Ocurrence and spatial-temporal trends of monensin in a mixed-uses watershed in Argentina.

PÉREZ DJ.,; MENONE, M.L.; CANTÓN, G; DE GERÓNIMO, E

Sacramento

Congreso; SETAC NorthAmerica 39th Annual Meeting.; 2018

Society of Environmental Toxicology and Chemistry

Occurrence and potential ecological risk of veterinary medicines inaquatic ecosystems of South America, is not well reported. This workattempts to generate relevant data about the occurrence, levels andspatial-temporal trends of monensin (MON) in a mixed-uses watershedof Argentina. El Pantanoso is a first-order stream located in the southeastof the Buenos Aires Province, with a catchment area of 476 km2.This watershed is influenced by urban and farming activities. There is aConstructed Channel (CC) that receives the wastewater plant treatment(WWPT) discharge of Balcarce City and effluents of a feedlot production;and it is coupled to the stream in the main channel. Water samples werecollected from 11 sampling sites in August and November 2017 coveringthe high flow and low flow periods, respectively. Sampling sites werechosen to cover from the headwaters to the end of stream in the floodplaincontemplating different possible points of pollution by veterinarymedicines. Samples was collected by triplicate using 1 L polypropylenebottles and stored at -20°C until analysis. Samples were analyzed usingliquid chromatography coupled to a tandem mass spectrometer. Thelimit of detection (LOD) was set in 0.01 μg/L and the limit of quantificationwas estimated similarly to the LOD. MON was detected in 90% and100% of the samples in August and November, respectively. In August,at headwaters and floodplain MON was detected at minimum levels(0.2 ± 0.03 μg/L) associated with the extensively livestock production.Highest MON levels were detected associated with cattle slaughter wastewater effluent (2.6 ± 0.74 μg/L). In the CC, the levels varied from nondetected at the beginning with urban and periurban influence, to 1.0 ±0.1 μg/L downstream to the WWPT, and 0.6 ± 0.03 μg/L downstreamto the feedlot production. In November, the levels no surpass 0.02 μg/Lat different sites. MON occurrence become an ubiquitous emergentcontaminant in this watershed. Cattle slaughter was the main point sourcepollution of MON and the WWPT result the secondary source of impact.The highest concentrations found close to the cattle slaughter in Augustcould be explained for the intense rains during this period that induceda strong drainage from the treatment lagoon to the stream, because thedistance between both sites is less than 0.5 km. This is the first report thatdescribes the presence of monensin in surface waters of Argentina.