Heavy metal availability assessment using portable X-ray fluorescence and single extraction procedures on former vineyard polluted soils

Abstract

The periodic application of copper-based fungicides (Bourdeaux mixture) to vineyards of the Mediterranean region has generated an important pollution source that in some cases requires a quick intervention due to the high bioavailable copper content measured. Despite some vineyards were abandoned 40 years ago, noticeable amounts of Cu and other man-related metals are still nowadays detected in soils. In the present work, the development of a mobility test for the available heavy metal (Cu, Pb, Zn and As) content in soil has been performed using portable X-ray fluorescence (FP-XRF) combined with single leaching test, and was applied to a calcareous soil of a former vineyard area in Catalonia (NE Spain). The combined methodology has provided useful information for fast and detailed risk assessment, in terms of mobility and bioavailability of metals. The anthropogenic contribution was evaluated by means of the Concentration Enrichment Ratios (CER) in soil. The results reflect a clear anthropogenic contribution for Cu, a partial anthropogenic contribution for Pb proceeding from an external pollution source, and a non-significant external contribution for As and Zn. The topsoil concentration ranges for Cu (70–128 mg kg−1) were found to be above the background level and several samples above the regional governmental limits (Generic Reference Levels or GRL values) for soil ecosystem protection and for human health (90 mg kg−1). The present study reveals that the use of FP-XRF equipment constitute a highly valid option for quick decision making during the field location, characterization and quantitative elemental analysis of soil samples for screening of potential pollutants such as heavy metals.