Cadmium distribution and cycling in forest-rice agroforestry systems in Northern Hunan

Abstract

Cadmium (Cd) and its compounds are highly toxic to living organisms and are an environmental health hazard. Rice plants usually accumulate more Cd than other crops; therefore, serious concerns have been raised about human health risks resulting from food webs through Cd鄄contaminated rice paddy soils since rice is a staple food source for many Asian countries such as China and India. In hilly regions of southern China, rice plants are often cultivated near forests in a forest鄄 rice agroforestry system, where the forests often occupy the upper parts of the hilly areas and the rice paddy fields are often present in the lower parts and in natural depressions. Although forest鄄rice agroforestry systems have been a typical agricultural model in southern China for many years, the pattern of Cd distribution and cycling and mechanisms controlling its accumulation and transport are still poorly understood in these systems. In this present study, the distribution and dynamic characteristics of Cd were investigated in two types of forest鄄rice agroforestry systems and one rice paddy system (without forests, as a control) in Taoling Forest Farm, Human Province, China from late May to early September in 2012. The concentration and fluxes of Cd in rainfall water, runoff water, pond water, and rice paddy鄄field water were measured.