Comparison of POCIS passive samplers vs. composite water sampling: A case study

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Water Quality Monitoring

Background:

• Peri-urban rivers receive diverse chemical inputs, necessitating effective monitoring tools.
• Assessing micropollutant levels requires methods that capture both rapid fluctuations and average concentrations.
• Polar Organic Chemical Integrative Samplers (POCIS) are passive devices for long-term water quality assessment.

Purpose of the Study:

• To evaluate the effectiveness of POCIS for measuring 46 pesticides and 19 pharmaceuticals in a peri-urban river.
• To compare POCIS-derived concentrations with daily average water samples, assessing temporal variations.
• To validate POCIS performance against traditional water sampling methods.

Main Methods:

• Deployment of POCIS passive samplers in a peri-urban river.
• Collection of 24-hour average water samples for direct concentration analysis.
• Comparison of micropollutant concentrations obtained from POCIS and water samples.
• Statistical analysis to establish correlations and agreement between methods.

Main Results:

• POCIS provided reliable average concentrations for most studied pesticides and pharmaceuticals.
• A strong correlation (R²=0.89) was found between POCIS and average water sample concentrations for pesticides.
• 75% of all results showed good agreement (ratio 0.33-3) between POCIS and water samples, even with varying sampling rates.
• Identified specific pesticides and pharmaceuticals exhibiting high temporal variations.

Conclusions:

• POCIS is a relevant and effective tool for assessing average concentrations of pesticides and pharmaceuticals in riverine environments.
• The study proposes updated sampling rates for POCIS to improve accuracy in similar river systems.
• POCIS offers a reliable alternative or complement to traditional water sampling for environmental monitoring.