Crop Residue burning from high-resolution satellite imagery and PM 2.5 dispersion: A case study of Mississippi County, Arkansas, USA

Crop residue burns typically result in particulate matter (PM2.5), methane (CH4), carbon monoxide (CO), nitrous oxide (N2O), nitrogen oxides (NOx), volatile organic carbon (VOC), and black carbon emissions, which affect air quality and can pose a risk to public health. Currently, Arkansas farmers self-regulate crop burning using voluntary smoke management guidelines to reduce community impacts from smoke by ensuring burns take place in optimal conditions. The aim of this study is to identify burned cropland areas and examine human-caused fire PM2.5 emissions and dispersion during optimal burn conditions, specifically within Mississippi County, Arkansas, USA, using two separate methods. During the 2019 harvest season, high-resolution satellite data was used to manually identify burned areas and crop types. The total cumulative cropland burned area in 2019 was estimated to be 7,137 acres (29.03 km2). Burning harvested rice fields accounted for approximately 35% of the total annual PM2.5 emissions from all annual agricultural burning as reported in the 2017 U.S. EPA National Emissions Inventory, while PM2.5 emissions from burning corn fields were only 8% of the total estimated annual PM2.5 emissions. Approximately 43% of annual agricultural burning PM2.5 emissions occurred between 15 August and 23 October in Mississippi County. These high-resolution burned areas were not captured in the standard coarse resolution active fire products. Secondly, during the 2020 fall harvest season, we measured PM2.5 emissions using a Purple Air sensor and modeled smoke dispersion from a planned burn of rice fields following state-level voluntary guidelines. Additionally, the smoke transport model HYSPLIT was deployed to model this planned burn. The HYSPLIT results suggest that smoke disperses into the atmosphere from burns following the guidelines, limiting ground-level human exposure under optimal burning conditions.