Time integrative passive sampling: how well do chemcatchers integrate fluctuating pollutant concentrations?

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Environmental Monitoring

Background:

• Periodic fluctuations in pollutant concentrations are common in many environments.
• Passive samplers offer time-weighted average concentration data, ideal for such conditions.
• Investigating sampler performance under fluctuating concentrations is crucial for data reliability.

Purpose of the Study:

• To evaluate the performance of passive samplers under fluctuating herbicide concentrations.
• To compare observed uptake with model predictions for different sampler configurations.
• To assess the suitability of passive samplers for environments with dynamic pollutant levels.

Main Methods:

• Chemcatchers with SDB-RPS Empore disks were deployed for 28 days in a calibration chamber.
• A 10-fold concentration pulse event was introduced, followed by a return to background levels.
• Observed uptake was compared to predictions from first-order and reduced-form uptake models for various sampler designs (membrane-covered, one-sided naked, two-sided naked).

Main Results:

• Membrane-covered samplers predicted time-weighted average concentrations within a factor of 0.7-1.2.
• One-sided naked samplers underpredicted by a factor of 1.9-2.2.
• Two-sided naked samplers underpredicted by a factor of 2.4-3.2.
• First-order modeling accurately predicted uptake for membrane-covered and one-sided naked samplers.

Conclusions:

• Membrane-covered passive samplers are reliable for monitoring environments with fluctuating herbicide concentrations.
• Naked passive samplers significantly underpredict average concentrations during pulsed events.
• First-order uptake models can accurately predict passive sampler performance under dynamic conditions.