Spectral reflection characteristics of sea ice polluted by pulverized coal in the Bohai Sea

Many studies have been conducted on the environmental pollution caused by pulverized coal on land and related monitoring methods; however, few studies have been conducted on the monitoring of pulverized coal pollution on sea ice. In this study, experiments were conducted on natural sea ice in the Bohai Sea of China to obtain the spectral reflectance of sea ice contaminated by different quantities of pulverized coal. The reflection characteristics of sea ice and pulverized coal particles were analyzed using these in-situ measurements, and it was determined that the reflection characteristics of a mixed sea ice-pulverized coal pixel could be described by the linear mixed pixel model. The proportions of pulverized coal surface area on ten sea ice samples were then determined by evaluating the average reflectivity in the 1600-1630 nm wide band using the linear mixed pixel model with an absolute error of 0.23 and a maximum relative error of 16.53%. Notably, the errors were generally larger for pixels with smaller portions of pulverized coal surface area. By overcoming the influence of sea ice background reflectivity, the proposed method of estimating the surface area of pulverized coal particles in mixed sea ice-pulverized coal pixels was found to be accurate. This study provides important basic data and feasible methods for large-scale remote monitoring of pulverized coal on the surface of sea ice using multispectral or hyperspectral infrared bands, and provides technical support for the supervision of environmental pollution near ports.