Rhenium distribution and behaviour in the salinity gradient of a highly stratified estuary

2021 ◽  
Author(s):  
Elvira Bura-Nakić ◽  
Lucija Knežević ◽  
Jelena Mandić ◽  
Ana-Marija Cindrić ◽  
Dario Omanović
Keyword(s):  
River Discharge ◽  
Salinity Gradient ◽  
Planetary Science ◽  
Salinity Range ◽  
Winter Period ◽  
Icp Ms ◽  
Indian River ◽  
Geochemical Behaviour ◽  
Stratified Estuary ◽  
Conservative Behaviour

<p>In oxic waters, Re<sup>VII </sup>is the stable oxidation state which undergo hydrolysis to the relatively unreactive perrhenate ion, Re<sup>VII</sup>O<sub>4</sub><sup>- [1]</sup>. The oceanic dissolved Re exhibits quite conservative behaviour with the concentration of about 40 pM <sup>[2]</sup>. Despite the frequent utilization of Re for the atmosphere and the ocean past redox state reconstructions, the geochemical behaviour of Re in the modern surface environments such as rivers, estuaries as well as in seawater is not well studied. Understudy is partially arising from the fact that Re has low seawater and riverine concentration of 4 pM and 16.5 pM, respectively<sup></sup><sup>[1, 3]</sup>. In the Amazon and the Hudson estuaries, in crease of Re concentration at low and middle salinity regions is observed<sup> [4]</sup>. On the other hand, Re exhibits complete conservative behaviour in Indian river estuaries, i.e. Narmada, Tapi and the Mandovi estuaries in the Arabian Sea and the Hooghly estuary in the Bay of Bengal <sup>[5]</sup>. Deviation from conservative behaviour in Re can be explained as the interplay of variety of factors including the nature and composition of the particles, Eh-pH conditions, biological productivity and fate of the organic matter. <sup>[5]</sup>.</p><p>Here we present the Re concentration profiles in the freshwater part of the karstic Krka river (Croatia) and its 23 km long estuarine segment, covering a full salinity range (0.1 to 38.6). Analysis of Re was performed by its preconcentration and separation using an anion exchange resin (Dowex 1X8) followed with the ICP-MS quantification using isotope dilution (ID) method. The Krka River spring is characterised by the low Re concentration (~6 pM). A noticeable anthropogenic influence at the point of the wastewater discharge of the Knin town was observed (27 pM). This input probably caused a progressive downstream increase of Re concentration to 12 pM at the freshwater end-member in the winter period (with a high Krka River discharge) and 17 pM in the summer period (low Krka River discharge). In the estuarine segment, a near-conservative behaviour of Re was found, with the "oceanic" concentration of 38 pM in the seawater end-member.</p><p> </p><p>References:</p><p>[1] Hasse AA et al., (2019) Coordination chemistry reviews 394: 135-161.</p><p>[2] Anbar AD et al., (1992) Geochimica et Cosmochimica Acta<strong> </strong>56:4099-4103.</p><p>[3] Miller CA et al., (2011) Geochimica et Cosmochimica Acta 75:7146-7179.</p><p>[4] Colodner D et al., (1993) Earth and Planetary Science Letters 117:205-221.</p><p>[5] Rahaman W and Singh SK (2010) Marine Chemistry 118: 1-10.</p>

scholarly journals Analysis Methods for Characterizing Salinity Variability from Multivariate Time Series Applied to the Apalachicola Bay Estuary

2012 ◽  
Vol 29 (4) ◽  
pp. 613-628 ◽  
Author(s):  
Steven L. Morey ◽  
Dmitry S. Dukhovskoy
Keyword(s):  
Time Series ◽  
Time Scales ◽  
River Discharge ◽  
River Flow ◽  
High Salinity ◽  
Multivariate Time Series ◽  
Salinity Range ◽  
Apalachicola Bay ◽  
Analysis Methods ◽  
Salinity Variability

