The conversion of CO2 into H+ and is a relatively slow reaction. Hence, its kinetics may be rate determining in carbonate rock dissolution. Carbonic anhydrase (CA), which is widespread in nature, was used to catalyze ...The conversion of CO2 into H+ and is a relatively slow reaction. Hence, its kinetics may be rate determining in carbonate rock dissolution. Carbonic anhydrase (CA), which is widespread in nature, was used to catalyze the CO2 conversion process in dissolution experiments of limestone and dolomite. It was found that the rate of dissolution increases by a factor of about 10 after the addition of CA at a high CO2 partial pressure (Pco2) for limestone and about 3 at low Pco2 for dolomite. This shows that reappraisal is necessary for the importance of chemical weathering (including carbonate rock dissolution and silicate weathering) in the atmospheric CO2 sink and the mysterious missing sink in carbon cycling. It is doubtless that previous studies of weathering underestimated weathering rates due to the ignorance of CA as an activator in weathering, thus the contribution of weathering to the atmospheric CO2 sink is also underestimated. This finding also shows the need to examine the situ distribution and activity of CA in different waters and to investigate the role of CA in weathering.展开更多
Fertilization and aglime(agricultural lime) application, as important agricultural activities in acid soil, exert an influence on the fluxes of carbon both between and within ecosystems. Animal manure added to soil ca...Fertilization and aglime(agricultural lime) application, as important agricultural activities in acid soil, exert an influence on the fluxes of carbon both between and within ecosystems. Animal manure added to soil can elevate the soil CO_2 and release organic acid due to microbial decomposition of the high organic matter content of animal manure. Additionally, the elevated CO_2 can accelerate carbonate weathering in alkaline soil, such as lime soil. However, in acidic soil, it is unclear whether the chemical weathering of additive aglime can be quickened by the elevated CO_2 due to animal manure addition. Thus, to ascertain the impact of animal manure addition on aglime weathering in acidic soil and to understand the weathering agent of aglime or underlying carbonate in the acidic soil profile, we established two contrasting profiles(control profile and manurial profile) in a cabbage-corn or capsicum-corn rotation in a field experiment site located in the Hua Xi district of Guiyang, China, and buried carbonate rock tablets at different depths of soil profiles to calculate the dissolution rate of carbonate rock by monitoring the weights of the tablets. The results indicated that soil CO_2 increased due to animal manure addition, but the rate of dissolution of the carbonate rock tablets was reduced, which was attributed to the increase in the p H in acidic soil after animal manure addition because the relationship between the dissolution rate of carbonate rock and soil p H indicated that the weathering rate of carbonate rock was controlled by pH and not by CO_2 in acidic soil. Thus, the contribution of H+ ions(mainly exchangeable acid) in acid soil as a weathering agent to the weathering of underlying carbonate(and/or aglime) may lead to the overestimation of the CO_2 consumption through chemical weathering at the regional/global scale using hydro-chemical methods.展开更多
