Nutrient behavior in a highly-eutrophicated tropical estuarine system

Abstract Aim: There are few studies dealing with the biogeochemical processes occurring in small estuaries receiving high sewage loading in tropical regions. The aim of this investigation was to characterize the biogeochemical behavior of nutrients in superficial waters collected at the Iguaçu estuarine system, during specific conditions (neap tide), located at the inner sector of a heavily eutrophicated embayment (Guanabara Bay, SE Brazil). Methods Physical and chemical variables were measured in situ (pH, temperature, conductivity, salinity, total dissolved solids, transparency, dissolved oxygen), whereas suspended particulate matter, chlorophyll a, phaepigments and nutrients (carbon, nitrogen and phosphorus forms) were measured in laboratory across the mesohaline estuarine gradient. Results The Iguaçu River mouth is in a high stage of eutrophication, considering nutrient concentrations, chlorophyll a and transparency of water column. Results indicate a transition from heterotrophic conditions to autotrophic conditions, since the nutrients concentrations showed a decreasing pattern along the saline gradient, while the chlorophyll an increased over the transects. The pH values and chlorophyll : phaeopigments ratios are significantly related to the amount and quality of organic matter contents, especially at transects under strong marine influence. More than 95% of the dissolved and total nitrogen concentrations are represented by NH4+ contributions, which are related to the ammonification of organic matter contents in this region, indicating the existence of untreated sewage loads in this area. Conclusion In this study, the Iguaçu River seemed to contribute with high inputs of nutrients that support important phytoplankton production at the inner regions of the bay related to the CO2 sink and autotrophic metabolism, showing the importance of verifying the biogeochemical behaviors of nutrients in estuarine areas, even in small scale.

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Distribution of inorganic and organic nutrients in the South Pacific Ocean − evidence for long-term accumulation of organic matter in nitrogen-depleted waters

Biogeosciences ◽

10.5194/bg-5-281-2008 ◽

2008 ◽

Vol 5 (2) ◽

pp. 281-298 ◽

Cited By ~ 83

Author(s):

P. Raimbault ◽

N. Garcia ◽

F. Cerutti

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Dissolved Organic Matter ◽

Dissolved Organic Carbon ◽

Chlorophyll A ◽

Organic Phosphorus ◽

South Pacific ◽

Nutrient Concentrations ◽

The South ◽

Photic Layer

Abstract. During the BIOSOPE cruise the RV Atalante was dedicated to study the biogeochemical properties in the South Pacific between the Marquesas Islands (141° W–8° S) and the Chilean upwelling (73° W–34° S). Over the 8000 km covered by the cruise, several different trophic situations were encountered, in particular strong oligotrophic conditions in the South Pacific Gyre (SPG, between 123° W and 101° W). In this isolated region, nitrate was undetectable between the surface and 160–180 m and only trace quantities (<20 nmoles l−1) of regenerated nitrogen (nitrite and ammonium) were detected, even in the subsurface maximum. Integrated nitrate over the photic layer, which reached 165 m, was close to zero. Despite this severe nitrogen-depletion, phosphate was always present in significant concentrations (≈0.1 μmoles l−1), while silicic acid was maintained at low but classical oceanic levels (≈1 μmoles l−1). In contrast, the Marquesas region (MAR) to the west and Chilean upwelling (UPW) to the east were characterized by high nutrient concentrations, one hundred to one thousand fold higher than in the SPG. The distribution of surface chlorophyll reflected the nitrate gradient, the lowest concentrations (0.023 nmoles l−1) being measured at the centre of the SPG, where integrated value throughout the photic layer was very low (≈ 10 mg m−2). However, due to the relatively high concentrations of chlorophyll-a encountered in the DCM (0.2 μg l−1), chlorophyll-a concentrations throughout the photic layer were less variable than nitrate concentrations (by a factor 2 to 5). In contrast to chlorophyll-a, integrated particulate organic matter (POM) remained more or less constant along the study area (500 mmoles m−2, 60 mmoles m−2 and 3.5 mmoles m−2 for particulate organic carbon, particulate organic nitrogen and particulate organic phosphorus, respectively), with the exception of the upwelling, where values were two fold higher. The residence time of particulate carbon in the surface water was only 4–5 days in the upwelling, but up to 30 days in the SPG, where light isotopic δ15N signal noted in the suspended POM suggests that N2-fixation provides a dominant supply of nitrogen to phytoplankton. The most striking feature was the large accumulation of dissolved organic matter (DOM) in the SPG compared to the surrounding waters, in particular dissolved organic carbon (DOC) where concentrations were at levels rarely measured in oceanic waters (>100 μmoles l−1). Due to this large pool of DOM in the SPG photic layer, integrated values followed a converse geographical pattern to that of inorganic nutrients with a large accumulation in the centre of the SPG. Whereas suspended particulate matter in the mixed layer had a C/N ratio largely conforming to the Redfield stochiometry (C/N≈6.6), marked deviations were observed in this excess DOM (C/N≈16 to 23). The marked geographical trend suggests that a net in situ source exists, mainly due to biological processes. Thus, in spite of strong nitrate-depletion leading to low chlorophyll biomass, the closed ecosystem of the SPG can accumulate large amounts of C-rich dissolved organic matter. The implications of this finding are examined, the conclusion being that, due to weak lateral advection, the biologically produced dissolved organic carbon can be accumulated and stored in the photic layer for very long periods. In spite of the lack of seasonal vertical mixing, a significant part of new production (up to 34%), which was mainly supported by dinitrogen fixation, can be exported to deep waters by turbulent diffusion in terms of DOC. The diffusive rate estimated in the SPG (134 μmolesC m−2 d−1), was quite equivalent to the particles flux measured by sediments traps.

