若尔盖泥炭地溶解有机碳季节变化特征及其影响因素

DOC(溶解有机碳)是泥炭地碳循环中最活跃、最敏感的指标. 以若尔盖木里苔草(Carex muliensis)泥炭地为研究对象,分析了2012年该泥炭地DOC季节变化特征及其影响因素,旨在揭示泥炭地碳循环特征及其对全球变化的潜在响应. 结果表明:若尔盖木里苔草泥炭地孔隙水中ρ(DOC)季节变化显著(P<0.001, n=12),总体呈先升后降趋势,8月和5月分别出现最高值(42.77mg/L)和最低值(26.27mg/L). DOC复合物组成结构季节变化明显,主要表现在:在整个生长季节,DOC复合物芳香组分〔A₂₅₄/ρ(DOC),其中A₂₅₄为波长254nm处的吸光度,余同〕及有色组分相对含量〔A₄₀₀/ρ(DOC)〕逐渐增加,变化范围分别为0.02~0.05和0.002~0.007；5—7月DOC复合物腐殖化程度(E4/E6,即A₄₅₀/A₆₅₀)迅速降低,8—10月又逐渐增强. 此外,土壤层温度、地表温度及相对湿度是泥炭地孔隙水ρ(DOC)季节变化的主要影响因素,三者的R2分别为0.522、0.486和0.369,降水量则对有色组分含量和腐殖化程度的季节动态有很大贡献(R分别为0.748、-0.604),同时腐殖化程度还受到土壤层和地表温度的影响(R分别为0.744、0.722). 该研究结果有利于从DOC复合物的组成结构方面进一步了解DOC季节特征及其变化的潜在机制. 

Seasonal Dynamic Characteristics of Dissolved Organic Carbon in Zoige Peatland and Its Impact Factors

Zoige peatland, located in the northeast of Tibetan plateau, is the largest reservoir of soil organic carbon of alpine wetland in China and is sensitive to the climate change. Dissolved organic carbon (DOC) is the most active and sensitive component of carbon cycling in the peatland. Little is known about the impact of DOC on the climate change. This study focused on the seasonal dynamic characteristics of DOC and the main influenced factors in 2012in the peatland of the species, Carex muliensis, aiming to reveal the characteristics of carbon cycle in the peatland and its potential response to the climate change. Observations showed that there was a significant seasonal trend in DOC concentration of pore waters in the peatland (P<0.001, n=12). During the growing season, the DOC concentration fluctuated with seasonal changes with its maximum value (42.77mg/L) in August and the minimum value (26.27mg/L) in May, respectively. Meanwhile, there were significant seasonal changes for the components of DOC compound in the pore waters. From May to October, the relative amount of aromatic (i.e., A₂₅₄/ρ(DOC)) and coloured components (i.e., A₄₀₀/ρ(DOC)) of DOC compound increased steadily; while the humification degree (i.e., E4/E6) reduced quickly from May to July and then gradually elevated until October. Besides, correlated analysis indicated the temperature of the peat layer and surface and humidity were the major influencing factors of seasonal dynamic of DOC concentration (R2=0.522; R2=0.486; R2=0.369), whereas precipitation was dominated in the seasonal variations of coloured components and humification degree (R=0.748; R=-0.604). Moreover, its humification degree was also influenced by temperature of peat layer and surface (R=0.744; R=0.722). The results provided an insight into seasonal dynamics of DOC compounds and its potential mechanism in the view of its composition and structure.