Trends in surface water acidification at ecological monitoring sites in southeastern Canada (1981–1993)

Atmospheric deposition and surface water chemistry have been monitored intensively at 5 geologically “sensitive” sites in southeastern Canada. The sites receive differing acid inputs that span the entire range found in Canada. Surface water data collected at 9 stations from 1981 to 1993 for SO ₄ ^2? , NO ₃ ^? , Alkalinity, DOC, pH, Ca²⁺ and Mg²⁺ have been analyzed to detect monotonic trends. Similarities between the temporal patterns and trends for SO ₄ ^2? in deposition and surface water suggest that they are strongly linked at our sites. Our 13-year datasets showed significant negative SO ₄ ^2? trends at the 3 Ontario sites and a positive trend in Nova Scotia. A climatically-induced SO ₄ ^2? increase in northwestern Ontario has been reversed. Mobilization and export of adsorbed SO ₄ ^2? and/or reoxidized S from the basins of central Ontario sites is delaying their recovery. Two of our 9 stations (in Quebec and central Ontario) are continuing to acidify. The 2 Nova Scotia stations have the highest DOC levels and both exhibit a decreasing trend. Ionic compensation for declining SO ₄ ^2? varies from station to station, sometimes involving an Alk increase, sometimes a base cation decrease, and sometimes more complex combinations. Additional factors (e.g. climatic variation) also influence variable trends, and data records longer than those presently available will be needed to unequivocally verify acidification recovery.     

Development of surface plasmon resonance-based immunoassay for aflatoxin B(1)

Aflatoxins are a group of highly toxic fungal secondary metabolites that occur in Aspergillus species and may contaminate foodstuffs and feeds. Two different anti-aflatoxin B(1) antibodies were examined to develop a surface plasmon resonance (SPR)-based immunoassay to aflatoxin B(1). A conjugate consisting of aflatoxin B(1)-bovine serum albumin (BSA) was immobilized on the dextran gel surface. Competition between immobilized aflatoxin B(1) conjugate and free aflatoxin B(1) in solution for binding to antibody injected over the surface formed the basis for the assay. Regeneration of the antibody from the immobilized conjugate surface is essential for the development of such an inhibitive immunoassay. Problems were encountered with the regeneration of the sensor surface, due to the high-affinity binding of the antibodies. Conventional regeneration solutions consisting of low concentrations of NaOH and HCl worked to a degree, but regeneration was at the expense of the integrity of the immobilized conjugate. A polyclonal anti-aflatoxin B(1) antibody was produced and was found to be regenerable using an organic solution consisting of 1 M ethanolamine with 20% (v/v) acetonitrile, pH 12.0. This combined high ionic strength and extreme pH, as well as chaotrophic properties and allowed the development of an inhibitive immunoassay. The assay had a linear range of 3.0-98.0 ng mL(-1) with good reproducibility.     

Biological pretreatment of sugar cane bagasse for the production of cellulases and xylanases by Penicillium echinulatum

In this study, sugar cane bagasse was pretreated with the white rot fungus Pleurotus sajor-caju PS 2001, and this biomass was subsequently used in the production of cellulases and xylanases by the fungus Penicillium echinulatum. Despite the environmental advantages offered by this type of pretreatment, the enzymatic activity obtained with biologically pretreated sugar cane bagasse (PSCB) was lower than that of the control treatments, which were carried out with untreated sugar cane bagasse (SCB) and cellulose. For medium supplemented with PSCB, the average peak activities obtained were 0.13, 1.0, 0.18, and 0.33 U ml^?1 for FPA, endoglucanase, β-glucosidases, and xylanases, respectively. For the cellulose, control values of 0.52, 1.20, 0.20, and 1.46 U ml^?1, and SCB values of 0.95, 1.60, 0.21, and 1.49 U ml^?1 were obtained, respectively. Although the enzymatic activities of the culture with biologically pretreated sugar cane bagasse were lower than the cultures carried out with untreated sugar cane bagasse, it should be noted that production of enzymes of the cellulase and hemicellulase complex after production of the mushrooms is another way to add value to this agricultural residue.