{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/44829"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/44829","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Pesticide distribution in water, sediment, and fish of the Occoquan Watershed","abstract":"About 50 synthetic organic chemicals (SOCs), including pesticides and polyaromatic hydrocarbons (PAHs), have been identified as possible contaminants in the Occoquan Watershed. Since 1982, water, sediment, and fish samples have been collected from the streams and reservoirs of the watershed 2-4 times per year. The Occoquan Watershed Monitoring Laboratory (OWML) collected samples and analyzed for a targeted set of compounds. Beginning in 1993, new SOC screening methods consisting of solid-phase extraction (SPE) followed by gas chromatography with mass spectrometric detection (GC/MS) were developed for water and sediment samples. A similar method for fish tissue was developed in this study using methanol extraction with C-18 and alumina SPE cleanup. Method detection limits (MDLs) ranged from 0.03-0.37 mg/kg wet weight and recoveries in matrix spikes ranged from 15-92%. Very few SOCs in OWML's database were found at levels above method detection limits. In water, atrazine was the most commonly detected compound (87 detections out of 610 samples analyzed). It was also found in 8 sediment samples and 1 fish organ sample. Atrazine concentrations were highest in the spring; summer provided the most frequent detections. Detections occurred at multiple locations during the same sampling period; stations furthest west (nearest to agricultural areas) tended to show the highest values. Rainfall events were associated with 23% of atrazine detections. The raw and finished water samples from the two water treatment plants in the basin showed that the average atrazine removal by conventional treatment was 37%.","abstract_html":"About 50 synthetic organic chemicals (SOCs), including pesticides and polyaromatic hydrocarbons (PAHs), have been identified as possible contaminants in the Occoquan Watershed. Since 1982, water, sediment, and fish samples have been collected from the streams and reservoirs of the watershed 2-4 times per year. The Occoquan Watershed Monitoring Laboratory (OWML) collected samples and analyzed for a targeted set of compounds. Beginning in 1993, new SOC screening methods consisting of solid-phase extraction (SPE) followed by gas chromatography with mass spectrometric detection (GC/MS) were developed for water and sediment samples. A similar method for fish tissue was developed in this study using methanol extraction with C-18 and alumina SPE cleanup. Method detection limits (MDLs) ranged from 0.03-0.37 mg/kg wet weight and recoveries in matrix spikes ranged from 15-92%. Very few SOCs in OWML's database were found at levels above method detection limits. In water, atrazine was the most commonly detected compound (87 detections out of 610 samples analyzed). It was also found in 8 sediment samples and 1 fish organ sample. Atrazine concentrations were highest in the spring; summer provided the most frequent detections. Detections occurred at multiple locations during the same sampling period; stations furthest west (nearest to agricultural areas) tended to show the highest values. Rainfall events were associated with 23% of atrazine detections. The raw and finished water samples from the two water treatment plants in the basin showed that the average atrazine removal by conventional treatment was 37%.","abstract_has_math":false,"creators":["Hall, Ellen L."],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Environmental Planning","degree_department":"Environmental Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Dietrich, Andrea M."],"committee_members":["Godrej, Adil N.","Grizzard, Thomas J."],"year":1996,"date_issued":"1996-04-25","date_published":"1996-04-25","updated_at":"2026-07-22T22:19:59Z","subjects":["pesticides","monitoring"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-09182008-063530"],"render_values":[{"text":"etd-09182008-063530","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/44829","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Dietrich, Andrea M."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Godrej, Adil N.","Grizzard, Thomas J."]},{"key":"dc:contributor.department","label":"Department","values":["Environmental Engineering"]},{"key":"dc:creator","label":"Author","values":["Hall, Ellen L."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T21:46:03Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T21:46:03Z","2008-09-18"]},{"key":"dc:date.issued","label":"Date","values":["1996-04-25"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Environmental Planning"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["pesticides","monitoring"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-09182008-063530"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/44829"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["About 50 synthetic organic chemicals (SOCs), including pesticides and polyaromatic hydrocarbons (PAHs), have been identified as possible contaminants in the Occoquan Watershed. Since 1982, water, sediment, and fish samples have been collected from the streams and reservoirs of the watershed 2-4 times per year. The Occoquan Watershed Monitoring Laboratory (OWML) collected samples and analyzed for a targeted set of compounds. Beginning in 1993, new SOC screening methods consisting of solid-phase extraction (SPE) followed by gas chromatography with mass spectrometric detection (GC/MS) were developed for water and sediment samples. A similar method for fish tissue was developed in this study using methanol extraction with C-18 and alumina SPE cleanup. Method detection limits (MDLs) ranged from 0.03-0.37 mg/kg wet weight and recoveries in matrix spikes ranged from 15-92%. Very few SOCs in OWML's database were found at levels above method detection limits. In water, atrazine was the most commonly detected compound (87 detections out of 610 samples analyzed). It was also found in 8 sediment samples and 1 fish organ sample. Atrazine concentrations were highest in the spring; summer provided the most frequent detections. Detections occurred at multiple locations during the same sampling period; stations furthest west (nearest to agricultural areas) tended to show the highest values. Rainfall events were associated with 23% of atrazine detections. The raw and finished water samples from the two water treatment plants in the basin showed that the average atrazine removal by conventional treatment was 37%."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Pesticide distribution in water, sediment, and fish of the Occoquan Watershed"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Dietrich, Andrea M."],"dc:contributor.committeemember":["Godrej, Adil N.","Grizzard, Thomas J."],"dc:contributor.department":["Environmental Engineering"],"dc:creator":["Hall, Ellen L."],"dc:date.accessioned":["2014-03-14T21:46:03Z"],"dc:date.available":["2014-03-14T21:46:03Z","2008-09-18"],"dc:date.issued":["1996-04-25"],"dc:description.abstract":["About 50 synthetic organic chemicals (SOCs), including pesticides and polyaromatic hydrocarbons (PAHs), have been identified as possible contaminants in the Occoquan Watershed. 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Atrazine concentrations were highest in the spring; summer provided the most frequent detections. Detections occurred at multiple locations during the same sampling period; stations furthest west (nearest to agricultural areas) tended to show the highest values. Rainfall events were associated with 23% of atrazine detections. 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