滨海湿地是陆地和海洋的交错过渡地带，有机质的分解速率低，单位面积碳储量在各类陆地生态系统中最高。环渤海地区是我国滨海湿地分布最集中的区域，是有机质分解、转化、沉积的重要场所，也是揭示海洋中陆源有机碳“失汇”的关键地带。探讨该地区有机碳的动态变化及其控制过程，对揭示陆海交错带的碳循环有着重要的意义。木质素是陆源植物中的特有成分，结构稳定、难以降解。因此，被作为陆源有机碳的标志物广泛应用于地球化学的研究中。然而，现有的方法难以直接对木质素进行定性和定量的检测，必须通过氧化裂解，将大分子转化成苯酚结构的单体进行分析，该方法具有一定的误差和局限性。本项目拟开发质谱方法，深入研究木质素及其降解产物，解析样品的元素组成和结构特征，量化不同的木质素分子以及亚基单元，针对各个细分的端元筛选出具有地球化学指征意义的木质素个体，开发定量分析的方法，评估不同端元的有机质对于环渤海地区碳循环的贡献。

Coastal wetland is the transition zone between the land and ocean ecosystems. The degradation of organic matters is very slow in wetland, which makes its carbon storage per square meter highest among various terrestrial ecosystems. The Bohai Rim region has the most coastal wetlands in China, which is a crucial region for the decomposition, transformation and deposition of natural organic matters, and it is also a key area to study "why the terrestrial organic carbon is lost in the ocean". To explore dynamic changes of the organic carbons in the region together with their control process is of great importance to reveal the carbon cycle of the interlaced zone. Lignin is a unique component in terrestrial plants, whose structure is stable and resistant to degradation. Lignin is therefore widely used as a biomarker of terrestrial organic carbon in geochemical research. However, existing analytical methods are not able to characterize lignin compounds qualitatively and quantitatively. The lignin polymers must be degraded into small phenol monomers before analysis, and therefore, such a method has its own limitations and often causes errors. This project intends to develop advanced mass spectrometry methods to study lignin and its degradation products, analyze their elemental compositions and structural characteristics, and quantify different lignin molecules and subunits. To screen the geochemically important lignin individuals from different environmental samples, develop methods for quantitative analysis, and finally, to assess the contribution of organic matters from different sources to the total carbon cycle.