Effect of dissolved NaCl, MgCl_2, and Na_2SO_4 in seawater on the optical attenuation in the region from 430 to 630 nm

Ravisankar, M.; Reghunath, A. T.; Sathianandan, K.; Nampoori, V. P. N.

doi:10.1364/ao.27.003887

Cited by 19 publications

(7 citation statements)

References 11 publications

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“…The reason for the difference is presented later in this paper. Our results are presented together with earlier results 10,11 in Fig. 7.…”

Section: Salinity Measurementssupporting

confidence: 86%

“…As was the case with temperature there has been little research done in studying the role of salinity on the optical properties of water at visible wavelengths. 10,11 This study spans the wavelength regions covered in the previous studies to provide a more comprehensive understanding of the effects of dissolved salt on the absorption coefficient. By changing the concentration of salt incrementally we show how the absorption coefficient depends on salinity over a wide range of naturally occurring salinities.…”

Section: Introductionmentioning

confidence: 99%

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Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity

1997

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We have measured the absorption coefficient of pure and salt water at 15 wavelengths in the visible and near-infrared regions of the spectrum using WETLabs nine-wavelength absorption and attenuation meters and a three-wavelength absorption meter. The water temperature was varied between 15 and 30 degrees C, and the salinity was varied between 0 and 38 PSU to study the effects of these parameters on the absorption coefficient of liquid water. In the near-infrared portion of the spectrum the absorption coefficient of water was confirmed to be highly dependent on temperature. In the visible region the temperature dependence was found to be less than 0.001 m-1 degrees C except for a small region around 610 nm. The same results were found for the temperature dependence of a saltwater solution. After accounting for index-of-refraction effects, the salinity dependence at visible wavelengths is negligible. Salinity does appear to be important in determining the absorption coefficient of water in the near-infrared region. At 715 nm, for example, the salinity dependence was -0.00027 m-1 /PSU. Field measurements support the temperature and salinity dependencies found in the laboratory both in the near infrared and at shorter wavelengths. To make estimates of the temperature dependence in wavelength regions for which we did not make measurements we used a series of Gaussian curves that were fit to the absorption spectrum in the visible region of the spectrum. The spectral dependence on temperature was then estimated based on multiplying the Gaussians by a fitting factor.

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“…The reason for the difference is presented later in this paper. Our results are presented together with earlier results 10,11 in Fig. 7.…”

Section: Salinity Measurementssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity

1997

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“…Additionally, aqueous solutions of other major ionic species in seawater besides Na ϩ and Cl Ϫ have been shown to be colorless in the visible. 5 Finally, recent measurements with a capillary waveguide system with a 2 m path length detected no significant absorption in the visible in the dissolved fraction of seawater from the surface of the ultraclear South Pacific Ocean after purified NaCl solution blank corrections were applied. 25 This observation verifies that there is no inorganic substance that can be considered a universal component of seawater that exhibits significant (i.e., measurable at this time) absorption in the visible.…”

Section: ϫmentioning

confidence: 93%

Hyperspectral temperature and salt dependencies of absorption by water and heavy water in the 400-750 nm spectral range

Sullivan

Twardowski²,

Zaneveld³

et al. 2006

Appl. Opt.

213

160

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The temperature and salt dependencies of absorption by liquid water (H2O) and heavy water (D2O) were determined using a hyperspectral absorption and attenuation meter (WET Labs, AC-S). Sodium chloride (NaCl) was used as a proxy for seawater salts. There was no significant temperature (PsiT) or salt (PsiS) dependency of absorption at wavelengths <550 nm. At wavelengths >550 nm, PsiT exhibited peaks at approximately 604, 662, and 740 nm. A small negative trough in PsiS occurred at approximately 590 nm, followed by a small positive peak approximately 620 nm, a larger negative trough at approximately 720 nm, and a strong positive peak at approximately 755 nm. The salt dependency of absorption by heavy water, Psis(H), exhibited a negative power-law shape with very low Psis(H), at wavelengths >550 nm. Our experiments with NaCl, clean open ocean seawater, and artificial seawater support the hypothesis that salts modify the absorption spectra of seawater by modifying the molecular matrix and vibrations of pure water.

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“…The major element, Fe, was spread over the surface uniformly. The presence of elements such as Na, Mg and Cl is indicated by constituents of seawater such as NaCl and MgCl 2 [19]. Oxygen spread over the surface of the steel indicates the presence of corrosion products of oxide film.…”

Section: Element Distribution Of Corroded Surface After Exposurementioning

confidence: 99%

Corrosion Behavior of Mild Steel in Seawater from Northern Coast of Java and Southern Coast of Bali, Indonesia

Sundjono

Priyotomo

Nuraini

et al. 2018

J. Eng. Technol. Sci.

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Abstract. The corrosion behavior of mild steel in seawater was investigated using an immersion test and energy-dispersive X-ray spectroscopy in solutions from the sites of Muara Baru, Suramadu and Tol Mandara. As reference, solutions of 3.5% and 5% NaCl were prepared. Dissolved oxygen, salinity, conductivity, and total dissolved solids (TDS) were measured. It was found that uniform corrosion occurred on the mild steel during the immersion test. The corrosion resistance of the steel decreased with increasing exposure time. Since the magnitudes of conductivity, salinity and TDS of all test solutions were similar, it was concluded that dissolved oxygen (DO) and chloride ions play an essential role in inducing the corrosion risk of mild steel. Both parameters hinder the formation of a stable passive film on the surface of corroded mild steel.

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Effect of dissolved NaCl, MgCl_2, and Na_2SO_4 in seawater on the optical attenuation in the region from 430 to 630 nm

Cited by 19 publications

References 11 publications

Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity

Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity

Hyperspectral temperature and salt dependencies of absorption by water and heavy water in the 400-750 nm spectral range

Corrosion Behavior of Mild Steel in Seawater from Northern Coast of Java and Southern Coast of Bali, Indonesia

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