MOE Key Laboratory of Western China's Environmental Systems and Gansu Key Laboratory for Environmental Pollution Prediction and Control, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China.
MOE Key Laboratory of Western China's Environmental Systems and Gansu Key Laboratory for Environmental Pollution Prediction and Control, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China.
Sci Total Environ. 2021 Feb 10;755(Pt 1):142535. doi: 10.1016/j.scitotenv.2020.142535. Epub 2020 Sep 28.
Poplar serves as a phytostabilizator in phytomanagement of the trace metals (TMs) copper (Cu) and lead (Pb) contaminated land. In the process of long-term phytomanagement, it is not clear how the cycling of the mineral nutrients calcium (Ca) and sodium (Na) in calcareous soil will affect poplar remediation mechanisms. We selected a site contaminated by Cu and Pb and phytomanaged by Populus simonii Carr. stands of different ages (7, 14, and 28 years) to study the influencing mechanisms. The results showed that after afforestation, the Ca in the subsoil returned to the topsoil through fallen leaves, whereas the Na in the topsoil migrated downward to the subsoil by leaching, resulting in the redistribution of mineral nutrients in the soil profile. In addition, the Ca content in soil solution of the root-zone was significantly lower relative to that of the bulk soil, whereas the Na content in soil solution was significantly higher in all stands. As a result, because of the competitive adsorption of mineral nutrient and TM cations on the soil surface, the pool of bioavailable TM in root-zone soils did not significantly decrease with stand age. On the contrary, the TM content in poplar leaves (Cu: 31-37 mg kg; Pb: 62-84 mg kg) and litter (Cu: 230-790 mg kg; Pb: 394-1366 mg kg) increased significantly with stand age. Nevertheless, the TM content in poplar wood (Cu < 3 mg kg; Pb < 12 mg kg) remained at an extremely low level in all stands. Our results highlighted that strengthening leaf collection is necessary to eliminate ecological risks and ensure the safe production of poplar wood in the long-term phytomanagement of TM-contaminated land.
杨树在受痕量金属（TMs）铜（Cu）和铅（Pb）污染土地的植物管理中用作植物稳定剂。在长期的植物管理过程中，不清楚碳酸钙土壤中矿物质养分钙（Ca）和钠（Na）的循环将如何影响杨树修复机制。我们选择了一个受 Cu 和 Pb 污染并由不同年龄（7、14 和 28 年）的 Populus simonii Carr.林分进行植物管理的地点来研究影响机制。结果表明，造林后，表土中的 Ca 通过落叶返回亚表层，而表土中的 Na 通过淋洗向下迁移到亚表层，导致土壤剖面中矿物质养分的再分布。此外，根区土壤溶液中的 Ca 含量明显低于原状土，而所有林分的土壤溶液中的 Na 含量明显较高。因此，由于矿物质养分和 TM 阳离子在土壤表面的竞争吸附，根区土壤中生物有效 TM 的库没有随林龄显著减少。相反，杨树叶片（Cu：31-37mg kg；Pb：62-84mg kg）和凋落物（Cu：230-790mg kg；Pb：394-1366mg kg）中的 TM 含量随林龄显著增加。尽管如此，所有林分中杨树木材（Cu <3mg kg；Pb <12mg kg）中的 TM 含量仍保持在极低水平。我们的结果强调，加强叶片收集对于消除生态风险并确保在 TM 污染土地的长期植物管理中安全生产杨树木材是必要的。
