Wim Salomons

Sediments and the Transport of Metals

Sediments are important carriers for trace metals in the hydrological cycle, an aspect which will be discussed in chapters dealing with individual parts of the hydro-logical cycle. However, sediment research has certain aspects of its own, which warrants a separate discussion. Therefore, we will discuss those aspects of metals and sediments which are common to all parts of the hydrological cycle.

Trace elements and carbon and nitrogen stable isotopes in organisms from a tropical coastal lagoon

Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (δ13C and δ15N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by 15N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between δ15N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption.

Mobility of Heavy Metals in Dredged Harbor Sediments

Solubility, mobility, and bioavailability of sediment-bound metals can be increased by four major factors: (1) Lowering of pH; (2) changing of redox conditions; (3) formation of organic complexes; and (4) increasing salinity. While the first two factors are particularly important for on-land deposition of dredged materials, the effect of salinity is particularly important for resuspended cadmium-rich sediments in estuaries. Chemical extraction studies, which were carried out under carefully controlled conditions on both fresh and freeze-dried samples, indicate that aeration of anoxic sediments (e.g., on-land disposal) may both increase and decrease the mobility of heavy metals. Transformation from sulfidic or carbonatic associations to oxidic phases will reduce mobility of manganese, wherease the respective changes from moderately reducible forms to carbonatic and easily reducible phases will enhance the reactivity of zinc during oxidation of dredged material.

Nitrogen Source Apportionment for the Catchment, Estuary, and Adjacent Coastal Waters of the River Scheldt

Using the systems approach framework (SAF), a coupled model suite was developed for simulating land-use decision making in response to nutrient abatement costs and water and nutrient fluxes in the hydrological network of the Scheldt River, and nutrient fluxes in the estuary and adjacent coastal sea. The purpose was to assess the efficiency of different long- term water quality improvement measures in current and future climate and societal settings, targeting nitrogen (N) load reduction. The spatial-dynamic model suite consists of two dynamically linked modules: PCRaster is used for the drainage network and is combined with ExtendSim modules for farming decision making and estuarine N dispersal. Model predictions of annual mean flow and total N concentrations compared well with data available for river and estuary (r² ≥ 0.83). Source apportionment was carried out to societal sectors and administrative regions; both households and agriculture are the major sources of N, with the regions of Flanders and Wallonia contributing most. Load reductions by different measures implemented in the model were comparable (~75% remaining after 30 yr), but costs differed greatly. Increasing domestic sewage connectivity was more effective, at comparatively low cost (47% remaining). The two climate scenarios did not lead to major differences in load compared with the business-as-usual scenario (~88% remaining). Thus, this spatially explicit model of water flow and N fluxes in the Scheldt catchment can be used to compare different long-term policy options for N load reduction to river, estuary, and receiving sea in terms of their effectiveness, cost, and optimal location of implementation.

Introduction: The Need for Risk-Informed River Basin Management

As the pressures from both anthropogenic and natural causes on environmental systems increase, it is no longer effective or efficient to deal with one issue at a time, since solving a singular problem often causes damaging impacts on other environmental compartments or in other places. We must consider the consequences of our actions on all parts of the environment in an integrated way and configure these actions to cope with an uncertain future. These challenges demand a different approach in order to achieve actual improvement of the ecological quality of our river basins and thus sustain the goods and services they provide for the well-being of society. Risk-informed management is this new approach. It involves the integrated application of three key principles: be well informed, manage adaptively and take a participatory approach. This chapter introduces this risk-informed management approach as it was developed in the European Commission funded project RISKBASE and provides an introduction to rest of this book where the key principles are explained and underpinned in detail.

Group report: Integrated assessment and future scenarios for the coast

A prototype scenario assessment was carried out with help of a DP-S-I-R framework to provide an outline forward look at the European coastal areas. Impacts of change were assessed for the following major sectoral or cross-sectoral drivers: climate change, agriculture/forestry, urbanisation, tourism, industry and trade, fishery and shellfish fishery, and energy. The present situation was tabulated prior to an outline of the impacts of three scenarios, i.e. (1) a world market perspective, (2) global sustainability and (3) environmental stewardship. From twelve identified impact categories, three were judged to be of particular significance in the present situation: habitat loss (including coastal squeeze); changes in biodiversity; and the loss of fisheries productivity. A group of three impacts – eutrophicationrelated effects, contamination-related effects and coastal erosion – were all judged to be of moderate importance in most areas. All others were allocated only local importance. The analysis suggests that the major current drivers will still play the dominant role, augmented by climate change. Drivers and impacts intensities usually increase under the perspective of a more globalised world (scenario 1) and usually decrease through better management, mitigation and adaptation measures of scenarios 2 and 3. Under scenario 1, the eastern countries (Black Sea and Baltic Sea areas) are particularly prone to eutrophication and contamination impacts, as well as habitat and biodiversity loss, due to expansion of mass tourism eastwards, together with intensification of agriculture and aquaculture. Under scenario 2 more stringent regulations and management reduce environmental impacts. Under scenario 3 impacts are reduced through decentralisation, although this may also result in sub-optimal management (local fragmentation).

ELOISE research and the implementation of EU policy in the coastal zone

This paper presents a timely review of European coastal research as brought together in the ELOISE programme, at the end of its third phase of funding. The programme is intended to be the response of the EC to the challenge highlighted by the Land-Ocean Interactions in the Coastal Zone research project (LOICZ). Following a review of policy issues in the European coastal zones, and EU initiatives to address them, we assess the actual and potential contributions of research project findings to ELOISE objectives, and to the implementation of EU policy legislation affecting the coast. We identify several discrepancies between the project outputs of the ELOISE programme and the information needs arising from the implementation of the relevant directives. We suggest underlying causes for these discrepancies, and propose new research priorities to mitigate the information gap problem.

Metals in Estuaries and Coastal Environments

Like lakes, estuaries are ephemeral in respect to geologic time. They must be regarded as dynamically evolving land-forms that go through a life cycle from valley creation, followed by the drowning phase, and ending up with the progressive backfilling with sediments (Fairbridge, 1980). The origin of most modern estuaries dates back to the rise of the sea level after the last Ice Age. The history of an estuarine system after it has been established as a geomorphological entity is largely determined by its sediment supply (Postma, 1967). Mass particulate balance is controlled by the input to the estuary from rivers, the atmosphere and sea, as well as by the output of substances to the ocean and to the bottom (Goldberg, 1978). Accumulation of sediment — even of fine-grained material — can take place due to protection from wave action and currents. Net shore-ward transport of suspended matter is influenced by waves, tidal movement and a typical estuarine circulation, the latter being caused by differences in specific gravity between river and sea water.

Metals in the Ocean

The oceans are the last part of the hydrological cycle and here trace metals are removed from the hydrological cycle and incorporated in the sediments. There they spend several hundred million of years before taking part in the next hydrological cycle.

Downscaling Scenarios as an Exploratory Tool for River Basin Management: An Introduction

Global change in river basins can be anticipated by using downscaled scenarios. This approach is introduced in this chapter, and it is argued that scenarios are a well-developed and suitable tool to explore the uncertain bandwidth of the future states of river basins, their rivers and occupant societies. Quantitative and qualitative scenario exercises are introduced and a worked-out example is presented for the Scheldt river basin.