Modeling Wetland Biogeochemistry and Restoration in South Florida
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The Ohio State University / OhioLINK
2015
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=osu1437578127 |
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NDLTD |
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English |
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Environmental Science Wetlands Biogeochemistry Restoration Everglades Modeling Phosphorus Mangroves |
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Environmental Science Wetlands Biogeochemistry Restoration Everglades Modeling Phosphorus Mangroves Marois, Darryl Evan Modeling Wetland Biogeochemistry and Restoration in South Florida |
| author |
Marois, Darryl Evan |
| author_facet |
Marois, Darryl Evan |
| author_sort |
Marois, Darryl Evan |
| title |
Modeling Wetland Biogeochemistry and Restoration in South Florida |
| title_short |
Modeling Wetland Biogeochemistry and Restoration in South Florida |
| title_full |
Modeling Wetland Biogeochemistry and Restoration in South Florida |
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Modeling Wetland Biogeochemistry and Restoration in South Florida |
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Modeling Wetland Biogeochemistry and Restoration in South Florida |
| title_sort |
modeling wetland biogeochemistry and restoration in south florida |
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The Ohio State University / OhioLINK |
| publishDate |
2015 |
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http://rave.ohiolink.edu/etdc/view?acc_num=osu1437578127 |
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AT maroisdarrylevan modelingwetlandbiogeochemistryandrestorationinsouthflorida |
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1719438711493492736 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu14375781272021-08-03T06:32:07Z Modeling Wetland Biogeochemistry and Restoration in South Florida Marois, Darryl Evan Environmental Science Wetlands Biogeochemistry Restoration Everglades Modeling Phosphorus Mangroves <p>Wetlands are an integral component of watersheds and their surrounding landscape. They provide numerous ecosystem services to humans and the environment including water treatment, flood mitigation, and wildlife habitat. Despite this, urban development and agriculture have been impacting these valuable ecosystems for centuries, impacting the services they can provide. The wetlands of south Florida, including the greater Florida Everglades, provide a unique landscape of different wetland types that have all been adversely impacted by human activities. This dissertation assesses the ecosystem services provided by freshwater marshes and coastal mangroves through ecosystem modeling to better understand how to restore and manage these systems to maximize these services. Computer modeling of nutrient dynamics and hydrology is used as an integral tool in achieving these objectives.</p><p>The dynamics of the ecosystem service of phosphorus retention in constructed wetlands were investigated in three-year study of 18 mesocosms located in south Florida. These mesocosms received water daily from the outflow of a constructed stormwater treatment area designed to retain phosphorus. The mesocosms were planted with six different vegetation communities with three replications of each community. The planted vegetation communities included monocultures of cattail (<i>Typha domingensis</i>), sawgrass (<i>Cladium jamaicense</i>), and water lily (<i>Nymphaea odorata</i>); a mixture of the submersed aquatic vegetation (SAV) consisting of Southern naiad (<i>Najas guadalupensis</i>) and the algae Chara (<i>Chara</i> sp.); a mixture of water lily and spikerush (<i>Eleocharis cellulosa</i>); and control mesocosms that were not planted and only filled with soil and water. We used diurnal dissolved oxygen measurements to calculate aquatic metabolism in these mesocosms and then compared these calculations to water quality measurements. In 2012, the control mesocosms had significantly higher aquatic gross primary production (GPP) at 7.0 g O<sub>2</sub> m<sup>-2</sup> d<sup>-1</sup> than all other communities. Mesocosms planted with water lily and those planted with SAV had significantly higher GPP (5.5 and 5.9 g O<sub>2</sub> m<sup>-2</sup> d<sup>-1</sup>, respectively) than those planted with cattail, water lily/spikerush, and sawgrass (1.7, 2.3, and 1.5 g O<sub>2</sub> m<sup>-2</sup> d<sup>-1</sup>, respectively). Rates of phosphorus cycling due to aquatic metabolism were estimated to range from 2.5 g P m<sup>-2</sup> yr<sup>-1</sup> in both the sawgrass and water lily/spikerush communities to 7.7 g P m<sup>-2</sup> yr<sup>-1</sup> in the naturally colonized mesocosms. These results provide evidence that wetland plant communities without high-biomass emergent macrophytes may perform best in the retention of phosphorus in low inflow concentration conditions.</p><p>A mechanistic model of phosphorus dynamics was then built in the modeling software STELLA using data collected from the same mesocosms. Inputs into the model included water, soil, weather, and plant data from the study. The model consists of three interconnected submodels: plant growth, hydrology, and phosphorus dynamics. The model simulates processes in water and soil related to all four forms of phosphorus: dissolved organic, dissolved inorganic, particulate organic, and particulate inorganic. Model verification and subsequent calibration was performed using biweekly outflow water quality data from the mesocosm planted with an SAV community. Model validation was then conducted using data from the mesocosms planted with cattail, sawgrass, and water lily. The model was able to simulate outflow concentrations of total phosphorus from all four plant communities with average relative errors of less than 35%. A sensitivity analysis revealed the relative importance of the various processes involved in the retention of all P forms and the effects of different vegetation communities on these processes. Further simulations were run to predict the outflow total P concentrations for an additional year and the effects of varied P loading. These simulations showed that with enough time, the proper plant community (a mix of water lily and SAV in this case), and the appropriate phosphorus loading rate, it may be possible to consistently reach total phosphorus outflow concentrations as low as 10 ppb.</p><p>The ecosystem service of coastal protection provided by mangrove wetlands was assessed through a systematic review of published results of observational studies and modeling experiments. We outlined our findings based on methodology and event type and concluded that observational studies have not provided conclusive results on the extent of coastal protection provided by mangroves from extreme natural disasters. We found, however, that results from several recent numerical and physical models support the mitigating capabilities of mangroves for cyclone storm surges and small tsunamis. Additionally, studies on the economic valuation of mangroves have estimated coastal protection to be a major portion of their total value. We concluded that further research utilizing robust datasets for multivariate statistical analyses and validation of numerical models is still needed to provide a better assessment of the feasibility of incorporating mangroves into coastal protection plans.</p><p>Altering the hydrology of a mangrove ecosystem can have severe consequences for its ecological function and resilience to common coastal disturbances. Mangroves rely on tides to provide nutrients and flush toxins, and they also need freshwater inflows to prevent high salinities. Using field sampling and remote-sensing we assessed the hydrologic conditions of an impacted mangrove system in Naples, Florida and concluded the hydrology of had been significantly altered from its historic state due to urban development. A restoration plan was then proposed utilizing hydraulic modeling to aid in its design and the prediction of its hydrologic outcomes. The proposed restoration plan would extend the existing creek channel 1.1 km inland through an adjacent mangrove forest and up an the inland marsh area. Using the Hydrologic Engineering Center’s River Analysis System, we calibrated a hydraulic model of the mangrove creek using tidal data from Naples Bay and water levels measured within the creek. The calibrated model was then used to simulate the resulting hydrology of our proposed restoration plan. The simulation results showed that the proposed creek extension would restore a twice-daily flooding regime to a majority of the adjacent mangrove forest. This study demonstrated the utility provided by hydraulic models combined with field data to aid in the design of a rehabilitation plan and to predict the outcomes of implementing the plan.</p> 2015-10-15 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1437578127 http://rave.ohiolink.edu/etdc/view?acc_num=osu1437578127 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |