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Oliveira, Eduardo Negri de, Bastiaan Adriaan Knoppers, João Antônio Lorenzzetti, Paulo Ricardo Petter Medeiros, Maria Eulália Carneiro, and Weber Friederichs Landim de Souza. "A satellite view of riverine turbidity plumes on the NE-E Brazilian coastal zone." Brazilian Journal of Oceanography 60, no. 3 (September 2012): 283–98. http://dx.doi.org/10.1590/s1679-87592012000300002.
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Turbidity plumes of São Francisco, Caravelas, Doce, and Paraiba do Sul river systems, located along the NE/E Brazilian coast, are analyzed for their dispersal patterns of Total Suspended Solids (TSS) concentration using Landsat images and a logarithmic algorithm proposed by Tassan (1987) to convert satellite reflectance values to TSS. The TSS results obtained were compared to in situ collected TSS data. The analysis of the satellite image data set revealed that each river system exhibits a distinct turbidity plume dispersal pattern. The behavior, dimension and degree of turbidity of the São Francisco River plume have been greatly altered by the construction of a cascade of hydroelectric dam reservoirs in its hydrological basin. The plume has lost its typical unimodal seasonal pattern of material dispersion and its turbidity has decreased due to the regulation of river flow by the dams and TSS retainance by the reservoirs. In contrast, the Doce and Paraíba do Sul river plumes are still subject to seasonal pulsations and show more turbid conditions than the SF plume, as dams are less numerous, set in the middle river sections and the natural river flow has been maintained. The Caravelas Coastal System river plume is restricted to near shore shallow waters dominated by resuspension processes. During austral spring and summer when NE-E winds prevail, all plumes generally disperse southward. Short-term northward reversals may occur in winter with the passage of atmospheric cold fronts. The São Francisco and Doce river plumes tend to disperse obliquely to the coast and transport materials further offshore, while the Caravelas and Paraíba do Sul plumes tend to disperse mainly parallel to the coast, enhancing TSS retention nearshore.
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Grimes, CB, and MJ Kingsford. "How do Riverine Plumes of Different Sizes Influence Fish Larvae: do they Enhance Recruitment?" Marine and Freshwater Research 47, no. 2 (1996): 191. http://dx.doi.org/10.1071/mf9960191.
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A review of the literature suggests that river discharge plumes strongly influence fish larvae and may play a significant role in the recruitment of local fishes. Some rivers drain large land masses to discharge shallow, turbid and nutrient-rich plumes that interact with ocean currents as well as with local oceanography and meteorology; these plumes may extend hundreds of kilometres offshore and alongshore. The frontal, or mixing, zone between plume and ocean waters is characterized by strong physical and biological processes. Physical dynamics, e.g. hydrodynamic convergence, and abundant nutrients (both river derived and upwelled) in the vicinity of discharge plumes often generate large stocks of phytoplankton, zooplankton and fish larvae, as well as high rates of primary and secondary production. Physical dynamics not only act to accumulate (and probably retain) biomass in frontal waters, but also transport organisms onshore, offshore and along the frontal boundary. The mechanisms through which river plumes may influence recruitment are not clear. In considering the potential effects of scale of river discharge on recruitment, three alternative hypotheses are discussed. The short-food-chain hypothesis states that recruitment will be enhanced in the vicinity of river plumes because fish larvae experience superior feeding conditions, grow faster and thus experience a shorter stage duration and survive better. The total-larval-production hypothesis is that trophic conditions support such high total production of fish larvae that specific dynamics of growth and mortality are not relevant. The third hypothesis is that plumes facilitate the retention of fish larvae within a limited area, and it is the physical retention rather than production that explains the variation in recruitment. If one or a combination of these hypotheses explains the influence of river plumes on recruitment, then the greatest potential to affect fish recruitment may be possessed by large mid-latitude rivers carrying high suspended-sediment and nutrient loads that discharge into shelf waters to create well defined plumes where primary and secondary production are high.
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Devlin, Michelle, and Britta Schaffelke. "Spatial extent of riverine flood plumes and exposure of marine ecosystems in the Tully coastal region, Great Barrier Reef." Marine and Freshwater Research 60, no. 11 (2009): 1109. http://dx.doi.org/10.1071/mf08343.
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Tully River flood plume monitoring data for 11 events (1994–2008) were used to determine what physical characteristics of the floods (size of flood, direction of plume movement, shape of hydrograph) most influence the flood plume water quality and areal extent. During some events, the maximum area influenced by the Tully flood plumes extended into the Coral Sea. Areal extents depended on wind direction and discharge volume, with large extents more likely during light or northerly winds. Strong gradients in water quality existed away from the Tully mouth during the wet season and the adjacent marine ecosystems were regularly exposed to land-derived material. Flood plumes were grouped into three plume types: primary, secondary and tertiary plumes, based on water-quality characteristics (suspended solids, coloured dissolved organic matter and chlorophyll). The number of reefs and seagrasses exposed to plume waters varied from year to year, and was dependent on the characteristics of the event. Over the 11 years, out of the major 37 reefs and 13 seagrass meadows identified in the Tully marine area, between 11 (30%) and 37 coral reefs (100%) and most of the seagrass meadows were inundated by either a primary or secondary plume every year.
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Marta-Almeida, Martinho, Anna Dalbosco, David Franco, and Manuel Ruiz-Villarreal. "Dynamics of river plumes in the South Brazilian Bight and South Brazil." Ocean Dynamics 71, no. 1 (November 11, 2020): 59–80. http://dx.doi.org/10.1007/s10236-020-01397-x.
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AbstractThe plumes from the rivers of the South Brazilian Bight (SBB) and South Brazil (SB) were studied using a realistic model configuration. River plume variability on continental shelves is driven by the input of river runoff into the shelf, by wind variability, and also by ambient currents and its seasonal variability, especially the Brazil Current, which are realistically modelled in this study. It is presented a simulation of 4 years using a nested configuration, which allows resolving the region around Florianópolis with very high resolution (∼150 m). The dispersion of river plumes was assessed not only with the hydrodynamical model results but also by using passive tracers whose dynamics was analyzed seasonally. Several dyes were released together with the river discharges. This approach allowed calculating the depths of the riverine freshwater, and the resulting regions affected by the plumes. Northward intrusions of waters from the southern region, under the potential influence of the distant La Plata river plume, were evaluated with a Lagrangian approach. The local river plumes are confined to the inner shelf, except south of 30°S where discharges from Lagoa dos Patos disperse over the shelf in the spring and summer. The Brazil Current flowing southward over the slope prevents the river plumes from interaction with oceanic mesoscale dynamics. The river plumes are, thus, mainly controlled by the wind forcing. The plumes from SBB are able to disperse until SB following the southward wind regime typical of the summer. And both the SB and La Plata river plumes are also able to reach SBB, forced by the northward wind typical of the winter season, until the latitude of 25.5°S. A low salinity belt (below 35) is present along the coastal region of SB and SBB year-round, supported by contributions from both the large and small rivers. The interaction between the different plumes influences the dispersion patterns, shielding the Florianṕolis coastal region from plumes of distant rivers, and dispersing the plume of SBB rivers away from Santa Catarina Island as it disperses southward during the summer months.
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Carter, B. R., J. R. Toggweiler, R. M. Key, and J. L. Sarmiento. "Processes determining the marine alkalinity and carbonate saturation distributions." Biogeosciences Discussions 11, no. 7 (July 21, 2014): 11139–78. http://dx.doi.org/10.5194/bgd-11-11139-2014.
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Abstract. We introduce a composite tracer, Alk*, that has a global distribution primarily determined by CaCO3 precipitation and dissolution. Alk* also highlights riverine alkalinity plumes that are due to dissolved calcium carbonate from land. We estimate the Arctic receives approximately twice the riverine alkalinity per unit area as the Atlantic, and 8 times that of the other oceans. Riverine inputs broadly elevate Alk* in the Arctic surface and particularly near river mouths. Strong net carbonate precipitation lowers basin mean Indian and Atlantic Alk*, while upwelling of dissolved CaCO3 rich deep waters elevates Northern Pacific and Southern Ocean Alk*. We use the Alk* distribution to estimate the carbonate saturation variability resulting from CaCO3 cycling and other processes. We show regional variations in surface carbonate saturation are due to temperature changes driving CO2 fluxes and, to a lesser extent, freshwater cycling. Calcium carbonate cycling plays a tertiary role. Monitoring the Alk* distribution would allow us to isolate the impact of acidification on biological calcification and remineralization.
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Martins, Meike Sena, and Detlef Stammer. "Interannual Variability of the Congo River Plume-Induced Sea Surface Salinity." Remote Sensing 14, no. 4 (February 19, 2022): 1013. http://dx.doi.org/10.3390/rs14041013.
