Zur Beständigkeit von Aluminiumchloridlösungen mit tridekameren Kationen (Al<Subscript><Emphasis Type="Bold">13</Emphasis></Subscript>)

Background, aim, and scopeThe focus of popular interest on the subject of acid rain has been on the effects, which it has on aquatic ecosystems. Aluminium toxicity and the bioavailability depend on the species of aluminium present. The cationic aluminium species are important for the phytotoxocity and for the precipitation of aluminium containing precipitate.Materials and methodsSpeciation diagrams of aqueous aluminium chloride solutions with tridecameric cations (Al₁₃) at room temperature as function of concentration (1·10^–1–1·10^–5 mol·l^–1 Al) and aging time (9 month) have been obtained from a kinetic method; these Ferron method offers a simple and inexpensive alternative for identification and quantification of aluminium cations.ResultsThe Al₁₃-cation stability decrease with decreasing concentration and increasing aging time.DiscussionPolynuclear aluminium species can be formed in nature by the dissolution of Al-containing minerals, as a consequence of surface water acidification, followed by neutralization process. The question of the occurrence of the tridecameric polycation (Al₁₃) in natural soil solutions and stream waters is of considerable interest.ConclusionsThe results are important on the occurrence of the Al₁₃ in natural waters, for the precipitation of aluminium species by acidification and for the aluminium phytotoxicity.Recommendations and perspectivesThis research suggests strongly that Al₁₃ should be negligible in natural soil and surface waters. The toxicity of Al₁₃ to plants and aquatic organism in natural conditions may be considered to be very low.     

The copper cycles of European countries

A comprehensive technological copper cycle treating a series of life stages (mining and processing, fabrication, utilization, and end of life) has been constructed for sixteen countries on the European continent for the year 1994. In this paper we draw on that information to present country-level copper cycles for a sampling of the countries. We then compare the countries on the basis of their relative and absolute copper production, import/export, usage, recycling, and losses to the environment, and go on to produce per capita assessments of flow and stock changes. Among the results of particular interest are: (1) country-level copper budgets possess features often different from the continental budgets of which they are a part. For example, Europe extracted only slightly more copper from mines than it deposited in landfills, while the mine to landfill flow ratio was about 11:1 in Poland and near zero in the United Kingdom; (2) Germany led all other countries in the group of sixteen in the absolute magnitude of every major copper flow (production, import, export, consumption, and waste generation, and in per capita flows of copper entering use and waste management), while the Benelux countries led all others in per capita flows for all other categories; (3) citizens of essentially all the countries discarded 1–3 kg Cu/year, mostly in obsolete electronics and end-of-life vehicles.     

The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia

I examined the decline of Ancient Murrelets ( Synthliboramphus antiquus ), a small, burrow-nesting seabird, at Langara Island. The island's seabird colony was historically one of the largest colonies of Ancient Murrelets in British Columbia—perhaps in the world—with an estimated 200,000 nesting pairs. I reviewed historical information and compared the results of surveys from 1981 and 1988 that employed the same census protocol. The extent of the colony, a potential index of population size, declined from 101 ha in 1981 to 48 ha in 1988. Burrow density increased during the same period, however, suggesting that the colony bad consolidated. In 1988, the population estimate was 24,200 ± 4000 (S.E.) breeding pairs compared to 22,000 ± 3700 in 1981. in 1988, 29% of the burrows that were completely searched contained bones of Ancient Murrelets. Bones were most common in burrows located in abandoned areas of the colony and were least common where burrow occupancy was high. The discovery of adult Ancient Murrelets killed in their burrows by introduced rats, combined with the high proportion of burrows with bones, suggests that rats ( Rattus rattus and R. norvegicus ) have contributed significantly to the decline of the population. In addition, the presence and activities of a salmon-fishing fleet in the 1950s and 1960s may also be linked to the decline of the Langara Ancient Murrelet population during that period because these fisheries are known to have caused heavy mortality through fatal light attraction and drowning in gill nets. The combined effects of ongoing predation by introduced rats and—to a lesser extent—previous, episodic fishery-induced mortality are probable causes for the population decline.     

Biodegradability of antineoplastic compounds in screening tests: influence of glucosidation and of stereochemistry

Some pharmaceuticals such as antineoplastics are carcinogenic, mutagenic, teratogenic and fetotoxic. Antineoplastics and their metabolites are excreted by patients into waste water. In laboratory testing the frequently used isomeric anti-tumour agents cyclophosphamide (CP) and ifosfamide (IF) were shown to be not biodegradable. They are not eliminated in municipal sewage treatment plants and therefore detected in their effluents. Structural related compounds are beta-D-glucosylisophosphoramidmustard (beta-D-Glc-IPM; INN = glufosfamide) and beta-L-glucosylisophosphoramidmustard (beta-L-Glc-IPM). beta-L-Glc-IPM has no antineoplastic effects whereas beta-D-Glc-IPM is active against tumours. In contrast to IF and CP and almost all other investigated antineoplastics beta-D-Glc-IPM is inherently biodegradable. Improved biodegradability of beta-D-Glc-IPM compared to IF shows that reducing the impact of pharmaceuticals on the aquatic environment is feasible by changing the chemical structure of a given compound exerting a similar mode of action and therapeutic activity. Stereochemistry may be crucial for pharmaceutical activity of the compounds as well as for its biodegradability in the environment.     

No evidence for visual context-dependency of olfactory learning in <Emphasis Type="Italic">Drosophila</Emphasis>

How is behaviour organised across sensory modalities? Specifically, we ask concerning the fruit fly Drosophila melanogaster how visual context affects olfactory learning and recall and whether information about visual context is getting integrated into olfactory memory. We find that changing visual context between training and test does not deteriorate olfactory memory scores, suggesting that these olfactory memories can drive behaviour despite a mismatch of visual context between training and test. Rather, both the establishment and the recall of olfactory memory are generally facilitated by light. In a follow-up experiment, we find no evidence for learning about combinations of odours and visual context as predictors for reinforcement even after explicit training in a so-called biconditional discrimination task. Thus, a ‘true’ interaction between visual and olfactory modalities is not evident; instead, light seems to influence olfactory learning and recall unspecifically, for example by altering motor activity, alertness or olfactory acuity.