In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the s...In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.展开更多
Water-soluble organic acid anions(WSOAA)in subsurface water have been intensively studied during past several decades.They are used as natural gas precursor,tracer for the movement of underground fluid,indicator for p...Water-soluble organic acid anions(WSOAA)in subsurface water have been intensively studied during past several decades.They are used as natural gas precursor,tracer for the movement of underground fluid,indicator for porosity improvement,and detecter of deep subsurface life on the Earth.However,little is known about the distributions and origins of organic acids at deep-ultradeep depth underground.Herein,we collected twenty-nine source rock samples covering a wide maturity range from the Ordos,Qinshui,Junggar,Minhe,and Southern North China basins,as well as six subsurface water samples with depth between 6544 and 8396 m from industrial gas producing wells in the Tarim Basin,China.We carried out pyrolysis experiments at various temperatures(250–450℃)to investigate the role of water on the generation of organic acids.Results show that there are considerable amounts of WSOAA detected in both high-over mature source rocks and deep-ultradeep subsurface water.WSOAA mainly consists of monocarboxylates,predominately formate and acetate.High-TOC oil-generating source rock has low production rate of organic acids due to lack of hydrogen.Different source rocks have distinct ratios of formate to acetate concentration,expressed as c(formate)/c(acetate),which is due to significant differences in both initial molecular structure and metabolite.This indicates that c(formate)/c(acetate)can be used to distinguish types of organic matters(OMs).Concentrations of WSOAA show a“sharp decrease-slight increase-slow decrease”evolution trend with progressive maturity.Moreover,there are higher production rates of organic acids under hydrous pyrolysis experiments at≥400℃.All geochemical signatures indicate that at both deep-ultradeep depth and high-over mature stages,the formation of organic acids is attributed to the thermochemical oxidation of organic components by mainly hydroxyl radicals,challenging the traditional model of organic acid evolution.This work suggests that petroleum exploration can be extended to great depths in sedimentary basins,when formation temperatures are not exceeding 230℃.展开更多
基金Under the auspices of Chinese Academy Sciences Action Plan for the Development of Western China(No.KZCX2-XB3-10)Major State Basic Research Development Program of China(No.2011BAC09B02)+2 种基金Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues'of Chinese Academy of Sciences(No.XDA05070404,XDA05050205)National Natural Science Foundation of China(No.31070425,31000224,U1033004)Guangxi Provincial Program of Distinguished Expert in China
文摘In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.
基金supported by the National Nature Science Foundation of China(Nos.42203027,U2244209,41872147)the China Postdoctoral Science Foundation(No.2023M730039).
文摘Water-soluble organic acid anions(WSOAA)in subsurface water have been intensively studied during past several decades.They are used as natural gas precursor,tracer for the movement of underground fluid,indicator for porosity improvement,and detecter of deep subsurface life on the Earth.However,little is known about the distributions and origins of organic acids at deep-ultradeep depth underground.Herein,we collected twenty-nine source rock samples covering a wide maturity range from the Ordos,Qinshui,Junggar,Minhe,and Southern North China basins,as well as six subsurface water samples with depth between 6544 and 8396 m from industrial gas producing wells in the Tarim Basin,China.We carried out pyrolysis experiments at various temperatures(250–450℃)to investigate the role of water on the generation of organic acids.Results show that there are considerable amounts of WSOAA detected in both high-over mature source rocks and deep-ultradeep subsurface water.WSOAA mainly consists of monocarboxylates,predominately formate and acetate.High-TOC oil-generating source rock has low production rate of organic acids due to lack of hydrogen.Different source rocks have distinct ratios of formate to acetate concentration,expressed as c(formate)/c(acetate),which is due to significant differences in both initial molecular structure and metabolite.This indicates that c(formate)/c(acetate)can be used to distinguish types of organic matters(OMs).Concentrations of WSOAA show a“sharp decrease-slight increase-slow decrease”evolution trend with progressive maturity.Moreover,there are higher production rates of organic acids under hydrous pyrolysis experiments at≥400℃.All geochemical signatures indicate that at both deep-ultradeep depth and high-over mature stages,the formation of organic acids is attributed to the thermochemical oxidation of organic components by mainly hydroxyl radicals,challenging the traditional model of organic acid evolution.This work suggests that petroleum exploration can be extended to great depths in sedimentary basins,when formation temperatures are not exceeding 230℃.
