Microanalytical trace element techniques (such as ion probe or laser ablation ICP-MS) are hampered by a lack of well characterized, homogeneous standards. Two silicate glass reference materials produced by National Institute of Standards and Technology (NIST), NIST SRM 610 and NIST SRM 612, have been shown to be homogeneous and are spiked with up to sixty one trace elements at nominal concentrations of 500 μg g-1 and 50 μg g-1 respectively. These samples (supplied as 3 mm wafers) are equivalent to NIST SRM 611 and NIST SRM 613 respectively (which are supplied as 1 mm wafers) and are becoming more widely used as potential microanalytical reference materials. NIST however, only certifies up to eight elements in these glasses. Here we have compiled concentration data from approximately sixty published works for both glasses, and have produced new analyses from our laboratories. Compilations are presented for the matrix composition of these glasses and for fifty eight trace elements. The trace element data includes all available new and published data, and summaries present the overall average and standard deviation, the range, median, geometric mean and a preferred average (which excludes all data outside ± one standard deviation of the overall average). For the elements which have been certified, there is a good agreement between the compiled averages and the NIST data. This compilation is designed to provide useful new working values for these reference materials.

A Compilation of New and Published Major and Trace Element Data for NIST SRM 610 and NIST SRM 612 Glass Reference Materials

Antimony in the environment: a review focused on natural waters: I. Occurrence

Heavy metal pollution is one of the most troublesome environmental problems faced by mankind nowadays. Copper, in particular, poses serious problems due to its widespread industrial and agricultural use. Unlike other heavy metals, such as cadmium, lead, and mercury, copper is not readily bioaccumulated and thus its toxicity to man and other mammals is relatively low. On the contrary, plants in general are very sensitive to Cu toxicity, displaying metabolic disturbances and growth inhibition at Cu contents in the tissues only slightly higher than the normal levels. The reduced mobility of Cu in soil and sediments, due to its strong binding to organic and inorganic colloids, constitutes, in a way, a barrier to Cu toxicity in land plants. In aqueous media, however, plants are directly exposed to the harmful effects of Cu and, thus, algae and some species of aquatic higher plants are more easily subjected to Cu toxicity. Excess Cu inhibits a large number of enzymes and interferes with several aspects of plant biochemistry, including photosynthesis, pigment synthesis, and membrane integrity. Perhaps its most important effect is associated with the blocking of photosynthetic electron transport, leading to the production of radicals which start peroxidative chain reactions involving membrane lipids. Copper effects on plant physiology are wide ranging, including interference with fatty acid and protein metabolism and inhibition of respiration and nitrogen fixation processes. At the whole plant level Cu is an effective inhibitor of vegetative growth and induces general symptoms of senescence. The high toxicity of Cu to plants has led to the evolution of several strategies of defense. Among the most important ones is the production of Cu-complexing compounds. Although the nature, structure, and function of these compounds is still controversial, they can be divided into two main groups: metallothionein-like compounds and phytochelatins. The latter appears to constitute the most widespread response of plants to stresses provoked by metals, including Cu.

Biochemical, physiological, and structural effects of excess copper in plants

Surface-active organic molecules are common constituents of atmospheric aerosol particles, raindrops, and snowflakes. If these compounds are present as surface films, transfer of gases into the atmospheric water systems could be impeded, evaporation could be slowed, and the aqueous chemical reactions could be influenced. To investigate these possibilities, we have reviewed the chemical literature pertaining to organic films on aqueous surfaces: their composition, structure, properties, and effects. We then review the surface-active organic compounds in atmospheric water. We report the results of new measurements of surface tension of aqueous solutions of common atmospheric organic compounds (β-pinene, n-hexanol, eugenol, and anethole) and demonstrate that the compounds produce films with properties similar to those of the more well known surfactants. We conclude that organic films are probably common on atmospheric aerosol particles and that they may occur under certain circumstances on fog droplets, cloud droplets, and snowflakes. If present, they will increase the lifetimes of aerosol particles, fog droplets, and cloud droplets, both by inhibiting water vapor evaporation and by reducing the efficiency with which these atmospheric components are scavenged. The presence of the films will not cause a significant reduction of solar radiation within the aqueous solution. It appears likely, however, that the transport of gaseous molecules into and out of the aqueous solution will be impeded by factors of several hundred or more when organic films are present. Since incorporated gas molecules provide much of the oxidizing potential of atmospheric water droplets, the organic films will play a major role in droplet chemistry by strongly inhibiting solution oxidation.

