Spatiotemporal Variation Characteristics of Coal Dust Pollution in the Baorixile Mining Area
Coal dust from open-pit mining severely impacts the mining area and surrounding environment, exhibiting significant dynamic changes. However, quantitative assessments of the pollution extent and multi-timescale evolution remain insufficient. Based on the Google Earth Engine platform and Landsat TM/ETM+/OLI/OLI-2 and Sentinel-2 MSI imagery from 2001 to 2024, we retrieved the enhanced coal dust index (ECDI) and coal dust pollution levels. Combined with the mine lifecycle stages, we revealed the temporal and spatial variations of coal dust in the Baorixile mining area. Annual and monthly remote sensing retrievals were stacked to construct multi-year and intra-annual dust impact frequency (DIF) indicators, precisely quantifying the spatial extent and frequency of coal dust pollution. Results show that from 2001 to 2024, the interannual coal dust pollution experienced three stages: fluctuating increase, significant decrease, and stabilization. The average pollution degree peaked at 0.41 in 2010 and remained between 0.18 and 0.22 from 2016 to 2024. The spatial pattern improved, converging from widespread diffusion to the open-pit and bare coal accumulation areas. From 2019 to 2023, intra-annual pollution increased then decreased, with summer most severe, followed by autumn, spring, and winter. Based on annual retrievals, 6 periods of multi-year DIF (2001-2024) were generated at 4-year intervals. The maximum impact range (DIF≥1) first expanded then contracted significantly; the perennial impact area (DIF=4) shifted from the southeast to the central-western open-pit, indicating a notable migration of dust disturbance gravity and effective control. Based on monthly retrievals, 6 periods of intra-annual DIF (2019-2024) were generated at 12-month intervals. The intra-annual DIF showed a gradient decreasing from the core operation area to the periphery. High-frequency zones (DIF≥9) were stably concentrated in the open-pit. The affected area fluctuated downward from 88.14 km² in 2019 to 72.84 km² in 2024. This study provides theoretical and data support for scientifically understanding and monitoring the ecological status of mining areas and formulating dust suppression measures.