为了掌握亚热带季风气候岩溶地区流域水化学变化特征及量化流域内岩石化学风化过程对吸收大气CO2的贡献,文章选取湘西峒河流域作为研究对象,于2016年7—8月对研究区干流和7个子流域进行了水样采集与分析。结果表明:河水pH平均值为8. 31...为了掌握亚热带季风气候岩溶地区流域水化学变化特征及量化流域内岩石化学风化过程对吸收大气CO2的贡献,文章选取湘西峒河流域作为研究对象,于2016年7—8月对研究区干流和7个子流域进行了水样采集与分析。结果表明:河水pH平均值为8. 31,总体呈偏碱性。EC与TDS的变化范围较大,这主要与流域内岩性的分布有关。水中离子以Ca2+、HCO3-为主,水化学类型为HCO3—Ca型,岩性控制水化学的组成。HCO3-、Ca2+和Mg2+主要来源于碳酸盐岩的风化,其余离子来源多受人为活动影响。峒河流域干流的主要离子中,HCO3-、Ca2+和Mg2+浓度从上游至下游总体下降,反映了河流从碳酸盐岩区流向碎屑岩为主地层的过程。NO3-、K+、Na+、F-、Cl-和SO24-呈增长趋势,说明峒河受人为污染影响较大,反映出人为活动的密集程度。通过子流域的划分可知流域上游主要受灰岩以及白云岩控制,中游以灰岩控制为主,下游受砂岩、泥岩及碎屑岩控制为主。收集流域最终出口吉首观测站一个水文年的数据并运用水化学—径流法估算出峒河流域无机碳通量为60 477. 33 t CO2/a,碳汇强度为71. 15 t CO2/(km2·a)。展开更多
Nearly 18 years after the proposal of the weathering-related carbon sink concept(Berner R A.Weathering,plants and the long-term carbon cycle.Geochim Cosmochim Acta,1992,56:3225-3231),it is an appropriate timing to re-...Nearly 18 years after the proposal of the weathering-related carbon sink concept(Berner R A.Weathering,plants and the long-term carbon cycle.Geochim Cosmochim Acta,1992,56:3225-3231),it is an appropriate timing to re-evaluate its geological context with the updated dataset.Ryskov et al.(Ryskov Ya G,Demkin V A,Oleynik S A,et al.Dynamics of pedogenic carbonate for the last 5000 years and its role as a buffer reservoir for atmospheric carbon dioxide in soils of Russia.Glob Planet Change,2008,61:63-69) lately claimed that in the course of soil formation for the last 5000 years the soils of Russia fixed atmospheric carbon dioxide as pedogenic carbonate during the arid periods at a rate of 2.2 kg C/(m2 a) in chernozem,1.13 kg C/(m2 a) in dark-chestnut soil,0.86 kg C/(m2 a) in light-chestnut soil,on the basis of carbon isotopic data;however,their interpretations of the data do not appear straightforward nor persuading,and thus their claim is likely misleading.Their interpretations are also contrary to the conclusions drawn by Dart et al.(Dart R C,Barovich K M,Chittleborough D J,et al.Calcium in regolith carbonates of central and southern Australia:Its source and implications for the global carbon cycle.Palaeogeogr Palaeoclimatol Palaeoecol,2007,249:322-334) who found that Australian regolith carbonates did not capture any additional CO2;instead the carbonate was simply being remobilized from one pool to another.Here we raise comments to these explanations on the following two issues:(1) origin of pedogenic carbonate:silicate weathering vs.carbonate weathering,and(2) problems in using carbon isotopic technique to distinguish carbonates formed by silicate weathering and carbonate weathering.It is concluded that pedogenic carbonate may not be an important atmospheric CO2 sink at all,i.e.carbonate weathering-related pedogenic carbonate does not capture any additional CO2,while the CO2 capture in silicate weathering-related pedogenic carbonate is small in short-term time scales due to the slow kinetics of silicate weathering展开更多
文摘为了掌握亚热带季风气候岩溶地区流域水化学变化特征及量化流域内岩石化学风化过程对吸收大气CO2的贡献,文章选取湘西峒河流域作为研究对象,于2016年7—8月对研究区干流和7个子流域进行了水样采集与分析。结果表明:河水pH平均值为8. 31,总体呈偏碱性。EC与TDS的变化范围较大,这主要与流域内岩性的分布有关。水中离子以Ca2+、HCO3-为主,水化学类型为HCO3—Ca型,岩性控制水化学的组成。HCO3-、Ca2+和Mg2+主要来源于碳酸盐岩的风化,其余离子来源多受人为活动影响。峒河流域干流的主要离子中,HCO3-、Ca2+和Mg2+浓度从上游至下游总体下降,反映了河流从碳酸盐岩区流向碎屑岩为主地层的过程。NO3-、K+、Na+、F-、Cl-和SO24-呈增长趋势,说明峒河受人为污染影响较大,反映出人为活动的密集程度。通过子流域的划分可知流域上游主要受灰岩以及白云岩控制,中游以灰岩控制为主,下游受砂岩、泥岩及碎屑岩控制为主。收集流域最终出口吉首观测站一个水文年的数据并运用水化学—径流法估算出峒河流域无机碳通量为60 477. 33 t CO2/a,碳汇强度为71. 15 t CO2/(km2·a)。
基金supported by the Hundred Talents Program of the Chinese Academy of Sciencesthe National Natural Science Foundation of China (40872168)
文摘Nearly 18 years after the proposal of the weathering-related carbon sink concept(Berner R A.Weathering,plants and the long-term carbon cycle.Geochim Cosmochim Acta,1992,56:3225-3231),it is an appropriate timing to re-evaluate its geological context with the updated dataset.Ryskov et al.(Ryskov Ya G,Demkin V A,Oleynik S A,et al.Dynamics of pedogenic carbonate for the last 5000 years and its role as a buffer reservoir for atmospheric carbon dioxide in soils of Russia.Glob Planet Change,2008,61:63-69) lately claimed that in the course of soil formation for the last 5000 years the soils of Russia fixed atmospheric carbon dioxide as pedogenic carbonate during the arid periods at a rate of 2.2 kg C/(m2 a) in chernozem,1.13 kg C/(m2 a) in dark-chestnut soil,0.86 kg C/(m2 a) in light-chestnut soil,on the basis of carbon isotopic data;however,their interpretations of the data do not appear straightforward nor persuading,and thus their claim is likely misleading.Their interpretations are also contrary to the conclusions drawn by Dart et al.(Dart R C,Barovich K M,Chittleborough D J,et al.Calcium in regolith carbonates of central and southern Australia:Its source and implications for the global carbon cycle.Palaeogeogr Palaeoclimatol Palaeoecol,2007,249:322-334) who found that Australian regolith carbonates did not capture any additional CO2;instead the carbonate was simply being remobilized from one pool to another.Here we raise comments to these explanations on the following two issues:(1) origin of pedogenic carbonate:silicate weathering vs.carbonate weathering,and(2) problems in using carbon isotopic technique to distinguish carbonates formed by silicate weathering and carbonate weathering.It is concluded that pedogenic carbonate may not be an important atmospheric CO2 sink at all,i.e.carbonate weathering-related pedogenic carbonate does not capture any additional CO2,while the CO2 capture in silicate weathering-related pedogenic carbonate is small in short-term time scales due to the slow kinetics of silicate weathering
