Describe the process of cultural eutrophication, including detailed descriptions about the roles of phosphate/phosphorus, nitrogen (NO_x and NH₃/NH₄⁺), oxygen (O₂), and organic carbon in the cultural eutrophication process. What is the difference between point source and non-point source pollutants? Why are non-point pollutant sources currently more important that point source pollutants in terms of driving continued cultural eutrophication in the United States? (25 points)