Return to search

The Provenance of, and Relationship Between, Methane and Halogens in Groundwater in Eastern Ontario

The geology, hydrogeology, and groundwater geochemistry are described for an interface aquifer in Eastern Ontario exhibiting anomalously high proportions of iodine (I) as iodide (I-) and dissolved methane (CH4). The studied area is unique in that it shows a significant marine influence, attributed to the most recent Champlain Sea incursion 10 – 12 ka BP, which has implications for I and CH4 enrichment. I and CH4 in groundwater are found in high proportions in reducing fossil seawaters, which are typically observed in depressions in the bedrock surface that are overlain by thick layers of glaciomarine muds. I is released via microbial decomposition of marine phytoplankton into mud porewaters, where it is then leached to underlying groundwaters. 129I and 14C isotopic signatures of I and C compounds highlight the importance of allochthonous I and C sources in the Champlain Sea basin derived from glacial abrasion of the surrounding terrain and imported via glacial meltwater. CH4 is microbial in origin, with marine phytoplankton from the Champlain Sea incursion and ancient terrestrial organic matter from an Early Wisconsinian interstadial period (60 – 75 ka BP) as the dominant substrates. A thermogenic CH4 component was observed for areas underlain by the Billings shale unit. Both I and CH4 originate at least partially from the same marine phytoplankton source within the muds, demonstrate similar controls on enrichment, and have a Spearman’s rank coefficient of 0.62, indicating that the correlation between I and CH4 in groundwater in the studied area is significant.

Identiferoai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/37912
Date24 July 2018
CreatorsLemieux, Alexander
ContributorsClark, Ian
PublisherUniversité d'Ottawa / University of Ottawa
Source SetsUniversité d’Ottawa
LanguageEnglish
Detected LanguageEnglish
TypeThesis
Formatapplication/pdf

Page generated in 0.0018 seconds