Over the past three decades,the drawdown of atmospheric CO_(2) in vegetation and soil has fueled net ecosystem production(NEP).Here,a global land-surface model(CABLE)is used to estimate the trend in NEP and its respon...Over the past three decades,the drawdown of atmospheric CO_(2) in vegetation and soil has fueled net ecosystem production(NEP).Here,a global land-surface model(CABLE)is used to estimate the trend in NEP and its response to atmospheric CO_(2),climate change,biological nitrogen(N)fixation,and N deposition under future conditions from 2031 to 2100 in the Belt and Road region.The trend of NEP simulated by CABLE decreases from 0.015 Pg carbon(C)yr^(-2) under present conditions(1936–2005)to−0.023 Pg C yr^(-2) under future conditions.In contrast,the trend in NEP of the CMIP6 ensemble changes from 0.014 Pg C yr^(-2) under present conditions to−0.009 Pg C yr^(-2) under future conditions.This suggests that the trend in the C sink for the Belt and Road region will likely decline in the future.The significant difference in the NEP trend between present and future conditions is mainly caused by the difference in the impact of climate change on NEP.Considering the responses of soil respiration(RH)or net primary production(NPP)to surface air temperature,the trend in surface air temperature changes from 0.01℃ yr^(-1) under present conditions to 0.05℃ yr^(-1) under future conditions.CABLE simulates a greater response of RH to surface temperature than that of NPP under future conditions,which causes a decreasing trend in NEP.In addition,the greater decreasing trend in NEP under future conditions indicates that the C-climate-N interaction at the regional scale should be considered.It is important to estimate the direction and magnitude of C sinks under the C neutrality target.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
农业生态系统碳平衡对评估陆地生态系统的源和汇具有重要意义,针对烤烟生长及管理的特殊性,研究烟田生态系统碳收支,为提升烟田管理及农业碳汇估算提供依据。本研究以定位试验为平台,以单施化肥处理为研究对象,于2015-2017年观测了烤烟...农业生态系统碳平衡对评估陆地生态系统的源和汇具有重要意义,针对烤烟生长及管理的特殊性,研究烟田生态系统碳收支,为提升烟田管理及农业碳汇估算提供依据。本研究以定位试验为平台,以单施化肥处理为研究对象,于2015-2017年观测了烤烟生长季的碳收支。研究结果表明,烤烟生物量平均为(5832.10±537.32)kg hm?2;烟株碳含量平均为(42.14±0.05)%,累积固碳量为(2459.25±233.78)kg hm?2。烤烟根系碳占烟株碳比例较高,平均为24.94%。烤烟生长季湿沉降碳达到了115.32 kg hm?2,干沉降碳量为6.54 kg hm?2,两者占根系碳的20.01%。烟生长季碳输出总量为2464.98kghm?2,其中CO2排放碳占碳支出的98.99%,径流损失碳占支出的0.76%,淋溶损失碳占支出的0.25%。烟田生态系统对大气而言是弱碳汇,碳汇量116.13kghm?2。虽然烤烟固碳总量相对较低,但其根系对土壤碳贡献却相对较高。展开更多
精确预测大气 CO2 的未来变化对于预测全球气候变化是至关重要的。为此 ,需要确定大气 CO2 的源和汇及其随时间的变化。本文作者利用已发表和未发表的资料对一些实例进行了分析 :首先讨论了碳酸盐岩岩溶作用 (包括碳酸盐溶解及再沉积的...精确预测大气 CO2 的未来变化对于预测全球气候变化是至关重要的。为此 ,需要确定大气 CO2 的源和汇及其随时间的变化。本文作者利用已发表和未发表的资料对一些实例进行了分析 :首先讨论了碳酸盐岩岩溶作用 (包括碳酸盐溶解及再沉积的共同影响 )对土壤 CO2和径流变化的敏感性 ;接着利用水化学 -流量方法和碳酸盐岩石片试验方法得出了我国和世界碳酸盐岩地区因碳酸盐岩岩溶作用从大气中吸收的净 CO2 总量 ,即碳酸盐岩岩溶作用对大气 CO2 沉降的贡献。它们分别是 :中国每年 180 0万 t C,整个世界岩溶地区 1.1亿 t C;最后 ,文章据 DBL理论模型计算得出世界碳酸盐岩地区碳酸盐岩溶解吸收CO2 一项产生的大气 CO2 沉降量为每年 4 .1亿 t C,继而得出全世界碳酸盐岩地区因碳酸盐再沉积而释放 CO2 产生的大气 CO2 源项为每年 3亿 t C。展开更多
Different from the solution/physical pump, biological pump and continental shelf pump of carbon cycle in oceans, a new pump named “surface microlayer (SML) pump” is developed based on data obtained from marine inves...Different from the solution/physical pump, biological pump and continental shelf pump of carbon cycle in oceans, a new pump named “surface microlayer (SML) pump” is developed based on data obtained from marine investigations and lab study. The SML pump has: (1) left-right dissymmetry of “pH-depth” curve; (2) the non-linearity of “concentration-depth” curve; and (3) difference of affect-ing confine of the SML pump. The issue of “source” or “sink” of atmospheric CO2 in the Yellow Sea and South China Sea is discussed.展开更多
基金Financial supports for this research was provided by the National Nature Science Foundation of China(Grant 40073026)Ministry of Science and Technology of China(Grant 164)+1 种基金Natural Science Foundation of Guangxi(Grant 9824021)Ministry of Land and Resources of China(Grant 9806)and Bremen University of Germany.
