title: Evaporation as the transport mechanism of metals in arid regions.
abstract: Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust.
authors.affiliation: Department of Earth Sciences, Division of Geochemistry, Utrecht University, PO Box 80.021, 3508 TA Utrecht, The Netherlands; Ecohydrology, Department of Earth and Environmental Sciences, University of Waterloo, Waterloo N2L 3G1, Canada. Electronic address: atlima@uwaterloo.ca.
authors.forename: Ana T
authors.initials: AT
authors.lastname: Lima
authors.affiliation: Department of Earth Sciences, Division of Geochemistry, Utrecht University, PO Box 80.021, 3508 TA Utrecht, The Netherlands.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Safar
authors.affiliation: Department of Earth Sciences, Division of Geochemistry, Utrecht University, PO Box 80.021, 3508 TA Utrecht, The Netherlands.
authors.forename: J P Gustav
authors.initials: JP
authors.lastname: Loch
mesh_terms: D003889:Desert Climate; D055864:Droughts; D019216:Metals, Heavy / Q000032:analysis*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D014835:Volatilization; D014867:Water / Q000737:chemistry
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D014867:Water
keywords: Arid regions; Dust; Heavy metals; Soil; Transport by evaporation