Green Team members: Brittany Byrnes, Kayla MacDonald, Israel Mohammed and Elanor Dillabough
On August 9, 2018, the NAACAP Green Team visited four sites around Lundrigan’s Marsh to assess soil characteristics and water pH. The sites we visited included the hill just behind the parking lot of the Newfoundland Liquor Corporation (NLC) where our 2018 Green Team had previously planted trees, the lookout path overlooking Lundrigan’s Marsh, the northern margin of the Marsh, and the south eastern margin of the Marsh behind the PF Collins property. What we found painted a picture of a wetland with a recent history of human impact and change.
Soil texture at the NLC tree planting site and the lookout path were very similar; soils at both sites were composed of mostly course and fine gravel. The predominance of gravel found at these sites was due to infilling of gravel fill, and other human activities in the area. The pH of both of these sites was slightly acidic at a pH of around 6.0, which is very typical for Newfoundland soils.
However, the soil pH at the other two sites was far from typical. The Green Team observed that this was likely due to ongoing human impacts, which have been occurring over the history of industrial development and urbanisation around Lundrigan’s Marsh. The introduction of lime leachate from the substantial concrete deposits around the south and eastern portions of the Marsh may have altered the pH of the water and soil, making it a more alkaline environment. (Note since this soil sampling took place, NAACAP removed some of this concrete).
In the majority of Newfoundland’s wetlands, black spruce is a dominant tree species, and can often be seen fringing their perimeter, however the alteration of the pH of Lundrigan’s Marsh has changed its composition. This human impact has allowed Lundrigan’s Marsh to support different plant species uncommon in Newfoundland wetlands, including cattails, which are not as tolerant as black spruce to acidic environments.
The Green Team found that soils within the margins of the Marsh were mostly comprised of clay and silt, and was less likely to have been directly deposited there by human activities such as gravel infilling than the other sites. Because of the level of ongoing development around the Marsh, however, it is difficult to rule out the possibility that much of the silt and clay deposited in the Marsh may have arrived there as runoff from nearby land shaping activities. The leftover cement continues to maintain the unique alkaline environment at within the Marsh, where the Green Team found that the pH of the pond water was slightly alkaline at a pH of 7.5.
Newfoundland soil and surface water is naturally slightly acidic, in part due to the scarcity of naturally occurring limestone at the surface. Therefore, the pH of Lundrigan’s Marsh can vary. Water from the northern margin of Lundrigan’s Marsh, which is far away from the large concrete deposits, was found to be at a pH of 6.0.
The Green Team was astounded by the soil sampling results in the site to the left of the lookout behind the PF Collins property. Soil was collected from below an area that had naturally revegetated over the concrete that had been deposited into the Marsh. This soil was so basic that it reacted by bubbling vigorously when an acid was added to it. This vigorous reaction implied that the soil had an approximate pH of 9. The plants that were able to grow in this extreme alkaline environment were impressively tolerant of both the alkaline conditions as well as the physically demanding environment.
Our testing of soil characteristics around Lundrigan’s Marsh has revealed the ongoing human impact throughout its recent history from when Lundrigan’s Concrete Ltd was first established, to the modern ongoing development and expansion of the city.