀强度的增大呈下降趋势,CPOC与侵蚀强度无显著相关性且沉积点及不同侵蚀强度之间均无显著差异(P0.05)。结果说明坡耕地中CPOC和MOC减少的驱动机制可能存在差异。 相似文献
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Determining how soil erosion affects enzyme activity may enhance our understanding of soil degradation on eroded agricultural landscapes. This study assessed the changes in enzyme activity with slope position and erosion type by selecting water and tillage erosion-dominated slopes and performing analyses using the 137Cs technique. The 137Cs data revealed that soil loss occurred in the upper section of the two eroded slope types, while soil accumulation occurred in the lower section. The invertase activity increased downslope and exhibited a pattern similar to the 137Cs data. The spatial patterns of urease and alkaline phosphatase activities were similar to the 137Cs inventories on the water and tillage erosion-dominated slopes, respectively. On both the eroded slope types, the invertase activity and soil organic carbon content were correlated, but no correlation was observed between the alkaline phosphatase activity and total phosphorus content. Nevertheless, the urease activity was correlated with the total nitrogen content only on the water erosion-dominated slopes. The enzyme activity-to-microbial biomass carbon ratios indicated high activities of invertase and urease but low activity of phosphatase on the water erosion-dominated slopes compared with the tillage erosion-dominated slopes. Both the invertase activity and the invertase activity-to-microbial biomass carbon ratio varied with the slope position. Changes in the urease activity-to-microbial biomass carbon ratio were significantly affected by the erosion type. These suggested that the dynamics of the invertase activity were linked to soil redistribution on the two eroded slope types, whereas the dynamics of the urease and alkaline phosphatase activities were associated with soil redistribution only on the water or tillage erosion-dominated slopes, respectively. The erosion type had an obvious effect on the activities of invertase, urease and alkaline phosphatase. Soil redistribution might influence the involvement of urease in the N cycle and alkaline phosphatase in the P cycle. Thus, enzyme activity-to-microbial biomass ratios may be used to better evaluate microbiological activity in eroded soils. 相似文献
12.
黄土丘陵区土壤有机碳含量对侵蚀坡面表层土壤含水量时空变化的影响 总被引：1，自引：0，他引：1
表层土壤含水量能敏感反映降雨、气温、侵蚀等环境要素的变化,明确表层土壤含水量时空变化特征可为农业生产及土壤环境效应评价等提供参考。以黄土丘陵区不同有机碳水平的侵蚀坡面为对象,连续监测了2016年11月至2018年3月0-5 cm土壤含水量的动态变化,结合降水资料,分析了不同土壤有机碳水平下侵蚀坡面沉积区、侵蚀区及对照区表层土壤含水量的变化特征。结果表明:(1)表层土壤含水量不同季节变化差异显著,夏季变幅最大,单日最大变幅可达14.3%,春、秋、冬季的单日最大变幅<8.0%。换言之,夏季是土壤水分变化的敏感期。(2)土壤有机碳水平、坡面部位、土壤温度对表层水分变异的影响程度因季节而异。(3)土壤侵蚀加剧了坡面表层土壤含水量变异,变异程度表现为沉积区>侵蚀区>对照(未侵蚀)区;侵蚀前后侵蚀区表层土壤含水量变化量与沉积区变化量的差值随有机碳水平升高从0.85%增加至9.81%。(4)侵蚀坡面表层土壤含水量的时空异质性随有机碳水平升高呈非线性变化趋势。 相似文献
13.
《国际水土保持研究(英文)》2023,11(1):86-96
The southeastern Tibetan Plateau, which profoundly affects East Asia by helping to maintain the stability of climate systems, biological diversity and clean water, is one of the regions most vulnerable to water erosion, wind erosion, tillage erosion, freeze–thaw erosion and overgrazing under global climate changes and intensive human activities. Spatial variations in soil erosion in terraced farmland (TL), sloping farmland (SL) and grassland (GL) were determined by the 137Cs tracing method and compared with spatial variations in soil organic carbon (SOC) and total nitrogen (total N). The 137Cs concentration in the GL was higher in the 0–0.03 m soil layer than in the other soil layers due to weak migration and diffusion under low precipitation and temperature conditions, while the 137Cs concentration in the soil layer of the SL was generally uniform in the 0–0.18 m soil layer due to tillage-induced mixing. Low 137Cs inventories appeared at the summit and toe slope positions in the SL due to soil loss by tillage erosion and water erosion, respectively, while the highest 137Cs inventories appeared at the middle slope positions due to soil accumulation under relatively flat landform conditions. In the GL, the 137Cs data showed that higher soil erosion rates appeared at the summit due to freeze–thaw erosion and steep slope gradients and at the toe slope position due to wind erosion, gully erosion, freeze–thaw erosion and overgrazing. The 137Cs inventory generally increased from upper to lower slope positions within each terrace (except the lowest terrace). The 137Cs data along the terrace toposequence showed abrupt changes in soil erosion rates between the lower part of the upper terrace and the upper part of the immediate terrace over a short distance and net deposition on the lower and toe terraces. Hence, tillage erosion played an important role in the soil loss at the summit slope positions of each terrace, while water erosion dominantly transported soil from the upper terrace to the lower terrace and resulted in net soil deposition on the flat lower terrace. The SOC inventories showed similar spatial patterns to the 137Cs inventories in the SL, TL and GL, and significant correlations were found between the SOC and 137Cs inventories in these slope landscapes. The total N inventories showed similar spatial patterns to the inventories of 137Cs and SOC, and significant correlations were also found between the total N and 137Cs inventories in the SL, TL and GL. Therefore, 137Cs can successfully be used for tracing soil, SOC and total N dynamics within slope landscapes in the southeastern Tibetan Plateau. 相似文献
14.
