title: Sprinkler irrigation of rice fields reduces grain arsenic but enhances cadmium.
abstract: Previous studies have demonstrated that rice cultivated under flooded conditions has higher concentrations of arsenic (As) but lower cadmium (Cd) compared to rice grown in unsaturated soils. To validate such effects over long terms under Mediterranean conditions a field experiment, conducted over 7 successive years was established in SW Spain. The impact of water management on rice production and grain arsenic (As) and cadmium (Cd) was measured, and As speciation was determined to inform toxicity evaluation. Sprinkler irrigation was compared to traditional flooding. Both irrigation techniques resulted in similar grain yields (~3000 kg grain ha(-1)). Successive sprinkler irrigation over 7 years decreased grain total As to one-sixth its initial concentration in the flooded system (0.55 to 0.09 mg As kg(-1)), while one cycle of sprinkler irrigation also reduced grain total As by one-third (0.20 mg kg(-1)). Grain inorganic As concentration increased up to 2 folds under flooded conditions compared to sprinkler irrigated fields while organic As was also lower in sprinkler system treatments, but to a lesser extent. This suggests that methylation is favored under water logging. However, sprinkler irrigation increased Cd transfer to grain by a factor of 10, reaching 0.05 mg Cd kg(-1) in 7 years. Sprinkler systems in paddy fields seem particularly suited for Mediterranean climates and are able to mitigate against excessive As accumulation, but our evidence shows that an increased Cd load in rice grain may result.
authors.affiliation: Department of Agricultural Chemistry, Faculty of Sciences, Universidad Autónoma de Madrid, Spain. Electronic address: eduardo.moreno@uam.es.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Moreno-Jiménez
authors.affiliation: Institute for Global Food Security, Queen's University Belfast, Belfast, UK.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Meharg
authors.affiliation: Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, Heverlee, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Smolders
authors.affiliation: Department of Agricultural Chemistry, Faculty of Sciences, Universidad Autónoma de Madrid, Spain.
authors.forename: Rebeca
authors.initials: R
authors.lastname: Manzano
authors.affiliation: Department of Plant Biology, Ecology and Earth Sciences, Universidad de Extremadura, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Becerra
authors.affiliation: Department of Plant Biology, Ecology and Earth Sciences, Universidad de Extremadura, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Sánchez-Llerena
authors.affiliation: Department of Forest and Agricultural Engineering, Universidad de Extremadura, Spain.
authors.forename: Ángel
authors.initials: Á
authors.lastname: Albarrán
authors.affiliation: Department of Plant Biology, Ecology and Earth Sciences, Universidad de Extremadura, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: López-Piñero
mesh_terms: D000383:Agriculture / Q000379:methods*; D001151:Arsenic / Q000032:analysis*; D002104:Cadmium / Q000032:analysis*; D004784:Environmental Monitoring; D005506:Food Contamination / Q000032:analysis; D012275:Oryza / Q000254:growth & development; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D013030:Spain; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D002104:Cadmium; D001151:Arsenic
keywords: Arsenic speciation; Cadmium; Food safety; Rice; Toxicity; Water management