Premium
Passive sampling method for high‐resolution concentration and isotopic composition of dissolved methane in A rctic lakes
Author(s) -
Goldman Amy E.,
Cadieux Sarah B.,
White Jeffrey R.,
Pratt Lisa M.
Publication year - 2016
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.1002/lom3.10070
Subject(s) - sampling (signal processing) , water column , methane , dissolved organic carbon , chemistry , protein data bank (rcsb pdb) , flux (metallurgy) , analytical chemistry (journal) , environmental science , environmental chemistry , hydrology (agriculture) , geology , oceanography , physics , stereochemistry , geotechnical engineering , organic chemistry , detector , optics
Lakes are important sources of methane (CH 4 ), accounting for 6–16% of natural global CH 4 emissions annually. Vertical spatial resolution of CH 4 sampling in the water column of lakes is limited because of physical dimensions of sampling devices and sampling‐induced mixing. To improve pool‐size estimates of carbon, diffusive flux calculations for CH 4 , and detailed mechanistic understanding of CH 4 dynamics in lakes, more precise vertical profiles of dissolved gases through the water column are vital. We investigate the use of commercially available passive diffusion bags (PDBs) to obtain highly resolved (0.5‐m increments) vertical profiles of dissolved CH 4 concentrations and isotopic composition ( δ 13CCH 4). Laboratory experiments determined PDB equilibration time was between 5 d and 9 d for both CH 4 concentration and δ 13CCH 4. During July 2013, PDBs were deployed at intervals of 0.5‐m depth for 5 d in two lakes located < 5 km from the southwestern margin of the Greenland ice cap. Data from PDB samples were compared with samples collected using a submersible, electric pump. In both lakes, PDB and pump samples yielded vertical profiles for CH 4 concentration and δ 13CCH 4that were in close agreement (CH 4 concentration R 2 = 0.998, p < 0.001; δ 13CCH 4R 2 = 0.970, p < 0.001). Overall agreement between PDB and pump samples verifies the applicability of the PDB approach to dissolved CH 4 sampling. High‐vertical resolution sampling of dissolved gas concentrations and isotopic composition using PDBs can provide more accurate estimates of pool sizes and diffusive fluxes that advance understanding of production, consumption, and emission processes controlling trace gas dynamics in lacustrine environments under warming climate.