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Based on satellite surface salinity (SSS) observations from the SMOS, Aquarius and SMAP missions, we investigate the interannual SSS variability during the period from 2010 to 2020 in the Gulf of Guinea, impacted by the Congo River run-off. Combined with in situ data, the available 11 years of satellite salinity data suggest that the plume of Congo run-off primarily spreads into western directions, leading to reduced SSS. A fraction of it also shows a coastal southward extent subject to interannual variability influenced by coastal trapped waves. The low-salinity water is associated with high values of net primary production, confirming the riverine origin of the nutrient rich plume. No correlation can be found between the plume patterns and the different upwelling strengths in the subsequent upwelling months, nor could a correlation be found with the occurrence of the Benguela Niños. Linking the occurrence of a barrier layer to the occurrence of low-salinity plumes remains difficult, mainly because of the sparseness of in situ data. However, the influence of the low-salinity layer is evident in its stronger stratification and an increased available potential energy.
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Gancheva, Irina, Elisaveta Peneva, and Violeta Slabakova. "Detecting the Surface Signature of Riverine and Effluent Plumes along the Bulgarian Black Sea Coast Using Satellite Data." Remote Sensing 13, no. 20 (October 13, 2021): 4094. http://dx.doi.org/10.3390/rs13204094.
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The clear and reliable detection of effluent plumes using satellite data is especially challenging. The surface signature of such events is of a small scale; it shows a complex interaction with the local environment and depends greatly on the effluent and marine water constitution. In the context of remote sensing techniques for detecting treated wastewater discharges, we study the surface signature of small river plumes, as they share specific characteristics, such as higher turbidity levels and increased nutrient concentration, and are fresh compared to the salty marine water. The Bulgarian Black Sea zone proves to be a challenging study area, with its optically complex waters and positive freshwater balance. Additionally, the Bulgarian Black Sea coast is a known tourist destination with an increased seasonal load; thus, the problem of the identification of wastewater discharges is a topical issue. In this study, we analyze the absorption components of the Inherent Optical Properties (IOPs) for 84 study points that are located at outfall discharging areas, river estuaries and at different distances from the shoreline, reaching the open sea area at a bottom depth of more than 2000 m. The calculations of IOPs take into account all available Sentinel 2 cloudless acquisitions for three years from 2017 until 2019 and are performed using the Case-2 Regional CoastColour (C2RCC) processor, implemented in the Sentinel Application Platform (SNAP). The predominant absorber for each study area and its temporal variation is determined, deriving the specific characteristics of the different areas and tracking their seasonal and annual course. Optical data from the Galata AERONET-OC site are used for validating the absorption coefficient of phytoplankton pigment. A conclusion regarding the possibility of distinguishing riverine, marine and coastal water is derived. The study provides a sound basis for estimating the advantages and drawbacks of optical satellite data for tracking the extent of effluent and fluvial plumes with unknown concentrations of optically significant seawater constituents.
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Garzon-Garcia, Alexandra, Joanne M. Burton, Stephen Lewis, Zoe Bainbridge, Rob De Hayr, Philip Moody, and Jon Brodie. "The bioavailability of nitrogen associated with sediment in riverine plumes of the Great Barrier Reef." Marine Pollution Bulletin 173 (December 2021): 112910. http://dx.doi.org/10.1016/j.marpolbul.2021.112910.
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Kasurinen, V., H. Aarnos, and A. Vähätalo. "Biologically labile photoproducts from riverine non-labile dissolved organic carbon in the coastal waters." Biogeosciences Discussions 12, no. 11 (June 2, 2015): 8199–234. http://dx.doi.org/10.5194/bgd-12-8199-2015.
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Abstract. In order to assess the production of biologically labile photoproducts (BLPs) from non-labile riverine dissolved organic carbon (DOC), we collected water samples from ten major rivers, removed labile DOC and mixed the residual non-labile DOC with artificial seawater for microbial and photochemical experiments. Bacteria grew on non-labile DOC with a growth efficiency of 11.5% (mean; range from 3.6 to 15.3%). Simulated solar radiation transformed a part of non-labile DOC into BLPs, which stimulated bacterial respiration and production, but did not change bacterial growth efficiency (BGE) compared to the non-irradiated dark controls. In the irradiated water samples, the amount of BLPs stimulating bacterial production depended on the photochemical bleaching of chromophoric dissolved organic matter (CDOM). The apparent quantum yields for BLPs supporting bacterial production ranged from 9.5 to 76 (mean 39) (μmol C mol photons−1) at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320) (μmol C mol photons−1). According to the calculations based on spectral apparent quantum yields and local solar radiation, the annual production of BLPs ranged from 21 (St. Lawrence) to 584 (Yangtze) mmol C m−2 yr−1 in the plumes of the examined rivers. Complete photobleaching of riverine CDOM in the coastal ocean was estimated to produce 10.7 Mt C BLPs yr−1 from the rivers examined in this study and globally 38 Mt yr−1 (15% of riverine DOC flux from all rivers), which support 4.1 Mt yr−1 of bacterial production and 33.9 Mt yr−1 bacterial respiration.
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Buck, Kristen N., Maeve C. Lohan, Carolyn J. M. Berger, and Kenneth W. Bruland. "Dissolved iron speciation in two distinct river plumes and an estuary: Implications for riverine iron supply." Limnology and Oceanography 52, no. 2 (March 2007): 843–55. http://dx.doi.org/10.4319/lo.2007.52.2.0843.
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Koliyavu, Timoci, Chloe Martias, Awnesh Singh, Stéphane Mounier, Philippe Gérard, and Cecile Dupouy. "In-Situ Variability of DOM in Relation with Biogeochemical and Physical Parameters in December 2017 in Laucala Bay (Fiji Islands) after a Strong Rain Event." Journal of Marine Science and Engineering 9, no. 3 (February 24, 2021): 241. http://dx.doi.org/10.3390/jmse9030241.
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Heavy rain events alter the biogeochemical outflows, affects water quality and ecosystem health within the coastal waters of small Pacific Islands. We characterized snapshots of the optical fingerprints of dissolved organic matter (DOM) sources together with the select nutrients, biogeochemical and physical variables for 10 stations in December 2017 in Laucala Bay, Fiji Islands. DOM absorption coefficients and fluorescence components were determined via spectrofluorometry and Parallel Factor Analysis identifying four components: Type M, two terrestrial (humic, fulvic) components, and a protein component linked to marine biological activity. Associations of DOM together with climate variables and the other tested variables were determined via principal component, hierarchical cluster, and cross-correlation (Pearson) analysis. All component s (together with most tested variables) displayed higher values (plumes) at the southwest coast consistent with surface currents outflow during the wet season. Type M component associated with two allochthonous fluorescent components signaling anthropogenic forcings via riverine outflows. Terrigenous inputs association with autochthonous chromophoric dissolved organic matter (CDOM) is indicative of tidal mixing, dilution, and bottom resuspension processes. Positive correlations of dissolved organic carbon (DOC) with nutrients (NOx, PO4) elucidates DOM being utilized as energy sources. The positive correlation of DON with nutrients (NOx, PO4, Si(OH)4) reflects the role of DON as a nutrient source consistent with chlorophyll plume formation.
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Álvarez-Romero, Jorge G., Michelle Devlin, Eduardo Teixeira da Silva, Caroline Petus, Natalie C. Ban, Robert L. Pressey, Johnathan Kool, et al. "A novel approach to model exposure of coastal-marine ecosystems to riverine flood plumes based on remote sensing techniques." Journal of Environmental Management 119 (April 2013): 194–207. http://dx.doi.org/10.1016/j.jenvman.2013.01.036.
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Korotenko, Konstantin, Alexander Osadchiev, and Vasiliy Melnikov. "Mesoscale Eddies in the Black Sea and Their Impact on River Plumes: Numerical Modeling and Satellite Observations." Remote Sensing 14, no. 17 (August 24, 2022): 4149. http://dx.doi.org/10.3390/rs14174149.
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The Northeast Caucasian Current (NCC) is the northeastern part of the cyclonic Rim Current (RC) in the Black Sea. As it sometimes approaches the narrow shelf very closely, topographically generated cyclonic eddies (TGEs) can be triggered. These eddies contribute to intense, along- and cross-shelf transport of trapped water with enhanced self-cleaning effects of the coastal zone. Despite intense studies of eddy dynamics in the Black Sea, the mechanisms of the generation of such coastal eddies, their unpredictability, and their capacity to capture and transport impurities are still poorly understood. We applied a 3-D low-dissipation model DieCAST/Die2BS coupled with a Lagrangian particle transport model supported by analysis of optical satellite images to study generation and evolution of TGEs and their effect on river plumes unevenly distributed along the northeastern Caucasian coast. Using the Furrier and wavelet analyses of kinetic energy time series, it was revealed that the occurrence of mesoscale TGEs ranges from 10 up to 50 days. We focused on one particular isolated anticyclonic TGE that emerged in late fall as a result of instability of the RC impinging on the abrupt submarine area adjoining the Pitsunda and Iskuria capes. Being shed, the eddy with a 30-km radius traveled along the coast as a coherent structure during ~1.5 months at a velocity of ~3 km/day and vertical vorticity normalized by the Coriolis parameter ~(0.1 ÷ 1.2). This eddy captured water from river plumes localized along the coast and then ejected it to the open sea, providing an intense cross-shelf transport of riverine matter.
