Specific ultraviolet absorbance (SUVA) is the absorbance of
ultraviolet light
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
in a water sample at a specified wavelength that is normalized for
dissolved organic carbon
Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called particu ...
(DOC) concentration.
Specific UV absorbance (SUVA) wavelengths have analytical uses to measure the aromatic character of dissolved organic matter by detecting density of electron conjugation which is associated with aromatic bonds.
[Bourbonniree, Richard A. 2009. Peat Water Chemistry. Canadian water resources journal. 34(4)]
Derivation
To derive SUVA, first, UVC light (
UV spectrum subtypes) at 254 nm or 280 nm,
is measured in units of absorbance per meter of path length, often the sample must be diluted with
ultrapure water
Ultrapure water (UPW), high-purity water or highly purified water (HPW) is water that has been purified to uncommonly stringent specifications. Ultrapure water is a term commonly used in manufacturing to emphasize the fact that the water is treated ...
because absorbance can be high.
[Chantigny, MH., Angers, DA., Kaiser, K., Kalbitz, K. 2008. Extraction and Characterization of Dissolved Organic Matter. Soil Sampling and Methods of Analysis. MR. Carter (Ed.) Canadian Society of Soil Science, Lewis Publishers, Ann Arbor, MI.] As increasing dissolved organic carbon concentration increases absorbance in the UV range, the UV light has to be normalized to the concentration of
dissolved organic carbon
Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called particu ...
in mg per L to ascertain differences in the aromatic quality of the water.
Aromatic character is used in the study of dissolved organic matter, from mineral soils, or organic soils, to use as an assay to whether or not dissolved organic carbon in the water is labile, a ready source of energy, or is from a relatively old source of carbon (recalcitrant). However, although a good indicator of aromaticity, caution must be used with determination of reactivity.
Measures of water purity often rely on measuring
turbidity
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality.
Fluids can ...
, not aromaticity.
References
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Sources
*Holl BS, Fiedler S, Jungkunst HF, Kalbitz K, Freibauer A, Drosler M, Stahr K. 2009. Characteristics of dissolved organic matter following 20 years of peatland restoration. Science of the Total Environment. 408(1):78-83.
Water chemistry
Spectroscopy