Kay Hamer

Pb isotopes as a reliable marker of early mining and smelting in the Northern Harz province (Lower Saxony, Germany)

Overbank sediments from the River Weser provide a record of geochemical anomalies which vary distinctively from the regional background as far back as 3500 years BP. The use of Pb isotopes, measured by inductively coupled plasma mass spectrometry (ICP-MS), in combination with the determination of heavy metal concentrations has identified the mining and smelting activities that took place early in the Harz Mountains. as the source of contamination. The regional background was defined from sediments deposited prior to 3500 years BP with Pb and Zn concentrations of about 23^ 7 and 109^ 38 m gg 21 ; 206 Pb/ 207 Pb ratios of 1:215 ^ 0:002 and 208 Pb/ 206 Pb ratios of 2:044 ^ 0:002: The isotopic characteristics of the Pb in the sediments can be easily explained by a simple two-component mixing model involving: (i) the background component; and (ii) Pb derived from the Harz Mountain ore bodies characterised by 206 Pb/ 207 Pb ratios of 1.167‐1.187 and 208 Pb/ 206 Pb ratios of

Synthesis of the sednet work package 4 outcomes

1 Regione Emilia-Romagna, Responsabile servizio Tutela e Risanamento risorsa acqua, Via Dei Mille, Bologna, Italy 2 Technical University Hamburg-Harburg, Germany 3 Port of Rotterdam, Strategy and Communication Maritime Development, The Netherlands 4 Free and Hanseatic City of Hamburg, Dept. of Port and River Engineering, Germany 5 ICRAM, Italy 6 DEC NV, Belgium 7 ENEA, Italian Agency for new technologies and environment, Italy 8 AKWA Aquatic Sediment Expert Centre Ministry of Transport, Public Works and Water Management, The Netherlands 9 University of Bremen, Germany 10 ALTERRA Dept. of Water and the Environment, The Netherlands 11 Avd.leder, miljo Div. dir. environmental Engineering, Norway 12 ENVIS Srl, Via Fanin 48, 40127 Bologna, Italy 13 TNO, The Netherlands

pH and grain-size variation in leaching tests with bricks made of harbour sediments compared to commercial bricks

Bricks made of 50% wt. harbour sediments from Bremen, Germany, harbour sediment and nine commercial bricks made of common raw materials were leached in various experiments. The harbour sediment is polluted with heavy metals, e.g. Zn, Cd, Pb and organic compounds, e.g. tributyltin. To assess the environmental impact in the potential use of sediment bricks we consider the influence of pH (4-11) and grain size (50-30 000 microm), the two prime variables in the life-cycle of the bricks. Leachability of trace contaminants increased at acidic pH values and remained low at neutral and alkaline pH values. Leachability increased for smaller grain sizes in relation to the increasing specific surface areas. Grain sizes below 63 microm showed reverse effects for V, Cr, Ni, As, Sr, Mo and Pb due to sorption on the sample material or freshly precipitated phases such as barite, anhydrite or cuprous ferrite. A grain-size fraction of 125-1000 microm was selected in the leaching tests in order to compare different brick types. In general, the leachability of heavy metals from the sediment brick was in the upper range of the commercial bricks. At a temperature of 1050 degrees C thermal treatment of harbour sediments led to an immobilization of most trace contaminants. Chromium, V, As and Mo became even more mobile after thermal treatment, but the enhanced mobilization of V, As and Mo differed strongly among the bricks compared.

Overview on treatment and disposal options

Publisher Summary Economically and environmentally sound management and handling of dredged materials are important in Europe because huge amounts of dredged materials emerge from maintenance, construction (capital dredging), and remedial (cleanup) works within water systems. This chapter discusses different aspects of handling and treatment of dredged materials. In several European countries, treatment chains comprising one or more of the forenamed technologies are examined and compared. Disposal can be conducted in upland confined disposal sites or in subaquatic confined disposal sites. Former sand and gravel pits may also be used for subaquatic disposal. Both are best available technology/state-of-art (BAT) options. Large-scale sites are in operation in the Netherlands (subaquatic confined disposal sites) and in Germany (upland confined disposal sites). By using sand separation, soil is separated into a usable sand fraction and a contaminated silt fraction. The silt fraction is disposed or can be further processed, for example, by thermal immobilization.

