First report on the uptake of automobile catalyst emitted palladium by European eels (Anguilla anguilla) following experimental exposure to road dust.

Following the introduction of automobile catalysts in the middle of the 1980s in Germany there is an increasing emission of the platinum-group-metals platinum, palladium (Pd) and rhodium. Still, it remains unclear if these metals are bioavailable for aquatic animals and to which extent they become accumulated by the aquatic biosphere. Because of analytical problems in detecting Pd in small biological samples the present investigation concentrates on the bioavailability of this metal. To answer the question of a Pd uptake by aquatic organisms experimental studies were conducted with European eels maintained in water containing road dust at a concentration of 10 kg/100 l. Following an exposure period of four weeks, samples of liver and kidney were analysed by total-reflection X-ray fluorescence analysis after co-precipitation of Pd with mercury. These experiments revealed an uptake of traffic related Pd by European eels which showed a mean liver Pd concentration of 0.18 +/- 0.05 ng/g (wet wt.), whereas the Pd concentration in the kidney ranged below the detection limit. Thus, in this study we can demonstrate for the first time that automobile catalyst emitted Pd is bioavailable for aquatic animals.     

Organochlorverbindungen in Eiern von Wanderfalken und anderen wild lebenden Vogelarten in Baden-Württemberg

Goal and Scope

Organochlorine pollutants such as some pesticides and polychlorinated biphenyls (PCBs), dioxins and furans (PCDD/F) are highly persistent compounds in the environment. As synthetic, man-made products they are not encountered in natural ecosystems. Due to their high lipid solubility these compounds can accumulate in animals and humans, where they may exert chronically toxic and carcinogenic effects or disrupt endocrine functions and/or interfere with reproduction. Sound environmental stewardship demands continuous monitoring of such substances, assessment of their ecotoxicological risk, and reduction of excessive risk by setting appropriate standards.

Methods

The analysis of birds’ eggs is one method for the detection of organochlorine pollutants in ecosystems. In the German state of Baden-Wuerttemberg eggs of some bird species, especially Peregrine falcons, have been collected and analysed for selected persistent organic pollutants [total DDT (dichlorodiphenyl-trichloroethane), HCB (hexachlorobenzene), HCEP (heptachloroepoxide), HCH (hexachlorocyclohexane), PCBs] since the 1970s. Long-term continuous investigations yield data concerning temporal changes and regional differences in the pollution of the bio-indicators.

Results and Conclusion

Dioxin-like PCBs and total DDT were the most prominent pollutants. The Peregrine falcon (Falco peregrinus) was the most polluted bird species within the project. During the 1970s and 1980s all of the mentioned substances showed an encouraging decrease, undoubtedly because their use was banned in Germany. Analyses for PCDD/F in a small number of Peregrine falcon eggs from the period of 2000 to 2003 revealed the high level of pollution of these samples with dioxin toxicity equivalents (WHO-TEQ) from PCB and PCDD/F, which in all eggs reached the no observed effect level (NOEL) determined in osprey chicks and surpassed this threshold fivefold in the most polluted one.. Because of their great variability the pollutant concentrations in the eggs were difficult to interprete in some cases. Based on the results for the Peregrine falcon eggs of the years 2001 to 2003 a statement concerning the regional distribution of DDT and PCBs in Baden-Wuerttemberg could be made and depicted on the map. Because of their high lipid content, birds’ eggs are generally well suited as bio-indicators for the accumulation of persistent and lipophilic compounds.

Recommendations and Perspective

In spite of the significant decline of the organochlorine concentrations in the eggs of the birds investigated, the present situation is still alarming. Too many of the analytical data continue to exceed the respective national and EU-wide limit values for food and feed, and in the case of dioxin equivalents even lie above the assumed action threshold in the indicator organism. Therefore it is necessary to continue the bio-monitoring in Baden-Wuerttemberg in order to be able to recommend reduction measures where appropriate.     

