The decay rates of enteric waterborne pathogens were evaluated following the introduction of Yersinia enterocolitica, Salmonella enterica, Campylobacter jejuni and Arcobacter butzleri into river water at different temperatures (5, 15 and 25°C) for a period of 28 days. To improve the accuracy of the results a molecular viability assay, long amplicon propidium monoazide-polymerase chain reaction (PMA-PCR), was used to quantify the viable cell concentration and results from PCR with and without PMA were compared. As well, the effect of background microbiota was assessed for Y. enterocolitica and S. enterica by inoculating cells into sterile and non-sterile river water. Cell persistence was improved by up to 4 log for Y. enterocolitica and 4.5 log for S. enterica in sterile river water compared to natural river water, showing that the autochthonous biological activity in river water can accelerate the die-off of introduced bacteria. Results also showed that low temperature significantly improved the persistence of all four target bacteria in non-sterile river water. There was a more rapid decline in cell concentration in samples with PMA pretreatment; therefore using PMA-PCR analysis can provide more reliable data on viable/active enteric bacteria in aquatic microcosms and allows for improved assessment of pathogens in the environment.
Received for publication October 19, 2008. Consuming pathogen-contaminated groundwater has caused many waterborne disease worldwide. Microspheres are often used as pathogen surrogates because they can be made similar to pathogens in terms of their sizes, buoyant densities, and shapes. Laboratory studies have, however, shown that the surface charges of microspheres are very different from those of pathogens of comparable sizes, and that their attenuation and transport behaviors differ significantly to those of the...
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A combined approach employing comet assay and micronucleus (MN) and sister chromatid exchanges (SCE) tests was utilized to
assess the genotoxicity of two pesticides, imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitro-imidazolidin-2-ylideneamine] and RH-
5849 [20-benzoyl-10-tert-butylbenzoylhydrazine], on human peripheral blood lymphocytes in vitro. No significant difference in the
frequencies of MN and SCE from the negative groups (P40.05) was observed at low dose levels...
The properties of aquatic dissolved organic matter (DOM) isolated by solid phase extraction (SPE) C-18 cartridges, ultrafiltration, and XAD chromatography are compared. Samples taken from the Suwannee River, Georgia, USA and McDonalds Branch in the Pine Barrens, New Jersey, USA were chosen to represent waters where DOM originates from predominantly terrestrially-derived (allochthonous) precursors. Pony Lake, Antarctica represented an exclusively algal/microbially-derived (autochthonous) DOM. Fluorescence, UV...
The biotechnology revolution is impacting all of the biological sciences, and toxicology is no exception. Perusal of the abstracts of the Society’s recent annual meetings confirms that our field is already actively using the powerful new tools of molecular biology to identify and understand the mechanisms of toxic responses. Thus, the Workshop on Toxicogenomics and Risk Assessment sponsored by the Society and discussed in this issue by Cunningham et al. was a timely undertaking.
This was not the first workshop...
Up to now, the recovery of precious metals used as catalysts in chemical processes has involved the use of incineration. Now, however, a British-Swedish joint venture has developed a process which uses supercritical water oxidation instead, which provides many economic and environmental advantages.
Precious metals are used extensively in catalysts in a wide range of industrial chemical processes. Sometimes they are used in a homogeneous form, but more often fixed to a solid support for ease of handling. In many...
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ABSTRACT: Reductive dechlorination of chlorinated organic compounds can be
promoted through the addition of electron donors to the subsurface. The presence
of ferric iron that is bioavailable can affect reductive dechlorination by supporting
the growth of iron-reducing bacteria. These bacteria can maintain sufficiently low
dissolved hydrogen concentrations to prevent reductive dechlorination of cisdichloroethene
(cDCE) for example. Evaluation of data from 13 sites that have...
The maps in this atlas depict the waters within each state that do not meet state water quality standards. States listed these waters in their most recent submission to EPA, generally in 1998, as required by section 303(d) of the Clean Water Act. This provision of the Clean Water Act requires a “Total Maximum Daily Load” or TMDL for each listed water. There are more than 20,000 such waters identified nationally, comprising more than 300,000 miles of rivers and streams and more than 5 million acres of lakes. The...
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Introduction
Sewage sludge originates from the process of treatment of waste water. Due to the physical-chemical processes involved in the treatment, the sludge tends to concentrate heavy metals and poorly biodegradable trace organic compounds as well as potentially pathogenic organisms – viruses, bacteria etc. – present in waste water.
Sludge is, however, rich in nutrients such as nitrogen and phosphorus and contains valuable organic matter that is useful when soils are depleted or...
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The inactivation of Cryptosporidium parvum in finished drinking water by medium-pressure UV light (200-300 nm) has been investigated at both the bench scale, using a collimated beam apparatus, and at the demonstration scale, using a Calgon Carbon Corporation Sentinel™ system at the Mannheim Water Treatment Plant, Kitchener, ON, Canada. The viability of the oocysts was assessed using both in vitro (fluorogenic vital dyes (DAPI/PI) and maximized in vitro excystatio...
Abstract This paper presents data on the source of PCDDs/PCDFs in cement plant stack emissions, demonstrating that these emissions are not necessarily all created by the process. The data potentially demonstrates that some of the PCDDs/PCDFs in the emissions are pre-existing dioxins and furans that are vaporized out of the kiln raw feed. This calls into question the assumption that PCDD/PCDF emissions can be decreased below a certain point. The EPA has acknowledged resuspended PCDD/PCDF emissions, such as from...
SummaryWaste discharges from municipal sewage treatment plants are a significant source of water quality problems throughout the country. States report that municipal discharges are the main source of impairment to estuaries and coastal waters, the second leading source of impaired rivers and streams, and also are a major source of pollution in lakes. Pollutants associated with municipal discharges include nutrients (which can stimulate growth of algae that deplete dissolved oxygen in surface water), bacteria and...
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