Soil inorganic carbon(SIC)accounts for about half of the C reserves worldwide and is considered more stable than soil organic carbon(SOC).However,soil acidification,driven mainly by nitrogen(N)fertilization can accele...Soil inorganic carbon(SIC)accounts for about half of the C reserves worldwide and is considered more stable than soil organic carbon(SOC).However,soil acidification,driven mainly by nitrogen(N)fertilization can accelerate SIC losses,possibly leading to complete loss under continuous and intensive N fertilization.Carbonate-free soils are less fertile,productive,and more prone to erosion.Therefore,minimizing carbonate losses is essential for soil health and climate change mitigation.Rock/mineral residues or powder have been suggested as a cheaper source of amendments to increase soil alkalinity.However,slow mineral dissolution limits its efficient utilization.Soil microorganisms play a vital role in the weathering of rocks and their inoculation with mineral residues can enhance dissolution rates.Biochar is an alternative material for soil amendments,in particular,bone biochar(BBC)contains higher Ca and Mg that can induce even higher alkalinity.This review covers i)the contribution and mechanism of rock residues in alkalinity generation,ii)the role of biochar or BBC to soil alkalinity,and iii)the role of microbial inoculation for accelerating alkalinity generation through enhanced mineral dissolution.We conclude that using rock residues/BBC combined with microbial agents could mitigate soil acidification and SIC losses and also improve agricultural circularity.展开更多
Biological carbon pumping(BCP)is a key process in which dissolved inorganic carbon in terrestrial aquatic ecosystems is utilized by aquatic autotrophs for photosynthesis and transformed into autochthonous organic matt...Biological carbon pumping(BCP)is a key process in which dissolved inorganic carbon in terrestrial aquatic ecosystems is utilized by aquatic autotrophs for photosynthesis and transformed into autochthonous organic matter(AOC).However,the mechanisms underlying BCP and the amount of generated AOC deposited effectively,are still poorly understood.Therefore,we conducted a systematic study combining modern hydrochemical monitoring and a sediment trap experiment in Fuxian Lake(Yunnan,SW China),the second-deepest plateau,oligotrophic freshwater lake in China.Temperature,pH,EC(electrical conductivity),DO(dissolved O2),[HCO3^-],[Ca^2+],SIc,partial CO2(pCO2)pressure,and carbon isotopic compositions of HCO3^-(δ^13CDIc)in water from Fuxian Lake all displayed distinct seasonal and vertical variations.This was especially apparent in an inverse correlation between pCO2 and DO,indicating that variations of hydrochemistry in the lake water were mainly controlled by the metabolism of the aquatic phototrophs.Furthermore,the lowest C/N ratios and highestδ^13Corg were recorded in the trap sediments.Analyses of the C/N ratio demonstrated that the proportions of AOC ranged from 30%to 100%of all OC,indicating that AOC was an important contributor to sedimentary organic matter(OC).It was calculated that the AOC flux in Fuxian Lake was 20.43 t C km^-2 in 2017.Therefore,AOC produced by carbonate weathering and aquatic photosynthesis could potentially be a significant carbon sink and may have an important contribution to solving the lack of carbon sinks in the global carbon cycle.展开更多
The weathering of carbonate rocks by biological soil crusts （BSC） in karst areas is very common. It is helpful to understand the weathering mechanisms and processes for avoiding karst rock-desertification. The weath...The weathering of carbonate rocks by biological soil crusts （BSC） in karst areas is very common. It is helpful to understand the weathering mechanisms and processes for avoiding karst rock-desertification. The weathering of carbonate rocks by BSC in karst areas, namely the expansion, contraction and curl resulting from environmental wetting-drying cycles, was investigated and ana- lyzed in this paper. The bulk density, area and thickness of BSC were determined and the weathering amount of limestone and dolomite per unit area of BSC was calculated as 3 700 and 3 400 g·m-2; the amount of biomass on the surface of limestone and dolomite was calculated as 1 146 and 1 301 g·m-2, respectively. Such an increased weathering amount was not only the result of chemical and physical weathering of BSC on carbonate rocks, but also the attachment and cementation of BSC to clay particles, dust-fall, sand particles, solid particles brought by strong air currents, wind and other factors in the surrounding environment, which may also be related to the special environment and the special time period. Based on the results obtained, a weathering mode of BSC is studied, and the mechanisms of weathering by BSC are discussed. In conclusion, we suggest that the mechanical force exerted by the expansion and constriction of gelatinous and mucilaginous substances through wetting and drying of BSC play a significant role in the physical weathering process of the carbonate substrates.展开更多
基金The research funds were supported by the Chinese Academy of Sciences under President’s International Fellowship for Postdo-ctoral Researchers Program(PIFI)(Grant No.2021PE0052).