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Gaspar, Felipe Lima, Barbara Ramos Pinheiro, Carlos Esteban Delgado Noriega, Moacyr Araujo, Nathalie Lefèvre, and Manuel de Jesus Flores Montes. "Alkalinity, inorganic carbon and CO2 flux variability during extreme rainfall years (2010-2011) in two polluted tropical estuaries NE Brazil." Brazilian Journal of Oceanography 66, no. 1 (March 2018): 115–30. http://dx.doi.org/10.1590/s1679-87592018149406601.
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Abstract The susceptibility of coastal environments to shifts in the biogeochemical cycles of carbon and nutrients driven by anthropogenic pressure and climate change is a real challenge for the scientific community. This paper evaluated the effects of an extreme rainfall event over the nutrients and carbonate parameters in two polluted tropical estuaries. Surface water samples were taken seasonally along a salinity gradient in the Capibaribe and Barra de Jangadas estuaries in order to investigate the spatial and seasonal variability of dissolved nutrients, chlorophyll-a, dissolved oxygen, total alkalinity, inorganic carbon, partial pressure of CO2 (pCO2) and CO2 fluxes. The increased riverine influence caused by the fluvial flooding during the extremely rainy season augmented the nitrogen concentrations in the plumes, which also presented reduced salinity, alkalinity and dissolved oxygen values. In the Capibaribe plume it has also shifted the mean CO2 flux value of - 4.01 mmolC m-2 d-1 during the dry season, to a positive mean flux of + 5.7 mmolC m-2 d-1 during the rainy season. Within the estuaries the BOD5,20 and dissolved phosphorus values were higher during the dry season (p<0.0001), they showed positive correlation with the phytoplanktonic blooms that reached a chl-a value of 85 mg m-3 in the Capibaribe. The high alkalinity found in both estuaries, with mean values between dry and wet seasons respectively from 1808 to 1373 µmol kg-1 in the Capibaribe estuary and 1616 to 1058 µmol kg-1 in Barra de Jangadas estuary, may act as a buffer to the process of coastal acidification due to eutrophication. The increased rivers discharge lead to a greater transport of organic matter and nutrients to the coast, decreasing the oxygen availability and shifting the metabolic status of the estuarine plume to heterotrophic, whereas increased the water quality within the estuaries due the flushing promoted by the extreme rainfall event.
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Oubelkheir, Kadija, Phillip W. Ford, Nagur Cherukuru, Lesley A. Clementson, Caroline Petus, Michelle Devlin, Thomas Schroeder, and Andrew D. L. Steven. "Impact of a Tropical Cyclone on Terrestrial Inputs and Bio-Optical Properties in Princess Charlotte Bay (Great Barrier Reef Lagoon)." Remote Sensing 15, no. 3 (January 22, 2023): 652. http://dx.doi.org/10.3390/rs15030652.
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In January 2013, tropical cyclone Oswald caused widespread flooding in the North-East coast of Australia, and large and highly episodic inputs into Princess Charlotte Bay (PCB, northern Great Barrier Reef). Freshwater outflows from the Normanby and Kennedy rivers, the two main rivers draining the adjacent catchments, resulted in drastic changes in physical, biogeochemical and optical properties within PCB. On 31 January, 2 days after the peak riverine discharge from the Normanby river, nutrients and dissolved organic matter contents peaked under the influence of large outflows from the Kennedy river into the western section of the bay (5.8 mM for dissolved inorganic nitrogen, 6.9 g m−3 for dissolved organic carbon and 6.1 m−1 for the colored dissolved organic matter absorption coefficient at 412 nm). In the eastern section of the bay, the situation appeared more ‘mixed’, with a suspended solids concentration reaching 23.1 g m−3 close to the Normanby river mouth. The main phytoplankton bloom occurred in the transition zone between the Kennedy and Normanby flood plumes, and was dominated by diatoms with a chlorophyll a concentration reaching 14.6 mg m−3. This study highlights the need to better describe the critical spatial and temporal scales of variability of key biogeochemical and optical properties after a major flood event. The data collected is key to improve the accuracy of ocean color remote sensing algorithms and regional biogeochemical budgets following highly episodic inputs.
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Domingues, Ricardo, Matthieu Le Hénaff, George Halliwell, Jun A. Zhang, Francis Bringas, Patricia Chardon, Hyun-Sook Kim, Julio Morell, and Gustavo Goni. "Ocean Conditions and the Intensification of Three Major Atlantic Hurricanes in 2017." Monthly Weather Review 149, no. 5 (May 2021): 1265–86. http://dx.doi.org/10.1175/mwr-d-20-0100.1.
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AbstractMajor Atlantic hurricanes Irma, Jose, and Maria of 2017 reached their peak intensity in September while traveling over the tropical North Atlantic Ocean and Caribbean Sea, where both atmospheric and ocean conditions were favorable for intensification. In situ and satellite ocean observations revealed that conditions in these areas exhibited (i) sea surface temperatures above 28°C, (ii) upper-ocean heat content above 60 kJ cm−2, and (iii) the presence of low-salinity barrier layers associated with a larger-than-usual extension of the Amazon and Orinoco riverine plumes. Proof-of-concept coupled ocean–hurricane numerical model experiments demonstrated that the accurate representation of such ocean conditions led to an improvement in the simulated intensity of Hurricane Maria for the 3 days preceding landfall in Puerto Rico, when compared to an experiment without the assimilation of ocean observations. Without the assimilation of ocean observations, upper-ocean thermal conditions were generally colder than observations, resulting in reduced air–sea enthalpy fluxes—enthalpy fluxes are more realistically simulated when the upper-ocean temperature and salinity structure is better represented in the model. Our results further showed that different components of the ocean observing system provide valuable information in support of improved TC simulations, and that assimilation of underwater glider observations alone enabled the largest improvement over the 24 h time frame before landfall. Our results, therefore, indicated that ocean conditions were relevant for more realistically simulating Hurricane Maria’s intensity. However, further research based on a comprehensive set of hurricane cases is required to confirm robust improvements to forecast systems.
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Gancheva, Irina. "Analysis of hyperspectral and multispectral reflectance spectra in the Black Sea coastal area near the Danube delta: comparison of PRISMA and Sentinel-2 observations." Journal of Physics: Conference Series 2255, no. 1 (April 1, 2022): 012015. http://dx.doi.org/10.1088/1742-6596/2255/1/012015.
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Abstract In this study we investigate the possibility to distinguish between different water types in the Danube delta and the Black Sea coastal zone based on the reflectance spectra. For this we use hyperspectral satellite images from PRISMA (PRecursore IperSpettrale della Missione Applicativa) and multispectral images from Sentinel-2 MSI (MultiSpectral Instrument) in July 2020. The visual inspection of the available acquisitions differentiates between four aquatic types: lagoons; river and stream plumes mixing with marine waters; turbid and optically complex coastal waters; and optically clean waters away from the shore. For each of the four types we determine the characteristic averaged reflectance spectra from PRISMA and Sentinel-2 for the spectral range from 400 nm to 2500 nm. It is found that Sentinel-2 spectra are very similar for the 4 water types, in contrast to the PRISMA spectra which give substantial additional information. Further we analyse the gradual modification of the characteristic hyper- and multispectral spectra from the shoreline to the open sea (∼25 km distance) in 15 locations passing through areas of varying turbidity. We demonstrate that the intensity of surface reflectance from the hyperspectral instrument decreases gradually with distance from shoreline, clearly showing the transition zone between riverine and marine water. The multispectral reflectance spectra for the same study areas did not present such consistent behaviour. The presented results demonstrate the benefits of hyperspectral over multispectral images for turbid aquatic regions in the Black Sea coastal zone. They show that with little requirements regarding pre-processing and computational resources hyperspectral data can contribute greatly to classification of water types, in respect of their turbidity.
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da Silva, Douglas Vieira, Phelype Haron Oleinik, Juliana Costi, Eduardo de Paula Kirinus, Wiliam Correa Marques, and Osmar Olinto Moller. "Variability of the Spreading of the Patos Lagoon Plume Using Numerical Drifters." Coasts 2, no. 2 (April 6, 2022): 51–69. http://dx.doi.org/10.3390/coasts2020004.
