The Cataraqui River, which drains 930 square km of watershed before emptying into the inner harbour of Kingston, Ontario (pop: 113,000), has a long history of anthropogenic use. More than 40 industries have existed within the inner harbour over the last century, and while many of these industries are no longer present, the properties that they operated on remain to the present day as potential sources of persistent contamination. This study examined total mercury (THg) concentrations in depth profiles of 21 sediment cores within the inner harbour. THg in pore waters was measured in some selected cores along with methylmercury (MeHg), and total organic carbon measured as % Organic Matter (OM). Results show that the spatial distribution of THg in the surface sediment is not homogenous; concentrations in surface sediment along the southwestern shoreline, adjacent to the former industrial properties, are significantly greater than the rest of the inner harbour, and above the severe effect limit (2000 μg/kg) guideline for sediment. MeHg was detected in some sediment cores, and was found to have a significant, positive correlation with [THg] in surface sediment. THg in pore water was below detection limits in most cores, indicating possible strong associations with sediments, however OM only showed significant, positive correlations with THg in one core sampled. To determine the sources of Hg to sediments, soils, runoff and storm sewer discharges near high concentration sediments were measured for THg. Hg was not detected in storm sewers, but was detected in terrestrial soil near the Kingston Rowing Club at a concentration of more than 4000 μg/kg. Significant [THg] was detected in runoff draining shoreline soils, indicating that erosion from terrestrial sources may be an ongoing source of Hg to sediment. Since [THg] was correlated to the [MeHg] in surface sediment, reducing the amount of Hg entering the river from terrestrial sources may reduce the amount of bioavailable Hg in sediments of the inner harbour. / Thesis (Master, Biology) -- Queen's University, 2007-11-01 19:12:24.364

<p>Listeria monocytogenes is a Gram-positive bacterium responsible for listeriosis, a food-borne disease, which may result in severe illness and possible death. The importance of L. monocytogenes as a food-borne pathogen has been recognized since the 1980's when a correlation between the cunsumption of contaminated foodstuffs and human listeriosis outbreaks was observed. Listeriosis occurs with the ingestion of contaminated foods. The aim of this study involved developing DNA based methods to aid the food industry for the fast detection of L. monocytogenes in food products. Therefore assays were developed in such a way that they will have potential applications in the food idustry.</p>

The fluorodinitrobenzene (FONB), succinic anhydride (SA), dansyl chloride (DAN), dye-binding lysine (OBL), total lysine (TL), ninhydrin (NIN) and Tetrahymena lysine (TET) methods were compared for their ability to assess available lysine in soyaprotein heated in the absence or presence of glucose, lactose or xylose and in formaldehyde-treated lactalbumin. The reactive lysine methods showed comparable sensitivity to lysine damage in soyaprotein heated in the absence of sugar, the results indicating the presence of acid labile isopeptides and unidentified acid stable derivatives. Results for soyaprotein heated with glucose, lactose or xylose showed that the type of sugar and the extent of heat treatment has a strong influence on the progress of the Maillard reaction. Furthermore since fructoselysine (F-L) and lactulosyl-lysine (L-L) are colourless up to 30% loss of available lysine can occur without any change in product colour. The FONB method is the most sensitive for mildly damaged glucose-soya samples followed by DAN or OBL, SA and TL whereas for mildly damaged lactose-soya samples the order is OBL, FONB, SA, TL and DAN. For severely damaged samples the DAN or SA methods were the most sensitive followed by OBL, FONB and TL. Formylation of lactalbumin occurred more readily at higher formaldehyde concentrations. Exposure time had less effect while pH (5 and 9) had no effect. Methylene derivatives reached maximum levels sooner than the methylol compounds. Lysine and tyrosine but not histidine formed methylene bridges while tyrosine was found to condense with free formaldehyde during acid hydrolysis raising questions as to the interpretation of similar studies reported in the literature. The FONB, OBL and DAN methods were all very sensitive to this type of damage with the NIN and TL methods being less sensitive and the SA method being completely unsuitable. The TET assay is unsuitable for 'early' Maillard damage since at low sample-N levels growth is stimulated by its ability to utilise unavailable F-L and L-L while at higher N-levels growth is inhibited. No single method is most suitable for all types of damage. Furthermore, all except DAN and DBL are either too long, rather complicated, require expensive equipment or involve the use of dangerous chemicals. The DAN method appears promising but the problem of converting arbitrary fluorescence units to lysine values needs to be overcome. The DBL is recommended for routine analysis since it is simple, economical and highly sensitive to all lysine damage provided care is taken to optimise dye-binding for each type of material analysed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1985.

