Organic Matter In Coastal Waters Research Articles

Mapping the Distribution of Organic Matter in Coastal Areas of Banyuwangi Regency

The Banyuwangi Regency Coastal Area is experiencing an increase in shrimp aquaculture and industrial business activities, which have the potential to cause environmental impacts. It is important to map the distribution of organic matter in coastal waters to address this problem. The main objective of this research is to map the distribution of organic matter in the waters of Banyuwangi Regency. The research method used is a descriptive. The study employed surveys and direct observation as data collection methods, and spatial analysis as the data analysis method. The results showed the mapping of the distribution of organic matter on the coast of Banyuwangi Regency, with the findings of the organic matter content on the Banyuwangi Coast with the lowest value ranging from 2,528 mg/L-9.00 mg/L located in the BL 2, KB 3, BL 3, and BWI 2 areas. The medium distribution value with a value range of 10.724 mg/L-39.18 mg/L is found in the BWI 1, WS 2, WS 1, WS 3, BWI 1, KB 2, KB 1, MC 2 areas. And the highest organic matter distribution value with a value range of 44.24-53.088 mg/L in the KL 2, KL 1, KL 3, BL 1, MC 1 and MC 3 areas. From the distribution results, a mapping picture of the organic matter content in the Banyuwangi Regency Coast is produced.

Use of Geospatial, Hydrologic, and Geochemical Modeling to Determine the Influence of Wetland-Derived Organic Matter in Coastal Waters in Response to Extreme Weather Events

Flooding from extreme weather events (EWE), such as hurricanes, exports large amounts of dissolved organic matter (DOM) to both estuaries and coastal waters globally. Hydrologic connectivity of wetlands to adjacent river channels during flood events is potentially a major control on the DOM exported to coastal waters after EWEs. In this study, a geographic information system based flood model was used to: 1) determine the volume of flooded wetlands in a river corridor following Hurricane Matthew in 2016; 2) compute the resulting volume fluxes of DOM to the Neuse River Estuary-Pamlico Sound (NRE-PS), in eastern North Carolina and 3) use the flood model to quantify the wetland contribution to DOM export. The flood model-derived contributions were validated with a Bayesian Monte Carlo mixing model combining measurements of DOM quality: specific UV Absorbance at 254 nm (SUVA254), spectral slope ratio (SR), and stable isotope ratios of dissolved organic carbon (13C-DOC). Results indicated that 1) hydrologic connectivity of the freshwater riparian wetlands caused the wetlands to become the primary source of organic matter (OM) that was exported into the NRE-PS after Matthew and 2) this source lingered in these coastal waters in the months after the storm. Thus, in consideration of the pulse-shunt concept, EWE such as Hurricane Matthew cause pulses of DOM from wetlands, which were the primary source of the OM shunted from the terrestrial environment to the estuary and sound. Wetlands constituted ca. 48% of the annual loading of DOC into the NRE and 16% of DOC loading into the PS. Results were consistent with prior studies in this system, and other coastal ecosystems, that attributed a high reactivity of DOM as the underlying reason for large CO2 releases following EWE. Adapting pulse-shunt concept to estuaries requires the addition of a “processing” step to account for the DOM to CO2 dynamics, thus a new pulse-shunt process is proposed to incorporate coastal waters. Our results suggest that with increasing frequency and intensity of EWE, strengthening of the lateral transfer of DOM from land to ocean will occur and has the potential to greatly impact coastal carbon cycling.

