title: Arsenic dynamics in porewater of an intermittently irrigated paddy field in Bangladesh.
abstract: In Bangladesh, irrigation of dry season rice (boro) with arsenic-contaminated groundwater is leading to increased As levels in soils and rice, and to concerns about As-induced yield reduction. Arsenic concentrations and speciation in soil porewater are strongly influenced by redox conditions, and thus by water management during rice growth. We studied the dynamics of As, Fe, P, Si, and other elements in porewater of a paddy field near Sreenagar (Munshiganj), irrigated according to local practice, in which flooding was intermittent. During early rice growth, As porewater concentrations reached up to 500 μg L(-1) and were dominated by As(III), but As release was constrained to the lower portion of the soil above the plow pan. In the later part of the season, soil conditions were oxic throughout the depth range relevant to rice roots and porewater concentrations only intermittently increased to ∼150 μg L(-1) As(V) following irrigation events. Our findings suggest that intermittent irrigation, currently advocated in Bangladesh for water-saving purposes, may be a promising means of reducing As input to paddy soils and rice plant exposure to As.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland. linda.roberts@eawag.ch
authors.forename: Linda C
authors.initials: LC
authors.lastname: Roberts
authors.forename: Stephan J
authors.initials: SJ
authors.lastname: Hug
authors.forename: Andreas
authors.initials: A
authors.lastname: Voegelin
authors.forename: Jessica
authors.initials: J
authors.lastname: Dittmar
authors.forename: Ruben
authors.initials: R
authors.lastname: Kretzschmar
authors.forename: Bernhard
authors.initials: B
authors.lastname: Wehrli
authors.forename: Ganesh C
authors.initials: GC
authors.lastname: Saha
authors.forename: A Borhan M
authors.initials: AB
authors.lastname: Badruzzaman
authors.forename: M Ashraf
authors.initials: MA
authors.lastname: Ali
mesh_terms: D057914:Agricultural Irrigation; D001151:Arsenic / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D001459:Bangladesh; D004784:Environmental Monitoring; D005506:Food Contamination; D005618:Fresh Water / Q000737:chemistry*; D012275:Oryza / Q000254:growth & development / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism
chemical_list: D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D001151:Arsenic