Abstract Statistical analysis methods are developed to quantify the impacts of multiple forcing variables on the hydrographic variability within an estuary instrumented with an enduring observational system. The methods are applied to characterize the salinity variability within Apalachicola Bay, a shallow multiple-inlet estuary along the northeastern Gulf of Mexico coast. The 13-yr multivariate time series collected by the National Estuary Research Reserve at three locations within the bay are analyzed to determine how the estuary responds to variations in external forcing mechanisms, such as freshwater discharge, precipitation, tides, and local winds at multiple time scales. The analysis methods are used to characterize the estuarine variability under differing flow regimes of the Apalachicola River, a managed waterway, with particular focus on extreme events and scales of variability that are critical to local ecosystems. Multivariate statistical models are applied that describe the salinity response to winds from multiple directions, river flow, and precipitation at daily, weekly, and monthly time scales to understand the response of the estuary under different climate regimes. Results show that the salinity is particularly sensitive to river discharge and wind magnitude and direction, with local precipitation being largely unimportant. Applying statistical analyses with conditional sampling quantifies how the likelihoods of high-salinity and long-duration high-salinity events, conditions of critical importance to estuarine organisms, change given the state of the river flow. Intraday salinity range is shown to be negatively correlated with the salinity, and correlated with river discharge rate.

scholarly journals Implications of Nutrient Enrichment and Related Environmental Impacts in the Pearl River Estuary, China: Characterizing the Seasonal Influence of Riverine Input

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3245
Author(s):  
Lixia Niu ◽  
Pieter van Gelder ◽  
Xiangxin Luo ◽  
Huayang Cai ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Nutrient Enrichment ◽  
River Discharge ◽  
Nutrient Dynamics ◽  
Southern China ◽  
Salinity Gradient ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
The Pearl River Estuary ◽  
The Pearl River

The Pearl River estuary is an ecologically dynamic region located in southern China that experiences strong gradients in its biogeochemical properties. This study examined the seasonality of nutrient dynamics, identified related environmental responses, and evaluated how river discharge regulated nutrient sink and source. The field investigation showed significant differences of dissolved nutrients with seasons and three zones of the estuary regarding the estuarine characteristics. Spatially, nutrients exhibited a clear decreasing trend along the salinity gradient; temporally, their levels were obviously higher in summer than other seasons. The aquatic environment was overall eutrophic, as a result of increased fluxes of nitrogen and silicate. This estuary was thus highly sensitive to nutrient enrichment and related pollution of eutrophication. River discharge, oceanic current, and atmospheric deposition distinctly influenced the nutrient status. These factors accordingly may influence phytoplankton that are of importance in coastal ecosystems. Phytoplankton (in terms of chlorophyll) was potentially phosphate limited, which then more frequently resulted in nutrient pollution and blooms. Additionally, the nutrient sources were implied according to the cause–effect chains between nutrients, hydrology, and chlorophyll, identified by the PCA-generated quantification. Nitrogen was constrained by marine-riverine waters and their mutual increase-decline trend, and a new source was supplemented along the transport from river to sea, while a different source of terrestrial emission from coastal cities contributed to phosphate greatly.

scholarly journals DYNAMICS OF A LONGITUDINALLY STRATIFIED ESTUARY

1976 ◽  
Vol 1 (15) ◽  
pp. 177 ◽  
Author(s):  
Jorg Imberger
Keyword(s):  
Density Gradient ◽  
Fresh Water ◽  
Salinity Gradient ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
First Order ◽  
Vertical Density ◽  
Stratified Estuary ◽  
Set Up ◽  
Australian Estuary

