The use of biota sampling for environmental contaminant analysis for characterization of benthic communities in the Aleutians

It is increasingly clear that the public, native tribes, and governmental agencies are interested in assessing the well-being of natural resources and ecosystems. This may take the form of understanding species presence, monitoring population status and trends, measuring behavior, or quantifying physiology, biological stresses, or chemical/radiological exposure through biomarkers. Often there is a separation between understanding the biological aspects of species well-being and assessing exposure to contaminants. In this paper we examine the applicability of using scuba sampling aimed primarily at specimen collection for radionuclide analysis to assess species presence/absence and to compare among sampling sites and depths. We were especially interested in whether dive transects could provide information on species presence and potential exposure to environmental contaminants. In June/July 2004 we sampled at 49 depth stations along 19 transects at Amchitka and Kiska Islands in the western Aleutian Islands in the Northern Pacific/Bering Sea region. Amchitka Island, a former World War II U.S. Navy base, was the site of three underground nuclear test shots from 1965 to 1971. Four to six transects were established at three Amchitka sites and two Kiska Sites, and 2 to 4 stations were sampled on each transect. Bottom conditions, weather and currents prevented a complete sampling of all stations. There were interspecific differences in the percent of stations where biota were found and collected, in their occurrence near the three test shots on Amchitka, and in the depth where they were found. There were no significant differences between Amchitka and Kiska Island in the percent of stations where species were found. These data suggest that information gathered incidentally to the collection of specimens for chemical/radiological analysis can prove useful for understanding the presence of benthic organisms along particular transects, at given depths, and at different geographical locations. This information also provides a baseline for the range of organisms that could be exposed to future physical or chemical/radiological stressors. The data are useful for developing future biomonitoring plans to assess biological well-being and chemical/radiological exposure only if they are published and available to the public, public policy makers, and managers. Just as it is critical to select endpoints and bioindicators that are of interest for assessing both human and ecological health, specimens should be collected using a protocol that is useful for both chemical/radiological analysis and biological information.     

Antibiotic resistant enterococci and staphylococci isolated from flies collected near confined poultry feeding operations

Use of antibiotics as feed additives in poultry production has been linked to the presence of antibiotic resistant bacteria in farm workers, consumer poultry products and the environs of confined poultry operations. There are concerns that these resistant bacteria may be transferred to communities near these operations; however, environmental pathways of exposure are not well documented. We assessed the prevalence of antibiotic resistant enterococci and staphylococci in stored poultry litter and flies collected near broiler chicken houses. Drug resistant enterococci and staphylococci were isolated from flies caught near confined poultry feeding operations in the summer of 2006. Susceptibility testing was conducted on isolates using antibiotics selected on the basis of their importance to human medicine and use in poultry production. Resistant isolates were then screened for genetic determinants of antibiotic resistance. A total of 142 enterococcal isolates and 144 staphylococcal isolates from both fly and poultry litter samples were identified. Resistance genes erm(B), erm(A), msr(C), msr(A/B) and mobile genetic elements associated with the conjugative transposon Tn916, were found in isolates recovered from both poultry litter and flies. Erm(B) was the most common resistance gene in enterococci, while erm(A) was the most common in staphylococci. We report that flies collected near broiler poultry operations may be involved in the spread of drug resistant bacteria from these operations and may increase the potential for human exposure to drug resistant bacteria.     

A simple drought risk analysis procedure to supplement water resources management planning in England and Wales

The current ‘Deployable Output’ approach for assessing water resources system performance in England and Wales is a practical, communicable means for assessing the adequacy of a water supply system and determining the relative benefits of proposed system enhancements. A recognised flaw with this approach is that it fails to characterise the severity of potential supply shortfalls, leading to mischaracterisation of risks and benefits associated with alternative candidate investments. Here, we propose a Monte Carlo procedure that could supplement the existing process by exposing the magnitude (% water demand unserved) and duration (number of days) of supply curtailments under a range of drought scenarios. The method is demonstrated using a realistic, stylised water resources system and a discrete number of infrastructure investments. Results demonstrate that vulnerability assessments can expose previously unidentified risks that might radically alter a planner’s estimate of the cost‐effectiveness of a particular investment.     