Assessment of Treatment and Disposal Options

Summary Driven by science, engineering and daily practice in sediment management a big variety of technologies for treatment and disposal is available. Main fields for further development with respect to sediment management is to find the way to compare different complex scenarios of treatment and disposal (assessment) and to build up the markets for treatment of sediments. The SedNet mission makes obvious that sustainability is only achievable on a new spatial and time scale. Since the present structures for decision-making are mostly local or regional acting administrations, however their actions have often consequences on a bigger scale, the river basin scale. Additionally, to build up a sustainable sediment management long-termeffects over the time span of a generation or more have to be considered. According to the aim of a sustainable sediment management we recommend assessment on a river basin scale considering a sustainable time scale of one generation! A sustainable river basin model has to integrate social, environmental and economic aspects, but so far a model offering this is only vague: In a river basin the members of the society are the driving force, economy can be seen as the sum of activities and the environment is part of the “capital stock” that is available for development and activities of the society. Some parts of this “capital” is not renewable. Consequently, in a broader view of economy, neglecting environmental effects bears the risk of a loss of capital stocks, consequently decreasing the economy and social welfare on the long term. What are the consequences of this new river basin view? The people are the driving part in the system. In general, people can only react rationally with respect to economy and environment, if they are informed. Knowledge is the basis for understanding processes and mutual interaction and at least informed people will understand and accept rational decisions based on assessment procedures. Besides information of the public an assessment procedure is the second column for decision making. The outcome of such an assessment is a ranking of treatment alternatives offered for a sediment problem. Such an assessment should not base on a single tool e.g. a cost calculation or LCA, because no tool covers all fields necessary to be considered (economy, environment, society). It must be recommended that a combination of tools (Costs, LCA, cost-benefit evaluation, risk assessment studies) should become routine before decisionmaking. European standards for assessing treatment and disposal alternatives should consider the present know-how about long-term effects (e.g. the life-cycle of sediments and products and effects on mobility and bio-availability of pollutants with time) and the differences between the results of biological and chemical methods applied for the same sediments. Thinking about assessment standards leads to the necessity of harmonizing those standards Europewide in order to avoid transport of sediments across boarders between regions and countries in Europe applying different standards. Looking at sustainability some benefits like the reduction of space consumption, climate or re-use of secondary material substituting primary resources are complicated to be evaluated. We will come closer to sustainability the more we have an overall or comprehensive model considering economic factors as well as the environment. The example of the European Guideline for Trading Emission Certificates (2003/87/EC) can be seen as a general approach how to combine economy and ecology in a way accepted from the society. So we recommend to conduct research in fields that provide us with parameters or better tools to evaluate goods like “the landscape”, “space consumption”, etc. useful to improve decision making. Accordingly, an integration of broader economic know-how into the assessment procedures is needed in order to evaluate benefits outside common budgets on to consider “hidden costs” and superior issues like source control or resource demands, which are not covered by the responsibility and budget of water and sediment management authorities today.

Regional Distribution Patterns of Heavy Metals in Sediments Dredged from a Harbour Basin

Within the framework of a regional research programme in a harbour basin of Bremen, the regional distribution patterns of heavy metals, grain size fractions, Al, organic matter and Eh values were investigated. Due to regular distribution of nearly all the above parameters, it was possible to create maps of the patterns. The overall heterogeneous harbour sludge showed homogeneous areas in a scale of hundreds of metres. Additionally, the heavy metal contents of different grain size fractions were analysed in order to find out whether there are grain size fractions that can be used without further treatment. Heavy metal concentrations and their relation to standards, natural processes controlling heavy metal distribution patterns and aspects of practical relevance are discussed.

