Abomasal size and emptying time in healthy lambs and in lambs affected by watery mouth

Contrast radiography (barium sulphate suspension fed by stomach tube) was used to assess abomasal profile area (a reflection of tone in the abomasal wall) and the rate of abomasal emptying in healthy lambs aged four to 144 hours and in lambs affected by watery mouth. In healthy lambs abomasal profile area increased from 15.1 +/- 0.56 cm2/kg at four hours of age to 23.1 +/- 1.07 cm2/kg at 24 to 48 hours (P less than 0.001). There was no change up to 48 to 72 hours but after this age there was a substantial decrease to 12.8 +/- 0.76 cm2/kg at 120 to 144 hours (P less than 0.001). The rate of abomasal emptying decreased as abomasal profile area increased. Complete emptying of the abomasum was observed within three hours of feeding in the majority of lambs aged four hours (seven out of eight) and 120 to 144 hours (13 out of 16) but only in a minority of lambs aged 24 to 48 hours (one out of 11). In lambs affected by watery mouth (mean age [+/- se] 33 +/- 2.8 hours, n = 34) abomasal profile area was greater and the rate of abomasal emptying was slower than in healthy lambs aged 24 to 48 hours. These findings confirm the previous suspicion that watery mouth is associated with an impairment of gut motility. Abomasal emptying time was prolonged in lambs aged four hours when either ewe or cow colostrum was included with the contrast medium. A similar effect was observed in lambs aged 24 to 48 hours when cow colostrum was included. The castration of lambs aged four hours with rubber rings immediately before the administration of contrast medium had no effect on the rate of abomasal emptying.     

The impact of gas extraction on landfill-generated methane gas levels

The changes measured in landfill-generated CH₄ gas levels in response to continuous pumping from an augered borehole in the refuse are described. The results of statistical analyses of concentration and pressure levels at a series of probes located radially outward from the gas extraction well are used to characterize the temporal and spatial variations. A drawdown curve arising from the continuous pumping is apparent and is quantified as a series of cones of varying impacts on percentages of CH₄. The results are indicative of a fairly free flow of gas through the landfill.     

highway stormwater runoff quality: development of surrogate parameter relationships

The development of relationships for predicting the impact of highway stormwater runoff is described. The predictive relationships are regression-based equations reflecting variations in the magnitude of the constituents of interest. The objective is to identify a subset of constituents that can be used as surrogates for the remaining constituents as a means of decreasing the costs of collection and measurement of highway stormwater runoff quality data. The Minnesota highway stormwater quality database complied in the late 1970's and early 1980's is employed in identifying the set of surrogate parameters. The findings indicate that total suspended solids, total dissolved solids, total volatile solids, and total organic carbon are effective surrogate parameters for numerous metals, ionic species, and nutrients. The findings also indicated that the developed ionic species constituent relationships are portable, while the metal and nutrient constituent relationships were limited to urban sites with similar environmental conditions. The development of these relationships represents a step towards remediating and preventing the problem of nonpoint source highway pollution.     

Quality tests of potato varieties in Australia

Color, texture and flavor were scored and specific gravity and dry matter contents were determined over a 13-year period on 262 varietal samples of potatoes grown in Australia. Statistical analyses of these results showed highly significant differences in each of the three culinary factors, just significant differences in dry matter content and no significant differences in specific gravity. There was a close linear relationship between dry matter content and specific gravity but the latter was shown to be an unreliable index of culinary quality. A pronounced mutual agreement which existed amongst the three culinary factors suggests that a reliable objective method for any of them would be an advantage in early screening tests of newly developed varieties.     

Linear programming for abatement of nitrogen oxides acid rain deposition

Linear programming is used to examine NO_x as an air quality management problem. Through the use of transfer coefficients, which translate source emissions of NO_x into receptor impacts, the model developed herein seeks to minimize the total cost of reducing emissions from 14 major Canadian point sources. It does this subject to the constraint that the wet deposition at 5 sensitive receptors must be reduced by at least some minimum amount. Several different reductions in wet deposition are used to observe the increase in costs associated with a systematic ‘tightening’ of the constraint relationships. A particular level of reduction is used to examine, on a more detailed level, the sources requiring some level of removal. These case study results and an analysis of the rationale for their solution are presented. Also presented is a comparison between this type of optimization strategy and the scenario of a single ‘across-the-board’ emissions cutback. From NO_x considerations alone, it would seem more expedient to concentrate current research efforts into developing technologies to further reduce vehicle emissions, since their magnitude considerably outweighs those from the point sources.     

Nonlinear optimization modeling of coliform bacteria

An optimization model for use in the planning stage of the water quality management process was developed. The model determined the optimal removal of coliform bacteria in accordance with an objective function which reflects the uncertainty aspects of the problem. Several management options are available through model use thereby providing a decision-maker with considerable latitude to evaluate the relative importance of the conflicting objectives of the problem.     

Water Quality Modeling of the Kali River,India

Water quality monitoring procedures effective in calibrating the QUAL2E model for the Kali River in India are described. The stability of dry season conditions for the Kali River are utilized to consider the migration pathways, and hence the calibration efforts necessary for water quality models. Alternative procedures for calibrating values for the reaction rates are utilized for reinforcement of the findings. These alternatives include changes in stream turbidity which are shown to be a useful measure of benthic oxygen demand. Ratios of BOD₅ to COD are reported between sugar mills, industrial inputs and municipal sources.     

Incorporation of wind roses in a statistical long-range pollution transport model

A modified version of the Ontario Ministry of the Environment Statistical Long-Range Transport (LRT) Model has been developed at the University of Waterloo. The model incorporates wind rose data at pollutant sources and receptors to reflect the percent of time that a source pollutant plume is affecting a down-wind receptor. Comparison of output to results generated by complex LRT models (i.e., the AES and MOE Lagrangian models) has demonstrated that the modified model results replicate complex model results fairly well. However, the model presented preserves the advantages of low execution costs and simple data input. This benefit permits the user to efficiently simulate a large number of LRT scenarios.     

An examination of temporal/spatial variations in landfill-generated methane gas

The experimental findings of a data-intensive in situ landfill monitoring study are described. Particular attention is given to the methodology employed in collecting the data, analyses of the spatial/ temporal variability of the gas percentages, by volume and the extent to which the variability in collected results is explained by variations in exogenous independent variables. Measurable gas flow rates from the soil could not be detected through the probe system employed in the field study.     

Influence assessment of landfill gas pumping

Changes in CH₄ gas concentrations arising in a landfill as a consequence of a number of gas extraction pumping rates, are characterized. The field-monitored results indicate a fairly free flow of gas through the refuse. High pumping rates impact large expanses of the landfill site and may deplete the CH₄ levels in the surface regions of the refuse.