Little is known about the trace metal content of marine prokaryotes, in part due to their co‐occurrence with more abundant particulate phases in the upper ocean, such as phytoplankton and biogenic detritus, lithogenic minerals, and authigenic Mn and Fe oxyhydroxides. We attempt to isolate these biomass signals in particulate data from the US GEOTRACES Eastern Pacific Zonal Transect (cruise GP16) in the Eastern Tropical South P...

Arsenic and phosphorus are biochemically very similar, and hence arsenate (As 5+ ) is toxic by interfering with the energy metabolism, in particular during P limitation. However, many phytoplankton detoxify As by reducing arsenate to arsenite (As 3+ ), and/or methylating it to mono and dimethyl As. Such As detoxification becomes operative in oligotrophic waters when phosphate concentrations are below those for As; therefore, w...

The cycling of the radiatively important gas carbonyl sulfide (OCS) was studied in surface waters of the Sargasso Sea. In August 1999, surface OCS concentrations averaged 8.6 pmol L −1 , showed minor diel variations, and varied little with depth. An OCS precursor, total dissolved organic sulfur (DOS), was lowest at the surface (40 nmol L −1 ) and increased with depth. The photoproduction rate of OCS from in situ incubations av...

The potentially toxic element selenium is first concentrated from solution to a large but highly variable degree by algae and bacteria before being passed on to consumers. The large loads of abiotic and detrital suspended particles often present in rivers and estuaries may obscure spatial and temporal patterns in Se concentrations at the base of the food web. We used radiotracers to estimate uptake of both selenite (Se(IV)) an...

Se is present in multiple oxidation states in nature, each of which has unique chemical and biological reactivities. As a consequence, the rate of Se incorporation into food webs or its role as either a limiting nutrient or a toxic substance is a function of complex biogeochemistry. In particular, little is understood about the accumulation of dissolved organic selenides by phyto‐ or bacterioplankton. We assessed the bioavaila...