Emissions of reduced sulphur compounds from the surface of primary and secondary wastewater clarifiers at a Kraft Mill

Emissions of reduced sulphur compounds (RSCs) from the primary and secondary clarifiers at a Kraft mill were measured for respectively 8 and 22 days using a floating flux chamber. In the primary clarifier, dimethyl disulphide (DMDS) had the highest mean flux (0.83 microg s(-1) m(-2)) among all RSCs, and the mean flux of total reduced sulphur (TRS) was 1.53 microg s(-1) m(-2). At the secondary clarifier, dimethyl sulphide (DMS) had the highest mean flux (0.024 microg s(-1) m(-2)), and the mean flux of total reduced sulphur (TRS) was 0.025 microg s(-1) m(-2). Large variations in fluxes as a function of sampling date were observed in both clarifiers. Emission fluxes of DMS from the secondary clarifier were correlated with temperature in the flux chamber and with the biological and chemical oxygen demands (BOD and COD) of the wastewater. Emission rates of RSCs from the clarifiers were found to be insignificant by comparison with other mill sources.     

Chemical contamination assessment of Gulf of Mexico oysters in response to hurricanes Katrina and Rita

Hurricane Katrina made landfall on August 29, 2005 and caused widespread devastation along the central Gulf Coast states. Less than a month later Hurricane Rita followed a similar track slightly west of Katrina’s. A coordinated multi-agency response followed to collect water, sediment and tissue samples for a variety of chemical, biological and toxicological indicators. The National Oceanic and Atmospheric Administration’s National Status and Trends Program (NS&T) participated in this effort by measuring chemical contamination in sediment and oyster tissue as part of the Mussel Watch Program, a long-term monitoring program to assess spatial and temporal trends in a wide range of coastal pollutants. This paper describes results for contaminants measured in oyster tissue collected between September 29 and October 10, 2005 and discusses the results in the context of Mussel Watch and its 20-year record of chemical contamination in the region and the nation. In general, levels of metals in oyster tissue were higher then pre- hurricane levels while organic contaminants were at or near record lows. No contaminant reported here exceeded the FDA action level for food safety.     

Evaluation of short-term Ogawa passive, photolytic, and federal reference method sampling devices for nitrogen oxides in El Paso and Houston, Texas

Passive Sampling Devices (PSDs) have been successfully used by government and academic agencies to monitor common ambient air pollutants such as ozone and nitrogen dioxide (NO(2)). Most PSD studies have involved long-term (e.g. bi-weekly or monthly) sampling. But the Passive Ozone Network of Dallas (POND) studies of 1998 and 1999 showed that high quality 24-hour and 12-hour data using the Ogawa PSD could be collected for ambient ozone concentrations. This paper presents an evaluation of short-term passive sampling results for nitrogen oxides (NO(x)) in El Paso and Houston, Texas, using the Ogawa PSD. The Ogawa NO(x) PSDs were compared to both Federal Reference Method (FRM) monitors and a photolytic converter, with the photolytic converter designed to report closer concentrations to "true" NO(x) by more effectively limiting the interferences of other nitrogen species. Overall, good agreement was noted for all three monitor types in both cities, supporting the potential use of lower cost Ogawa PSDs for large multi-site episodic NO(x)/NO(2)/NO saturation screening studies. This evaluation was conducted during two separate six week periods of the cooler winter months so additional testing of the Ogawa PSDs during different seasons is recommended.     

Model for estimation of traffic pollutant levels in northern communities

Using models to estimate the contribution of traffic to air pollution levels from known traffic data typically requires the knowledge of model parameters such as emission factors and meteorological conditions. This paper presents a state-space model analysis method that does not require the knowledge of model parameters; these parameters are identified from measured traffic and ambient air quality data. This method was used to analyze carbon monoxide (CO) in downtown Fairbanks, AK, which is the community of focus for this paper. It was found that traffic contributed, on average, 53% to the total CO levels over the last six winters. The correlation coefficient between the measured and model-predicted daily profiles of the CO concentration was 0.98, and the results were in good agreement with earlier findings obtained via a thorough CO emission inventory. This justified the usability of the method and it was further used to analyze fine particulate matter (PM2.5) in downtown Fairbanks. It was found that traffic contributed, on average, approximately 30% to the total PM2.5 levels over the last six winters. The correlation coefficient between the measured and model-predicted daily profiles of the PM2.5 concentration was 0.98.     

