岩溶水生光合作用碳泵效应模拟研究: 不同土地利用条件下的碳通量

Carbonate takes part in the global carbon cycle by the weathering and aquatic photosynthesis processes actively. However, whether the carbon sink associated with carbonate weathering is stable or not depends on whether the dissolved inorganic carbon (DIC) generated from the rock weathering could be utilized by the aquatic photosynthetic organisms and their utilization levels. Therefore, karst carbon sink is still in dispute and needs to be systematically studied. In this proposal, to investigate the stable aquatic carbon pump effects of karst carbon sink under different land-use conditions, the simulation laboratory on karst water-carbon cycle in Puding is chosen. Under the controlled test conditions, the hydrochemistry of karst water and dual carbon isotope compositions (δ13C-Δ14C) in the system of CO2-DIC-OC-CaCO3 under different land-use conditons and different time scales are analyzed. Combining with C/N ratios of organic matter and δ13C-Δ14C and biomarkers of photosynthetic plants and soil, DIC fertilizer effects of aquatic photosynthetic organisms under different land-use conditions will be revealed. The ratio of OC produced by aquatic photosynthetic organisms will also be calculated. The results of this project will uncover the mechanism of transformation of DIC to OC by aquatic photosynthetic organisms under different land-use conditions, and will be helpful to providing the scientific support for the potential of carbon capture by aquatic ecosystem, carbon cycle related rock-weathering and global carbon missing sink.

碳酸盐在岩石风化和水生光合作用下积极参与全球碳循环。然而，碳酸盐风化能否构成稳定碳汇取决于风化产生的溶解无机碳（DIC）能否被水生光合生物利用及其利用程度。因此，岩溶碳汇不仅存在争议，也缺乏系统深入地研究。本项目针对不同土地利用下岩溶碳汇稳定的水生碳泵效应这一科学问题，利用普定岩溶水-碳循环大型模拟试验场，在可控的试验条件下，通过对不同土地利用下不同时间尺度的岩溶水体水化学和CO2-DIC-OC-CaCO3体系的双碳同位素（δ13C-Δ14C）系统分析，同时结合有机质C/N比、水生光合植物及土壤的δ13C-Δ14C和生物标志物，揭示不同土地利用下水生光合生物的DIC施肥效应等，并计算由此形成的OC比例。研究结果将揭示不同土地利用条件下水生光合生物利用DIC形成有机碳(OC)的机制，为水生生态系统固碳潜力与调控、岩石风化碳循环和全球遗失碳汇问题的解决提供新的科学支撑。

碳酸盐在岩石风化和水生光合作用下积极参与全球碳循环。然而，碳酸盐风化能否构成稳定碳汇取决于风化产生的溶解无机碳（DIC）能否被水生光合生物利用及其利用程度。因此，岩溶碳汇不仅存在争议，也缺乏系统深入地研究。本项目针对岩溶碳汇稳定的水生碳泵效应这一科学问题，利用普定岩溶水-碳循环大型模拟试验场及荔波茂兰拉桥天然泉-池系统，通过对不同时间尺度的岩溶水体水化学和双碳同位素（δ13C-D14C）特征系统分析，揭示喀斯特地表水水生光合生物利用DIC形成有机碳(OC)的机制、条件及耦合水生碳泵效应（BCP）碳酸盐风化碳汇能力；同时也对不同土地利用下的水质和水量进行了相关研究，表明土地利用的调整在水质、水量及碳循环管理中具有重要意义；以上研究结果为水生生态系统固碳潜力与调控、岩石风化碳循环和全球遗失碳汇问题的解决提供新的科学支撑。