Using 67Cu to study the biogeochemical cycling of copper in the northeast subarctic Pacific Ocean
| Autor: | Katherine A. Barbeau, Marie Robert, Anna M. Posacka, Maria T. Maldonado, David M. Semeniuk, Randelle M. Bundy |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
0106 biological sciences
Biogeochemical cycle 010504 meteorology & atmospheric sciences lcsh:QH1-199.5 chemistry.chemical_element Ocean Engineering Biology Aquatic Science lcsh:General. Including nature conservation geographical distribution Photosynthesis ligand Oceanography 01 natural sciences Line P iron Phytoplankton Trace metal Marine Science 14. Life underwater Transect lcsh:Science 0105 earth and related environmental sciences Water Science and Technology Remineralisation Global and Planetary Change northeast subarctic Pacific Ocean 010604 marine biology & hydrobiology Copper organic ligands Iron limitation chemistry 13. Climate action Environmental chemistry uptake Seawater lcsh:Q heterotrophic bacteria |
| Zdroj: | Frontiers in Marine Science, Vol 3 (2016) |
| ISSN: | 2296-7745 |
| Popis: | Microbial copper (Cu) nutrition and dissolved Cu speciation were surveyed along Line P, a coastal to open ocean transect that extends from the coast of British Columbia, Canada, to the high-nutrient-low-chlorophyll (HNLC) zone of the northeast subarctic Pacific Ocean. Steady-state size fractionated Cu uptake rates and Cu:C assimilation ratios were determined at in situ Cu concentrations and speciation using a 67Cu tracer method. The cellular Cu:C ratios that we measured (~30 µmol Cu mol C-1) are similar to recent estimates using synchrotron x-ray fluorescence (SXRF), suggesting that the 67Cu method can determine in situ metabolic Cu demands. We examined how environmental changes along the Line P transect influenced Cu metabolism in the sub-microplankton community. Cellular Cu:C assimilation ratios and uptake rates were compared with net primary productivity, bacterial abundance and productivity, total dissolved Cu, Cu speciation, and a suite of other chemical and biological parameters. Total dissolved Cu concentrations ([Cu]d) were within a narrow range (1.46 to 2.79 nM), and Cu was bound to a ~5-fold excess of strong ligands with conditional stability constants ( ) of ~1014. Free Cu2+ concentrations were low (pCu 14.4 to 15.1), and total and size fractionated net primary productivity (NPPV; µg C L-1 d-1) were negatively correlated with inorganic Cu concentrations ([Cu′]). We suggest this is due to greater Cu′ drawdown by faster growing phytoplankton populations. Using the relationship between [Cu′] drawdown and NPPV, we calculated a regional photosynthetic Cu:C drawdown export ratio between 1.5 and 15 µmol Cu mol C-1, and a mixed layer residence time (2.5 to 8 years) that is similar to other independent estimates (2-12 years). Total particulate Cu uptake rates were between 22 and 125 times faster than estimates of Cu export; this is possibly mediated by rapid cellular Cu uptake and efflux by phytoplankton and bacteria or the effects of grazers and bacterial remineralization on dissolved Cu. These results provide a more detailed understanding of the interactions between Cu speciation and microorganisms in seawater, and present evidence that marine phytoplankton modify Cu speciation in the open ocean. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|