Use of Geospatial, Hydrologic, and Geochemical Modeling to Determine the Influence of Wetland-Derived Organic Matter in Coastal Waters in Response to Extreme Weather Events

Use of Geospatial, Hydrologic, and Geochemical Modeling to Determine the Influence of Wetland-Derived Organic Matter in Coastal Waters in Response to Extreme Weather Events

Tracing Different Freshwater Sources for Nutrients and Dissolved Organic Matter in Coastal Waters off Jeju Island Using Radon

In order to determine the origins of dissolved inorganic nutrients and dissolved organic matter in coastal waters off Jeju Island, Korea, we measured the concentrations of 222Rn, nutrients, fluorescent dissolved organic matter (FDOM), and dissolved organic carbon in coastal waters during September 2016 and October 2017. The lower salinity waters occurring in the southern coastal waters off Jeju (SCW) were characterized by higher nutrients and humic-like FDOM, while those in the western coastal waters off Jeju (WCW) showed no trend. A significant negative correlation between salinity and 222Rn in the SCW (r2 = 0.62, n = 7 for 2016; r2 = 0.56, n = 14 for 2017) indicates that freshwaters occurring in the SCW originate from fresh groundwater. However, depleted 222Rn activities in the fresh surface waters of the WCW indicate that those in the WCW originate mainly from the remote Changjiang diluted water. In general, the coastal ecosystem in the SCW is characterized by the dominance of brown seaweeds, and the WCW is by scleractinian corals. Our results imply that high nutrient concentrations in the SCW provide favorable conditions for the growth of seaweeds, while relatively low nutrient concentrations and high FDOM concentrations in the WCW provide favorable conditions for survival of corals.

Temporal and Spatial Distribution Characteristics of Colored Dissolved Organic Matter in Coastal Waters of Jiangsu Province

Temporal and Spatial Distribution Characteristics of Colored Dissolved Organic Matter in Coastal Waters of Jiangsu Province

Aggregation of organic matter in coastal waters: A dilemma of using a Couette flocculator

Aggregation of organic matter (OM) plays an important role in regulating the efficiency of biological pump. We investigated the effect of OM aggregation on bulk and compound-specific composition of particulate and dissolved samples from the coast of Avery Point, Connecticut, USA. Samples were incubated in a Couette device for 6h in the dark at 8rpm, which generated a mean shear of 3.4s−1. The shear induced a net aggregation (1.69µM-C, equivalent to 7.2% of initial particulate organic carbon; POC) and an even larger gross aggregation (7.43µM-C, equivalent to 31.5% of initial POC) in 6h. However, in a blank test, we found that Couette devices released a significant amount of uncharacterized dissolved organic matter (DOM) within 6h of the experiment. Blank tests have not been part of previous studies, but released DOM has to be taken into account when evaluating experimental data employing Couette devices. The relative abundance (as % of organic C and N) of labile POC components (i.e. amino acids and neutral aldoses in this study) decreased significantly in the treatment. There was no compound-specific selective degradation of amino acids or neutral aldoses in the particulate phase. The decrease of labile organic components and the increase of uncharacterized OM in the particulate phase, indicating that aggregation processes accumulate uncharacterized OM and lead to a more refractory POC. Further, our data indicate that aggregation processes may accumulate the element not essential for microbial growth under the specific environmental conditions. In this study, we found particulate C accumulates when microbial growth is N-limited.

Bacterial influence on chromophoric dissolved organic matter in coastal waters of the northern South China Sea

Bacterial influence on chromophoric dissolved organic matter in coastal waters of the northern South China Sea

Corrigendum to “Photochemical production of formaldehyde, acetaldehyde and acetone from chromophoric dissolved organic matter in coastal waters” [J. Photochem. Photobiol. A Chem. 226 (1) (2011) 16–22

Corrigendum to “Photochemical production of formaldehyde, acetaldehyde and acetone from chromophoric dissolved organic matter in coastal waters” [J. Photochem. Photobiol. A Chem. 226 (1) (2011) 16–22

Differentiating the role of different-sized microorganisms in peptide decomposition during incubations using size-fractioned coastal seawater

