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" Processes Affecting Agricultural Drainwater Quality and Organic Carbon Loads in California's Sacramento–San Joaquin Delta "
Deverel, Steven J.; Leighton, David A.; Finlay, Mark R.
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AL
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| Record Number
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926537
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LA8db266mg
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| Language of Document
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English
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| Main Entry
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Deverel, Steven J.; Leighton, David A.; Finlay, Mark R.
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| Title & Author
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Processes Affecting Agricultural Drainwater Quality and Organic Carbon Loads in California's Sacramento–San Joaquin Delta [Article]\ Deverel, Steven J.; Leighton, David A.; Finlay, Mark R.
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| Title of Periodical
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San Francisco Estuary and Watershed Science
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| Volume/ Issue Number
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5/2
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| Date
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2007
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| Abstract
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From 2000 to 2003 we quantified drain flow, drain-and ground-water chemistry and hydrogeologic conditions on Twitchell Island in the Sacramento-San Joaquin Delta. The primary objective was to quantify processes affecting organic carbon concentrations and loads in agricultural drainage water. We collected physical and chemical data in southern and northern areas: TN and TS, respectively. Corn grew in both areas during the spring and summer. The peat soils in the TN area are more decomposed than those in the TS area. Results elucidate processes affecting drain flow and concentrations under varying hydrologic conditions. During May through November, groundwater flows from the permanently saturated zone to drainage ditches, and the resulting average drainage-water quality and dissolved organic carbon (DOC) concentration was similar to the groundwater; the median DOC loads in the TN and TS study areas ranged from 9 to 27 g C/ha-day. The major ion chemistry and stable isotope data confirmed that groundwater was the primary source of drainflow. In contrast, during December through April the drainwater is supplied from the shallow, variably saturated soil-zone. The DOC concentrations, major-ion chemistry, and stable isotope data indicate that the shallow-zone water is partially evaporated and oxidized. Higher flows and DOC concentrations during these months result in higher median DOC loads, which ranged from 84 to 280 g C/ha-day.
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