Introduction. A partially stratified estuary is defined as one which possesses a quite definite longitudinal salinity gradient from the mouth to the head of the estuary, but only a very weak vertical or transverse salinity structure. For an estuary to exhibit such characteristics it must possess a source of fresh water near the head of the estuary, sufficient vertical mixing to overcome the potential energy associated with such a fresh water inflow and be very much longer than its width to reduce transverse variations. If the estuary is very shallow (a few meters) then wind generated turbulence is often sufficient to eliminate most or all the vertical structure. Deeper, or very sheltered, estuaries require additional strong tidal shears to break up the vertical density gradients. However, in both cases the mixing is usually not sufficient to completely homogenize the estuary longitudinally and it is found that these estuaries display a near linear salinity gradient along the principle axis of the estuary throughout most of the spring and summer months. Such a density gradient drives a gravitational circulation within the estuary which leads to a net transport of salt from the sea mouth to the head of the estuary. Two dimensional theories (see for instance Rat tray and Mitsuda (1974)) have been established, but In general these greatly underestimate the longitudinal transport found in such estuaries and three dimensional circulation effects must be considered. Fischer (1972) was the first to recognise this fact and he carried out a first order analysis which pointed to a greatly increased longitudinal dispersion. However, Fischer (1972) carried out his analysis only to first order, not explaining how the transverse pressure field, set up by the first order velocity field convecting the longitudinal density gradient, is balanced. It is the purpose of this paper to give a rigorous foundation to Fischer's (1972) hypothesis that it is the transverse variations in velocity which yield the greatest contribution to any longitudinal transport of the density or any passive pollutant. Furthermore, the presented theory is applied to a local Western Australian estuary which is ideally suited for such a comparison complying strictly to the assumptions of the theory.

scholarly journals Simulating the Delaware Bay Buoyant Outflow: Comparison with Observations

2006 ◽  
Vol 36 (1) ◽  
pp. 3-21 ◽  
Author(s):  
Michael M. Whitney ◽  
Richard W. Garvine
Keyword(s):  
River Discharge ◽  
Vertical Structure ◽  
Numerical Models ◽  
Salinity Gradient ◽  
Model Performance ◽  
Field Research ◽  
Delaware Bay ◽  
Coastal Current ◽  
Surface Drifter ◽  
Estuarine Salinity

Abstract Coastal buoyant outflows from rivers and estuaries previously have been studied with field research, laboratory experiments, and numerical models. There is a dire need to evaluate model performance in light of coastal current observations. This research simulates the Delaware Bay outflow and compares results with observations of estuarine and shelf conditions. Observations include an estuarine salinity climatology, a record of freshwater delivery to the shelf, coastal current salinity mappings, and surface drifter data. Simulation efforts focus on spring 1993 and spring 1994, the primary field study period. The simulation is forced with river discharge, winds, and tides; only tidal-averaged results are discussed. Estuarine salinity results are consistent with the observed lateral salinity pattern, vertical structure, and response to river discharge. Salinities within the lower bay agree with observations, but the simulation overestimates the along-estuary salinity gradient. Observed and simulated freshwater delivery exhibit the same amplitude of response to river discharge and winds. The simulation produces a buoyant outflow that is generally consistent with the observed buoyancy signature, width, length, and vertical structure over a variety of river discharge and wind conditions. The simulated coastal current, however, tends to be somewhat shorter and fresher than observed. Simulated surface drifter paths exhibit the observed onshore advection during downwelling winds as well as offshore transport and current reversals during upwelling winds. A statistical evaluation based on shelf salinity mappings indicates that the model reproduces the observed variance and has only a small bias (less than 10% of plume buoyancy signature). The rms error of 1.2 psu is linked to the shorter and fresher nature of the simulated coastal current. Observational comparisons discussed in this paper indicate that the model can simulate many coastal current features and its response to river discharge and wind forcing.

A Unified Method of Estimating Longitudinal Dispersion in Estuaries

1989 ◽  
Vol 21 (8-9) ◽  
pp. 981-993 ◽  
Author(s):  
J. K. Park ◽  
A. James
Keyword(s):  
Water Quality ◽  
Dispersion Coefficient ◽  
Salinity Gradient ◽  
Longitudinal Dispersion ◽  
Quality Model ◽  
Advective Flux ◽  
Salinity Data ◽  
Stratified Estuary ◽  
Dispersive Flux ◽  
Unified Method

