达古冰川不同季节雪冰中溶解性有机质光谱特征变化研究

Variation of spectral characteristics of dissolved organic matter in snow/ice of Dagu Glacier in different seasons

随着气候持续变暖,冰川消融加剧,分析冰川中溶解性有机质(DOM)的光谱特性对认识有机碳的输出及其环境指示作用具有重要意义。本文分别对春、夏、秋和冬季达古冰川表层雪冰溶解性有机碳(DOC)浓度和DOM光谱演化特征进行了分析。结果表明:达古冰川不同季节新雪DOC浓度介于0.11~0.38 mg·L^(-1),季节性差异显著;不同季节粒雪/表层冰DOC浓度介于0.70~1.08 mg·L^(-1),季节性差异不显著。夏季雪冰中DOM芳香化程度较高,雪冰中DOM的主要组成是类蛋白类物质。雪冰中DOM主要是微生物活动引起的自生来源,具有新鲜度高、腐殖化程度低的特点。春季新雪DOM的来源更为丰富,包括微生物来源和陆源性输入,其他季节新雪和粒雪/表层冰DOM主要是微生物来源;受夏季冰川表面光化学过程和微生物活动的影响,夏季表层冰中DOM的腐殖化程度较其他季节高,秋冬季新雪和粒雪/表层冰中DOM的新鲜程度更高、腐质化程度更低。上述结果有助于揭示达古冰川表层雪冰DOM的内源性及季节性差异,为进一步研究DOM的演化过程及其区域生物地球化学效应提供科学依据。

With the climate warming,glacier exhibits dramatic decline in recent decades.Analyzing spectral evolution characteristic of dissolved organic matter(DOM)in surface snow/ice of glacier plays an important role to understand the output of organic carbon and environmental indication role caused by glacier ablation.In this study,the dissolved organic carbon(DOC)concentration and spectral characteristic of DOM in snow/ice from Dagu Glacier in spring,summer,autumn and winter were analyzed.The results showed that DOC concentration of fresh snow in different seasons was at the range of 0.11~0.38 mg·L^(-1) with a higher value in winter and lower value in summer,which showed a significant seasonal difference.DOC concentration of firn/surface ice in dif⁃ferent seasons was between 0.70~1.08 mg·L^(-1),with no significant seasonal difference.The fresh snow and sur⁃face ice samples in summer showed a significantly higher degree of DOM aromatization than other seasons.DOM in Dagu Glacier snow/ice was mainly composed of protein-like substances which was mainly an autochtho⁃nous source produced by microbial activities with the characteristics of low degree of humification.DOM in fresh snow in spring had more diverse sources,including microbial sources and terrestrial inputs,while DOM in other samples were mainly derived microbial sources.Due to the influence of photochemical process on the surface of glacier during summer,DOM in surface ice in summer have a higher humification degree than that in oth⁃er seasons,and the lower humification degree of DOM in autumn and winter samples.These results revealed the endogenous sources and seasonal variations characterized DOM in the surface snow/ice of Dagu Glacier,and provide scientific basis for further research on the evolution process of DOM and its regional biogeochemical effects.