Peptide decomposition by different-sized microorganisms was compared by incubating tetrapeptide alanine–valine–phenylalanine–alanine (AVFA), a fragment of RuBisCO, in coastal seawater after size-fraction by filtration. The size-fractioned seawater included <0.8-μm filtered (free-living bacteria), <5-μm filtered (free-living bacteria+heterotrophic nanoflagellates), <20-μm filtered (free-living and particle-attached bacteria+heterotrophic nanoflagellates+other small protists), and unfiltered whole water collected from Texas coast in the western Gulf of Mexico. Decomposition rates of AVFA in the <20-μm and unfiltered seawater were significantly higher than those in the <0.8-μm and <5-μm seawater in the December 2011 incubation. The higher decomposition rate in the large size fractions can be attributed to activities of particle-attached bacteria and/or large-size microorganisms, such as osmotrophic protists. However, the role of particle-attached bacteria in explaining this decomposition difference might be limited, as bacterial abundance and community structure did not differ much among the 4 treatments. Consistently, the June 2013 incubation indicated that AVFA decomposed most rapidly in the unfiltered seawater with >20-μm microorganisms. This study provides insights into the relative role of different-sized microorganisms in regulating the recycling of labile organic matter in coastal waters.

Assessment of the colored dissolved organic matter in coastal waters from ocean color remote sensing.

Knowledge on absorption by colored dissolved organic matter, a(cdom), spatio-temporal variability in coastal areas is of fundamental importance in many field of researches related to biogeochemical cycles studies, coastal areas management, as well as land and water interactions in the coastal domain. A new method, based on the theoretical link between the vertical attenuation coefficient, K(d), and the absorption coefficient, has been developed to assess a(cdom). This method, confirmed from radiative transfer simulations and in situ measurements, and tested on an independent in situ data set (N = 126), allows a(cdom) to be assessed with a Mean Relative Absolute Difference, MRAD, of 33% over two order of magnitude (from 0.01 to 1.16 m(-1)). In the frame of ocean color observation, K(d) is not directly measured but estimated from the remote sensing reflectance, R(rs). Based on 109 satellite (SeaWiFS) and in situ coincident (i.e. match-up) data points a(cdom) is retrieved with a MRAD value of 37%. This simple model generally presents slightly better performances than recently developed empirical or semi-analytical algorithms.

Influence of microorganism content in suspended particles on the particle–water partitioning of mercury in semi-enclosed coastal waters

It is known that particle scavenging of mercury (Hg) can be affected by the abundance of particulate organic matter in coastal waters. However, the role of living organic particles in Hg scavenging is not yet completely understood. In this study, we hypothesized that an abundance of living organic particles (i.e., phytoplankton and bacteria) would influence the particle–water partitioning of Hg in coastal waters. Surface seawater samples were collected from eight stations in Gwangyang Bay, Korea, in three seasons (November 2009, April 2010, and October 2010) for the determination of concentrations of suspended particulate matter (including chlorophyll-a and bacteria), and Hg in unfiltered and filtered waters. We found that more Hg partitioned toward particulate matter when phytoplankton biomass, indicated from the chlorophyll-a concentration in a particle, was higher. In the low algal season, when [chlorophyll-a]<0.6μgL−1, the bacterial number, instead of chlorophyll-a concentration in particle, showed a positive correlation with the particle–water partition coefficient of Hg. Overall, microbial abundance seems to play a critical role in particle scavenging of Hg in coastal water. Taking this result in light of Hg in pristine coastal zones, we predict that increases in algal biomass amplify the potential for algae to transfer Hg to marine food chains.