A procedure was developed to estimate the rate of longitudinal dispersion from the observed data and verified by applying it to both the narrow, partially-stratified estuary and the wide, well-mixed estuary. It was found that the dispersive flux is not proportional to the longitudinal salinity gradient (dS/dx) in estuaries and is most closely related to velocity, the advective flux and (dS/dx)2 rather than dS/dx. The results obtained from the procedure showed that negative longitudinal dispersion can occur especially in flood tide. It was investigated whether the dispersion coefficient estimated from observed salinity data can be applied to the prediction of a water quality, such as dissolved oxygen, BOD, ammonia or temperature. The observed dispersion coefficients were successfully applied in a water quality model.

scholarly journals EXPERIMENTAL RESEARCH FOR TECHNOLOGICAL PREPARATION OF ARTEMIA (ARTEMIA) ARTIFICIAL CULTIVATION IN SALT LAKES

2020 ◽  
Vol 2 (338) ◽  
pp. 69-73
Author(s):  
A. V. Ubaskin ◽  
K. I. Akhmetov ◽  
A. I. Lunkov ◽  
N. T. Yerzhanov ◽  
T. Zh. Abylkhassanov ◽  
...  
Keyword(s):  
Saline Water ◽  
Salinity Range ◽  
Winter Period ◽  
Optimal Salinity ◽  
Technological Preparation ◽  
Standard Solution ◽  
Artemia Cysts ◽  
Hatching Rates ◽  
Artificial Cultivation

An integral part of the technological preparation of artificial cultivation of brine shrimp in saline water is a set of preliminary experimental work to assess the quality of cysts. It has been shown that during the winter period, activation of Artemia cysts occurs from the initial hatching values of 5-10 % to 72-99 %. The most optimal salinity range for hatching nauplii is a salinity of 20-30 g/l. With an increase in salinity above these indicators, hatching decreases. The size of hatching of Artemia depends on the salinity of a natural reservoir. In reservoirs with salinity of 50-80 g / l, higher hatching rates were obtained than with salinity of 150-160 g/l. Higher hatching rates are observed when using natural lake water for incubation. During incubation of cysts in a standard solution and fixed salinity and temperature conditions, the development rate of various stages of nauplii from the beginning of the opening of cysts (breaking stage) and pre-nauplius to active nauplii is shown. After 1.5–2 h after the mass appearance of pre-nauplii, they completely change into the nauplius stage.

scholarly journals Insignificant enhancement of export flux in the highly productive Subtropical Front, east of New Zealand: a high resolution study of particle export fluxes based on <sup>234</sup>Th:<sup>238</sup>U disequilibria

2011 ◽  
Vol 8 (5) ◽  
pp. 9535-9576
Author(s):  
K. Zhou ◽  
S. D. Nodder ◽  
M. Dai ◽  
J. A. Hall
Keyword(s):  
New Zealand ◽  
Salinity Gradient ◽  
Salinity Range ◽  
Water Type ◽  
Export Flux ◽  
Low Salinity ◽  
Iron Fertilization ◽  
Natural Iron ◽  
Poc Export ◽  
Particle Export

Abstract. We evaluated the downward Particulate Organic Carbon (POC) export fluxes in the Subtropical Frontal zone (STF) of the Southern Ocean. The site is characterized by enhanced primary productivity which has been suggested to be stimulated through so-called natural iron fertilization processes at its northern boundary where iron-depleted subantarctic water (SAW) mixes with oligotrophic, iron-replete subtropical water (STW). We adopted the small-volume 234Th method to achieve highest spatial sampling resolution as possible based on a cruise to the STF to the east New Zealand in austral late autumn-early winter, May–June 2008. The inventories of fluorescence, particulate 234Th and POC observed in the upper 100 m were all elevated in the mid-salinity part of the water type (34.5<S<34.8), compared with low (S<34.5) and high (S>34.8) salinity waters. However, Steady-State 234Th fluxes were similar cross all of the salinity gradient being 1484 in the mid-salinity, and 1761 and 1304 dpm m−2 d−1 in the high and low salinity zones respectively. Bottle POC/Th ratios at the depth of 100 m were used to convert the Th fluxes into POC export flux. The POC flux was again not enhanced in the mid-salinity range where the primary production was highest, being 7.4 mmol C m−2 d−1 as compared to 9.9 mmol C m−2 d−1 in high salinity waters, and 5.9 mmol C m−2 d−1 in low salinity waters. This study implied that natural iron fertilization does not necessarily lead to the enhancement of POC export in STF regions.