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SECTOR ORIENTAL DEL GOLFO DE CARIACO, VENEZUELA. UNA DESCRIPCIÓN DE SU DINÁMICA HIDROQUÍMICA, PROCESOS, Y DEL ROL DE LA SURGENCIA COSTERA ESTACIONAL

10.31219/osf.io/mt5ny ◽

2016 ◽

Author(s):

Arístide Márquez ◽

William James Senior ◽

Antonio Benítez ◽

Ivis Fermín ◽

Gregorio Martínez ◽

...

Keyword(s):

Organic Matter ◽

Chlorophyll A ◽

Significant Variation ◽

Significant Degree ◽

Ammonium Concentration ◽

Phytoplankton Production ◽

Density Anomaly ◽

Physical Chemical ◽

Decomposition Of Organic Matter ◽

Bottom Waters

The hydrochemical, physical-chemical, and biological dynamics were studied in the eastern waters of the gulf ofCariaco, where wind and precipitation patterns govern these processes to a significant degree. Average monthly values forboth surface and bottom waters were respectively as follows: temperature: 25.69 °C each; salinity: 35.41 and 35.75 units;density anomaly (ó-t): 23.43 and 23.84 kg/m3; oxygen concentration: 184.49 and 178.38 mmol/kg; pH: 7.98 and 7.94;nitrates: 3.18 and 4.22 μmol/L; nitrites: 0.45 and 0.60 μmol/L; ammonium: 1.25 and 1.39 μmol/L; total nitrogen: 25.28 and26.31 μmol/L. Phosphate concentrations between surface and bottom waters varied between 0.60 and 0.79 μmol/L, whereasthose of total phosphorus ranged from 2 to 170 μmol/L. Surface and bottom chlorophyll a concentrations ranged from 5.19to 4.33 mg/m3, respectively. ANOVA (P<0.05) did not reveal any significant variation between the values studied, but it didshow differences between the values for different months. Decomposition of organic matter was detected, as typified by bothoxygen utilization greater than 50 mmol/kg and denitrification (N*), which increased ammonium concentration and reducedthe pH during periods of upwelling relaxation. There was an imbalance between the maxima of chlorophyll a and those ofnutrients, which evidenced that phosphorus could be an inhibitor of phytoplankton production, especially during upwellingletup, when Readfield ratio increases from N:P = 16:1 up to N:P = 24:1.

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High local nutrient input influence on oligotrophic phytoplankton production and lipid biogeochemistry

10.5194/egusphere-egu21-15187 ◽

2021 ◽

Author(s):

