Aquatic Sciences Meeting, Albuquerque 2001

SS05 Groundwater at Aquatic Margins (Environmental Connections)

Date: Wednesday, February 14, 2001, Time: 2:15:00 PM

Location: Cimarron

McKenna, J, H, Williams College-Mystic Seaport, Mystic, USA, jmckenna@williams.edu

Nowicki, B, , University of Rhode Island, Narragansett, USA, bnowicki@gso.uri.edu

Gold, A, , University of Rhode Island, Kingston, USA, agold@uriacc.uri.edu

Requintina, E, , University of Rhode Island, Narragansett, USA, requintina@gso.uri.edu

Addy, K, , University of Rhode Island, Kingston, USA, kaddy@uriacc.uri.edu

PRELIMINARY STUDIES OF GROUNDWATER AT ESTUARINE MARGINS: DISSOLVED ORGANIC CARBON

Groundwater from a Rhode Island salt marsh was sampled to assess seasonal DOC dynamics and linkages to denitrification processes. Samples collected from 33 wells on March 2, 8, 15, May 18, and July 20, 2000 indicated a flush of DOC to groundwater following a spring thaw. On March 2, the marsh subsurface was frozen and DOC concentrations ranged from 0.3-41.3 mg/L (mean = 8.6 mg/L). By March 8, the marsh had thawed and DOC had increased significantly (range = 0.3-62.9 mg/L, mean = 31.3 mg/L). DOC increases from March 2 to March 8 were generally greater in shallower wells (35 cm) compared to deeper wells (200 cm) suggesting that DOC was delivered from the surface. By March 15, DOC had decreased (mean = 12.5 mg/L) and continued to decline through May (mean = 8.1 mg/L) and July (mean = 4.0 mg/L). It was hypothesized that denitrification would be stimulated by this availability of DOC. While high denitrification rates were indicated, initial analyses attempting to link groundwater DOC availability to denitrification suggested no direct relationship in these soils.

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Aquatic Sciences Meeting, Albuquerque 2001

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