摘要
岩溶作用通过固定大气CO_(2)并调控陆地—河流—海洋无机碳通量,在全球碳循环中具有重要作用,但华南亚热带地区不同植被类型和土壤深度下碳酸盐岩溶蚀特征及其控制机制仍缺乏系统认识。文章采用溶蚀试片法,对粤北典型岩溶区2种植被覆盖下的不同埋放位置(地上30 cm、地表0 cm、土下20 cm、土下50cm)的碳酸盐岩溶蚀速率展开实验研究。结果表明:常绿阔叶林下碳酸盐岩平均溶蚀速率[204.4±238.7g/(m^(2)·a)]高于针叶林[27.5±20.1 g/(m^(2)·a)],阔叶林和针叶林下岩溶作用产生的碳汇强度分别为54.6±63.8g C/(m^(2)·a)和7.3±5.4 g C/(m^(2)·a)。此外,碳酸盐岩溶蚀速率随着土壤深度增加而增加,其中土下50 cm处溶蚀速率达282.4±313.2 g/(m^(2)·a),为地表0 cm[57.5±57.5 g/(m^(2)·a)]的5倍。植被类型和土壤温度是调控小区域尺度溶蚀速率的关键因子,其中土壤温度与溶蚀速率呈显著负相关(P<0.01)。随着土壤深度增加,土壤温度呈下降趋势,表明在华南地区温度上升会抑制岩石风化。
Carbonate dissolution,a key process in the global carbon cycle,sequesters large quantities of atmospheric CO_(2) and directly regulates inorganic carbon fluxes from terrestrial,river,and ocean ecosystems.Therefore,the accurate quantification of carbonate dissolution rates is essential for refining global carbon cycle models.Although carbonate dissolution rates and their influencing factors have been extensively studied in southwestern karst regions in China,such research in subtropical southern China remains limited,especially regarding the dissolution characteristics,environmental drivers,and dissolution mechanisms under different vegetation types and soil depths.This limits the accuracy of regional and global carbon sink assessments,as the unique environmental conditions in southern China may drive distinct carbonate dissolution dynamics compared with those in the southwestern parts of the country.To address this knowledge gap,we focused on key scientific questions regarding carbonate dissolution characteristics,environmental controlling factors,and dissolution mechanisms under different vegetation types and soil depths in the subtropical karst region of northern Guangdong.We used the dissolution tablet method,a reliable technique for simulating natural rock weathering,to measure the dissolution rates across four burial positions(30 cm above ground,0 cm at the ground surface,20 cm below ground,and 50 cm below ground)under two dominant vegetation cover types(evergreen broad-leaved forest and coniferous forest)in the Shimentai National Nature Reserve,a typical karst area in northern Guangdong.The following three critical results were found:(1)The vegetation type significantly affected the carbonate dissolution rate and carbon sink intensity.The average dissolution rate under the evergreen broadleaved forest(204.4±238.7 g·m^(-2)·a^(-1))was approximately 7.5 times higher than that under the coniferous forest(27.5±20.1 g·m^(-2)·a^(-1)).Correspondingly,the karst carbon sink intensity under the broad-leaved forest(54.6±63.8 g C·m^(-2)·a^(-1))was approximately 7.4 times greater than that under the coniferous forest(7.3±5.4 g C·m^(-2)·a^(-1)).(2)The dissolution rate increased significantly with increasing soil depth.The rate at 50 cm below ground(282.4±313.2g·m^(-2)·a^(-1))was 5 times higher than that at the ground surface(57.5±57.5 g·m^(-2)·a^(-1))and 2.4 times higher than that at 20 cm below ground(119.5±102.9 g·m^(-2)·a^(-1)),highlighting deep soil as being a hot spot for karst carbon sequestration in southern China.(3)The soil temperature was the core environmental factor regulating the dissolution rate at the small watershed scale,showing a significant negative correlation with this parameter(p<0.01).The soil temperature decreased with increasing soil depth,and this cooler microenvironment promoted carbonate dissolution,indicating that warming may inhibit rock weathering in the subtropical context of southern China,a pattern distinct from that of temperate regions.This study provides critical in situ data on the carbonate dissolution rate and karst carbon sink intensity in the subtropical karst region of southern China,addressing the information gap in this understudied area.By identifying vegetation type and soil temperature as the key controlling factors and elucidating the mechanism of depth-dependent carbonate dissolution,our findings contribute to the development of region-specific carbonate weathering models for subtropical karst systems.This study also supports more accurate regional carbon sink assessments and provides science-based strategies for enhancing natural carbon sequestration in karst ecosystems of southern China.
作者
唐伟华
李丰旲
骆俊燊
赵敏
张德帅
任中凯
任叶叶
杜建会
张海成
Tang Weihua;Li Fengtai;Luo Junshen;Zhao Min;Zhang Deshuai;Ren Zhongkai;Ren Yeye;Du Jianhui;Zhang Haicheng(School of Geography and Planning,Sun Yat-Sen University,Carbon-Water Research Station in Karst Regions of Northern Guangdong,Guangzhou 510275,China)
出处
《热带地理》
北大核心
2026年第2期341-357,共17页
Tropical Geography
基金
国家自然科学基金青年科学基金项目(42301020)
广东省基础与应用基础研究基金项目(2024A1515010929)。
关键词
岩溶区
碳酸盐岩风化
碳循环
地质碳汇
溶蚀试片
溶蚀速率
粤北
karst region
carbonate rock weathering
carbon cycle
geological carbon sink
dissolution tablets
dissolution rate
northern Guangdong