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The Patos Lagoon coastal plume is a small-scale outflow that is strongly controlled by meteorological tides. However, the riverine discharge of the lagoon is subject to high decadal variability. Hence, the discharge amount alters the scale of this coastal plume and its effects over the inner shelf environment. This study uses hydrodynamic simulations and a Lagrangian model to estimate the spreading of the plume under two different discharge conditions.Through scale parameters, we characterized the contrasts of the plume structure between high discharge and low discharge conditions. During a strong discharge regime, the width and thickness of the plume are enhanced, and the inertial processes increase against the frictional effect of the wind. The consequences of these differences include higher values of alongshore and cross-shore spreading of the drifters for the strong discharge regime. These findings indicate that under similar wind conditions, different amounts of riverine discharges alter the extent to which the material delivered by the plume can spread over the inner continental shelf.
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Jayasinghe, Amadini, Scott Elliott, Anastasia Piliouras, Jaclyn Clement Kinney, Georgina Gibson, Nicole Jeffery, Forrest Hoffman, Jitendra Kumar, and Oliver Wingenter. "Modeling Functional Organic Chemistry in Arctic Rivers: An Idealized Siberian System." Atmosphere 11, no. 10 (October 13, 2020): 1090. http://dx.doi.org/10.3390/atmos11101090.
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Rivers of the Arctic will become ever more important for the global climate, since they carry a majority of continental dissolved organic carbon flux into the rapidly changing polar ocean. Aqueous organics comprise a wide array of functional groups, several of which are likely to impact coastal and open water biophysical properties. Light attenuation, interfacial films, aerosol formation, gas release and momentum exchange can all be cited. We performed Lagrangian kinetic modeling for the evolution of riverine organic chemistry as the molecules in question make their way from the highlands to Arctic outlets. Classes as diverse as the proteins, sugars, lipids, re-condensates, humics, bio-tracers and small volatiles are all included. Our reduced framework constitutes an idealized northward flow driving a major hydrological discharge rate and primarily representing the Russian Lena. Mountainous, high solute and tundra sources are all simulated, and they meet up at several points between soil and delta process reactors. Turnover rates are parameterized beginning with extrapolated coastal values imposed along a limited tributary network, with connections between different terrestrial sub-ecologies. Temporal variation of our total dissolved matter most closely resembles the observations when we focus on the restricted removal and low initial carbon loads, suggesting relatively slow transformation along the water course. Thus, channel combinations and mixing must play a dominant role. Nevertheless, microbial and photochemical losses help determine the final concentrations for most species. Chemical evolution is distinct for the various functionalities, with special contributions from pre- and post-reactivity in soil and delta waters. Several functions are combined linearly to represent the collective chromophoric dissolved matter, characterized here by its absorption. Tributaries carry the signature of lignin phenols to segregate tundra versus taiga sources, and special attention is paid to the early then marine behaviors of low molecular weight volatiles. Heteropolycondensates comprise the largest percentage of reactive carbon in our simulations due to recombination/accumulation, and they tend to be preeminent at the mouth. Outlet concentrations of individual structures such as amino acids and absorbers lie above threshold values for biophysical influence, on the monolayer and light attenuation. The extent of coastal spreading is examined through targeted regional box modeling, relying on salinity and color for calibration. In some cases, plumes reach the scale of peripheral arctic seas, and amplification is expected during upcoming decades. Conclusions are mapped from the Lena to other boreal discharges, and future research questions are outlined regarding the bonding type versus mass release as permafrost degrades. Dynamic aqueous organic coupling is recommended for polar system models, from headwaters to coastal diluent.
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Grace, Bryan L., and Thomas S. Bianchi. "Sorption and desorption dynamics of bulk dissolved organic matter and amino acids in the Mississippi River plume - a microcosm study." Marine and Freshwater Research 61, no. 9 (2010): 1067. http://dx.doi.org/10.1071/mf09181.
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Particulate and dissolved carbon, nitrogen and amino acids were analysed in a microcosm experiment where particulate material from the Mississippi River was mixed with surface waters of different salinities (2.0, 20.4 and 28.9) collected from the Mississippi River plume. There was evidence for the partitioning of amino acids in different salinity treatments during a 24-h period. Dissolved amino acids in the productive mid-salinity region of the plume had higher binding efficiencies than did amino acids from non-productive waters, indicative of the relative importance of phytoplankton sources of reactive amino acids. Basic amino acids were adsorbed more readily to particles, whereas acidic amino acids remained in the dissolved pool, indicating that electrostatic mechanisms affected amino-acid partitioning. Neutral amino-acid enrichment onto the particles was proportional to their respective hydrophobicity. Because riverine particles enter the higher salinity-shelf waters of the Mississippi River plume, changing ionic strength is a key in controlling amino-acid sorption and desorption kinetics. We propose that the short-term partitioning of amino acids between dissolved and particulate amino-acid pools across salinity gradients in the plume were affected by (1) electrostatic characteristics of suspended riverine sediment surfaces, (2) the availability of ‘freshly’ produced amino acids from phytoplankton and (3) the functional groups of amino acids.
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Moura, Rodrigo L., Gilberto M. Amado-Filho, Fernando C. Moraes, Poliana S. Brasileiro, Paulo S. Salomon, Michel M. Mahiques, Alex C. Bastos, et al. "An extensive reef system at the Amazon River mouth." Science Advances 2, no. 4 (April 2016): e1501252. http://dx.doi.org/10.1126/sciadv.1501252.
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Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 106–km2plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume’s eastward retroflection, conditions the existence of this extensive (~9500 km2) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth–ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.
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Parsons, Jeffrey D., John W. M. Bush, and James P. M. Syvitski. "Hyperpycnal plume formation from riverine outflows with small sediment concentrations." Sedimentology 48, no. 2 (April 6, 2001): 465–78. http://dx.doi.org/10.1046/j.1365-3091.2001.00384.x.
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Paulson, A. J., R. A. Feely, H. C. Curl, and D. A. Tennant. "Estuarine transport of trace metals in a buoyant riverine plume." Estuarine, Coastal and Shelf Science 28, no. 3 (March 1989): 231–48. http://dx.doi.org/10.1016/0272-7714(89)90015-2.
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Huang, W. J., W. J. Cai, Y. Wang, and C. S. Hopkinson. "Impacts of a weather event on shelf circulation and CO<sub>2</sub> and O<sub>2</sub> dynamics on the Louisiana shelf during summer 2009." Biogeosciences Discussions 10, no. 12 (December 17, 2013): 19867–93. http://dx.doi.org/10.5194/bgd-10-19867-2013.
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Abstract. While much is known about the physics of coastal currents, much less is known about the biogeochemical effects of surface currents on shelf carbon dioxide (CO2) and oxygen distribution and dynamics. The Mississippi and Atchafalaya River plume is usually observed along the Louisiana shelf with easterly winds. Such a typical pattern was observed in August 2007, i.e. a plume of low salinity and low partial pressure of CO2 (pCO2), indicating high biological production on the inner shelf; and higher salinity and pCO2 on the outer shelf. This high biological production induced by riverine nitrogen flux thus provided major organic matter sources for the shelf-wide hypoxia (dissolved oxygen [DO] < 2 mg L−1) accompanied by high dissolved inorganic carbon (DIC) concentrations in the bottom water. The slope of the DO and DIC relationship also demonstrated Redfield-type respiration in this shelf-wide hypoxia. In contrast, summer 2009 was an abnormal season characterized by a cool temperature in the central North America. Our observation and satellite chlorophyll a patterns both displayed a greatly distinct situation, i.e., the river plume was relocated to the eastern part of the Louisiana shelf; and high salinity and high pCO2 values occurred in surface waters of the western inner shelf. This plume relocation shifted the Louisiana shelf from a normally weak CO2 sink (as in 2007) to a strong CO2 source for the atmosphere. Although riverine nitrogen flux was enough to support a shelf-wide hypoxia in 2009, the plume relocation changed the location of high biological production and resulted in a limited hypoxic area. Furthermore, DIC concentration in bottom waters was higher than those predicted by the Redfield ratio, most likely because of much rapid O2 compensation than CO2 loss during air–sea exchange. Numerical models indicate such relocation of plume was mostly affected by the shelf circulation dominated by southerly and southwesterly winds. Consequently, we conclude that wind-forcing and shelf circulation are critical factors that influence the plume trajectories and the associated biogeochemical properties in coastal waters.
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MULLERKARULIS, B. "Transformations of riverine nutrients in the Daugava river plume (Gulf of Riga)." ICES Journal of Marine Science 56 (December 1999): 180–86. http://dx.doi.org/10.1006/jmsc.1999.0617.
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Herrera, Antonio, and David Bone. "Influence of riverine outputs on sandy beaches of Higuerote, central coast of Venezuela." Latin American Journal of Aquatic Research 39, no. 1 (November 11, 2011): 56–70. http://dx.doi.org/10.3856/vol39-issue1-fulltext-6.
