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AMQAW Meeting. Comments on Mainstem Replicate Sampling Procedure June 2006. NUTRIENT CONCENTRATIONS Comparisons Among Estuaries Data assembled by NASL staff Summary developed by Jerry Frank Very large range in concentrations in USA estuaries
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AMQAW Meeting Comments on Mainstem Replicate Sampling Procedure June 2006
NUTRIENT CONCENTRATIONS • Comparisons Among Estuaries • Data assembled by NASL staff • Summary developed by Jerry Frank • Very large range in concentrations in USA estuaries • Generally highest in winter and lowest in fall • Generally highest in oligohaline areas and lowest in lagoons
NH4 before Field Technique Changes 20% error 7uM
NH4 after Field Technique Changes • Wear gloves • cup rims not touched • rinsing of cups and caps • cup arrangement in rack 20% line 7 uM
SAV Criteria Way out there 0.014 mg/l 0.14 mg/l
DIN Criteria • SAV DIN Criteria = 11 uM (0.15 mg/l) • MDLs for NH4 range from 0.6 to 0.9uM • Detection is great relative to criteria • Main interest is with higher values (bad WQ for SAV) where replicate variability is low (<5%)
Summary • Changes in field procedures have helped • Basic advantage of in-field stabilization, esp for NH4 which is very reactive • Most replicate variability at very low concentrations (occasionally a lot of very little) • Replicate variability does not seem to influence several uses of monitoring data • Continue emphasis in careful field and lab procedures
