Is on-site wastewater a significant source of phosphorus to coastal plain streams?

Humphrey, Charles; O’Driscoll, Michael A.; Iverson, Guy; Anderson-Evans, Eliot

doi:10.1007/s13762-019-02477-2

Cited by 2 publications

(3 citation statements)

References 42 publications

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“…Outflow from the wetland contained an almost equal percentage of particulate (50.3%) and dissolved (49.7%) phosphorus. Median concentrations of TP in wetland inflow and outflow observed in this study were within the range of concentrations (0.08-0.13 mg/L) reported [14] for six streams monitored in Eastern NC that drained watersheds with residential development. The median phosphate concentration in wetland inflow (0.09 mg/L) was significantly greater (p = 0.01) relative to the median outflow concentration (0.03 mg/) and during just over 70% of sampling events, the outflow concentration was lower relative to inflow (Figure 13).…”

Section: Phosphorus Concentrations and Loadingsupporting

confidence: 70%

“…When SAV and algae die, waters can become depleted of dissolved oxygen during decomposition, resulting in a poor habitat for aquatic life and causing water use impairment. Some of the major sources of excess phosphorus loading to surface waters include agricultural runoff [8,9], livestock waste [10], urban runoff [11], municipal sewer discharges [12,13], septic systems [12,14], and wildlife waste [15]. Efforts to reduce the loading of nutrients from these sources is important for improving water quality and ecosystem health [2].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Phosphate and E. coli Attenuation in a Natural Wetland Receiving Drainage from an Urbanized Catchment

Humphrey,

Underwood,

Iverson

et al. 2024

Hydrology

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A natural wetland receiving drainage from a 24-ha urbanized catchment in the Falls Lake Watershed of North Carolina was evaluated to determine if it was providing ecosystem services with regards to phosphate and Escherichia coli (E. coli) attenuation. Inflow and outflow characteristics including nutrient and bacteria concentrations along with physicochemical properties (discharge, pH, oxidation reduction potential, temperature, and specific conductance) were assessed approximately monthly for over 2 years. The median exports of phosphate (0.03 mg/s) and E. coli (5807 MPN/s) leaving the wetland were 85% and 57% lower, respectively, relative to inflow loadings, and the differences were statistically significant (p < 0.05). Hydraulic head readings from three piezometers installed at different depths revealed the wetland was a recharge area. Phosphate and E. coli concentrations were significantly greater in the shallowest piezometer relative to the deepest one, suggesting treatment occurred during infiltration. However, severe erosion of the outlets is threatening the stability of the wetland. Upstream drainageway modifications were implemented to slow runoff, and septic system repairs and maintenance activities were implemented to improve water quality reaching the wetland and Lick Creek. However, more work will be needed to conserve the ecosystem services provided by the wetland.

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Section: Phosphorus Concentrations and Loadingsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Evaluation of Phosphate and E. coli Attenuation in a Natural Wetland Receiving Drainage from an Urbanized Catchment

Humphrey,

Underwood,

Iverson

et al. 2024

Hydrology

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“…Septic effluent contains potentially dangerous pathogens as well as concentrations of nitrogen, phosphorus, and pathogens can significantly impact environmental quality [5]. Septic systems often contribute excessive nitrogen and phosphorus loads to surface and ground waters, thereby exacerbating eutrophication and harmful algal blooms in freshwaters [6,7], changes in food web dynamics, and loss of biodiversity and habitat [8][9][10][11][12]. Further, excessive nitrate concentrations in drinking water resulting in methemoglobinemia or "blue baby syndrome" [13] and disease outbreaks (e.g., acute gastroenteritis) associated with poor septic tank performance have been reported globally [14,15].…”

Section: Introductionmentioning

confidence: 99%

Frontiers in assessing septic systems vulnerability in coastal Georgia, USA: Modeling approach and management implications

et al. 2021

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Threats to public health and environmental quality from septic systems are more prevalent in areas with poorly draining soils, high water tables, or frequent flooding. Significant research gaps exist in assessing these systems’ vulnerability and evaluating factors associated with higher rates of septic systems replacement and repair. We developed a novel GIS-based framework for assessing septic system vulnerability using a database of known septic system specifications and a modified Soil Topographic Index (STI) that incorporates seasonal high groundwater elevation to assess risks posed to septic systems in coastal Georgia. We tested the hypothesis that both the modified STI and septic system specifications such as tank capacity per bedroom and drainfield type would explain most of the variance in septic system repair and replacement using classification inference tree and generalized logistic regression models. Our modeling results indicate that drainfield type (level vs. mounded) is the most significant variable (p-value < 0.001) in predicting septic systems functionality followed by septic tank capacity per bedroom (p-value < 0.01). These show the importance of septic system design regulations such as a minimum requirement for horizontal separation distance between the bottom of trenches and seasonal water table, and adequate tank capacity design. However, for septic systems with a mounded drainfield and a larger tank capacity per bedroom, the modified STI representing hydrological characteristics of septic system location is a significant predictor of a high septic system repair and replacement rate. The methodology developed in this study can have important implications for managing existing septic systems and planning for future development in coastal areas, especially in an environment of rapid climatic change.

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Is on-site wastewater a significant source of phosphorus to coastal plain streams?

Cited by 2 publications

References 42 publications

Evaluation of Phosphate and E. coli Attenuation in a Natural Wetland Receiving Drainage from an Urbanized Catchment

Evaluation of Phosphate and E. coli Attenuation in a Natural Wetland Receiving Drainage from an Urbanized Catchment

Frontiers in assessing septic systems vulnerability in coastal Georgia, USA: Modeling approach and management implications

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