Abstract:
Objective Variations in accumulating PCNB and Cd of different species of vegetables grown on a contaminated soil were studied.
Method In a pot experiment, growth and pollutant absorption/accumulation of Lactuca sativa (CL), L. sativa var. longifolia (RL), Brassica rapa subsp.chinensis (PC), Raphanus sativus (RR), and L. sativa var. angustata (AL) on a PCNB-Cd contaminated soil was monitored.
Result Light and medium levels (i.e., 0.44-6.74 mg·kg-1) of PCNB pollution on the soil stimulated growth of the leafy vegetables tested. However, when the contamination reached the severe level at 9.88-9.96 mg·kg-1, the growth was significantly inhibited. And all levels of the contamination were detrimental to growth of the root vegetables. Cd pollution at between 0.35 mg·kg-1 and 1.96 mg·kg-1 cut the biomass production on all 5 vegetables. In combination, PCNB at 0.47-9.88 mg·kg-1 and Cd at 0.46-1.63mg·kg-1 resulted in varied effects on the vegetable growth. The PCNB contents in the leaves of CL, RL, PC, and AL grown on the severely contaminated soil exceeded the food safety threshold, but the roots of RR and stems of AL did not. Meanwhile, Cd in AL leaves significantly rose to a level surpassing the standard by 60 times, which was followed by the level in the stems of AL and that in the roots of RR. Overall, PCNB absorbed by the vegetables or part of the plants ranked as AL leaves>PC>AL stems>RL>CL>RR, and Cd in the order of AL leaves> AL stems>RR> PC>CL>RL (P<0.05, n=5).
Conclusion The soil contaminated with PCNB-Cd did not significantly affect the absorption of the pollutants individually by the vegetables. In general, L. sativa and L. sativa var. longifolia accumulated PCNB and Cd less than the other tested vegetables making them more suitable for farming on lands moderately polluted with PCNB-Cd.