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

Author(s):  
A. Manuel ◽  
A. C. Blanco ◽  
O. Cabrera ◽  
M. L. San Diego-McGlone

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.

Fisheries ◽  
2020 ◽  
Vol 2020 (5) ◽  
pp. 25-29
Author(s):  
Anatoliy Sadchikov ◽  
Sergey Ostroumov

The role of algae and bacteria in the consumption and mineralization of dissolved organic matter (DOM) in a highly trophic aquatic ecosystem was studied. The phytoplankton and bacterioplankton community consumed 60% of added DOM in August and 56% of DOM in September. Of the uptaken DOM, a significant amount of organic carbon was mineralized. In August 42.7% and in September 29% of organic carbon (of the consumed organic matter) were used for respiration.


2015 ◽  
Vol 12 (23) ◽  
pp. 6999-7011 ◽  
Author(s):  
P. Glaz ◽  
J.-P. Gagné ◽  
P. Archambault ◽  
P. Sirois ◽  
C. Nozais

Abstract. Forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. Water quality and fluorescence characteristics of dissolved organic matter (DOM) were measured over a 3-year period in eight eastern Boreal Shield lakes: four lakes were studied before, 1 and 2 years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. ANOVAs showed a significant increase in total phosphorus (TP) in perturbed lakes when the three sampling dates were considered and in DOC concentrations when considering 1 year before and 1 year after the perturbation only. At 1 year post-clear cutting DOC concentrations were about 15 % greater in the perturbed lakes at ~ 15 mgC L−1 compared to 12.5 mgC L−1 in the unperturbed lakes. In contrast, absorbance and fluorescence measurements showed that all metrics remained within narrow ranges compared to the range observed in natural waters, indicating that forest harvesting did not affect the nature of DOM characterized with spectroscopic techniques. These results confirm an impact of forestry activities 1 year after the perturbation. However, this effect seems to be mitigated 2 years after, indicating that the system shows high resilience and may be able to return to its original condition in terms of water quality parameters assessed in this study.


2014 ◽  
Vol 13 (7) ◽  
pp. vzj2013.08.0155 ◽  
Author(s):  
Oili Kiikkilä ◽  
Aino Smolander ◽  
Liisa Ukonmaanaho

2016 ◽  
Vol 18 (10) ◽  
pp. 1316-1324 ◽  
Author(s):  
Yulin Jiang ◽  
Jianfu Zhao ◽  
Penghui Li ◽  
Qinghui Huang

This study investigated the multiple processes at the coastal plume zone by water quality characteristics and dissolved organic matter optical properties.


2007 ◽  
Vol 7 (2) ◽  
pp. 205-212
Author(s):  
Z.Y. Zhao ◽  
J.D. Gu ◽  
H.B. Li

Source water samples were collected from Guangzhou segment of Pearl River and filtered through Amicon® YC-05, YM-1, YM-3, YM-10, YM-30, YM-100 and ZM-500 membranes sequentially after pre-treatment. The apparent molecular weights of the 8 fractions were calibrated using high-performance size exclusion chromatograph (HPSEC) and they ranged from 0.36 to 182.6 kDa. These fractionated isolates and the raw water were disinfected by chlorine or chlorine dioxide to determine their disinfection characteristics. Results showed that apparent molecular weight of the main dissolved organic matter (DOM) in the RO isolate of water sample was less than 360 Da and this part of the DOM was mainly from anthropogenic activities and contamination of wastewater. RO fraction was the controlling factor for the raw water disinfection process according to the THMs concentrations detected. Disinfection by chlorine dioxide produced less THMs that by chlorine.


2021 ◽  
Author(s):  
Yuying Guan ◽  
Ruiming Han ◽  
Nannan Jia ◽  
Da Huo ◽  
Gongliang Yu

Abstract Dissolved organic matter (DOM) acts as a chemical intermediary between terrestrial and lacustrine ecosystems and significantly affects the structure and function of lakes. The optical characteristics of DOM have been widely used to estimate the water quality. However, little is known about its absorption and fluorescence under different trophic states. Especially, comparative research is needed among gradient eutrophic level of plateau lakes when considering their special characteristics. A total of 119 water samples were collected in the Erhai watershed from November 2018 to July 2019 to investigate the optical properties of DOM depending on the trophic state using ultraviolet–visible spectroscopy and parallel factor analysis of the excitation–emission matrix. The water quality conditions in the Erhai watershed were classified using the trophic state index (TSI; 31 < TSI < 67). The DOM is largely autochthonous and includes tyrosine-like protein (C1), tryptophan-like protein (C2), and humic-like compounds (C3). Except for an apparent trend of decreasing slope ratio (SR) (p < 0.01), both absorption coefficient at 254 nm and fluorescence intensity increase with the rising trophic state (p < 0.01). In this study, new models (R2aCDOM(254) = 0.762; R2 Fn(355) = 0.705, p < 0.01) basing on significant correlations between the TSI and aCDOM(254) and Fn(355) were established to predict the trophic state. The results of this study demonstrate that the effects of nutrients and environmental factors (pH and water temperature) on DOM vary depending on the trophic state and that the pH plays the main role in DOM production. Our analyses highlight the importance of DOM in aquatic ecosystems and the correlation between TSI and the optical properties of DOM. Our research unmasks the strong linkage between optical parameters of DOM and freshwater quality by applying neural network prediction.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4344 ◽  
Author(s):  
Seyed Mohammad Sadeghi-Nassaj ◽  
Teresa S. Catalá ◽  
Pedro A. Álvarez ◽  
Isabel Reche

Background Mono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named “extractive” species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown. Methods During more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (−holothurian) only contained around 810 individuals of Anemonia sulcata, whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali. We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and –holothurians (−H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four –H tanks that contained only 80 individuals of A. sulcata. Results In the time-series, absorption coefficients at 325 nm (a325) and spectral slopes from 275 to 295 nm (S275−295) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m−1 and 16 µm−1, respectively) than in the effluent of the −holothurian tank (average: 0.69 m−1 and 34 µm−1, respectively), the former being similar to those found in the inlet waters (average: 0.32 m−1 and 22 µm−1, respectively). This reduction in the absorption of the dissolved organic matter appears to be mediated by the POM consumption by holothurians. The experiments confirmed the results observed in the time-series. The a325 and S275−295 values were significantly lower in the treatment with holothurians than in the treatment without holothurians indicating a reduction in the concentration of chromophoric organic compounds, particularly of low molecular weight. Discussion Consequently, sea cucumbers appear to improve water transparency in aquaculture tanks. The underlying mechanism of this improvement might be related to the POM consumption by holothurians, which reduces the concentration of CDOM derived from POM disaggregation or to the direct assimilation of dissolved compounds of low molecular weight as chromophoric amino acids.


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