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Soil erosion, transport and deposition by water drastically affect the distribution of soil organic carbon (SOC) within a landscape. Moreover, soil redistribution may have a large impact on the exchange of carbon (C) between the pedosphere and the atmosphere. One of the large information gaps within this research domain, concerns the fate of SOC after erosion by water. According to different (mainly laboratory) studies, soil redistribution leads to aggregate breakdown, thereby exposing the contained SOC to mineralization. Our study aims to quantify the extent to which such increased mineralization occurs in a real field situation. Carbon dioxide (CO2)‐efflux was measured in the field after an important erosion event for a continuous period of 112 days. The specific situation on the field ensured that almost none of eroded SOC was exported from the field. Measurements of CO2‐efflux were done in areas with sediment deposition, as well as in comparable areas without sedimentation. Comparison of these measurements allowed the net effect of soil deposition on CO2‐efflux to be assessed. Field data were complemented by measurements on incubated, undisturbed soil core samples, in order to disentangle the contribution of environmental factors (moisture, temperature) from any erosional effect on CO2‐efflux. Results of these measurements on the field showed that CO2‐efflux was regulated by a complex interplay of different factors (mostly soil porosity, soil moisture and soil temperature). In combination with the incubation measurements, it could be concluded that the processes of erosion and transport indeed led to an increased mineralization of SOC, as a result of aggregate breakdown and exposure of previously encapsulated SOC. This effect was, however, much smaller than observed in previous laboratory studies. Moreover, it was only important in the first weeks, immediately after the erosion event. The calculated net erosional effect on CO2‐efflux represented a mere 1·6% of total SOC, originally present in the soil. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Urban soil, forming along with the development of city, has unique properties of soil organic carbon. On the basis of field investigation and laboratory analysis, soil organic carbon (SOC) of Kaifeng city was studied, and the results showed that the characteristics of SOC were different not only among function districts in urban area, but also between urban area and suburbs. The order of SOC in topsoil was industrial district > recreational district > traffic district > cultural/educational district > residential/administrative district. The density of soil organic carbon (SOCD) in both topsoil and profile followed the orders of recreational district > industrial district > traffic district>cultural/educational district > residential/adminis- trative district, and cultural/educational district > traffic district>industrial district>recreational district > administrative/residential district, respectively. SOCD in both topsoil and profile decreased along the transection line from urban area to suburbs and urban area had 2.53-fold more SOCD in topsoil and 1.56-fold more SOCD in profile than suburbs, respectively. SOC decreased with the depth and was mainly distributed within the scope of 0–30 cm. The variances of SOC in urban area were more complicated than that in suburbs. 相似文献
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Ditte Strebel Bo Elberling Elke Morgner Heike E. Knicker & Elisabeth J. Cooper 《Polar research》2010,29(1):46-57
The influence of goose grazing intensity and open-topped chambers (OTCs) on near-surface quantities and qualities of soil organic carbon (SOC) was evaluated in wet and mesic ecosystems in Svalbard. This study followed up a field experiment carried out in 2003–05 (part of the project Fragility of Arctic Goose Habitat: Impacts of Land Use, Conservation and Elevated Temperatures). New measurements of soil CO2 effluxes, temperatures and water contents were regularly made from July to November 2007. SOC stocks were quantified, and the reactivity and composition measured by basal soil respiration (BSR) and solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy. Results reveal variations in soil carbon cycling, with significant seasonal trends controlled by temperature, water content and snow. Experimental warming (OTCs) increased near-surface temperatures in the growing season, resulting in significantly higher CO2 effluxes. Different grazing intensities had no significant effects on observed soil respiration, but BSR rates at the mesic site (13–23 µg CO2 g soil-C−1 h−1 ) were highest with moderate grazing and lowest in the absence of grazing. A limited effect of grazing on microbial respiration is consistent with a lack of significant differences in SOC quantity and quality. NMR data show that the composition of A-horizon SOC is dominated by O-N-alkyl C and alkyl C groups, and less by carboxyl C and aromatic C groups: but again no marked variation in response to grazing was evident. It can be concluded that two years after a goose grazing experiment, SOC cycling was less than the natural variation within contrasting vegetation types. 相似文献
