TY - JOUR
T1 - The Biogeochemical Cycling of Iron, Copper, Nickel, Cadmium, Manganese, Cobalt, Lead, and Scandium in a California Current Experimental Study
AU - Mellett, Travis
AU - Brown, Matthew T.
AU - Chappell, P. Dreux
AU - Carolyn Duckham, Carolyn Duckham
AU - Fitzsimmons, Jessica N.
AU - Till, Claire P.
AU - Sherrell, Robert M.
AU - Maldonado, Maria T.
AU - Buck, Kristen N.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - A 3‐day shipboard incubation experiment was conducted in the California Current System in July 2014 to investigate the cycling of iron (Fe), copper (Cu), nickel (Ni), cadmium (Cd), manganese (Mn), cobalt (Co), lead (Pb), and scandium (Sc) under a range of light and particle conditions. Filtered (< 0.2 μm) and unfiltered treatments were incubated under the following light conditions: Dark, light (“UV”), and light without the ultraviolet (UV) wavelengths (“noUV”). The experiment was sampled for carbon and Fe uptake rates, dissolved trace metal concentrations (Fe, Cu, Ni, Cd, Mn, Co, Pb, Sc), Fe and Cu speciation, size‐fractionated concentrations of Cd and Fe, and diatom community composition from DNA sequencing. Exposure to UV light increased phytoplankton Fe uptake in the first 24 h of the incubation relative to the noUV treatment, suggesting that a fraction of the ambient ligand‐bound Fe was photoreactive. Fe‐binding organic ligand production was observed in the unfiltered light treatments in association with increasing chlorophyll a , and evidence for Cu‐binding ligand production in these treatments was also observed. Biological uptake of Cd and Co was observed along with scavenging of dissolved Pb. Manganese appeared to be rapidly oxidized by Mn‐oxidizing bacteria with concomitant drawdown of dissolved Ni. Scandium displayed similar trends to Fe, reinforcing the limited observations of the physicochemical similarities between these two elements in seawater. Overall, this study highlights distinct impacts of photochemical processes, scavenging, and biological effects on marine trace metal cycling in an environment characterized by seasonal upwelling.
AB - A 3‐day shipboard incubation experiment was conducted in the California Current System in July 2014 to investigate the cycling of iron (Fe), copper (Cu), nickel (Ni), cadmium (Cd), manganese (Mn), cobalt (Co), lead (Pb), and scandium (Sc) under a range of light and particle conditions. Filtered (< 0.2 μm) and unfiltered treatments were incubated under the following light conditions: Dark, light (“UV”), and light without the ultraviolet (UV) wavelengths (“noUV”). The experiment was sampled for carbon and Fe uptake rates, dissolved trace metal concentrations (Fe, Cu, Ni, Cd, Mn, Co, Pb, Sc), Fe and Cu speciation, size‐fractionated concentrations of Cd and Fe, and diatom community composition from DNA sequencing. Exposure to UV light increased phytoplankton Fe uptake in the first 24 h of the incubation relative to the noUV treatment, suggesting that a fraction of the ambient ligand‐bound Fe was photoreactive. Fe‐binding organic ligand production was observed in the unfiltered light treatments in association with increasing chlorophyll a , and evidence for Cu‐binding ligand production in these treatments was also observed. Biological uptake of Cd and Co was observed along with scavenging of dissolved Pb. Manganese appeared to be rapidly oxidized by Mn‐oxidizing bacteria with concomitant drawdown of dissolved Ni. Scandium displayed similar trends to Fe, reinforcing the limited observations of the physicochemical similarities between these two elements in seawater. Overall, this study highlights distinct impacts of photochemical processes, scavenging, and biological effects on marine trace metal cycling in an environment characterized by seasonal upwelling.
UR - https://digitalcommons.usf.edu/msc_facpub/554
U2 - 10.1002/lno.10751
DO - 10.1002/lno.10751
M3 - Article
VL - 63
JO - Limnology and Oceanography
JF - Limnology and Oceanography
ER -