黄土高原典型坝系流域碳氮湿沉降与水体碳氮流失特征

本研究通过对黄土高原坝系流域的碳(C)、氮(N)湿沉降过程、降雨径流过程及其基流过程的动态监测,揭示C、N湿沉降对流域水体碳氮流失的贡献,探讨C、N流失负荷在降雨-径流中的分布,进一步评估黄土高原雨季水体碳氮流失状况。结果表明,研究区域碳、氮湿沉降通量分别为173.95 kg km~(-2)mon~(-1)和43.01 kg km~(-2)mon~(-1),而通过径流的碳、氮流失量为11.52 kg km~(-2)mon~(-1)和2.19 kg km~(-2)mon~(-1)。雨季C、N湿沉降对该地区水体C、N流失的贡献率分别为65.81%和100%,其中流水侵蚀引起的C、N流失贡献率为59.20%和56.16%。黄土高原主要以流水侵蚀为主,C、N主要集中在降雨径流后期,因此截留后期径流可以有效控制养分流失。

Characteristics of carbon and nitrogen wet deposition and loss by runoff in a typical dam watershed, Loess Plateau in China

In this research, we monitored carbon (C) and nitrogen (N) wet deposition, rainfall-runoff, and base-flow processes in Loess Plateau''s dam watershed during wet season, in order to elucidate the contribution of C and N deposition to C and N loss in water body and discuss the distribution of C and N load in rainfall runoff, and then further evaluate the C and N losses during wet-season in the Loess Plateau. The results showed that the C and N wet deposition flux in this area reached 173.95 and 43.01 kg km^-2 mon^-1, respectively, whereas the C and N loss load by runoff were 11.52 and 2.19 kg km^-2 mon^-1, respectively. Therefore, the contribution rates of C and N wet deposition to the C and N loss by runoff during rainy season reached 65.81% and 100%, respectively, wherein the rainfall erosion contributed 59.20% and 56.16% of C and N loss, respectively. The rainfall erosion in Loess Plateau is mainly driving mechanism and the C and N loss mainly concentrated at the later stage of rainfall runoff, so if we take a measure to intercept the runoff at the later stage, nutrient losses will be effectively controlled. In addition, it is necessary to control nutrient loss according to local conditions to alleviate soil erosion and nutrient losses in the Loess Plateau''s dam watershed.