Heavy metal availability and impact on activity of soil microorganisms along aCu/Zn contamination gradient
WANG Yuan-peng , SHI Ji-yan , LIN Qi , CHEN Xin-cai , CHEN Ying-xu
DOI:
Received August 16, 2006,Revised January 04, 2007, Accepted , Available online
Volume 19,2007,Pages 848-853
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All the regulations that define a maximum concentration of metals in the receiving soil are based on total soil metal concentration.
However, the potential toxicity of a heavy metal in the soil depends on its speciation and availability. We studied the e ects of heavy
metal speciation and availability on soil microorganism activities along a Cu/Zn contamination gradient. Microbial biomass and enzyme
activity of soil contaminated with both Cu and Zn were investigated. The results showed that microbial biomass was negatively a ected
by the elevated metal levels. The microbial biomass-C (Cmic)/organic C (Corg) ratio was closely correlated to heavy metal stress.
There were negative correlations between soil microbial biomass, phosphatase activity and NH4NO3 extractable heavy metals. The soil
microorganism activity could be predicted using empirical models with the availability of Cu and Zn. We observed that 72% of the
variation in phosphatase activity could be explained by the NH4NO3-extractable and total heavy metal concentration. By considering
di erent monitoring approaches and di erent viewpoints, this set of methods applied in this study seemed sensitive to site di erences
and contributed to a better understanding of the e ects of heavy metals on the size and activity of microorganisms in soils. The
data presented demonstrate the relationship between heavy metals availability and heavy metal toxicity to soil microorganism along a
contamination gradient.
