A regional chemical transport model,RAMS-CMAQ,was employed to assess the impacts of biosphere-atmosphere CO2 exchange on seasonal variations in atmospheric CO2 concentrations over East Asia.Simulated CO2 concentration...A regional chemical transport model,RAMS-CMAQ,was employed to assess the impacts of biosphere-atmosphere CO2 exchange on seasonal variations in atmospheric CO2 concentrations over East Asia.Simulated CO2 concentrations were compared with observations at 12 surface stations and the comparison showed they were generally in good agreement.Both observations and simulations suggested that surface CO2 over East Asia features a summertime trough due to biospheric absorption,while in some urban areas surface CO2 has a distinct summer peak,which could be attributed to the strong impact from anthropogenic emissions.Analysis of the model results indicated that biospheric fluxes and fossil-fuel emissions are comparably important in shaping spatial distributions of CO2 near the surface over East Asia.Biospheric flux plays an important role in the prevailing spatial pattern of CO2 enhancement and reduction on the synoptic scale due to the strong seasonality of biospheric CO2 flux.The elevation of CO2 levels by the biosphere during winter was found to be larger than 5 ppm in North China and Southeast China,and during summertime a significant depletion (≥ 7 ppm) occurred in most areas,except for the Indo-China Peninsula where positive bioflux values were found.展开更多
Carbon dioxide injection into deep saline aquifers results in a variety of strongly coupled physical and chemical processes. In this study, reactive transport simulations using a 2-D radial model were performed to inv...Carbon dioxide injection into deep saline aquifers results in a variety of strongly coupled physical and chemical processes. In this study, reactive transport simulations using a 2-D radial model were performed to investigate the fate of the injected CO2, the effect of CO2-water-rock interactions on mineral alteration, and the long-term CO2 sequestration mechanisms of the Liujiagou Formation sandstone at the Shenhua CCS(carbon capture and storage) pilot site of China. Carbon dioxide was injected at a constant rate of 0.1 Mt/year for 30 years, and the fluid flow and geochemical transport simulation was run for a period of 10 000 years by the TOUGHREACT code according to the underground conditions of the Liujiagou Formation. The results show that different trapping phases of CO2 vary with time. Sensitivity analyses indicate that plagioclase composition and chlorite presence are the most significant determinants of stable carbonate minerals and CO2 mineral trapping capacity. For arkosic arenite in the Liujiagou Formation, CO2 can be immobilized by precipitation of ankerite, magnesite, siderite, dawsonite, and calcite for different mineral compositions, with Ca(2+), Mg(2+), Fe(2+) and Na+ provided by dissolution of calcite, albite(or oligoclase) and chlorite. This study can provide useful insights into the geochemistry of CO2 storage in other arkosic arenite(feldspar rich sandstone) formations at other pilots or target sites.展开更多
基金supported by the Strategic Priority Research Program–Climate Change: Carbon Budget and Relevant Issues (Grant No. XDA05040404)the National High Technology Research and Development Program of China (Grant No. 2013AA122002)+1 种基金the National Natural Science Foundation of China (Grant No. 41130528)support staff of the stations for providing their CO2 observation records on the WDCGG website
文摘A regional chemical transport model,RAMS-CMAQ,was employed to assess the impacts of biosphere-atmosphere CO2 exchange on seasonal variations in atmospheric CO2 concentrations over East Asia.Simulated CO2 concentrations were compared with observations at 12 surface stations and the comparison showed they were generally in good agreement.Both observations and simulations suggested that surface CO2 over East Asia features a summertime trough due to biospheric absorption,while in some urban areas surface CO2 has a distinct summer peak,which could be attributed to the strong impact from anthropogenic emissions.Analysis of the model results indicated that biospheric fluxes and fossil-fuel emissions are comparably important in shaping spatial distributions of CO2 near the surface over East Asia.Biospheric flux plays an important role in the prevailing spatial pattern of CO2 enhancement and reduction on the synoptic scale due to the strong seasonality of biospheric CO2 flux.The elevation of CO2 levels by the biosphere during winter was found to be larger than 5 ppm in North China and Southeast China,and during summertime a significant depletion (≥ 7 ppm) occurred in most areas,except for the Indo-China Peninsula where positive bioflux values were found.
基金supported by the Global Climate and Energy Project(No.2384638-43106-A)the National Natural Science Foundation of China(No.41072180)+1 种基金the Special Scientific Research Fund of Public Welfare Profession of the Ministry of Land and Resources of China(No.201211063)a bilateral project of China Australia Geological Storage of CO2 Project Phase 2(CAGS2)
文摘Carbon dioxide injection into deep saline aquifers results in a variety of strongly coupled physical and chemical processes. In this study, reactive transport simulations using a 2-D radial model were performed to investigate the fate of the injected CO2, the effect of CO2-water-rock interactions on mineral alteration, and the long-term CO2 sequestration mechanisms of the Liujiagou Formation sandstone at the Shenhua CCS(carbon capture and storage) pilot site of China. Carbon dioxide was injected at a constant rate of 0.1 Mt/year for 30 years, and the fluid flow and geochemical transport simulation was run for a period of 10 000 years by the TOUGHREACT code according to the underground conditions of the Liujiagou Formation. The results show that different trapping phases of CO2 vary with time. Sensitivity analyses indicate that plagioclase composition and chlorite presence are the most significant determinants of stable carbonate minerals and CO2 mineral trapping capacity. For arkosic arenite in the Liujiagou Formation, CO2 can be immobilized by precipitation of ankerite, magnesite, siderite, dawsonite, and calcite for different mineral compositions, with Ca(2+), Mg(2+), Fe(2+) and Na+ provided by dissolution of calcite, albite(or oligoclase) and chlorite. This study can provide useful insights into the geochemistry of CO2 storage in other arkosic arenite(feldspar rich sandstone) formations at other pilots or target sites.