Innovative receiving phase for Chemcatcher® passive sampler for phosphorus in the water environment: Calibration of sampling rate by water temperature and pH.

Passive sampling is a technique for monitoring orthophosphate (PO-P) in the water environment. Compared with traditional grab sampling followed by PO-P quantification, kinetic-type passive samplers such as Chemcatcher® express representative concentrations of PO-P as time-weighted average concentrations (C). They can also potentially evaluate much lower PO-P concentrations, but the available receiving phases of Chemcatcher® used for PO-P were extremely limited. We developed a new receiving phase, the PSfZS sheet, comprising a zirconium sulfate-surfactant micelle mesostructure and polysulfone matrix. We examined its performance in terms of PO-P sorption characteristics, PO-P selectivity, and PO-P sampling rate (R). Its capacity was adequate (12.0 μg-P/cm) and selectivity for PO-P uptake was good. The R for PO-P increased with increasing water temperature (8.1-29.1 °C) and decreasing pH (4.1-9.7) in a laboratory calibration, and ranged from 5.27 × 10 L/d to 1.66 × 10 L/d. We placed the samplers in a municipal wastewater treatment plant, a shallow eutrophic lake, and an oligotrophic caldera lake. The R in the deployment sites was calibrated by monitored water temperature and pH. The estimated C of PO-P in the municipal wastewater treatment plant was similar to the averaged concentration of soluble reactive phosphorus determined by multiple grab samplings. In the lake deployments, we found that the new sampler can quantify C values of PO-P below 10 μg/L, and thus it provides more technical monitoring options and contributes to the conservation and management of the water environment.