The hydrochemistry of high-elevation lakes in the Georgia Basin, British Columbia

Abstract

High-elevation lakes are sensitive to acidification from atmospheric deposition owing to their generally small catchment areas, thin soils and low bedrock weathering rates. The Georgia Basin, southwest British Columbia, Canada, receives atmospheric inputs from emissions originating in Vancouver, Victoria, and from marine traffic in the Strait of Georgia. There is growing concern on the influence of this air pollution on high-elevation systems in the region. Water chemistry and catchment characteristics were used to assess the sensitivity of 72 lakes in the Georgia Basin to acidic deposition. Twenty percent of the study lakes had pH levels less than 6, and acid neutralising capacity (ANC) concentrations below 20 μeq L–1, which are key thresholds for biological sustainability. Base cation and trace metal concentrations were low, typical of the dilute nature of high-elevation lakes (median conductivity = 7.0 μS cm–1). Nonetheless, concentrations of trace metals (such as lead) decreased with distance from major cities. The primary factors influencing the pH and ANC of surface waters were investigated using multiple linear regression; both ANC and pH were related to longitude and the proportion of the catchment dominated by ice and glaciers. Increasing sulphur deposition resulted in decreasing pH. The median critical load of acidity (sulphur) for the study lakes was approximately 70 meq m–2 y–1; 18% of the lakes received sulphur deposition (range: 6-81 meq m–2 y–1 for the period 2005-2006) in excess of their critical load

Hydrochemistry of Lake Rara: A high mountain lake in western Nepal

“…However, an increase in the concentration of ions such as PO 4 3− and NO 3 − can lead to eutrophication (Istvánovics, ; Wetzel, ). Similar to that, an increase in SO 4 2− can lead to acidification of water bodies (Strang, Aherene, & Shaw, ). These phenomena in turn affect the biogeochemical cycling of minerals and nutrients, thereby compromising aquatic ecosystem functions (Smith, Tilman, & Nekola, ).…”

Chronic low pH exposure affects the seawater readiness of juvenile Pacific sockeye salmon

“…This is of great concern in the region as it may lead to further acidification of fish-bearing waterways including lakes and streams. A recent study found that lakes in the Georgia Basin are at particular risk of acidification due to poor acid neutralizing capacity, high precipitation rates, and acid deposition from both local and long distance sources, and in fact, approximately 20% of these high-elevation lakes already have a pH of\6.0 (Strang et al 2010), which is lower than the pH of [6.5 recommended in guidelines from the Canadian Council of Ministers of the Environment (CCME), United States Environmental Protection Agency (US EPA), and British Columbia Ministry of Environment (BC MOE) for the protection of aquatic life (McKean and Nagpal 1991).…”

Potential Influence of Climate Change on the Acid-Sensitivity of High-Elevation Lakes in the Georgia Basin, British Columbia

“…Few studies have focused on the high-elevation lakes and catchments that scatter this region. One recent study [12], however, indicated that these lakes ( = 72) are sensitive to acidification and that 18% currently receive sulphur (S) deposition in excess of their critical load of acidification (CL(A)). The study also suggested that precipitation and the cover of glacier and ice significantly influenced the pH and acid neutralizing capacity (ANC) of these lakes.…”

“…The objective of this study, therefore, was to evaluate which chemical components of these ecosystems are significantly influenced by temperature and precipitation and how climate change may influence the acid-sensitivity of these highelevation catchments. Potential changes in lake chemistry, according to biogeoclimatic zone, were assessed based on a recent survey of high-elevation lakes [12]. In addition, weathering rates under increased temperature were estimated for a subset of catchments using the PROFILE model [15].…”