High-resolution simulations of particulate matter emitted by different agriculture tillage under different weather conditions in California, USA

Agriculture tillage can result in the high concentration of particulate matter with an aerodynamic diameter of 10 mu m or less (PM(10)) that can cause serious health problems. To understand how different agriculture tillage methods and wind conditions affect the transmission and distribution of PM(10), four model runs were performed using the high resolution Weather Research and Forecasting model coupled with a chemistry component (WRF-Chem). In these runs, the observed emission rates under the conventional and combined tillage methods and different wind speeds were inputted into WRF-Chem. The simulated results show that the WRF-Chem model can reasonably capture the meteorological conditions at 500 m horizontal resolution over an agricultural field in California. The atmospheric concentration of particulate matter increases significantly with an increase in the emission area. Substantial reduction, 50%, of aerosolized PM(10) dust emissions can be achieved by using combined tillage, when considered under the same meteorological conditions when compared to that caused by the conventional tillage method. Using the same conventional tillage emission rates, the lower velocity wind produces larger airborne concentrations of pollutants than does a stronger wind. Conversely, a stronger wind distributes the particulate matter over a larger area though with a diminished concentration when compared to a weaker wind. The atmospheric concentration of particulate matter was found to have a direct relationship to its emission intensity and area and wind conditions.