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<p>This study examines whether distinct monitoring strategies result in notable differences when estimating annual average and peak concentrations of micropollutants in rivers (adherence to environmental standards) and annual riverine loads. Three different sampling techniques were employed over the course of a&#xa0;year at two locations within the Wulka River basin. The primary monitoring site on the Wulka River is characterized by a&#xa0;catchment heavily affected by farming activities and significant discharges from municipal wastewater treatment plants. The catchment of the second sampling location on the tributary Nodbach is also dominated by agricultural land use but it does not receive discharges from wastewater treatment plants. Grab samples were collected manually every two weeks, while continuous sampling was performed using two automated, refrigerated samplers operated simultaneously to gather time- and volume-proportional composite samples over 14-day periods. Four categories of micropollutants were selected to reflect different emission and transport patterns in river catchments: trace metals (total and dissolved), pharmaceuticals, per- and polyfluoroalkyl substances (PFAS), and pesticides.</p><p>For substances that are introduced continuously, such as commonly used pharmaceuticals or dissolved metals, preliminary evaluations of annual average concentrations can be carried out using 12 grab samples without significant systematic deviations. Composite samples offer advantages when emissions and river concentrations fluctuate over time. Substances with seasonal application, such as most pesticides, require special consideration through composite sampling over extended periods. Measuring the concentrations, and especially the loads, of contaminants released during specific events (e.g., certain pesticides, certain PFAS, total metals) poses challenges when using grab samples. In the context of discharge-driven pollution events, composite samples, particularly volume-proportional composites, have shown to be highly beneficial. Another approach is to collect grab samples specifically during such events using targeted sampling. If substances are emitted in brief pulses (in the study’s catchment, this likely applies to the insecticide lindane), they may be undetected by grab sampling. In such cases, composite samples are essential to ensure detection.</p>

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Der Einfluss der Probennahme auf die Erfassung von Spurenstoffkonzentrationen und -frachten in Fließgewässern

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2025年9月26日

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  • Nikolaus Weber,
  • Steffen Kittlaus,
  • Christine Hufnagl,
  • Jounes Lutterbach,
  • Matthias Zessner,
  • Ottavia Zoboli

摘要

This study examines whether distinct monitoring strategies result in notable differences when estimating annual average and peak concentrations of micropollutants in rivers (adherence to environmental standards) and annual riverine loads. Three different sampling techniques were employed over the course of a year at two locations within the Wulka River basin. The primary monitoring site on the Wulka River is characterized by a catchment heavily affected by farming activities and significant discharges from municipal wastewater treatment plants. The catchment of the second sampling location on the tributary Nodbach is also dominated by agricultural land use but it does not receive discharges from wastewater treatment plants. Grab samples were collected manually every two weeks, while continuous sampling was performed using two automated, refrigerated samplers operated simultaneously to gather time- and volume-proportional composite samples over 14-day periods. Four categories of micropollutants were selected to reflect different emission and transport patterns in river catchments: trace metals (total and dissolved), pharmaceuticals, per- and polyfluoroalkyl substances (PFAS), and pesticides.

For substances that are introduced continuously, such as commonly used pharmaceuticals or dissolved metals, preliminary evaluations of annual average concentrations can be carried out using 12 grab samples without significant systematic deviations. Composite samples offer advantages when emissions and river concentrations fluctuate over time. Substances with seasonal application, such as most pesticides, require special consideration through composite sampling over extended periods. Measuring the concentrations, and especially the loads, of contaminants released during specific events (e.g., certain pesticides, certain PFAS, total metals) poses challenges when using grab samples. In the context of discharge-driven pollution events, composite samples, particularly volume-proportional composites, have shown to be highly beneficial. Another approach is to collect grab samples specifically during such events using targeted sampling. If substances are emitted in brief pulses (in the study’s catchment, this likely applies to the insecticide lindane), they may be undetected by grab sampling. In such cases, composite samples are essential to ensure detection.