A box-model of metal flows through the Scheldt estuary (1981–1983 and 1992–1995)

Baeyens, Willy; Monteny, F.; Ryssen, Ramses Van; Leermakers, Martine

doi:10.1007/978-94-017-3573-5_7

Cited by 8 publications

(17 citation statements)

References 11 publications

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“…The input respectively output average annual water flow amounts to 104 m 3 s )1 respectively 148 m 3 s )1 with a relative standard deviation of about 30%. Similar calculations are presented in Baeyens et al (1998a). In the dissolved phase, the riverine (input) flux of Ni, Pb and Zn is about 2-3 times higher than the output flux to the marine system.…”

Section: Seasonal Patternssupporting

confidence: 58%

“…All in-and outgoing flows have been put together in a box-model, and a mass balance for each box has been calculated. Only in 5 boxes on 30, the imbalance was larger than 20%, with a highest value of 29% (Baeyens et al, 1998a). For all particulate metals, sedimentation appears to be a very important process, reducing strongly the output into the sea.…”

Section: Introductionmentioning

confidence: 97%

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Overview of trace metal contamination in the Scheldt estuary and effect of regulatory measures

et al. 2005

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Seasonally, dissolved and particulate metal concentrations in the Scheldt estuary were assessed over a period of 4 years (1995)(1996)(1997)(1998). High quality data were obtained following stringent analytical protocols for each step: sampling, sample treatment, sample storage and analysis. Of the 5 trace metals, Ni showed the most conservative behaviour, while Cd and Cu were clearly transferred from the particulate to the dissolved phase in the middle estuary. A substantial part of the particulate metals entering the estuarine system are lost through sedimentation. General seasonal patterns are the following: lower concentrations in spring and higher ones in winter (sometimes late fall/early winter) for dissolved metals, while in summer a pronounced rise of the longitudinal concentration profile is observed for the particulate metals. A comparison of the trace metal concentrations (dissolved and particulate) at the mouth of the estuary in 1995-1998 with those from 1981 to 1983, reveal reductions between 30 and 58%. Reductions based on direct emission measurements for almost the same period suggest reductions (dissolved + particulate) between 42 and 64%. Biomagnification (BMF) is the accumulation of a compound through the foodchain. It is in our case expressed as the ratio of the metal concentration in the organism (lg g )1 , d.w.)/the metal concentration in total suspended matter (lg g )1 , d.w.). Almost all BMF-values of Periwinkle, Nereis diversicolor and Macoma balthica (3 bottom organisms in the Scheldt estuary) are negative meaning that these organisms contain less heavy metals than the particulate suspended matter. For all organisms log BMFs for Pb, respectively Ni, are around )1.8, respectively )0.7. For Cd, Periwinkle shows slight enrichment (0.05) and for Cu even more (0.45), while negative values were observed for Nereis diversicolour and Macoma balthica. The latter organisms are more enriched in Zn ()0.09) than Periwinkle ()0.43).

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Section: Seasonal Patternssupporting

confidence: 58%

Section: Introductionmentioning

confidence: 97%

Overview of trace metal contamination in the Scheldt estuary and effect of regulatory measures

et al. 2005

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“…Moreover, USES-LCA does not take differences between seawater and fresh water uptake capacity into account. In particularly, the inclusion of ionic strength effects on the adsorption of dissociating organic substances and metals will improve the current model structure (Johnson and Westhall, 1990;Bayens et al, 1998).…”

