Rainfall-induced removal of copper-based spray residues from vines P. Pérez-Rodríguez a,n , D. Soto-Gómez a , I. De La Calle b,c , J.E. López-Periago a , M. Paradelo a,d a Área de Edafoloxía e Química Agrícola, Dpto. Bioloxía Vexetal e Ciencia do Solo, Facultade de Ciencias, Universidade de Vigo, Ourense 32004, Spain b Departamento de Química Analítica y Alimentaria, Área de Química Analítica, Facultad de Química, Universidad de Vigo, Campus As Lagoas-Marcosende s/n, 36310 Vigo, Spain c Ultra Trace Analyses Aquitaine UT2A/ADERA, Hélioparc Pau-Pyrénées, 2 avenue du Président Angot, 64053 PAU cedex 9, Pau, France d Department of Agroecology, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, P.O. Box 50, 8830 Tjele, Denmark article info Article history: Received 1 December 2015 Received in revised form 18 April 2016 Accepted 15 June 2016 Available online 23 June 2016 Keywords: Copper Fungicide Rainfastness Tenacity Throughfall Wash-off abstract The continuous use of copper against fungal diseases and off-target effects causes major environmental and agronomic problems. However, the rain-induced removal of Cu-based residues is known only for a limited number of crops. We present the results of rain-induced removal of fungicides from two mon- itored vineyard plots which were sprayed with two widely used Cu-based formulations: copper-oxy- chloride (CO) and Bordeaux mixture (BM), respectively. Cu removal per growing season was 0.60 70.12 kg ha 1 (30% of the applied fungicide) for CO and 0.80 70.10 kg ha 1 for BM (70% of the applied fungicide). Fractioning the Cu in soluble (Cu S ) and particulate fractions (Cu P ) showed that most of the Cu was removed as Cu P , but Cu S concentrations found in throughfall collectors exceeded the reg- ulatory threshold for toxicity in surface waters. The first few millimeters of rain caused most of the Cu removal. Our findings agreed with the data reported in the scientific literature, in which a significant fraction of the Cu-based formulation is loosely attached to the plant surfaces. In addition, we found that rainfall energy had a minor influence on the removal. & 2016 Elsevier Inc. All rights reserved. 1. Introduction The excessive use of copper, and its release to the environment, is a serious issue in many different crops (e.g., vines, apple, pear, tomato, potato, olive and kiwifruit). In practical terms, almost all the Cu that is sprayed reaches the soil in a direct way (e.g., spray droplets fall directly to the soil or non-target organisms) or in an indirect way (rain-removal, leaf drop and decomposition). There- fore, the total input into soil can be easily derived from the applied amount. In the case of vineyards, Cu concentration in soils can reach phytotoxic levels ( 4100 mg kg 1 )(Chaignon et al., 2003; Fernández-Calviño et al., 2008b; Pietrzak and McPhail, 2004). This topic has led to several studies on Cu behavior in soils (Fernández- Calviño et al., 2008b, 2010; Komárek et al., 2009; López-Periago et al., 2008), whose mobility and bioavailability depend on factors such as the pH conditions and the organic matter content of the soil. The use of copper is allowed in organic farming (Official Journal of European Community, 2008); therefore, a decrease in its use as a fungicide is not expected. Thus, studies dealing with the removal of Cu by rain are important from the agricultural point of view. If Cu is removed, new treatments have to be applied to keep the plants protected against fungal pathogens. This practice also implies environmental consequences: first, one issue is the in- crease of the amount applied, but, in addition, the Cu from treat- ments produces mobile substances containing Cu, as demon- strated by its presence in surface waters and its accumulation in river bed sediments away from the vineyards (El Azzi et al., 2013; Fernández-Calviño et al., 2008c). The removal of agrochemicals from leaves by the impact of rain droplets, and the carry-out of active ingredients by a water-film, has been well described for several crops such as cocoa, coffee, peanut plants and kiwifruit (Lima, 1994; Loland and Singh, 2004; Wauchope et al., 2004b; Rudgard et al., 1990; Hunsche et al., 2006, 2011; Gaskin et al., 2013 and cites therein). Moreover, rain wash-off from leaves has been characterized by simulated rain and field experiments (Mohr et al., 2007, 2008a, 2008b) in the strategy program to reduce Cu-use in vineyards. However, the influence of the rainfall characteristics on the wash-off is still under discussion because of the diversity of re- sults. For instance, Provenzano et al. (2010) provided evidence that in the natural conditions typical of a Mediterranean en- vironment, characterised by calcareous soils and a dry climate, residues of Cu on berries and leaves were not affected by rain. In addition, Xu et al. (2008) concluded that the loss of fungicides such as Captan is mainly due to rain, and the loss is negligible under dry conditions. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ecoenv Ecotoxicology and Environmental Safety http://dx.doi.org/10.1016/j.ecoenv.2016.06.020 0147-6513/& 2016 Elsevier Inc. All rights reserved. n Corresponding author. E-mail address: paulaperezr@uvigo.es (P. Pérez-Rodríguez). Ecotoxicology and Environmental Safety 132 (2016) 304–310