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| Title | Determination of PBT Chemical Trends in Selected Washington Lakes Using Age-Dated Sediment Cores, 2008 Sampling Results | |||
| Month-Year Published | June 2009 | |||
| Online Availability |
590 kilobytes, requires version 4.0 or later of Adobe Acrobat Reader Software get Acrobat Reader
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| Short Description |
Sediment cores were collected from Lake Washington, Lacamas Lake, and Offutt Lake as part of a long-term study evaluating contaminant trends across the state. Contaminant analyses for the 2008 sampling period included mercury, lead, and polycyclic aromatic hydrocarbons (PAHs). Overlying contaminant trends for each core varied by lake and analyte. Lake Washington has received higher contaminant loads than Lacamas Lake or Offutt Lake. However, concentrations of mercury and lead at all three lakes were found within expected concentrations based on previous Washington State sediment core studies. (Also see abstract below) | |||
| Publication Number | 09-03-030 | |||
| Author(s) | Furl, C., C. Meredith, and M. Friese | |||
| Print Availability | ||||
| Number of pages | 34 + app (57 total) | |||
| Keywords | chemical, Clark County, contaminant, lake, lead, sampling, sediment, Thurston, trend | |||
| Subject Waterbodies |
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| Related Publications | Title | Relationship | ||
| Quality Assurance Project Plan: Depositional History of Mercury in Selected Washington Lakes Determined from Sediment Cores. | supporting publication | |||
| Addendum #1 to Quality Assurance Project Plan: Depositional History of Mercury in Selected Washington Lakes Determined from Sediment Cores. | supporting publication | |||
| History of Mercury in Selected Washington Lakes Determined from Age-Dated Sediment Cores: 2006 Sampling Results | part of a series | |||
| History of Mercury in Selected Washington Lakes Determined from Age-Dated Sediment Cores: 2007 Sampling Results | part of a series | |||
| Abstract | Long Description |
This report presents results from the third year of a study to evaluate contaminant trends in lakes using age-dated sediment cores. During August 2008, the Washington State Department of Ecology (Ecology) collected deep sediment cores from Lake Washington (King County), Lacamas Lake (Clark County), and Offutt Lake (Thurston County). Ecology analyzed sediment horizons for mercury, lead, and polycyclic aromatic hydrocarbons (PAHs). Dates were applied to each sediment horizon based on 210Pb measurements. Lake Washington sediments received substantial contaminant loading over the first half of the 1900s. Concentrations of mercury and lead declined significantly after peaking in the 1950s and 1970s, respectively. PAH concentrations display an erratic pattern since the 1960s. The most recent sediment intervals show a declining trend in PAH concentrations. Organic carbon-normalized PAH concentrations were 10 - 45 times higher in Lake Washington than in Offutt and Lacamas Lakes since the 1970s. Trends at Lacamas Lake displayed overall decreases for all three contaminants during the 1900s. The observed trend appears to be closely tied to increasing sedimentation rates in the lake. The uppermost sediment horizon had the lowest contaminant concentrations for all three analytes when compared to the other study lakes. Offutt Lake sediments displayed an increasing trend in lead and mercury after the 1850s. Concentrations reached their maximum during the 1970s where they remain through recent sediments. PAH concentrations were low at the lake and had little variation when compared to the other two study lakes. The highest total PAH concentration was found near the top of the sediment core. |
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This page last updated June 12, 2009
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