The factors that change the pH of water, runoff of nitrogen and phosphorus

The factors that change the pH of water, runoff of nitrogen and phosphorus Paper details basically what I’m doing is collecting water samples, each area I’m collecting 2 water samples and one of the samples I’m letting the water sit there for a week and let it dioxide and measuring the nitrate since i don’t have the tools to measure the phosphorus. and the second bottle of water that i collected from the same area I’m adding fertilizer since it has phosphorus and nitrate in it already, and seeing how much fertilizer can make the water to bad for the aquatic environment.