Web Release Date: July 18,
Steroid Estrogens, Nonylphenol Ethoxylate Metabolites, and Other Wastewater Contaminants in Groundwater Affected by a Residential Septic System on Cape Cod, MA
and
Silent Spring Institute, 29 Crafts St., Newton, Massachusetts 02458, Stockholm Environment Institute, U.S. Centre, P.O. Box 53103, Medford, Massachusetts 02153, Marine Science Research Center, Stony Brook University, Stony Brook, New York 11794-5000, U.S. Geological Survey, 3215 Marine St., Boulder, Colorado
Received for review December 28, 2005
Revised manuscript received May 2, 2006
Accepted June 9, 2006
Abstract:
Septic systems serve approximately 25% of U.S. households
and may be an important source of estrogenic and other
organic wastewater contaminants (OWC) to groundwater.
We monitored several estrogenic OWC, including
nonylphenol (NP), nonylphenol mono- and diethoxycarboxylates (NP1EC and NP2EC), the steroid hormones 17
-estradiol (E2), estrone (E1) and their glucuronide and sulfate
conjugates, and other OWC such as methylene blue
active substances (MBAS), caffeine and its degradation
product paraxanthine, and two fluorescent whitening agents
in a residential septic system and in downgradient
groundwater. E1 and E2 were present predominantly as
free estrogens in groundwater, and near-source groundwater
concentrations of all OWC were highest in the suboxic
to anoxic portion of the wastewater plume, where
concentrations of most OWC were similar to those observed
in the septic tank on the same day. NP and NP2EC were
up to 6- to 30-fold higher, and caffeine and paraxanthine
were each 60-fold lower than septic tank concentrations,
suggesting net production and removal, respectively, of these
constituents. At the most shallow, oxic depth, concentrations
of all OWC except for NP2EC were substantially lower
than in the tank and in deeper wells. Yet boron, specific
conductance, and the sum of nitrate-and ammonia-nitrogen
were highest at this shallow depth, suggesting preferential
losses of OWC along the more oxic flow lines. As far
as 6.0 m downgradient, concentrations of many OWC were
within a factor of 2 of near-source concentrations. The
results suggest that there is the potential for migration of
these OWC, which are unregulated and not routinely
monitored, in groundwater.
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