Long term impacts of heavy metals on soil microbial diversity, numbers and function

Lead Research Organisation: Rothamsted Research
Department Name: Unlisted


Objectives : 1) To investigate the effect of long-term heavy metals (Zn, Cu) exposure on microbial population size, diversity and function in soils, using a range of well-equilibrated field soils from long-term sewage sludge experiments and from transects around galvanised structures. 2) To determine the relationship between genetic diversity of particular functional groups (e.g. generalised carbon cycling pseudomonads, nitrifers and rhizobia) and their resilience to heavy metal stress. The hypothesis tested is whether soils with low or high diversity are more or less affected by stress. 3) To investigate the relationship between soil metal concentrations or metal speciation and microbial measurements, including microbial numbers, diversity and function. Soil microbes are responsible for providing essential ecosystem services and they include some of the most sensitive groups that will influence future soil protection legislation to guard against unsustainable metal accumulations in soil. We will focus on three contrasting bacterial groups which have important functions in soils and determine the relationships between their population size, diversity and functions, and environmental exposure. We will use a range of recent molecular (q-PCR, 16S rRNA, DGGE, specific functional gene primers, BrdU incorporation for native population analyses) and conventional techniques to quantify the numbers, diversity and function of these groups across gradients of chronic Zn and Cu exposure, derived from unique field experiments. Chemical measurements of soils and soil solutions and the latest speciation modelling methods will be employed to determine the environmental exposure associated with the microbiological changes. Our results will be used to provide a scientific basis for national and European agricultural and environmental policies related to protection of ecosystem services and sustainable practices.


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