Abstract
Heavy metal (HM) pollution is a global environmental problem that threatens ecosystem and human health. Cadmium (Cd) pollution is the most prominent HM pollution type because of its high toxicity, strong migration, and the large polluted area globally. Phytoremediation of contaminated soil is frequently practiced because of its cost-effectiveness and operability and because it has no associated secondary pollution. High-accumulation plants, including those identified as hyperaccumulators, play an important role in phytoremediation. Therefore, screening of plants to identify hyperaccumulators is important for continued phytoremediation. In the present study, we investigated the Cd tolerance and accumulation capabilities of 18 turnip landraces from China under a soil experiment with known Cd level. The results indicated that turnip has a high capacity for Cd accumulation. Furthermore, significant differences in Cd tolerance and accumulation characteristics were found among different landraces when they grew at 50 mg kg-1 (dry weight) Cd concentration. Among the studied landraces, five turnip landraces met the requirements of Cd hyperaccumulators and three landraces were identified as potential candidates. However, the total Cd content accumulated by individual plant of different turnip landraces was dependent on both the Cd accumulation capacity and plant biomass. Compared with some reported Cd hyperaccumulators, turnip not only shows a high Cd-accumulation capacity but also has rapid growth and a wide distribution area. These advantages indicate that turnip may have considerable potential for phytoremediation of Cd-contaminated soil. Furthermore, the study also indicates that it is not advisable to consume turnip cultivated in an environment that exceeds safe Cd levels.
Highlights
Heavy metal (HM) pollution is a global environmental problem, which seriously threatens ecosystem safety, agricultural production and human health (Gao, 2016)
When treated by Cd at different concentrations for 3 weeks, the morphology of turnip plants showed no significant differences compared with the control materials (Figure 1A)
As the Cd concentration added to the soil increased, the Cd content accumulated in the AG part of plants was improved (Figure 1B)
Summary
Heavy metal (HM) pollution is a global environmental problem, which seriously threatens ecosystem safety, agricultural production and human health (Gao, 2016). Soil Cd has three main sources including atmospheric deposition, irrigation with sewage and use of pesticides and chemical fertilizers (Sikka et al, 2009). Enrichment of Cd in soil can change soil physical and chemical properties, reduce the richness, diversity, and activity of soil microorganisms, and inhibit soil respiration, subsequently affecting soil fertility (Zheng and Shang, 2006). The absorbed Cd can poison other organisms, including humans, along the food chain (Amna et al, 2015; Tauqeer et al, 2016). Cd is selectively enriched in the kidney and liver, damaging organ functions (Wu, 2015). Several events of human Cd poisoning resulting from soil Cd pollution have subsequently been reported around the world (Sterckeman et al, 2000; Du et al, 2013)
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