H. J. Fang S. L. Cheng X. P. Zhang A. Z. Liang X. M. Yang C. F. Drury 《Land Degradation \u0026amp; Development》2006,17(1):89-96
Soil organic carbon (SOC) in eroded soil can be redistributed from upper slope positions and deposited and sequestered in depressional areas. However, the SOC lost from soil erosion is normally not considered when soil carbon budgets are derived and this could result in an overestimation of SOC loss from the agricultural areas. The impact of soil redistribution on the SOC budget of a sloping landscape in the Black soil region in Northeast China was studied using the presence of the 137Cs tracer which has been deposited since 1954 and the fly‐ash tracer, which was deposited in 1903. Five landscape positions (summit, shoulder‐, back‐, foot‐ and toe‐slope) were selected and included in this study. The depths of 137Cs and fly ash and the SOC content of the deposition layers were used to calculate the change in C content of the soil in the various landscape positions over the last century. We found that the most severe soil erosion occurred in soils in the shoulder‐slope position followed by the back‐slope and the summit positions. Soil deposition occurred in the toe‐slope position followed by the foot‐slope position. A total of 683 kg C was eroded from the summit, shoulder‐ and back‐slopes (in a 1 m wide strip) over the past 100 years and 418 kg C (about 61·2 per cent) was deposited in the low‐lying areas (foot‐ and toe‐slopes). Over half (61·5 per cent) of the deposition (257 kg SOC) occurred over the past 50 years. Most of the previously reported loss of C from the upper slope positions in the Black soils was in fact sequestered in the deposition areas in the landscape. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
15.
Cesium and soil carbon in a small agricultural watershed 总被引：8，自引：1，他引：8
Scientific, political, and social interests have developed recently in the concept of using agricultural soils to sequester carbon. Studies supporting this concept indicate that soil erosion and subsequent redeposition of eroded soils in the same field may establish an ecosystem disequilibrium that promotes the buildup of carbon on agricultural landscapes. The problem is to determine the patterns of soil erosion and redeposition on the landscape and to relate these to soil carbon patterns. Radioactive 137cesium (137Cs) can be used to estimate soil erosion patterns and, more importantly, redeposition patterns at the field level. The purpose of this study was to determine the relationship between 137Cs, soil erosion, and soil carbon patterns on a small agricultural watershed. Profiles of soils from an upland area and soils in an adjacent riparian system were collected in 5 cm increments and the concentrations of 137Cs and carbon were determined. 137Cs and carbon were uniformly mixed in the upper 15–20 cm of upland soils. 137Cs (Bq g−1) and carbon (%) in the upland soils were significantly correlated (r2=0.66). Carbon content of the 0–20 cm layer was higher (1.4±0.3%) in areas of soil deposition than carbon content (1.1±0.3%) in areas of soil erosion as determined by the 137Cs technique. These data suggest that measurements of 137Cs in the soils can be useful for understanding carbon distribution patterns in surface soil. Carbon content of the upland soils ranged from 0.5 to 1.9% with an average of 1.2±0.4% in the 0–20 cm layer while carbon below this upper tilled layer (20–30 cm) ranged from 0.2 to 1.5% with an average of 0.5±0.3%. Total carbon was 2.66 and 3.20 kg m−2 in the upper 20 cm and upper 30 cm of the upland soils, respectively. Carbon content of the 0–20 cm layer in the riparian system ranged from 1.1 to 67.0% with an average 11.7±17.1%. Carbon content below 20 cm ranged from 1.8 to 79.3% with an average of 18.3±17.5%. Soil carbon in the upper 20 cm of the riparian profile was 10.1 and 15.0 kg m−2 in the upper 30 cm of the riparian profiles. This is an increase of organic carbon by a factor of 3.8 and 4.7 for the upper 20 cm and upper 30 cm of the riparian profiles, respectively, when compared to the upland soil profiles. 相似文献
16.
Distribution of soil organic carbon and phosphorus on an eroded hillslope of the rangeland in the northern Tibet Plateau, China 总被引：2，自引：0，他引：2
Some studies on the relationship between soil erosion and subsequent redeposition of eroded soils in the same field and soil quality have been conducted in croplands, yet few studies have revealed this relationship in rangelands. We selected a toposequence with a slope of 30% and a horizontal length of 342 m from the rangeland in the northern Tibet Autonomous Region, China (31°16′N, 92°09′E) to determine the relationship between soil erosion, soil organic carbon (SOC) content and available P patterns within a hillslope landscape. Soil samples for the determination of 137Cs as well as SOC, available P and particle‐size fractions were collected at 20 m intervals along a transect of this hillslope. Soil redistribution was caused primarily by wind erosion at toe‐slope positions, but primarily by water erosion at the hillslope positions above the toe‐slope. In upper‐ and mid‐slope portions (0 m to 244 m horizontal length), SOC content is closely correlated to 137Cs concentration (r = 0.74, P < 0.01, n= 15), suggesting that SOC distribution along the slope was similar to 137Cs distribution, which itself was dependent on topographic changes. However, SOC contents in toe‐slope portions are less than those above the toe‐slope (i.e. upper‐ and mid‐slope portions), and the correlation between 137Cs and SOC in the toe‐slope portion is weaker than that above the toe‐slope. A highly significant correlation (r = 0.72, P < 0.001, n= 20) between 137Cs concentration and available P was found within the whole hillslope landscape, implying the distribution pattern of available P was somewhat different from that of SOC. We suggest that the distribution of SOC within the hillslope landscape is also affected by factors such as assimilation rates due to difference in grassland productivity at different points and different biological oxidation rates of carbon related to patterns of moisture distribution. 相似文献