Field demonstration of visible opacity photographic systems

The Digital Opacity Compliance System (DOCS) is an innovative method that uses digital imaging technology to quantify visible opacity of stationary sources. DOCS, which has been demonstrated at pilot and full scale as a technically defensible and economically attractive alternative to U.S. Environmental Protection Agency (EPA) Reference Method 9 (Method 9), uses commercial-off-the-shelf (COTS) digital cameras in combination with a user-friendly computer software package to determine opacity. To date, all DOCS field testing has been conducted using two models of digital cameras, notably, Kodak Models DC265 and DC290, both of which are no longer commercially available. To ensure that field-validated digital cameras will be available to future DOCS users, a suite of new digital cameras was evaluated with the opacity determination software including the following: (1) Sony Model Cybershot Model DSC-WI, (2) Nikon Model Coolpix 5200, (3) Fuji Finepix Model E500, and (4) Kodak Model DX6490. Within the opacity range of regulatory interest, that is, 0-40%, the Sony Cybershot Model DSC-WI and Nikon Coolpix Model 5200 digital cameras were found to generate plume photographs of which the DOCS opacity analysis yielded results that were statistically equivalent to the previously field-validated Kodak Model DC290. In contrast, the Fuji Finepix Model E500 generated plume photographs of which the DOCS opacity analysis were, on average, 2.2% less than those generated by the Kodak Model DC290 photographs, a difference that was determined to be statistically significant. Over the same opacity range, photographs taken by the Kodak Model DX6490 yielded DOCS opacity readings that were found to be statistically equivalent to a Method 9-certified transmissometer. Based on the results from the current digital camera validation testing approach, EPA has developed a new camera-based visible opacity measurement method titled "Determination of Visible Emission Opacity from Stationary Sources Using Computer-Based Photographic Analysis Systems." The proposed method is expected to be promulgated after closure of the public comment period.     

In pursuit of proper contexts for sustainability in rural Africa

Summary Sustainable development is high on development analysts' agendas as people seek viable alternatives to current development concepts. These latter approaches have not satisfied people's livelihoods especially in developing countries. This paper suggests that the promotion of sustainable development must correctly identify the contexts within which it is to be pursued. It is essential to note that this is best done if people recognize that as a complex concept, sustainable development has several dimensions, including the resource base of a country/community/society; external factors impacting on it; internal factors at play within; population factors and political economic factors.For rural Africa, the context is one of small community and kinship based production groups largely dependent on their local environments for survival. It is essential to identify endogenous factors such as local knowledge bases, common property arrangements, other local social institutions and local environmental practices and to base sustainability strategies on these.There is growing awareness of the efficacy of these local indigenous systems but constraints to their promotion as a valuable resource are also significant. There is room for being hopeful that rural Africa might sustain itself if recognition of the correct contexts is sought.Mr Joseph Z.Z. Matowanyika obtained his Bachelor's and Master's Degrees respectively at the Universities of Reading and Nottingham, in the UK. He is currently undertaking research in the Department of Geography of the University of Waterloo for a Doctor of Philosophy.     

Effects of nest site concealment on hatching success,reproductive success,and paternal behavior of the threespine stickleback,Gasterosteus aculeatus

Summary Male sticklebacks (Gasterosteus aculeatus) actively competed for a limited number of clay flowerpots as nest sites in circular wading pools. Males nesting in pots spawned earlier and more often, had higher mean and lower variance for hatching success (number of fry per gram of estimated clutch weight), and suffered fewer stolen fertilizations, nest raids, and territorial encounters than did males nesting outside pots, and in pools without pots (Table 2). Males nesting in pots had the more even temporal distribution of fanning bouts and interfanning intervals; the durations of fanning bouts and interfanning intervals were less variable for these males (Table 2).In replicate aquaria, one male nested on each side of a glass partition and both males spawned approximately simultaneously. Flowerpots were provided to one, both, or neither male. Males with pots had higher mean hatching success, fewer territorial encounters, and the more even temporal distribution of fanning bouts and interfanning intervals (Table 4).Thus it appears that nest site concealment, in the form of clay flowerpots, affected male hatching success, reproductive success, and parental behavior, even when physical contact between males was prevented. These data suggest that a causal relationship may exist between the paternal fanning regime and the subsequent hatching success. Furthermore, these data suggest that males which nest in high concealment increase their reproductive success, and that females which spawn with these males reduce the variance of their hatching success as well as increase their mean hatching success.     

Formation of pi-pi complexes between phenanthrene and model pi-acceptor humic subunits

Pi-pi interactions may play a role in association of aromatic compounds with natural organic substances. Complexation in aqueous solvents was studied between the pi donor, phenanthrene (PHEN), and model pi-acceptor species (quinones and N-heteroaromatic cations) that represent certain functional units of humic substances. Charge-transfer bands in the UV and ring-current shifts in the proton nuclear magnetic resonance (NMR) spectrum confirmed the face-to-face, pi-pi donor-acceptor nature of the bond. Complexation constants were obtained by the solubility enhancement method; solubility enhancements up to 2500 were found. Ruled out as predominant causes of solubility enhancement were monomer desolvation (i.e., "hydrophobic" effects), partitioning into micelles, pi-cation interactions, and pi-hydrogen bonding. Acceptor self-stacking and formation of higher-stoichiometry acceptor-donor complexes had to be considered in evaluating donor-acceptor equilibria in some cases. The affinity of acceptor for PHEN followed the order of increasing pi-acceptor strength and varied strongly with the degree of ring overlap with PHEN. Complexation between PHEN and the free solution faces of an acceptor was less favorable than intercalation of PHEN between two acceptor units in a stack. A positive hydrophobic effect on complexation was evident in water mixtures with acetone or methanol and found to correlate with the number of faces of PHEN requiring desolvation to form the complex. When hydrophobic effects are subtracted out, the pi-pi complex actually becomes favored as the solvent water content and polarity decline. The results suggest that phenanthrene, and by implication other donor aromatic compounds, are capable of forming pi-pi interactions with appropriate humic fragments.     

Solid-state carbon-13 nuclear magnetic resonance of humic acids at high magnetic field strengths

Use of solid-state 13C nuclear magnetic resonance (NMR) spectroscopy has become commonplace in studies of humic substances in soils and sediments, but when modern high-field spectrometers are employed, care must be taken to ensure that the data obtained accurately reflect the chemical composition of these complex materials in environmental systems. In an effort to evaluate the quality of solid-state 13C NMR spectra obtained with modern high-field spectrometers, we conducted a series of experiments to examine spectra of various humic acids taken under a variety of conditions. We evaluate conditions for obtaining semiquantitative cross polarization magic angle spinning (CPMAS) 13C NMR spectra of humic acids at high magnetic field and spinning frequency. We examine the cross polarization (CP) dynamics under both traditional and ramp CP conditions on Cedar Creek humic acid. Fitted equilibrium intensities from these CP dynamic studies compare to within 3.4% of the intensities determined from a Bloch decay spectrum of the same sample. With a 1-ms contact time, ramp CP and traditional CP spectra were acquired on this sample and were found to compare to within 5.4% of the Bloch decay spectrum; however, the signal-to-noise ratio per hour of data acquisition was found to double under ramp CP conditions. These results demonstrate the power of applying modern solid-state NMR techniques at high magnetic field strengths. With these techniques, high-quality, semiquantitative spectra can be quickly produced, allowing the application of solid-state NMR techniques to more environmentally relevant samples, especially those where the quantity is limited.