Tihana Novak ◽

Blaženka Gašparović ◽

Ivna Vrana Špoljarić ◽

Milan Čanković

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Marine Phytoplankton ◽

Anthropogenic Sources ◽

Nutrient Concentrations ◽

Phytoplankton Production ◽

Nutrient Inputs ◽

Nutrient Input ◽

Organic Matter Production ◽

Matter Production

Marine phytoplankton are crucial for ecosystem function and responsible for almost half of world&#8217;s primary production. In order to grow and reproduce phytoplankton need sufficient amount of macro and micro nutrients. Nutrient concentrations are changeable in different water mases and dependable on different natural and anthropogenic sources such as terrestrial water inputs, recycling by sloppy feeding, remineralization with bacteria and atmospheric deposition. High nutrient input to oligotrophic regions raises phytoplankton biomass that leads to higher organic matter production and heterotrophs` development.&#160; Anthropogenic nutrient inputs are considered as the main cause of coastal eutrophication. Marine lipids, dominantly produced by phytoplankton, are good biogeochemical traces of organic matter origin and processing in marine environment and phytoplankton adaptation to environmental perturbations. They are important for multiple cell mechanisms functioning.The goal of this research was to investigate the influence of a point source of nutrients on organic matter production and lipid composition as a consequence of phytoplankton acclimation to different nutrient loads. We sampled at two geographically close stations in the Krka River Estuary mouth, oligo- to mesotrophic Martinska station and station in vicinity of the town of &#352;ibenik that is under high anthropogenic influence. Samples were taken from three depths (above, on and below halocline) and in four different seasons covering annual cycle. Lipid classes were characterized by thin&#8211;layer chromatography&#8211;flame ionization detection. Data are supported by hydrographic, dissolved organic carbon and particulate organic carbon parameters. We will discuss the changes of organic matter accumulation and estuarine lipid biogeochemistry caused by human activity.&#160;AcknowledgementThis research was financed by the Croatian Science Foundation project BiREADI (IP-2018-01-3105).

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Nearshore Dissolved and Particulate Organic Matter Dynamics in the Southwestern Baltic Sea: Environmental Drivers and Time Series Analysis (2010–2020)

Frontiers in Marine Science ◽

10.3389/fmars.2021.795028 ◽

2021 ◽

Vol 8 ◽

Author(s):

Helena Osterholz ◽

Christian Burmeister ◽

Susanne Busch ◽

Madleen Dierken ◽

Helena C. Frazão ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Baltic Sea ◽

Sea Water ◽

Environmental Drivers ◽

Nutrient Concentrations ◽

Phytoplankton Production ◽

Carbon And Nitrogen ◽

Nitrogen Concentrations ◽

Over Time

Dissolved and particulate organic carbon (DOC, POC) and nitrogen (DON, PON) constitute essential nutrient and energy sources to heterotrophic microbes in aquatic systems. Especially in the shallow coastal ocean, the concentrations are highly variable on short timescales, and cycling is heavily affected by different sources and environmental drivers. We analyzed surface water organic carbon and nitrogen concentrations determined weekly from 2010 to 2020 in the nearshore southwestern Baltic Sea (Heiligendamm, Germany) in relation to physical, chemical and biological parameters available since 1988. Mixing of low-DOC North Sea water with high-DOC Baltic Sea water, as well as in situ primary production, were confirmed as the main drivers of organic carbon and nitrogen concentrations. Tight coupling between POC, PON, chlorophyll a and phytoplankton carbon with DON seasonal dynamics corroborated the close relationship between phytoplankton production and degradation of organic nutrients with preferential remineralization of nitrogen. Significant changes in air and water temperature, salinity, and inorganic nutrients over time indicated effects of climate change and improved water quality management in the eutrophic Baltic Sea. Bulk organic nutrient concentrations did not change over time, while the salinity-corrected fraction of the DOC increased by about 0.6 μmol L–1yr–1. Concurrently, chlorophyll a and Bacillariophyceae and Cryptophyceae carbon increased, denoting a potential link to primary productivity. The high variability of the shallow system exacerbates the detection of trends, but our results emphasize the value of these extended samplings to understand coupled biogeochemical cycling of organic matter fractions and to detect trends in these important carbon reservoirs.

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Inter-annual variability on the water quality in the Lower São Francisco River (NE-Brazil)

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x3515 ◽

2016 ◽

Vol 28 (0) ◽

Cited By ~ 3

Author(s):

Paulo Ricardo Petter Medeiros ◽

Geórgenes Hilário Cavalcante ◽

Nilva Brandini ◽

Bastiaan Adriaan Knoppers

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

Inorganic Nitrogen ◽

Nutrient Concentrations ◽

Temperature Conductivity ◽

Dissolved Phosphorus ◽

Sao Francisco River ◽

Transversal Section ◽

São Francisco River ◽

Historical Series

Abstract: Aim This study characterized the water quality in the lower São Francisco River (NE-Brazil).This research represents the first work to be carried out in the lower sector of the São Francisco river aiming to quantify and compare limnological variables, during three different years (2001, 2004 and 2007). Methods Water samples were collected in a transversal section of the river at monthly intervals period on surface layer. Temperature, conductivity, pH, and dissolved oxygen were obtained using a multiparameter probe YSI-6600. The dissolved inorganic nutrients (ammonium, nitrite, nitrate, dissolved phosphorus and silicates), chlorophyll-a and total suspended sediment (TSS) were also determined. Results The three hydrological years showed differences in precipitation rates and discharge conditions. The year 2001 had precipitation rates below the historical series of rainfall. The mean annual water temperature showed negligible differences among the three years. Dissolved inorganic nutrient concentrations were highest in 2004, with ammonia and nitrate differing statistically between the years (p<0.05); the later showed the largest concentration of dissolved inorganic nitrogen. Chlorophyll-a showed a slight difference among years. Conclusions Precipitation intensity has a direct impact on the São Francisco River discharge, but the geographical distribution of the precipitation is also a determinant factor for alterations of the chemical and physical characteristics of the water that reaches the lower sector of the São Francisco River.

