title: Selenium cycling across soil-plant-atmosphere interfaces: a critical review.
abstract: Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels.
authors.affiliation: Swiss Federal Institute of Technology (ETH), Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, CH-8092 Zurich, Switzerland. lenny.winkel@eawag.ch.|Eawag: Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf, Switzerland. lenny.winkel@eawag.ch.
authors.forename: Lenny H E
authors.initials: LH
authors.lastname: Winkel
authors.affiliation: Swiss Federal Institute of Technology (ETH), Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, CH-8092 Zurich, Switzerland. bas.vriens@eawag.ch.|Eawag: Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf, Switzerland. bas.vriens@eawag.ch.
authors.forename: Bas
authors.initials: B
authors.lastname: Vriens
authors.affiliation: Eawag: Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf, Switzerland. gerrad.jones@eawag.ch.
authors.forename: Gerrad D
authors.initials: GD
authors.lastname: Jones
authors.affiliation: Swiss Federal Institute of Technology (ETH), Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, CH-8092 Zurich, Switzerland. leilasc@student.ethz.ch.
authors.forename: Leila S
authors.initials: LS
authors.lastname: Schneider
authors.affiliation: Colorado State University, Biology Department, Fort Collins, CO 80523, USA. epsmits@lamar.colostate.edu.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pilon-Smits
authors.affiliation: USDA, Agricultural Research Service, San Joaquin Valley Agricultural Center, 9611 South Riverbend Avenue, Parlier, CA 93648, USA. gary.banuelos@ars.usda.gov.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Bañuelos
mesh_terms: D018556:Crops, Agricultural / Q000737:chemistry*; D004777:Environment; D018517:Plant Roots / Q000737:chemistry; D030821:Plants, Genetically Modified / Q000737:chemistry; D012643:Selenium / Q000032:analysis*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D012643:Selenium
keywords: atmosphere; biofortification; biomethylation; environment; hyperaccumulation; plants; selenium; soil; speciation