Risk for aquatic species associated with the presence of pesticides resulting from horticultural activity: Carnaval creek as a case study

MARINO DAMIÁN; LETICIA PELUSO; MAC LOUGHLIN, TOMÁS M.

Congreso; SETAC Latin America 13th Biennial Meeting; 2019

Pesticides are widely used in the Argentinian agriculturalsystem. Particularly, the intensive horticultural production is highlyreliant on them. Yet, their impact on the surrounding environmentremains unknown. The objective of the current study is to investigate onthe occurrence and concentrations of pesticides in a representative creeksurrounded by horticultural production and if those concentrationspotentially affect the biota. For that purpose, surface water of 5 sitesalong the Carnaval creek (La Plata, Argentina) were studied during 6sampling campaigns encompassing 3 years (n=30). Whole watersamples were extracted with dichloromethane and analyzed by GC-MSfor commonly used insecticides in horticulture. Pesticide concentrationswere compared to the respective quality guidelines for the protection ofaquatic life (PAL), both national and international - when the first wasnot available. Detected occurrences of the insecticides chlorpyrifos(CLP, 14/30; PAL=0.006 ?g/L), cypermethrin (CYP, 5/30, PAL=0.0006?g/L), deltamethrin (DEL, 9/30; PAL=0.0004 ?g/L) and ?-cyhalothrin (?-CYHAL, 4/30; 0.002 ?g/L) were all above guideline. To evaluate ifthese concentrations affect the aquatic biota, the software ETX 2.2(build 201709) was used to obtain a species sensitivity distribution(SSD). LC50 data for aquatic organisms was obtained from USEPA´sECOTOX database. Criteria for the selection were: 96 hours, staticexposure, the earliest life stage (when multiple were available), andmeasured concentrations for bioassays. Input LC50 data followed anormal distribution (Anderson-Darling test, ?=0.01). Of each SSD fitted,a HC5 (hazardous concentration at the 5th percentile) was calculated:CLP=0.03 ?g/L; CYP=0.1 ?g/L; DEL=0.02 ?g/L; ?-CYHAL=0.003?g/L. HC5 were all above the respective guideline. The species fractionaffected for the maximum concentration of each pesticide were alsocalculated: CLP 37%; CYP 84%; ?-CYHAL 11%, DEL 97%. Maximumfor the first three pesticides were all from the same campaign. Fractionaffected for the median concentrations were all above 5%, that is,median concentrations were above HC5. These results, both HC5 andFA for median and maximum concentrations, show that pesticides,specifically insecticides, found in a horticulture-impacted creek have thepotential to affect negatively the aquatic biota.