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Denitrification dynamics in a newly ...

Poe, Amy C.

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Denitrification dynamics in a newly constructed wetland to treat agricultural runoff.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Denitrification dynamics in a newly constructed wetland to treat agricultural runoff./
Author:	Poe, Amy C.
Description:	124 p.
Notes:	Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1757.
Contained By:	Dissertation Abstracts International65-04B.
Subject:	Environmental Sciences. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3129791
ISBN:	0496770498

Denitrification dynamics in a newly constructed wetland to treat agricultural runoff.
Poe, Amy C.

Denitrification dynamics in a newly constructed wetland to treat agricultural runoff. - 124 p.

Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1757.

Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2004.

In 1999 a 5 ha tidal wetland was constructed on Open Grounds Farm (OGF) in eastern North Carolina in order to remove nutrients (N+P), sediment and pathogens in surface water draining from an 809 ha area of OGF. The farm is an 18,210 ha row crop farm located in the Neuse River Watershed. The wetland area is 5.1 ha with alternating sections of emergent marsh and open water. The design includes 19 wetland cells, each approximately 30 x 30 m, and adjacent ponds of equal size. The wetland cells were planted in the summer of 1999 with one of four native plant species including Spartina alterniflora, Spartina patens, Cladium jamaicense, and Juncus roemerianus . Nutrient loading and removal were determined from twice monthly nutrient collection at 24 sites within the wetland. Data from 1999--2002 show the constructed wetland is effective at the removal of inorganic nutrients, nitrate, ammonium and phosphate. Dissolved organic nitrogen removal occurred during the first two years of monitoring but was negative during the remaining time period. Loading following rainfall events (6 cm) accounted for 90% of dissolved inorganic nitrogen entering the wetland. Nitrogen removal via denitrification was measured monthly by analysis of dissolved N2, O2 and Ar in sediment incubation chambers with membrane inlet mass spectrometry. Experiments were conducted to assess the factors controlling denitrification rates in the constructed and a natural reference wetland. Data show the constructed wetland lags behind the natural one in many of the biogeochemical parameters (sediment carbon, Chl a, denitrification) used in measuring wetland function. Nitrate concentration appeared to be a key variable controlling denitrification rates in the constructed wetland. Spatial and temporal differences in denitrification were strongly affected by the overlying nitrate concentration in the constructed wetland. Denitrification accounted for less than 20% of total N removal for each year from 1999--2002. An annual N removal budget was calculated for microalgae, plant uptake and sediment N to determine their role in N removal in the constructed wetland. A long term data set is essential for assessing the time scales necessary for a created wetland to function as a natural system.

ISBN: 0496770498Subjects--Topical Terms:

676987
Environmental Sciences.

Denitrification dynamics in a newly constructed wetland to treat agricultural runoff.
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245 1 0 $a Denitrification dynamics in a newly constructed wetland to treat agricultural runoff.
300 $a 124 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1757.
500 $a Adviser: Hans W. Paerl.
502 $a Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2004.
520 $a In 1999 a 5 ha tidal wetland was constructed on Open Grounds Farm (OGF) in eastern North Carolina in order to remove nutrients (N+P), sediment and pathogens in surface water draining from an 809 ha area of OGF. The farm is an 18,210 ha row crop farm located in the Neuse River Watershed. The wetland area is 5.1 ha with alternating sections of emergent marsh and open water. The design includes 19 wetland cells, each approximately 30 x 30 m, and adjacent ponds of equal size. The wetland cells were planted in the summer of 1999 with one of four native plant species including Spartina alterniflora, Spartina patens, Cladium jamaicense, and Juncus roemerianus . Nutrient loading and removal were determined from twice monthly nutrient collection at 24 sites within the wetland. Data from 1999--2002 show the constructed wetland is effective at the removal of inorganic nutrients, nitrate, ammonium and phosphate. Dissolved organic nitrogen removal occurred during the first two years of monitoring but was negative during the remaining time period. Loading following rainfall events (6 cm) accounted for 90% of dissolved inorganic nitrogen entering the wetland. Nitrogen removal via denitrification was measured monthly by analysis of dissolved N2, O2 and Ar in sediment incubation chambers with membrane inlet mass spectrometry. Experiments were conducted to assess the factors controlling denitrification rates in the constructed and a natural reference wetland. Data show the constructed wetland lags behind the natural one in many of the biogeochemical parameters (sediment carbon, Chl a, denitrification) used in measuring wetland function. Nitrate concentration appeared to be a key variable controlling denitrification rates in the constructed wetland. Spatial and temporal differences in denitrification were strongly affected by the overlying nitrate concentration in the constructed wetland. Denitrification accounted for less than 20% of total N removal for each year from 1999--2002. An annual N removal budget was calculated for microalgae, plant uptake and sediment N to determine their role in N removal in the constructed wetland. A long term data set is essential for assessing the time scales necessary for a created wetland to function as a natural system.
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710 2 0 $a The University of North Carolina at Chapel Hill. $3 1017449
773 0 $t Dissertation Abstracts International $g 65-04B.
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