Street Dust Pollution Of Typical Cities In Shenyang Economic Zone

With the rapid development of urban economy and the continuous expansion of urban scale, urban environment pollution is attracting more and more attention from the public. Urban street dust is a typical urban environmental pollutant, which has played the role of the media in urban environmental pollution, and has strong links with urban air, water and soil contamination. Urban street dust is solid particle that accumulates on the surface of the city road or street. On the one hand, street dust can re-float due to the wind or traffic disturbance, and enters the atmosphere in the form of suspended particles or settles down in urban soil again. On the other, street dust can enter rivers or lakes in the scouring action of rain. No matter how street dust re-enter the urban environment, it will definitely cause secondary pollution to the urban environment.Shenyang Economic Zone is China’s new industrialized comprehensive reform pilot area, the cities within which have typical characteristics of old industrial bases, and street dust pollution characteristics are closely associated with the region’s urban population health. In Shenyang Economic Zone, only preliminary study on urban street dust has been carried out in Shenyang while researches on street dust pollution in other cities were not yet conducted. In order to fill these blanks about research, Shenyang, Fushun, Tieling were selected as study objects in this paper, and the physical and chemical properties, content, spatial distribution and the degree of pollution of heavy metals, as well as content and the spatial distribution of ammonia, nitrate and dissolved organic carbon in urban street dust from these three cities were analyzed, which are not only important for maintaining good urban environment to protect the urban population, but also can provide a reliable scientific basis for the pollution prevention and quality assessment of urban environment, as well as urban planning.The main conclusions of this paper are as follows:(1) Street dust in Shenyang, Fushun, Tieling were alkaline, with the mean value of p H 8.39, 7.87, 7.80 respectively.(2) Coarse particles accounted for the largest proportion, more than 50%, in street dust in Shenyang, Fushun, Tieling, indicating that skip migration is probably the main way to move for street dust particles in these three cities(3) the average contents of Cu in Shenyang, Tieling, Fushun street dusts were 88.2 mg/kg, 64.1 mg/kg, 48.9 mg/kg, respectively;the average contents of Cd were 1.9 mg/kg, 2.1 mg/kg, 1.4 mg/kg, respectively; the average contents of Pb were 70.1 mg/kg, 101.1 mg/kg, 82.6 mg/kg, respectively; the average contents of Zn were 231.1 mg/kg, 167.9 mg/kg, 150.8 mg/kg, respectively; the average contents of Mn were 1225.0 mg/kg, 1000.6 mg/kg, 659.6 mg/kg, respectively. And the mean values of these heavy metals in street dust from these three cities were significantly higher than the soil background values. In addition, content of Cu, Zn, Mn in Shenyang street dust were higher than that of Fushun and Tieling, but the highest content of Pb was found in Fushun street dust, followed Tieling, and Shenyang was the minimum. Content of Cd in Shenyang, Fushun, Tieling street dust showed little difference, with the descending order: Fushun> Shenyang> Tieling.(4) According to the potential ecological hazard index, street dust in Shenyang, Fushun, Tieling were slightly polluted by Cu, Pb, Zn, Mn, while seriously polluted by Cd The total ecological hazard index of heavy metals Cu, Cd, Pb, Zn, Mn in street dust in these three city maintained a high level due to the pollution levels of Cd, with Shenyang and Fushun are highly contaminated, followed by Tieling. At the same time, the geo-accumulation index results indicated that the pollution levels of Cu, Pb, Zn in street dust of Shenyang were moderate, and the pollution level of Mn was slight to moderate, while Cd was strong to extreme; that the pollution levels of Cu, Mn in street dust of Fushun were slight to moderate, and the pollution levels of Pb, Zn were moderate, while Cd was strong to extreme; that the pollution levels of Cu, Zn in street dust of Tieling were slight to moderate, and the pollution levels of Pb, Mn, Cd were moderate, little, strong, respectively.(5) High values of Cu, Cd, Pb, Zn in street dust of Shenyang, Fushun, Tieling occurred at train stations, bus terminals, commercial areas, as well as industrial and mining enterprises, which showed that these heavy metals might be significantly influenced by road traffic, human activities and industrial and mining enterprises. Although the distribution of Mn was not the same as Cu, Cd, Pb, Zn, the content of Mn was still affected by industrial and urban activities.(6) The mean contents of NH3-N in street dust in Shenyang, Fushun, Tieling were 35.04 mg/kg, 8.45 mg/kg, 26.86 mg/kg, and the average contents of NO3-N were 58.62 mg/kg, 8.89 mg/kg, 25.00 mg/kg。Obviously, the NH3-N and NO3-N levels in street dust of these three cities were in the decreasing order: Shenyang>Tieling>Fushun. High values of NH3-N in street dust of Shenyang, Fushun, Tieling were detected in the streets near the park, indicating that the main source of NH3-N in street dust was possibly urban soil, while High values of NO3-N often occurred in the streets near parks, train stations, or commercial areas where traffic loads and human activities were relatively high, indicating that their contents may be subject to the combined impacts of urban soil, road traffic, and human activities.(7) The average contents of DOC in street dust in Shenyang, Fushun, Tieling were 542.55 mg/kg, 223.04 mg/kg, 392.06 mg/kg, with the descending order: Shenyang>Tieling>Fushun. Similar to the case of NO3-N, high values of DOC often occurred in the streets near parks, train stations, or commercial areas where traffic loads and human activities were relatively high, indicating that their contents may be also influenced by urban soil, road traffic, as well as human activities.