Yellow Substance Concentrations Research Articles

Spatial-Temporal Regularities of Hydrooptical Characteristics of the Ob River

Field studies conducted in spring (March 26 — April 9, 2022) and summer (June 5-16, 2022) in the Ob River mouth region at the three hydromorphological stations „Kazym-Mys“, „Azovy“, and „Salemal“ (YaNAO) to obtain new data on the hydrooptical characteristics of water in the Lower Ob river. Also, the trophic status and ecological state of the Lower Ob river region were assessed. The greatly varying light attenuation coefficient ε(λ) was calculated at the four characteristic wavelengths of 430, 450, 550, and 670 nm, respectively. It ranges from 9.3 m-1 to 22.1 m-1 during the winter low water (freeze-up) period and from 7.3 m-1 to 33.0 m-1 during the open water (high water) period. The calculated relative spectral contributions of major optically active components of water (pure water, suspension, yellow substance, chlorophyll) to ε(λ) suggest that suspension and yellow substance make up the maximal contribution at different horizons. Additionally, the calculated coefficient of light absorption by yellow substance кys(λ) varies within the ranges from 5.5 m-1 to 9.9 m-1 (spring) and from 3.1 m-1 to 17.0 m-1 (summer), respectively. The relative transparency was measured using the Secchi disc. The concentrations of yellow substance and major photosynthetic pigments — chlorophylls a, b, c, and carotenoids — were estimated alongside. The obtained results could be useful for environmental monitoring and predicting the dynamics of aquatic ecosystems in the region under climate change and increased anthropogenic pressure caused by the use of natural resources.

MAPPING COLOURED DISSOLVED ORGANIC MATTER IN MANILA BAY USING SENTINEL-3 AND WASI

Abstract. Manila Bay is one of the most significant bodies of water in the Philippines; it has abundant natural resources that have been the source of livelihood and center of socio-economic development for centuries. However, Manila Bay is affected by multiple environmental problems and challenges. These include increased organic and nutrient loading from untreated domestic, industrial, and agricultural wastes and deterioration of marine habitats threatened by anthropogenic activities. Regular water quality monitoring is ideal in these situations, however, sampling by traditional field methods would not be enough to assess the spatial and temporal variation of water quality in Manila Bay. Gathering field data for the whole bay can also be very challenging due to its extent and logistic constraints. Remote sensing fills the need for a frequent full view of Manila Bay’s water quality. This study makes use of existing bio-optical models to estimate colored dissolved organic matter (CDOM) in Manila Bay. CDOM is the mixture of organic molecules from decayed higher plants, algae, and bacteria, and is the colored portion of the total dissolved organic matter. Sentinel-3 images with concurrent field sampling on 19 July 2021 was used to calibrate and validate the bio-optical models implemented in WASI. The parameterization output showed an R2 = 0.579 and RMSE of 1.274 m−1 from lab-measured CDOM fluorescence converted to absorption. The same parameter set was used on a different image with a concurrent water quality survey on 19 May 2021 and resulted to an R2 of 0.72 with the spectrofluorometer yellow substance concentrations.

Optical characteristics of water at the mouth of the Ob River

Abstract. As a result of the field studies (August 25 September 1, 2020), new data were obtained on the optical characteristics of water at the Ob River mouth near the Salemal village (Yamal region, Yamal-Nenets Autonomous Okrug) during the lowest water level and the maximum development of hydrobiocenoses. We calculated the light attenuation coefficient ( ) in the spectral range from 400 to 800 nm, which varied from 1.5 to 21.5 m 1 during the study period, and the light absorption by yellow substance ys( ) from 0.1 to 12.2 m 1. Concentrations of yellow substance Cys and chlorophyll Chl were determined. For instance, chlorophyll concentrations in water samples taken at different stations of the Ob River ranged from 12.5 to 22.7 mg m 3. The maximum content of chlorophyll in our case was recorded at a depth of 14 m (station 5.3), which was 22.7 mg m 3. The yellow substance concentration determined optically by the calculated yellow substance light absorption coefficient at wavelength =450 nm ranged within 18.8 and 26.9 g m 3 with an average value of 22.1 g m 3. The average value of ys( ) at =450 nm over the study period was 4.7 m 1.

