Characterization of marine microbial communities around an Arctic seabed hydrocarbon seep at Scott Inlet, Baffin Bay.

Seabed hydrocarbon seeps present natural laboratories for investigating responses of marine ecosystems to petroleum input. A hydrocarbon seep near Scott Inlet, Baffin Bay, was visited for in situ observations and sampling in the summer of 2018. Video evidence of an active hydrocarbon seep was confirmed by methane and hydrocarbon analysis of the overlying water column, which is 260 m at this site.

A New in Situ Method for Tracing Denitrification in Riparian Groundwater.

The spatiotemporal dynamics of denitrification in groundwater are still not well-understood because of a lack of efficient methods to quantify this biogeochemical reaction pathway. Previous research used the ratio of N to argon (Ar) to quantify net production of N via denitrification by separating the biologically generated N component from the atmospheric-generated components. However, this method does not allow the quantification of the atmospheric components accurately because the differences in gas partitioning between N and Ar are being neglected.

Continuous Measurements of Dissolved Ne, Ar, Kr, and Xe Ratios with a Field-Deployable Gas Equilibration Mass Spectrometer.

Noble gases dissolved in natural waters are useful tracers for quantifying physical processes. Here, we describe a field-deployable gas equilibration mass spectrometer (GEMS) that provides continuous, real-time measurements of Ne, Ar, Kr, and Xe mole ratios in natural waters. Gas is equilibrated with a membrane contactor cartridge and measured with a quadrupole mass spectrometer, after in-line purification with reactive metal alloy getters.