The Peatland pH Project

Welcome! This video introduces our science fair project, The Peatland pH Project, by Alexander Crossgrove and Maria Luisa Dos Santos.

We chose this project because we are interested in the environmental history of Sudbury and how mining has affected our city. We were inspired by our Grade 9 science teacher, Sylvia Donato, as well as a field trip to the Laurentian peatlands, where we observed areas that appeared damaged or “dead.” Learning that Sudbury was once described as a barren, lunar-like landscape made us wonder if soil acidity played a role in this environmental damage.

Our main question was how soil pH changes at different depths in peat cores and whether it differs between Sudbury and a less impacted site, Nairn Centre. Based on this, we hypothesized that deeper layers would have higher pH (less acidic) because they formed before major mining activity, and that the Sudbury core would show more variation. We also expected the Sudbury core to have a higher density than the Nairn Centre core due to environmental differences.

This project is important because peatlands play a major role in the global climate. Although they cover only about 3% of Earth’s surface, they store nearly one-third of the world’s carbon. When peatlands are damaged, they release carbon dioxide, contributing to climate change. However, healthy peatlands, absorb carbon, reduce wildfire risk by holding water, and support biodiversity.

By studying how mining has impacted peatlands, our project highlights the importance of protecting and restoring these ecosystems. Understanding these changes can help scientists and communities make better decisions to reduce environmental damage and support a more sustainable future.

To begin our project, we conducted background research using reliable sources such as university websites and government reports about peatlands and mining in Sudbury. We also spoke with experts like Dr. Gerard Courtin and Dr. Peter Beckett, who helped us understand peatland ecosystems and how pollution may have affected them over time.

Dividing The Core

We collected peat core samples from two locations: the Lake Laurentian Conservation Area in Sudbury and a peatland near Nairn Centre. Each core was divided into 5 cm sections, which represent different time periods (newer layers at the top and older layers deeper down). This allowed us to study how conditions changed over time.

Testing Acidity (pH) Levels

To measure pH, we took 3 g of soil from each section and mixed it with 30 mL of distilled water in labeled test tubes. The samples were sealed, shaken, and left overnight to settle. A calibrated pH meter was then used to measure each sample after 3 minutes. We repeated this process three times at each depth to improve accuracy, resulting in a total of 144 pH tests.

Testing Density

To measure density, we collected samples from each depth using a corer. We recorded the wet mass and size of each sample, then dried them in an incubator for three days to remove all water. After drying, the samples were weighed again to calculate dry mass and determine both wet and dry density. In total, 48 density samples were tested except in sections where there was not enough material to do so.

Controls

To ensure fair results, we controlled variables by using distilled water (pH 7), calibrating the pH meter with buffer solutions, and keeping samples sealed and frozen when not in use. This helped reduce errors and improve the reliability of our data.

pH Results

The pH results show clear patterns when graphed across depth. A line (or dotted line) graph is especially useful here because it helps show how values change over a continuous range. In peat cores, depth represents time with the surface layers being the most recent, while deeper layers are older. Because of this, the graph allows us to visually track how soil acidity has changed over time.

In the Laurentian core, pH values range from 4.61 to 5.83, with the lowest (most acidic) values occurring between 30-50 cm. This section forms a noticeable dip on the graph, making the trend easy to identify. Above and below this range, pH values increase, especially in deeper layers, which suggests less acidic conditions further back in time. The gradual slope of the line helps show this long-term trend clearly.

The Nairn Centre core shows a much flatter and more consistent line, meaning there is less change in pH over time. Aside from a small spike at 15-20 cm, the values remain steady, indicating more stable environmental conditions.

Density Results

The density graphs also benefit from a line format, as they show how density changes gradually with depth. In the Laurentian core, wet density ranges from 0.10 to 0.20 g/cm³, while dry density ranges from 0.01 to 0.04 g/cm³. The graph shows peaks in the mid-depth layers (around 50-80 cm), where both wet and dry densities increase.

In the Nairn Centre core, density values are generally lower and more variable. Wet density ranges from 0.05 to 0.18 g/cm³, and dry density ranges from 0.005 to 0.02 g/cm³. A dip in density around 60-70 cm is clearly visible on the graph, followed by an increase at deeper levels.

Summary of Patterns

Overall, using line graphs makes it easier to see that both pH and density change over depth (and therefore over time). The Laurentian core shows more noticeable changes and trends, while the Nairn Centre core remains more stable. These visual patterns help highlight how environmental conditions have shifted throughout the history recorded in the peat layers.

Figure 1. pH levels at different depths in the Laurentian peat core

Figure 2. pH levels at different depths in the Nairn Centre peat core

Figure 3. Comparison of wet and dry density across depths in the Laurentian peat core

Figure 4. Comparison of wet and dry density across depths in the Nairn Centre peat core

Figure 5. Comparison of dry density between the Laurentian and Nairn Centre peat cores across depth enlarged

Our results show that soil pH generally increases with depth, meaning deeper layers are less acidic and represent earlier time periods. In the Laurentian core from Sudbury, the most acidic section occurs between 30-50 cm, likely reflecting the time when mining pollution was most intense. This supports our hypothesis that mining increased soil acidity. Deeper layers show higher pH values, suggesting conditions before major industrial activity.

pH Analysis

A noticeable increase in pH at 15-25 cm in the Laurentian core is likely due to aerial liming, which was used in the Sudbury area to reduce soil acidity during regreening. Since liming occurred around Laurentian but not at Nairn Centre, this explains the clear spike in the Laurentian data. The small spike in the Nairn Centre core at a similar depth is most likely an outlier, as there is no known environmental cause for it. Overall, the Nairn Centre core shows a more stable pH, indicating less human impact.