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Seagrass depth range and water quality in southern Moreton Bay, Queensland, Australia

Marine and Freshwater Research ◽

10.1071/mf9960763 ◽

1996 ◽

Vol 47 (6) ◽

pp. 763 ◽

Cited By ~ 95

Author(s):

EG Abal ◽

WC Dennison

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

Suspended Solids ◽

Light Attenuation ◽

River Mouth ◽

Total Suspended Solids ◽

Quality Parameters ◽

Depth Range ◽

Moreton Bay ◽

A Site

Correlations between water quality parameters and seagrass depth penetration were developed for use as a biological indicator of integrated light availability and long-term trends in water quality. A year-long water quality monitoring programme in Moreton Bay was coupled with a series of seagrass depth transects. A strong gradient between the western (landward) and eastern (seaward) portions of Moreton Bay was observed in both water quality and seagrass depth range. Higher concentrations of chlorophyll a, total suspended solids, dissolved and total nutrients, and light attenuation coefficients in the water column and correspondingly shallower depth limits of the seagrass Zostera capricorni were observed in the western portions of the bay. Relatively high correlation coefficient values (r2 > 0.8) were observed between light attenuation coefficient, total suspended solids, chlorophyll a, total Kjeldahl nitrogen and Zostera capricorni depth range. Low correlation coefficient values (r2 < 0.8) between seagrass depth range and dissolved inorganic nutrients were observed. Seagrasses had disappeared over a five-year period near the mouth of the Logan River, a turbid river with increased land use in its watershed. At a site 9 km from the river mouth, a significant decrease in seagrass depth range corresponded to higher light attenuation, chlorophyll a, total suspended solids and total nitrogen content relative to a site 21 km from the river mouth. Seagrass depth penetration thus appears to be a sensitive bio-indicator of some water quality parameters, with application for water quality management.

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Bulk, isotopic, petrographic organic matter and mineral distribution as proxies of environmental process in Guanabara Bay, SE, Brazil

Geo-Marine Letters ◽

10.1007/s00367-021-00698-4 ◽

2021 ◽

Vol 41 (3) ◽

Author(s):

R. C. Cordeiro ◽

D. D. dos Santos ◽

R. E. Santelli ◽

A. G. Figueiredo ◽

L. S. Moreira ◽

...

Keyword(s):

Organic Matter ◽

Guanabara Bay ◽

Mineral Distribution ◽

Se Brazil ◽

Environmental Process

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Linking patterns of freshwater discharge and sources of organic matter within the Río de la Plata estuary and adjacent marshes

Marine and Freshwater Research ◽

10.1071/mf16286 ◽

2017 ◽

Vol 68 (9) ◽

pp. 1704 ◽

Cited By ~ 5

Author(s):

Leandro Bergamino ◽

Mark Schuerch ◽

Adriana Tudurí ◽

Silvina Carretero ◽

Felipe García-Rodríguez

Keyword(s):

Organic Matter ◽

Surface Sediments ◽

Sediment Cores ◽

Freshwater Discharge ◽

C3 Plants ◽

Estuarine System ◽

Rio De La Plata ◽

Río De La Plata ◽

La Plata ◽

Matter Transport

We investigated carbon isotopic ratios (δ13C) v. carbon to nitrogen (C : N) ratios for surface sediments throughout a large estuarine system (Río de la Plata, RdlP), combined with sediment cores from adjacent marshes to infer main carbon sources. We also evaluated the influence of the El Niño–Southern Oscillation (ENSO) and associated high freshwater-discharge events on the organic-matter transport within the estuary. The isotopic pattern in surface sediments of the RdlP showed the upper reaches to be influenced by riverine particulate matter (δ13C range: –24 to –26‰). Similarly, in the sediment cores from marshes of the upper reaches, δ13C values decreased from –24‰ in ancient sediments to –28‰ in recent sediments, reflecting an increased contribution of organic matter from land, including C3 plants and freshwater phytoplankton, during the past 50 years. However, the lower reaches represent a depositional environment of marine algae (δ13C range: –21 to –23‰), with no influence of detritus from adjacent marshes, indicating minor erosion of the marshes in the lower reaches operating as carbon-sink habitats. Our isotopic analysis showed that the transport and deposition of terrigenous organic matter within the RdlP and adjacent marsh habitat appear to be both temporally and spatially linked to hydrology patterns.

