Local PM10 and PM2.5 emission inventories from agricultural tillage and harvest in northeastern China.

Mineral particles or particulate matters (PMs) emitted during agricultural activities are major recurring sources of atmospheric aerosol loading. However, precise PM inventory from agricultural tillage and harvest in agricultural regions is challenged by infrequent local emission factor (EF) measurements. To understand PM emissions from these practices in northeastern China, we measured EFs of PM10 and PM2.5 from three field operations (i.e., tilling, planting and harvesting) in major crop production (i.e., corn and soybean), using portable real-time PM analyzers and weather station data. County-level PM10 and PM2.5 emissions from agricultural tillage and harvest were estimated, based on local EFs, crop areas and crop calendars. The EFs averaged (107±27), (17±5) and 26mg/m2 for field tilling, planting and harvesting under relatively dry conditions (i.e., soil moisture <15%), respectively. The EFs of PM from field tillage and planting operations were negatively affected by topsoil moisture. The magnitude of PM10 and PM2.5 emissions from these three activities were estimated to be 35.1 and 9.8 kilotons/yr in northeastern China, respectively, of which Heilongjiang Province accounted for approximately 45%. Spatiotemporal distribution showed that most PM10 emission occurred in April, May and October and were concentrated in the central regions of the northeastern plain, which is dominated by dryland crops. Further work is needed to estimate the contribution of agricultural dust emissions to regional air quality in northeastern China.