chemical parameters：化学参数

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1、ChemicalParametersforWaterStudypHpH=potentialofHydrogenpHisameasureofthedissolvedhydrogenionconcentration[H+]inwater.Itisfoundbydeterminingthenegativelogofthehydrogenionconcentration.pH=-log[H+]ItscounterpartispOHwhichisameasureofthedissolvedhydroxideionconcen

2、tration[OH-]inwater.Itisfoundbydeterminingthenegativelogofthehydrogenionconcentration.pOH=-log[OH-]Purewaterionizestoformequalamountsofhydrogenandhydroxideions:HOHH++OH–Theconcentrationofeachioninasolutionofpurewateris1X10-7M(molesperliter).Sincethelogofthisnu

3、mberis-7,thepHis7andthepOHisalso7.PurewaterhasaneutralpHbecausetheconcentrationofhydrogenandhydroxideionsareequal.ThisleadstothepHscale(anditscounterpartpOHscale)with7inthemiddle.Aconcentrationof10-6ismoreconcentratedthan10-7.10-5ismoreconcentratedthan10-6ands

4、oon.ConcentrationpHpOHConcentration0012345677654321891011121314891011121314HighConcentrationHighConcentrationLowConcentrationLowConcentration100M10-1M10-2M10-3M10-4M10-5M10-6M10-7M10-8M10-9M10-10M10-11M10-12M10-13M10-14M10-14M10-13M10-12M10-11M10-10M10-9M10-8M

5、10-7M10-6M10-5M10-4M10-3M10-2M10-1M100MpHRangesandAquaticLifepHAcidic0_________________________7________________________________14BasicBacteria1_________________________________________________13AquaticPlants6.5______________________________13Carp,Suckers,Catf

6、ish,6_________________________________13someinvertebratesBass,Crappie6.5_____________9Snails,Mussels7__________9Amphibians5___________________9Mostothers6.5____7.5http://www.adopt-a-stream.org/parameters.phpRainisnaturallyacidic(pH5.0–6.0)duetotheabsorptionofc

7、arbondioxideintheatmosphere.UsuallyaloweredpH(moreacidic)hasgreateraffectonaquaticorganisms.ToxicityofmanycompoundsincreasesatlowerpHandthesolubilityofmetals(aluminum,copper)alsoincreasesatlowerpH.Bothhaveadirecteffectontheviabilityofaquaticorganisms.SourcesEa

8、rthForceWaterQualityStandardshttp://www.eeweek.org/assets/files/Water%20Quality%20Testing/Water%20Quality%20Parameters.pdfUSEPA–AcidRainhttp://www.epa.gov/acidrain/effects/surface_