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The influence of riverine outputs from the Tuy River on the coastal processes of near sandy beaches was assessed by measuring the physical and chemical characteristics of water and sediment samples at eight sites along the north central Venezuelan coast and from the rivers that flow through this region into the sea (Tuy, Capaya, Curiepe) during two field surveys. In addition, the behavior of the Tuy River discharge plume was evaluated using remote sensors, and its effect on the population abundance and size structure of the clam Tivela mactroides was determined. Of the three rivers evaluated, the Tuy River had the highest impact on the coastal zone (789.15 ± 190.63 km2) in terms of flow rate (246.39 m3 s-1), nutrients (659.61 ± 503.27 g s-1 total nitrogen; 52 ± 53.09 g s-1 total phosphorus) and sedimentary material (9320.84 ± 9728.15 g s-1). The variables measured (salinity, total nitrogen and phosphorus, pH, turbidity, and total organic carbon) showed a spatial gradient along the coast. Tivela mactroides had the highest biomass and density (9126.8 ± 1562 g m-2; 9222.22 ± 1976.72 ind m-2) at the sites farthest from the river mouths and smaller sizes (< 13 mm long) at sites close to the river mouths. The Tuy River plume modifies the functioning of the coastal system processes by discharging large amounts of nutrients and sedimentary material into the water column, which are then distributed by marine currents and alongshore transport. These contributions are used by T. mactroides populations, which show high abundances and differentiation in size structure along this coastline.
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Sandeep, K. K., and Vimlesh Pant. "Riverine freshwater plume variability in the Bay of Bengal using wind sensitivity experiments." Deep Sea Research Part II: Topical Studies in Oceanography 168 (October 2019): 104649. http://dx.doi.org/10.1016/j.dsr2.2019.104649.
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St. John, M. A., S. G. Marinone, J. Stronach, P. J. Harrison, J. Fyfe, and R. J. Beamish. "A Horizontally Resolving Physical–Biological Model of Nitrate Concentration and Primary Productivity in the Strait of Georgia." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 7 (July 1, 1993): 1456–66. http://dx.doi.org/10.1139/f93-166.
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Model simulations revealed that wind mixing was the dominant physical mechanism that added nitrate to the surface layer and subsequently enhanced primary productivity in the Strait of Georgia. Simulations of high Fraser River runoff showed that the enhanced stability of the water column in the vicinity of the riverine plume made wind mixing of nutrients into the surface layer more difficult. We propose that this increase in stability results in an earlier onset of the spring bloom in regions influenced by Fraser River runoff. During the summer, an increase in the buoyancy of surface water due to the freshwater plume reduces nitrate concentration in the surface layer and thereby limits primary production in the plume area. The reduced impact of wind events on nitrate fluxes is the result of a greater energy requirement to break down the more buoyant surface layer. Results indicate that during the fall, when light is again limiting and surface nitrate concentrations increase due to wind mixing by fall storms, the freshwater runoff from the Fraser River results in a more stable water column (similar to the spring situation) in the southern Strait, resulting in the potential for a fall bloom.
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Wang, Suisui, Kalyani Sen, Yaodong He, Mohan Bai, and Guangyi Wang. "Riverine Inputs Impact the Diversity and Population Structure of Heterotrophic Fungus-like Protists and Bacterioplankton in the Coastal Waters of the South China Sea." Water 14, no. 10 (May 15, 2022): 1580. http://dx.doi.org/10.3390/w14101580.
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Labyrinthulomycetes protists (LP) play an important role in ocean carbon cycling with an ubiquitous presence in marine ecosystems. As one of the most important environmental factors, salinity is known to regulate their diverse metabolic activities. However, impacts of salinity gradient on their distribution and ecological functions in natural habitats remain largely unknown. In this study, the dynamics of LP abundance and community structure were examined in the surface water of plume, offshore, and pelagic habitats in the South China Sea (SCS). The highest (5.59 × 105 copies L−1) and lowest (5.28 × 104 copies L−1) abundance of LP were found to occur in the waters of plume and pelagic habitats, respectively. Multiple dimensional scaling (MDS) analysis revealed a strong relationship between salinity and LP community variation (p < 0.05, rho = 0.67). Unexpectedly, relative low LP diversity was detected in the brackish water samples of the plume. Moreover, our results indicated the genus Aplanochytrium dominated LP communities in offshore and pelagic, while Aurantiochytrium and Ulkenia were common in the plume. Physiological and metabolic features of these genera suggested that LP ecological functions were also largely varied along this salinity gradient. Clearly, the salinity gradient likely regulates the diversity and functional partitioning of marine protistan micro-eukaryotes in the world’s oceans.
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ZHANG, MINGRUI, LAWRENCE O. HALL, DMITRY B. GOLDGOF, and FRANK E. MÜLLER-KARGER. "KNOWLEDGE-GUIDED CLASSIFICATION OF COASTAL ZONE COLOR IMAGES OFF THE WEST FLORIDA SHELF." International Journal of Pattern Recognition and Artificial Intelligence 14, no. 08 (December 2000): 987–1007. http://dx.doi.org/10.1142/s0218001400000660.
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A knowledge-guided approach to automatic classification of Coastal Zone Color images off the West Florida Shelf is described. The approach is used to identify red tides on the West Florida Shelf, as well as areas with high concentration of dissolved organic matter such as a river plume found seasonally along the West Florida coast over the middle of the shelf. The Coastal Zone Color images are initially segmented by the unsupervised Multistage Random Sampling Fuzzy c-Means algorithm. Then, a knowledge-guided system is applied to the centroid values of resultant clusters to label case I, case II waters, a dilute river plume ("green river"), and red tide. The domain knowledge base contains information on cluster distribution in feature space, as well as spatial information such as bathymetry data. Our knowledge base consists of a rule-guided system and an embedded neural network. From 60 images, after training the system, this procedure recognizes all 15 images which contained a river plume and 45 images without. The system can correctly classify 74% of the pixels that belong to the river plume, which provides a substantial advantage to users looking for offshore extensions of riverine influence. Red tides are also successfully identified in a time series of images for which ground truth confirmed the presence of a harmful bloom.
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Fukuwaka, M., and T. Suzuki. "Role of a riverine plume as a nursery area for chum salmon Oncorhynchus keta." Marine Ecology Progress Series 173 (1998): 289–97. http://dx.doi.org/10.3354/meps173289.
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Hu, Didi, Min Xu, Shichang Kang, Jinlei Chen, Chengde Yang, and Qian Yang. "The Effects of Discharge Changes in Siberian Rivers on Arctic Sea-Ice Melting." Remote Sensing 15, no. 14 (July 10, 2023): 3477. http://dx.doi.org/10.3390/rs15143477.
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Arctic river discharge is one of the important factors affecting sea-ice melting of Arctic shelf seas. However, such effects have not been given much attention. In this study, the changes in discharge of the Ob, Yenisei, and Lena Rivers and the sea ice of the Kara and Laptev Seas during 1979–2019 were analyzed. Substantial increases in discharge and heat from the discharge and decreases in sea ice concentration (SIC) were detected. The effects of changes in discharge and riverine heat on sea ice changes were investigated. The results showed that the influence of the discharge, accumulated discharge, heat, and accumulated heat on SIC mainly occurred at the beginning and final stages of sea-ice melting. Discharge accelerated the melting of sea ice by increasing the absorption of solar radiation as the impurities contained in the discharge washed to the sea ice surface during the initial and late stages of sea-ice melting. Changes in cumulative riverine heat from May to September greatly contributed to the SIC changes in the Kara and Laptev Seas at the seasonal scale. The SIC reduced by 1% when the cumulative riverine heat increased by 213.2 × 106 MJ, 181.5 × 106 MJ, and 154.6 × 106 MJ in the Lena, Yenisei, and Ob Rivers, respectively, from May to September. However, even in the plume coverage areas in the Kara and Laptev Seas, discharge changes from the three rivers had a limited contribution to the reduction in SIC at annual scales. This work is helpful for understanding the changes in Arctic sea ice.
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PAVLIDOU, A., I. HATZIANESTIS, E. SKLIVAGOU, V. PAPADOPOULOS, and V. ZERVAKIS. "Hydrology and pollution assessment in a coastal estuarine system. The case of the Strymonikos Gulf (North Aegean Sea)." Mediterranean Marine Science 3, no. 1 (June 1, 2002): 65. http://dx.doi.org/10.12681/mms.259.
