Michael Steiger

Distribution and Fate of Heavy Metals in the North Sea

In recent years coastal and shelf systems such as the North Sea have attracted considerable attention where heavy metal studies are concerned. There has been growing concern over the last decade regarding the effects of industrial discharges on heavy metal levels in nearshore waters and ecosystems, which has been documented in the reports of the first and second International North Sea Conference. As a result of the high input of pollutants from both the British Isles and the European continent, and a limited dilution on account of the shallow waters, the southern North Sea has often been regarded as the most heavily polluted marine area in the world since the early seventies (Weichart 1973). Metal pollution assessments from sediment analysis (e.g., Groot et al. 1971; Banat et al. 1972; Gadow and Schafer 1973) formed a background of these early discussions.

Weathering and Deterioration

It is generally assumed that stone is one of the most durable materials because it is compared to weaker building materials, such as wood or mud. But stone can deteriorate and many factors will affect it. The nature of the stone is critical in determining its resistance to the various deterioration factors. The most important one, salt, was already identified by Herodotus, nearly two and a half millennia ago. However, salt by itself is not damaging, it requires the presence of water for its aggressiveness to become evident. And water is needed for biocolonization to occur, for freeze-thaw phenomena and for wet-dry expansion. Control of this single factor can decrease significantly the deterioration potential of a stone and any structure built from it. The chapter aims to present a review of the most important deterioration processes and their effect on the various types of stones and rocks used by man. Among them are thermal effects, the influence of moisture, both as water vapor or in liquid state, the presence of salts and the damages that can be expected from biocolonization. The chapter also aims at identifying the areas where more research is needed to understand the actual deterioration mechanism of the various factors.

In situ Raman observation of the crystallization in NaNO3–Na2SO4–H2O solution droplets

Several double salts have been detected in building materials and most of these salts are incongruently soluble compounds. In contrast to single salts, however, no systematic investigations of the crystallization behavior and deleterious effects of incongruently soluble double salts exist. To assess the damage potential of these salts, a systematic investigation of their highly complex behavior is desirable. This paper deals with the crystallization behavior of various solids in the ternary mixed NaNO3–Na2SO4 system including the formation of the double salt darapskite, Na3NO3SO4·H2O. The crystallization sequence during droplet evaporation experiments at room conditions was determined using Raman and polarization microscopy. The basic idea of this research is to use deviations of the crystallization sequence of a salt or a mixed salt solution from the equilibrium pathway as an indicator to detect the degree of supersaturation. The observed crystallization pathway includes the formation of the metastable phases Na2SO4(III), Na2SO4(V) and darapskite. The experimental observations are discussed on the basis of the NaNO3–Na2SO4–H2O phase diagram and the results provide evidence for crystal growth from highly supersaturated solutions in both systems. If the crystals growing under these conditions are confined, these supersaturations result in substantial crystallization pressures.

The origin of lead in urban aerosols — a lead isotopic ratio study

Inductively coupled plasma mass spectrometry (ICP-MS) has been used to investigate the lead isotopic composition of selected sources for particulate emissions. Besides emission source samples, lead isotopic ratios in samples of airborne particulate matter have been determined. Multiple linear regression has been used to correlate the lead isotope ratios with tracer elements for waste incineration and copper smelting of airborne particulate matter samples.

The mode of formation of thecotrichite, a widespread calcium acetate chloride nitrate efflorescence

Abstract The widespread occurrence of thecotrichite, Ca3(CH3COO)3Cl(NO3)2·7H2O, in the museum environment is explained theoretically by construction and examination of its phase diagram. Thecotrichite formation was simulated in the laboratory to identify the key factors involved in its production. This efflorescence occurs on porous limestone or calcareous artefacts such as pottery, stored in wooden cabinets that generate acetic acid vapour. Salt production depends on the moisture content of the object and the concentration of acetic acid in its surroundings. Furthermore, for thecotrichite to form the artefact must contain soluble chloride and nitrate salts.

A rapid method for the determination of cation exchange capacities of sandstones: preliminary data

Abstract A rapid and efficient single-extraction procedure for measuring cation exchange capacities in sandstones has been developed and tested. The method is based on the use of a SrCl2 (0.25 mol l−1) solution to displace the exchangeable cations. The cation exchange capacities (CEC) of three types of natural building stones were analysed, both in freshly quarried material and in weathered samples. Large differences in the sorptive properties of these materials were observed. The measurement of profiles of CEC in weathered sandstones revealed a significant decrease of CEC in the weathered zone close to the exposed surface, most likely reflecting the partial dissolution of clay minerals due to acid attack. CEC measurements appear to be a very sensitive indicator of chemical weathering profiles.

Quantitative determination of sources in urban aerosols using chemical receptor models

Abstract A chemical mass balance (CMB) receptor model was used to determine the contributions of primary particle sources to ambient total suspended particulate matter (TSP) in four German cities. The CMB model was applied to each of 210 weekly filter samples collected during a one year period (March 1981 – 1982). The concentrations of 25 elements in ambient air and source emissions were used to calculate the contributions of the sources to TSP. Primary particle sources were found to account on average for 30 – 40% of TSP. Mineral particles, traffic, and coal combustion proved to be the largest single contributors. Other industrial high temperature sources contribute only a minor fraction of TSP, but are major sources for many volatile trace elements. Traffic emissions represent an important source not only for Pb and Br, but also for Cu, Sb, Cr, Fe, and Zn.

