Miguel Izaguirre

The oxidation kinetics of Fe(II) in seawater

Abstract The oxidation of Fe(II) has been studied as a function of pH (5 to 9), temperature (5 to 45°C), and salinity (0 to 35). The pseudo-first-order rate constant, k1, −d[Fe(II)] dt = k 1 [Fe(II)] in water and seawater was found to be a second degree function of pH over the pH range of 7.5 to 8.5 at 5°C and 6.0 to 8.0 at 25°C. The overall rate constant (k) −d[Fe(II)] dt = k[Fe(II)][O 2 ][OH − ] 2 was determined from 5 to 45°C and S = 0 to 35. The results have been fit to an equation of the form (T = 273.15 + t°C) log k = log k 0 − 3.29I 1 2 + 1.52I where logk0 = 21.56–1545/T with a standard error = 0.09. The energy of activation for the overall rate constant in water and seawater was 29 ± 2 kJmol−1. The values of the rate constant for pure water (k0) are in good agreement with literature data. The half times for seawater from some previous studies at a pH = 8.0 were slower than our results for Gulf Stream waters. Measurements on Biscayne Bay waters also yield slower half times apparently due to the presence of organic ligands that can complex Fe(II).

Chemical and physical characteristics of nascent aerosols produced by bursting bubbles at a model air‐sea interface

inorganic aerosol constituents were similar to those in ambient air. Ca 2+ was significantly enriched relative to seawater (median factor = 1.2). If in the form of CaCO3, these enrichments would have important implications for pH-dependent processes. Other inorganic constituents were present at ratios indistinguishable from those in seawater. Soluble organic carbon (OC) was highly enriched in all size fractions (median factor for all samples = 387). Number size distributions exhibited two lognormal modes. The number production flux of each mode was linearly correlated with bubble rate. At 80% RH, the larger mode exhibited a volume centroid of 5-mm diameter and included 95% of the inorganic sea-salt mass; water comprised 79% to 90% of volume. At 80% RH, the smaller mode exhibited a number centroid of 0.13-mm diameter; water comprised 87% to 90% of volume. The median mass ratio of organic matter to sea salt in the smallest size fraction (geometric mean diameter = 0.13 mm) was 4:1. These results support the hypothesis that bursting bubbles are an important global source of CN and CCN with climatic implications. Primary marine aerosols also influence radiative transfer via multiphase processing of sulfur and other climate-relevant species.

Effect of ionic strength and ionic interactions on the oxidation of Fe(II)

AbstractThe rates of oxidation of Fe(II) in NaCl and NaClO4 solutions were studied as a function of pH (6 to 9), temperature (5 to 25°C), and ionic strength (0 to 6m). The rates are second order with respect to [H+] or [OH−] and independent of ionic strength and temperature. The overall rate of the oxidation is given by

The effect of ionic interaction on the rates of oxidation in natural waters

d[Fe(II)]/dt = - k[Fe(II)][OH^ - ]^2 [O_2 ]

A Microbolometer Airborne Calibrated Infrared Radiometer: The Ball Experimental Sea Surface Temperature (BESST) Radiometer

where [OH−]=KW*/[H+](KW* is the stoichiometric dissociation constant for water) and [O2] is the molal concentration of the oxygen. The experimental results were fitted to equations of the form

Vertical distributions of dust and sea‐salt aerosols over Puerto Rico during PRIDE measured from a light aircraft

log{\text{ }}k = log{\text{ }}k_0 + {\rm A}\sqrt {\rm I} + {\rm A}\sqrt {\rm I} /T + CI