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Three hydrographic cruises were undertaken to study the hydrology and to estimate the ecological status of the coastal ecosystem of the Strymonikos Gulf (North Aegean Sea) impacted by the riverine waters of the Strymon River. Surface sediments were also collected in order to determine the levels of organic contaminants in the gulf. Three main water masses were identified in the Strymonikos Gulf throughout the year: a) the surface river plume water, b) the surface and subsurface Black Sea Water and c) the near bottom (>50 m) water of Levantine origin. High nutrient concentrations were recorded close to the mouth of the river, indicating a rather eutrophic environment, which was restricted near the river discharge. The salinity-nutrient correlations of the surface waters of the study area were linear, indicating that the riverine waters are the major source of nutrient in the gulf. DIN:P ratios varied seasonally from relatively higher values during winter and early spring to lower values in late spring-early summer. This led to a shift from likelihood P-limitation during winter and early spring to N-limitation in late spring – early summer. Total hydrocarbon concentrations measured in the sediments ranged from 19.2 to 95.9 μ g/g, whereas total polycyclic aromatic hydrocarbon (PAH) values varied between 107.2 and 1019 ng/g. The application of different diagnostic criteria suggests a natural terrestrial origin for aliphatic hydrocarbons and pyrolytic origin for the PAHs. DDTs displayed the highest concentrations of all the organochlorines determined, whereas polychlorinated biphenyl (PCBs) concentrations were very low. Riverine input seems to be the major source for all the compounds identified.
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Devlin, M. J., L. W. McKinna, J. G. Álvarez-Romero, C. Petus, B. Abott, P. Harkness, and J. Brodie. "Mapping the pollutants in surface riverine flood plume waters in the Great Barrier Reef, Australia." Marine Pollution Bulletin 65, no. 4-9 (2012): 224–35. http://dx.doi.org/10.1016/j.marpolbul.2012.03.001.
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Conrad, Sarah, Johan Ingri, Johan Gelting, Fredrik Nordblad, Emma Engström, Ilia Rodushkin, Per S. Andersson, et al. "Distribution of Fe isotopes in particles and colloids in the salinity gradient along the Lena River plume, Laptev Sea." Biogeosciences 16, no. 6 (March 28, 2019): 1305–19. http://dx.doi.org/10.5194/bg-16-1305-2019.
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Abstract. Riverine Fe input is the primary Fe source for the ocean. This study is focused on the distribution of Fe along the Lena River freshwater plume in the Laptev Sea using samples from a 600 km long transect in front of the Lena River mouth. Separation of the particulate (>0.22 µm), colloidal (0.22 µm–1 kDa), and truly dissolved (<1 kDa) fractions of Fe was carried out. The total Fe concentrations ranged from 0.2 to 57 µM with Fe dominantly as particulate Fe. The loss of >99 % of particulate Fe and about 90 % of the colloidal Fe was observed across the shelf, while the truly dissolved phase was almost constant across the Laptev Sea. Thus, the truly dissolved Fe could be an important source of bioavailable Fe for plankton in the central Arctic Ocean, together with the colloidal Fe. Fe-isotope analysis showed that the particulate phase and the sediment below the Lena River freshwater plume had negative δ56Fe values (relative to IRMM-14). The colloidal Fe phase showed negative δ56Fe values close to the river mouth (about −0.20 ‰) and positive δ56Fe values in the outermost stations (about +0.10 ‰). We suggest that the shelf zone acts as a sink for Fe particles and colloids with negative δ56Fe values, representing chemically reactive ferrihydrites. The positive δ56Fe values of the colloidal phase within the outer Lena River freshwater plume might represent Fe oxyhydroxides, which remain in the water column, and will be the predominant δ56Fe composition in the Arctic Ocean.
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Wegner, C., D. Bauch, J. A. Hölemann, M. A. Janout, B. Heim, A. Novikhin, S. Kirillov, H. Kassens, and L. Timokhov. "Interannual variability of surface and bottom sediment transport on the Laptev Sea shelf during summer." Biogeosciences Discussions 9, no. 9 (September 20, 2012): 13053–84. http://dx.doi.org/10.5194/bgd-9-13053-2012.
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Abstract. Sediment transport dynamics were studied during ice-free conditions under different atmospheric circulation regimes on the Laptev Sea shelf (Siberian Arctic). To study the interannual variability of suspended particulate matter (SPM) dynamics and their coupling with the variability in surface river water distribution on the Laptev Sea detailed oceanographic, optical (turbidity and Ocean Color satellite data), and hydrochemical (nutrients, SPM, stable oxygen isotopes) process studies were carried out continuously during the summers of 2007 and 2008. Thus, for the first time SPM and nutrient variations on the Laptev Sea shelf under different atmospheric forcing and the implications for the turbidity and transparency of the water column can be presented. The data indicate a clear link between different surface distributions of riverine waters and the SPM transport dynamics within the entire water column. The summer of 2007 was dominated by shoreward winds and an eastward transport of riverine surface waters. The surface SPM concentration on the south-eastern inner shelf was elevated, which led to decreased transmissivity and increased light absorption. Surface SPM concentrations in the Central and Northern Laptev Sea were comparatively low. However, the SPM transport and concentration within the bottom nepheloid layer increased considerably on the entire eastern shelf. The summer of 2008 was dominated by offshore-winds and northwards transport of the river plume. The surface SPM transport was enhanced and extended onto the mid-shelf whereas the bottom SPM transport and concentration was diminished. This study suggests that the SPM concentration and transport in both, the surface and bottom nepheloid layers, are associated with the distribution of riverine surface waters which are linked to the atmospheric circulation patterns over the Laptev Sea and the adjacent Arctic Ocean during open water season. A continuing trend toward shoreward winds, weaker stratification and higher SPM concentration throughout the water column might have severe consequences for the ecosystem on the Laptev Sea shelf.
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Wegner, C., D. Bauch, J. A. Hölemann, M. A. Janout, B. Heim, A. Novikhin, H. Kassens, and L. Timokhov. "Interannual variability of surface and bottom sediment transport on the Laptev Sea shelf during summer." Biogeosciences 10, no. 2 (February 20, 2013): 1117–29. http://dx.doi.org/10.5194/bg-10-1117-2013.
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Abstract. Sediment transport dynamics were studied during ice-free conditions under different atmospheric circulation regimes on the Laptev Sea shelf (Siberian Arctic). To study the interannual variability of suspended particulate matter (SPM) dynamics and their coupling with the variability in surface river water distribution on the Laptev Sea shelf, detailed oceanographic, optical (turbidity and Ocean Color satellite data), and hydrochemical (nutrients, SPM, stable oxygen isotopes) process studies were carried out continuously during the summers of 2007 and 2008. Thus, for the first time SPM and nutrient variations on the Laptev Sea shelf under different atmospheric forcing and the implications for the turbidity and transparency of the water column can be presented. The data indicate a clear link between different surface distributions of riverine waters and the SPM transport dynamics within the entire water column. The summer of 2007 was dominated by shoreward winds and an eastward transport of riverine surface waters. The surface SPM concentration on the southeastern inner shelf was elevated, which led to decreased transmissivity and increased light absorption. Surface SPM concentrations in the central and northern Laptev Sea were comparatively low. However, the SPM transport and concentration within the bottom nepheloid layer increased considerably on the entire eastern shelf. The summer of 2008 was dominated by offshore winds and northward transport of the river plume. The surface SPM transport was enhanced and extended onto the mid-shelf, whereas the bottom SPM transport and concentration was diminished. This study suggests that the SPM concentration and transport, in both the surface and bottom nepheloid layers, are associated with the distribution of riverine surface waters which are linked to the atmospheric circulation patterns over the Laptev Sea and the adjacent Arctic Ocean during the open water season. A continuing trend toward shoreward winds, weaker stratification and higher SPM concentration throughout the water column might have severe consequences for the ecosystem on the Laptev Sea shelf.
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Cepīte-Frišfelde, Daiga, Andrejs Timuhins, and Vilnis Frišfelds. "Modeled surface salinity and satellite data as proxy for Secchi depth and watercolor of the Gulf of Riga." E3S Web of Conferences 436 (2023): 10001. http://dx.doi.org/10.1051/e3sconf/202343610001.
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The present study pays attention to the sea surface salinity field and satellite derived watercolor and Secchi depth datasets in the Gulf of Riga in 1998-2018. The study increases understanding of the river plume’s impact on the open part of the Gulf of Riga. Mean watercolor and salinity versus depth had been compared in April and August month. The region with the high mean watercolor and salinity homogeneity consistency had been seen in the deepest part (depth >40m) of the Gulf of Riga in April. The correlation between mean salinity field and watercolor and Secchi depth data sets had been shown. It marks the coastal and transitional region where the current of riverine water on the sea surface dominate the upwelling from the more saline deeper layers. The study distinguishes mean watercolor (in situ observations and derived from satellite) in years with and without seasonal hypoxia in the Gulf of Riga in 2005-2018. Convincing difference between both sets have not been found.
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Bernard, C. Y., H. H. Dürr, C. Heinze, J. Segschneider, and E. Maier-Reimer. "Contribution of riverine nutrients to the silicon biogeochemistry of the global ocean – a model study." Biogeosciences Discussions 6, no. 1 (January 21, 2009): 1091–119. http://dx.doi.org/10.5194/bgd-6-1091-2009.
