An experimental study on the mixing behavior of Ti, Zr, V and Mo in the Elbe, Rhine and Weser estuaries

Schneider, Alexandre B.; Koschinsky, Andrea; Kiprotich, Joseph; Poehle, Sandra; Nascimento, Paulo Cı́cero do

doi:10.1016/j.ecss.2015.12.002

Cited by 17 publications

(12 citation statements)

References 45 publications

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“…Although the coastal seawater sample is appropriate for the Honokohau Harbor mixing experiment, it may not be representative of coastal seawater from Kiholo Bay, and hence, for the Lava tube mixing experiment. For each mixing experiment aliquots of groundwater from the Honokohau Harbor well or the Hind well were mixed in various proportions with the seawater sample to achieve a series of samples with salinities ranging from ≤ 2 to ~ 36.7; we refer to this mixing path as endpoint mixing (e.g., Hoyle et al, 1984;Garnier and Guieu, 2003;Schneider et al, 2016). We recognize that serial dilution is an alternative model that could also simulate mixing processes in subterranean estuaries.…”

Section: Subterranean Estuary Mixing Experimentsmentioning

confidence: 99%

Rare earth element behavior during groundwater–seawater mixing along the Kona Coast of Hawaii

Johannesson

Palmore

Fackrell

et al. 2017

Geochimica et Cosmochimica Acta

101

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Groundwater and seawater samples were collected from nearshore wells and offshore along the Kona Coast of the Big Island of Hawaii to investigate rare earth element (REE) behavior in local subterranean estuaries. Previous investigations showed that submarine groundwater discharge (SGD) is the predominant flux of terrestrial waters to the coastal ocean along the arid Kona Coast of Hawaii. Groundwater and seawater samples were filtered through 0.45 μm and 0.02 μm pore-size filters to evaluate the importance of colloidal and soluble (i.e., truly dissolved ionic species and/or low molecular weight [LMW] colloids) fractions of the REEs in the local subterranean estuaries. Mixing experiments using groundwater collected immediately down gradient from a wastewater treatment facility (WWTF) proximal to the Kaloko-Hanokohau National Historic Park, and more "pristine" groundwater from a well constructed in a lava tube at Kiholo Bay, were mixed with local seawater to study the effect of solution composition (i.e., pH, salinity) on the concentrations and fractionation behavior of the REEs as groundwater mixes with seawater in Kona Coast subterranean estuaries. The mixed waters were also filtered through 0.45 or 0.02 μm filters to ascertain the behavior of colloidal and soluble fractions of the REEs across the salinity gradient in each mixing experiment. Concentrations of the REEs were statistically identical (two-tailed Student ttest, 95% confidence) between the sequentially filtered sample aliquots, indicating that the REEs occur as dissolved ionic species and/or LMW colloids in Kona Coast groundwaters. The mixing experiments revealed that the REEs are released to solution from suspended particles or colloids when Kona Coast groundwater waters mix with local seawater. The order of release that accompanies increasing pH and salinity follows

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Section: Subterranean Estuary Mixing Experimentsmentioning

confidence: 99%

Rare earth element behavior during groundwater–seawater mixing along the Kona Coast of Hawaii

Johannesson

Palmore

Fackrell

et al. 2017

Geochimica et Cosmochimica Acta

101

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“…Fe concentrations of field samples from the mixing zone were in the same range and showed similar dynamics as observed in the MIX NF experiment. Strong variation (''sawtooth" patterns) in Fe concentration during mixing are described in the literature and have also been observed during mixing experiments with river water and seawater for Ti and Zr (Schneider et al, 2016). Such behavior may be related to the dynamics of particles or surface phenomena and has also been linked to differential behavior of distinct Fe pools, as colloidal and dissolved Fe (Aucour et al, 2003;Gaillardet et al, 2014;Mulholland et al, 2015).…”

Section: General Trends During Mixingmentioning

confidence: 76%

Riverine mixing at the molecular scale – An ultrahigh-resolution mass spectrometry study on dissolved organic matter and selected metals in the Amazon confluence zone (Manaus, Brazil)

