3 research outputs found
Fate of 4-Nonylphenol and 17β-Estradiol in the Redwood River of Minnesota
The majority of previous research investigating the fate of endocrine-disrupting
compounds has focused on single processes generally in controlled
laboratory experiments, and limited studies have directly evaluated
their fate and transport in rivers. This study evaluated the fate
and transport of 4-nonylphenol, 17β-estradiol, and estrone in
a 10-km reach of the Redwood River in southwestern Minnesota. The
same parcel of water was sampled as it moved downstream, integrating
chemical transformation and hydrologic processes. The conservative
tracer bromide was used to track the parcel of water being sampled,
and the change in mass of the target compounds relative to bromide
was determined at two locations downstream from a wastewater treatment
plant effluent outfall. In-stream attenuation coefficients (<i>k</i><sub>stream</sub>) were calculated by assuming first-order
kinetics (negative values correspond to attenuation, whereas positive
values indicate production). Attenuation of 17β-estradiol (<i>k</i><sub>stream</sub> = −3.2 ± 1.0 day<sup>–1</sup>) was attributed primarily due to sorption and biodegradation by
the stream biofilm and bed sediments. Estrone (<i>k</i><sub>stream</sub> = 0.6 ± 0.8 day<sup>–1</sup>) and 4-nonylphenol
(<i>k</i><sub>stream</sub> = 1.4 ± 1.9 day<sup>–1</sup>) were produced in the evaluated 10-km reach, likely due to biochemical
transformation from parent compounds (17β-estradiol, 4-nonylphenolpolyethoxylates,
and 4-nonyphenolpolyethoxycarboxylates). Despite attenuation, these
compounds were transported kilometers downstream, and thus additive
concentrations from multiple sources and transformation of parent
compounds into degradates having estrogenic activity can explain their
environmental persistence and widespread observations of biological
disruption in surface waters
Effects of an Extreme Flood on Trace Elements in River Waterî—¸From Urban Stream to Major River Basin
Major floods adversely affect water
quality through surface runoff,
groundwater discharge, and damage to municipal water infrastructure.
Despite their importance, it can be difficult to assess the effects
of floods on streamwater chemistry because of challenges collecting
samples and the absence of baseline data. This study documents water
quality during the September 2013 extreme flood in the South Platte
River, Colorado, USA. Weekly time-series water samples were collected
from 3 urban source waters (municipal tap water, streamwater, and
wastewater treatment facility effluent) under normal-flow and flood
conditions. In addition, water samples were collected during the flood
at 5 locations along the South Platte River and from 7 tributaries
along the Colorado Front Range. Samples were analyzed for 54 major
and trace elements. Specific chemical tracers, representing different
natural and anthropogenic sources and geochemical behaviors, were
used to compare streamwater composition before and during the flood.
The results differentiate hydrological processes that affected water
quality: (1) in the upper watershed, runoff diluted most dissolved
constituents, (2) in the urban corridor and lower watershed, runoff
mobilized soluble constituents accumulated on the landscape and contributed
to stream loading, and (3) flood-induced groundwater discharge mobilized
soluble constituents stored in the vadose zone
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