DOI: 10.21963/13279
title: Stream and river summertime water quality, carbon, nutrients, isotopes, gases, and constituent export in 33 permafrost-affected watersheds across 4 eco-regions in the western Canadian Arctic (June-August, 2015)

description: This compilation of stream water quality, chemistry, and flux data is intended to support estimates of ecosystem carbon balance across four varied ecoregions in the western Canadian Arctic, in order to investigate physiographic controls underlying regional variation in biogeochemical cycling and implications for climate feedbacks in thawing permafrost terrains. Arctic stream water samples were collected during summer 2016 from 33 sites in the Yukon Territory and Northwest Territories in Canada. Sites were located along the regional Dempster Highway corridor. Water samples were collected up to three times at all 33 stream sites in the Yukon in Northwest Territories from June–August, 2016, using triple sample-rinsed 1 L high-density polyethylene bottles and/or polypropylene syringes. The following text summarizes the variables and units. Air temperature (˚C); atmospheric pressure (atm), water temperature (˚C), specific conductance (µS/cm), dissolved oxygen concentration (%), dissolved oxygen concentration (mg/L), and stream water pH (pH units); CO2 and CH4 concentration in stream water and atmosphere (ppm); stream water concentrations of dissolved inorganic carbon (DIC), bicarbonate and carbonate, dissolved organic carbon (DOC), cations (calcium, magnesium, sodium, potassium) and trace metals (iron, aluminum), anions (sulfate, chloride), total and inorganic nitrogen, organic nitrogen, particulate total and organic carbon and nitrogen, particulate inorganic carbon (all dissolved and particulate constituents in µM); total suspended solids (mg/L); specific UV absorbance at 254 nm (L/mgC/m); spectral slope ratio (unitless), stable isotopic composition of dissolved inorganic carbon and dissolved organic carbon(‰); stable isotopic composition of H and O in water (‰); d-excess (unitless); stream width and depth (m); stream flow velocity (m/s); instantaneous efflux (vertical flux from stream to the atmosphere) of CO2 (µmol/m2/s) and CH4 (nmol/m2/s); upscaled daily efflux (vertical flux from stream to the atmosphere) of CO2 (µmol/m2/d) and CH4 (nmol/m2/d); instantaneous lateral downstream fluxes of CO2 and CH4, bicarbonate, DOC, DIC, particulate organic carbon, particulate inorganic carbon, total carbon (all in mmol/s); upscaled daily yield of all previously listed dissolved and particulate constituents (all in µmol/m2/d) (calculated as flux / watershed area).
description: Recent models indicate disproportionate future carbon emissions from abrupt permafrost thaw features, which are widespread across the circumpolar north and occupy only a fractional area of this vast terrain. Yet, hydrologic export of thawed permafrost carbon is hypothesized to significantly offset the terrestrial component of net ecosystem carbon balance. Progress toward understanding these feedbacks to global climate change is limited by a scarcity of observational studies which quantify hydrologic carbon fluxes and underlying physiographic drivers across thaw-susceptible terrains. To reduce this uncertainty, in this study we directly measured summertime water quality, carbon, nutrients, isotopes, gases, and constituent export in 33 watersheds across a physiographic transect in the western Canadian Arctic which intersects a global hotspot of abrupt permafrost thaw. The overarching objective of this research is to to understand how geology and landscape evolution since the last glacial maximum have shaped modern-day variation in aquatic carbon sources, fluxes, and ecosystem carbon balance.