关键词: 闪锌矿, 菱锌矿, 生菜, 颗粒态金属

Abstract: The exploitation of zinc mines has led to a continuous influx of metals into soils through mining and smelting, resulting in the risks of excessive metal concentration in crops. Compared with that in non-mining areas, metals in soils around mines mainly exist in particulate form, releasing metal ions and metal-bearing nanoparticles with different bioavailability. With a pot experiment, we investigated the effects of Zn-mineral-derived cadmium (Cd) and Zn from typical zinc (Zn)-sulphide mineral (sphalerite, SP) and -oxy-salt mineral (smithsonite, SM) on the growth of lettuce (Lactuca sativa L.), the available content of Cd and Zn in soil, and Cd and Zn uptake by lettuce. The results showed that: (1) The addition of 0.1% and 1.0% SM significantly inhibited lettuce growth (P<0.05), with a reduction of 81.2% in fresh weight under the latter addition, whereas SP addition had no significant effect on lettuce growth (P>0.05). (2) CaCl₂ and EDTA-extractable Cd and Zn in the soil significantly increased with SM addition but showed no response to SP addition. SM-spiked soils had significantly higher CaCl₂ and EDTA-extractable Cd and Zn concentrations and higher Zn/Cd molar fractions than those in SP-spike soils. (3) The total amount of Cd and Zn in the lettuce shoot increased and decreased with a higher addition amount of Zn mineral in SP and SM-treatment, respectively. The total amount of Cd and Zn in the lettuce shoot of the SM treatment was significantly higher than that of the SP treatment. (4) The results of transmission electron microscopy combined with energy-dispersive X-ray spectroscopy (TEM-EDS) showed that Cd- and Zn-bearing nanoparticles occurred in lettuce shoots under both Zn mineral-spiked treatments. The mechanism underlying the formation of these nanoparticles needs to be considered in further work. This study provides a new perspective for assessing the risk of heavy metal uptake in soil and crops from different lead-zinc mining areas.

Key words: sphalerite, smithsonite, Lactuca sativa L., particulate metal