Effect of varying post field collection filtration times on lake water nutrient analysis for Green Lake 3 and Green Lake 4, 2025.

After field collection, filtration time on lake and stream samples can vary. To test how this affects nutrient measurements we filtered samples from Green Lakes 3 and 4 at the time of collection in the field, immediately upon returning to the lab, 24 hours, and 48 hours after collection. Samples were then frozen and analyzed for chloride, nitrate and sulfate. Chloride and nitrate were below detection limits so only sulfate is reported. There was no statistically significant loss of sulfate as time progressed, indicating current filtration methods (<48 hours after collection) are acceptable for samples being analyzed via ion chromatography.