LEAD SPECIATION IN SURFACE WATERS OF THE EASTERN NORTH PACIFIC.

Titrations using differential pulse anodic stripping voltammetry (DPASV) to detect electroactive lead were carried out on fresh seawater samples and on samples stored acidified to determine the extent of lead complexation in the eastern North Pacific. Results of these analyses on surface water samples indicate total dissolved lead concentrations between 17 and 49 pM. The inorganic or DPASV labile fraction is 30–50%. Titration with lead yielded data consistent with one class of organic ligand(s), present at low concentration (between 0.2 and 0.5 nM) with a mean value for a conditional stability constant with respect to inorganic lead of log K′cond=9.7. The presence of this ligand, together with the various inorganic ligands in seawater, gives rise to a concentration of free ionic lead of ∼ 0.4 pM

Ocean iron fertilization - moving forward in a sea of uncertainty

The consequences of global climate change are profound, and the scientific community has an obligation to assess the ramifications of policy options for reducing greenhouse gas emissions and enhancing CO2 sinks in reservoirs other than the atmosphere

A synthesis of mesoscale iron-enrichment experiments 1993-2005: key findings and implications for ocean biogeochemistry

info:eu-repo/semantics/publishe

Mesoscale iron enrichment experiments 1993-2005: synthesis and future directions

Since the mid-1980s, our understanding of nutrient limitation of oceanic primary production has radically changed. Mesoscale iron addition experiments (FeAXs) have unequivocally shown that iron supply limits production in one-third of the world ocean, where surface macronutrient concentrations are perennially high. The findings of these 12 FeAXs also reveal that iron supply exerts controls on the dynamics of plankton blooms, which in turn affect the biogeochemical cycles of carbon, nitrogen, silicon, and sulfur and ultimately influence the Earth climate system. However, extrapolation of the key results of FeAXs to regional and seasonal scales in some cases is limited because of differing modes of iron supply in FeAXs and in the modern and paleo-oceans. New research directions include quantification of the coupling of oceanic iron and carbon biogeochemistry