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r. <br /> Table 1. Design Factors for ProMec Controlled Release Bactericides <br /> -Chemical Environment- <br /> moisture content, acidity, pyrite content+ <br /> Physical, Environment <br /> particle size distribution, soil cover, slope; accessibility, <br /> degree of vegetation, type of overburden material, age of <br /> material (state of acid production) <br /> Hydrology <br /> percolation rates, runoff rates <br /> Climate <br /> ' precipitation (average and events-form) ," temperature (average <br /> and extremes) <br /> little rainfall require quick releasing pellets while regions that <br /> receive an abundance of snow or rain require slow releasing pellets. <br /> High altitude=regions are often-characterized 1;y low temperatures, <br /> heavy snowfall,, short•, growing seasons,,and shallow soils. _ Regardless <br /> of - temperature,•_,-bacteria -are present'.- in' high altitude.environments, <br /> although 'they may not be metabolically aative.� Wtien'temperatures fall <br /> -below 0°C,'water is no longer mobiie'and.the' controlled release pellets <br /> •do-= not- release bactericides.' " During -periods `of r-freeze, `'biotic <br /> oxidation does not occur and there is no need for bactericidal release <br /> since bacteria are not very active below 20C (Ferroni, et al, 1986) . <br /> A study_ of T.- ferrooxidans -in subarctic. British Columbia found <br /> that' surface: temperatures in the brief• summer reached •150G. _In;the low <br /> pH`--'environment;= ' T. ferrooxidans was ° quite''"capable"'of establishing <br /> populations ' sufficient to catal$ze acid generation.-' Sulfate generation <br /> `increased ` fivefold for every 10 C increase in temperature when bacteria <br /> were present, while sulfate generation only increased twofold -in an <br /> abiotic environment with each temperature increase of, 10°C (Halbert, et <br /> al,''1983) < _,'„_ ;- r <br /> THE NATURAL DYNAMIC CYCIEL <br /> -- <br /> Prior to mining, the soil envirQnment-`and its biota have- <br /> defenses <br /> against acid-generating bacteria -and the acidic•_byproducts. Once the <br /> land ii'-drastically disturbed and,: sulfides' are'exposed_to•water and <br /> - oxygen, an ' acidic environment " .becomesl""''established: ` Then,-:'*T. <br /> ferrooxidaris.- -populaiions will increase dramaticalip and-acid production <br /> will, be accelerated.'. ' The 'calcareous content_ bf.�the^ -soil will be <br /> overwhelmed and'unable`to-'neutralize'all the acid formed:` "' <br />