Screening of cost-effective soil amendments is important to develop “in situ” remediation techniques for cadmium (Cd) contaminated soils. In this study, different soil amendments, including red mud, a by-product of the alumina industry, and acid-treated, nano-treated by nano-particle milling, nano and acid-treated red muds, zeolite, corn straw, and rape straw, were evaluated to immobilize Cd in two added levels (2 and 5 mg Cd·kg-1 soil) in a calcareous soil by single and sequential extractions and by cucumber (Cucumis sativus L.) pot experiments. Results indicated that cruciferous rape straw significantly decreased the concentrations of water soluble, extractable Cd in soils, and Cd in cucumber plants, and it was more effective than gramineous corn straw. Also, red mud generally decreased the extractability and bioavailability of Cd added to calcareous soils more effectively than zeolite. Furthermore, the efficiency of red mud could be increased by the treatment of nano-particle milling due to the increase in specific surface area of red mud. It is potential to use rape straw and red mud as soil amendments to develop a cost-effective and efficient “in situ” remediation technology for Cd mildly contaminated calcareous soils. 相似文献
The phytotoxicity of added copper (Cu) and nickel (Ni) is influenced by soil properties and field aging. However, the differences in the chemical behavior between Cu and Ni are still unclear. Therefore, this study was conducted to investigate the extractability of added Cu and Ni in 6-year field experiments, as well as the link with their phytotoxicity. The results showed that the extractability of added Cu decreased by 6.63% (5.10%–7.90%), 22.5% (20.6%–23.9%), and 6.87% (0%–17.9%) on average for acidic, neutral, and alkaline soil from 1 to 6 years, although the phytotoxicity of added Cu and Ni did not change significantly from 1 to 6 years in the long term field experiment. Because of dissolution of Cu, when the pH decreased below 7.0, the extractability of Cu in alkaline soil by EDTA at pH 4.0 could not reflect the effects of aging. For Ni, the extractability decreased by 18.1% (10.1%–33.0%), 63.0% (59.2%–68.8%), and 22.0% (12.4%–31.8%) from 1 to 6 years in acidic, neutral, and alkaline soils, respectively, indicating the effects of aging on Ni were greater than on Cu. The sum of ten sequential extractions of Cu and Ni showed that added Cu was more extractable than Ni in neutral and alkaline soil, but similar in acidic soil.
It is an important approach to use the Cd-contaminated soils properly by growing low accumulator or excluder plants for Cd to
produce safe foods. To find the suitable vegetable species for growing in Cd-contaminated soils, in the present study the variations in
the Cd accumulation for twenty eight vegetable species and several cultivars of five common vegetables (cowpea, kidney pea, bitter
gourd, cucumber and squash) were investigated in two soil Cd levels (1 and 2 mg/kg Cd). Experimental results showed that highly
significant di erences in Cd concentration were evident among 28 vegetables. For example, spinach Cd concentrations were 110-fold
and 175-fold higher than that of sweet pea under the 1 and 2 mg/kg Cd exposures, respectively. For Cd accumulation, the order of
vegetable species was: leafy vegetables > solanaceous vegetables > kale vegetables > root vegetables > allimus > melon vegetables >
legumes. Distinctive di erences were also identified when comparing di erent cultivars of the five common vegetables with an average
range of 0.003–0.094 mg/kg Cd. Our results indicated that a large genotypic variation existed among vegetable species or cultivars
when subjected to Cd exposure. Therefore, it is important and feasible to elect/breed vegetable species/cultivars with low accumulation
of Cd, especially in mildly Cd-contaminated soils. 相似文献