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Abstract. Continental shelf seas are known to support a large fraction of the global primary production. Yet, continental shelf areas are mostly ignored or neglected in global biogeochemical models. A number of processes that control the transfer of dissolved nutrients from river to the open ocean remain poorly understood. This applies in particular to dissolved silica which drives the growth of diatoms that form a large part of the phytoplankton biomass and are thus an important contributor to export production of carbon. Here, the representation of the biogeochemical state along continents is improved by coupling a high resolution database of riverine fluxes of nutrients to the global biogeochemical ocean general circulation model MPI-OM/HAMOCC5. Focusing on silicon (Si), but including the whole suite of nutrients – carbon (C), nitrogen (N) and phosphorus (P) in various forms – inputs are implemented in the model at coastal coupling points using the COSCAT global database of 156 mega-river-ensemble catchments from Meybeck et al. (2006). The catchments connect to the ocean through coastal segments according to three sets of criteria: natural limits, continental shelf topography, and geophysical dynamics. According to the model the largest effects on nutrient concentrations occur in hot spots such as the Amazon plume, the Arctic – with high nutrient inputs in relation to its total volume, and areas that encounter the largest increase in human activity, e.g., Southern Asia.
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Bernard, C. Y., H. H. Dürr, C. Heinze, J. Segschneider, and E. Maier-Reimer. "Contribution of riverine nutrients to the silicon biogeochemistry of the global ocean – a model study." Biogeosciences Discussions 7, no. 3 (June 25, 2010): 4919–51. http://dx.doi.org/10.5194/bgd-7-4919-2010.
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Abstract. Continental shelf seas are known to support a large fraction of the global primary production. Yet, continental shelf areas are mostly ignored or neglected in global biogeochemical models. A number of processes that control the transfer of dissolved nutrients from rivers to the open ocean remain poorly understood. This applies in particular to dissolved silica which drives the growth of diatoms that form a large part of the phytoplankton biomass and are thus an important contributor to export production of carbon. Here, the representation of the biogeochemical cycling along continents is improved by coupling a high resolution database of riverine fluxes of nutrients to the global biogeochemical ocean general circulation model HAMOCC5-OM. Focusing on silicon (Si), but including the whole suite of nutrients – carbon (C), nitrogen (N) and phosphorus (P) in various forms – inputs are implemented in the model at coastal coupling points using the COSCAT global database of 156 mega-river-ensemble catchments from Meybeck et al. (2006). The catchments connect to the ocean through coastal segments according to three sets of criteria: natural limits, continental shelf topography, and geophysical dynamics. According to the model the largest effects on nutrient concentrations occur in hot spots such as the Amazon plume, the Arctic – with high nutrient inputs in relation to its total volume, and areas that encounter the largest increase in human activity, e.g., Southern Asia.
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Bernard, C. Y., H. H. Dürr, C. Heinze, J. Segschneider, and E. Maier-Reimer. "Contribution of riverine nutrients to the silicon biogeochemistry of the global ocean – a model study." Biogeosciences 8, no. 3 (March 4, 2011): 551–64. http://dx.doi.org/10.5194/bg-8-551-2011.
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Abstract. Continental shelf seas are known to support a large fraction of the global primary production. Yet, they are mostly ignored or neglected in global biogeochemical models. A number of processes that control the transfer of dissolved nutrients from rivers to the open ocean remain poorly understood. This applies in particular to dissolved silica which drives the growth of diatoms that form a large part of the phytoplankton biomass and are thus an important contributor to export production of carbon. Here, the representation of the biogeochemical cycling along continents is improved by coupling a high resolution database of riverine fluxes of nutrients to the global biogeochemical ocean general circulation model HAMOCC5-OM. Focusing on silicon (Si), but including the whole suite of nutrients – carbon (C), nitrogen (N) and phosphorus (P) in various forms – inputs are implemented in the model at coastal coupling points using the COSCAT global database of 156 mega-river-ensemble catchments from Meybeck et al. (2006). The catchments connect to the ocean through coastal segments according to three sets of criteria: natural limits, continental shelf topography, and geophysical dynamics. According to the model the largest effects on nutrient concentrations occur in hot spots such as the Amazon plume, the Arctic – with high nutrient inputs in relation to its total volume, and areas that encounter the largest increase in human activity, e.g., Southern Asia.
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Brodeur, R. D., and C. A. Morgan. "Influence of a Coastal Riverine Plume on the Cross-shelf Variability in Hydrography, Zooplankton, and Juvenile Salmon Diets." Estuaries and Coasts 39, no. 4 (December 9, 2015): 1183–98. http://dx.doi.org/10.1007/s12237-015-0050-4.
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Zhang, Haiyan, Katja Fennel, Arnaud Laurent, and Changwei Bian. "A numerical model study of the main factors contributing to hypoxia and its interannual and short-term variability in the East China Sea." Biogeosciences 17, no. 22 (November 23, 2020): 5745–61. http://dx.doi.org/10.5194/bg-17-5745-2020.
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Abstract. A three-dimensional physical-biological model of the marginal seas of China was used to analyze interannual and intra-seasonal variations in hypoxic conditions and identify the main processes controlling their generation off the Changjiang (or Yangtze River) estuary. The model was compared against available observations and reproduces the observed temporal and spatial variability of physical and biological properties including bottom oxygen. Interannual variations of hypoxic extent in the simulation are partly explained by variations in river discharge but not nutrient load. As riverine inputs of freshwater and nutrients are consistently high, promoting large productivity and subsequent oxygen consumption in the region affected by the river plume, wind forcing is important in modulating interannual and short-term variability. Wind direction is relevant because it determines the spatial extent and distribution of the freshwater plume, which is strongly affected by either upwelling or downwelling conditions. High-wind events can lead to partial reoxygenation of bottom waters and, when occurring in succession throughout the hypoxic season, can effectively suppress the development of hypoxic conditions, thus influencing interannual variability. A model-derived oxygen budget is presented and suggests that sediment oxygen consumption is the dominant oxygen sink below the pycnocline and that advection of oxygen in the bottom waters acts as an oxygen sink in spring but becomes a source during hypoxic conditions in summer, especially in the southern part of the hypoxic region, which is influenced by open-ocean intrusions.
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Thorrold, Simon R., and A. David McKinnon. "Response of larval fish assemblages to a riverine plume in coastal waters of the central Great Barrier Reef lagoon." Limnology and Oceanography 40, no. 1 (January 1995): 177–81. http://dx.doi.org/10.4319/lo.1995.40.1.0177.
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Häggi, C., C. M. Chiessi, and E. Schefuß. "Testing the D / H ratio of alkenones and palmitic acid as salinity proxies in the Amazon Plume." Biogeosciences 12, no. 23 (December 10, 2015): 7239–49. http://dx.doi.org/10.5194/bg-12-7239-2015.
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Abstract. The stable hydrogen isotope composition of lipid biomarkers, such as alkenones, is a promising new tool for the improvement of palaeosalinity reconstructions. Laboratory studies confirmed the correlation between lipid biomarker δD composition (δDLipid), water δD composition (δDH2O) and salinity; yet there is limited insight into the applicability of this proxy in oceanic environments. To fill this gap, we test the use of the δD composition of alkenones (δDC37) and palmitic acid (δDPA) as salinity proxies using samples of surface suspended material along the distinct salinity gradient induced by the Amazon Plume. Our results indicate a positive correlation between salinity and δDH2O, while the relationship between δDH2O and δDLipid is more complex: δDPAM correlates strongly with δDH2O (r2 = 0.81) and shows a salinity-dependent isotopic fractionation factor. δDC37 only correlates with δDH2O in a small number (n = 8) of samples with alkenone concentrations > 10 ng L−1, while there is no correlation if all samples are taken into account. These findings are mirrored by alkenone-based temperature reconstructions, which are inaccurate for samples with low alkenone concentrations. Deviations in δDC37 and temperature are likely to be caused by limited haptophyte algae growth due to low salinity and light limitation imposed by the Amazon Plume. Our study confirms the applicability of δDLipid as a salinity proxy in oceanic environments. But it raises a note of caution concerning regions where low alkenone production can be expected due to low salinity and light limitation, for instance, under strong riverine discharge.
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Hoshiba, Yasuhiro, Yoshimasa Matsumura, Hiroyasu Hasumi, Sachihiko Itoh, Satoshi Nakada, and Keita W. Suzuki. "A simulation study on effects of suspended sediment through high riverine discharge on surface river plume and vertical water exchange." Estuarine, Coastal and Shelf Science 228 (November 2019): 106352. http://dx.doi.org/10.1016/j.ecss.2019.106352.