Section: -     mentioning

confidence: 99%

Uncertainty and variability in environmental life-cycle assessment

Huijbregts

2002

Int J LCA

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General introductionIncreased rates of resource depletion, land use, solid waste generation and emissions of pollutants became issues of broad public concern in the beginning of the seventies (Meadows et al., 1972). Unfortunately, most of these problems are still with us today, and some of them have increased substantially (World Resources Institute, 1996). One way to decrease the environmental pressure of human activities is the environmentally improvement of production processes (Reijnders, 1996). In this respect, an important question to be answered is 'how exactly can we measure the environmentally improvement of production processes?' Environmental life-cycle assessment (LCA) aims to answer that question. The first section of this chapter provides an overview of the LCA framework. Although the framework itself is well-established, the application of the framework is in many aspects problematic. A brief overview of the problems associated with the actual implementation of the framework is described in second paragraph. Finally, the aim and the structure of the present thesis is outlined in the third paragraph. § 1.1 Environmental life cycle assessment Environmental life cycle assessment (LCA) is a tool for the assessment of the environmental impact of product systems (Heijungs et al. 1992). It considers the full life cycle of a product from resource extraction to waste disposal. LCA is generally divided into four phases: goal and scope definition, inventory analysis, impact assessment, and interpretation (Figure 1.1; ISO, 1997a).In the goal and scope definition, the aim and the subject of an LCA study are determined and a 'functional unit' is defined. An example of a functional unit is 'the consumption of 100 kg apples' with, for instance, the aim to compare the environmental impacts of different agricultural production processes of apples. In the inventory analysis, for each of the product systems considered data are gathered for all the relevant processes involved in the life cycle. A product system can be considered as a combination of processes needed for the functioning of a product or service. The outcome of the inventory analysis is a list of all extractions of resources and emissions of substances caused by the functional unit for every product system considered, generally disregarding place and time of the extractions and releases. The matrix method can be used to perform the inventory analysis (Heijungs, 1996(Heijungs, , 1997 where i is the vector of environmental interventions, H is the environmental intervention matrix, representing the extractions of resources and emissions of substances per unit process, G is the technology matrix representing the inter-process flows needed for the functioning of the product system, and u is the external supply vector, related to the functional unit. Life cycle impact assessment (LCIA) aims to improve the understanding of the inventory result. Firstly, it is determined which extractions and emissions contribute to which impact categories. An impact category can...

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“…pended matter flux at the riverine/estuarine interface (Rupelmonde) at 320 10 (Baeyens et al, 1998), the sediment mass balance estimates for the downstream part of the estuary have been updated and refined (Figure 8). Nevertheless, these values are to be considered as orders of magnitude.…”

Section: Suspended Matter Fluxes Through the Estuarymentioning

confidence: 99%

“…Concentrations of dissolved Pb, Hg, Zn, Cu and Cd in the coastal estuarine water mass are about 2 times higher than in the marine water mass of the Belgian coastal zone, which is a part of the Southern Bight of the North Sea (Baeyens et al, 1987), and an order of magnitude higher than ocean values. In the Scheldt estuary itself, the heavy metal concentrations are still significantly higher than in the coastal estuarine water mass (Baeyens et al, 1998: see related paper on 'Sea inputs'). Therefore, a better understanding of the respective biogeochemical cycles of heavy metals in the Scheldt estuary with emphasis on the basic governing processes is essential.…”

Section: Introductionmentioning

confidence: 99%

General description of the Scheldt estuary

Baeyens¹,

Eck²,

Lambert

et al. 1998

Trace Metals in the Westerschelde Estuary: A Case-Study of a Polluted, Partially Anoxic Estuary

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A general description of the Scheldt estuary, including the hydrology, the sediment transport, the productivity and the biodegradation with respect to their influence on the trace metal behaviour in the Scheldt estuary, is given.The river basin can be divided in several sections according to their morphological, hydrodynamical and sedimentary properties. The zone from km 78 to 55, which corresponds roughly with the salinity zone from 2 to 10 psu, is the zone of high turbidity, high sedimentation and of oxygen depletion, especially in the summer period. That area is called the geochemical filter because the solid/dissolved distribution of the trace metals is controlled by redox, adsorption/desorption, complexation and precipitation/coprecipitation processes. The sedimentation rate in that area is estimated at 280 Mkg y ,1 .In the downstream estuary the phytoplankton activity increases due to the restoration of oxygen and to the much lower turbidity values. That area is called the biological filter because incorporation of trace metals by the plankton communities lowers the trace metal concentrations during the productivity period, while transformation of metal species, especially observed with mercury, occurs during that period too.

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A box-model of metal flows through the Scheldt estuary (1981–1983 and 1992–1995)

Cited by 8 publications

References 11 publications

Overview of trace metal contamination in the Scheldt estuary and effect of regulatory measures

Overview of trace metal contamination in the Scheldt estuary and effect of regulatory measures

Uncertainty and variability in environmental life-cycle assessment

General description of the Scheldt estuary

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