中国河流流域化学风化和全球碳循环  

CHEMICAL WEATHERING OF LARGE RIVER CATCHMENTS IN CHINA AND THE GLOBAL CARBON CYCLE

作　　者：吴卫华[1,2] 郑洪波[1] 杨杰东[3] 罗超[1] 周斌[1] 

机构地区：[1]南京大学地球科学与工程学院表生地球化学研究所,南京210093 [2]南京大学地理与海洋科学学院,南京210093 [3]南京大学现代分析中心,南京210093

出　　处：《第四纪研究》2011年第3期397-407,共11页Quaternary Sciences

基　　金：中国地质调查局项目(批准号:水[2010]矿评03-07-08);国家863项目(批准号:2009AA06Z112);国家自然科学基金项目(批准号:40830107;40873001和41003001)资助

摘　　要：通过研究中国境内九大水系中大河流域的河水、大气降水、沉积物和岩体中的化学成分并结合水文信息,对流域中的化学风化作用及其消耗大气CO_2的能力与机制进行了粗略的调查,探讨了不同气候、岩性、地形、植被等条件下化学风化的变化趋势,分析了控制风化反应的因素,为在我国境内进行CO_2捕获与封存的场地、矿物类型选择提供了参考和依据。研究结果表明,我国境内河流流域硅酸盐和碳酸盐风化所消耗的大气CO_2分别为421×10~9～627×10~9mol/a和1323×10~9～2025×10~9mol/a,占全球河流消耗总量的4.8%～7.1%和11.1%～16.1%,显示我国作为岩溶大量分布的国家,碳酸盐风化作为一个短时间尺度上的碳汇对全球碳循环的影响更为突出。长江、黄河和珠江3条河流流域硅酸盐风化所消耗的大气CO_2量占全国河流的约2/3,而碳酸盐风化消耗的大气CO_2量占全国河流的近90%。通过对比一些典型硅酸盐岩地区河流的化学风化特征发现,热带气候条件下流经玄武岩地层的海南南渡江有着最高的硅酸盐风化速率(7.2×10~5mol/km^2·a),与赤道附近的新几内亚岛上河流相近。而在岩性相似的情况下,大气CO_2消耗速率与气温和降雨量呈正相关,与海拔成反相关关系。By analyzing the chemical compositions of river waters, rain waters, surface sediments, and rocks of large river catchments in China, combining with hydrological information, this paper uses the forward model to assess the chemical weathering rates, capacity and mechanism of the atmospheric CO2 consumption and then discusses the behaviors of chemical weathering under various conditions including climate, lithology, topography, and vegetation. The study also provides reference and basic information for selecting of sites and mineral types for CO2 capture and storage in China. The atmospheric CO2 consumptions derived from silicate and carbonate weathering in China are 421 ×10^9-627×10^9mol/a and 1323×10^9 -2025×10^9mol/a,which accounts for about 4.8% -7.1% and 11.1% -16. 1% of the total consumption from the global rivers,respectively. The results indicates that China,a country with wide distribution of karst, its contribution from carbonate weathering to the global carbon cycle is more important. The atmospheric CO2 consumptions from silicate and carbonate weathering in the Yangtze River,Yellow River,and Pearl River catchments account for about 2/3 and 90% of river catchments in China. By comparing the characteristics of chemical weathering in some small river catchments draining the typical silicate rock regions,the study finds that the Nandujiang River, which flows on basalt formations in tropical climate zone, has the highest silicate weathering rates（7.2×10^5mol/km^2a） , which is close to those rivers in New Guinea near the equator. Under similar lithology conditions, atmospheric CO2 consumption rates have positive correlation with temperature and rainfall and negative correlation with elevation.

关 键 词：河流流域 硅酸盐风化 碳酸盐风化 碳循环 

分 类 号：P343.5[天文地球—水文科学] P59[天文地球—地球物理学]