Zn、Cd单一及复合污染对黑麦草根分泌物及根际Zn、Cd形态的影响

采用根袋土培试验，研究了锌、镉单一及复合污染对重金属富集植物黑麦草生长、锌镉积累、根分泌物及根际Zn、Cd形态的影响.结果表明，锌镉共存下(8 mmol/kg Zn+2 mmol/kg Cd)，黑麦草对锌、镉的吸收为协同效应；仅镉污染时(2 mmol/kg Cd)，镉对植株吸收锌为抑制效应.黑麦草吸收的锌、镉主要集中在地上部，以锌、镉复合污染时植株地上部对锌、镉的富集量最大，分别达到3 108.72、73.97 mg/kg，具有作为土壤重金属锌、镉污染植物修复材料的潜力.根际的松结合态锌、镉（交换态、碳酸盐结合态和铁锰结合态）含量大于其非根际的松结合态锌、镉含量.Cd污染和Zn、Cd复合污染的根际和非根际土壤镉形态均以交换态>碳酸盐结合态>铁锰结合态>残渣态>有机结合态.Zn污染及Zn、Cd复合污染根际和非根际土壤各锌形态以铁锰结合态>碳酸盐结合态>残渣态>有机结合态>交换态，而Cd污染的根际和非根际的锌形态则以残渣态>铁锰结合态>有机结合态>碳酸盐结合态>交换态.Zn、Cd污染促进了黑麦草根系氨基酸的分泌，降低了根际土壤的pH值，以Zn、Cd复合污染根际土壤氨基酸总量最大，分别为对照、Zn和Cd污染的1.95、1.54和1.40倍，根际土壤的pH值最低(5.18).根际氨基酸含量在重金属胁迫下明显增加，可能与黑麦草适应重金属胁迫有关.根际pH值高于非根际是根际Zn、Cd有效性大于非根际的重要原因.

Effects of Individual and Combined Pollution of Cd and Zn on Root Exudates and Rhizosphere Zn and Cd Fractions in Ryegrass (Loliurn perenne L.)

Pot experiments (root rag method) were carried out to investigate the influence of individual and combined pollution of cadmium (Cd) and zinc (Zn) on plant growth, Zn and Cd accumulation in ryegrass (Loliurn perenne L.), rhizosphere Zn and Cd fractions. The results showed that the synergistic effect on uptake between Zn and Cd was observed in the Zn and Cd existing concurrently treatment(8 mmol/kg Zn and 2 mmol/kg Cd) while Zn uptake by ryegrass deceased in the Cd alone treatment(2 mmol/kg Cd). Zn and Cd were distributed mainly in shoot. The highest Zn and Cd concentrations (3 108.72, 73.97 mg/kg, respectively) were found with the combined Zn and Cd treatment and this trait could be beneficial in the selection of high Zn accumulator for soil Zn phytoremediation. The results show that ryegrass has a high potential for soil Zn phytoremediation. The concentrations of Zn fractions (EXC, CAB and FeMn) in rhizosphere were higher than that of bulk soil. Rhizosphere and bulk soil Cd fractions were in the order of EXC > CAB > FeMn > RES > OM in Cd alone and Cd and Zn combined treatments. Rhizosphere and bulk soil Zn fractions were in the order of FeMn > CAB > RES > OM > EXC in Zn alone and Cd and Zn combined treatments, while the order was RES > FeMn > OM > CAB > EXC in Cd only treatment. The concentrations of amino acids increased and soil rhizosphere pH decreased with alone Cd, Zn and combined Cd and Zn treatments. The maximum amino acids concentration was found in the combined Cd-Zn treatment which was approximately 1.95, 1.54 and 1.40 times compared to concentration in the control, Zn and Cd individual treatments, respectively. The minimum of soil pH (5.18) in rhizosphere was found in the combined Cd and Zn treatment.