青藏高原楚玛尔河碳素赋存形态初探

Specification of Carbon in Chumaehe River in Tibetan Plateau

为了解青藏高原楚玛尔河碳素赋存形态,于2013年4月至2014年3月采集水样,分析溶解性有机碳(dissolved organic carbon,DOC)和颗粒态有机碳(particulate organic carbon,POC)的浓度、碳稳定同位素特征值和碳氮比值、以及总溶解性碳水化合物浓度和DOC的光谱参数。结果表明,2013年4月、7月、11月和2014年2月,DOC/POC比值<1,其它月份水体有机碳均以DOC为主。δ^(13)C_(DOC)的2个峰值出现在夏季和冬季,表明DOC可能来源于土壤、冰川融水和地下水。此外,DOC碳氮比值较低,表明植物凋落物可能也是DOC的重要来源。碳稳定同位素特征值随着有机碳粒径的增大而增大,表明POC是DOC的重要来源。总溶解性碳水化合物在DOC所占比例没有明显季节变化规律,可能是低温下较弱的生物以及光降解引起。此外,冬季水体较低的紫外吸光度SUVA254(specific UV absorbance)值暗示DOC生物可利用性较其它季节要高。

Chumaerhe River was sampled and analyzed for carbon dynamics between April 2013 and March 2014. The concentrations of dissolved organic carbon（DOC）,particulate organic carbon（POC）,stable carbon isotope of DOC and POC,dissolved carbohydrates（TCHO） and UV absorbance were analyzed. The results suggested that DOC was the main fraction of organic carbon except April,July,November 2013 and February 2014. Two maximum values of stable carbon isotope of DOC were observed in summer and winter,suggesting that the soil,glacial melt water,and groundwater were the source of DOC. In addition,the low value of ratio of carbon to nitrogen in DOC suggested that the plant litter may also contribute to the DOC. The stable carbon isotope values consistently increased with size from DOC to POC,indicating that DOC was partially derived from POC. The contribution of TCHO to DOC did not show a clear season pattern,which may be caused by the weak biodegradation and photochemical degradation limited by low temperature. In addition,the low specific UV absorbance（SUVA254）in winter implied that DOC was more biodegradable than other season.