Download Pesticide mobility in soils with different uses

Thiacloprid and fenarimol mobility in two contrasting mine
soils
J.A. Rodríguez-Liébana*, M.D. Mingorance, A. Peña
Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Avda. de las Palmeras, 4.
18100-Armilla, Granada (Spain)
* Presenting author contact: [email protected]
In Andalusia (south of Spain) mining activities, which contribute more than 50% to the
national metallic mineral production, have generated during centuries large degraded
zones which could be exploited for agricultural purposes, once remediated. In these
cases pesticide application is needed. However, the use of pesticides for the control of
pests, a widely adopted agricultural practice, may impair environmental safety because
of pesticide leaching to deeper soil layers and groundwater. In general, pesticide
mobility through the soil profile will depend on pesticide physicochemical properties,
on soil properties and on the properties of the flowing influent. Therefore the behaviour
of two pesticides, thiacloprid (THC) and fenarimol (FEN), chemically very different, in
two mining soils with contrasting properties has been assessed.
A basic mine soil from Alquife (province of Granada, eastern Andalusia) and an acid
mine soil form Nerva (province of Huelva, western Andalusia) have been evaluated.
The experiments were carried out using small polypropylene columns (2.6 cm i.d., 5 cm
long) with packed soil. Steady state flow conditions were established to allow the
influent solution to flow through the soil under positive pressure head. Triplicate test
columns at room temperature (20 ºC) were performed and leachates were characterised
at regular intervals. To identify relevant parameters related to pesticide mobility,
breakthrough curves were fitted with the convection dispersion transport model and
retardation factors and partitioning coefficients were calculated.
The peak maxima in both soils for THC were less delayed relative to bromide than
those of FEN, more retained, in agreement with previous pesticide sorption assays in the
soils. Both pesticides were more retained in Nerva than in Alquife soil, likely due to
their different organic carbon content (14 and 9.4 g kg-1, respectively). Irrigating
Alquife soil after application of THC and FEN could result in higher groundwater
contamination potential because of an increased infiltration rate.
J.A. Rodríguez-Liébana thanks CSIC for a predoctoral fellowship, co-financed by ESF. The Junta de
Andalucía through Proyecto de Excelencia (P10-RNM5814), cofinanced by FEDER funds, has supported
this research.