Acidification at Plastic Lake, Ontario: Has 20 Years Made a Difference?

Abstract

In response to reduced sulphur emissions, there has been a large decrease in sulphate (SO 2À 4 ; −0.97 μeq l −1 year −1 ) and hydrogen (−1.18 μeq l −1 year −1 ) ion concentration in bulk precipitation between 1980 and 2000 at Plastic Lake in central Ontario. The benefit of this large reduction in SO 2À 4 deposition on stream water chemistry was assessed using the gauged outflow from a conifer-forested catchment (PC1; 23.3 ha), which is influenced by a small wetland located immediately upstream of the outflow. Sulphate concentrations declined, but not significantly due to large inter-annual variation in SO 2À 4 concentration. Between 1980 and 2000, there were significant increases in dissolved organic carbon, ammonium and potassium concentration likely reflecting increased mineralisation in the wetland. Calcium concentrations in PC1 decreased during the two decade period (−2.24 μeq l −1 year −1 ), as a consequence there was no improvement in stream pH and the Ca:Al ratio in PC1 continued to decline. A similar response was noted in an upland-draining subcatchment of PC1-08 that has been monitored since 1987. Despite large reductions in SO 2À 4 deposition and almost complete retention of nitrogen in soil, there has been no improvement (in terms of pH) in stream water at PC1 due to a combination of soil acidification and climatic (droughts, increased mineralisation) perturbations.

Cladocera assemblages from the surface sediments of south-central Ontario (Canada) lakes and their relationships to measured environmental variables

“…Skjelkvale et al, 2005), recovery from acid deposition has been delayed in many Ontario lakes due to lower inherent buffering capacities (e.g. Stoddard et al;1999;Watmough et al, 2007). Chemical changes over decades, coupled with variation in the buffering capacity among lakes, have resulted in a strong gradient of acidity and ion concentrations among lakes in the landscape.…”

Importance of rainfall partitioning in a northern mixed forest canopy for soil water isotopic signatures in ecohydrological studies

“…The study was conducted in the Plastic‐1 (PC‐1, 23.3 ha) subcatchment of Plastic Lake (Figure ) on the southern border of the Canadian Shield near Dorset, Ontario, Canada (45°11′N, 78°50′W). Pleistocene glacial till overlies Precambrian metamorphic silicate bedrock (Wels, Cornett, & LaZerte, ), and the thin soil cover is formed from sandy basal tills with an average depth of ~0.4 m to bedrock (Neary, Mistray, & Vanderstar, ; Watmough, Aherne, Eimers, & Dillon, ). Soils are overlain with an ~5‐cm‐thick LFH layer (Neary et al, ) and are sandy with minor clay and low organic matter contents showing little decline with depth (Buttle & House, ).…”

Assessing ecohydrological separation in a northern mixed forest biome using stable isotopes

“…1) on the southern edge of the Canadian Shield near Dorset, Ontario, Canada (45°11' N, 78°50' W). Pleistocene glacial till overlies Precambrian metamorphic silicate bedrock (Wels et al 1990), and thin soil cover is formed from sandy basal tills with an average depth of ~0.4 m to bedrock (Neary et al 1987, Watmough et al 2007. Visual observations of outcrops in PC-1 suggest the bedrock is relatively unfractured.…”