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How do heavy metals, pesticides, and nutrients become stored in lake sediments?
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Lake Ann in North Cascades National Park, Washington, U.S., viewed from the park's Maple Loop Trail. The North Cascades National Park is a large wilderness area that preserves majestic mountain scenery, snowfields, glaciers, and other unique natural features.
Heavy metals, pesticides, and excessive nutrients are introduced into lake environments and ultimately stored in sediments primarily through two mechanisms: chemical precipitation and the settling of particulate matter.1
Once these materials reach the lake bottom, they become part of the sedimentary record. Within the uppermost layers of these sediments, large volumes of interstitial water often accumulate. This water can contain high concentrations of these stored constituents, which may subsequently be regenerated back into the lake water, potentially impacting the ecology of the system. Because these substances can be released back into the water column, they must be carefully accounted for when planning efforts to abate lake pollution.1