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Full-Text Articles in Life Sciences

Transport And Fate Of Phosphorus In The Nearshore Zone Of Lake Michigan, Nathan Van Ee Dec 2021

Transport And Fate Of Phosphorus In The Nearshore Zone Of Lake Michigan, Nathan Van Ee

Theses and Dissertations

Bioavailable phosphorus loads exported to Lake Michigan from the Milwaukee and Sheboygan River Watersheds appear to have increased in the last 40 years despite meeting total phosphorus (TP) loading goals set by the Great Lakes Water Quality Agreement (GLWQA).Overall, bioavailability of P delivered from the Milwaukee and Sheboygan Rivers was highest during the warmer months, which coincides with the nearshore nuisance algae growth season. However, first order loss rates of SRP calculated during baseflow recession were also greatest during the summer, suggesting that increased river residence time during the summer could reduce export of bioavailable P. Observations of phosphorus partitioning …


Hydrologic Controls On Phosphorus Speciation And Mobilization In A Subalpine Watershed (East River, Colorado), Lucia Isobel Arthen-Long Oct 2021

Hydrologic Controls On Phosphorus Speciation And Mobilization In A Subalpine Watershed (East River, Colorado), Lucia Isobel Arthen-Long

Masters Theses

The cycling of phosphorus (P) through floodplain environments is critical to ecosystem productivity and has significant implications on both water quality and soil fertility. P export from soils in response to saturation has been well documented, but the relative vulnerability of specific P pools to mobilization remains poorly constrained, as do the mechanisms mediating its release. The prediction of P availability in and export from mountainous floodplain soils is of great importance as global climate change is projected to significantly alter precipitation regimes in alpine systems. This study combined a thorough characterization of P distribution across a hillslope to floodplain …


Spatial And Temporal Variability In Carbon And Nutrient Concentrations Within The North Inlet Estuary,Sc, Heather Kish Oct 2021

Spatial And Temporal Variability In Carbon And Nutrient Concentrations Within The North Inlet Estuary,Sc, Heather Kish

Theses and Dissertations

Coastal wetlands provide numerous ecosystem services, including the ability to sequester and store significant amounts of organic carbon (so-called “blue carbon”). Variability in carbon storage within marshes represents a major information gap in understanding and quantifying the role saltmarshes play in the global carbon cycle. This study quantified decadal and small-scale variability in carbon and nutrient concentrations across tidal inundation gradients in the relatively pristine North Inlet Estuary, South Carolina. Sampling took place within two segments of the marsh platform of Crab Haul Creek, the landward-most basin within North Inlet. In the summer of 2020, a total of 200 sediment …


Plastic In Agricultural Soils And Its Biological Impacts, Olivia Mckay Aug 2021

Plastic In Agricultural Soils And Its Biological Impacts, Olivia Mckay

Master of Science in Environmental Sciences and Management Projects

Agricultural plastic mulch reduces weeds, yields higher crop quality and quantity, and increases soil temperature, but it can also become a soil pollutant. The impact of agricultural plastic contamination on soil microbial activity remains poorly documented. To better understand how plastic pollution influences soil microbial decomposers, we sampled three farms in Watsonville, CA. Each site is characterized by large amounts of plastic contamination in the form of polyethylene mulch and polyvinyl chloride dripline. The fields contain marked amounts of macro- (and presumably micro-) plastic fragments primarily derived from PVC dripline and polyethylene mulch. We haphazardly collected 6" deep soil samples …


The Quantitative Assessment Of Pond Scum: An Examination Of The Biogeochemistry Of Phosphorus Cycling In The Belgrade Lakes, Abbey M. Sykes Jan 2021

The Quantitative Assessment Of Pond Scum: An Examination Of The Biogeochemistry Of Phosphorus Cycling In The Belgrade Lakes, Abbey M. Sykes

Honors Theses

The internal recycling phosphorus in freshwater lake bottom sediments represents a significant source of hypolimnetic phosphorus (P) release for many of Maine’s lakes. In summer months, Maine lakes often thermally stratify and the lake hypolimnion develops anoxia, leading to a reduction in redox potential at the sediment-water interface. These reducing conditions facilitate the reductive dissolution of ferric iron, and, since phosphorus is often present in freshwater lake sediments as solid FeOOH-PO4 complexes, results in release of soluble phosphorus into the water column. Our current study presents field and laboratory data from sediment fractionation extractions designed to quantify concentrations of …


Nitrogen Dynamics And Transport Along Flowpaths In A Rural Wetland-Stream Complex, Colton Kyro Jan 2021

Nitrogen Dynamics And Transport Along Flowpaths In A Rural Wetland-Stream Complex, Colton Kyro

Graduate Student Theses, Dissertations, & Professional Papers

Human activities have doubled the rate of nitrogen inputs onto the landscape resulting in elevated nitrogen concentrations in our streams. Anthropogenically applied nitrogen is largely transported to stream networks via groundwater movement. Groundwater discharge occurs in distinct points along a stream but whose influences can often persist far beyond that area due to insufficient biogeochemical removal of imported nitrogen potentially causing alterations in community structure and precipitating large algae blooms. To understand the factors governing nitrogen abundance in a historical polluted stream, I used a mass-balance approach to quantify groundwater-surface water interaction and the magnitude of groundwater nitrogen input and …