Resumen de Metodología para el estudio de la contaminación por pesticidas en la zona no saturada y el acuifero de Gran Canaria y Tenerife (Islas Canarias)
María del Carmen Cabrera Santana, R. Muñoz, Roberto Poncela Poncela, A. R. Socorro, G. González, F. Hernández
Two pesticides and their transformation products were selected far analytical and sampling work at two agricultural areas in the Canary Jslands: glyphosate and AMPA in a banana plantation in Valle Guerra (Tenerife), and metribuzin, MDADK, MOA y MDK in a tomato greenhouse in La Aldea (Gran Canaria). Three methods far sampling the unsaturated zone were compared: soil chemical extraction, the soil solution by means of suction cups and soil solution obtained by centrifugation. The comparison of the three methods shows that soil extracts give a higher pesticide content in the soil, corresponding to the adsorbed and soluble farms of the pesticide. Results far the suction cup samples are difficult to explain due to interactions between adsorption properties of the ceramic cups, amount of pesticide present in the soil solution and "mobile" and "immobile" fractions of- the soil water captured by the devices. Evidence of pesticide pollution in groundwater has been faund at the two studied areas, reaching 13.5 µg.J-1 in groundwater in La Aldea. With the available data, it is not possible to correlate the pesticide applications at the experimental fields with the groundwater concentrations in the two research areas. Hydrogeological studies at these areas show that groundwater represents a mixing between water from the aquifer with irrigation returns, not only from the experimental fields but from all the area.
