The characterization of humic substances in seawater

Stuermer, Daniel H.

doi:10.1575/1912/1274

Cited by 15 publications

(8 citation statements)

References 110 publications

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“…Recently, the term CDOM has been employed to describe that fraction of the dissolved organic matter which modifies the color of the water by absorption of light (the terms gilvin, gelbstoff, or yellow substance are often used interchangably with CDOM). The oceanographic and limnological literature is rife with reports of the absorption effects of CDOM [James and Birge, 1938;Jerlov, 1955;Kalle, 1961Kalle, , 1966Hojerslev, 1974;Stuermer, 1975;Lundgren, 1976;Kirk, 1976Kirk, , 1980Bricaud et al, 1981;Carder et al, 1989]. Similarly, PDP often has a significant effect on the spectral absorption of ocean particles, especially at short wavelengths [Kiefer and Soohoo, 1982;Kishino et al, 1985;Mitchell and Kiefer, 1988a;Roesler et al, 1989].…”

Section: Spectral Absorption By Degradation Productsmentioning

confidence: 99%

Reflectance model for quantifying chlorophyll a in the presence of productivity degradation products

Hawes²,

et al. 1991

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Marine colored dissolved organic matter (CDOM) (also gilvin or yellow substance) absorbs light at an exponentially decreasing rate as a function of wavelength. From 410 nm to about 640 nm, particulate phytoplankton degradation products including pheopigments, detritus, and bacteria have absorption curves that are similar in shape to that of CDOM. In coastal areas and areas downstream from upwelling regions, these constituents of seawater often absorb much more light than do living phytoplankton, leading to errors in satellite-derived chlorophyll estimates as high as 133%. Proposed NASA sensors for the 1990s will have spectral channels as low as 412 nm, permitting the development of algorithms that can separate the absorption effects of CDOM and other phytoplankton degradation products from those due to biologically viable pigments. A reflectance model has been developed to estimate chlorophyll a concentrations in the presence of CDOM, pheopigments, detritus, and bacteria. Nomograms and lookup tables have been generated to describe the effects of different mixtures of chlorophyll a and these degradation products on the R(412):R(443) and R(443):R(565) remotesensing reflectance or irradiance reflectance ratios. These are used to simulate the accuracy of potential ocean color satellite algorithms, assuming that atmospheric effects have been removed. For the California Current upwelling and offshore regions, with chlorophyll a < 1.3 mg m -3, the average error for chlorophyll a retrievals derived from irradiance reflectance data for degradation product-rich areas was reduced from +61% to +23% by application of an algorithm using two reflectance ratios (R(412) :R(443) and R(443):R(565)) rather than the commonly used algorithm applying a single reflectance ratio (R(443) :R(565)). 1.20,599 20,600 CARDER ET AL.: REFLECTANCE MODEL FOR QUANTIFYING CHLOROPHYLL a tion at 440 nm increased by 60% in 10 days as they tracked a phytoplankton bloom from the Mississippi River plume to Cape San Blas. This widely varying CDOM-to-chlorophyll ratio has a profound effect on upwelled radiance in the blue 443-nm band of the CZCS and a smaller but still significant effect in the green $20-nm band. The correspondence in absorption at 443 nm and 520 nm between CDOM and chlorophyll creates erroneously high estimates of pigment concentration in those models which rely solely upon either of these spectral bands to indicate absorption due to phytoplankton.Separate studies performed in the Southern California Bight point to another way to view the problem. Smith and Baker [1982] developed a pigment algorithm for that site that appears to require a larger absorption effect per unit of chlorophyll-like pigment than do most other case 1 algorithms [see Gordon and Morel, 1983]. However, the algorithm parameters for the Southern California Bight study region changed with time (compare Smith and Baker [1982] to Smith and Wilson [1981]), requiring contemporaneous ship and satellite data for parameter adjustment. Mitchell and Kiefer [1988a] found signifi...

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Section: Spectral Absorption By Degradation Productsmentioning

confidence: 99%

Reflectance model for quantifying chlorophyll a in the presence of productivity degradation products

Hawes²,

et al. 1991

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“…Thus, the UV-absorbing compound isolated in our ether extract appears to be the spawning inducer. However, spawning in nature does not correlate with the abundance of Gelbstoff (yellow substances), since Gelbstoff is largely associated with land drainage (James & Birge 1938, Jerlov 1955, Kalle 1966, Hojerslev 1974, Stuermer 1975, Lundgren 1976, Bricaud et al 1981 and spawning in the St. Lawrence Estuary occurs after the period of major runoff (Starr 1990), thus probably after the Gelbstoff peak. Sieburth & Jensen (1969) indicate that yellow UV-absorbing substances are formed from phenol-like precursors released by F. vesiculosus which are colourless and less absorbing in UV light (270 nm).…”

Section: The Potential Spawning Inducermentioning

confidence: 99%

Isolation and properties of a substance from the diatom Phaeodactylum tricornutum which induces spawning in the sea urchin Strongylocentrotus droebachiensis

Starr¹,

Himmelman²,

Therriault³

1991

Mar. Ecol. Prog. Ser.

