Geospatial Distribution of Metal Elements in Transportation Land Use Surficial Soils

Abstract

Highway traffic generates heavy metals and particulate matter through various vehicular and tire-pavement abrasion mechanisms. These abraded materials are deposited, they accumulate, and they are transported by storm water. Soils subject to years of such loading can serve as a sink and a potential source for heavy metals. The results of geotechnical analyses, heavy metal distributions, drainage influences, and correlations to geotechnical indices for surficial (0 to 15 cm) glacial till samples recovered from two transects along a heavily traveled urban interstate highway were compared with a control site subjected to only urban atmospheric deposition. This investigation indicated, for this site, that heavy metal accretion in the surficial soils is a function of depth, surface drainage patterns, distance from the pavement edge, and soil indices. Particulate-bound heavy metal deposition and accretion or export were a function of surface flow conditions such as velocity, flow depth, and surface cover. Results indicated that heavy metal accretion rapidly decreases as a function of distance from the traveled roadway. Along the longitudinal transect, correlations between heavy metals and soil organic content were statistically significant, particularly for copper. Along the transverse transect, correlations between soil plasticity, organic content, and heavy metals were statistically significant. Although there is little control of traffic levels and past accretion, indices such as soil organic content and plasticity index, as well as pavement runoff surface drainage patterns, can provide information about whether highway soils might act as a sink or source of heavy metals and, consequently, if best management practices may be justified.

Traffic-Related Heavy Metal Contamination in Urban Areas and Correlation with Traffic Activity in China

“…A total of 319 topsoil samples were collected in May 2014 to reflect the different land use and traffic conditions. In general, more heavy metals accumulated in soil between 0 and 5 cm than at other depths, and concentrations were found to be very low when depths were greater than 10-15 cm (2,21). Thus, the top 10 cm of soil were used for the study.…”

“…The coordinates of the sample locations were recorded with GPS. To compare the heavy metal concentrations in different areas and exclude the effects of air deposition or runoff on the heavy metal contamination, the background values, which represented concentrations of elements in natural materials exclud ing human activity, were obtained by sampling and analyzing items that were subjected to air deposition or runoff only and had not been disturbed by human activity, such as plants far away from the urban area and control borings made by thinwalled steel tubes (2).…”

“…Engine oil consumption is responsible for the largest emission of Cd, tire wear is responsible for the largest emission of Zn, and brake wear produces the most Cu and Pb emissions (13). Though the use of unleaded gasoline has caused a subsequent reduc tion in fuel emission of Pb, it may still occur in selected gasoline blends, in batteries, and as an anticaking agent for deicing salts (2). Deicing salts that are employed on highways and roads often con tain chlorine because of their costeffectiveness; the main salts used are sodium chloride, magnesium chloride, and calcium chloride (14,15).…”

“…Environmental awareness and sustainable development are growing concerns in both developed and developing countries (1). For instance, soils in the urban environment have been and will be subjected to heavy metal loadings, and the accumulation of heavy metals in urban soils has a strong relationship with human activities (2). Emissions of heavy metals may come from transportation, industry, and domestic waste (3).…”