Photochemical production of formaldehyde, acetaldehyde and acetone from chromophoric dissolved organic matter in coastal waters

Abstract Low molecular weight carbonyl compounds are produced photochemically from chromophoric dissolved organic matter (CDOM) in natural waters. Photoproduction rates for formaldehyde, acetaldehyde and acetone were measured in the laboratory using a pre-column 2,4-dinitrophenylhydrazine derivitization HPLC method as a function of optical properties (absorption coefficient, spectral slope) and irradiation time. Rates decreased linearly with decreasing absorption coefficient at 350 nm ( a (350 nm)), a measure of CDOM levels, with substantial variability in low a (350 nm) beach waters. Apparent quantum yields ( Θ ) were unchanged for a (350 nm) = 2–16 m −1 , but increased rapidly (×5) for beach waters with low a (350 nm) values. Θ increased linearly with increasing spectral slope for beach waters, consistent with enhanced production efficiency with photobleaching of CDOM in coastal waters. Θ trends with oxygen and molecular reaction probes (hydroxyl radical scavengers and producers) suggested a combination of direct photolysis and singlet oxygen quenching as primary production mechanisms.

Increases in the longwave photobleaching of chromophoric dissolved organic matter in coastal waters

Salinity effects on the photobleaching of chromophoric dissolved organic matter (CDOM) due to coastal mixing were investigated through a comparative study of surrogate and surface-water CDOM. Suwannee River humic acid (SRHA) and ultrafiltered river dissolved organic matter (UDOM) added to mixtures of river and seawater permeates (,1 kDa) that varied in salinity from 0 to 33 to mimic coastal mixing. Surface-water CDOM was collected from the Chesapeake Bay in January, June, and September 2002. Shortwave CDOM absorption loss (e.g., 280 nm) did not change with salinity; however, longwave CDOM absorption loss (e.g., 440 nm) often decreased by 10% to 40% with salinity. Apparent quantum yields for average absorption loss from 280 to 550 nm (Qavg) increased with salinity for both surrogate and surface-water CDOM, providing evidence for an effect of salinity independent of light absorption among different samples. Further, hydrogen peroxide photoproduction from UDOM increased from 15 to 368 nmol L 21 h 21 with salinity, even though pH values were circumneutral. A kinetic model demonstrated that, at circumneutral pH and iron concentrations expected for the Chesapeake Bay, photo-Fenton chemistry could not explain the increase in hydrogen peroxide production quantum yields (Qhp) with salinity. Using Qavg for the SRHA and UDOM surrogates, a model of the change in surface-water CDOM photoreactivity in the Chesapeake Bay as a function of salinity suggested additional CDOM inputs for the lower Chesapeake Bay. Because estuarine mixing increases photobleaching of longwave CDOM absorption, the modeling of absorption coefficients above 400 nm may underestimate dissolved organic matter in coastal waters.

Colored dissolved organic matter in coastal waters influenced by the Atchafalaya River, USA: effects of an algal bloom

Colored dissolved organic matter (CDOM) optical properties were studied in the northern Gulf of Mexico coastal waters influenced by the Atchafalaya River in July 2005 during a period of low river discharge using both field and satellite ocean color data. Although a general conservative CDOM absorption-salinity relationship between the riverine and oceanic end members were observed, deviations in surface CDOM absorption from this relationship (CDOM loss) and average higher spectral slope S of the log-linearized absorption spectra in comparison to bottom waters suggested photodegradation of surface CDOM. Excess CDOM absorption in bottom waters at many stations were associated with low oxygen or hypoxic conditions suggesting a potential CDOM source due to remineralization of organic matter in the bottom waters. At a few stations anomalously high CDOM absorption could be linked to biological production associated with algal blooms. Absorption spectra of a surface sample at one such station deviated from standard exponential form in the 300-400m UV range probably due to the presence of photo-protective pigments. CDOM derived from the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) using a regional algorithm provided a synoptic view of surface CDOM variations and the extent of river influences into the northern Gulf of Mexico.

