博斯腾湖沉积物无机碳空间分异规律及其来源研究

Lakes play an important role in the terrestrial carbon caycle research. Recent studies indicate that the arid land may have great potential for carbon sequestration, and carbonate in lake sediment may play a bigger role than organic carbon. Understanding the relationship between inoganic and organic carbon in lake sediment is crucial benifit for lake carbon cycle. However, little is known about the dynamics of inorganic carbon in arid lakes. So one of current key questions is how to quantify the sources of inorganic carbon and explore the spatial distribution characteristic in lake sediment. In order to achieve this issure, Bosten Lake, one typical arid lake, is selected as the study area. Our objectives are to (1) investigate the spatial variability of inorganic carbon based on 30 surface cores; (2) quantify the sources of inorganic carbon using the end member mixing model; (3) analyse the drving mechanism of inorganic carbon burial in response to the interactive effects of climate change and human activities, by multi-proxies of lacustrine sediment in Bosten Lake. Toward this end, this study will provide a scientific basis for the further elucidation of the relathionship between carbon sink and source in arid lake sediments.

如何定量区分湖泊沉积物无机碳的来源，探明沉积物无机碳空间分布差异规律，深化对湖泊系统内部有机碳、无机碳累积转化的认识已成为湖泊碳循环研究的难点和热点问题。本项目以干旱区典型湖泊博斯腾湖为研究对象，使用重力采样器（Kajak gravity corer）于大湖区湖面进行多钻孔沉积物样品采集，依据各点位无机碳含量的变化特点，探明该湖沉积物无机碳空间分布格局，同时根据质量守恒原理，采用端元混合模型定量区分内外源对沉积物无机碳的贡献，并结合同步测定的其它物理指标（含水量、干容重、磁化率、粒度组分）、地化指标（TOC、TN）及水深、水质、气象指标等，探讨无机碳沉积的影响因素，揭示气候变化和人类活动双重驱动下博斯腾湖沉积物无机碳的空间分异规律，为进一步阐明干旱区湖泊沉积物碳源/汇的关系提供科学依据。

如何定量区分湖泊沉积物无机碳的来源，探明其空间分布差异规律，深化对湖泊系统内部无机碳沉积过程的认识已成为干旱区湖泊碳循环研究的难点问题。本项目在前期对博斯腾湖水体及沉积物有机碳来源和埋藏速率研究的基础上，继续和深入开展了对干旱区典型湖泊沉积物无机碳来源及其空间分布差异研究。研究发现：博斯腾湖表层沉积物无机碳含量高于有机碳，其空间上呈现出条带状的分布特征，湖泊北部水域明显高于南部，最高值出现在西北黄水沟一带，最低值出现在西南河口区；沉积物碳酸盐主要以方解石和文石构成，湖水饱和系数法和同位素质量守恒法均证实博斯腾湖表层沉积物无机碳主要是自生来源。湖泊水文条件、蒸发、生物活动、水质及人类活动干扰等对沉积物无机碳的时空变化有重要作用。本项目为更好的理解内陆水体碳酸盐形成于分布、关键生物地球化学过程等提供了科学依据，同时端元混合模型方法在中国北方河口及近海水域碳循环研究中也得到了很好的应用。