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dc.contributor.authorBeauchamp, Stephen.en_US
dc.date.accessioned2014-10-21T12:34:36Z
dc.date.available2014-10-21T12:34:36Z
dc.date.issued1990en_US
dc.identifier.otherAAINN64380en_US
dc.identifier.urihttp://hdl.handle.net/10222/55169
dc.descriptionWater chemistry, sediment geochemistry, and acid phosphatase activity were examined in selected lakes in Atlantic Canada to asses the impact of lake water acidification on phosphorus availability. Sediment phosphorus flux rates in 25 lakes ranged from $-$0.007 to 0.361 mgP$\cdot$m$\sp{-2}\cdot$d$\sp{-1}$. Sediment phosphorus flux was not significantly correlated with lake water acidity, but was correlated (p $<$ 0.01) to lake trophic status and dissolved organic carbon (DOC) concentration. Comparisons with lake phosphorus budgets, suggest that sediment phosphorus loading was negligible.en_US
dc.descriptionLower Ca concentrations in surface sediments was evident in some lakes. Greater Al flux from sediments was measured with increasing lake acidity. Lower pH in experimentally acidified cores indicated that aluminum, iron, manganese and calcium were mobilized from sediments, while soluble reactive phosphorus (SRP) was removed from the water column.en_US
dc.descriptionGreater phosphatase activity in lake water was generally associated with low pH and high DOC, aluminum and iron concentrations. Phosphatase activity was found to be highly pH dependent. Enzyme pH optima closely approximated that of ambient lake water in 4 lakes ranging in pH from 4.5-6.3. Little Springfield Lake (pH 3.8) showed a pH optima closer to its preacidification pH suggesting that enzyme modification to acidification may be slow. Inorganic Al added to water samples was found to inhibit enzymatic hydrolysis of organic phosphorus substrates to varying degrees depending on DOC content. The lack of substantial interference in the presence of large Al concentrations mobilized from sediments in acidified cores suggested that the Al mobilized from sediments was unreactive. Phosphatase activity in core water and surface sediments decreased with increased acidity down to pH 4.0, largely due to reductions in enzyme efficiency due to pH. Enzyme activity normalized for changes in efficiency due to pH, indicated greatest increases enzyme production at pH $<$ 4.0. Increased acid phosphatase activity under increasingly acidic conditions may be related to removal of soluble reactive phosphorus (SRP) by direct phosphorus-metal interactions or enzyme inhibition but may also be a response reduced enzyme activity at lower pH.en_US
dc.descriptionGreater acidity was found to reduce DOC concentrations which may reduce enzyme substrate availability and reduce metal-organic complexation which could increase metal toxicity or reduce phosphorus availability through direct phosphorus-metal interactions.en_US
dc.descriptionThesis (Ph.D.)--Dalhousie University (Canada), 1990.en_US
dc.languageengen_US
dc.publisherDalhousie Universityen_US
dc.publisheren_US
dc.subjectEnvironmental Sciences.en_US
dc.subjectGeochemistry.en_US
dc.titleFactors influencing flux, mineralization and availability of phosphorus in clear and organic lakes in the Atlantic Region.en_US
dc.typetexten_US
dc.contributor.degreePh.D.en_US
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