Environmental Risk Assessment in a Peri-Urban Stream Surrounded by Horticultural Production

MAC LOUGHLIN, TOMÁS M.; PELUSO, MARÍA LETICIA; MARINO, DAMIÁN J. G.

Congreso; SETAC Latin America 14th Biennial Meeting; 2021

A wide variety and load of pesticides are applied in horticulture due to each production unit having multiple crops simultaneously. The horticultural greenbelt of La Plata (Argentina) is one of the most important in the country with more than 6,000 ha. Despite the relevance of this activity, there is a paucity of information on the impact of horticulture to aquatic environments. The occurrence of mixtures is a big concern due to their potential additive or synergistic effects. Environmental Risk Assessments (ERA) facilitate the modeling of theexpected toxicity of pesticide mixtures. The objective of this work is to analyze the concentration of pesticides in surface water and estimate the risk they represent for aquatic biota. Surface water of 5 sites along the Carnaval creek were studied during 6 sampling campaigns for 3 years (n=30). Samples were extracted with dichloromethane and analyzed byGC-MS for current and legacy pesticides. Precolumn derivatization with FMOC-Cl was performed for glyphosate AMPA analysis by UPLC-MS/MS. Acute and chronic (no observed effect concentration [NOEC]) toxicity endpoints for fish, aquatic invertebrates, and algae were obtained from the Pesticide Properties Database. Risk quotients (RQ) were calculated as the ratio between measured environmental concentration and the predicted no effect concentration (lowest NOEC divided by an assessment factor dependent on data availability). Concentration addition effect was assumed. RQ≥1 indicates high environmental risk. In 5 out of 6 sampling campaigns, at least one pesticide was detected every sample. Glyphosate (67%) and AMPA(83%) were the most detected, followed by the insecticides chlorpyrifos (47%), deltamethrin (30%) and the fungicide azoxystrobin (30%). Maximum detected concentrations were glyphosate 20.04 μg/L, AMPA 4.86 μg/L, deltamethrin 3.944 μg/L, cypermethrin 3.888 μg/L, and chlorpyrifos 2.645 μg/L, exceeding previously reported values. The ERA showed more than half of the sites presented RQ≥1. Furthermore, 30% of the samples presented a RQ greater than 1,000, and three values exceeding 10,000. Glyphosate and AMPA, despite being the most detected, contributed a maximum RQ of 0.24. Pyrethroids considerably contributed to the greater values RQ, with the lowest concentration representing RQ=20 (λ-cyhalothrin 0.004 μg/L) and the highest RQ=48094 (deltamethrin 3.944 μg/L). Horticulture, because of currently used insecticides, poses a great risk on aquatic biota.