查看更多>>摘要：? 2021Carbon dioxide storage in geological formations is one of the mature strategies developed for controlling global warming. This paper represents a comprehensive experimental and geochemical modeling study to analyze CO2-brine-rock interactions in a carbonate rock containing calcite and dolomite minerals. PHREEQC geochemical package has been applied for modeling the geochemical reactions in the studied porous media. Firstly, dynamic experiments are performed to calibrate the geochemical model. Then, static experiments are conducted to study the geochemical reactions in the CO2-brine-rock interaction system. This study contributes to analyzing the precipitation-dissolution and ion exchange mechanisms in the CO2-brine- carbonate rock reactions during carbon dioxide storage. The purpose of the present paper is providing a scientific basis to judge surface CO2 loading in carbonate reservoirs. Results of the present study show that brine-rock interaction increases the dissolution of carbon dioxide gas in the aqueous phase. It is also demonstrated that carbonate ions can attach to the minerals' surface through the ion exchange mechanism. Among the surface ion exchangers, >CaHCO3 contains the maximum amount of carbonate ion. At the high pressures, amount of the carbon dioxide stored on the minerals' surface is almost independent of the pressure variation.
查看更多>>摘要：? 2022 Elsevier B.V.Lake sediments are important archives of environmental changes and human activities, but the influences of human processes and lake spatial heterogeneity on the sedimentation of trace metals are still poorly understood. Based on 16 sediment cores from Lake Erhai (249 km2), trace metals (including As and Hg) contamination over the past century and the spatial heterogeneity and their response to the in-lake and in-watershed factors were explored. The elements were divided into two groups by cluster analysis: group I included As, Cd, Hg and Pb, and group II included Al, Fe, Ti, Cr, Cu, Ni and Zn. The element concentrations were generally stable in the low section of the cores, and started to increase since the 1980s for elements in group I, while element concentrations in group II generally decreased since the 1990s. Enrichment factor analyses identified group I elements as typical pollutants, and suggested that contamination started from the 1980s and reached maximum in the 2000s. Regional atmospheric deposition from ore mining and smelting was the main source, and anthropogenic As and Cd were also affected by watershed industrial discharges. Multi-core analyses indicated that spatial distributions and accumulation of As, Cd, Hg and Pb in the cores were affected by both human activities and sediment supply. Different from metal contamination pattern in surface sediments, high anthropogenic metal fluxes appeared in the central lake areas due to more sediment accumulation. Our study highlighted that reliable estimation of whole-lake pollutant inventories strongly relied on comprehensive analyses of multiple sediment cores and legacy input from the catchment.
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