The effects of human activities and extreme meteorological events on sediment nitrogen dynamics in an urban estuary,Escambia Bay,Florida, USA |
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Authors: | Kristin A Smith Jane M Caffrey |
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Institution: | (1) Science Applications International Corporation (SAIC), 1140 Eglin Parkway, Shalimar, FL 32579, USA;(2) University of West Florida, 11000 University Parkway, Pensacola, FL 32514, USA |
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Abstract: | This study examined how sediment-sorbed PCBs and several large storms affected sediment nutrient dynamics based on potential
nitrification rates and benthic flux measurements. PCBs were hypothesized to negatively affect potential nitrification rates
due to the sensitivity of nitrifying bacteria. Sediment disturbance caused by the succession of storms, which can enhance
nutrient inputs and phytoplankton production, was hypothesized to enhance both potential nitrification rates and benthic flux
measurements as a result of higher nutrient and organic matter concentrations. Potential nitrification rates, benthic fluxes
(NO3
− + NO2
−, NH4
+, and DIP), sediment PCB content, water content, organic content, salinity, bottom water dissolved oxygen, and sediment chlorophyll
were measured at 13 different sites in Escambia Bay during the summer of 2005. Potential nitrification rates were highest
at deep, organic-rich sites. Total PCB content did not have a direct effect on potential nitrification rates. An analysis
of recent changes in benthic processes in relation to extreme meteorological events was performed by comparing the 2005 results
with data from 2000, 2003, and 2004. Storm effects on sediment biogeochemistry were mixed with sediment nitrogen dynamics
enhanced at some sites but not others. In addition, SOC and NH4
+ fluxes increased in deeper channel sites after Hurricanes Ivan and Dennis, which could be attributed to the deposition of
phytoplankton blooms. Sediment nutrient dynamics in Escambia Bay appear to be resilient to these extreme meteorological events
since there were no significant effects on sediment processes in the Bay as a whole.
Handling editor: P. Viaroli |
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Keywords: | Nitrification Benthic flux Nutrients Estuary PCB Nitrogen |
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