The aeolian dust of Zhuoshui River caused by northeast monsoon is a long-standing issue. To mitigate the possible effects of aeolian dust on local air quality, four aeolian dust control measures including the xanthan gum spraying (93.43 hectares), clam shells coverage (20.12 hectares), gravel coverage (3.12 hectares), and shrub planting (5.13 hectares) were taken. To quantify the effects of these control measures on aeolian dust, transportable monitoring and wind tunnel experiment were applied. Results of transportable monitoring showed that aeolian dust suppression efficiency for xanthan gum spraying, clam shells coverage, gravel coverage, and shrub planting were 76.6%, 59.0-72.1%, 7.4%, and 8.5%, respectively. Xanthan gum had the best performance on the suppression of aeolian dust, while gravel coverage and shrub had no obvious effects. Wind tunnel experiment results showed that xanthan gum spraying (1,200 liter/hectare) had the best suppresstion efficiency (PM2.5 , PM10 , and PN ), following by clam shells coverage and shrub planting. The gravel coverage and xanthan gum spraying (600 liter/hectare) had lower suppression efficiency. Overall, the suppression efficiency of four aeolian dust control measures was higher than 77%.
It was observed that xanthan gum spraying could reduce aeolian dust immediately but would not be able to last long. Clam shells coverage could reduce the production of aeolian dust for months and helped promote the growth of plants. Gravel coverage on the contrary wind helped reduce the fugitive dust when vehicles were passing by, while the unit cost was the highest among these control measures. There is no obvious reduction of aeolian dust for shrub planting due to time requirement for shrub to grow.
The historical data of air quality monitoring stations were further analyzed to evaluate the comprehensive effectiveness of overall control measures taken during this year. Results of Mailiao Station showed that the aeolian dust suppression efficiency under high wind velocity (potential to cause aeolian dust cases) was 52.3%, and the aeolian dust cases were 52.5% lower than predicted cases based on the condition in 2017. Results of Shiuguang Station showed that the aeolian dust suppression efficiency under high wind velocity (potential to cause aeolian dust cases) was 41.6%, and the aeolian dust cases were 37.5% lower than predicted cases based on the condition in 2017. Therefore, the control measures (water coverage, sand bar watering system, clam shells coverage, and xanthan gum spraying etc.) indeed showed the ability to suppress the emission of aeolian dust in Zhuoshui River.