Windrichtungsabhängige Probenahme und Multielementanalyse von Aerosolen zur besseren Beurteilung der Immissionsbelastung

SummaryThere is an increasing need for detailed investigation of air pollutant concentrations, e.g. for the determination of transport rates of airborne particulates in testing dispersion models or for source apportionment studies. Because there is a variety of variables determining ambient levels of aerosol constituents, especially meteorological parameters, it is rather difficult to obtain representative values for atmospheric pollutant levels, e.g. well defined mean concentrations, if low sampling frequencies with periodic measurements are used. A new sampling system for better evaluation of air pollutant measurements with a High Volume Sampler controlled by wind direction and wind speed is described. The aerosol samples collected on membrane filters of 1.2 μm mean pore diameter are digested with a mixture of perchloric, nitric, and hydrofluoric acid. For multielement analysis Inductively Coupled Plasma Emission Spectrometry (ICP-AES) and Atomic Absorption Spectrometry with Atomization in the Graphite Furnace (GF-AAS) were used. The analysis of wind directed samples collected in Hamburg showed, that there is significant increase of ambient elemental concentrations due to emissions of several industrial sources.ZusammenfassungBei Immissionsuntersuchungen werden zunehmend differenzierte Aussagen gefordert, wie beispielsweise der spezifische Beitrag einzelner Emittenten oder die Transportraten für partikuläre Schadstoffe bei der Validierung von Ausbreitungsmodellen. Werden für solche Untersuchungen Aerosolproben nur stichprobenartig gesammelt, so lassen sich weitergehende Informationen nur mit erheblichem Aufwand gewinnen. Zur besseren Beurteilung von Immissionsbelastungen durch Aerosole wurde ein Analysenverfahren ausgearbeitet, das bereits bei der Probenahme Richtung und Geschwindigkeit des horizontalen Windes berücksichtigt und zur Steuerung eines High-Volume-Samplers benutzt. Zur Abtrennung und Anreicherung des Aerosols aus der suspendierenden Meßluft werden großflächige Membranfilter verwendet. Weiterhin werden die Bedingungen für den naßchemischen Aufschluß der Meßfilter mit einem Gemisch aus HNO3, HClO4 und HF vorgestellt. Für die Multielementanalyse der Aerosolproben wird eine Kombination von Atomemissionsspektrometrie (ICP-AES) und Atomabsorptionsspektrometrie (Graphitrohrofen-AAS) erfolgreich eingesetzt. Mit der verwendeten Probenahmetechnik konnte bereits mit relativ wenigen Messungen eine signifikante Erhöhung der Immissionskonzentration durch die Emissionen des Hamburger Industriegebietes nachgewiesen werden.

Salt efflorescence on pottery in the Athenian Agora: A closer look

Abstract Salt contamination in the ceramic collection of the Athenian Agora, American School of Classical Studies, Greece, was confronted for the first time by the fulltime conservation staff that was appointed in 1979. A review is presented of the examination and analysis of the salt contaminants for their identification and of simulation tests to determine their source(s) and mode of formation since 1990. In the analytical campaigns of 1992 and 1994, calclacite (Ca(CH3COO)Cl·5H2O) (ICCD 12-0869) and calcium acetate hemihydrate (Ca(CH3COO)2·0.5H2O) (ICCD 19-0199) were identified with X-ray diffraction and polarized light microscopy and examined with the environmental scanning electron microscope. The various means with which to mitigate the contamination and the crystallization-deliquescence cycles, e.g. consolidation, desalination, and climate control, were also studied. The article focuses on the processes involved in the formation of acetate salt compounds with the publication of the first solubility and deliquescence diagrams of the Ca(CH3COO)2–CaCl2–H2O system at 25°C. Comparisons are drawn with recent work carried out on thecotrichite (Ca3(CH3COO)3Cl(NO3)2·7H2O). The course of action adopted by the conservation staff of the Athenian Agora to combat efflorescence has been termination of cleaning with hydrochloric acid and desalination as a remedial measure in lieu of the costly replacement of wooden cabinets with enameled steel storage cases for the extensive ceramic collection (52,000 catalogued ceramics). Volatile acetic acid concentrations in wooden storage cases in the collection have been found to range from 1039 ± 20 to 1267 ± 20 µg/m3 (400 to 500 ppb) at 25°C. Since 1979, all newly excavated ceramics and all ceramics exhibiting efflorescence in the collection have been routinely desalinated. No efflorescence has formed on the desalinated objects. Various methods of mitigation such as controlling the RH are also discussed.

Crystal Growth and Phase Equilibria in Porous Materials

In numerous research areas there is considerable interest in the phase changes occurring in pore solutions. First, the pressure generated by crystal growth of salts in confined spaces of porous materials is generally recognized as a major damage mechanism. Second, dissolved salts strongly affect the moisture retention and transport properties of porous media. This report briefly reviews recent advances in the treatment of phase equilibria of salts in porous substrates. The first part deals with the theory of crystallization pressure. In the second part model approaches for the calculation of thermodynamic properties in mixed electrolyte solutions and the calculation of phase equilibria are discussed.