Rural Aerosol Characteristics During Agricultural Tillage in Northeast China: Insights from Six-Site Ambient Monitoring

Agricultural tillage-emitted atmospheric particulate matter (PM) substantially impacts aerosol loading, with cascading effects on climate, environment, and human health. However, rural aerosol characteristics and agricultural PM emission magnitudes remain unclear across distinct agricultural regions. To determine the spatio-temporal variations and driving factors of rural aerosols, this study conducted a three-month field measurement at six monitoring sites in Northeast China, differing in crop system, farming practices, and soil type. Key data included real-time PM_2.5 and PM₁₀ concentrations, daily ambient PM_2.5 samples analyzed for chemical compositions (ions, elements, and carbonaceous fractions), and vertical aerosol extinction profiles. Results revealed significant spatial heterogeneity in tillage-period PM_2.5 concentrations (80–237) µg/m³, with dryland-dominated regions exhibiting the highest levels (up to (237 ± 189)) µg/m³ and paddy-concentrated areas the lowest (80 ± 16) µg/m³. These spatial differences were primarily driven by meteorological conditions and tillage practices, with low humidity ( ~ 10%) and high wind speeds (>7 m/s) jointly enhancing PM concentrations, and large-scale machinery producing the highest instantaneous emissions. Ions accounted for 3.1%–23.3% of PM_2.5, with higher proportions at urban-proximal sites (Shenyang, Changchun) and the lowest at the most remote site (Sanjiang). Elements contributed a maximum of 8.9% to PM_2.5 at Da’an, attributed to arid conditions and soil degradation/salinization. Total carbon (i.e., organic and elemental carbon) constituted 10.5%–18.2% of PM_2.5, with elevated ratios at dry crop-dominated, spring-burning-prone sites (Hailun, Yushu). Vertically, the saline-alkali site (Da’an) exhibited notably higher near-surface aerosol extinction coefficients with large fluctuations, indicating severe soil fugitive dust from tillage in degraded farmlands. These findings provide a systematic understanding of rural aerosol characteristics and support the development of region-specific mitigation strategies.