文摘The conversion of CO2 into H+ and is a relatively slow reaction. Hence, its kinetics may be rate determining in carbonate rock dissolution. Carbonic anhydrase (CA), which is widespread in nature, was used to catalyze the CO2 conversion process in dissolution experiments of limestone and dolomite. It was found that the rate of dissolution increases by a factor of about 10 after the addition of CA at a high CO2 partial pressure (Pco2) for limestone and about 3 at low Pco2 for dolomite. This shows that reappraisal is necessary for the importance of chemical weathering (including carbonate rock dissolution and silicate weathering) in the atmospheric CO2 sink and the mysterious missing sink in carbon cycling. It is doubtless that previous studies of weathering underestimated weathering rates due to the ignorance of CA as an activator in weathering, thus the contribution of weathering to the atmospheric CO2 sink is also underestimated. This finding also shows the need to examine the situ distribution and activity of CA in different waters and to investigate the role of CA in weathering.
基金supported by the National Basic Research Program of China (973 Program) (No.2006CB403200)the Chinese National Natural Science Foundation (No.41403107 and No.41325010)+1 种基金the Basic Science Research Fund from the Institute of Hydrogeology and Environmental Geology (Grant No.SK200906 and SK201208)the China Geological Survey Projects (No.12120113005900)
文摘Fertilization and aglime(agricultural lime) application, as important agricultural activities in acid soil, exert an influence on the fluxes of carbon both between and within ecosystems. Animal manure added to soil can elevate the soil CO_2 and release organic acid due to microbial decomposition of the high organic matter content of animal manure. Additionally, the elevated CO_2 can accelerate carbonate weathering in alkaline soil, such as lime soil. However, in acidic soil, it is unclear whether the chemical weathering of additive aglime can be quickened by the elevated CO_2 due to animal manure addition. Thus, to ascertain the impact of animal manure addition on aglime weathering in acidic soil and to understand the weathering agent of aglime or underlying carbonate in the acidic soil profile, we established two contrasting profiles(control profile and manurial profile) in a cabbage-corn or capsicum-corn rotation in a field experiment site located in the Hua Xi district of Guiyang, China, and buried carbonate rock tablets at different depths of soil profiles to calculate the dissolution rate of carbonate rock by monitoring the weights of the tablets. The results indicated that soil CO_2 increased due to animal manure addition, but the rate of dissolution of the carbonate rock tablets was reduced, which was attributed to the increase in the p H in acidic soil after animal manure addition because the relationship between the dissolution rate of carbonate rock and soil p H indicated that the weathering rate of carbonate rock was controlled by pH and not by CO_2 in acidic soil. Thus, the contribution of H+ ions(mainly exchangeable acid) in acid soil as a weathering agent to the weathering of underlying carbonate(and/or aglime) may lead to the overestimation of the CO_2 consumption through chemical weathering at the regional/global scale using hydro-chemical methods.
基金funded by the National Natural Science Foundation of China[grant numbers 41630532,41975112,42175142,and 42175013].
