Long-term atmospheric deposition of current-use and banned pesticides in Atlantic Canada; 1980-2000

The occurrence of current-use and banned pesticides is reported in wet-precipitation collected from four sites across Atlantic Canada during the period 1980-2000. The most frequently detected compounds were alpha-HCH, gamma-HCH (lindane), chlorothalonil, pentachlorophenol, atrazine, and endosulfan. Median site concentrations varied between not-detected and 10.2 ng l(-1). Deposition of HCHs (hexachlorocyclohexane), chlorothalonil, and endosulfan at Kejimkujik (Keji) and Jackson, Nova Scotia, were generally similar. Significant spatial differences (p<0.05), however, were found for the HCH isomers and endosulfan at Keji and Gros Morne (Newfoundland and Labrador), areas geographically separated by the northern Gulf of St. Lawrence. Long-term deposition of alpha-HCH decreased (p<0.05) at both Keji (1980-2000) and Gros Morne (1994-2000), with half-lives of 5.9 and 4.5 y, respectively. A decreasing trend was also found for pentachlorophenol with a half-life of 4.9 y at Jackson. Significant negative trends (p<0.05) were observed for alpha-/gamma-HCH ratios during the study at Keji and Jackson, possibly reflecting changes in production and use patterns of technical HCH and lindane on a continental and perhaps hemispheric scale. Seasonal trends for alpha-HCH and gamma-HCH were found to vary over the 20-y study period at Keji, however, spatial trends were generally similar between sites. Seasonal trends were observed with peak deposition generally occurring during the growing period (spring-summer) for the HCHs, chlorothalonil, endosulfan, and atrazine. Bimodal seasonal trends were also observed for these compounds with the exception of endosulfan.     

Water Planning and Hydro-Climatic Change in the Murray-Darling Basin,Australia

More than a third of humanity lives in regions with less than 1 million liters of fresh water per person per year. Population growth will increase water demand while climate change in arid and semi-arid areas may reduce water availability. The Murray-Darling Basin in Australia is a region where water reform and planning have been used to reduce consumptive extraction to better sustain river ecosystems under climate variability. Using actual data and previously published models that account for climate variability and climate change, the trade-off between water extractions and water essential to the long-term ecological function of river systems is analysed. The findings indicate that better water planning and a more complete understanding of the effects of irrigation on regional climate evapotranspiration could: (1) increase the overall benefits of consumptive and non-consumptive water use; (2) improve riparian environments under climate variability; and (3) be achieved with only small effects on the profits and gross value of food and fiber production.     

Mean Drop Size in a Full Scale Venturi Scrubber via Transmissometer

This paper describes the construction of and the data obtained from a light transmissometer capable of making mean drop size measurements within about ±15%. The experimental venturi had a throat flow cross-section of 12 in. by 14 in. and overall length in the flow direction was 15 ft. It was found that the Nukiyama-Tanasawa equation gave accurate estimates of Sauter mean drop size only for a throat velocity of 150 ft/sec.     

Automated detection of frog calls and choruses by pulse repetition rate

Anurans (frogs and toads) are among the most globally threatened taxonomic groups. Successful conservation of anurans will rely on improved data on the status and changes in local populations, particularly for rare and threatened species. Automated sensors, such as acoustic recorders, have the potential to provide such data by massively increasing the spatial and temporal scale of population sampling efforts. Analyzing such data sets will require robust and efficient tools that can automatically identify the presence of a species in audio recordings. Like bats and birds, many anuran species produce distinct vocalizations that can be captured by autonomous acoustic recorders and represent excellent candidates for automated recognition. However, in contrast to birds and bats, effective automated acoustic recognition tools for anurans are not yet widely available. An effective automated call-recognition method for anurans must be robust to the challenges of real-world field data and should not require extensive labeled data sets. We devised a vocalization identification tool that classifies anuran vocalizations in audio recordings based on their periodic structure: the repeat interval-based bioacoustic identification tool (RIBBIT). We applied RIBBIT to field recordings to study the boreal chorus frog (Pseudacris maculata) of temperate North American grasslands and the critically endangered variable harlequin frog (Atelopus varius) of tropical Central American rainforests. The tool accurately identified boreal chorus frogs, even when they vocalized in heavily overlapping choruses and identified variable harlequin frog vocalizations at a field site where it had been very rarely encountered in visual surveys. Using a few simple parameters, RIBBIT can detect any vocalization with a periodic structure, including those of many anurans, insects, birds, and mammals. We provide open-source implementations of RIBBIT in Python and R to support its use for other taxa and communities.     

