Ecologists investigate the rate of eutrophication in freshwater ecosystems by monitoring the maximum chlorophyll-a concentration (a proxy for algal density) in ponds. Their investigation shows that the eutrophication rate is faster when the Nitrogen to Phosphorus (N:P) ratio of the nutrient runoff is lower, resulting in a higher peak chlorophyll-a level:
The table below shows the mass of nitrogen and phosphorus per litre in runoff samples from three agricultural sources:
| Runoff source | Mass of nitrogen (mg/L) | Mass of phosphorus (mg/L) |
|---|---|---|
| Arable Field | 2.40 | 0.10 |
| Dairy Farm | 1.80 | 0.15 |
| Mixed Orchard | 1.28 | 0.08 |
Determine the Nitrogen to Phosphorus (N:P) ratio for each runoff source, and hence determine which source will cause the fastest rate of eutrophication, explaining your reasoning.