Seabed environmental monitoring programmes have been conducted at oil installations in the North Sea for many years. Such studies seek to determine the areal extent of the spread of contaminated cuttings and effects on assemblages of benthic organisms. Survey programmes usually follow a prescriptive programme with respect to the numbers of samples, mesh size and level of taxonomic identification. This thesis examines the effects of altering these survey components on the information content of three commonly used ordination methods, PCA, DCA and CA, with the aim of determining the minimum necessary expenditure to show the same outputs. The use of microbial bioassays was investigated as a potential alternative means of assessing the extent of infaunal disturbance. <I>Minimum number of replicates</I>. When analysing data from a strong environmental gradient, one replicate sample per station provided the same visual information as the total data set of two replicates. The DCA and CA procedures provided outputs which were easily interpretable ecologically, but the PCA biplots were difficult to interpret. Analysis of data from a weak environmental gradient required a higher number of replicates for each technique and outputs were more variable at low replicate numbers. <I>Taxonomic resolution</I>. When infauna were aggregated to the taxonomic level of class, the information content of the three ordination methods was the same as recorded for species level. However, at the taxonomic levels of order and phylum the information on the bi-plots was difficult to interpret. Although this suggests that there exists the potential for reducing the cost of analysis, further corroboration with different data sets would be required. <I>Sieve size</I>. Primary screening of 0.5 mm mesh fauna by a 1.0 mm mesh may be a more cost effective strategy than either a 1.0 mm or 0.5 mm fraction although there was some loss of information on the ordination bi-plots.

This thesis describes the results of three studies that used different measures of bacterial numbers in retail ground beef (n=309) collected across different locations in Saskatchewan within a one-year period (May 2011 – May 2012). The measurements were compared among three sample categories: 1 - ground beef displaying government inspection information on the label legend (n=126), 2 - originating from facilities licensed by local health regions and thus not subjected to government inspection (n=80), or 3 - processed and repackaged at the retail level thus carrying no government inspection information on the label (n=103). The first study reports baseline levels of bacteria in Saskatchewan retail ground beef as measured by traditional (total aerobic plate count (TAPC) and total E. coli plate count (TEPC)) and culture-independent methods (estimate of total bacterial load (TBL) by real-time quantitative polymerase chain reaction). After accounting for season and whether the samples were fresh or frozen at purchase, the lowest TAPC (log10 4.9 culture forming units per gram (cfu/g); 95% CI log10 4.7 to log10 5.1 cfu/g), TEPC (log10 0.58 cfu/g; 95% CI log10 0.39 to log10 0.77 cfu/g), and TBL in frozen ground beef (log10 4.5 target copies per gram (tc/g); 95% CI log10 4.0 to log10 4.9 tc/g) were observed in samples originating from federally regulated or provincially licensed facilities. In the second study, presence of known Enterobacteriaceae virulence factors (stx1, stx2, and eae) was detected by polymerase chain reaction (PCR) and compared between samples originating from three different regulatory and inspection environments as well as collected during different seasons of the year, and purchased fresh or frozen. One hundred and twelve out of all tested samples (n=308) were positive for the presence of at least one virulence marker with stx1 identified in 107 samples, stx2 - in 8, and eae - in 26. No significant associations were found between the virulence markers presence and sample category, state or season of purchase. The third study investigates the presence and diversity of Campylobacter spp. organisms in the same pool of 309 retail beef samples as detected by molecular methods. Fifty samples (16.2%) tested positive for Campylobacter genus-specific DNA in conventional PCR and 49 samples (15.9%) tested positive for at least one Campylobacter species DNA presence in real-time qPCR, but the crude agreement between the two methods was less than 50%. C. coli DNA presence was observed in 14 samples (4.5%), C. curvus – in 11 (3.6%), C. fetus – in 6 (1.9%), C. hyointestinalis – in 24 (7.8%), C. jejuni – in 12 (3.9%), C. rectus – in 6 (1.9%), and C. upsaliensis – in 9 (2.9%). There was no difference in the frequency of Campylobacter identified among the three sample categories, fresh and frozen, or samples purchased during the cold or warm season. These studies provide data on prevalence of bacteria in retail ground beef offered for sale in Saskatchewan and compare differences between samples presented to the consumer as originating from federally regulated or provincially licensed facilities, locally licensed facilities, or repackaged and processed directly at a retail outlet. The information on baseline levels of bacteria in retail ground beef and the comparisons among different categories can be used in prioritising food safety improvement efforts in Saskatchewan.