Fluorescence characterization of cross flow ultrafiltration derived freshwater colloidal and dissolved organic matter

3-D fluorescence excitation-emission matrix (EEM) spectrophotometry was applied to investigate the fluorescence characterization of colloidal organic matter (COM) and truly dissolved organic matter (DOM) from an urban lake and a rural river fractionated by the cross flow ultrafiltration (CFUF) process with a 1kDa membrane. Relatively high tryptophan-like fluorescence intensity is found in the urban water, although the fluorescence of both water samples is mainly dominated by humic/fulvic-like fluorophores. During CFUF processing, the fluorescence intensities of humic/fulvic-like materials in the retentate increased rapidly, but a slight increase is also observed in the permeate fluorescence intensity. Very different ultrafiltration behaviour occurred with respect to the tryptophan-like fluorophore, where both permeate and retentate fluorescence intensities increase substantially at the beginning of the CFUF process, then tend to remain constant at high concentration factor (cf) values. Comparison with tryptophan standards demonstrates that freshwater tryptophan-like fluorescence is not dissolved and 'free', but is, in part, colloidal and related to the ultrafiltration behaviour of fulvic/humic-like matter. A good linear relationship between the retentate humic/fulvic-like fluorescence intensity and organic carbon concentration further reveals that fluorescent humic/fulvic-like substances are the dominant contributors to colloidal organic carbon, mainly in the colloidal fraction.     

Atmospheric Chemistry of Chlorinated Phenols

The quantum yields for the photodegradation of a series of chlorophenols have been used to estimate their rates of solar photodegradation In the atmosphere. The photochemical rates have been compared with the calculated rates of attack by atmospheric hydroxyl radicals. These two processes are complementary, with photolysis being faster for pentachlorophenol, and OH attack being faster for monochlorinated phenols. As a result, it is predicted that most chlorophenol congeners will have quite similar atmospheric half-lives.     

Impact of microbial activity on copper, lead and nickel mobilization during the bioremediation of soil PAHs

A fungal bioremediation method using P. frequentans removed up to 75% of phenanthrene with the addition of water and nutrients over a period of 30 d. During the bioremediation process, changes in metal behavior were monitored by an in situ technique (diffusive gradients in thin-films, DGT) and by soil solution chemistry. DGT provided absolute data on fluxes from the solid phase to the DGT device and relative trends of concentrations of the most labile metal species. DGT response indicated that bioremediation increases metal mobilization from the solid phase. Filtration provided data on the concentrations of solution phase (<0.45 microm) metal. In all case, metal fluxes and concentrations significantly increased after the bioremediation process began. Fluxes increased from <0.1 pg cm(-2)s(-1) before bioremediation to between 0.2 and 0.5 pg cm(-2)s(-1) after bioremediation. Metal concentrations in the soils solution (filtration at 0.45 microm) increased from 2 to 10 microg l(-1) (Cu), 1-4 microgl(-1) (Pb) and from 40 to 140 microg l(-1) (Ni) after bioremediation. Although over a short time period, these data strongly indicated that there was remobilization of metal from solid to solution (and thus to the DGT device) directly due to the bioremediation process. Although the mechanism was not unambiguously identified, it was shown not to be related to small changes in bulk pH over time and was attributed to the microbial action on the surface of the soil solid phase, releasing metal into solution. Additionally, differences in metal concentration and flux were observed in sterilized and non-sterilized soils and in the absence or presence of phenanthrene. The results indicated that the bioremediation of soil by P. frequentans increased the flux, lability and mobility of trace metal species and therefore the likely metal bioavailability to plants.     

Community-based participatory research: Changing scientific practice from research on communities to research with and for communities

This paper examines community based participatory research from the viewpoint of the author, a doctoral student seeking to understand the concepts and framework of successful participatory research as a complement to traditional discipline driven research. Challenges and progress of CBPR within academia are examined, including acceptance, funding, training, and development of equal partnerships between university researchers and communities. Case studies (Latowsky, 2003; Ammerman et al., 2003; Stratford et al., 2003) focus on CBPR in different environmental justice communities, revealing the need to foster trust and communication in order to execute culturally competent and relevant research projects.     

A Hydraulic MultiModel Ensemble Framework for Visualizing Flood Inundation Uncertainty

While deterministic forecasts provide a single realization of potential inundation, the inherent uncertainty associated with forecasts also needs to be conveyed for improved decision support. The objective of this study was to develop an ensemble framework for the quantification and visualization of uncertainty associated with flood inundation forecast maps. An 11‐member ensemble streamflow forecast at lead times from 0 to 48 hr was used to force two hydraulic models to produce a multimodel ensemble. The hydraulic models used are (1) the International River Interface Cooperative along with Flow and Sediment Transport with Morphological Evolution of Channels solver and (2) the two‐dimensional Hydrologic Engineering Center‐River Analysis System. Uncertainty was quantified and augmented onto flood inundation maps by calculating statistical spread among the ensemble members. For visualization, a series of probability flood maps conveying the uncertainty in forecasted water extent, water depth, and flow velocity was disseminated through a web‐based decision support tool. The results from this study offer a framework for quantifying and visualizing model uncertainty in forecasted flood inundation maps.