Simultaneous analysis of tissue- and genotype-specific variation in Solidago altissima (Asteraceae) rhizome terpenoids, and the polyacetylene dehydromatricaria ester

Solidago altissima is a dominant perennial of old field succession in North America with the ability to form dense, almost monospecific stands; the plant is also considered an aggressive invasive throughout Europe and Japan. S. altissima’s success is facilitated by large belowground rhizome systems that allow clonal spread and possible allelopathic suppression of competitors. A diversity of polar and nonpolar terpenes and polyacetylenes have been described from S. altissima rhizomes; however, there is little information documenting the concentration or distribution of these allelochemicals and how they relate to plant defense hypotheses. We thus developed a GC–MS method to simultaneously quantify rhizome terpenes and polyacetylenes that spanned a range of polarities and confirmed the presence of 19 terpenoids in addition to the polyacetylene dehydromatricaria ester (DME). We, (1) determined relative concentrations and variability of mono-, sesqui-, neutral diterpenes, diterpene acids and DME within a central NY population; (2) compared accumulation of these compounds in differently developed rhizome tissue; and (3) tested the alleopathic effect of DME at naturally occurring concentrations on germination and seedling growth of Asclepias syriaca, a common competitor of S. altissima. Overall, diterpene acids dominated the phytochemical profile of most genotypes (averaging 0.75% of fresh mass) with kolavenic acid being the single most abundant component. Monoterpene, sesquiterpene and acidic diterpene concentrations were all significantly greater in the actively elongating (current-year) rhizomes compared to established rhizomes and followed optimal defense theory predictions. Conversely, DME levels were lower in the current-year rhizomes than in established rhizomes. DME inhibited seed germination of A. syriaca in a dose-dependent manner. The tissue-specific accumulation of the different compounds may represent a biosynthetic and/or allocational strategy that limits the exposure of young-tissue to high concentrations of DME possibly limiting the cytotoxic effects of DME.     

Coastal scenic assessment: unlocking the potential for coastal tourism in rural Pakistan via Mediterranean developed techniques

Originally developed within the Mediterranean, a tested coastal management and planning tool was applied outside the region to evaluate its international scope, with particular reference to a less developed country. Seven coastal sites in Pakistan were investigated for their scenic values through a 26 item checklist grouped as physical and human parameters analysed though weighted parameters and fuzzy logic matrices. With respect to a five-class evaluation system, results indicated: Jiwani, Miani Hor and Pasni-Astola Island as extremely attractive natural sites with very high landscape value (classified as Class 1 sites); Mubarak village as an attractive natural site with high landscape value (classified as a Class 2 site); Kaka pir village, Harjana village and Keti Bandar as having little outstanding landscape features or with urban environment and classified as Class 3 sites. Rural and/or urban environmental influences were observed to be critical factors which influenced major human parameters that ultimately affect sites’ scenic classification. However, notwithstanding natural attraction, unless political and social development barriers are tackled in conjunction with recognising areas that possess inherent tourism potential, economic potential is unlikely to be realised.     

Parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians

While often studied in isolation, host-parasite interactions are typically embedded within complex communities. Other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g., the dilution effect), yet few studies have experimentally evaluated more than one such mechanism. Here, we used data from natural wetlands to design experiments investigating how alternative hosts and predators of parasites mediate trematode (Ribeiroia ondatrae) infection in a focal amphibian host (Pseudacris regilla). In short-term predation bioassays involving mollusks, zooplankton, fish, larval insects, or newts, four of seven tested species removed 62-93% of infectious stages. In transmission experiments, damselfly nymphs (predators) and newt larvae (alternative hosts) reduced infection in P. regilla tadpoles by -50%, whereas mosquitofish (potential predators and alternative hosts) did not significantly influence transmission. Additional bioassays indicated that predators consumed parasites even in the presence of alternative prey. In natural wetlands, newts had similar infection intensities as P. regilla, suggesting that they commonly function as alternative hosts despite their unpalatability to downstream hosts, whereas mosquitofish had substantially lower infection intensities and are unlikely to function as hosts. These results underscore the importance of studying host-parasite interactions in complex communities and of broadly linking research on predation, biodiversity loss, and infectious diseases.     

Above- and belowground responses of Arctic tundra ecosystems to altered soil nutrients and mammalian herbivory

Theory and observation indicate that changes in the rate of primary production can alter the balance between the bottom-up influences of plants and resources and the top-down regulation of herbivores and predators on ecosystem structure and function. The exploitation ecosystem hypothesis (EEH) posited that as aboveground net primary productivity (ANPP) increases, the additional biomass should support higher trophic levels. We developed an extension of EEH to include the impacts of increases in ANPP on belowground consumers in a similar manner as aboveground, but indirectly through changes in the allocation of photosynthate to roots. We tested our predictions for plants aboveground and for phytophagous nematodes and their predators belowground in two common arctic tundra plant communities subjected to 11 years of increased soil nutrient availability and/or exclusion of mammalian herbivores. The less productive dry heath (DH) community met the predictions of EEH aboveground, with the greatest ANPP and plant biomass in the fertilized plots protected from herbivory. A palatable grass increased in fertilized plots while dwarf evergreen shrubs and lichens declined. Belowground, phytophagous nematodes also responded as predicted, achieving greater biomass in the higher ANPP plots, whereas predator biomass tended to be lower in those same plots (although not significantly). In the higher productivity moist acidic tussock (MAT) community, aboveground responses were quite different. Herbivores stimulated ANPP and biomass in both ambient and enriched soil nutrient plots; maximum ANPP occurred in fertilized plots exposed to herbivory. Fertilized plots became dominated by dwarf birch (a deciduous shrub) and cloudberry (a perennial forb); under ambient conditions these two species coexist with sedges, evergreen dwarf shrubs, and Sphagnum mosses. Phytophagous nematodes did not respond significantly to changes in ANPP, although predator biomass was greatest in control plots. The contrasting results of these two arctic tundra plant communities suggest that the predictions of EEH may hold for very low ANPP communities, but that other factors, including competition and shifts in vegetation composition toward less palatable species, may confound predicted responses to changes in productivity in higher ANPP communities such as the MAT studied here.     

Microtox assay to determine the toxicity of degradation products from degradable plastics

Six types of starch-polyethylene degradable plastics were evaluated for the release of water-soluble toxic compounds under accelerated degradation conditions. A plastic strip (2.5×15.2 cm) was placed in a 250-ml Erlenmeyer flask with 100 ml of ASTM type I water with or without trace element solutions and shaken at 65°C and 110 rpm for 20 weeks in replicates of two. High temperature was used to accelerate the oxidative degradation of polyethylene. Plastic degradation was measured by loss of tensile strength, percentage elongation, strain energy, and weight-average molecular weight. The most rapid period of polyethylene thermal degradation was complete for most materials by day 28. Ten-milliliter aqueous samples were removed from each flask at days 1, 7, 28, 56, 84, and 140 (water volumes were maintained at 100 ml with fresh type I water), filtered through glass filters, then evaluated by using the Microtox Toxicity Analyzer (Microbics Corporation, Carlsbad, CA). No water-soluble toxic compounds were detected during the period of rapid film degradation. Toxicity was observed at day 28 for one film and at day 84 for all films, which could possibly correlate with the release of small oxidative compounds such as formaldehyde and acetaldehyde. Because of the sensitivity of this assay, positive results must be confirmed by otherin vitro studies.Journal Paper No. J-14851 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Projects No. 2889 and 0178.