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No description available.

The aim of the present work was to investigate aflatoxin levels in various food commodities and to study its production by Aspergillus parasiticus in culture to find out the possible ways to control it. Of 40 food samples collected from Abha region, Saudi Arabia, only 25% were contaminated with aflatoxins. Oil-rich commodities had the highly contaminated commodities by fungi and aflatoxins while spices were free from afatoxins. The optimal pH for the growth of A. parasiticus and its productivity of aflatoxin B, was found at 6.0, while the best incubation conditions were found at 30°C for 10 days. D-glucose was the best carbon source for fungal growth, as well as aflatoxin production. Corn steep liquor, yeast extract and peptone were the best nitrogen sources for both fungal growth and toxin production. (NH4)2HPO4 (1.55 gL-1) and NaNO2 (1.6 gL-1) reduced fungal growth and toxin production with 37.7% and 85%, respectively. Of ten amino acids tested, asparagine was the best for aflatoxin B, production. Zn2+ and Co2+ supported significantly both fungal growth, as well as aflatoxin B, production at the different tested concentrations. Zn2+ was effective when added to A. parasiticus growth medium at the first two days of the culture age. The other tested metal ions gave variable effects depending on the type of ion and its concentration. Water activity (a ) was an important factor controlling the growth of A. parasiticus and toxin production. The minimum aW for the fungal growth was 0.8 on both coffee beans and rice grains, while aW, of 0.70 caused complete inhibition for the growth and aflatoxin B, production. H202 is a potent inhibitor for growth of A. parasiticus and its productivity of toxins. Incubation with NaHCO3 and C6H5000Na converted aflatoxin B, to a water-soluble form which returned to aflatoxin B, by acid treatment. Black pepper, ciliated heath, cuminum and curcuma were the most inhibitory spices on toxin production. Glutathione, quinine, EDTA, sodium azide, indole acetic acid, 2,4-dichlorophenoxy acetic acid, phenol and catechol were inhibitory for both growth, as well as, aflatoxin B, production. Stearic acid supported the fungal growth and decreased the productivity of AFBI gradually. Lauric acid is the most suppressive fatty acid for both fungal growth and aflatoxin production, but oleic acid was the most potent supporter. Vitamin A supported the growth but inhibited aflatoxin B, production. Vitamins C and D2 were also repressive particularly for aflatoxin production. The present study included determining the activities of some enzymes in relation to aflatoxin production in A. parasiticus culture during 20 days. Glycolytic enzymes and pyruvate-generating enzymes seems to be linked with aflatoxin B, production. Also, pentose-phosphate pathway enzymes may provide NADPH for aflatoxin B, synthesis. The decreased activities of TCA cycle enzymes particularly from 4th day of growth up to 10th day were correlated with the increase of aflatoxin B, production. All the tested enzymes as well as aflatoxin B, production were inhibited by either catechol or phenol.

No description available.

A numerical model was utilized to assess the effects of elevated temperature on the application of in situ chemical oxidation (ISCO) and enhanced in situ bioremediation (EISB) for the subsurface remediation of trichloroethene (TCE) and tetrachloroethene (PCE). Temperature adjustment of the contaminant physicochemical properties as well as the chemical/biological reactions associated with ISCO and EISB were accounted for in the model domain. ISCO reaction rates were estimated using Arrhenius principles; microbial growth rates for EISB were estimated using non-linear fits to published literature data. The results from this study showed that temperature did provide remedial benefits to ISCO and EISB treatment during the short-term timeframe of oxidant/substrate injection. During these time periods, heated ISCO and EISB treatment exhibited greater DNAPL mass removal and mass flux reduction compared to heated abiotic dissolution. In the long term, after oxidant/substrate injection was terminated, the treatment enhancements achieved by ISCO and EISB were negated. Permeability (k) reduction due to rind formation (ISCO) and bioclogging (EISB) inhibited DNAPL dissolution and contributed to greater dissolution tailing effects. Tailing effects caused by ISCO were more severe compared to EISB since rind formation contributed to permanent k reduction; partial k recovery was observed in the EISB scenarios due to biomass decay. Even though higher temperatures were beneficial to ISCO and EISB during the short-term oxidant/substrate injection period, treatment efficacy was ultimately controlled by the detrimental by-products (rind from ISCO and biomass from EISB) formed as a result of the associative chemical/biological reactions. / Thesis (Master, Civil Engineering) -- Queen's University, 2014-02-10 18:59:23.177