Holocene Carbon Accumulation & Paleohydrology in a Complex Wetland from Southern Ontario
Funded by NSERC & Lakehead University
In March of 2023 I was awarded an Undergraduate Student Research Award (USRA) through the National Science & Engineering Research Council (NSERC) of Canada. This competitive award provided me the opportunity to conduct research over the summer at Lakehead University under supervision of my mentor & supervisor, Dr. Florin Pendea. Our research aimed to investigate historic carbon accumulation and paleohydrology of a complex wetland in southern Ontario over the span of the Holocene. More specifically, we looked at past climatic patterns within a wetland at Langman Marsh over the past 10,000 years. This research provided information on the changes this wetland has endured and has potential to help predict future climatic trends in the region.
Last October a team of undergraduate students collected an 8-meter-long soil core from Langman Marsh. This is the core that a colleague and I spent the summer processing and analyzing. The age of the bottom of the core is still being determined, however a definitive date of about 10,000 yr BP halfway down the length of the core leads us to estimate that the age of the bottom is anywhere between 11,500 – 15,000 yr BP. Several analyses were done on this core including radiocarbon dating of organic material to get relative ages, the counting of microorganisms to give insight into past vegetation and hydrology, and the analysis of carbon and nitrogen to investigate climatic trends.
Major Trends
Late Glacial-Proglacial Complex
- Organic carbon and nitrogen accumulation was very low due to low primary productivity.
- Transitional period that saw an influx of shield meltwater void of bicarbonate, diluting local water and stopping carbon precipitation. Saw an increase in primary productivity in the Early Holocene due to warming of climate and decline in glaciers.
Late Glacial – Early Holocene
- Climatic warming during this transition drove a slight increase of both organic carbon and nitrogen, while inorganic carbon decreased. This event was likely caused by the development of cold oligotrophic pond conditions.
- After 11,400, organic content rapidly increases. The combination of high organic input and relatively low inorganic carbon, leads us to infer this was a high productivity pond with gyttja sediment (organic muck). This is what an oligotrophic pond should look like.
Hypsithermal (Mid-Holocene)
- This period was characterized by a surprising decrease of organic carbon and a major peak in inorganic carbon. This pattern is probably due to very warm pond water that favored carbonate precipitation, eutrophication, and development of abundant malacofauna (freshwater snails).
- During this period there was a spike in inorganic carbon. This is believed to have been caused by freshwater snails consuming and transforming organic carbon into inorganic carbon.
Late Holocene
- Climate cooling and progressive pond infilling resulted in a major ecological succession to a swamp environment defined by high organic sediment deposition (peat) and drastic decline in inorganic carbon deposition.
The takeaway from this research is that the hydrology and ecological succession in this complex wetland drove these long-term patterns of carbon accumulation.
See below for my scientific poster!
