Effect of organic complexation on the behaviour of dissolved Cd, Cu and Zn in the Scheldt estuary

Baeyens, Willy; Goeyens, Léo; Monteny, F.; Elskens, Marc

doi:10.1007/978-94-017-3573-5_5

Cited by 18 publications

(24 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(2) 3% of the dissolved Zn (including the ionic fraction), and 50 and 93% of the dissolved Cd is inorganic at S 2 and 15, respectively. The distribution over the dissolved species of Zn is heavily in¯uenced by organic ligands; for Cd this in¯uence is minor at higher salinities and of moderate importance at low salinity in agreement with the conclusions of Van den Berg et al (1987) and Baeyens et al (1998c), and others. Van den Berg et al (1987), one of the ®rst to point out the importance of organic complexation for metals in solution, concentrated their investigation on the middle and lower estuary, while they had only two data points at 9 , S , 15: Their low salinity data suggest a Zn/ ligand ratio .1.…”

Section: Comparison With ®Eld Data From the Scheldt Estuarysupporting

confidence: 90%

“…of metal, respectively. Using the maximum K 0 values of Baeyens et al (1998c) we obtain a maximum a 0 of 50.4 for Zn and 0.8 for Cd. The values for a inorg are 0.62 for Zn and 1.8 S 2 and 9.3 S 15 for Cd.…”

Section: Comparison With ®Eld Data From the Scheldt Estuarymentioning

confidence: 92%

“…In reality, the inorganic species do not have such high concentrations as calculated (Fig. 1) Baeyens et al (1998c) used Kd values (concentration in the particulate phase divided by the concentration in the dissolved phase) and concentrations of dissolved labile metals in a model to calculate the conditional stability constants of metal±organic complexes. They found almost similar K 0 values for Zn and Cd, ranging from 10 7 to 10 9.1 for Zn, in agreement with the results of Van den Berg et al (1987), and from 10 6.9 to 10 8.9 for Cd.…”

Section: Comparison With ®Eld Data From the Scheldt Estuarymentioning

confidence: 99%

“…Van den Berg et al (1987), one of the ®rst to point out the importance of organic complexation for metals in solution, concentrated their investigation on the middle and lower estuary, while they had only two data points at 9 , S , 15: Their low salinity data suggest a Zn/ ligand ratio .1. The model of Baeyens et al (1998c) produces at low salinities, S , 12:5; ligand concentrations (the sum of two ligand groups) which for Zn are lower than the dissolved Zn concentrations. For Cd, the sum of the concentrations of the two ligand groups remains larger than the metal concentrations, even at S 1 and 3.5.…”

Section: Comparison With ®Eld Data From the Scheldt Estuarymentioning

confidence: 99%

“…With increasing salinity, Cd is released by the combination of the formation of dissolved chloride complexes and by competition with Ca for adsorption sites on suspended particles (Paalman et al, 1994). Organic complexation in the dissolved phase occurs, but to a lesser extent than for metals like Zn and Cu (Kozelka and Bruland, 1998;Baeyens et al, 1998c). 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.…”

Section: Introductionmentioning

confidence: 99%

See 4 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

View full text Add to dashboard Cite

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

show abstract

Section: Comparison With ®Eld Data From the Scheldt Estuarysupporting

confidence: 90%

Section: Comparison With ®Eld Data From the Scheldt Estuarymentioning

confidence: 92%

Section: Comparison With ®Eld Data From the Scheldt Estuarymentioning

confidence: 99%

Section: Comparison With ®Eld Data From the Scheldt Estuarymentioning

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

View full text Add to dashboard Cite

show abstract

Combined effects of lowered oxygen and toxicants (copper and diazinon) on the mayfly Ephoron virgo

Geest

Soppe

Greve

et al. 2002

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

In many large European rivers, the number of typical riverine insect species, such as mayflies, stoneflies, and caddisflies, is greatly reduced compared to historic records. This can no longer be explained by high concentrations of a relatively small number of dominant toxicants since many rivers have changed from heavily contaminated systems with a few selected key toxicants to systems with a complex contamination. This contamination consists of many substances in low concentrations coinciding with other unfavorable conditions, such as low oxygen concentrations. It was hypothesized that the joint adverse effects of such multiple stressors may be a steering factor in the distribution of riverine insect species. The aim of this study was therefore to determine the combined effects of toxicants and oxygen depletion. To this purpose, larvae of the indigenous riverine mayfly Ephoron virgo were exposed to two different model toxicants, copper and diazinon, under normoxia and hypoxia (50% air saturation) conditions. The median effective concentrations for mortality for copper were significantly lower in the hypoxia treatments than in the normoxia treatments. For diazinon, no differences were observed between two treatments differing in dissolved oxygen levels, and therefore we argue that interactions between multiple stressors may be compound specific. It is concluded that the combination of toxicants and lowered oxygen may have a stronger impact than can be expected based on the adverse effects of the individual factors and that standard toxicity tests may be insufficient alone to determine the impact of human activities on the ecological state of riverine communities. Instead, attention needs to be paid to more environmentally realistic nonoptimal conditions in toxicity testing to adequately fulfill the needs of ecological recovery programs.

show abstract

Effects of organic matter, alkalinity and pH on acute copper toxicity to mosquitofish,Gambusia holbrooki: Implications for a multipurpose management of irrigation ponds

Sáez

Casas

Guil-Gerrero

et al. 2013

Internat. Rev. Hydrobiol.

View full text Add to dashboard Cite

This study evaluates the effects of water quality, i.e. organic matter content, alkalinity, and pH, on acute copper toxicity to mosquitofish (Gambusia holbrooki Girard, 1859), an invasive species widespread in natural and artificial wetlands. The aim of this study was to improve our understanding of the consequences of CuSO4 treatments on biodiversity conservation in irrigation ponds. Tests were carried out using three water types: irrigation‐pond water (IPW) of relatively high organic matter levels and slightly alkaline pH; IPW treated with sodium hypoclorite (IPW + SH) to remove organic matter and raise pH; dechlorinated tap water (DTW) with a relatively low alkalinity and organic matter, and a circumneutral pH. Fish were exposed for 96‐h under static conditions to 0.25, 0.75, 1.5, and 4 mgCu/L. Mortality was monitored every 24 h and LC50 values were determined. After the 96 h period, the Cu concentration in gills was also determined. The LC50‐96 h values were 1.90 (IPW), 1.51 (IPW + SH), and 0.78 (DTW) mg Cu/L, which can be considered relatively high. The concentration of copper in gills increased with the nominal Cu concentration in the three water treatments, and was significantly higher in DTW compared with IPW and IPW + SH. These results indicate that the relatively high alkalinity and, particularly, organic matter levels in pond water substantially buffer copper bioavailability to mosquitofish. However, chronic exposure to continuous Cu treatments and its accumulation in pond sediments are likely to produce stress symptoms at the individual and population levels of vertebrate and invertebrate species, which, besides agronomical and human health reasons, advise against using CuSO4 as a management tool for irrigation ponds.

show abstract

Effect of organic complexation on the behaviour of dissolved Cd, Cu and Zn in the Scheldt estuary

Cited by 18 publications

References 15 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

Combined effects of lowered oxygen and toxicants (copper and diazinon) on the mayfly Ephoron virgo

Effects of organic matter, alkalinity and pH on acute copper toxicity to mosquitofish,Gambusia holbrooki: Implications for a multipurpose management of irrigation ponds

Contact Info

Product

Resources

About