Foliar Dust and Sentinel-2 Chlorophyll Retrievals: An Overlooked Challenge in Mining Landscapes

Accurate estimation of leaf chlorophyll concentration (LCC) using satellite remote sensing is essential for vegetation health assessment, particularly in environmentally stressed mining regions. However, foliar dust (FD) deposition alters leaf spectral reflectance and can reduce the reliability of satellite-derived chlorophyll products. This study investigates the influence of FD on Sentinel-2-based chlorophyll retrievals over a coal mining landscape in eastern India. In-situ LCC measurements and FD observations were collected from dusty and non-dusty vegetation plots, and their relationships were analyzed using Sentinel-2 spectral bands and vegetation indices. The study observed a complex non-linear relationship between FD and LCC, suggesting that vegetation response varies across different dust exposure levels. Sentinel-2 red-edge bands showed strong sensitivity to chlorophyll variations under dusty conditions, while several conventional vegetation indices exhibited reduced robustness. Empirical models developed using red-edge and shortwave infrared bands demonstrated improved agreement with field observations compared to globally trained chlorophyll retrieval approaches. In contrast, the Sentinel-2 SL2P processor consistently underestimated LCC in both dusty and non-dusty environments, although comparatively lower errors were observed under dusty conditions (Bias = −8.18 mg/cm²; nRMSE = 21.39%). This may indicate that foliar dust modified canopy spectral behaviour in a way that partially mimicked the spectral assumptions embedded within the globally trained SL2P model. The results further suggest that dust-induced spectral distortion can significantly influence chlorophyll estimation accuracy, especially in mining-affected environments. The findings emphasize the need for locally adapted remote sensing approaches for vegetation monitoring in industrial and dust-polluted landscapes. This study provides new insights into the FD–chlorophyll interaction and highlights the importance of considering dust effects in satellite-based ecological assessments across mining regions.