Need help with some bio questions. cant seem to find answers

[Niko]

my bio teacher wants me to research these questions on the internet and i cant find answers:

what are normal values of ph in a freshwater community?

what are normal values of dissolved oxygen in a fresh water community?

where do nitrates come from, and can they be harmful or helpful in a freshwater community? why?

[Niko]

my bio teacher wants me to research these questions on the internet and i cant find answers:

what are normal values of ph in a freshwater community?

what are normal values of dissolved oxygen in a fresh water community?

where do nitrates come from, and can they be harmful or helpful in a freshwater community? why?

Got the last one... now just the first two...

[NiamhC]

Most sources i can find seem to have the acceptable levels of pH in freshwater as between 6.5 and 8.5, with 7.0 being neutral.

Also, from what i can see the oxegen levels are about 8ppm.

Just google: pH levels, freshwater
and Dissolves Oxegen, freshwater

and you should find some pages that'll help you out.

[Niko]

Most sources i can find seem to have the acceptable levels of pH in freshwater as between 6.5 and 8.5, with 7.0 being neutral.

Also, from what i can see the oxegen levels are about 8ppm.

Just google: pH levels, freshwater
and Dissolves Oxegen, freshwater

and you should find some pages that'll help you out.

Thanks so much!!! right on time, too. thoses were the only ones i hasd left and the assignment was rue tommorrow!!

[paperclip]

How about the buffering capacity of hydrocarbonates in fresh water samples, not to mention the effects of metallic cations and metallic anions? like how about sulphates too?

[Jokkon]

do nitrates come from algae? i think i learned aobut that a few years back

[mith]

No, algae uses nitrates and profilerates where nitrates exist. You're confusing cause and effect.