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Nutrient distribution in the Bosphorus and surrounding areas

Water Science & Technology ◽

10.2166/wst.2002.0145 ◽

2002 ◽

Vol 46 (8) ◽

pp. 59-66 ◽

Cited By ~ 4

Author(s):

E. Okuş ◽

A. Aslan-Yilmaz ◽

A. Yüksek ◽

S. Taş ◽

V. Tüfekçi

Keyword(s):

Chlorophyll A ◽

Black Sea ◽

Nutrient Dynamics ◽

Lower Layer ◽

Water Quality Monitoring ◽

Nutrient Concentrations ◽

The Black Sea ◽

Sea Of Marmara ◽

Nutrient Distribution ◽

Northwestern Shelf

As part of a five years monitoring project “Water Quality Monitoring of the Strait of Istanbul”, February-December 1999 nutrient dynamics of the Black Sea-the Sea of Marmara transect are studied to evaluate the effect of discharges given by deep disposals. Through a one-year study, upper layer nutrient concentrations were generally under the effect of northwestern-shelf Black Sea originated waters. This effect was strictly observed in July, when the upper layer flow was the thickest. On the other hand, partly in November but especially in December the northwestern-shelf Black Sea originated water flow was a minimum resulting in similar concentrations in both layers. Nutrient fluctuations also affected the chlorophyll a and POC concentrations as parameters of productivity. The nutrient concentrations decreased with the effect of spring bloom and highest chlorophyll a values were detected in November at Strait stations that did not match to the Sea of Marmara values. This fact represents the time-scale difference between the Black Sea and the Sea of Marmara. On the contrary, high nutrient concentrations in the lower layer (especially inorganic phosphate), and therefore low N:P ratios reflect the effect of deep discharge. Vertical mixing caused by meteorological conditions of the shallow station (M3) under the effect of surface discharges resulted in homogenous distribution of nutrients. Nutrient concentrations of the stations affected by deep discharge showed that the two-layer stratification of the system did not permit the discharge mix to the upper layer.

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Studies on picophytoplankton in the southern Gulf of Mexico: recognition of picoprokaryotes and abundances of picophytoplankton during "dry season"

Brazilian Journal of Oceanography ◽

10.1590/s1679-87592013000400007 ◽

2013 ◽

Vol 61 (4) ◽

pp. 265-276 ◽

Cited By ~ 3

Author(s):

Aldo Aquino-Cruz ◽

David Uriel Hernández-Becerril ◽

Martha Signoret-Poillon ◽

David Alberto Salas-de-León ◽

María Adela Monreal-Gómez

Keyword(s):

Gulf Of Mexico ◽

Chlorophyll A ◽

River Mouth ◽

Dry Season ◽

Shallow Waters ◽

Southern Gulf Of Mexico ◽

Lower Maximum ◽

June July ◽

Abundance And Distribution ◽

Three Rivers

The abundance and distribution of total autotrophic picophytoplankton (PFP), temperature, salinity, PAR, and chlorophyll a were determined in two presumably contrasting environments: (1) two coastal areas (close to the mouths of three rivers), and (2) one oceanic area (Campeche Canyon), of the southern Gulf of Mexico, during the "dry season" (June-July, 2004). The picoprokaryotes Prochlorococcus and Synechococcus were identified by TEM, whereas Synechococcus and picoeukaryotes populations were also recognized by flow cytometry. The highest PFP abundance (1.67×105 cells ml-1) was found in shallow waters (~10 m depth) around the Grijalva-Usumacinta river mouth, followed by that found at a station close to the Coatzacoalcos River (1.19×105 cells ml-1); PFP abundances in the Campeche Canyon were usually lower (maximum 1.53×104 cells ml-1). Greater variability in PFP abundances was found in coastal stations than in oceanic waters, and weak relationships appeared between the patterns of chlorophyll a and PFP abundance. Peaks of PFP were detected in both coastal and more oceanic areas, but in the Campeche Canyon they were located deeper (60 m), relatively closer to the deep maximum of chlorophyll (located at about 75 m). Results suggest that PFP populations include a substantial photosynthetic component in both coastal and oceanic waters of the southern Gulf of Mexico.

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