Sources and Losses of Arsenic to Paddy Fields

Abstract

Arsenic in rice is derived from the soil matrix that sustains it. Paddy field biogeochemistry leads to excessive arsenic mobilization and subsequent assimilation by rice (see Chap. 5), though arsenic has to be present in the first place to be mobilized, which will be the subject of the present chapter. While a consideration of the inputs and sources of arsenic into paddies is important, so are potential losses from the soils, and it is becoming apparent that a mass balance approach is required (Dittmar et al. 2010; Neumann et al. 2011; Roberts et al. 2010). Furthermore, it is starting to be realised that in some agro-ecosystems, particularly the groundwater irrigated paddies of SE Asia, that rice cultivation may greatly alter wider arsenic biogeochemical cycles through the surface to groundwater continuum, potentially affecting groundwater arsenic (Burgess et al. 2010; Neumann et al. 2010). This topic will also be considered here.