Effect of Deicing Salts on Urban Soils and the Health of Roadside Pines (Pinus tabulaeformis) in Northeast China

Accumulation of high concentrations of Na and Cl ions in soils is one factor that hampers plant establishment along roadsides in regions where deicing salts are used to improve winter driving conditions. However, there is little information on the accumulation of deicing salts in roadside soil as well as on the phytotoxic impact of deicing salts on pines in Northeast China. The accumulation of salt in soil and injuries on pine needles (Pinus tabulaeformis) were investigated in the urban areas of Shenyang city in 2011. The results showed that the use of deicing salts on roads leads to the high accumulation of sodium (352–513 mg•kg-1) and chloride (577–2,353 mg•kg-1) in urban roadside soil. High pH and EC values suggested that the alkaline status and high soluble salts in the soil. High accumulation of deicing salts in roadside soil has been shown to have a phytotoxic effect on pines (Pinus tabulaeformis). Concentrations of Na and Cl in leaves were higher in the roadside plants than the plants appearing healthy in control site. The accumulation of Na and Cl in the needles were present up to an average of 274 mg•kg-1 (24–672 mg•kg-1) and 3,681 mg•kg-1 (786–9,919 mg•kg-1), respectively. It is evident that the deicing salts spray has a significant effect on the accumulation of sodium and chloride in urban roadside soils and needles of Pinus tabulaeformis, as well as the occurrence of visible injuries.

Assessment of Heavy Metal Pollution of Urban Roadside Soil with Set Pair Analysis and Geoaccumulation Index

The assessment of pollution levels of heavy metals soil contamination is significant to the health of human kind. Two methods, Set Pair Analysis (SPA) and Geoaccumulation Index (Igeo), are applied to assess the urban roadside soil heavy metals pollution levels and compare the assessment results with Fuzzy Comprehensive Analysis (FCA). The assessment results of SPA are inconsistent with the FCA. The ranks of roadside soil heavy metals, assessed by Igeo, indicate that the result of FCA is determined by most contaminated heavy metal, the SPA is determined by the contents distribution of all elements. The mean and standard deviation of heavy metal content in research soils are applied to establish an assessment standard and this method is also applicable if there is lower differentiation rate or no uniform standards.

PIXE ANALYSIS OF URBAN ROADSIDE SOIL

In order to study the influence of motor vehicles on a local soil environment, depth profiles of elemental concentration of urban roadside soil were investigated by means of thick-target PIXE analysis. For comparison, we analyzed the soil sampled in a university campus with very low traffic intensity. From the measured depth profiles, it was found that the roadside surface layers up to the depth of approximately 5 cm from the ground level are highly polluted by S and Zn. According to cluster analysis this pollution can be attributed to the deposition of tire dust due to the heavy vehicular traffic volumes on the highways.