JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2016, Vol. 40 ›› Issue (02): 21-26.doi: 10.3969/j.issn.1000-2006.2016.02.004

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Hormetic effects of Cr3+, Pb2+ and Cd2+ on nitrate reductase in soils in Chongming Dongtan wetlands

YIN Jie, FAN Diwu, XU Sha, HAN Jiangang*, ZHU Yongli, XUE Jianhui   

  1. Co-Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
  • Online:2016-04-18 Published:2016-04-18

Abstract: The objective of this study is to discover the hormetic effects(a biphasic dose-response characterized by a low dose benefit and a high dose inhibition)between heavy metals and soil enzyme in a typical wetland. Soil samples were taken from Chongming Dongtan, a wetland in the Yangtze River Delta of China. The activities of nitrate reductase(NR)in soils were examined at 0, 6, 12, 24, 48, 72 and 120 hrs incubation in the presence of Cr3+(0.0, 0.5, 5.0, 50.0, 500.0 and 5 000.0 mg/kg), Pb2+(0, 10, 30, 50, 100, 300 and 500 mg/kg)and Cd2+(0.0, 0.1, 1.0, 5.0, 10.0 and 100.00 mg/kg), respectively. Results showed that low dosages of Cr3+(0.5-5.0 mg/kg), Pb2+(10.0 mg/kg)and Cd2+(0.1 mg/kg)significantly enhanced NR activities comparing with that of the control(0.0 mg/kg metal ions added)(P<0.05), showing a typical inverted U-shaped dose-response curve, respectively, which indicated that a hormetic dose-response relationship existed between the three metals and NR in soils. The hormetic effects occurred at time of 6-72 h(Cr3+), 24-120 h(Pb2+)and 6-48 h(Cd2+)incubations, respectively, with the maximum stimulatory response of 56.4%-107.4% greater than the control. Therefore, the hormetic effects imply that the enhanced NR activities possibly affect nitrate reduction in wetland soils. It is very necessary to define and evaluate the effects of low dose heavy metals on soil functions in a wetland in the future.

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