Kinetics of iron complexation by dissolved natural organic matter in coastal waters

In coastal waters, where conditions are variable and can change rapidly, the kinetics of iron complexation by NOM is a major factor affecting its speciation. In this study we have examined the kinetics of complexation of ferrous and ferric iron by terrigenous NOM in terms of formation rate constants and dissociation rate constants by employing competitive ligand methods with visible spectrophotometry for determination of the complexed iron. Rate constants for organic ferrous complex formation ranged from 500 to 7.5×10 4 M −1 s −1, and rate constants for complex dissociation ranged from 1×10 −6 to 3.6×10 −3 s −1. Formation rate constants for organic ferric complexes were comparable to those determined for strong iron binding ligands found in the open oceans, and from 2.1×10 5 to 9.6×10 7 M −1 s −1. Ferric complex dissociation data were fitted by a two ligand model, with rate constants for both ligand classes typically higher than those for the strong ligands in the open ocean. Rate constants varied from 2×10 −4 to 4×10 −3 s −1 for the ‘weak’ ligand class, and from 1.0×10 −6 to 1.3×10 −4 s −1 for the ‘strong’ class. All rate constants varied by several orders of magnitude between NOM samples of different origin, reflecting the highly variable composition of these substances. Calculated conditional stability constants for organic complexes with ferric species in seawater, Fe′, were generally similar to those measured in the open oceans. Conditional stability constants for the ferrous complexes were less than those for the ferric complexes by two to four orders of magnitude. There was a weak positive correlation between the conditional stability constants for ferrous and ferric complexes, suggesting that similar functional groups are involved in binding each of the two forms of iron. One of the samples of NOM had a conditional stability constant with Fe′ that was comparable with those for siderophores and similar strong iron binding compounds. These results suggest that in the absence of oxidants, complexes between ferrous iron and NOM may be relatively long-lived. Our work also suggests that organic complexes between iron and terrigenous NOM may be quite strong, and will have a major effect on iron solubility in coastal waters.

Variations in the light absorption coefficients of phytoplankton, nonalgal particles, and dissolved organic matter in coastal waters around Europe

We measured the absorption properties of phytoplankton, nonalgal particles (NAP), and colored dissolved organic matter (CDOM) at about 350 stations in various coastal waters around Europe including the English Channel, Adriatic Sea, Baltic Sea, Mediterranean Sea, and North Sea. For comparison, we also collected data in the open ocean waters of North Atlantic. The exponential slope of the CDOM absorption spectrum varied within a narrow range around 0.0176 nm−1 (SD = 0.0020 nm−1). When data from all the regions were considered altogether, the relationship between phytoplankton absorption and chlorophyll concentration was generally similar to the one previously established for open oceanic waters. Our coastal data, however, show that significant departures from the general trend may occur due to peculiar pigment composition and cell size. In some coastal areas, high phaeopigment concentrations gave rise to especially high blue‐to‐red ratio of phytoplankton absorption. The NAP absorption covaried with the particle dry weight. Most absorption spectra of these particles were well described by an exponential function with a slope averaging 0.0123 nm−1 (SD = 0.0013 nm−1). In some highly turbid waters, the spectra exhibited a signature possibly associated with iron oxides. In the Baltic Sea, NAP absorption systematically showed lower values at wavelengths shorter than 440 nm than predicted from the fitted exponential function. Overall, the variability in the absorption properties of European coastal waters showed some consistent patterns despite the high diversity of the examined waters. Distinct features were identified in the phytoplankton and NAP components. An absorption budget is presented and parameterizations are proposed.

Sources and diagenetic alteration of organic matter in coastal waters at the vicinity of Dar es Salaam, Tanzania.

The stable isotope compositions of organic carbon (OC) and nitrogen, contents of OC and nitrogen, and C/N ratios for four short cores, which were recovered from Msansani Bay (WO 57), off Msimbazi River (WO 76) and Dar es Salaam harbour (WO 62 and WO 74), are used to document temporal variation in the sources and diagenetic alteration of organic matter (OM). The δ15N and δ13C values at sites WO 57, WO 62 and WO 74 show a trend of down-core decrease to the base of the core, and such a down-core trend could be related to diagenetic loss of compounds enriched in 13C and 15N. At site WO 76, the δ13C values show two zones that are depleted in 13C. These two zones correspond to black-greasy layers that were observed during sampling, and low δ13C values probably is an indication that the material was derived from the continent. Furthermore, these two zones have elevated values of OC, nitrogen and C/N ratios. The stable isotopes of OC and nitrogen show inter-sites differences with enrichment in 15N in the following order: WO 57 Tanzania Journal of Science Volume 27A (Special Issue) 2001, pp. 39-55

