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Peter Shanahan. Ritter, Halle (Halle Caitlan) Massachusetts Institute of Technology. Department of Civil and Environmental Engineering. Massachusetts Institute of Technology. Department of Civil and Environmental Engineering a-si--- 2013-12-06T20:46:25Z 2013-12-06T20:46:25Z 2013 http://hdl.handle.net/1721.1/82824 863151944 Thesis (M. Eng.)--Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013. Cataloged from PDF version of thesis. Includes bibliographical references (pages 35-37). An investigation into the nitrogen chemistry of the anoxic layer of an urban constructed wetland in Singapore was conducted. This pilot-scale wetland treats stormwater runoff from the Balam Estate housing development for several water quality parameters of concern, including nitrate. Earlier sampling in the wetland had indicated that the concentration of nitrate was lower in the outflow from the rain garden than in its inflow, but no research had been done on other nitrogen species or transformation pathways. Preliminary analyses suggest that, although the saturated layer is sufficiently anoxic and denitrification is occurring as per performance objectives, organic nitrogen is being added to the infiltrating water throughout this layer, causing a net export of total nitrogen from the anoxic zone. This organic nitrogen could be either re-released from reserves adsorbed onto organic material during previous storm events, or leached directly from the anoxic layer material which includes wood chips and sand. Readings at outflow pipes indicate that a percentage of this nitrogen is likely re-mineralizing to ammonia upon exposure to more oxygen-rich conditions in the outflow pipes. Further study in the Balam Rain Garden using isotope labeling to more clearly delineate nitrogen fate and transport is suggested. by Halle Ritter. M.Eng. 41 pages eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Civil and Environmental Engineering. Nitrogen chemistry in an urban bioretention system in Singapore Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="bf23ceb7-510d-4a27-9189-9e934bfe9b1b"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Nitrogen chemistry in an urban bioretention system in Singapore</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2013</PublicationDate> <Authors> <Author> <DisplayName>Ritter, Halle (Halle Caitlan)</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Civil and Environmental Engineering.</Keyword> <Abstract>An investigation into the nitrogen chemistry of the anoxic layer of an urban constructed wetland in Singapore was conducted. This pilot-scale wetland treats stormwater runoff from the Balam Estate housing development for several water quality parameters of concern, including nitrate. Earlier sampling in the wetland had indicated that the concentration of nitrate was lower in the outflow from the rain garden than in its inflow, but no research had been done on other nitrogen species or transformation pathways. Preliminary analyses suggest that, although the saturated layer is sufficiently anoxic and denitrification is occurring as per performance objectives, organic nitrogen is being added to the infiltrating water throughout this layer, causing a net export of total nitrogen from the anoxic zone. This organic nitrogen could be either re-released from reserves adsorbed onto organic material during previous storm events, or leached directly from the anoxic layer material which includes wood chips and sand. Readings at outflow pipes indicate that a percentage of this nitrogen is likely re-mineralizing to ammonia upon exposure to more oxygen-rich conditions in the outflow pipes. Further study in the Balam Rain Garden using isotope labeling to more clearly delineate nitrogen fate and transport is suggested.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>