Effects of erosion on the microaggregate organic carbon dynamics in a small catchment of the Loess Plateau, China
Effects of erosion on the microaggregate organic carbon dynamics in a small catchment of the Loess Plateau, China
复制标题
侵蚀对黄土高原小流域微团聚有机碳动态的影响
DOI：
10.1016/j.still.2017.08.001
复制
发表时间：
2017-12-01
影响因子：
6.5
通讯作者：
Yang, Mingyi
中科院分区：
文献类型：
--
作者：
Wang, Yixia;Fang, Nufang;Yang, Mingyi
土壤侵蚀显著影响陆地碳(C)循环的动态。侵蚀把富碳的表土带走，并将其沉积在海拔较低的地区，并在地表暴露出更深的贫碳层。然而，流域尺度土壤侵蚀引起的微团聚体土壤有机碳(SOC)的活化和沉积机制尚不清楚。本研究的主要目的是阐明不同侵蚀过程对微团聚体SOC分布和沉积的影响。以Cs-137活度和极端降雨事件为测年方法，基于微团聚体粒度分布和K均值聚类法，在碾阳沟流域淤地坝11.3m泥沙沉积剖面上识别出75个洪水对，并将其划分为3种对联类型。在每个洪水对联中，量化了三个微团聚体(250-50，50-20和20 PM)中的SOC浓度和数量。得到了以下结果。(1)~(137)Cs活度和极端降雨事件的记录可以用来描述泥沙沉积过程。(2)微团聚体含量较高的微团聚体(I型)主要与低强度降雨条件有关，而粗粒级微团聚体(III型)的SOC含量较高，主要与强降雨条件有关。(3)I型复联沉积物最可能与片状和细沟间侵蚀有关，而III型复联沉积物可能与细沟和沟谷侵蚀有关。本研究有助于在流域尺度上了解土壤侵蚀对微团聚体SOC动态的影响，并进一步阐明黄土高原淤地坝活跃的碳汇机制。
Soil erosion significantly affects the dynamics of the terrestrial carbon (C) cycle. Erosion removes C-rich topsoil and deposits it in lower-elevation areas and exposes deeper C-poor horizons at the surface. However, the mechanisms responsible for the mobilization and deposition of microaggregate soil organic carbon (SOC) due to soil erosion at the catchment scale remain unclear. The main objective of this study is to illustrate the effects of different erosion processes on the distribution and deposition of microaggregate SOC. The activity of Cs-137 and extreme rainfall events were used as dating methods Based on the microaggregate size distribution and the K means clustering approach, 75 flood couplets were identified in an 11.3-m sediment deposit profile of the check dam in the Nianyangou catchment and classified into three couplet types. In each flood couplet, the SOC concentrations and amounts in three microaggregate fractions (250-50, 50-20 and < 20 pm) were quantified. The following results were obtained. (1) 137Cs activity and a record of extreme rainfall events can be used to characterize the sediment deposition process. (2) Sediments with fine microaggregate fractions (Couplet Type I) contained abundant SOC and were mainly associated with low-intensity rainfall conditions, whereas sediments with coarse microaggregate fractions (Couplet Type III) had higher SOC concentrations and were mainly associated with high-intensity rainfall conditions. (3) Couplet Type I sediments were most likely related to sheet and interrill erosion, whereas Couplet Type III sediments were likely associated with rill and gully erosion. Our study contributes to the understanding of the effects of soil erosion on microaggregate SOC dynamics at the catchment scale and further illustrates the carbon sequestration mechanism active in check dams of the Loess Plateau.