Spectral light absorption by yellow substance and its dynamics in the surface layers of thermokarst lakes of the Central Yamal

The article presents the experimental data on dynamics of light absorption by yellow substance in the surface layer of 52 thermokarst lakes of the Middle Yamal obtained during hydrological, hydrobiological and hydrochemical field investigations in September 2018. In the study period, light absorption by yellow substance in the spectral range 400–700 nm was calculated as 0.7–0.9 m–1. We measured concentrations of yellow substance Сys and chlorophyll a Chla. The latter had its maximum equal to 12.5 mg/m3. Thirty-seven out of fifty-two samples showed 10.0–14.5 mg/m3 thus corresponding to oligo-and mesotrophic reservoirs. Eutrophic samples (Chla >30 mg/m3) were not registered. Maximum chlorophyll (18.8 mg/m3) was detected in site 52. Concentrations of yellow substance in lakes (2.3–19.3 g/m3) were defined with the use of the optical method due to the measured coefficient of light absorption by yellow substance at a wavelength of λ=450 nm. The correlation between Chla and Сys concentrations in all samples indicated that a low content of chlorophyll (Chla <10 mg/m3) was randomly accompanied by a wide range of attenuation Сys (from 0.5 to 3.0 g/m3), whereas its high concentrations – similarly, by random but significantly less variation of Сys (from 1.1 to 1.9 g/m3).

Spatial variability of hydrooptical characteristics of Lake Teletskoye

The paper presents the results of studies of the spatial distribution of primary hydrooptical characteristics, in particular, light attenuation ε by lake water at a wavelength of 550 nm, light absorption by yellow substance κys at a wavelength of 450 nm, and relative transparency Z measured with Secchi disk. The data were obtained in summer 2018 during field surveys of the Laboratory of Hydrology and Geoinformatics of IWEP SB RAS on Lake Teletskoye (Altai Mountains). The values of ε for the study period were within 0.4–2.3 m–1, κys – 0.5–3.0 m–1 (calculated at natural logarithm base), Z – 1.0–11.7 m. The yellow substance concentration calculated by the measured transmittance of yellow substance, varied within 2.6–14.1 g/m3, the chlorophyll concentration – 0.4–1.8 mg/m3. According to the data from the chemical analytical center of IWEP, the average concentration of total phosphorus in the surface layer of the lake during the study period was 10.8 mg/m3, total nitrogen – 731.3 mg/m3, total carbon – 3.35∙103 mg/m3. Besides, the relative spectral contribution of major optically active components of lake water (purewater, yellow substance,suspended matter and chlorophyll) to light attenuation across the lake water area was estimated. It was found that yellow substance makes the largest contribution to ε at all sampling points (22) of the lake. It is shown that the optical structure of the lake and the spatial variability of hydro-optical characteristics are closely related to the hydrological regime of the lake, meteorological conditions in the region and various optically active water components, whose concentration changes both in time and space under the influence of processes inside the lake in association with the catchment. The analysis of the spatial distribution of the indices of light attenuation and absorption by yellow substance in the lake water showed that Lake Teletskoye stands out not only for its hydro-optical characteristics, but also its hydrobiological and hydrochemical characteristics. Hence, the total light attenuation by lake water can serve as an objective marker of the hydrophysical structure of the lake and its ecological state.

Variability in the Index of Light Absorption by a Yellow Substance in the Surface Layer of Lake Teletskoye

Experimental data obtained in summer 2017 in the course of field hydrophysical studies on the variation in the index of light absorption by a yellow substance in the surface layer of Lake Teletskoye (Altai Mountains) are presented. The calculated values of the index of light absorption by a yellow substance (in natural logarithms) in the spectrum range 400–800 nm during the period under study were within 0.1–2.1 m–1. The yellow substance concentration in Lake Teletskoye, found according to the optical method by the measured index of light absorption by the yellow substance, varied within 2.9–5.1 g/m3. To estimate the effect of light absorption by the yellow substance on the total attenuation, the relative spectral contribution of main optically active lake water components (yellow substance, suspended matter, chlorophyll, and clean water) to the spectral absorption index over the water body under study has been calculated. It has been revealed that the yellow substance makes the maximum contribution at all points (in total, 21 sampling points) of the lake.

