Effects of Environmentally Relevant Concentration Exposure Profiles on Polar Organic Chemical Integrative Sampler (POCIS) Sampling Rates

Abstract

Polar organic chemical integrative sampler (POCIS) is a passive sampling device that offers many advantages over traditional discrete sampling methods, but quantitative timeweighted average (TWA) concentrations rely heavily on the robustness of sampling rates. The effects of changing chemical concentration exposures on POCIS sampling rates and its ability to operate in an integrative regime were investigated for 12 pesticides across a range of environmentally relevant concentrations. In five independent 21-day experiments, POCIS devices were exposed to these compounds at constant concentrations ranging from 3 to 60 μg/L and multiple pulsed concentrations with maximum peaks ranging from 5 to 150 μg/L (TWA concentrations = 3 to 92 μg/ L). For the 21-day exposures to constant and pulsed concentrations, there were no significant differences in the POCIS sampling rates between corresponding TWA concentrations. Similarly, there was no significant effect on POCIS ability to operate in an integrative regime. However, loss of linearity was visible for some replicates when exposed to higher pulsed concentrations over an extended period. Modeling and Freundlich isotherms did not predict sorbent saturation, but the extraction and reconstitution protocol likely contributed to atrazine dissolution and subsequent underestimation of sorbed chemical mass when HLB adsorption exceeded 400 μg.

Combining Passive Sampling with Suspect and Nontarget Screening to Characterize Organic Micropollutants in Streams Draining Mixed-Use Watersheds

“…Similarly, the L TWA_stratified / L grab_stratified ratios of OMPs at these two sites were 1.8 ± 1.0 and 1.6 ± 0.8, respectively (Figure S13), suggesting that stratified passive sampling did not introduce statistically significant deviations in load estimation from stratified grab sampling either. Ideally, the rising and falling limbs of a hydrograph should be further stratified for sampling due to fluctuations in POCIS sampling rates and OMP fluxes during different hydrological regimes. , However, optimizing a sampling program is challenging given the dynamic nature of watershed hydrology and stream responses. Moreover, the nonsystematic covariance between concentration (i.e., chemographs) and discharge (i.e., hydrographs) complicated load calculations, so long-term monitoring of OMPs at representative stream sites is required for improved characterization of the covariance to correct for potential bias in load estimation.…”

Characterization of the Permeation Properties of Membrane Filters and Sorption Properties of Sorbents Used for Polar Organic Chemical Integrative Samplers

“…effects of environmental factors on Rs values have been investigated, such as temperature, flow velocity, exposure scenario, and suspended sediment(9,(26)(27)(28). However, the kinetics of the POCIS uptake, which should control Rs values, are not fully understood.…”