Wind-tunnel and modelled PM10 emissions and dust concentrations from agriculture soils in Tianjin, northern China

Wind erosion that can cause significant economic and environmental damage represents a serious problem in northern China. Dust emitted from agriculture soil is a major source of ambient PM10, in the study area of Tianjin. The objectives of this study were to estimate the PM10 emission potential from agriculture soils extrapolated from a wind tunnel study, and to compare its result with Chemical Mass Balance (CMB) model. Five representative soil samples (one sample for each soil type) collected from erodible croplands in Tianjin were studied in a wind tunnel under the selected free stream velocities of 4, 6, 8, 10 and 12 m/s. PM10 concentrations upstream and downstream of the soils were measured by aerosol monitors to calculate emission rate and threshold wind speed of PM10 Emission rate, accumulative hour when wind speed was over wind threshold, and bare ground area of soils were used to calculate total emission amount of PM10 attributed to soil erosion. The results indicated that PM10 emission increased with increasing wind speed and sampling height from soil surface. The total emission amount from soils was estimated to be 23,080 t in Tianjin. Spring period featured the highest PM10 emission due to its higher and sustained wind speed. The average PM10 concentrations predicted by Community Multi-scale Air Quality (CMAQ) model were 3.2, 8.0, 3.6 and 6.6 mu g/m(3) for heating period, sand period, non-heating period and the whole year, respectively. These values correlated with the results obtained by CMB model, indicating that the proposed method for estimating PM10 emission amount based on wind tunnel experiment was reliable.