Applications of Remote Sensing in Satellite Oceanography: A Review

Remote sensing has got wide range of applications in the field of coastal engineering, including estimation of sea surface temperature, chlorophyll content, suspended sediment concentration, yellow substance concentration, wave characteristics, potential fishing zone (PFZ) and so on. Various satellite remote sensing data has provided rea data which can be used to monitor coastal resources. The present paper gives an overview of some of the applications of remote sensing in the field of satellite oceanography. From the present review, it can be conclude that, even though IR and microwave radiometers can be used for measuring temperatures at different depths in oceans, better choice is to use microwave data as it has got the advantage of penetrating through clouds and also it gives a clear view in all weather conditions except rain. Band ratio approach can be used for identifying different water quality parameters. In recent past, satellite remote sensing has become an ideal tool for identifying Potential fishing zone (PFZ).

Seasonal variability in inherent optical properties in a western Norwegian fjord

We present measured seasonal variations in the inherent optical properties (the absorption and scattering coefficients) of water in a deep silled fjord (Samnangerfjorden) in western Norway. These were based on measurements taken at monthly intervals during an annual cycle. The measurements also include concentrations of chlorophyll a and yellow substance, which were assumed to dominate the behaviour of the absorption and scattering coefficients. The stations were at three fixed locations, one being placed in the innermost part of the fjord where there is little mixing of fjord water with water from the coastal current. The other two stations were placed at different distances from the mouth of the fjord, so that the water masses are characterized by different amounts of mixing between fjord water and coastal current water. Our data set shows how the absorption and scattering coefficients vary in a Norwegian fjord during an annual cycle, and how they depend on the concentrations of chlorophyll a and yellow substance. Values of the absorption coefficient at 412 nm varied between 0.1 and 2.0 m , and scattering coefficients were also found to vary within this range. Little variation over the spectral range was found for the scattering coefficients, but the absorption coefficient had larger spectral variations. The chlorophyll a concentrations varied from 0.01 to 6.3 mg m , and the concentration of yellow substance, as expressed by its absorption coefficient at 310 nm, was within the range 0.7–7.8 m .

Parameterization and analysis of the optical absorption and scattering coefficients in a western Norwegian fjord: a case II water study.

Based on statistical analyses of optical properties measured during a whole year of monthly cruises in a Norwegian fjord, we constructed a two-component model for the absorption and scattering coefficients for visible light. The input to the model is the concentrations of yellow substance and chlorophyll a. Because of the presence of a significant amount of nonalgal particles in coastal water, we assume that the absorption and scattering coefficients approach constant background values when the concentration of chlorophyll a approaches zero. The model works reasonably for a variety of optical conditions encountered throughout the year, with a possible exception during a bloom of the Emiliania huxleyi algae in June.

Optical Properties of a Region of Freshwater Influence (The Clyde Sea)

Optical and associated measurements from eight stations in the Clyde Sea are presented. There is a large range of the diffuse attenuation coefficient, from a minimum of 0·14m−1for green light in the outer stations to 3·65m−1for blue light at the most inshore station in the Clyde Estuary. The reason for this gradient of attenuation is, in part, the presence of high concentrations of yellow substance at the inshore stations. Twenty-five samples of yellow substance analysed had absorption coefficients which decayed exponentially with wavelength: the mean decay constant being −0·018nm−1. The yellow substance is introduced in the freshwater runoff from the land: the evidence for this is the strong negative relationship between yellow substance and salinity. The presence of salinity (and hence yellow substance) stratification produces observable changes in the attenuation of light at the halocline. Attenuation by particulate material is of lesser importance overall but must be accounted for to produce an accurate model of light attenuation in the Clyde Sea. An r.m.s. (root mean square) difference of 0·08m−1between observed and predicted attenuation coefficients is achieved using values of specific particulate absorption from the literature. A simple model of the ratio of reflectance coefficients in water whose optical properties are dominated by yellow substance is proposed. According to this the ratio of reflection coefficients in the red and one other colour should increase linearly with yellow substance concentration. The linear fit should be best if the other colour is chosen in the blue end of the spectrum. This theory is supported by the small data set presented here, and this implies that yellow substance and hence salinity, could be remotely sensed from space in these waters.

