OWH and OP exhibited the highest DOC values (expressed in
percentage, for better comparison with the TOC values) among
the materials tested, which is related to their high HA and FA contents
(DOC and FA contents were correlated with a regression coefficient
of 0.94) and the presence of labile organic compounds, such
as polysaccharides or simple peptides in both materials (Zmora-
Nahum et al., 2007), that are able to interact with heavy metals
to form soluble chelates.