Accumulation, sources and health risks of heavy metals in intensive greenhouse vegetable production system, China

In recent years, greenhouse vegetable production is growing rapidly and makes up a sizeable proportion of vegetable production in China. Heavy metal accumulation in greenhouse soils and vegetables is a growing concern for... [ view full abstract ]

In recent years, greenhouse vegetable production is growing rapidly and makes up a sizeable proportion of vegetable production in China. Heavy metal accumulation in greenhouse soils and vegetables is a growing concern for public health. In this study, 120 surface greenhouse soils and corresponding vegetable samples were collected from three typical intensive greenhouse vegetable production systems in China to systematically evaluate the transfer characteristics, sources and potential health risk of selected heavy metals. Mean concentrations of Cd, As, Hg, Pb, Cu and Zn in greenhouse soils were 0.21, 7.12, 0.05, 19.81, 24.95 and 94.11 mg/kg, dw, respectively. Concentrations of heavy metals in all vegetable samples were decreased in the order of Zn>Cu>Pb>As>Cd>Hg. The sources of heavy metals were mainly from fertilizer application, especially for livestock manure. Compared with rootstalk and fruit vegetables, leafy vegetables had relatively high concentrations and transfer factors of heavy metals, especially for Cd. Accumulation of heavy metals in soils were also affected by soil pH and organic matter. The target hazard quotient (THQ) of heavy metals by consumption of different kinds of vegetables decreased in the order of leafy vegetables>rootstalk vegetables>fruit vegetables, and their risk values were 0.61, 0.33 and 0.26, respectively. The findings of this study suggested that excessive consumption of leafy vegetables grown in the greenhouse posed a relatively greater potential health risks for consumers. The rootstalk and fruit vegetables showed a relatively lower transfer factor and health risks for heavy metals, and therefore they were more suitable for cultivation in greenhouse soils.