Abstract
The accumulation of heavy metals, especially cadmium (Cd), in leafy vegetables was compared with other vegetables. Pak choi (Brassica campestris L. ssp. chinensis) is a leafy vegetable consumed in Taiwan and its safety for consumption after growing in contaminated soils is a public concern. A pot experiment (50 days) was conducted to understand the dynamic accumulation of Cd by pak choi grown in artificially contaminated soils. The edible parts of pak choi were sampled and analyzed every 2–3 days. The dry weight (DW) of pak choi was an exponential function of leaf length, leaf width, and chlorophyll content. The accumulation of Cd increased when the soil Cd concentration was raised, but was kept at a constant level during different growth stages. Pak choi had a high bioconcentration factor (BCF = ratio of the concentration in the edible parts to that in the soils), at values of 3.5–4.0. The consumption of pak choi grown in soils contaminated at levels used in this study would result in the ingestion of impermissible amounts of Cd and could possibly have harmful effects on health.
Highlights
Soils contaminated with heavy metals (HMs) are major environmental problems throughout the world due to their adverse ecological effects
The initial total Cd concentration in soil was 0.8 ± 0.3 mg kg−1, which is less than the SCS of 5.0 mg Cd kg−1 imposed for farmlands in the SGWPR Act of Taiwan and can be regarded as a non-contaminated soil
When growing in Cd-contaminated soils, the total amount of Cd accumulated in the edible parts of pak choi increased because the estimated leaf area (LA) and dry weight (DW) increased, the Cd concentrations did not change drastically
Summary
Soils contaminated with heavy metals (HMs) are major environmental problems throughout the world due to their adverse ecological effects. Paddy rice grown in these soils accumulated high concentration of Cd in their grains [12]. Contaminated sites should conduct necessary remediation practices when their total concentrations (aqua regia soluble) of HMs are beyond those recommended in the SCSs. For farmlands, the SCS for Cd is 5.0 mg kg−1. Many studies have been conducted to investigate the accumulation of Cd in harvest-ready leafy vegetables grown in soils with different Cd concentrations. The main objectives of this study are: (1) to understand the dynamic accumulation of Cd by pak choi, and (2) to assess the risk of uptake of Cd at different growth stages in pak choi grown in soils with different contamination levels of Cd
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