Chromium speciation in seawater: The probable role of hydrogen peroxide

Abstract

Abstract-The rates of oxidation of Cr(III) to Cr(V1) with H,O, were measured in NaClO, solutions as a function of pH, temperature, ionic strength, and H,O, concentration.

The speciation and physico-chemical forms of metals in surface waters and sediments

“…Compounds of chromium(VI) are dominant in well oxygenated waters, with a fairly low organic matter content and a pH close to 8. But in waters of pH 5.0 -7.0, where levels of easily reducible organic substances are high, the dominant species are those of chromium(III) (Pettine et al, 1990).…”

Diurnal and seasonal distribution of hydrogen peroxide in seawater of the Seto Inland Sea.

“…Johnson et al (1989) proposed that the H202 produced by the photochemical reaction can be used as a tracer for vertical advection in the western Mediterranean Sea. However, ver tical advection in regard to the H202 distribution in the Seto Inland Sea seems to be rather weak in June due to (1) the stratospheric period in this time and (2) shallow depth less than 50 m, which There are various factors to diminish H202 such as metal ions (Moffet andZika, 1987b, Pettine andMillero, 1990), diffusion (advection) and coexistent organic substances. However, the biological activities seem to be most important to control the diel H202 distribution.…”

“…9. In this case, the samples collected in the points closer to the estuary gave larger amounts of the generatable Metal ions such as Cu", H', and N20 become the species to react with hydrated elec tron (Power et al, 1987, Frimmel et al, 1987, Pettine and Millero, 1990, Telser and Schindewoif, 1986 besides DO. Addition of ED TA at the concentration of 0.25 M improves the correlation coefficient (r) to 0.870 for the samples observed in Fig.…”

The comparative cytotoxicity and genotoxicity of hexavalent chromium in humans and sea turtles.

“…Chromium (Cr) is a metal that is found naturally in the Earth's crust and which has many desirable properties such as its hardness, resistance to corrosion, and bright colors [10]. It is widely used in many applications such as a coloring agent for paints and dyes, chrome plating, leather tanning, an anticorrosive agent for boats, aircraft, and military equipment, and it is a component of alloys used in joint replacement prosthetics [11,12].…”

“…Hazardous compounds released from the sediments may suspend in the water column where leatherback sea turtles, a pelagic species, spend a majority of their time [28]. In addition to being released from ocean sediments Cr(VI) is also released into the environment through the burning of fossil fuels and other industrial processes [10,[29][30][31]. Ultimately Cr(VI) released in this manner can travel through air currents around the world with the potential to settle in the oceans.…”