Microbial community structure and activity in trace element-contaminated soils phytomanaged by Gentle Remediation...

Area of Science:

• Environmental Science
• Soil Science
• Microbiology

Background:

• Trace element contaminated soils (TECS) pose risks to ecosystem functions.
• Gentle remediation options (GRO), integrating plants, microbes, and amendments, offer a sustainable approach.
• Understanding GRO's impact on soil biology is crucial for effective remediation.

Purpose of the Study:

• To evaluate the effects of three GRO strategies on soil microbial biomass, respiration, enzyme activities, and bacterial community structure in TECS.
• To assess the influence of GRO on key functional genes involved in nitrogen cycling.
• To elucidate the role of soil properties and trace element availability in site-specific responses to phytomanagement.

Main Methods:

• Field trials across Europe implementing aided-phytostabilisation, in situ stabilisation and phytoexclusion, and aided-phytoextraction.
• Analysis of soil microbial biomass (ATP), soil respiration, and hydrolase enzyme activities (C, N, P, S cycling).
• Bacterial community structure analysis using denaturing gradient gel electrophoresis (DGGE) and gene-specific quantitative PCR (qPCR) for nitrogen cycling genes.

Main Results:

• Phytomanagement increased soil microbial biomass at three sites and respiration at the Biogeco site (France).
• Enzyme activities were consistently higher in treated soils, with significant increases at the Biogeco site (2-11 fold).
• GRO induced shifts in bacterial community structure and generally increased nitrogen cycling genes (nirK, nirS, nosZ, amoA).

Conclusions:

• Phytomanagement strategies effectively enhance soil biological activity in trace element contaminated soils.
• GRO positively influences microbial biomass, respiration, enzyme function, and nitrogen cycling.
• Site-specific factors, including soil properties and trace element availability, modulate the effectiveness of phytomanagement.