title: Selenium biogeochemical cycling and fluxes in the hyporheic zone of a mining-impacted stream.
abstract: The influence of hyporheic exchange on selenium (Se) biogeochemistry and mobility in sediments is unknown. A multiscale investigation of Se biogeochemistry in the hyporheic zone of East Mill Creek (EMC), southeastern Idaho, USA, was performed using in situ surface water and pore water geochemical measurements, a field-based stream tracer test, and energy-dependent micro synchrotron X-ray fluorescence (mu-SXRF) measurements of Se speciation in sediments. The active hyporheic zone was determined to be 12 +/- 3 cm. Pore water redox profiles indicated that a transition to suboxic conditions begins at approximately 6 cm. Modeling pore water Se and solid phase analysis suggested Se uptake is occurring. Micro-SXRF analysis of sediments showed reduced elemental Se or selenides throughout the profile and selenite in surface sediments. Field geochemical measurements and microscale analysis both support the hypothesis that reduction in the hyporheic zone promotes sequestration of surface water Se.
authors.affiliation: Environmental Sciences Program, and Plant, Soil and Entomological Sciences Department, University of Idaho, Moscow, Idaho 83844-2339, USA.
authors.forename: Libbie L
authors.initials: LL
authors.lastname: Oram
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Strawn
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Morra
authors.forename: Gregory
authors.initials: G
authors.lastname: Möller
mesh_terms: D007061:Idaho; D008906:Mining; D012643:Selenium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D012643:Selenium