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干旱区土壤有机碳含量与土壤理化性质相关分析 总被引:7,自引:1,他引:6
干旱区土壤碳库是全球碳库的重要组成部分,在全球碳循环中起着重要作用.本文根据干旱区土壤相关数据资料,分析土壤有机碳与土壤理化性质相关性,为干旱区碳循环提供理论依据.结果表明:土壤有机碳含量与土壤营养成分和交换性阳离子含量呈显著正相关,与土壤pH值和容重呈显著负相关.此外,干旱区土壤也存在相当比例的无机碳,土壤有机碳和无机碳含量呈显著负相关,二者间关系还需要结合母质、生物气候条件、人类活动影响进行进一步说明. 相似文献
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Lin Liu Zhongwu Li Haibing Xiao Bing Wang Xiaodong Nie Chun Liu Lingshan Ni Danyang Wang 《地球表面变化过程与地形》2019,44(10):1895-1909
Organic carbon (OC) is easily enriched in sediment particles of different sizes due to aggregate breakdown and selective transport for sheet erosion. However, the transport of aggregate-associated OC has not been thoroughly investigated. To address this issue, 27 simulated rainfall experiments were conducted in a 1 m × 0.35 m box on slope gradients of 15°, 10°, and 15°and under three rainfall intensities of 45 mm h−1, 90 mm h−1 and 120 mm h−1. The results showed that OC was obviously enriched in sediment particles of different sizes under sheet erosion. The soil organic carbon (SOC) concentrations of each aggregate size class in sediments were different from those in the original soil, especially when the rainfall intensity or slope was sufficiently low, such as 45 mm h–1 or 5°, respectively. Under a slope of 5°, the SOC enrichment ratios (ERocs) of small macroaggregates and microaggregates were high but decreased over time. As rainfall intensity increased, OC became enriched in increasingly fine sediment particles. Under a rainfall intensity of 45 mm h–1, the ERocs of the different aggregate size classes were always high throughout the entire erosion process. Under a rainfall intensity of > 45 mm h–1 and slope of > 5°, the ERocs of the different aggregate size classes were close to 1.0, especially those of clay and silt. Therefore, the high ERocs in sediments resulted from the first transport of effective clay. Among total SOC loss, the proportion of OC loss caused by the transport of microaggregates and silt plus clay-sized particles was greater than 50%. We also found that low stream power and low water depth were two requirements for the high ERocs in aggregates. Stream power was closely related to sediment particle distribution. Flow velocity was significantly and positively related to the percentage of OC-enriched macroaggregates in the sediments (P > 0.01). Our study will provide important information for understanding the fate of SOC and building physical-based SOC transport models. © 2019 John Wiley & Sons, Ltd. 相似文献
38.
华东地区农田土壤有机碳时空格局动态模拟研究 总被引:9,自引:0,他引:9
基于已建成的农田土壤有机碳模型与GIS空间数据库的耦合,对华东6省(市)1980—2000年农田土壤有机碳时空变化进行模拟。结果表明:20年来该区土壤有机碳总体呈增加趋势,其中增加、持平和减少的面积分别占89.3%9、.5%和1.2%。1980—1985年土壤有机碳增加迅速,1985—1991年增加速率最快,其后趋缓。20年来农田土壤有机碳储量累计增加166 Tg,范围为140~193 Tg。其中安徽和江苏SOC储量增加量约占总增量的59.3%,上海、福建、江西和浙江占40.7%。 相似文献
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《地理研究》2012,31(1)
纳帕海湿地区4类土壤退化程度由高到低依次为:弃耕地-中生草甸土(AFMMS)、中生草甸土(MMS)、湿草甸土(wMS)和沼泽土(MS),对4类土壤0~10cm(上层)、10~20cm(中层)、20~30cm(下层)进行采样,分析土壤有机碳(SOC)、活性有机碳(LOC)和溶解有机碳(DOC)含量。结果表明:4类土壤间,除AFMMS中下层L0c含量略高于MMS对应层LOC含量外,其它各层SOC、LOC、DOC含量都为AFMMS〈MMS〈wMS〈MS;剖面垂向上,MS的s0C和LOC含量由上向下先增后减,其它土壤SOC、LOC、DOC含量以及MS的DOC含量均由上向下减少;LOC/SOC(%)变化于8.6~16.8%,而DOC/SOC(%)、DOC/LOC(%)更低;除AFMMS外,其它3类土壤SOC和LOC含量呈显著正相关,且LOC和LOC/SOC(%)分异与土壤类型分异有明显的对应关系,而DOC含量与s0C和LOC含量的相关性无明显规律。本研究表明,微地貌制约下的水文情势一植被生态分异对湿地SOc及活性组分的分异有显著影响,而强人为干扰会带来湿地土壤有机碳活性组分的明显损失,缺乏水文生态调控的撂荒式恢复难以有效恢复退化高寒湿地土壤有机碳库;LOC是表征湿地土壤有机碳库及其活性组分变化更为敏感和合适的指标。 相似文献
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Content and densities of soil organic carbon in urban soil in different function districts of Kaifeng 总被引:2,自引:0,他引:2
Urban soil, forming along with the development of city, has unique properties of soil organic carbon. On the basis of field
investigation and laboratory analysis, soil organic carbon (SOC) of Kaifeng city was studied, and the results showed that
the characteristics of SOC were different not only among function districts in urban area, but also between urban area and
suburbs. The order of SOC in topsoil was industrial district > recreational district > traffic district > cultural/educational
district > residential/administrative district. The density of soil organic carbon (SOCD) in both topsoil and profile followed
the orders of recreational district > industrial district > traffic district>cultural/educational district > residential/administrative
district, and cultural/educational district s>traffic district>industrial district>recreational district > administrative/residential
district, respectively. SOCD in both topsoil and profile decreased along the transection line from urban area to suburbs and
urban area had 2.53-fold more SOCD in topsoil and 1.56-fold more SOCD in profile than suburbs, respectively. SOC decreased
with the depth and was mainly distributed within the scope of 0–30 cm. The variances of SOC in urban area were more complicated
than that in suburbs. 相似文献