Chemical and biological tracers to identify source and transport pathways of septic system contamination to streams in areas with low permeability soils

Digaletos, Maria; Ptacek, Carol J.; Thomas, Joseph P.; Liu, Yingying

doi:10.1016/j.scitotenv.2023.161866

Cited by 3 publications

(2 citation statements)

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“…Eutrophication and its cascading effects (e.g., algal blooms, fish kills, habitat degradation, tourism, and other environmental and socioeconomic damages) continue to pose water quality challenges globally. These challenges have been documented in the United States (Rakhimbekova et al 2021;Herren et al 2021), Canada (Robertson et al 2021;Digaletos et al 2023), Spain (Pérez-Ruzafa et al 2019), Ethiopia (Menberu et al 2021), China (Wang et al 2019), France (Louis et al 2023), and other countries (Oliver et al 2018). Elevated nitrogen inputs from anthropogenic sources have been found to negatively affect river ecosystem functioning (Zhang and Chadwick 2022) and can endanger public health by increasing the risk of methemoglobinemia from consumption of elevated nitrate in drinking water (Raju and Singh 2017).…”

Section: Introductionmentioning

confidence: 99%

“…UN-Habitat and the WHO (2021) estimated that 24% of domestic wastewater generated worldwide flowed into a septic tank. Past studies have found that septic systems can be potentially significant sources of nutrients to groundwater and/or surface waters (Oldfield et al 2020;Buszka and Reeves 2021;Robertson et al 2021;Rakhimbekova et al 2021;Herren et al 2021;Digaletos et al 2023). Groundwater beneath drainfield trenches tends to be mostly nitrate and may be removed by denitrification beneath and/or hydrologically down-gradient from a drainfield.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying Nitrogen Treatment by an In-stream Bioreactor in a Watershed Served by Septic Systems

Iverson,

Humphrey,

O’Driscoll

et al. 2024

Environ. Process.

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Septic systems are potentially significant sources of nitrogen to groundwater and surface water. In-stream practices, such as in-stream bioreactors (IBRs), that promote or enhance nitrogen treatment are promising solutions to reduce nitrogen loads to nutrient-sensitive water. More work is needed to evaluate the efficiency of IBRs in new applications, such as residential sub-watersheds with a high-density of septic systems. The goal of this study was to quantify nitrogen treatment by an in-stream bioreactor (IBR) during baseflow conditions. The IBR was constructed in March 2017 when approximately 1 m of streambed sediment was excavated and backfilled with 0.75 m of woodchips capped by 0.2 m of rotary-kiln, expanded slate and boulder-sized riprap. Samples were collected monthly from July 2017 – March 2019 including IBR inflow, monitoring ports within the IBR, groundwater seeps draining to the IBR, and IBR outflow. Water samples were analyzed for total dissolved nitrogen (TDN), nitrate, ammonium, dissolved organic carbon, chloride, and nitrate isotopic fractionation. The IBR reduced the median concentration of TDN and nitrate by 40% and 77%, respectively. The median mass removal of TDN and nitrate was 26 and 5.2 g day− 1, respectively. Nitrogen-chloride ratios and isotopic fractionation data suggest that denitrification was likely a predominant nitrogen reduction mechanism. In addition to nitrogen treatment, the IBR provided other benefits by improving erosion control, streambank stabilization, and increased bank-full storage from 6 m3 to 19.2 m3. Results indicated that the IBR improved water quality and other residential sub-watersheds with septic systems would benefit from similar practices.

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