Molecular characterization of microgram amounts of oceanic colloidal organic matter by direct temperature-resolved ammonia chemical ionization mass spectrometry

Marine colloidal organic matter in coastal waters off the coast of the eastern United States (from Georges Bank and the Mid-Atlantic Bight) is characterized by means of direct temperature-resolved mass spectrometry (DT-MS). Chemical ionization (NH 3) appears to be a very appropriate ionization method for this material. The analytical data confirm the presence of a significant polysaccharide fraction consisting of neutral sugars (normal-, deoxy- and methylated aldoses), N-acetyl aminosugars and, possibly, acidic sugars. The methylated and N-acetyl aminosugars are considered as markers for a bacterial contribution. No evidence is found for polysaccharides with large homopolymeric domains, suggesting an origin distinct from the common structural polysaccharides that comprise major polymers in algae and higher plants. The TIC profiles, which express the number of ions produced as a function of the temperature, often show a bimodal distribution. This indicates that the colloidal matter consists of two fractions with different thermal stabilities and probably also different chemical stabilities. Multivariate “mapping” of the DT-MS spectra reveals that the chemical differences between these two fractions show remarkable conformity amongst samples collected at widespread locations. The relative abundance of the two fractions appears to depend on both depth and location. The more thermally stable fraction is relatively abundant in deep water samples and some surface waters of the Mid-Atlantic Bight.

C18 Sep-Pak extractable trace metals in waters from the Gulf of Lions

Abstract Dissolved trace-metal (Cd, Cu, Fe, Ni and Pb) interactions with C18 Sep-Pak extractable organic matter have been investigated in the Rhone mouth and in the Gulf of Lions in July 1989. Pb and Cd do not show any complexation while Ni and Fe are slightly complexed in surface waters near the Rhone mouth. Up to 40% of total dissolved Cu is complexed by the extractable organic matter in coastal waters and, in open sea waters a subsurface maximum of 64% of complexed Cu was observed, apparently linked to the maximum of primary production. Our results combined with other data on the same area suggest that in the euphotic zone of the western Mediterranean Sea, organic matter directly connected to primary production and associated degradation processes is contributing to this complexation as well as to the enrichment of colloidal fraction and the increase of the discrepancy between concentrations of dissolved organic carbon according to the method of Sugimura and Suzuki (1988) and by traditional techniques.

Parameters of productivity and metabolism of coral reef ecosystems off central Vietnam

Primary production of phytoplankton in coastal waters off central Vietnam (20–100 mg C m −2 day −1) was depleted over the shallow coral reefs (1–5 mg C m −3 day −1). Planktonic bacteria totalled 0·2–2 × 10 6 cells ml −1, wet biomass was 50–1250 mg m −3, and productivity was 50–200 mg m −3 day −1 of wet biomass (or 10–40 mg C m −3 day −1). The biomass of planktonic protozoa (ciliates and zooflagellates) in waters off the reefs was 100–300 mg m −3 with depletion by grazing over the reefs being 1–5 mg m −3. Total respiration rates of microplankton were within the range 0·2–1 mg O 2l −1 day −1, respiration of bacteria comprising 80–90% of the total. The stock of labile (potentially utilizable by planktonic microflora) organic matter in coastal waters varied from 0·3 to 3 mg C l −1, higher values corresponding with waters over the active coral reef. The excretion of organic matter by corals as well as the respiration and photosynthesis rates in different components of bottom biotopes were measured. The roles of bacteria, algae and planktonic protozoa in coral reef trophodynamics are discussed.