Geochemistry of dissolved trace metals (cadmium, copper, zinc) in the Scheldt estuary, southwestern Netherlands: Impact of seasonal variability

Zwolsman, J.J.G.; Eck, Bert T. M. Van; Weijden, C. H. Van der

doi:10.1016/s0016-7037(97)00029-x

Cited by 149 publications

(112 citation statements)

References 72 publications

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“…For veri®cation purposes, data sets were used from October and November 1978 (Duinker et al, 1983;Nolting et al, 1999b), 1987(Zwolsman and Van Eck, 1993Zwolsman et al, 1997) and 1991±1995 (Paucot, 1997;Paucot and Wollast, 1997).…”

Section: Methodsmentioning

confidence: 99%

“…Anoxia may occur through a combination of high organic matter content and a long residence time. This may be restricted to the sediment (Westerlund et al, 1986;Kerner and Wallmann, 1992;Zwolsman, 1999) but can also occur in the water column (Zwolsman et al, 1997;Shiller and Mao, 1999). Such anoxic conditions may induce the precipitation of sulphides of Zn and Cd.…”

Section: Introductionmentioning

confidence: 99%

“…For Zn, conclusions from the literature are less unambiguous, but¯occulation, precipitation as sulphides and adsorption on particles are processes of its chemistry in the upper low-salinity estuary. Often, but not always, a release of Zn into the water phase is observed upon oxidation (Duinker et al, 1983;Zwolsman et al, 1997;Paucot and Wollast, 1997). Then, also Zn concentrations demonstrate a mid-estuarine maximum (Duinker et al, 1983) and its chemistry, as for Cd, can be explained by complexation with inorganic anions from seawater (Kraepiel et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…However, organic complexation of Zn plays an important role in Zn release in estuaries ( Van den Berg et al, 1987). Sometimes no estuarine maximum for Zn is observed at all (Zwolsman et al, 1997;Baeyens et al, 1998a,b).…”

Section: Introductionmentioning

confidence: 99%

“…Since the early 1980s, the extension of the anoxic zone has been decreasing due to improving water quality of the river Scheldt (Van Damme et al, 1995;Van Eck et al, 1998;Zwolsman, 1999). In the1970s, the anoxic zone reached to where S 15±20; whereas since the mid-1980s oxidation normally occurs at S 2±10: Only under extreme conditions (high temperatures and low river discharge) does anoxia reach further downstream towards higher salinities (Zwolsman et al, 1997). In the anoxic region the pH ranges between 7 and 8, or even higher, mainly due to nitri®cation (Frankignoulle et al, 1996;Zwolsman et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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The influence of salinity on the solubility of Zn and Cd sulphides in the Scheldt estuary

Gerringa

Baar

Nolting

et al. 2001

Journal of Sea Research

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In the estuary of the river Scheldt, where an oxygen gradient exists in addition to the salinity gradient, redox processes will be of major importance for trace metal mobilisation. In this study, the in¯uence of salinity and pH on the redox processes of dissolved Zn and Cd sulphides is investigated together with the effects on the ratio of the dissolved Zn and Cd concentrations. The speciation of these metals is calculated with the chemical equilibrium programme mineql 1 . Zn sulphides are oxidised at lower oxygen concentrations than Cd sulphides, due to lower stability constants, causing a sudden increase or peak in the dissolved Zn/Cd ratio. The formation of dissolved Cd chloride complexes when oxidation occurs at high salinities S 15 increases the mobility of Cd, causing a decrease in the Zn/Cd peak of the total dissolved concentrations. The peak is three to four times smaller at S 15 than when oxidation occurs at S 2: The simple model calculations compare very well with ®eld data. The Scheldt estuary is suitable to illustrate these calculations. In the 1970s, the anoxic part of the estuary reached S 15±20; but since the early 1980s it has dropped to S 2±10: Historic data on metals in the estuary from 1978, 1987 and the 1990s were used to compare with the equilibrium calculations. The increase of the dissolved Zn/Cd peak at low salinity as a consequence, of the decreasing anoxic region is con®rmed well by the data. The good agreement between model calculations and ®eld data is a proof of the extreme importance of redox processes for the solubility of Zn and Cd sulphides in the estuary. q