Simon¹,

Osterholz²,

Koschinsky

et al. 2019

Organic Geochemistry

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The Amazon delivers a fifth of the global continental runoff and riverine dissolved organic carbon (DOC) to the ocean. Intensified biogeochemical processes are expected at the junction of the Amazon's major blackwater tributary, the Rio Negro, and its parent, the Rio Solimões, due to large gradients in pH, conductivity, DOC and particle load. Dissolved organic matter (DOM) plays a major role in aquatic biogeochemical processes which are poorly understood on the molecular level. To gain insights into the potential role of DOM in non-conservative processes, we assessed dynamics of Cu, Fe and DOM by ultrahigh resolution mass spectrometry in: (1) endmembers, (2) regional samples and (3) laboratory mixing experiments under presence/absence of natural particles (>0.2 lm). The relative abundances of 3600 DOM molecular formulae were interpreted via multivariate statistics which revealed major dynamics in the DOM molecular composition. >40% of molecular formulae displayed conservative behavior even in the presence of natural particles, agreeing with bulk DOC behavior, but opposing the oftenpresumed non-conservative behavior of DOM. Another 16-27% of formulae fluctuated in FT-ICRMS signal intensity during mixing, but did not show consistent non-conservative behavior. Both rivers left a clear molecular imprint within the DOM of the Amazon, each being linked to >800 molecular formulae. Characteristic for the Rio Negro was a dominance of phenolics with a wide molecular mass range (centered at $400 Da), and for the Rio Solimões more saturated but lower-molecular mass compounds (centered at $300 Da). Both Fe and Cu showed distinct non-conservative mixing patterns under particle presence. In the controlled mixing experiments including original particles at natural concentration, up to 0.5 lg/L Cu was released from the particles into solution at 20-40% blackwater contribution. Our molecular analysis revealed distinct DOM compositional changes in polyphenol-and nitrogencontaining formulae paralleling this release, suggesting links to desorption of potential ligands and charge-induced effects at particle surfaces caused by pH and conductivity changes in the course of mixing.

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“…Cu-HS substances [54]) may also participate to the metal flux to 106 organisms and methods based on anodic stripping voltammetry can estimate this 107 bioavailable fraction [19;55]. 108 published in Current Opinion 3 (2017) [144][145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161][162] CSV in presence of relatively high concentration of added ligand(s) is also widely used 109 as a detection technique and is very helpful in gaining insights into the cycling of 110 various metals, such as that of Zr, Mo, V and Ti at increasing salinities [56]. Although 111 the Hg drop electrode is still used for developments of new CSV methods (e.g.…”

Section: List Of Nomenclature and Abbreviationsmentioning

confidence: 99%

A review on electrochemical methods for trace metal speciation in environmental media

Companys

Galceran

Pinheiro

et al. 2017

Current Opinion in Electrochemistry

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11Trace metal speciation is key to understand/predict bioavailability and potential toxicity 12 of metals to biota and will, undoubtedly, be incorporated in future regulations. 13Electroanalytical methods have a role to play in such development: they offer a wide 14 range of advantages such as speed, portability, economy, solid interpretation 15 backgrounds and low limits of quantification. This review focusses on three selected 16 stripping techniques: Competitive-Ligand Exchange -Cathodic Stripping Voltammetry 17 (CLE-CSV), Scanned Stripping Chrono-Potentiometry (SSCP) and AGNES (Absence 18 of Gradients and Nernstian Equilibrium Stripping) reporting their working principles, 19 characteristics (strong and weak points) and recent applications to systems of 20 environmental relevance (such as seawaters, freshwaters or soil extracts). 21 22 23 24 Keywords: speciation, availability, electroanalysis, electrochemistry, heavy metal, 25 CLE-CSV, SSCP, AGNES 26 27 published in Current Opinion 3 (2017) 144-162 33 Speciation (i.e. the distribution of an element among its different chemical forms[1]) 34 has been recognised as a key factor for trace metal (bio)availability to biota, as 35 postulated by hegemonic ecotoxicological paradigms such as the Free Ion Activity 36 Model (FIAM) [2] or the Biotic Ligand Model (BLM)[3], both assuming that the free 37 ion is the only bioavailable species. The limits of these models have recently been 38 reviewed [4], highlighting numerous cases where specific fractions of metal complexes 39 can be internalized, either directly or through the dissociation of labile complexes. Thus, 40there is a need to design, develop, apply and interpret analytical techniques able to 41 provide reliable speciation information [5][6][7] that can be used by regulatory bodies. 42Although there are numerous non-electrochemical techniques [5][6][7][8][9][10][11][12][13], those that are 43 provide attractive possibilities such as speed of analysis, low-cost and miniaturization in 44 view to on-site (and in-situ) measurements [14], and can also provide thermodynamic 45 (i.e. equilibrium) information (such as the amount of the free metal, the amount of 46 complexing sites, the stoichiometry of complexes and their stability constants [15]) as 47 [16;17]. Stripping techniques, due to their low detection limits, are well suited for 50 environmental analysis. They are two-stage techniques, where the first stage is a 51 deposition step that accumulates the analyte (at the electrode surface or in its volume), 52 followed by a second stage that quantifies this analyte. Anodic Stripping Voltammetry 53 (ASV), in its multiple variants, is the most popular and has the advantage to possibly be 54 measuring a potentially bioavailable fraction of the metal, as shown again recently 55 [18;19]. 56 57 published in Current Opinion 3 (2017) 144-162 This critical evaluation focusses on three techniques that are known powerful tools for 58 metal speciation: AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) 59 and SSCP...

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An experimental study on the mixing behavior of Ti, Zr, V and Mo in the Elbe, Rhine and Weser estuaries

Cited by 17 publications

References 45 publications

Rare earth element behavior during groundwater–seawater mixing along the Kona Coast of Hawaii

Rare earth element behavior during groundwater–seawater mixing along the Kona Coast of Hawaii

Riverine mixing at the molecular scale – An ultrahigh-resolution mass spectrometry study on dissolved organic matter and selected metals in the Amazon confluence zone (Manaus, Brazil)

A review on electrochemical methods for trace metal speciation in environmental media

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