Sunlight photolysis engenders release of dissolved copper from resuspended coastal marine sediments from diverse biogeochemical settings and locations. In nine of 14 experiments, using environmentally relevant sediment concentrations (100-300 mg/L), net Cu photorelease over 6 h was 4 to >40 nmol/g dry sediment, increasing dissolved Cu by 0 to 11.8 nM. Release of Cu significantly correlated with sediment Cu content. Longer term experiments (12-24 h) showed continued release of Cu that was not readsorbed back onto sediment suggesting that organic complexation may stabilize photoreleased Cu. Experiments also show that dissolved organic carbon is produced with a concomitant increase in UV-vis absorbance (254 and 300 nm) of suspensions through at least 24 h of irradiation. Photolytic fluxes of dissolved Cu are similar in magnitude to both riverine and benthic fluxes and may represent a previously unrecognized, episodic source of this micronutrient metal to coastal waters.

Photolytic release of dissolved copper and dissolved organic carbon from resuspended coastal marine sediments

245th National Meeting (2013)

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