2012 Optical properties of Dissolved Organic Matter (DOM) in headwater catchments, Cape Bounty, Melville Island, Nunavut

Sites information NAD 27 UTM 12x: Ptarmigan (PT): 0540596, 8314704 ; Goose (GS): 0540900, 8314197 ; Caribou (CR): 0540280, 8315140 ; ALD05 (ALD): 0540679,8134265. Samples named by site abbreviation, date (MMDD) and time: PT0714 1300 = Ptarmigan July 14th at 1 pm. Samples were vacuum filtered using a glass filtration apparatus and precombusted 0.7 µm GF/F glass fibre filters. The samples were stored cool in the dark (refrigerated) in amber glass EPA vials, and acidified to a pH of 2 upon return to the laboratory. UV-visible absorbance and fluorescence measurements and Emission Excitation Matrices (EEMs) were collected at room temperature using a Horiba Aqualog. Each sample was run individually in 1-cm path length quartz cuvette. Absorbance spectra were blank-corrected using Milli-Q water. UV-visible absorbance spectra and excitation values were collected between 240-600 nm at 3 nm intervals and emission wavelengths were scanned from 214.16 - 621.03 nm at 3.15 nm intervals. EEMs files were corrected for blanks and inner filter effects, 1st and 2nd order Rayleigh scatter effects were removed. The signal was normalized using a 1 ppm Quinone Sulfate standard, made up in 0.05M H2SO4, and run daily during measurements, to account for fluctuations in the instrument light source characteristics. All intensities were reported in terms of Quinone Sulfate Units (QSU).

Eight optical indices from absorbance and fluorescence spectra were calculated: Napieran absorption coefficients (E in m-1) ; Absorption coefficient at 350 nm (E350 in m-1) ; Specific UV Absorbance (SUVA254 in l.mg-1-C.m-1) ; Absorption spectra slopes were calculated over two spectral bands 275-295 (S295) and 350-400 nm (S400) and the slope ratio (SR) was calculated as the ratio between the two spectral slopes ; The Fluorescence Index (FI), which was calculated as the ratio of emission at 470 to 520 m at an excitation wavelength of 370 nm ; The Freshness Index (BIX) is calculated as the ratio of emission at 380 nm divided by the emission intensity maximum observed between 420 and 435 nm at an excitation wavelength of 310 nm ; The Humification Index (HIX), which indicates the humic substance content or extent of humification, was calculated as the area under the emission spectra 435–480 nm divided by the peak area over two spectral bands 300–345 nm + 435–480 nm, at an excitation of 254 nm.

Identifier
Source https://www.polardata.ca/pdcsearch/PDCSearchDOI.jsp?doi_id=12742
Metadata Access http://www.polardata.ca/oai/provider?verb=GetRecord&metadataPrefix=fgdc&identifier=12742_fgdc
Provenance
Creator Lafreniere, Melissa; Fouché, Julien; Lamoureux, Scott
Publisher Canadian Cryospheric Information Network
Contributor Polar Data Catalogue
Publication Year 2017
Rights Research programs, CCIN, or ArcticNet take no liability for the use or transmission of this data
OpenAccess true
Contact melissa.lafreniere(at)queensu.ca; pdc(at)uwaterloo.ca
Representation
Language English
Format Computer file
Discipline Biogeochemistry
Spatial Coverage (-109.500W, 74.900S, -109.500E, 74.900N)
Temporal Coverage Begin 2012-06-02T00:00:00Z
Temporal Coverage End 2012-08-02T00:00:00Z