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The influence of salinity on the solubility of Zn and Cd sulphides in the Scheldt estuary

Gerringa

Baar

Nolting

et al. 2001

Journal of Sea Research

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Anthropophile elements in river sediments: Overview from the Seine River, France

Chen

Gaillardet

Bouchez

et al. 2014

Geochem Geophys Geosyst

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In contrast to larger river systems that drain relatively pristine basins, little is known about the sediment geochemistry of rivers impacted by intense human activities. In this paper, we present a systematic investigation of the anthropogenic overprints on element geochemistry in sediments of the humanimpacted Seine River, France. Most elements are fractionated by grain size, as shown by the comparison between suspended particulate matter (SPM) and riverbank deposits (RBD). The RBD are particularly coarse and enriched in carbonates and heavy minerals and thus in elements such as Ba, Ca, Cr, Hf, Mg, Na, REEs, Sr, Ti, Th, and Zr. Although the enrichment/depletion pattern of some elements (e.g., K, REEs, and Zr) can largely be explained by a binary mixture between two sources, other elements such as Ag, Bi, Cr, Cd, Co, Cu, Fe, Mo, Ni, Pb, Sb, Sn, W, and Zn in SPM in Paris show that a third end-member having anthropogenic characteristics is needed to account for their enrichment at low water stage. These ''anthropophile'' elements, with high enrichment factors (EFs) relative to the upper continental crust (UCC), display a progressive enrichment downstream and different geochemical behaviors with respect to the hydrodynamic conditions (e.g., grain size) compared to elements having mainly a natural origin. Our findings emphasize the need for systematic studies of these anthropophile elements in other human-impacted rivers using geochemical normalization techniques, and stress the importance of studying the chemical variability associated with hydrodynamic conditions when characterizing riverine element geochemistry and assessing their flux to the ocean.

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Autoxidation as a major player in the fate of terrestrial particulate organic matter in seawater

et al. 2017

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The Rhône River plays a major role in the Mediterranean Sea, being both its main freshwater source and its major particulate matter provider. This survey of the fate of terrestrial particulate organic matter (POM) was conducted along the salinity gradient of the Rhône River plume, between 2012 and 2014. It revealed that autoxidation acts rapidly and intensely upon the POM's arrival at sea, with α‐amyrin and β‐amyrin autoxidation rates going from 12.9 ± 2.9% to 45.0 ± 6.4% and 10.7 ± 4.0% to 50.3 ± 4.4%, respectively, between fresh water (salinity 0) and seawater (salinity 38). These compounds, being unambiguous markers of the terrestrial origin of POM, allow us to unequivocally characterize the POM as terrestrial. While it was originally believed that a desorption of redox‐active trace metal ions was the favoring factor that kick‐started this intense autoxidation, this study evidences no trace metal desorption in the Rhône River mixing zone and hence no correlation between high autoxidation rates and the presence of trace metal ions. Autoxidation rates however were very well correlated with salinity levels within the river plume, with r2 reaching 0.801, 0.962, and 0.943 for sitosterol, α‐amyrin, and β‐amyrin, respectively, in November 2014.

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Geochemistry of dissolved trace metals (cadmium, copper, zinc) in the Scheldt estuary, southwestern Netherlands: Impact of seasonal variability

Cited by 149 publications

References 72 publications

The influence of salinity on the solubility of Zn and Cd sulphides in the Scheldt estuary

The influence of salinity on the solubility of Zn and Cd sulphides in the Scheldt estuary

Anthropophile elements in river sediments: Overview from the Seine River, France

Autoxidation as a major player in the fate of terrestrial particulate organic matter in seawater

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