Geochemisches Langzeitverhalten und Schwermetallmobilität von Baggergut

Zur Erhaltung der Schiffahrtstiefen mussen in den Hafen der Stadt Bremen pro Jahr ca. 700 000 m3 Sedimente (Schutenaufinas) gebaggert werden. Dieses Baggergut ist mit Schwermetallen belastet und wird zur Zeit deponiert. Da Deponieflachen knapp und teuer sind, wird nach weiteren Moglichkeiten des Umgangs gesucht. Eine Alternative bzw. Erganzung zur Deponierung von Baggergut stellt die Verwertung als mineralisches Dichtungmaterial fur Oberflachenabdichtungen von Deponien dar.

Verwertung von Baggergut zur Ziegelherstellung

Jahrlich fallen in Deutschland 10 bis 15 Mio m3 Baggergut zur Erhaltung der Schiffbarkeit von Wasserstrasen und Hafen an. Vor dem Hintergrund von 700 000 m3 schadstoffbelastetem Hafenschlick aus seinen Hafenbecken sucht das Bundesland Bremen nach Verwertungswegen fur das Baggergut, die Alternativen zur bereits praktizierten Deponierung des Materials darstellen. Aufgrund seiner Korngrosenverteilung und seiner mineralogischen Zusammensetzung eignet sich Baggergut zur Ziegelherstellung.

Das Transportverhalten von Cadmium und Kupfer in Grundwasserleitersanden unter Berücksichtigung von Karbonatgleichgewichten

Bekanntermasen hat die Belastung der Umwelt durch Cadmium und Kupfer, die hier exemplarisch aus der Gruppe der Schwermetalle untersucht wurden, als Folge anthropogener Aktivitaten in den letzten Jahrzehnten stark zugenommen. Die Gefahrdungsabschatzung und Sanierung von Verschmutzungen des Boden- und Grundwasserbereiches erfordert eine umfangreiche Kenntnis der mobilitatsbestimmenden Prozesse im Grundwasserleiter. In der vorliegenden Arbeit wurde der Schwermetalltransport im Spezialfall einer Calcitlosungszone in sandigem Untergrund (z.B. Ohse 1983) mit Hilfe von Saulenversuchen untersucht. Saulenversuche bieten die Moglichkeit, die Mobilitat der Schwermetalle unter eng definierten Randbedingungen im Labor betrachten und interpretieren zu konnen. Desweiteren konnten die experimentell erhaltenen Parameter mit einer Modellierung der Transportprozesse mit dem Programm CoTAM verglichen werden (Hamer u. Sieger 1994).

Methoden zur Parameterermittlung für die Simulation geochemischer Prozesse beim Schadstofftransport im Grundwasser

Bei der Modellierung des Schadstofftransportes im Grundwasser sind neben hydrodynamischen Vorgangen der Advektion und Dispersion geochemische Wechselwirkungen zwischen den im Wasser gelosten Stoffen und der Festphase des Grundwasserleiters zu berucksichtigen. Dabei sind vor allem Prozesse wie Sorption/Desorption, Losung/Fallung, Reduktion/Oxidation und Vorgange beim Umsatz organischer Substanz von Bedeutung. Zur modellmasigen Beschreibung der Einzelprozesse und ihrer Berucksichtigung im Transportmodell mussen zunachst Parameter definiert werden, die das Verhalten kennzeichnen. Diese Parameter konnen beispielsweise in standardisierten Laborversuchen ermittelt werden. In der Regel werden zur Beschreibung geochemischer Reaktionen wie etwa Sorptionsvorgangen Schuttelversuche in geschlossenen Systemen durchgefuhrt, in denen stoffspezifische Parameter definiert werden. Bei der Betrachtung von Sorptionsprozessen anorganischer Schadstoffe spielen neben Austauschvorgangen spezifische Sorptionsvorgange vor allem an Hydroxiden eine wichtige Rolle, die langsam ablaufen. In Schuttelversuchen bestimmte kinetische Parameter lassen sich jedoch nicht auf Fliessysteme ubertragen. Am Beispiel von Blei, Kupfer und Arsenat werden im folgenden standardisierte Versuchsaufbauten vorgestellt, die offene Systeme darstellen und das Stromungsfeld im Grundwasserleiter simulieren.