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“…Besides these, many other complex organic compounds have been found in the seawater, but their structures are for the moment somewhat hypothetical. Stuermer (1975) and Gagosian and Stuermer (1977) reported that hydrocarbon fragments, amino acids, amino sugars, organic acids, and aromatic rings may be present. According to Hgjerslev (1980), Davies-Colley and Vant (1987) and Carder et al (1989) the compounds of CDOM fall into two main groups: 1) phenolhumic (humic) acids, and 2) carbohydrate humic (fulvic) acids or melanoids.…”

Section: Introductionmentioning

confidence: 99%

“…In the underwater radiation and remote sensing studies not only the spectral absorption coefficient of CDOM throughout the visible range, but also its specific absorption coefficient (which is used to convert the absorption coefficient into the concentration of aquatic humus) is needed. However, only a few investigations have been made with both absorption coefficient and CDOM concentration measurements required for the determination of specific absorption coefficient (data given in Nyquist 1979;Jerlov 1968, Stuermer 1975Hprjerslev 1980;Bricaud et al 1981;Okami et al 1982;Kallio 1999). The values of depend on the composition of CDOM and therefore we cannot expect to obtain one, universal spectrum.…”

Section: Introductionmentioning

confidence: 99%

Optical Properties of Dissolved Organic Matter in Finnish and Estonian Lakes

et al. 2003

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The main objective of the present study is to test various methods for describing the absorption spectra of coloured dissolved organic matter (CDOM) and to determine the numerical values of some optical parameters of CDOM in lakes with diverse water quality. First, the parameters of an exponential model in different spectral intervals were determined. In addition, the suitability of some other models for the approximation of CDOM spectra was estimated. Specific absorption coefficients of CDOM were calculated from the absorption coefficients and dissolved organic carbon (DOC) concentrations. The experimental initial data were differences between spectral attenuation coefficients of filtered and distilled water. Two datasets were used: 1) for 13 Estonian and 7 Finnish lakes (altogether 404 spectra between 350 and 700 nm) measured by the Estonian Marine Institute (EMI); 2) for 10 Finnish lakes (73 spectra) measured by the Finnish Environment Institute (FEI). The spectra of CDOM absorption coefficients (aCDOM) were calculated from experimental data taking into account the correction due to scattering properties of colloids in the filtered water. The total content of CDOM in natural waters of Estonian and Finnish lakes was expressed by means of aCDOM at the wavelength of 380 nm. It varied significantly, from 0.71 to 19.5 m−1, the mean value (of all the investigated lakes) being around 6.6 m−1. Slopes of the exponential approximation varied widely, from 0.006 to 0.03 nm−1. Averaged over all lakes values of slope for the interval 380-500 nm obtained from the EMI dataset are close to those obtained from the FEI dataset: from 0.014 nm−1 (without correction) to 0.016-0.017 nm-1 (with different types of correction). These results are in good correspondence with most published data. Attempts to describe the spectra in the region of 350-700 nm by means of hyperexponential functions (∽ exp(-αλη)) show that: (1) η < 1 (in the case of traditional exponential approximation η = 1); (2) a promising idea is to seek the best fit only for wavelengths λ > λ1, where λ1 will be chosen taking into account the real shape of aCDOM spectra. The mean value of the specific absorption coefficient (a*CDOM) at the wavelength 380 nm obtained in this study (0.44 L mg−1 m−1) is close to the values published in the literature, if we assume that a*CDOM (380) is calculated using the data of dissolved organic matter (DOM). The optically non-active fraction of DOM in our study was high and therefore a*CDOM (380) was considerably higher (1.01 L mg−1 m−1) than a*CDOM (380). The results of the present work could be used in the modeling of underwater light field as well as in the interpretation of radiation measurements and optical remote sensing results.

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The characterization of humic substances in seawater

Cited by 15 publications

References 110 publications

Reflectance model for quantifying chlorophyll a in the presence of productivity degradation products

Reflectance model for quantifying chlorophyll a in the presence of productivity degradation products

Isolation and properties of a substance from the diatom Phaeodactylum tricornutum which induces spawning in the sea urchin Strongylocentrotus droebachiensis

Optical Properties of Dissolved Organic Matter in Finnish and Estonian Lakes

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