title: Roadside soils show low plant available zinc and copper concentrations.
abstract: Vehicle combustion and component wear are a major source of metal contamination in the environment, which could be especially concerning where road ditches are actively farmed. The objective of this study was to assess how site variables, namely age, traffic (vehicles day(-1)), and percent carbon (%C) affect metal accumulation in roadside soils. A soil chronosequence was established with sites ranging from 3 to 37 years old and bioavailable, or mobile, concentrations of Zinc (Zn) and Copper (Cu) were measured along major highways in North Carolina using a Mehlich III extraction. Mobile Zn and Cu concentrations were low overall, and when results were scaled via literature values to "total metal", the results were still generally lower than previous roadside studies. This could indicate farming on lands near roads would pose a low plant toxicity risk. Zinc and Cu were not correlated with annual average traffic count, but were positively correlated with lifetime traffic load (the product of site age and traffic count). This study shows an often overlooked variable, site age, should be included when considering roadside pollution accumulation. Zinc and Cu were more strongly associated with %C, than traffic load. Because vehicle combustion is also a carbon source, it is not obvious whether the metals and carbon are simply co-accumulating or whether the soil carbon in roadside soils may facilitate previously overlooked roles in sequestering metals on-site.
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University, 111 Wing Drive, B62 Riley Robb Hall, Ithaca, NY, 14850, United States. Electronic address: nrb75@cornell.edu.
authors.forename: Natalie
authors.initials: N
authors.lastname: Morse
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University, 111 Wing Drive, B62 Riley Robb Hall, Ithaca, NY, 14850, United States. Electronic address: mtw5@cornell.edu.
authors.forename: M Todd
authors.initials: MT
authors.lastname: Walter
authors.affiliation: Department of Soil Science, North Carolina State University, P.O. Box 7619, Raleigh, NC, 27695, United States. Electronic address: dosmond@ncsu.edu.
authors.forename: Deanna
authors.initials: D
authors.lastname: Osmond
authors.affiliation: Department of Biological and Agricultural Engineering, North Carolina State University, P.O. Box 7625, Raleigh, NC, 27695, United States. Electronic address: wfhunt@ncsu.edu.
authors.forename: William
authors.initials: W
authors.lastname: Hunt
mesh_terms: D000383:Agriculture; D003300:Copper / Q000032:analysis* / Q000378:metabolism; D004784:Environmental Monitoring; D009657:North Carolina; D010944:Plants / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism; D001335:Vehicle Emissions / Q000032:analysis; D015032:Zinc / Q000032:analysis* / Q000378:metabolism
chemical_list: D012987:Soil; D012989:Soil Pollutants; D001335:Vehicle Emissions; D003300:Copper; D015032:Zinc
keywords: Copper; Highway; Soil pollution; Traffic; Zinc