Oxygen minimum zones (OMZs) in the ocean are of key importance for pelagic fixed-nitrogen loss (N-loss) through microbial denitrification and anaerobic ammonium oxidation (anammox). Recent studies document that zooplankton is surprisingly abundant in and around OMZs and that the microbial community associated with carcasses of a large copepod species mediates denitrification. Here, we investiga...

Figure 1. Wavelength-dependent light intensity at different water depths (indicated by numbers assigned to contour lines). Light intensity is given in percent of surface light intensity, where 100% equals ~30,000 lux (~600 mmol quanta m22 s21), estimated to be 24 h average expected for light intensity on horizontal surface on clear summer day (Thimijan and Heins, 1983). Contour lines were deriv...

The U/U isotopic composition of uranium in seawater can provide important insights into the modern U budget of the oceans. Using the double spike technique and a new data reduction method, we analyzed an array of seawater samples and 41 geostandards covering a broad range of geological settings relevant to low and high temperature geochemistry. Analyses of 18 seawater samples from geographicall...

Patterns of sedimentary trace-metal variation can provide information not only about benthic redox conditions, but also about other water-mass properties in ancient marine depositional systems. Trace metals such as Mo, U, V, and Re display conservative concentration profi les in the global ocean but varying concentration profi les in modern anoxic silled basins (e.g., the Black Sea, Cariaco Bas...

Abstract Aptian to Campanian sediments from the Western offshore Central Orange Basin were studied by integrating molecular geochemistry, inorganic and isotopic studies recognize their geochemical characteristics via reconstruction of basin’s paleoweathering, paleosalinity, paleovegetation, paleoclimate, tectonic records. Molecular analyses both aliphatic aromatic compounds reveal an input domi...

Iron (Fe) and copper (Cu) are essential cofactors for microbial metalloenzymes, but little is known about the metalloenyzme inventory of anaerobic marine microbial communities despite their importance to the nitrogen cycle. We compared dissolved O2, NO[Formula: see text], NO[Formula: see text], Fe and Cu concentrations with nucleic acid sequences encoding Fe and Cu-binding proteins in 21 metage...

Rubisco I's specificity, which today may be almost perfectly tuned to the task of cultivating the global garden, controlled the balance of carbon gases and O(2) in the Precambrian ocean and hence, by equilibration, in the air. Control of CO(2) and O(2) by rubisco I, coupled with CH(4) from methanogens, has for the past 2.9 Ga directed the global greenhouse warming, which maintains liquid oceans...