However, DOM generally reduces copper toxicity, and DOM in natural
waters is therefore beneficial to reduce harmful effects of copper. At
concentrations of 3.8 and 6 mg DOC/L, copper neurotoxicity to juvenile
Coho salmon (at a dissolved Cu concentration of 20 μg/L) was reduced
by 50% and 100%, respectively (McIntyre et al., 2008). These DOC concentrations
are higher than what was present in our stormwater
(0.4 mg DOC/L), but lower than in our bioretention systems leachates
(30–1370 mg DOC/L). Consequently, any copper leaching from the
bioretention systems should be much less toxic to aquatic organisms
than inorganic copper ions