Total arsenic, lead, and cadmium levels in vegetables cultivated at the Andean villages of northern Chile.

Various vegetables (broad beans, corn, potato, alfalfa and onion) were sampled in northern Chile, Antofagasta Region. They are the basis of human nutrition in this region and of great relevance to human health. This region is characterized by volcanic events (eruptions, thermal springs, etc.). Most of the vegetables cultivated in this area enter the local markets for a population of approximately 4000 people, whose ancestors were mainly atacameños and quechuas (local indigenous people). The cadmium and lead in these foods was determined by differential pulse anodic stripping voltammetry (DPASV). Results indicate that the highest concentration of Pb and Cd are in the potato skin, while the edible part of the potatoes contained a lower concentration of these metals. The INAA analyses of As in the vegetables from Socaire and Talabre, two towns located close to active volcanoes (e.g. Lascar), show a very high As content: 1850 microg/kg in corn (Socaire) and 860 microg/kg in potatoes (+ skin) (Talabre). These values exceed the National Standard for arsenic (500 microg/kg) by approximately 400% and 180%, respectively. In general, the data show a concentration of Pb greater than Cd with the potential for some vegetables to accumulate heavy metals, The values, expressed in fresh weight, vary from 0.2 to 40 microg/g for Cd and from 0.6 to 94 microg/g for Pb. These concentration intervals, except that of arsenic, are within the recommended standards in the Food Sanitary Regulation (Decree 977), which, expressed as fresh weight, must be equal to or smaller than 500 microg/kg for Pb. There is no legal standard for Cd.

Total arsenic, lead, cadmium, copper, and zinc in some salt rivers in the northern Andes of Antofagasta, Chile.

The pre-Andes water in the region of Antofagasta is the main drinking and irrigation water source for approximately 3000 Atacameña (indigenous) people. The concentration for soluble elements (filtration in field through a 0.45-microm filter) was: Cd < 0.1 ng/ml; Pb < 0.5 ng/ml; and Zn and Cu between 1 and 10 ng/ml. In particulate material the concentrations were: for Cd < 0.1 ng/ml; for Pb < 0.3 ng/ml; and for Zn and Cu less than 1 ng/ml. The total content of these elements is far below the international recommendations (WHO) and the national standards (N. Ch. 1333 mod. 1987 and 409-1 of 1984). On the other hand, in some rivers a very high arsenic concentration was found (up to 3000 ng/ml) which exceed more than 50 times the national standard. In order to verify the analytical results, inter-laboratory and comparison with different determination methods have been done.

Environmental specimen banking in Germany--present state and further challenges.

The program of the German Environmental Specimen Bank has been expanded recently and its current status is briefly described. Selected results which have been obtained during the long term permanent operation of this project since 1985 are presented. Moreover, further aspects of environmental data evaluation and assessment are discussed.

The Jülich Environmental Specimen Bank.

The environmental specimen bank of the Federal Republic of Germany represents the modern form of a systematically designed archive for the preservative storage of selected environmental specimens. Major aims of environmental specimen banks are: (i) retrospective identification and quantification of environmental chemicals including those not known at the time of storage; (ii) retrospective replicate analysis of samples stored under preservative conditions for the determination of inorganic elements or organic compounds already examined; and (iii) retrospective control of the success of legislative environmental protection measures in handling chemicals regarded as hazardous for man and the environment. Results of the environmental specimen bank at Jülich by the Institute of Applied Physical Chemistry, Research Centre Jülich, KFA, obtaining the initiated legislative regulations providing environmental pollution, are already proved for various compartments.

Surfactants and complexing agents: new tasks for specimen banking?

Surfactants and complexing agents are chemical products that are released into the environment in large amounts after being used in cleaning processes, mineral flotation, pesticide formulations, etc. Although these compounds are largely degraded during sewage treatment in industrialized countries, significant amounts will be found in sediments or sewage sludges. Furthermore, large concentrations of these compounds can be found in small rivers and brooks in the vicinity of outfalls of sewage treatment plants. Since these compounds can be expected to alter the organic matrix of the soil (surfactants) or to remobilize heavy metals from soils or sediments (complexing agents), their occurrence in the environment and their effects have to be investigated to estimate their long-term risk potential. This could be a new task for specimen banking. To this end, (a) sensitive and specific detection methods for surfactants and complexing agents have to be developed at concentrations relevant to environmental occurrence, and (b) the effect of surfactants and complexing agents on the distribution of organic and inorganic pollutants in environmental compartments has to be investigated. Preliminary investigations show significant synergistic or antagonistic effects of various surfactants on the adsorption of pollutants at clay minerals.

[Physicochemical fundamentals on the cleaning of hard surfaces (author's transl)]. / Physikalisch-chemische Grundlagen der Reinigung harter Oberflächen.

The primary process in the cleaning of hard surfaces is the adsorption of the active substance of the detergent at the interfaces: liquid/gas, liquid/liquid, liquid/solid. This primary step in the cleaning process induces secondary processes which in turn are responsible for the soil removal from the surface of the substrate. The first requirement for a cleaning effect is that the dirt and the substrate be well wetted by the cleaning solution as a result of a reduction in surface tension and of the adsorption at the solid/liquid interface. The further secondary processes which effect the removal of dirt vary considerably, depending on the type of dirt (e.g. oils, pigments). In the case of oily and greasy dirt, rolling-up penetration, formation of mixed phases, emulsification and solubilization are of importance. For pigments, the surface pressure of the adsorption layer and the electrostatic repulsion are the determining factors. The processes of pigment dispersion, emulsification and solubilization are, in addition, extremely important for the stabilization of the dirty wash bath and the prevention of deposits on the substrate. The essential active substances of the detergents are surfactant and complexing agents, the first being unspecifically adsorbed by hydrophobic interactions, and the latter specifically by polar interactions. They influence one another mutually and are responsible for an optimal cleaning effect when they occur in suitable mixing ratios; the special constitutional characteristics of the individual surfactant and complexing agents, must also be considered.