Potential Effects of Contaminants on Fraser River Sockeye Salmon

with clear-cut logging. Such releases <strong>of</strong> fine sediment can result in elevated levels <strong>of</strong> TSSin water and/or degradation <strong>of</strong> the quality <strong>of</strong> stream-bed substrates (Newcombe andMacDonald 1991; Caux et al. 1997). However, forest management activities can alsoresult in the losses <strong>of</strong> fertilizer and/or pesticides that are applied to enhance the production<strong>of</strong> timber (i.e., through run<strong>of</strong>f to receiving waters). Some <strong>of</strong> the pesticides that are usedto manage forest resources in the study area include (Verrin et al. 2004):• Herbicides, such as glyphosate (which accounts for over 90% <strong>of</strong> forestpesticide herbicide use), triclopyr (which has increased in use between 1991and 1998, and has been correlated with pre-spawn mortality in late-runsockeye salmon; Johannessen and Ross 2002), picloram, and2,4,-dichlorophenoxyacetic acid (2,4-D); and,• Insecticides, such as BT, fenithrothion, carbaryl, and monosodiummethanearsonate (MSMA).In addition, to nutrients, TSS, and pesticides, run<strong>of</strong>f from forest management areas has thepotential to contain a variety <strong>of</strong> fire-suppression and fire-retardant chemicals. There are avariety <strong>of</strong> fire-suppression chemicals on the market (e.g., AnsulSilv-Ex, Angus ForExpanS, Fire Quench, 3M Firebreak, and Phos-ChekWD-881; Adams and Simons 1999). Theseproducts are all foams, containing surfactants, foaming agents, and wetting agents. Theywork by increasing the ability <strong>of</strong> water to penetrate fuels and, thereby, decreasing theirpotential to ignite. These products also insulate the fuel from heat and reduce contactwith the air. The surfactants contained in these products make them toxic to aquaticorganisms at concentrations in the 10 to 100 mg/L range (Gaikowski et al. 1996; Mizukiet al. 2007)Long-term fire retardants, such as Phos-Chek D75-F, Phos-Chek D75-R, Fire-Trol GTS-R, and FireTrol 931, typically contain mixtures <strong>of</strong> diammonium sulphate, diammoniumphosphate, ammonium sulphate, ammonium phosphate, and/or ammonium polyphosphateas the active fire retardants (Adams and Simons 1999). These products also contain gumthickeners, an iron oxide-based colouring agent, and preservatives, which are mixed withwater to ensure uniform dispersal. The active ingredients react with the products <strong>of</strong>combustion to lower the combustibility <strong>of</strong> the fuel (Johannnessen and Ross 2002). Thetoxicity <strong>of</strong> fire-retardant chemicals is primarily due to the formation <strong>of</strong> ammonia and aretoxic to aquatic organisms at concentrations in the 100 to 1000 mg/L range (Gaikowski etal. 1996; McDonald et al. 1997). However, the presence <strong>of</strong> other ingredients, such assodium ferrocyanide, can render these products more toxic, primarily because photolysiscan lead to the formation <strong>of</strong> cyanide (which is highly toxic to fish; Little and Calfee 2000).35