Incorporation of radioactive adenine into DNA has recently been used as a measure of total microbial production in marine environments, sometimes with unexpected results. We have examined two of the assumptions on which the method is based, particularly regarding the distribution of adenine uptake and nucleic acid content in mixed natural microbial assemblages. Size fractionation, autoradiograp...

Eddies play a critical role in regulating the biological pump by pumping new nutrients to the euphotic zone. However, the effects of cyclonic eddies on particle export are not well understood. Here, biogenic silica (BSi) and particulate organic carbon (POC) exports were examined inside and outside a decaying cyclonic eddy using 234Th-238U disequilibria in the tropical South China Sea. For the e...

Based on the optical properties of water constituents, vertical variation photosynthetically available radiation (PAR) can be well modeled with hyperspectral resolution; intensive computing load, however, demands simplified modeling that easily embedded in marine physical and biogeochemical models. While PAR profile homogeneous waters now accurately simple parameterization, it is still a big ch...

changes in abundance and biomass of cyanobacteria have been studied in the southern part of the caspian sea (the stretch between tonekabon and amirabad) in four seasons (spring, summer, autumn, winter) in which samples were taken from five depths of 5, 10, 20, 50 and 100 meters in the stations of tonekabon, noushahr, babolsar and amirabad. samples were fixed in formalin (2-2.5%) before transfer...

We report in situ rates of gross oxygen production (GOP), community respiration (R), and net (NCP) the North Pacific Subtropical Gyre derived from mixed layer O2/Ar measurements. The measurements were conducted between November 2013 January 2019 at site Hawaii Ocean Time-series program. Biological O2 concentration anomalies showed a consistent diel variation, with values increasing during dayti...

A 6-compartment biogeochemical model of nitrogen cycling and plankton productivity has been coupled with a 3D general circulation model in an enclosed environment (the Black Sea) so as to quantify and compare, on a seasonal and annual scale, the typical internal biogeochemical functioning of the shelf and of the deep sea as well as to estimate the nitrogen and water exchanges at the shelf break...

We examined the spatial distributions of picoplankton, nanoplankton, and microplankton biomass and physiological state relative to the hydrography of the Southern Ocean along 90 degrees W longitude and across the Drake Passage in the late austral winter. The eastern South Pacific Ocean showed some large-scale biogeographical differences and size class variability. Microbial ATP biomass was grea...