Test method for minimum and maximum densities of small quantities of soil

The minimum and maximum void ratios are required to establish the relative density of sandy soil. Undisturbed simple shear test specimens are often too small to provide enough material to employ the Japanese Standard JIS A 1224:2009 Test Method. An alternative test method for evaluating the dry minimum and maximum densities of soil is proposed for those cases when a test specimen does not provide enough material to use the standard-size mold. The alternative test method was applied to soil from 42 small test specimens. Soil from test specimens of the same material were subsequently mixed to produce eight soil composites for which their minimum and maximum densities could be determined using both the standard and alternative methods. The minimum and maximum void ratios determined by both methods for the composite soil are in good agreement. Moreover, trends in the dataset are consistent with those from previous studies on sand and non-plastic fine-grained soil.     

Use of existing water, sediment, and tissue data to screen ecological risks to the endangered Rio Grande silvery minnow

A screening-level ecological risk assessment was applied to two extensive, but previously unanalyzed datasets from the middle Rio Grande (MRG) in New Mexico. The assessment evaluated how adverse water-quality effects from aquatic toxicants may have influenced the population decline of the endangered Rio Grande silvery minnow (Hybognathus amarus; silvery minnow). Standardized US Environmental Protection Agency (USEPA) screening-level ecological risk assessment procedures were applied to chemicals assessed in samples collected from the MRG between 1985 and 2003. Since more chemicals have established risk-screening criteria, relative to water-quality criteria, this approach produces more complete assessments. Chemical concentrations at some locations and times were potentially sufficient to affect fish health or produce localized mortalities. Many constituents displaying the highest risks have substantial natural sources within the watershed; native species likely would have adapted to natural instream concentrations such that actual risks might be markedly less than projected by a risk screening based on generic aquatic-life criteria. Also, highest risks found for individual and combinations of contaminants were very inconsistent both within and across the sites. As such, this risk assessment does not support the conclusion that toxicants were a primary factor causing the silvery minnow population to decline in the MRG between 1985 and 2003. The assessment indicates that sediment-borne, relative to water-borne, contaminants appeared to present the greatest risks to the silvery minnow and thus should have increased focus during future assessments of potential contaminant effects in the MRG. Contaminants of greatest concern are identified. This study presents approaches to cost-effectively assess and reduce uncertainties associated with potential water quality effects, and to help direct future assessments of water quality onto those contaminants likely to produce potentially significant effects. The techniques presented and criteria compiled are suitable for aiding similar assessments in other aquatic habitats.     

Development of microbial community structure and actvity in a high-rate anaerobic bioreactor at 18 degrees C

Anaerobic digestion in the psychrophilic (< 20 degrees C) or sub-mesophilic temperature range has recently been proven as an effective treatment option for the mineralization of a wide variety of problematic wastewaters. In this study, an expanded granular sludge bed-anaerobic filter (EGSB-AF) bioreactor was seeded with a full-scale, mesophilic sludge and employed to evaluate the long-term operational potential, and underlying microbial ecology, of this approach for the treatment of a medium-strength (5 g chemical oxygen demand [COD] l(-1)), synthetic, volatile fatty acid-based wastewater. Throughout the trial period of 625 days, extended intervals of consistently stable and efficient wastewater treatment were sustained. These results were highlighted by a short start-up period (21 d), low hydraulic retention times (4.88h), high organic (up to 24.64kg CODm(-3)d(-1)), and volumetric loading rates (up to 4.92 m3 m(-3) d(-1)). A stable, well-settling granular sludge bed was maintained in the bioreactor for the majority of the trial; however, reduced treatment efficiency and biomass washout were observed at an imposed OLR of 36.96 kg COD m(-3) d(-1). The microbial biomass in the bioreactor was investigated using maximum specific methanogenic activity assays and polymerase chain reaction-denaturing gradient gel electrophoresis. A temporal succession of both the bacterial and archaeal populations was noted during the trial, compared to the seed sludge, in response to bioreactor operation at lower temperatures, loading rate increases and to VFA accumulation in the bioreactor. During the trial, an increased contribution of hydrogenotrophic methanogenesis as a pathway of methane production was observed, along with the overall emergence of a highly active psychrotolerent-though still mesophilic biomass.     

Hot Surface Ignition of Performance Fuels

Ignition of flammable and combustible liquids by hot surfaces is a well-known hazard in motorsports where high-speed collisions and mechanical failures are common. In this paper, we present the results of 900 ignition tests of high performance fuels commonly used in motorsports applications including high-octane gasolines, nitromethane, and methanol. The results of the testing show that hot surface ignition is probabilistic in nature and cannot be defined by a single ignition temperature. It was found that hot surface ignition temperatures for the high-octane gasolines and methanol were several hundred degrees higher than published auto ignition temperatures for these fuels. While methanol has a higher octane number than standard gasolines, its hot surface ignition temperature was lower than gasoline. Nitromethane displayed ignition characteristics markedly different than the other fuels tested, igniting more than 200°C lower than gasoline blends and alcohols, and less than 50°C above its published auto ignition temperature.     