文摘Over the past three decades,the drawdown of atmospheric CO_(2) in vegetation and soil has fueled net ecosystem production(NEP).Here,a global land-surface model(CABLE)is used to estimate the trend in NEP and its response to atmospheric CO_(2),climate change,biological nitrogen(N)fixation,and N deposition under future conditions from 2031 to 2100 in the Belt and Road region.The trend of NEP simulated by CABLE decreases from 0.015 Pg carbon(C)yr^(-2) under present conditions(1936–2005)to−0.023 Pg C yr^(-2) under future conditions.In contrast,the trend in NEP of the CMIP6 ensemble changes from 0.014 Pg C yr^(-2) under present conditions to−0.009 Pg C yr^(-2) under future conditions.This suggests that the trend in the C sink for the Belt and Road region will likely decline in the future.The significant difference in the NEP trend between present and future conditions is mainly caused by the difference in the impact of climate change on NEP.Considering the responses of soil respiration(RH)or net primary production(NPP)to surface air temperature,the trend in surface air temperature changes from 0.01℃ yr^(-1) under present conditions to 0.05℃ yr^(-1) under future conditions.CABLE simulates a greater response of RH to surface temperature than that of NPP under future conditions,which causes a decreasing trend in NEP.In addition,the greater decreasing trend in NEP under future conditions indicates that the C-climate-N interaction at the regional scale should be considered.It is important to estimate the direction and magnitude of C sinks under the C neutrality target.
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.
文摘农业生态系统碳平衡对评估陆地生态系统的源和汇具有重要意义,针对烤烟生长及管理的特殊性,研究烟田生态系统碳收支,为提升烟田管理及农业碳汇估算提供依据。本研究以定位试验为平台,以单施化肥处理为研究对象,于2015-2017年观测了烤烟生长季的碳收支。研究结果表明,烤烟生物量平均为(5832.10±537.32)kg hm?2;烟株碳含量平均为(42.14±0.05)%,累积固碳量为(2459.25±233.78)kg hm?2。烤烟根系碳占烟株碳比例较高,平均为24.94%。烤烟生长季湿沉降碳达到了115.32 kg hm?2,干沉降碳量为6.54 kg hm?2,两者占根系碳的20.01%。烟生长季碳输出总量为2464.98kghm?2,其中CO2排放碳占碳支出的98.99%,径流损失碳占支出的0.76%,淋溶损失碳占支出的0.25%。烟田生态系统对大气而言是弱碳汇,碳汇量116.13kghm?2。虽然烤烟固碳总量相对较低,但其根系对土壤碳贡献却相对较高。
文摘精确预测大气 CO2 的未来变化对于预测全球气候变化是至关重要的。为此 ,需要确定大气 CO2 的源和汇及其随时间的变化。本文作者利用已发表和未发表的资料对一些实例进行了分析 :首先讨论了碳酸盐岩岩溶作用 (包括碳酸盐溶解及再沉积的共同影响 )对土壤 CO2和径流变化的敏感性 ;接着利用水化学 -流量方法和碳酸盐岩石片试验方法得出了我国和世界碳酸盐岩地区因碳酸盐岩岩溶作用从大气中吸收的净 CO2 总量 ,即碳酸盐岩岩溶作用对大气 CO2 沉降的贡献。它们分别是 :中国每年 180 0万 t C,整个世界岩溶地区 1.1亿 t C;最后 ,文章据 DBL理论模型计算得出世界碳酸盐岩地区碳酸盐岩溶解吸收CO2 一项产生的大气 CO2 沉降量为每年 4 .1亿 t C,继而得出全世界碳酸盐岩地区因碳酸盐再沉积而释放 CO2 产生的大气 CO2 源项为每年 3亿 t C。
基金This work was supported by the Great Project of the National Natural Science Foundation of China (Grant No. 40490263)the National Natural Science Foundation of China (Grant Nos. 40076020, 40376022)+1 种基金 the research for the Doctoral Program for Higher Education (Grant No. 20030423007) the '973' National Basic Research Priorities Programme (Grant No. 2001CB409703).
文摘Different from the solution/physical pump, biological pump and continental shelf pump of carbon cycle in oceans, a new pump named “surface microlayer (SML) pump” is developed based on data obtained from marine investigations and lab study. The SML pump has: (1) left-right dissymmetry of “pH-depth” curve; (2) the non-linearity of “concentration-depth” curve; and (3) difference of affect-ing confine of the SML pump. The issue of “source” or “sink” of atmospheric CO2 in the Yellow Sea and South China Sea is discussed.
