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Arid Land Geography ›› 2021, Vol. 44 ›› Issue (2): 379-388.doi: 10.12118/j.issn.1000–6060.2021.02.09

• Earth Surface Process • Previous Articles     Next Articles

Spatial distribution of particle fractionations of dust and soil in the valley-city of northwest China

GAO Yu1,2(),LI Xiaoping1,2(),ZHANG Yuchao1,2,CAO Yuhan1,2,LI Tao1,2,YANG Tao1,2,WANG Lijun1,2   

  1. 1. Department of Environment Sciences, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
    2. International Joint Research Center of Shaanxi Province for Pollution Exposure and Ecoenvironment Health,Xi’an 710062, Shaanxi, China
  • Received:2019-12-15 Revised:2021-01-18 Online:2021-03-25 Published:2021-04-14
  • Contact: Xiaoping LI E-mail:gaoyu1911@snnu.edu.cn;lixiaoping@snnu.edu.cn

Abstract:

Both Lanzhou and Yan’an are valley cities in northwest China that are critical for the petrochemical industry and energy and have frequent dusty weather. The fine particles and dust in the soil easily enter the atmosphere and cause haze pollution. However, basic data, such as urban soil characteristics and dust particle size in this area are lacking. This study collected soil and dust samples in the main urban area of Lanzhou and Yan’an. The particle size composition was measured using a laser particle size analyzer. The environmental effects were analyzed through spatial distribution and particle size of soil and dust. We provide scientific data and a theoretical basis for the urban environmental protection in Lanzhou and Yan’an. The results show that the principal size fractions of soil and dust in Lanzhou and Yan’an were no more than 100 μm. The overall grain size distribution trend decreased as silty clay (<50 μm) > impalpable sand (50-100 μm) > fine sand (100-250 μm) > medium sand (250-500 μm) > coarse medium sand (500-1000 μm). The proportion of dust particle size less than 100 μm in Lanzhou is 69.17%, which was larger than in Yan’an (53.49%). The results indicate that the fractionation in dust of less than 100 μm was easy to increase under an external power condition and become the potential source of pollution and human health risk. The results of spatial distributions of PM1, PM2.5, and PM10 in soil and dust showed that the same size of urban soil in the upper wind direction was a source of urban dust under the same size wind direction. Furthermore, industrial activities significantly influence small-sized soils, and frequent human activities significantly influence small-sized dust. Correlation analysis was conducted using Spass 21 software on a proportion of different particle levels between soil dust in Lanzhou and Yan’an, respectively. A significant correlation exists between different soil and dust particle levels in Lanzhou, with a correlation coefficient of r=0.967, which is a strong correlation. A significant correlation also exists between soil and dust in Yan’an, with r=0.767, indicating that soil fine particles might partly contribute to dust.

Key words: soil and dust, particle size distribution, environment effect, Lanzhou City, Yan’an City