Influence of source characteristics, chemicals, and flocculation on chemically enhanced primary treatment.

The overall objective of this research was to investigate various methods and parameters to increase the efficiency of chemically enhanced primary treatment (CEPT). The performance of CEPT was evaluated based on its efficiency of removal of nonsettleable solids (NSS). Some of the source characteristics that influenced NSS concentration included influent total suspended solids, influent turbidity, and influent total chemical oxygen demand. A higher concentration of the influent constituents led to a higher NSS concentration, suggesting that NSS represented a somewhat fixed fraction or percent of these influent constituents. The specific particle surface area (SPSA) was found to correlate with percent NSS in the effluent. A higher SPSA is a result of smaller-sized nonsettleable colloidal particles, thus leading to an increase in percent NSS. In summary, there are several parameters that affect NSS, which could be used to control NSS to improve CEPT, as demonstrated by this study.     

Between-caste aversion as a basis for division of labor in the ant Pheidole pubiventris (Hymenoptera: Formicidae)

Summary When deprived of minor workers under expermental conditions, major workers of the ant Pheidble pubiventris dramatically increase their repertory and rate of activity, and the change is due in good part to the greater attention they pay the brood. When minor workers are reinstated in appropriate numbers, the majors reduce their attention to the immature stages to the ordinary, low levels. Their response consists of the active avoidance of minors while in the vicinity of the immature stages. However, majors do not turn from other majors near the brood as much as they do from the minors, and they do not avoid minors at all while in other parts of the nest. In addition, minors do not avoid either minors or majors anywhere in the nest. The result is a striking division of labor with reference to brood care.     

Effect of the trichothecene deoxynivalenol on brain biogenic monoamines concentrations in rats and chickens

Male Sprague-Dawley rats (180 g) and 28-day-old Single Comb White Leghorn Cockerels (300 g) were orally dosed with deoxynivalenol (DON) at 2.5 mg kg-1 body weight. In the first experiment, whole brains were collected at 2, 6, 12, 24 and 48 hours after the toxin treatment and analyzed for brain biogenic monoamines by high-performance liquid chromatography with electrochemical detection. Although several interesting trends were observed, DON did not influence whole brain concentrations of monoamine neurotransmitters or their metabolites in either species, at any time. In a second experiment, brains were collected 24 hours postdosing, dissected into 5 brain regions (pons and medulla oblongata, cerebellum, hypothalamus, hippocampus and cerebral cortex), and analyzed. DON treatment resulted in significantly elevated concentrations of serotonin (HT) and 5-hydroxyindole-3-acetic acid (HIAA) in all brain regions of the rat. However, this was not seen in poultry, where DON treatment resulted in a decrease in norepinephrine (NE) in the hypothalamus and hippocampus, and a decrease in dopamine (DA) in the pons and medulla oblongata region. These results suggest that DON influences brain biogenic amine metabolism, and that there may be intraspecies differences in the central effects of this mycotoxin.     

The valuation of wetland conservation in an urban/peri urban watershed

This study estimates the social benefits of wetland conservation in the Credit River watershed, located in an urban/peri urban area in Southern Ontario, Canada. A stated preference approach was employed to value wetland conservation programs which ranged from retaining the existing wetlands to restoring various levels of acres of wetlands over the 2009–2020 period. A total of 1,407 households completed an internet-based survey which presented trade-offs in binary choice scenarios framed as referenda. Responses were analyzed using various models, one of which was a latent class analysis which segmented respondents into three classes. This econometric approach uncovered significant preference heterogeneity for wetland conservation. Assignment of respondents to the classes suggested that about one-third of the sample was willing to pay small amounts to retain the existing wetlands. An additional third was willing to pay several hundred dollars a year for retention and small positive amounts for additional restoration. The final third were apparently willing to pay considerable sums for retention, but lesser amounts for additional restoration. However, further analysis revealed that respondents in this third class largely constituted yea-sayers. These results suggest caution in interpreting associated economic valuation estimates and highlight the importance of attempting to understand hypothetical bias in wetland and other such valuation studies.     

Research and development to improve naval shipboard waste management using a compact closed-loop-controlled waste incinerator

Research has been conducted into the application of forced acoustics for enhancing the performance of a pyrolyzed waste afterburner configured as a dump combustor. Subscale studies showed that acoustic forcing of an air jet entering a dump chamber could trigger the formation of coherent vortices generated by entrainment of ambient gases. Subsequent studies showed that combustible gases could be introduced into the coherent vortices, and with additional modulation this configuration would lead to an enhanced combustion rate with low emissions of pollutants. The acoustically forced burner concept was scaled up to practical levels and tested as an afterburner on a commercial waste incinerator operating in pyrolysis mode. Results show that the afterburner can promote both compactness, due to the rapid combustion rate, and low pollutant emissions resulting from enhanced mixing prior to combustion.     

Migration of pollutants in groundwater. II. adsorbable pollutants and numerical dispersion reduction

We discuss here the partial differential equations governing the migration of a decomposing pollutant adsorbing according to a Langmuir isotherm and undergoing 2-dimensional flow in a saturated aquifer. The equation governing the mass transfer of the pollutant to the surfaces within the aquifer are solved in closed form, permitting the use of larger values of the time increment t in the numerical integration of the dispersion-advection equation governing the behavior of the dissolved pollutant. In this numerical integration transverse numerical dispersion is eliminated by using conformal coordinates (velocity potential and stream function), and longitudinal numerical dispersion is very substantially reduced by use of an asymmetrical 4-point formula to represent the advection term. Some representative results are given as contour maps. The mass transfer rate coefficient is estimated as the least positive eigenvalue of a diffusion problem.     

Organochlorine contaminants in Caspian and harbour seal blubber

Organochlorine contaminants (pesticides and individual polychlorinated biphenyl congeners, PCBs) were measured in Caspian (Phoca caspica) seal blubber and compared with concentrations in Harbour (Phoca vitulina) seal blubber. Concentrations of total dichlorodiphenyltrichloroethane (DDT) and its metabolites were significantly higher in Caspian seal than Harbour seal samples, whereas PCB congeners were significantly higher in Harbour than Caspian seals. Our finding suggests that Caspian seals are exposed to high levels of DDT pesticides. In contrast, PCBs are circulating in this population at much lower levels than in marine mammals from the North Sea.     

Life-history evidence for sibling species in Axiothella rubrocincta (Polychaeta: Maldanidae)

Individual Axiothella rubrocincta Johnson on the Californian coast live in U-shaped tubes, feed on the surface of the sediment, attain densities of 100 m^-2, attain lengths of 140 mm, have maximum oocyte diameters of 220 μm and produce demersal larvae. Individuals from Washington populations live in vertical tubes, feed 10–15 cm below the sediment surface, reach densities of 5000 m^-2, attain lengths of 60 mm, have maximum oocyte diameters of 385 μm and brood their young in their tubes to at least the 7-setiger stage. Individuals from California have a scalloped posterior margin of the cephalic plate, while individuals from Washington have entire margins. There are no other consistent morphological differences between populations. The population from Eagle Cove, Washington has individuals similar in size and oocyte diameter to individuals from California, but which maintain vertical tubes. A. rubrocincta represents a sibling species complex.