Density Analysis

The density results also support our predictions. Wet density was consistently higher than dry density, showing that peat holds a large amount of water. The Laurentian core generally had higher dry density than the Nairn Centre core, suggesting it is more compact or contains more mineral material. Density also varied with depth, especially in the middle layers, reflecting changes in how the peat formed over time.

Overall, our results show that human activity has had lasting effects on soil and peatland environments.

If we were to improve this project, we would collect new core samples with no missing sections, especially from the Laurentian site, so that every depth could be tested equally. We would also gather more material to allow multiple trials for density, improving accuracy and reliability.

As a next step, we would collect additional cores from Sudbury, including areas like Copper Cliff where mining activity is still present. This would allow better comparison between heavily impacted and less impacted sites.

In the future, this research could also help explore ways to restore peatlands and reduce long-term environmental impacts of mining.

We would like to sincerely thank everyone who contributed to the success of our project. We are especially grateful to Dr. Gerard Courtin for helping us understand the environmental history of Sudbury and the impacts of mining in the area. We also appreciate his communication with Dr. Graeme Spiers, who provided guidance on appropriate ratios for our pH testing. We thank Dr. Peter Beckett for assisting with fieldwork and helping us collect core samples.

We are grateful to Ms. Potvin for providing access to laboratory equipment and resources, and to Mr. Dykstra for his guidance and support throughout the project.

Finally, we would like to give a heartfelt thank you to Ms. Donato. She played a major role in supporting our learning and growth over the past two years. We are deeply saddened by her passing and dedicate this project to her memory.

Information Sources:

Earth Sciences Museum. (n.d.). The mining history of the Sudbury area. University of Waterloo. https://uwaterloo.ca/earth-sciences-museum/educational-resources/mining/mining-history-sudbury-area

Cornell University Nutrient Management Spear Program. (n.d.). Agronomy fact sheet 106. Cornell University. https://nmsp.cals.cornell.edu/publications/factsheets/factsheet106.pdf

SPC Nickel Corp. (2022, June 13). SPC Nickel intersects 24 metres of 0.97% nickel equivalent at the Lockerby East nickel-copper project, Sudbury, Ontario. https://spcnickel.com/site/assets/files/5664/spc_nickel_june_13_j_2022_lke_final.pdf

Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry. (2021, December 13). Geotours discovery site: Mining camp. Government of Ontario. https://files.ontario.ca/ndmnrf-geotours-discovery-site-mining-camp-en-2021-12-13.pdf

Natural Resources Canada. (2025, January 31). Nickel facts. Government of Canada. https://natural-resources.canada.ca/minerals-mining/mining-data-statistics-and-analysis/minerals-metals-facts/nickel-facts/20519

Laurentian University. (n.d.). COP15: Greater Sudbury’s regreening success. https://laurentian.ca/about/office-of-sustainability/cop15

Glencore Canada. (n.d.). Smelting and recycling. https://www.glencore.ca/en/sudburyino/what-we-do/smelting-and-recycling

World Economic Forum. (2025, February 21). Peatlands store twice as much carbon as forests – here’s what we can do to save them. https://www.weforum.org/stories/2025/02/peatlands-store-carbon-climate-change/

Laurentian University. (2023). Past, present, and future of Lake Laurentian and its watershed. https://laurentian.ca/assets/files/Past%20Present%20and%20Future%20of%20Lake%20Laurentian%20and%20its%20Watershed-compressed.pdf

Google Earth. (n.d.). Satellite imagery of Sudbury, Ontario, Canada [Map]. Google. https://earth.google.com/web/@46.49349223,-81.25857667,279.27837619a,145441.25903981d,35y,0h,0t,0r/data=CgRCAggBMikKJwolCiExZWsycUpHUkJoMV9XMldOb0VhMUY3Ul84U1p6S2FoMXIgAToDCgEwQgIIAEoICNSunqEDEAE?authuser=0

Clarke, T. (2024, May 2). Sudbury moves to protect 30% of its lands and lakes. Elliot Lake Today. https://www.elliotlaketoday.com/local-news/sudbury-moves-to-protect-30-of-its-lands-and-lakes-8686028

The Canadian Encyclopedia. (n.d.). Greater Sudbury. https://thecanadianencyclopedia.ca/en/article/sudbury-greater

Sudbury.com. (2021, July 28). Moonscape to greenscape: A pic of your favourite tree can win you a prize. https://www.sudbury.com/local-news/moonscape-to-greenscape-a-pic-of-your-favourite-tree-can-win-you-a-prize-3940708

People (Consulted):

Donato, S.

Courtin, G.

Beckett, P.

Dykstra, M.

Potvin, V.