Pedosphere 15(4): 409--416, 2005
ISSN 1002-0160/CN 32-1315/P
©2005 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Microbial activity indices: Sensitive soil quality indicators for trace metal stress
1 College of Natural Resources and Environment, South China Agricutrual University, Guangzhou 510642 (China). E-mail:
2 UMR 137 Biodiversité et Fonctionnement des Sols, Institut de Recherche Pour le Développement (France)
3 Université Paris Sud XI FRE Orsay Terre 2566 Bat, 504, 91405 Cedex (France)
4 UMR-CNRS 7047, Lab. de Géochimie el Métallogénie/Université Pierre et Marie Curie (France)
      Physicochemical properties, total and DTPA (diethylenetriaminepentaacetic acid)-extractable Cu, Zn, Pb and Cd contents, microbial biomass carbon (C) content and the organic C mineralization rate of the soils in a long-term trace metal-contaminated paddy region of Guangdong, China were determined to assess the sensitivity of microbial indices to moderately metal-contaminated paddy soils. The mean contents of total Cu, Zn, Pb and Cd were 251, 250, 171, and 2.4 mg kg-1 respectively. DTPA-extractablc metals were correlated positively and significantly with total metals, CEC, and organic C (except for DTPA-extractable Cd), while they were negatively and highly significantly correlated with pH, total Fe and Mn. Metal stress resulted in relatively low ratios of microbial biomass C to organic C and in remarkable inhibition of the microbial metabolic quotient and C minera]ization rate, which eventually led to increases in soil organic C and C/N. Moreover, microbial respiratory activity showed a stronger correlation to DTPA-extractable metals than to total metal content. Likewise, in the acid paddy soils some "linked" microbial activity indices, such as metabolic quotient and ratios of basal respiration to organic C, especially during initial incubation, were found to be more sensitive indicators of soil trace metal contamination than microbial biomass C or basal respiration alone.
Key Words:  availability, indication, microbial characteristics, trace metals
Citation: Li, Y. T., Becquer, T., Quantin, C., Benedetti, M., Lavelle, P. and Dai, J. 2005. Microbial activity indices: Sensitive soil quality indicators for trace metal stress. Pedosphere. 15(4): 409-416.
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