title: Effects of aging on the fraction distribution and bioavailability of selenium in three different soils.
abstract: Aging refers to the processes by which the mobility and bioavailability of metals in soil decline with time. Although long-term aging is a key process that needs to be considered in risk assessment of metals, few investigations has been attempted to determine whether and how residence time influences the selenium (Se) fractions and bioavailability in soil. In this study, the fractions of Se in soils was evaluated, and bioavailability were assessed by measuring Se concentration in pak choi (Brassica chinensis L.). Results showed that the change of soil available Se in all tested soils divided into two phases: rapid decrease at the initial time (42 d) and slow decline thereafter. The second-order equation could describe the decrease processes of available Se in tested soils during the entire incubation time (R(2) > 0.99), while parabolic diffusion equation had less goodness of fit. Those results indicated that Se aging was controlled not only by diffusion process but also by other processes such as nucleation/precipitation, adsorption/desorption with soil component, occlusion by organic matter and reduction reaction. Soil available Se fractions tended to transform to more stable fractions during aging. The changes of Se concentration in pak choi were consistent with the variation in soil available Se content. In addition, 21 d could be reference for the time of Se aging reaching stabilization in krasnozems and fluvo-aquic soil, and 30 d for black soil. Results could provide theoretical basis to formulate environmental quality criterion and choose the equilibrium time before implementing a pot experiment in Se-spiked soils.
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Peng
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China. Electronic address: dlliang@nwsuaf.edu.cn.
authors.forename: Dongli
authors.initials: D
authors.lastname: Liang
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
authors.forename: Sijie
authors.initials: S
authors.lastname: Liang
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Chen
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Sun
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
authors.forename: Shuqi
authors.initials: S
authors.lastname: Li
authors.affiliation: College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
authors.forename: Penghui
authors.initials: P
authors.lastname: Lei
mesh_terms: D000327:Adsorption; D001682:Biological Availability; D001937:Brassica / Q000378:metabolism; D012643:Selenium / Q000737:chemistry* / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D013997:Time Factors
chemical_list: D012987:Soil; D012643:Selenium
keywords: Aging; Bioavailability; Fraction; Se; Soil