| 英文摘要 |
Starting from 18 October 2020 to 17 May 2021, four aeolian dust control measures including the xanthan gum spraying (207.54 hectares), grass planting (5.63 hectares), tree planting (3.32 hectares), and clam shells coverage (10.37 hectares/701.72 tons) were taken to mitigate the possible effects of aeolian dust on local air quality. To quantify the effects of these control measures on aeolian dust, horizontal sand/saltation flux monitoring were applied. Results showed that aeolian dust suppression efficiency for xanthan gum spraying, grass planting, tree planting, and clam shells coverage were 80.1%, 97.1%, 99.4%, and 89.1%, respectively. Grass and tree planting had the best performance on the suppression of aeolian dust, following by clam shells coverage. Xanthan gum spraying had lower effects on the suppression of aeolian dust. Overall, the suppression efficiency of four aeolian dust control measures was higher than 80%.
It was observed that xanthan gum spraying could reduce aeolian dust immediately but would not be able to last long. The advantages of flexibility and quick implementation has made it the best emergency response measure. Grass planting showed the great ability to suppress aeolian dust and could last more than one year. The measure is suitable to be applied before the northeast monsoon season. Tree planting is a long-term measure, which requires longer time to grow. It is suggested to grow the trees during spring or summer with high water level. Clam shells coverage could reduce the production of aeolian dust for months and helped promote the growth of plants, which is suitable to be applied before the northeast monsoon season.
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, Shiuguang, and Yishian Station showed that the aeolian dust suppression efficiencies under high wind velocity (potential to cause aeolian dust cases) were all higher than 34.1%, and the aeolian dust cases were 67.1% lower than predicted cases based on the condition in 2018 and 2019. Therefore, the control measures indeed showed the ability to suppress the emission of aeolian dust in Zhuoshui River.
To realize the influence on level of aeolian dust to different leeward areas before and after “Zhuoshui River’s Action Plan for Aeolian Dust Control and Improvement”, AERMOD Modeling System (Air Quality Dispersion Modeling) were applied. Results showed that the influence on level of aeolian dust decreased progressively from the bare lands of Zhuoshui River toward southwest side. After the Action Plan, the reduction of PM10 in Xiluo Area was higher than 90% and the reduction of PM10 in Mailiao and Lunbei was 70-90%.
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