Regional and seasonal differences in light absorption by yellow substance in the Southern Bight of the North Sea

Absorption spectra (250–800 nm) of yellow substance were measured in 1993 and 1994 along five onshore–offshore transects in the Southern Bight of the North Sea in different seasons. All spectra had a common shape, so the amount of yellow substance could be established using one reference wavelength as a proxy variable. The exponential slope parameter at 380 nm ( S) of the absorption spectra ranged from −0.016 to −0.023 per nm when regression was based upon the 250–650 nm wavelength range; values were 25% lower when fitting was performed over the more restricted waveband 360–540 nm, partly due to a minor shoulder at 260–275 nm in all spectra. The concentration of yellow substance, expressed as the absorption coefficient at 380 nm ( a 380; m −1), varied over an order of magnitude, from low values down to 0.17 m −1 in the English Channel, up to 1.00–1.25 m −1 near the Rhine and Scheldt outflow, to maxima of up to 1.75 m −1 in the neritic–estuarine waters at the entrance to the shallow Wadden Sea. This regional distribution pattern was in agreement with the known water-mass circulation and with the location of sources of yellow substance: highest concentrations close to the shore under the influence of freshwater inflow, lower values with increasing distance from the coast, where Atlantic Ocean water is the major water-mass component. No significant seasonal variation in yellow-substance concentration was found anywhere when a correction was applied for salinity. Extrapolation to zero salinity yielded an absorption coefficient at 380 nm of 5.38 m −1 for the freshwater input at both the Texel and Walcheren transects, but of 3.29 m −1 at the Noordwijk transect, reflecting differences in yellow-substance concentration between the Rhine, the Meuse, and Lake IJssel, as previously noted in fluorescence measurements. Yellow-substance concentration was not only correlated with salinity but also, albeit much less, with chlorophyll concentrations; the contribution of phytoplankton to the yellow-substance pool was marginal but significant. A relation appeared to exist between yellow-substance absorbance at 380 nm and yellow-substance fluorescence intensity; fluorescence measurements in the southern North Sea can be translated to absorption (more appropriate for ocean colour detection by remote sensing) by equating 1 mFl unit to an absorption coefficient at 380 nm of 0.056 m −1, and using the exponential relation a ys( λ)= a ys( λ ref)exp(− S( λ− λ ref)) for extrapolation to UV–Vis spectral absorption.

Remote sensing of water quality in the Singapore-Johor-Riau growth triangle

Remote sensing has not been used extensively in southeast Asia for resource development, partly for reasons of perennial cloud cover and low image availability. However, the low level of awareness of remote sensing among planning and environmental agencies is unjustified in view of the capabilities of high spatial and spectral resolution sensors such as the Landsat Thematic Mapper (TM), coupled with a general lack of physical resources data throughout the region. The main objective of this study is to demonstrate the application of Landsat MT imagery to the survey and monitoring of water quality in coastal regions affected by land drainage from peat swamp catchments, which are common in southeast Asia, thus where dissolved organic matter (yellow substance) dominates the volume reflectance of coastal water. The Thematic Mapper 0.45–0.52 μmv waveband was found to be capable of differentiating water with high concentration of yellow substance from nonplume water, but the addition of the 0.63–0.69 μm waveband was required for differentiating lower concentrations of yellow substance. The higher temperature of yellow substance dominated river plumes observed on the 10.5–12.5 μm waveband confirmed field observations. These findings have implications for water resource management in the region, since image derived classes of water quality can be related to environmental standards for the main types of water use.