文摘Soil inorganic carbon(SIC)accounts for about half of the C reserves worldwide and is considered more stable than soil organic carbon(SOC).However,soil acidification,driven mainly by nitrogen(N)fertilization can accelerate SIC losses,possibly leading to complete loss under continuous and intensive N fertilization.Carbonate-free soils are less fertile,productive,and more prone to erosion.Therefore,minimizing carbonate losses is essential for soil health and climate change mitigation.Rock/mineral residues or powder have been suggested as a cheaper source of amendments to increase soil alkalinity.However,slow mineral dissolution limits its efficient utilization.Soil microorganisms play a vital role in the weathering of rocks and their inoculation with mineral residues can enhance dissolution rates.Biochar is an alternative material for soil amendments,in particular,bone biochar(BBC)contains higher Ca and Mg that can induce even higher alkalinity.This review covers i)the contribution and mechanism of rock residues in alkalinity generation,ii)the role of biochar or BBC to soil alkalinity,and iii)the role of microbial inoculation for accelerating alkalinity generation through enhanced mineral dissolution.We conclude that using rock residues/BBC combined with microbial agents could mitigate soil acidification and SIC losses and also improve agricultural circularity.
基金supported by the National Natural Science Foundation of China (Nos. 41430753, U1612441)
文摘Biological carbon pumping(BCP)is a key process in which dissolved inorganic carbon in terrestrial aquatic ecosystems is utilized by aquatic autotrophs for photosynthesis and transformed into autochthonous organic matter(AOC).However,the mechanisms underlying BCP and the amount of generated AOC deposited effectively,are still poorly understood.Therefore,we conducted a systematic study combining modern hydrochemical monitoring and a sediment trap experiment in Fuxian Lake(Yunnan,SW China),the second-deepest plateau,oligotrophic freshwater lake in China.Temperature,pH,EC(electrical conductivity),DO(dissolved O2),[HCO3^-],[Ca^2+],SIc,partial CO2(pCO2)pressure,and carbon isotopic compositions of HCO3^-(δ^13CDIc)in water from Fuxian Lake all displayed distinct seasonal and vertical variations.This was especially apparent in an inverse correlation between pCO2 and DO,indicating that variations of hydrochemistry in the lake water were mainly controlled by the metabolism of the aquatic phototrophs.Furthermore,the lowest C/N ratios and highestδ^13Corg were recorded in the trap sediments.Analyses of the C/N ratio demonstrated that the proportions of AOC ranged from 30%to 100%of all OC,indicating that AOC was an important contributor to sedimentary organic matter(OC).It was calculated that the AOC flux in Fuxian Lake was 20.43 t C km^-2 in 2017.Therefore,AOC produced by carbonate weathering and aquatic photosynthesis could potentially be a significant carbon sink and may have an important contribution to solving the lack of carbon sinks in the global carbon cycle.
基金supported by the National Key Basic Research Program of China (No. 2013CB956702)the National Natural Science Foundation of China (No. 41373078)
文摘The weathering of carbonate rocks by biological soil crusts （BSC） in karst areas is very common. It is helpful to understand the weathering mechanisms and processes for avoiding karst rock-desertification. The weathering of carbonate rocks by BSC in karst areas, namely the expansion, contraction and curl resulting from environmental wetting-drying cycles, was investigated and ana- lyzed in this paper. The bulk density, area and thickness of BSC were determined and the weathering amount of limestone and dolomite per unit area of BSC was calculated as 3 700 and 3 400 g·m-2; the amount of biomass on the surface of limestone and dolomite was calculated as 1 146 and 1 301 g·m-2, respectively. Such an increased weathering amount was not only the result of chemical and physical weathering of BSC on carbonate rocks, but also the attachment and cementation of BSC to clay particles, dust-fall, sand particles, solid particles brought by strong air currents, wind and other factors in the surrounding environment, which may also be related to the special environment and the special time period. Based on the results obtained, a weathering mode of BSC is studied, and the mechanisms of weathering by BSC are discussed. In conclusion, we suggest that the mechanical force exerted by the expansion and constriction of gelatinous and mucilaginous substances through wetting and drying of BSC play a significant role in the physical weathering process of the carbonate substrates.
