There was no significant relationship (p N 0.05) between the BAF of
OrgHg in roots and the respective BAF for IHg, which confirms that
OrgHg has different accumulation mechanisms when compared with
IHg. Furthermore, the BAF for OrgHg in roots is not constant.
Hence, to assess which variables are responsible for the variability
of BAFs we tested the relationship between the BAF for OrgHg in
roots (log-transformed values) and the concentration of IHg in
soils; the concentration of OrgHg in soils; soil properties (including
pH, OrgC and clay); and the concentration of IHg in roots, by linear
regression analysis. Results showed that the levels of IHg in soils and
soil properties do not significantly affect the accumulation of OrgHg in
roots (p N 0.05) suggesting that the variation in the availability of
OrgHg in soil in association with soil properties is not the main factor
controlling its accumulation in roots. The linear regression model
(Rodrigues et al., 2012b) that best describes the variability of BAF for
OrgHg in roots is the following: