01847nas a2200193 4500008004100000022001400041245005200055210005200107260001200159300001400171490000700185520124200192100002201434700002901456700002401485700001501509700001701524856011201541 2018 eng d a0091-761300aBarium and barite dynamics in Antarctic streams0 aBarium and barite dynamics in Antarctic streams c08/2018 a811 - 8140 v463 a

Most natural waters are undersaturated with respect to barite (BaSO4), and while much work has focused on the processes of microbially mediated barite precipitation in undersaturated solutions, particularly in marine environments, little documentation exists on the changes in barite saturation in stream waters. We examined ephemeral glacial meltwater streams in the McMurdo Dry Valleys, Antarctica, that undergo large variations in streamflow and temperature on both a diel and seasonal basis. We measured dissolved Ba in stream water in downstream transects and on a diel cycle, total Ba in stream sediments, algal mats, and lake sediments. Ba concentrations decreased downstream in all four transects, and mineral saturation modeling indicates these waters go from supersaturated to undersaturated with respect to barite in very short distances. Ba is concentrated in stream benthic algal mats at a factor less than observed in marine systems. Both seasonal and diel changes in stream water temperature affect the solubility of barite near glacial sources. Our work shows that both changing stream temperature and the presence of algal materials likely play significant roles in controlling Ba concentrations in polar streams.

1 aSaelens, Elsa, D.1 aGardner, Christopher, B.1 aWelch, Kathleen, A.1 aWelch, Sue1 aLyons, Berry uhttps://pubs.geoscienceworld.org/gsa/geology/article/545184/Barium-and-barite-dynamics-in-Antarctic-streams02094nas a2200241 4500008004100000245014400041210006900185260001200254490000600266520131100272653002001583653001401603653001701617653001501634653001501649653002401664653001301688653002201701100001701723700002201740700002401762856006601786 2018 eng d00aThe impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited0 aimpact of fossil fuel burning related to scientific activities i c04/20180 v63 a

 

Fossil fuel use associated with scienti c activities in the Taylor Valley, Antarctic has been examined to determine the fluxes of particulate organic and elemental carbon and nitrogen as well as NOx for the 2015–2016 austral summer field season. These carbon and nitrogen fluxes are compared to our previously published calculations for the 1997–1998 austral summer. In addition, we compile fossil fuel usage and resulting C and N fluxes from the major field camp in Taylor Valley, Lake Hoare Camp (LHC) from the late 1990’s through 2017. In general, the annual fluxes do vary from year to year, but there is no significant trend, at least during the primary summer field season. There is indication that increasing the length of scientific operations does increase the C and N inputs via fossil fuel burning. This works supports our original results demonstrating that over long periods of time the anthropogenic flux of N from local fossil fuel burning could become quantitatively important in the region. Although the particulate C fluxes remain very low, the recent finding of black carbon in the Taylor Valley landscape indicates more on-going monitoring of the source of this material is merited.

 

10acarbon dynamics10aemissions10afossil fuels10ahelicopter10amanagement10aMcMurdo Dry Valleys10anitrogen10ascience activites1 aLyons, Berry1 aSaelens, Elsa, D.1 aWelch, Kathleen, A. uhttps://www.elementascience.org/article/10.1525/elementa.288/00489nas a2200121 4500008004100000245011200041210006900153260004400222490000900266100002200275700001700297856005300314 2017 eng d00aThe geochemistry of minor cations within Antarctic stream water: Determining the role of the hyporheic zone0 ageochemistry of minor cations within Antarctic stream water Dete aColumbus, OHbThe Ohio State University0 vB.A.1 aSaelens, Elsa, D.1 aLyons, Berry uhttp://library.ohio-state.edu/record=b8218699~S7