Comparison and contrast of lake sediment P composition between the Boreal Plains and Prairie ecozones

Photo by Cohen Berg on Unsplash

The Prairie provinces of Canada, which includes parts of Manitoba, Saskatchewan, and Alberta, are a vast region, which includes expansive agriculture in the Prairie ecozone, shifting to forests and forestry further north in the Boreal Plains ecozone. In the southern and mid-latitude parts of the provinces, water security challenges are common, including issues of poor water quality associated with nutrient-rich lakes that are subject to recurrent cyanobacterial blooms.

Our work explores the variation in lakes within the region, using broad-scale sampling of lakes to assess whether landscape classifications can help understand variation within lakes, and specifically to understand how lake sediments differ in ways that may influence water quality. Landscape classifications were helpful in understanding variation in nutrients, pH, and salinity (including sulfate, an important constituent of salinity in the region). A key feature of the region is its soils (and associated variation in land use), which have overarching impacts on lakes.

Read this open access paper on the FACETS website.

Prairie ecozone watersheds are more dominated by agricultural activities and chernozemic soils (a grassland soil type with high pH and high calcium and organic matter concentrations) and are associated with higher concentrations of calcium-bound P in lake sediments. In contrast, Boreal Plains watersheds have higher levels of organic and residual P in lake sediments associated with dominance of Luvisolic soils (a forest soil type with high pH and high calcium derived from sedimentary rocks), and organic soils.

Characteristics of lake sediments are important to predicting the role of sediments in supplying nutrients to the water column — which can sustain cyanobacterial blooms. Interestingly, porewater P concentrations, which are an indicator of the potential for P release did not differ between the two ecozones, but other factors, including soil type, land use, and lake pH were helpful predictors of porewater P.

This region is tremendously variable region in terms of its lakes and their water quality. Here, we see the overarching importance of soils and associated land uses in explaining variation in water quality and lake sediments.

Read the paper — **Lake sediment phosphorus and relationships to soils and chemistry across the Boreal Plains and Prairie ecozones *by Mauro B. de Toledo and Helen M. Baulch in FACETS*.