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 Research
Issues:
Air Pollution Impacts on Aquatic Biota
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Air Pollution Impacts on Aquatic Biota:
Background:
Atmospherically deposited pollutants may pose a substantial risk to aquatic resources in Mount Rainier, North Cascades, and Olympic National Parks. Acidic deposition, excessive nitrogen loading from the atmosphere, and pesticides in rain and snow are prime examples of pollutants that can have negative impacts on aquatic ecosystems in national parks. Air pollution from nearby urban areas affects the air quality in these parks and may also be affecting park resources. Preliminary scientific evidence indicates that significant quantities of a wide variety of pollutants are carried across the Pacific Ocean from Asia to North America, sometimes in as few as four days. These pollutants may be affecting surface water quality and associated biota. Although precipitation chemistry is monitored at three National Atmospheric Deposition Program/National Trends Network stations in Western Washington, these sites are at low and mid elevations; little information is available about precipitation chemistry at high-elevation sites in the parks in Washington because of the difficulty of access. However, data from a bulk precipitation collector located at approximately 5000-ft. elevation on the south side of Mount Rainier National Park has shown elevated levels of sulfates and nitrates.
MORA, NOCA, and OLYM receive abundant precipitation, mostly in the form of snow, which accumulates during the winter in a deep seasonal snowpack. When the snowpack melts in the spring, large amounts of mildly acidic snowmelt are released quickly into the terrestrial and aquatic ecosystems. The terrestrial ecosystem provides little buffering capacity because soils are poorly developed and bedrock consists mostly of unreactive volcanic and granitic bedrock that weathers relatively slowly. Thus, snowmelt moves rapidly into lakes and streams with little modification. During the initial phase of snowmelt, high concentrations of solutes often are released, causing an "acid pulse" from the snowpack (Johannessen and Henriksen, 1978) Mid-winter melting or rain-on-snow precipitation events, which are common in the northern Cascade Mountains, can cause multiple acid pulse events that can adversely affect aquatic biota.
Glaciers provide abundant particulate matter which can act as a carrier of some pollutants. As reservoirs of snow from distant winters, it is also possible that glaciers contain atmospheric pollutants from decades ago. Unexpected pulses of pollutants may occur when glacial ice containing pollutants reach the glacier margin and melt. Stored pollutants could potentially significantly affect aquatic resources in the parks considering the volume of snow and ice in each park. North Cascades National Park Service Complex (NOCA) encompasses more than 300 glaciers and numerous perennial snowfields. Mount Rainier National Park (MORA) contains numerous perennial snowfields and 25 major glaciers covering 35 square miles and with an ice volume of 991 million square feet and 156 billion cubic feet. In Olympic National Park there are over 260 glaciers, 11 major watersheds, and over 400 lakes and wetlands.
Recent research in the Canadian Rockies and elsewhere indicates that biota in glacier-fed subalpine lakes contain high concentrations of organochlorines (OC) such as DDT and PCB. These reports are somewhat surprising, since these lakes are in high elevation, pristine environments that are far distant from direct sources of pollution. However, as in MORA, NOCA, and OLYM, the lakes studied at Banff National Park receive meltwater from glaciers and abundant winter snowfall. The scientists studying the Banff lakes predicted that source water for lakes fed by glaciers will have relatively high levels of OC pesticides for at least another century.
The presence of atmospherically deposited pollutants in snow, rain, and glaciers is a topic of increasing concern as scientists seek to explain declines in amphibian populations in remote areas of the United States. There is presently no information available to park managers on current or past levels of OC pollution of glaciers, lakes or aquatic biota. This knowledge gap is critical as we develop management programs to address impacts from fish-stocking, global change, and human recreation.
Park Focus:
Mount Rainier National Park
North Cascades National Park
Olympic National Park
Research Needs:
How do accumulations of OCs and other persistent organic pollutants and heavy metals in fish and/or amphibians vary with respect to watershed area, elevation, and snow and ice drainage?
What are the levels of pesticide concentrations in seasonal snowpacks along elevational gradients during the period of maximum accumulation?
How do the relative levels of pollutants differ between glacial-fed and non glacial-fed lakes?
Do pollutant levels vary along an east-west gradient that corresponds to a precipitation gradient?
Is there a relationship between contaminant burden in fish and/or amphibian tissues and those of organisms at lower trophic levels and lake bottom sediment?
Can these contaminant concentrations found in the top predators at each lake be related to other physiographic/biologic factors of the recipient watershed?
What atmospherically deposited pollutants are deposited in glaciers and snowpacks within the three parks? Do concentrations of these pollutants vary geographically?
Available Resources:
Chemistry of many lakes in North Cascades NP has been surveyed recently in support of a high lakes management plan.
Limnologic, paleolimnologic data is available for most lakes within MORA. Fish and amphibian surveys have also been conducted at many lakes and ponds.
A diatom calibration set is available for the Cascade Mountain Ecoregion. (Eilers, J.M., P.R. Sweets, D.F. Charles, K.B. Vache. 1998. E&S Environmental Chemistry, Inc. Corvallis, Oregon)
References Cited:
Johannessen, M., and Henriksen, A., 1978, Chemistry of snow meltwater: changes in concentration during melting: Water Resources Research, v. 14, no. 4, p. 615-619.
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