This is similar to what was observed for soil organic carbon. In fact
there is a significant positive correlation between IHg and soil organic
carbon (r = 0.85, p b 0.01). The main factor contributing to the distribution
of IHg in soils is therefore not the distance to the primary Hg
source but the pattern of distribution of soil organic carbon along the
former effluent stream. For soils located at 300–500 m away from
“Vala de S. Filipe” (sites 10 to 13), IHg levels were considerably lower
and below 0.70 mg kg−1 d.w. indicating IHg levels decrease rapidly
with distance from the stream.