Chemical and biological methods to evaluate the availability of heavy metals in soils of the Siena urban area (Italy).
A biogeochemistry field study was conducted in the Siena urban area (Italy) with the main objective of establishing the relationship between available amounts of heavy metals in soil assessed by a chemical method (soil fractionation) and bioavailability assessed by a biological method (bioaccumulation in earthworm tissues). The total content of traffic-related (Cd, Cu, Pb, Sb, Zn) and geogenic (Co, Cr, Ni, U) heavy metals in uncontaminated and contaminated soils and their concentrations in soil fractions and earthworms were used for this purpose. The bioavailability of heavy metals assessed by earthworms did not always match the availability defined by soil fractionation. Earthworms were a good indicator to assess the bioavailability of Pb and Sb in soil, while due to physiological mechanisms of regulation and excretion, Cd, Cu and Zn tissue levels in these invertebrates gave misleading estimates of their bioavailable pool. No relationship was identified between chemical and biological availability for the geogenic heavy metals, characterized by a narrow range of total contents in soil. The study highlighted that chemical and biological methods should be combined to provide more complete information about heavy element bioavailability in soils.
Department of Environmental, Earth and Physical Sciences, University of Siena, Via del Laterino 8, I-53100 Siena, Italy. Electronic address: nannoni@unisi.it.
Francesco
F
Nannoni
Department of Environmental, Earth and Physical Sciences, University of Siena, Via del Laterino 8, I-53100 Siena, Italy.
Giuseppe
G
Protano
D000818:Animals; D001682:Biological Availability; D005591:Chemical Fractionation / Q000379:methods*; D002947:Cities; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods*; D007558:Italy; D019216:Metals, Heavy / Q000032:analysis / Q000378:metabolism*; D009835:Oligochaeta / Q000378:metabolism*; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D001335:Vehicle Emissions / Q000032:analysis
D019216:Metals, Heavy; D012989:Soil Pollutants; D001335:Vehicle Emissions
Biological availability; Chemical availability; Earthworms; Heavy metals; Soil fractionation; Urban area