Organic films on atmospheric aerosol particles, fog droplets, cloud droplets, raindrops, and snowflakes

Antimony in the environment: A review focused on natural waters. III. Microbiota relevant interactions

In Fortsetzung einer fruheren Untersuchung zur Rolle der beiden kupferzeitlichen Bergwerke von Rudna Glava und Ai Bunar fur die Kupferversorgung Sudosteuropas wurden 290 Metallobjekte, sieben Malachitperlen, sowie 76 Proben von Kupfererzen und gediegen Kupfer, vorwiegend aus Bulgarien, hinsichtlich ihrer Spurenelementgehalte und Bleiisotopenverhaltnisse analysiert. Von den Artefakten datieren 258 in die Zeit vom spaten Neolithikum bis zur Proto-Bronzezeit und bilden zusammen mit 77 prahistorischen Kupferobjekten aus Serbien die Materialbasis fur die folgenden SchluBfolgerungen:
Aus dem Vergleich der chemischen Zusammensetzung von gediegen Kupfer und Metallartefakten aus Sudosteuropa laBt sich schlieBen, daB nur wenige Artefakte moglicherweise aus gediegen Kupfer, die uberwiegende Mehrheit jedoch aus verhuttetem Kupfer hergestellt wurde. Leider sind zeitgleiche Verhuttungseinrichtungen bisher noch nicht belegt.
Wahrend noch immer kein einziges prahistorisches Metallobjekt Rudna Glava zugeordnet werden kann, stimmen bei 32 Artefakten aus der mittleren und spaten Kupferzeit alle gemessenen Parameter mit denen der Erze von Ai Bunar uberein. Es ist besonders bemerkenswert, daB sich darunter vier Schwergerate von Plocnik befinden. Dagegen stammt kein einziges von 82 analysierten endkupferzeitlichen Artefakten von Ai Bunar. Damit ist es erstmals gelungen, die prahistorischen Abbauphasen dieser Lagerstatte indirekt zu datieren.
Wegen der chemischen und isotopischen Einheitlichkeit von zwei Artefaktgruppen schlieBen wier auf mindestens zwei weitere spatkupferzeitliche Abbauzentren, von denen wier eines in Prochorovo, ca. 80 km ostlich von Ai Bunar, vermuten. Das zweite Zentrum liegt mit hoher Wahrscheinlichkeit im Bereich um Medni Rid in der Nahe von Burgas am Schwarzen Meer.
Im westlichen Bereich unseres Untersuchungsgebietes haben wir bereits fruher die noch heute im Abbau befindliche Kupferlagerstatte von Majdanpek als Ursprung der meisten endkupferzeitlichen Artefakte aus Serbien identifiziert. Die neuen Ergebnisse legen nun einen Beginn der Abbautatigkeit bereits in der mittleren Kupferzeit nahe. Kupfer dieser Zusammensetzung findet sich auch entlang der Donau bis Tell ruse. Es deutet sich daher ein Handel mit Kupfer an, der vielleicht das Gegenstuk zum Handel mit Spondylus- und Dentaliummuscheln donauaufwarts bildete.
Das Auftreten von Kupfer von Ai Bunar in Serbien einerseits und von Majdanpek an der unteren Donau andererseits laBt auf eine Verbreitung der Metallgewinnung in relativ kurzer Zeit in ganz Sudosteuropa schlieBen. Obwohl das Kupfer aus Aibunar, Prochorovo (?) und Medni Rid vorwiegend in Ost- und Nordostbulgarien zu finden ist und das von Majdanpek vorwiegend in Westbulgarien und Serbien, hat es offenbar Austauschbeziehungen zwischen den beiden Regionen gegeben. Aus den analytischen Ergebnissen ist zusatzlich abzulesen, daB es noch weitere Produktionsstatten von Kupfer gegeben hat.

Prehistoric copper in Bulgaria: Its composition and provenance

Neutron activation analysis of metal ions in Langmuir—Blodgett multilayers of arachidic acid

The chemical fingerprinting of a plant demands the determination of a large number of elements at background level but also in polluted regions and in relation to other species. The most important stages of the development of plant fingerprints are mentioned in this paper and a short survey of the state of the art is presented. Examples on fingerprinting of lichens, mosses, Taraxacum officinale and Populus nigra‘Italica’ are presented.

Ivelin Kuleff

Papers

Prehistoric copper in Bulgaria: Its composition and provenance

Neutron activation analysis of metal ions in Langmuir—Blodgett multilayers of arachidic acid

Chemical fingerprinting of plants

Bromine, copper, manganese and lead content of the leaves of Taraxacum officinale (dandelion)

Screening of heavy metal pollution in Bulgaria using Populus nigra 'Italica'.