title: Direct and indirect effects of climate change on herbicide leaching--a regional scale assessment in Sweden.
abstract: Climate change is not only likely to improve conditions for crop production in Sweden, but also to increase weed pressure and the need for herbicides. This study aimed at assessing and contrasting the direct and indirect effects of climate change on herbicide leaching to groundwater in a major crop production region in south-west Sweden with the help of the regional pesticide fate and transport model MACRO-SE. We simulated 37 out of the 41 herbicides that are currently approved for use in Sweden on eight major crop types for the 24 most common soil types in the region. The results were aggregated accounting for the fractional coverage of the crop and the area sprayed with a particular herbicide. For simulations of the future, we used projections of five different climate models as model driving data and assessed three different future scenarios: (A) only changes in climate, (B) changes in climate and land-use (altered crop distribution), and (C) changes in climate, land-use, and an increase in herbicide use. The model successfully distinguished between leachable and non-leachable compounds (88% correctly classified) in a qualitative comparison against regional-scale monitoring data. Leaching was dominated by only a few herbicides and crops under current climate and agronomic conditions. The model simulations suggest that the direct effects of an increase in temperature, which enhances degradation, and precipitation which promotes leaching, cancel each other at a regional scale, resulting in a slight decrease in leachate concentrations in a future climate. However, the area at risk of groundwater contamination doubled when indirect effects of changes in land-use and herbicide use, were considered. We therefore concluded that it is important to consider the indirect effects of climate change alongside the direct effects and that effective mitigation strategies and strict regulation are required to secure future (drinking) water resources.
authors: Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 75007 Uppsala, Sweden. Electronic address: Karin.Steffens@slu.se.
authors: Karin
authors: K
authors: Steffens
authors: Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 75007 Uppsala, Sweden.
authors: Nicholas
authors: N
authors: Jarvis
authors: Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 75007 Uppsala, Sweden.
authors: Elisabet
authors: E
authors: Lewan
authors: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
authors: Bodil
authors: B
authors: Lindström
authors: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
authors: Jenny
authors: J
authors: Kreuger
authors: Rossby Centre, Swedish Meteorological and Hydrological Institute, 60176 Norrköping, Sweden.
authors: Erik
authors: E
authors: Kjellström
authors: Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 75007 Uppsala, Sweden.
authors: Julien
authors: J
authors: Moeys
mesh_terms: D000383:Agriculture; D057231:Climate Change; D004784:Environmental Monitoring; D060587:Groundwater / Q000737:chemistry; D006540:Herbicides / Q000032:analysis*; D008956:Models, Chemical; D013548:Sweden; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical
keywords: Climate change; Direct effects; Indirect effects; MACRO; Pesticide modelling; Regional scale