Yellow substance in coastal and marine waters round the South Island, New Zealand

Abstract Yellow substance, the single largest component of dissolved organic matter in natural waters, is often the most important blue‐light‐absorbing constituent. The spectral absorption of yellow substance was measured by spectrophotometry in coastal (including fiord) and marine waters round toe South Island of New Zealand on Cruise 2027 (May 1989) of the RV Rapuhia; this examined a wide range of optical variables in relation to primary productivity and water mass characteristics. The spectral absorption by yellow substance fitted an exponential model, as is typical, and the spectral slope parameter varied only slightly (mean = 0.015 nm−1, standard deviation = 0.002 nm−1 ) for oceanic waters in the range 300–460 nm. The concentration of yellow substance, indicated by the absorption coefficient of filtrates at 440 nm (g440), varied more than two orders of magnitude, from 0.014 m−1 in the cold subantarctic water south‐east of the South Island, to 1.8 m−1 in humic‐stained surface water in Doubtful Sound. In marine waters, g440 was fairly tightly distributed around a mean of 0.06 m−1 ‐a value typical in sea waters. g440 did not correlate with phytoplankton pigment content of marine waters, probably because most of the yellow substance was old material, derived from terrestial production or long past marine production. Nor was g440 correlated with salinity. But there was a weak (probably incidental) correlation with temperature (r = +0.57), with higher values of yellow substance in the relatively warm waters along the South Island west coast than in the colder waters off the east coast. The concentration of yellow substance explained nearly half of the total variation in light (PAR) absorption at the stations visited.

Sun-stimulated chlorophyll fluorescence 1: Influence of oceanic properties

Abstract A series of radiative transfer calculations is performed to study the potential of using Sun-stimulated chlorophyll fluorescence for the detection of phytoplankton. Calculated radiance spectra including the fluorescence peak agree well with measurements. We found that the Sun-stimulated natural fluorescence of chlorophyll-a is a good predictor for phytoplankton, even in waters with varying suspended matter and yellow substance concentrations. An increase in chlorophyll concentration of 1 mg m−3 causes an increase in fluorescence of about 0·05Wm−2sr−1μm−1, when a fluorescence efficiency factor of 0·3 per cent was assumed. The vertical stratification of chlorophyll affects the fluorescence signal, for example, the fluorescence is reduced to 30 per cent, if the phytoplankton is below 2 m depth instead of reaching the water surface.

A COMPARATIVE STUDY OF IRRADIANCE, BEAM TRANSMITTANCE AND SCATTERING IN THE SEA NEAR BERMUDA1

Comparative measurements of a number of optical properties of the sea were made at 6 stations and at depths down to 245 m near Bermuda. In situ determinations included attenuation of natural radiant energy and reflectance between 375 and 651 mµ, beam transmittance and scattering, as well as polarization 90° to the beam. In the laboratory, scattering and degree of polarization were determined at 90° from water samples, while scattering was also measured at 45° to the beam. Both photovoltaic cells and photomultipliers were used as required.The irradiance and beam transmittance data indicate that the wide differences in attenuation at different stations are primarily due to variations in the amount of suspended matter both offshore and inshore provided that the coastal or partly enclosed water is in open communication with the sea. However, in Harrington Sound, which has only restricted communication with open water, the optical properties differ in indicating greater concentrations of yellow substance than at any other station. Scattering coefficients measured at 45° and 90° in the laboratory show an approximately linear correlation for Castle Harbour and North Shore stations. In general the scattering coefficients at 90° are systematically correlated with the degree of polarization so that plotting p‐log β yields a linear function whose slope depends on the nature of the particles suspended in the different water masses.In situ measurements of scattering and polarization usually were different from those in the laboratory. In clear Sargasso Sea water, for instance, in situ polarization was greater (75–80%) than it was in the laboratory (60%) although the scattering coefficients in the sea were definitely smaller. Further work is required to account for such discrepancies. Comparisons of in situ polarization of natural radiant energy with polarization from a light beam show that natural polarization decreases more rapidly than that from an artificial light beam as the amount of scattering increases. This effect results from the dependence of submarine polarization not only on scattering but also on directionality of the underwater radiant energy which diminishes for daylight with the amount of suspended matter.