黄土高原降雨驱动下流域碳输移特征及其碳流失评估：以羊圈沟坝系流域为例

通过对黄土高原典型坝系流域雨季碳沉降与径流碳输移过程的研究,探讨降雨径流过程对流域碳流失的驱动机制,并进一步评估流域碳侵蚀通量.结果表明,羊圈沟坝系流域湿、干季碳沉降月通量为3.33 kg·hm~(-2)、2.18 kg·hm~(-2),干湿季碳沉降存在一定变化且对流域碳输出贡献较小.流域8月碳输出量为944.89 kg·km~(-2),其中DOC、DIC输出量分别占55.39%、44.61%;9月碳输出量为300.29 kg·km~(-2),DOC、DIC输出量分别占23.03%、79.97%,不同降雨强度径流的碳流失量不同,总体溶解性无机碳输出比重较大.羊圈沟小雨强降雨事件中径流溶解性碳输出量为156.98 kg·km~(-2),中等雨强降雨事件中径流碳输出284.60 kg·km~(-2);该流域雨季月均碳流失模数为1.89 kg·(km~2·mon)~(-1),经评估得出研究区域年碳流失模数为2.70kg·(km~2·a)~(-1).

Characteristics of Carbon Transportation Under Rainfall Events and Associated Carbon Loss Evaluation in Loess Plateau, China: A Case Study of Yangjuangou Dam Watershed

In this study, by monitoring carbon transportation and its rainfall-runoff process during the rainy season in Loess Plateau''s Yangjuangou dam watershed, we analyzed changes in carbon transportation driven by rainfall and further evaluated the C loss flux for the dam watershed. Results showed that the monthly C wet deposition flux for the wet and dry seasons were 3.33 kg·hm^-2and 2.18 kg·hm^-2, respectively, which were only small contributions to C transportation for the watershed. C transportation under the rainfall-runoff process in this watershed can reach 944.89 kg·km^-2 and 300.29 kg·km^-2 in August and September, respectively. Different intensities of rainfall runoff lead to different C loss processes, wherein dissolved inorganic carbon (DIC) is the main C form. Under small rainfall events, the output of dissolved total carbon (DTC) in this watershed was 156.98 kg·km^-2; and the output of moderate rainfall events was 284.60 kg·km^-2. Finally, we determined that the C loss modulus of the Yangjuangou watershed was 1.89 kg·(km²·mon)^-1 in the rainy season, thus the C loss modulus for the study area could reach 2.70 kg·(km²·a)^-1.