水分梯度下若尔盖高寒泥炭地土壤可溶性有机质光谱特征

川西高寒泥炭地是中国乃至全球最大的高寒土壤碳库之一,目前正经历着干旱化和植被退化的影响。水溶性有机质(DOM)是有机碳中活性较高的组分,对土壤碳动态平衡乃至源汇转换具有重要意义,同时也是联系陆地土壤和水生生态系统之间碳交换的主要载体,对水环境质量有重要影响。为了解干旱化对若尔盖高寒泥炭地土壤可溶性有机质含量及结构特征的影响,以四川省阿坝藏族羌族自治州若尔盖县高寒泥炭地不同水分环境下表层土壤(0-10cm)水溶性有机质(DOM)为对象,采用三维激发发射矩阵荧光光谱、平行因子分析(EEM-PARAFAC)以及荧光区域积分(FRI)等方法,对其数量和光谱学特征进行了比较研究。结果表明:(1)随着土壤干旱化程度加深,若尔盖泥炭地土壤总有机碳和水溶性有机碳含量而显著降低,降低程度分别为55.36%、28.77%;(2)川西高寒泥炭地DOM的荧光光谱特征参数表明,DOM的芳香性与腐殖化程度随着水分的增加而降低,土壤DOM稳定性降低,微生物可利用性降低;(3)平行因子分析结果显示若尔盖泥炭地土壤DOM中以小分子类腐殖质组分载荷最高,微生物活动和转化过程中蛋白物质类组分最低;(4)高原泥炭地土壤DOM中富里酸类有机质和腐殖酸类有机质占比最高,漫岗草甸土壤中腐殖酸占比高于湿地土壤,而湿地土壤富里酸组分占比高于漫岗草甸土壤。总之,若尔盖湿地干旱化将导致泥炭地土壤碳含量显著性降低,可能导致土壤有机碳将大规模排放。

Spectroscopic Characteristics of Dissolved Organic Matter(DOM) in Zoige Alpine Peatland Soils along A Soil Moisture Gradient

The alpine peatland in Western Sichuan is one of the largest roles as soil carbon pools in China and even in the world,and currently undergoes aridification and vegetation degradation.Water soluble organic matter(DOM)is a highly active component of soil organic carbon,which is of great significance to the dynamic balance of soil carbon as well as the source-sink conversion.DOM is also the main carrier of carbon exchange between terrestrial soil and aquatic ecosystem,and has an important impact on the quality of water environment.DOM extracted from the surface layer(0-10 cm)of the peatland along a soil moisture gradient in Zoige County,Aba Tibetan and Qiang Autonomous Prefecture,Sichuan Province was characterized to understand the impact of aridification on the content and structural characteristics of DOM.By use of the three-dimensional excitation emission matrix fluorescence coupled with parallel factor analysis(EEM-PARAFAC)and fluorescence regional integration(FRI)method,the quantity and spectroscopic characteristics of DOM were compared.The results showed that:with increase of the soil aridity,the total organic carbon and dissolved organic carbon content of Zoige peatland soils significantly decreased by 55.36%and 28.77%,respectively;According to the characteristic parameters of fluorescence spectra of DOM in the Western Sichuan alpine peatland,the aromaticity and humification degree of DOM decreased with the increase of water content,the stability and the microbial availability of soil DOM also decreased;The results of parallel factor analysis showed that the small molecule humus component had the highest loading in the Zoige peatland soil DOM,while the protein-like component that was related to the microbial activity and transformation had the lowest loading;the proportion of fulvic acid-like and humic acid-like components in the DOM of plateau peatland soil was the highest,the proportion of humic acid-like components in the meadow soil was higher than that in the wetland soil,while the proportion of fulvic acid-like in the wetland soil was higher than that in the meadow soil.Overall,the aridification of Zoige wetland will lead to the significant decrease of soil carbon content in peatland soils,which may result in a large-scale emission of soil organic carbon.