scholarly journals Rhenium distribution and behaviour in the salinity gradient of a highly stratified estuary and pristine riverine waters

2021 ◽  
Author(s):  
Elvira bura-Nakić ◽  
Lucija Knežević ◽  
Jelena Mandić ◽  
Ana-Marija Cindrić ◽  
Dario Omanović
Keyword(s):  
Inductively Coupled Plasma ◽  
Salinity Gradient ◽  
Strong Increase ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Concentration Step ◽  
Stratified Estuary ◽  
Small Positive Deviation ◽  
A Minor ◽  
Abundance And Distribution

Abstract The abundance and distribution of dissolved Re (DRe) has been determined in the freshwater part of the Krka River (Croatia), draining the karstic carbonate landscape, as well as in the salinity gradient of its highly stratified estuary. Due to low DRe concentration, the batch procedure consisting of pre-concentration step using an anion exchange resin (Dovex) and analysis of DRe in 8 M HNO 3 eluate using a high resolution inductively coupled plasma mass spectrometry (HR ICP-MS) was adopted. Due to the potential inconsistent recoveries, ranging from 60% to 87%, the quantification was performed by using the isotope dilution (ID) technique. The DRe concentration in the Krka River basically increased in the downstream direction, with the 6.2 pM at the spring site, reaching 11.9 pM before the estuarine region. The weathering of the surrounding carbonate lithology is assumed as the source of natural Re. The two specific anomalies were registered: a strong increase in DRe concentration due to the anthropogenic input near the town of Knin (27.5 pM) and a decrease at downstream site caused by the subterranean input of freshwater of the Zrmanja River leading to relatively low DRe concentration (8.5 pM). In the estuarine segment, a near-conservative behavior of DRe was found in the salinity gradient of the upper surface layer, with the DRe concentration ranging from 18 to 38 pM. An anthropogenic supply was suggested within the estuarine segment close to the urban area causing a small positive deviation from the conservative line. In the bottom seawater layer, a minor decrease of DRe concentration in the most upstream estuarine regions was evidenced, implying a potential weak scavenging of Re.

scholarly journals Studies of dissolved carbohydrates (or carbohydrate-like substances) in an estuarine environment

2016 ◽  
Author(s):  
William James Senior ◽  
Lionel Chevolot
Keyword(s):  
Organic Matter ◽  
Biological Activity ◽  
Salinity Gradient ◽  
Early Spring ◽  
Estuarine Environment ◽  
Bay Of Brest ◽  
Conservative Behaviour

Variations in concentrations of dissolved sugars were studied along the salinity gradient of a smallestuary (Elorn, Bay of Brest, France) from February 1985 to January 1986. Total dissolved carbohydrate(TDCHO) and dissolved monosaccharides (MCHO) were measured by the methods of Burneyand Sieburth and Johnson and Sieburth respectively. It must be noted that these methods cannotdistinguish between carbohydrates and carbohydrate-like substances; consequently, these methodsprobably do not closely reflect biologically available pools of carbohydrates. In the river, TDCHO andMCHO values ranged from 230 to 970 /ig C 1"' and from 75 to 450 ngC\-^ respectively. In theestuary, TDCHO and MCHO were usually lower; they varied respectively from 20 to 570 /zg C 1~'and from 0 to 180/ig C1 '. In June, some TDCHO values were much higher, probably because somepolysaccharide was produced at this time by phytoplankton excretion or lysis.The relationship between Cl%o and TDCHO was dependent on the seasons. TDCHO was conservativein autumn, winter and early spring. TDCHO and DOC concentrations were fairly well correlatedduring the same period. Similar results have been previously reported by various workers. MCHOand TDCHO concentrations were well correlated throughout this study except in June. From theseresults, it was concluded that most dissolved carbohydrates were linked to a conservative fraction ofthe organic matter in periods of low biological activity, whereas newly biosynthesised carbohydrateswere responsible for non-conservative behaviour.

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