Fluazinam in Soil: Analytical Method and Persistence in Boreal Conditions

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http://hdl.handle.net/10138/317729
Title: Fluazinam in Soil: Analytical Method and Persistence in Boreal Conditions
Author: Hakala, Kati P.
Contributor: Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta, Maataloustieteiden laitos
Date: 2020-07
URI: http://hdl.handle.net/10138/317729
Thesis level:
Abstract: Fungal disease late blight (Phytophthora infestans) causes considerable damage to potato crops worldwide. Fluazinam is a widely used pesticide employed against the late blight in potato cultivation. It ends up into soil during spraying and at the end of the growing season when potato foliage is incorporated into the soil. Nevertheless, there is very little literature about behaviour of fluazinam in soil, especially in the conditions that exist in Finland. Therefore, in the preparation of user guidelines, studies made elsewhere are used. From the environmental risks point of view, behaviour of fluazinam in Finnish conditions should be known better. Soils in the boreal zone are characterised by low pH and low temperatures that delay microbiological decomposition and they are typically high in organic matter and saturated by water for long periods in autumn, winter and spring. A prerequisite for assessing the environmental risk of fluazinam is knowledge of its sorption and desorption tendency as well as its degradation rate in boreal conditions. This information is needed, because more aggressive strains of Phytophthora infestans have spread to northern latitudes, increasing the need to use fungicides. In this study, a specific and repeatable high-performance liquid chromatography method utilizing a diode array detector was developed to determine the presence of fluazinam in soil. This method differs from most of the methods found in the literature, which used gas chromatography or gas chromatography-mass spectrometry as an instrument for analysing fluazinam. The method consists of acetonitrile extraction, clean-up with solid-phase extraction and separation using a mobile phase consisting of 70% acetonitrile and 30% water (v v-1), including 0.02% acetic acid. The method was successfully applied to various laboratory experiments and to soil samples collected from potato fields in which fluazinam had been used. In the systematic experiments carried out in controlled conditions, performed with both the fluazinam standard and the commercial product Shirlan®, the effect of soil organic matter on the fluazinam degradation was tested, as well as the persistence of fluazinam in the boreal zone soils for a maximum of one year. The major outcomes of the laboratory experiments were that fluazinam degradation was enhanced by the presence of soil organic matter and even after one year of incubation, more than half of the added fluazinam was recovered. Additionally, soil samples were collected from intensively cultivated potato fields. Over half of these field samples contained varying concentrations of fluazinam, but no substantial accumulation of fluazinam was detected.
Subject: Soil
pesticide
degradation
fluazinam
Shirlan
potato late blight
liquid chromatography
HPLC
boreal
Discipline: Environmental Soil Science


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