Chemical Survey and Risk Assessment of 56 Pesticides in the Sado River Estuary (Iberian Peninsula, Portugal)

The Sado basin (similar to 8000 km(2)) is an area where intensive agriculture occurs. However, this region still has few data about the water levels of priority pesticides such as fungicides, herbicides, and insecticides. Therefore, water samples were collected every two months at nine sites along the Sado River Estuary and analyzed by GC-MS/MS to determine the influx of pesticides in that ecosystem. More than 87% of the pesticides were quantified, and 42% and 72% were above the maximum totals established by the European Directives 98/83/EC and 2013/39/EU, respectively. Fungicides (91%), herbicides (87%), and insecticides (85%) attained average annual amounts of approximate to 3.2 mu g/L, approximate to 1.0 mu g/L, and approximate to 12.8 mu g/L, respectively. A mathematical approach was used to evaluate the hazard of the pesticide mixture at the maximum concentrations found in this area. The assessment identified invertebrates as the most at-risk trophic level and identified two chemicals (chlorpyriphos and cyfluthrin) as the primary culprits. This assumption was supported by acute in vivo assays using Daphnia magna. These observations, and the high concentrations of phosphates, indicate that the status of the Sado waters poses environmental and potential human health risks.

Automated summary

The Sado basin, an area of intensive agricultural activity, lacks data on water levels of priority pesticides such as fungicides, herbicides, and insecticides. Water samples collected from nine sites along the Sado River Estuary were analyzed, revealing that more than 87% of the pesticides were quantified, with 42% and 72% exceeding the maximum limits established by European Directives 98/83/EC and 2013/39/EU. Fungicides, herbicides, and insecticides had average annual amounts of approximately 3.2 μg/L, 1.0 μg/L, and 12.8 μg/L, respectively. Risk assessment identified invertebrates as the most vulnerable trophic level, implicating chlorpyriphos and cyfluthrin as primary contributors based on acute in vivo assays using Daphnia magna. These findings, coupled with the high phosphate concentrations, indicate environmental and potential human health risks in the Sado waters.