Low-fat, monounsaturate-rich diets reduce susceptibility of low density lipoproteins to peroxidation ex vivo

Oxidative modification of low density lipoprotein (LDL) plays an important role in the process of atherosclerosis. The susceptibility of LDL to oxidation and the amount of peroxidation products formed are influenced by the lipoprotein content of 18∶1 n−9, 18∶2n−6, and the 18∶2n−6/18∶1n−9 ratio, which is dependent in part on dietary fatty acids. The purpose of this study was to determine if changing from a typical American diet to a low-fat, monousaturate-rich diet (LFMR) would result in favorable alterations in the fatty acid composition and oxidative profile of LDL in hypercholesterolemic individuals. Free-living postmennopausal hypercholesterolemic women who routinely consumed a diet moderately high in total fat and total saturates (34 and 11%, respectively) followed an LFMR diet (26% fat, 6% saturated fat, and 14% monounsaturated fat) for 6 mon. Sixteen postmenopausal hypercholesterolemic women already following standard low-fat (LF) diets acted as a control for seasonal variations in serum lipids. LDL from randomly selected subjects (LF n=6, LFMR n=5) was evaluated. LFMR diets resulted in LDL with increased concentrations and percentages of 18∶1n−9, reduced 18∶2n−6/18∶1n−9 ratio, and lower percentages of 18∶2n−6. No significant changes in LDL fatty acids occurred in the LF group. Conjugated diene lag time increased in both groups during copper-induced in vitro oxidation. Only the LFMR group experienced an increase in lipid peroxide lag time and a decrease in lipid peroxide formation. The LFMR diet was well tolerated and may be of therapeutic value in the treatment of hypercholesterolemia. A portion of this material was presented earlier at the annual meeting of the American Oil Chemists' Society and in abstract form [O'Byrne, D.J., Shireman, R.B., Knauft, D. (1993) The effects of a low-fat/high oleic acid diet on lipoproteins in postmenopausal hypercholesterolemic women, INFORM 4:553,#SS7].     

Effects of Plant Identity and Chemical Constituents on the Efficacy of a Baculovirus Against Heliothis virescens

Baculoviruses are arthropod-specific, dsDNA viruses primarily used to control lepidopteran pests. A limitation of the use of baculoviruses for pest control is that their efficacy is modifiable by host-plant chemicals. The levels of phenolic substrates and two foliar oxidative enzymes, peroxidase (POD) and polyphenol oxidase (PTO), were significant predictors of disease caused by a baculovirus in Heliothis virescens fed on either cotton or lettuce; POD was the more influential of the two enzymes. The higher the plant phenolase activity, the lower the percent mortality and the slower the insects died from viral infection. Whether a particular class of phenolic substrates was correlated with enhanced or attenuated baculoviral disease depended upon context, i.e., admixture. Diminution of viral efficacy by plant oxidative activity may compromise the compatibility of baculoviruses with other components of an integrated pest management system such as host plant resistance.     

Effect of Nitrogen Availability on Expression of Constitutive and Inducible Chemical Defenses in Tomato, Lycopersicon esculentum

Young tomato plants (Lycopersicon esculentum) grown in sand in a greenhouse and subjected to different fertilization regimes were used to test the effects of nitrogen availability on constitutive levels of phenolics and on constitutive and inducible activities of polyphenol oxidase and proteinase inhibitors. Theories that emphasize physiological constraints on the expression of phytochemicals predict an increase in levels of carbon-based allelochemicals under moderate nitrogen stress but predict, under the same conditions, an attenuation of chemical responses involving nitrogen-containing compounds such as proteinase inhibitors and polyphenol oxidase. We found that nitrogen availability had a strong effect on constitutive levels of phenolics; weaker effects on constitutive polyphenol oxidase activity, constitutive proteinase inhibitor activity, and inducible polyphenol oxidase activity; and no effect on inducible proteinase inhibitor activity. These results point to a need for the integration of theories that emphasize physiological influences on secondary metabolism with those that emphasize ecological influences on secondary metabolism and suggest that current theories of plant defense do not adequately account for enzymatic and proteinaceous defenses against arthropods.