Organochlorine pesticides in agricultural soils and associated biota

BEDMAR FRANCISCO; LUPI LEONARDO; KARINA S. B. MIGLIORANZA; WUNDERLIN DANIEL A.

Environmental Earth Sciences

Springer

Año: 2016 vol. 75 p. 1 - 11

1866-6280

The behavior of organochlorine pesticides (OCPs), such as DDTs, endosulfans, HCHs,heptachlors, drins and chlordanes, have been evaluated in the Quequén Grande Riveragricultural watershed including different matrices. Soil profiles from fields dedicated tosoybean cultures and the associated terrestrial biota (earthworms, coleopteran larvae,collembolan and mites), stream water, suspended particle matter and surface sedimentwere sampled during the pre-application pesticide period. Pesticide analyses werecarried out using a gas chromatography with an electron capture detector. Soilssamples showed a differential pesticide pattern throughout the profile. Control soils,settled 200 mts from agricultural plots showed similar pesticide levels but with highervariety of compounds, denoting the historical use of OCPs in the zone. However inagricultural plots DDTs and endosulfans constituted 90% of the pesticides found with afurther enrichment of endosulfan sulfate at depth. The relative high p,p´-DDT levels insurface agricultural soil would be a consequence of pesticide impurities in technicalacaricide Dicofol, which is widely used in the region; and it represents a new threat offresh p,p´-DDT input into environment despite its forbidden use. Terrestrial biota,mainly mesofauna showed high capacity to OCPs accumulation, the aforementionedorganisms being good option in the monitoring of trace pesticides. Furthermore, thehigh OCPs levels found constitute a hazard to food web since these organisms are oneof the first steps in the food chain and the biomagnification is a common process withthese compounds. As a result of runoff and volatilization the occurrence of OCPs in theaquatic environment was observed, draining a load of around 21.5 kg of pesticides intothe river daily.  As a whole, these results suggest the importance of using terrestrialbiota for studying recalcitrant pesticides and a continuous monitoring is stronglyadvised as a first step in minimizing environmental risks.