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The increasing global reliance on pesticides for agricultural pest control has raised significant environmental concerns, particularly due to inadequate monitoring of emerging chemicals in surface waters. This study addresses the potential contamination of aquatic ecosystems by developing and validating a method for detecting trace amounts of four recently registered fungicides: three succinate dehydrogenase inhibitors (fluopyram, penthiopyrad, pydiflumetofen) and fluopicolide, a structurally related fungicide. Employing QuEChERS-based sample extraction combined with ultra-high-performance liquid chromatography (UHPLC-MS-MS), this method achieves detection limits of 0.1 to 0.2 μg/L, with recovery rates between 90% and 110%, and intra-day relative standard deviation values well within the acceptable range of less than 20%. Applied to surface grab water samples from the greater Melbourne area, Australia, the method successfully identified all four fungicides at trace levels, including a notable high concentration of fluopyram (7.3 μg/L) during autumn, with the others intermittently detected at lower concentrations. This study represents the first documented instance of quantifiable detections of these four fungicides in Australian surface water systems. Given their high toxicity to several organisms and the limited global data on these substances, our findings underscore the critical need for continuous monitoring to inform strategies to safeguard aquatic ecosystems from these chemicals.

Pesticide monitoring programs are required to understand pesticide contamination in the environment. They can be used to compare existing water quality guidelines and associated their presence with activities related to catchments. Thus, provide crucial information for management actions. A major challenge with such programs is to determine which pesticides should be screened and this determination is made more difficult as many new pesticides are continuously emerging on markets. We have developed a robust method to identify those pesticides which should be included in screens based on whether they are likely to be used within the region surveyed and if they pose a threat to aquatic ecosystems. This approach is illustrated by comparing the Warrnambool South West (WSW) and Mornington Peninsula (MP) regions within Victoria, Australia that have contrasting land-use practices. Pest control products registered and approved for land-use activities within the two regions during the past decade were identified using a government database. Those pesticides in these products which were not screened by commercial laboratories were then identified. Region-specific identification of prevalent pesticide usage was estimated by matching the highest-grossing agricultural commodities within the two regions with pesticide-specific land-uses. A total of 56 (WSW) and 54 (MP) unique pesticides and another 34 being common in both regions were identified that can be augmented to standard screens of analytical laboratories. Different pesticides of concern are likely to be identified for aquatic ecosystems in other regions of the world; as they will have different regional land-uses, laboratory screens and different pesticide use to those identified in this study. The approach presented here can assist authorities in identifying which pesticides should be incorporated into local pesticide monitoring programs.