Stoichiometry of Multi-Elements in the Zinc-Cadmium Hyperaccumulator Thlaspi Caerulescens Grown Hydroponically under Different Zinc Concentrations Determined by ICP-AES
HAN Wen-xuan, XU Yi-ming, DU Wei, TANG Ao-han, JIANG Rong-feng*
Key Laboratory of Plant-Soil Interactions of Ministry of Education; Key Laboratory of Plant Nutrition of Ministry of Agriculture; College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
摘要： 锌镉超累积植物遏蓝菜(Thlaspi caerulescens)是重要的重金属污染土壤修复植物，但环境Zn浓度是否会影响该植物对其他元素的吸收，进而影响土壤养分的平衡，此前并不清楚。研究采用可同时测量多种元素的ICP-AES技术，分析高、中、低Zn浓度(5，50和500 μmol·L-1)多元素营养液培养的遏蓝菜中Zn, Cd, K, P, Mg, Ca, Fe, Mn, Cu等元素的计量变化特征。结果显示，随着Zn供给浓度的升高，遏蓝菜根和茎叶的Zn含量都显著增加, 高Zn培养的遏蓝菜茎叶和根的Zn含量比低Zn培养条件分别增加12和19倍;但植物茎叶中其他八种元素的含量均无显著变化, 即在应用遏蓝菜修复Zn污染的土壤时，不会造成K, P, Mg, Ca, Fe, Mn, Cu元素从土壤中被植物过量带走而出现养分失衡。
关键词：元素分析;重金属超累积植物;植物修复;元素计量;养分平衡
Abstract：Thlaspi caerulescens is commonly known as a zinc (Zn) and cadmium (Cd) hyperaccumulator, which can be used to clean up the Zn- and/or Cd-contaminated soil. However, it is unclear whether high soil Zn concentrations will stimulate undue accumulations of other elements to such an extent as to cause the nutrient unbalance in the soil. To address this question, the inductively coupled plasma-atomic emission spectrometry (ICP-AES) was employed to investigate the effect of Zn on the stoichiometry of Zn, Cd, K, P, Mg, Ca, Fe, Mn and Cu in T. caerulescens (Ganges ecotype) exposed to low, middle and high Zn concentrations (5, 50 and 500 μmol·L-1, respectively) in a hydroponic experiment. The results showed that there were no significant variations in contents of Cd, K, P, Mg, Ca, Fe, Mn and Cu in the shoot of T. caerulescens, however, the Zn content in the shoot and root with 500 μmol·L-1 Zn treatment increased as much as 13 times higher than that with low Zn exposure, indicating that the plant is capable of Zn hyperaccumulating. The authors’ study suggests that it is improbable to induce soil nutrient unbalance when T. caerulescensis (Ganges) is used for phytoremediation of Zn-contaminated soil, in that over-uptake of nutrient elements from the soil other than Zn was not observed, at least for the elements K, P, Mg, Ca, Fe, Mn and Cu.
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