Effective CO2 sequestration is crucial for mitigating climate change, and dawsonite-bearing sandstone reservoirs are considered potential geological storage sites for CO2. In this process, the interactions among CO2, H2O, and rock directly influence the precipitation and dissolution of carbon-bearing minerals within the dawsonite-bearing sandstone, thereby affecting the stability of carbon sequestration. This study focuses on natural dawsonite-bearing sandstone from the Dongying sag. We conduct physical experiments in a high-temperature, high-pressure reactor to investigate the CO2-H2O-dawsonite-bearing sandstone interaction under different temperatures and CO2 pressures. X-ray diffraction, scanning electron microscopy, energy spectrum analysis, and water chemical analysis were employed to systematically investigate the dissolution and precipitation characteristics of the sandstone samples. Additionally, thermodynamic simulations were performed using the PHREEQC numerical simulation software, facilitating an understanding of the stable states of the reaction system under different conditions. The results indicate that the dissolution of dawsonite tablets leads to the formation of gibbsite and boehmite, which can transform into kaolinite under certain conditions. Temperature and CO2 pressure exert significant effects on these processes. Notably, the CO2-H2O-dawsonite-bearing sandstone reaction system remains stable under high CO2 pressure and exhibits strong carbon fixation ability. This research provides valuable insights for assessing the feasibility and safety of CO2 geological sequestration and storage.
The Xinzhou geothermal field, situated within the Xinzhou Basin of northern China, represents a classic hydrothermal system with substantial development and utilization potential. To characterize the distribution of the geothermal system in this region, we deployed an integrated electromagnetic survey network comprising 98 Magnetotelluric (MT) stations and 226 Controlled-Source Electromagnetic (CSEM) stations. Through the application of three-dimensional MT inversion techniques and two-dimensional CSEM inversion methodologies, we constructed a comprehensive electrical conductivity model of the region, revealing the distinctive electrical characteristics of the deep subsurface structures. The crustal structure within the study area can be vertically subdivided into three primary stratigraphic units. The uppermost unit (C1), composed of Quaternary and Neogene sedimentary sequences, presents as a low-resistivity layer with thickness varying from 20 to 360 m. Within this layer, anomalous conductive zones associated with clay alteration zones have been identified. The intermediate unit, predominantly consisting of Archaean metamorphic rocks, manifests as a high-resistivity layer (R1), which contains three distinct low-resistivity anomalies (C2–C4). These anomalous bodies, characterized by resistivity values below 40 Ω·m, are interpreted as geothermal reservoirs located at depths ranging from 0.5–3 km. The basal unit comprises an extensive low-resistivity layer (C5), primarily situated at depths between 6–12 km. This layer is interpreted as an indirect heat source for the geothermal field, with estimated temperatures ranging from 195 to 420 °C. The formation of this heat source is likely attributed to crust-mantle thermal conduction processes. Distinct thermal conduits exist between the heat source and the geothermal reservoirs, characterized by relatively low resistivity features that are closely associated with concealed fault systems in the region. These conduits facilitate heat transfer within the system. This comprehensive investigation not only delineates the spatial distribution of the Xinzhou geothermal system but also provides crucial technical support for the sustainable development and utilization of geothermal resources in the region.
The Guanzhong Basin, located in Shaanxi Province, China, has abundant geothermal resources in its hinterland. Focusing on typical thermal reservoir structural units, namely the Xianli fault-step (XL) and Xi’an depression (XA), this study reveals the genesis of geothermal water by combining hydrochemistry and environmental isotopes. The geothermal waters of XL uniformly correspond to the Na-Cl type with high contents of major ions, while the geothermal water of XA has complex hydrochemical types. The quartz geothermometer (with maximum steam loss) and the Na-K-Ca geothermometer are recommended for XL and the quartz geothermometer (with no and maximum steam loss) and the Na-K geothermometer for XA. Their temperature ranges are 99–159 and 93–146 °C, respectively. The circulation depth of geofluids in the XL and XA ranges from 2 579 to 4 766 m and from 2 541 to 4 330 m, with mean apparent ages of 21 543 and 20 345 yr B.P., respectively. The geothermal water in XL originates from a mixture of sedimentary water and ancient infiltration water, and its formation mode is vertical heat conduction with a cooling process. In contrast, the geothermal water in XA originates from the dual process of cooling and mixing, with the process being dominated by ancient infiltration water and supplemented by modern infiltration water.
Drought resilience is essential for reducing the economic impacts of drought, yet its role has been underutilized in drought loss models. This study develops a novel drought loss function that, for the first time, explicitly incorporates drought resilience into direct economic loss estimations and quantifies its impact. By employing a drought resilience index (DRI) constructed from 56 indicators across six domains, this study quantifies the impact of resilience across China from 1994 to 2020. The results showed significant improvements in the accuracy of drought loss simulations, with errors reduced to a range of 6.34
Nitrogen pollution is a major cause of lake eutrophication, garnering global concern for its detrimental impact on lake water quality. However, the intricate interplay between lakes and groundwater in the accumulation and release of nitrogen remains largely overlooked. Using Honghu Lake as a case study, a large lake in the Yangtze River Basin long plagued by nitrogen pollution, this study analyzed the temporal shifts in its water area from 1990 to 2021 using remote-sensing image classification algorithms. From 1990 to 2005, the natural water area of Hong Lake decreased by 72
