Accumulation Properties of Cadmium in a Selected Vegetable-Rotation System of Southeastern China

Abstract

A rotation experiment was conducted in a greenhouse with three vegetable crops on red yellowish soil (RYS) and silt loamy soil (SLS) to study Cd accumulation in pak choi ( Brassica chinensis L.), tomato ( Lycopersicon esculentum), and radish ( Raphanus sativus L.). Critical Cd concentrations in the two soils were evaluated for these vegetables based on human dietary toxicity. Cadmium was added as Cd(NO 3) 2 at a rate of 0-7.00 mg Cd kg (-1) soil. Shoot growth was not inhibited by Cd except for radish grown on RYS. A small amount of Cd stimulated growth of the vegetables. Cadmium concentration in edible parts of the vegetables generally increased with Cd concentration in soils but was higher in RYS than SLS. The distribution of Cd in pak choi and tomato decreased in the order root > shoot > fruit, but the order was shoot > root for radish. When Cd content in the edible parts reached maximum contaminant levels for safety food standards, the soil total Cd concentrations were 0.327 and 0.120 mg kg (-1) in RYS and 0.456 and 0.368 mg kg (-1) in SLS for pak choi stem and radish, respectively, whereas ammonium acetate-extractable Cd was 0.066 and 0.089 mg kg (-1) in RYS and 0.116 and 0.092 mg kg (-1) in SLS for pak choi leaf and tomato, respectively, based on food safety standards.

Lead accumulation in different Chinese cabbage cultivars and screening for pollution-safe cultivars

“…1). Although Cd and Pb are nonessential toxic elements to plant growth, some researchers found similar positive and neutral responses of plant biomass to heavy metal stress in a broad range of crop species (Xie and Huang, 1994;Zhu et al, 2007;Shentu et al, 2008;Liu et al, 2009a,b,c). Therefore, farmers may not get timely and sufficient warning of the uptake of toxic heavy metals based on the apparent growth of these crop cultivars (Zhu et al, 2004).…”

“…However, mechanism of the positive and neutral responses of plants to pollution stress has not been fully understood. One possible reason may be that metal ions may serve as activators of enzyme(s) in cytokinin metabolism, which accelerates the growth of plants (Kaminek, 1992;Shentu et al, 2008). Therefore, further studies should be carried out to completely explore the positive and neutral responses of plant biomass to heavy metal stress.…”

Assessment of heavy metal pollution in vegetables and relationships with soil heavy metal distribution in Zhejiang province, China

“…Soil pH was measured using 1:2.5 (w/v) soil/de-ionized water ratio. For determination of total Cd, Pb, Cr, As, and Hg in soil, portions of each 0.20 g of soil samples were digested with HNO 3 -HClO 4 -HF (5:1:1) (Shentu et al 2008). These soil properties are listed in Table 1.…”

Effect of Biochar Amendment on Bioavailability and Accumulation of Cadmium and Trace Elements in Brassica chinensis L. (Chinese Cabbage)

“…For the determination of total Cd and trace metals (Fe, Mn, Zn) concentration in soil, 0.2 g of each soil sample was digested with HNO 3 -HF-HClO 4 (5:1:1) (Shentu et al, 2008). Whereas, for plant samples 0.2 g of dried tissue of each treatment was digested in 15 mL HCl/HNO3 /HClO 4 (3:1:2 v/v) at 150 °C until the solution became clear.…”