Performance of a passive sampler for the determination of time averaged concentrations of nitrate and phosphate in water
Environmental Science: Processes & Impacts
A passive sampler device for the kinetic accumulation of nitrate (NO 3 -) and phosphate (HPO 4 2-) in water was developed and 15 calibrated. The sampler incorporates an ion exchange disk as receiving phase and selectively collects nitrate and phosphate at sampling rates of 197 ± 43 and 75 ± 12 mL day -1 , respectively. Minimum exposure times under nutrient rich and nutrient poor conditions were estimated to be 3 and 27 days respectively for 20 phosphate and 1 and 7 days respectively for
... ctively for nitrate. The influence of the environmental variables pH (5-9), temperature (7-21 º C) and turbulence (50-400 rpm) on sampling rates investigated. Temperature was found to have a significant influence on uptake rates for both anions, while pH influenced phosphate only. Water 25 turbulence did not influence the uptake rates under the studied conditions. A series of field studies was conducted at a municipal wastewater treatment plant. Results for the passive sampler were lower than concentrations obtained using conventional measurement methods, due to methodological differences, and 30 biofouling was found to affect the results for sampling periods over 3 days. This study shows that passive sampling can be used to monitor nitrate and phosphate concentrations in aqueous media. The approach provides an interesting alternative to grab sampling as it yields time-averaged concentrations of the 35 analytes.