| 中国南方表层岩溶系统的碳循环及其生态效应 |
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| 引用本文： | 蒋忠诚.中国南方表层岩溶系统的碳循环及其生态效应[J].第四纪研究,2000,20(4):325-334. |
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| 作者姓名： | 蒋忠诚 |
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| 作者单位： | 南京农业大学农业资源与生态环境研究所,南京 |
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| 基金项目： | 国家自然科学基金!（批准号：49272141和49972087） |
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| 摘 要： | 表层岩溶系统因碳酸盐岩－水－CO2(气)三相的化学动态不平衡过程而产生特殊的碳循环环节，参加循环的碳包括碳酸盐岩中的碳、大气和土壤空气CO2部分。中国南方表层岩溶系统的碳循环非常活跃，并敏感地响应岩溶动力因素的变化，从而促进了地球化学过程和生物化学过程的结合，成为大气CO2汇的重要项。中国南方表层岩溶系统的碳循环通过驱动环境的元素迁移，促进土壤有机质的积累，并影响植物所需要的矿物质营养元素的全量和有效态，进而影响岩溶区的植物物种、特有性和作物的发育。
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| 关 键 词： | 表层岩溶系统 碳循环 生态 |
| 收稿时间： | 2000-04-17 |
| 修稿时间： | 2000-04-17 |
CARBON CYCLE AND ECOLOGICAL EFFECTS IN EPI-KARST SYSTEMS IN SOUTHERN CHINA |
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| Pan Genxing Cao Jianhua Zhou Yunchao.CARBON CYCLE AND ECOLOGICAL EFFECTS IN EPI-KARST SYSTEMS IN SOUTHERN CHINA[J].Quaternary Sciences,2000,20(4):325-334. |
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| Authors: | Pan Genxing Cao Jianhua Zhou Yunchao |
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| Institution: | Pan Genxing
,Cao Jianhua
;(Institute of Resources, Ecosystem and Environment for Agriculture,Nanjing Agricultural Uniwrsity, Nanjing 210095);Cao Jianhua
;(Institute of Karst Geology, Chinese Academy of Geological Sciences; Karst Dynamics Laboratory, Ministry of Land and Resources, Guilin 541004);Zhou Yunchao
;(Institute of Resources, Ecosystem and Environment for Agriculture,Nanjing Agricultural Uniwrsity, Nanjing 210095) |
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| Abstract: | With the processes of dynamic eqinlibrium between carbonate rock, warer and CO2 （gas）, the carbon cycle occurs in epi-karst systems. The carbon in the cycle includes the solid carbon from carbonate rocks and the gas CO2 from the atmosphere and soil air. The processes and quantity of carbon cycle in karst systems are mainly controlled by three factors, the concentration of the atmospheric and soil air CO2, hydrodynamics and the composihon of carbonate rocks. The 14C results of the epi-karst water show that CO2 in the epi-karst dynamic system mainly comes from soil air CO2 created by the organic carbon. So the carbon cycle brings about a combination between the geochemical cycle of carbon and the biochemical cycle. The discharge and the runoff rate of karst water have a great influence upon the flux of carbon cycle. Because Mg can promote dissolution of carbonate rocks, and the dissolution of dolomite is usually quicker than that of limestone, the carbon modulus absorbed in karst warer in dolomite areas generally is larger than that in limestone areas in southern China. Due to the humid and warm monsoon climate, the carbon cycle is very active in karst areas in southern China. The chemical dynamic processes between carbonate rock, water and CO2（gas） can reach equilibrium in an hour or so after raining. For an epikarst spring system, the spring starts to outflow about 4 hours later after heavy raining, but the dissolved HCO3 concentyation in the spring water is at least 4 times as much as that in the surface warer on bare rocks. The carbon modulus absorbed in karst water changes sensitively with the karst dynamic factors, such as soil organic carbon, hydrodynarnic conditions and the atmospheric temperature. In the summer of 1999, the mean values of carbon modulus at Shuicheng, Maolan, Guilin and Nongla monitoring stations are 39.00, 50.76, 53.04 and 81.72 mg/L respectively, which show that the CO2 sink in humid and warm areas is higher than that in dry and cold areas, that in the forest areas is higher than that in bare rock areas, and that in dolomite areas is higher than that in limestone areas. Four calculation methods show that the calculation result of the CO2 sink in the karst processes in southern China is similar, with a mean value of about 10 million t/a. Driving elemental migration is one of the important functions of the carbon cycle in the epi-karst system in southern China. As a result this process brings about not only a special karst water environment with high concentration of HCO3, Ca2+ （and Mg2+ in dolomite area） and some trace element, but also the formation of the cretaceous soils. And the carbon cycle has also a great influence upon the labile content of elements in the cretaceous soils. On the one hand, with alkaline environments, the labile content of alkaline-earth elements is low in the soils, on the other hand, with the seepage of karst water, the labile contents of some elements in the soil in karst fissures are higher than those in A/ B and B layers of soil profile. The high content of calcium created by karst processes can lead to a higher humus content in the cretaceous soil than that in red soil in non-karst areas, generally with a organic matter of more than 10% in epi-soil. Therefore, the carbon cycle in karst areas in southern China can promote ecological effect. For example, the accumulated biological quantity under the forest environments in karst areas is higher than that in non-karst areas, and the biological accumulated rate of grass in the soil in bare rock areas is also fast. Particularly, the carbon cycle and its driving function to elemental ingration have a great influence upon the peculiarity and the diversity of karst vegetation. As a result there are a lot of peculiar plant species in the karst areas in southern China. Most of the plants are calciphile, and the distribution of the plant species is closely related to geological background. However, the active carbon cycle is also an important cause for the fragile karst environment and ecology. |
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| Keywords: | soil carbon Earth surface system carbon cycling |
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