土地利用变化对典型碳酸盐岩流域风化碳汇的影响——以云南小江岩溶流域研究为例  

The impact of land use on CO_2 intake of chemical weathering in a typical karst region: a case study of Xiaojiang watershed, Yunnan Province

作　　者：刘长礼[1] 林良俊[2] 宋超[1] 王秀艳[1] 侯宏冰[1] 张云[1] 王俊坤[1] 姜建梅[1] 王晶晶[1] 裴丽欣[1] 

机构地区：[1]中国地质科学院水文地质环境地质研究所,河北石家庄050061 [2]中国地质调查局,北京100037

出　　处：《中国地质》2011年第2期479-488,共10页Geology in China

基　　金：国家重点基础研究发展计划(973)"西南喀斯特山地石漠化与适应性生态系统调控"(2006CB40320);国土资源大调查计划项目"全国主要城市环境地质调查评价"(1212010535501);水文地质环境地质研究所基本科研业务费项目(SK200906)联合资助

摘　　要：地球陆地岩石的风化过程要消耗大气或土壤中的CO2,成为大气CO2巨大的汇。以中国云南小江流域为例,研究了典型岩溶地区碳酸盐岩风化吸收CO2(碳汇)强度与土地利用变化之间的关系。选择了有代表性的12块土地及其利用变化的25个地下水监测点,分析了1982年、2003年这些监测点的600多组地下水化学监测数据。12块土地利用变化中,有4块为林地变耕地,3块未利用地变耕地,4块未利用地变林地,1块为林地变建设用地。研究结果表明:首先,土地利用变化后,地下水化学成分变化极大;第二,将风化过程中吸收大气或土壤中CO2的那部分C(用HCO3-表示)与整个风化过程中参与风化的全部C的百分比,定义为碳酸盐岩化学风化对土壤或大气CO2吸收强度(简写为CIS,%),推出了计算式子为CIS(%)=100×[1-(Ca2++Mg2+)total waters)/HCO3-total waters]。估算了4种土地利用类型从1982年到2003年22年间CIS的变化值。结果是,(1)林地的CIS比未利用地高,前者为48.84%,后者47.66%;(2)未利用地转变为耕地后,CIS平均减少了7.85%;林地转变为耕地后,CIS平均减少了8.59%;林地转变为建设用地后,CIS平均减少了1.66%,而未利用地转变为林地后,CIS平均增加了1.74%。(3)讨论了土地利用变化对CIS的影响机理,如未利用地或林地变为耕地后,(NH4)2PO4、CO(NH2)2、NH4NO3、(NH4)2SO4等氮肥的大量使用,硝化后产生的硝酸等干扰或抵消了碳酸对碳酸盐岩化学风化作用,导致了岩溶地下水中Ca2+,Mg2+离子的相对增多,HCO3-离子相对减少,促使CIS减小。The weathering process of terrestrial strata consumes atmospheric/soil CO2,forming an important sink of atmospheric CO2.This study intends to highlight the relationship between CO2 intake by carbonate weathering and land use changes in a typical karst area at Xiaojiang watershed of Yunnan Province.The authors analyzed more than 600 groups of groundwater composition data collected from 25 monitoring points in 1982 and 2003.These monitoring points were chosen from 12 typical areas of land use conversion in the watershed that consisted of four change areas from forestland to cultivated land,three from unused land to cultivated land,four from unused land to forestlands and one from forestland to construction land at Xiaojiang watershed.CO2 intake strength（CIS,%） by carbonate chemical weathering is presumedly defined as the percent of carbon fromatmo spheric/soil CO2（representation with HCO3-） in the total carbon during chemical weathering（representation with HCO3-）,and its formula is expressed as CO2 intake strength（CIS,%）=100×[1-（Ca2＋＋Mg2＋）total waters）/HCO3-total waters].The estimated results of CIS changes of four land use conversions from 1982 to 2003 show that CIS of forestland（48.84%） is higher than that of unused land（47.66%）.From 1982 to 2003 the average CIS decreases in these three land use change areas（unused land to cultivated land,forestland to cultivated land and forestland to construction land） were-7.85%,-8.59% and-1.66%,respectively.CIS increase of the change area from unused land to forestland was 1.74% on average.As for cultivated lands changed from unused land and forestland,construction land from forestland from 1982 to 2003,the ratios of Ca2＋＋Mg2＋/ HCO3-in groundwaterwere from 0.510 to 0.589,from 0.515 to 0.601,and from 0.508 to 0.525,respectively.All the ratios increased.For the conversion of unused land into forestland,the ratio declined from 0.533 to 0.524.The more the ratioincreased,the less CIS and vice versa.In addition,it is found that loss of

关 键 词：二氧化碳吸收强度 土地利用变化 化学风化 喀斯特地区 地下水 

分 类 号：P642.25[天文地球—工程地质学]