2 research outputs found
Persistence and Potential Effects of Complex Organic Contaminant Mixtures in Wastewater-Impacted Streams
Natural and synthetic organic contaminants in municipal
wastewater
treatment plant (WWTP) effluents can cause ecosystem impacts, raising
concerns about their persistence in receiving streams. In this study,
Lagrangian sampling, in which the same approximate parcel of water
is tracked as it moves downstream, was conducted at Boulder Creek,
Colorado and Fourmile Creek, Iowa to determine in-stream transport
and attenuation of organic contaminants discharged from two secondary
WWTPs. Similar stream reaches were evaluated, and samples were collected
at multiple sites during summer and spring hydrologic conditions.
Travel times to the most downstream (7.4 km) site in Boulder Creek
were 6.2 h during the summer and 9.3 h during the spring, and to the
Fourmile Creek 8.4 km downstream site times were 18 and 8.8 h, respectively.
Discharge was measured at each site, and integrated composite samples
were collected and analyzed for >200 organic contaminants including
metal complexing agents, nonionic surfactant degradates, personal
care products, pharmaceuticals, steroidal hormones, and pesticides.
The highest concentration (>100 μg L<sup>–1</sup>)
compounds
detected in both WWTP effluents were ethylenediaminetetraacetic acid
and 4-nonylphenolethoxycarboxylate oligomers, both of which persisted
for at least 7 km downstream from the WWTPs. Concentrations of pharmaceuticals
were lower (<1 μg L<sup>–1</sup>), and several compounds,
including carbamazepine and sulfamethoxazole, were detected throughout
the study reaches. After accounting for in-stream dilution, a complex
mixture of contaminants showed little attenuation and was persistent
in the receiving streams at concentrations with potential ecosystem
implications
Tapwater Exposures, Effects Potential, and Residential Risk Management in Northern Plains Nations
In the United States (US), private-supply tapwater (TW)
is rarely
monitored. This data gap undermines individual/community risk-management
decision-making, leading to an increased probability of unrecognized
contaminant exposures in rural and remote locations that rely on private
wells. We assessed point-of-use (POU) TW in three northern plains
Tribal Nations, where ongoing TW arsenic (As) interventions include
expansion of small community water systems and POU adsorptive-media
treatment for Strong Heart Water Study participants. Samples from
34 private-well and 22 public-supply sites were analyzed for 476 organics,
34 inorganics, and 3 in vitro bioactivities. 63 organics and 30 inorganics
were detected. Arsenic, uranium (U), and lead (Pb) were detected in
54%, 43%, and 20% of samples, respectively. Concentrations equivalent
to public-supply maximum contaminant level(s) (MCL) were exceeded
only in untreated private-well samples (As 47%, U 3%). Precautionary
health-based screening levels were exceeded frequently, due to inorganics
in private supplies and chlorine-based disinfection byproducts in
public supplies. The results indicate that simultaneous exposures
to co-occurring TW contaminants are common, warranting consideration
of expanded source, point-of-entry, or POU treatment(s). This study
illustrates the importance of increased monitoring of private-well
TW, employing a broad, environmentally informative analytical scope,
to reduce the risks of unrecognized contaminant exposures