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Liu, Q., M. Dai, W. Chen, C. A. Huh, G. Wang, Q. Li, and M. A. Charette. "How significant is submarine groundwater discharge and its associated dissolved inorganic carbon in a river-dominated shelf system-the northern South China Sea?" Biogeosciences Discussions 8, no. 6 (December 21, 2011): 12381–422. http://dx.doi.org/10.5194/bgd-8-12381-2011.
Full textAbstract:
Abstract. In order to assess the role of submarine groundwater discharge (SGD) and its impact on the carbonate system on the northern South China Sea (NSCS) shelf, we measured seawater concentrations of four radium isotopes 223,224,226,228Ra along with carbon dioxide parameters in June–July, 2008. Complementary groundwater sampling was conducted in coastal areas in December 2008 and October 2010 to constrain the groundwater end-members. The distribution of Ra isotopes in the NSCS was largely controlled by the Pearl River plume and coastal upwelling. Long-lived Ra isotopes (228Ra and 226Ra) were enriched in the river plume but low in the offshore surface water and subsurface water/upwelling zone. In contrast, short-lived Ra isotopes (224Ra and 223Ra) were elevated in the subsurface water/upwelling zone as well as the river plume but depleted in the offshore surface water. In order to quantify SGD, we adopted two independent mathematical approaches. Using a three end-member mixing model with total alkalinity (TAlk) and Ra isotopes, we derived a SGD flux into the NSCS shelf of 2.3–3.7 ×108 m3 d−1. Our second approach involved a simple mass balance of 228Ra and 226Ra and resulted in a first order but consistent SGD rate estimate of 2.8–4.5 × 108 m3 d−1. These fluxes were equivalent to 13–25 % of the Pearl River discharge, but the source of the SGD is mostly recirculated seawater. Despite the relatively small SGD volume flow compared to the river, the associated material fluxes were substantial given the elevated concentrations of dissolved inorganic solutes. In this case, dissolved inorganic carbon (DIC) flux through SGD was 266–520 × 109 mol yr−1, which was ~44–73 % of the riverine DIC export flux. Given our estimates of the groundwater-derived phosphate flux, SGD may be responsible for new production on the shelf up to 3–6 mmol C m−2 d−1. This rate of new production would at most consume 18 % of the DIC contribution delivered by SGD. Hence, SGD may play an important role in the carbon balance over the NSCS shelf.
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Maguire, Timothy J., Craig A. Stow, and Casey M. Godwin. "Spatially referenced Bayesian state-space model of total phosphorus in western Lake Erie." Hydrology and Earth System Sciences 26, no. 8 (April 25, 2022): 1993–2017. http://dx.doi.org/10.5194/hess-26-1993-2022.
Full textAbstract:
Abstract. Collecting water quality data across large lakes is often done under regulatory mandate; however, it is difficult to connect nutrient concentration observations to sources of those nutrients and to quantify this relationship. This difficulty arises from the spatial and temporal separation between observations, the impact of hydrodynamic forces, and the cost involved in discrete samples collected aboard vessels. These challenges are typified in Lake Erie, where binational agreements regulate riverine loads of total phosphorus (TP) to address the impacts from annual harmful algal blooms (HABs). While it is known that the Maumee River supplies 50 % of the nutrient load to Lake Erie, the details of how the Maumee River TP load changes Lake Erie TP concentration have not been demonstrated. We developed a hierarchical spatially referenced Bayesian state-space model with an adjacency matrix defined by surface currents. This was applied to a 2 km-by-2 km grid of nodes, to which observed lake and river TP concentrations were joined. The model generated posterior samples describing the unobserved nodes and observed nodes on unobserved days. We quantified the impact plume of the Maumee River by experimentally changing concentration data and tracking the change in in-lake predictions. Our impact plume represents the spatial and temporal variation of how river concentrations correlate with lake concentrations. We used the impact plume to scale the Maumee River spring TP load to an effective Maumee River TP spring load for each node in the lake. By assigning an effective load to each node, the relationship between load and concentration is consistent throughout our sampling locations. A linear model of annual lake node mean TP concentration and effective Maumee River load estimated that, in the absence of the Maumee River load, lake concentrations at the sampled nodes would be 23.1 µg L−1 (±1.75, 95 % CI, credible interval) and that for each 100 t of spring TP effective load delivered to Lake Erie, mean TP concentrations increase by 11 µg L−1 (±1, 95 % CI). Our proposed modeling technique allowed us to establish these quantitative connections between Maumee TP load and Lake Erie TP concentrations which otherwise would be masked by the movement of water through space and time.
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Maguire, Timothy J., Craig A. Stow, and Casey M. Godwin. "Spatially referenced Bayesian state-space model of total phosphorus in western Lake Erie." Hydrology and Earth System Sciences 26, no. 8 (April 25, 2022): 1993–2017. http://dx.doi.org/10.5194/hess-26-1993-2022.
Full textAbstract:
Abstract. Collecting water quality data across large lakes is often done under regulatory mandate; however, it is difficult to connect nutrient concentration observations to sources of those nutrients and to quantify this relationship. This difficulty arises from the spatial and temporal separation between observations, the impact of hydrodynamic forces, and the cost involved in discrete samples collected aboard vessels. These challenges are typified in Lake Erie, where binational agreements regulate riverine loads of total phosphorus (TP) to address the impacts from annual harmful algal blooms (HABs). While it is known that the Maumee River supplies 50 % of the nutrient load to Lake Erie, the details of how the Maumee River TP load changes Lake Erie TP concentration have not been demonstrated. We developed a hierarchical spatially referenced Bayesian state-space model with an adjacency matrix defined by surface currents. This was applied to a 2 km-by-2 km grid of nodes, to which observed lake and river TP concentrations were joined. The model generated posterior samples describing the unobserved nodes and observed nodes on unobserved days. We quantified the impact plume of the Maumee River by experimentally changing concentration data and tracking the change in in-lake predictions. Our impact plume represents the spatial and temporal variation of how river concentrations correlate with lake concentrations. We used the impact plume to scale the Maumee River spring TP load to an effective Maumee River TP spring load for each node in the lake. By assigning an effective load to each node, the relationship between load and concentration is consistent throughout our sampling locations. A linear model of annual lake node mean TP concentration and effective Maumee River load estimated that, in the absence of the Maumee River load, lake concentrations at the sampled nodes would be 23.1 µg L−1 (±1.75, 95 % CI, credible interval) and that for each 100 t of spring TP effective load delivered to Lake Erie, mean TP concentrations increase by 11 µg L−1 (±1, 95 % CI). Our proposed modeling technique allowed us to establish these quantitative connections between Maumee TP load and Lake Erie TP concentrations which otherwise would be masked by the movement of water through space and time.
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Liu, Q., M. Dai, W. Chen, C. A. Huh, G. Wang, Q. Li, and M. A. Charette. "How significant is submarine groundwater discharge and its associated dissolved inorganic carbon in a river-dominated shelf system?" Biogeosciences 9, no. 5 (May 22, 2012): 1777–95. http://dx.doi.org/10.5194/bg-9-1777-2012.
Full textAbstract:
Abstract. In order to assess the role of submarine groundwater discharge (SGD) and its impact on the carbonate system on the northern South China Sea (NSCS) shelf, we measured seawater concentrations of four radium isotopes 223,224,226,228Ra along with carbonate system parameters in June–July, 2008. Complementary groundwater sampling was conducted in coastal areas in December 2008 and October 2010 to constrain the groundwater end-members. The distribution of Ra isotopes in the NSCS was largely controlled by the Pearl River plume and coastal upwelling. Long-lived Ra isotopes (228Ra and 226Ra) were enriched in the river plume but low in the offshore surface water and subsurface water/upwelling zone. In contrast, short-lived Ra isotopes (224Ra and 223Ra) were elevated in the subsurface water/upwelling zone as well as in the river plume but depleted in the offshore surface water. In order to quantify SGD, we adopted two independent mathematical approaches. Using a three end-member mixing model with total alkalinity (TAlk) and Ra isotopes, we derived a SGD flux into the NSCS shelf of 2.3–3.7 × 108 m3 day−1. Our second approach involved a simple mass balance of 228Ra and 226Ra and resulted in a first order but consistent SGD flux estimate of 2.2–3.7 × 108 m3 day−1. These fluxes were equivalent to 12–21 % of the Pearl River discharge, but the source of the SGD was mostly recirculated seawater. Despite the relatively small SGD volume flow compared to the river, the associated material fluxes were substantial given their elevated concentrations of dissolved inorganic solutes. In this case, dissolved inorganic carbon (DIC) flux through SGD was 153–347 × 109 mol yr−1, or ~23–53 % of the riverine DIC export flux. Our estimates of the groundwater-derived phosphate flux ranged 3–68 × 107 mol yr−1, which may be responsible for new production on the shelf up to 0.3–6.3 mmol C m−2 d−1. This rate of new production would at most consume 11 % of the DIC contribution delivered by SGD. Hence, SGD may play an important role in the carbon balance over the NSCS shelf.