Volatile carbonylic compounds in downtown Santiago, Chile

Formaldehyde, acetaldehyde, acetone, propanal, butanal, 2-butenal, 3-methylbutanal, hexanal, benzaldehyde, 2-methylbenzaldehyde, and 2,5-dimethylbenzaldehyde were measured during six spring days at downtown Santiago de Chile. Measurements were performed 24h/day and averaged over three hour periods. The averages of the maxima (ppbv) were, formaldehyde: 3.9+/-1.4; butanal: 3.3+/-3.4; acetaldehyde: 3.0+/-0.9; acetone: 2.4+/-1.0; 2-butenal: 0.56+/-0.52; propanal: 0.46+/-0.21; benzaldehyde: 0.34+/-0.3; 3-butanal: 0.11+/-0.05; hexanal: 0.11+/-0.08; 2-methylbenzaldehyde: 0.08+/-0.05; 2,5-dimethylbenzaldehyde: 0.05+/-0.03. Aliphatic aldehydes (C1-C3) are strongly correlated among them and weakly with primary (toluene) and secondary (ozone plus nitrogen dioxide or PAN) pollutants. In particular, the correlation between acetaldehyde and propanal values remains even if diurnal and nocturnal data are considered separately, indicating similar sources. All these aldehydes present maxima values in the morning (9-12h) and minima at night (0-3h). The best correlation is observed when butanal and 2-butenal data are considered (r=0.99, butanal/2-butenal=6.2). These compounds present maxima values during the 3-6h period, with minima values in the 0-3h period. These data imply a strong pre-dawn emission. Other aldehydes show different daily profiles, suggesting unrelated origins. Formaldehyde is the aldehyde whose concentration values best correlate with the levels of oxidants. The contribution of primary emissions and photochemical processes to formaldehyde concentrations were estimated by using a multiple regression. This treatment indicates that (32+/-16)% of measured values arise from direct emissions, while (79+/-23)% is attributable to secondary formation.     

Degradation of macrolide antibiotics by ozone: a mechanistic case study with clarithromycin

Macrolide antibiotics are widely used (in the order of 1g per person per year). They pass the body largely unchanged and are also not degraded in wastewater treatment plants. With not too much effort, they may be eliminated from their effluents by ozonation. The macrolide antibiotics have all a dimethylamino group at one of the carbohydrate residues in common. This functional group is the target of the ozone reaction, and clarithromycin has been selected here for a more detailed study. Since only the free amine reacts with ozone, the rate of reaction is pH dependent (at pH 7: k = 4 x 10(4) M(-1) s(-1)). In analogy to the ozonolysis of trimethylamine, the main reaction is a transfer of an O-atom yielding the N-oxide (identified by HPLC/MS-MS). A minor product (10%, based on formaldehyde yields) is demethylated clarithromycin (identified by HPLC/MS-MS). The dimethylamino group is thought to be essential for the binding of the macrolide antibiotics to their target. As a consequence, chemical changes of this functional group, notably the formation of the N-oxide that is no longer a proton acceptor, inactivates these drugs as assayed by the suppression of the growth of Pseudomonas putida. This is most important for wastewater treatment, as mineralization of clarithromycin by ozone would require 100 times as much ozone.     

Residues of dioxins (PCDD/Fs) and PCBs in eggs, fat and livers of laying hens following consumption of contaminated feed

Laying hens were fed with feed from the Belgian dioxin incident diluted ten-fold with non-contaminated feed, resulting in concentrations of 61 ngTEQkg(-1) PCDD/Fs, 23 ngTEQkg(-1) non-ortho PCBs, 116 ngTEQkg(-1) mono-ortho PCBs and 3.2 mgkg(-1) of the seven indicator PCBs. Following exposure for seven days, feed was replaced by non-contaminated feed for a period up to six weeks. Concentrations of PCDD/Fs in eggs showed a maximum of 214 pgTEQg(-1) fat after nine days and decreased to 44 pgTEQg(-1) after seven weeks. Dioxin concentrations in abdominal fat of chickens killed just after the last treatment, or after 1, 3 or 6 weeks on clean feed were 69, 84, 54 and 41 pgTEQg(-1) fat, respectively. Concentrations in livers decreased more rapidly, being 35, 7, 4 and 3 pgTEQg(-1) tissue, respectively. In both eggs and tissues, total TEQ concentrations were 3-4 times higher. Concentrations of the seven indicator PCBs in egg fat showed a stronger decrease with concentrations of 16.5 microgg(-1) at the peak (day 9) and 2.2 microgg(-1) after seven weeks. Corresponding concentrations in abdominal fat were, respectively, 4.6 and 2.6 microgg(-1) fat, and in livers 0.77 and 0.14 microgg(-1) tissue. The ratio of indicator PCBs to PCDD/Fs in feed was 52200. In eggs this ratio was initially higher (85000), but decreased towards 50000 after six weeks on clean feed. In abdominal fat the ratio varied between 49000 and 67000. In livers, the ratio was initially low (22000) but increased to 45000 towards the end of the study. It is concluded that the behaviour of PCDD/Fs and PCBs in laying hens is comparable and that the use of indicator PCBs appears to be a good alternative for PCDD/Fs but only in the case of co-exposure to both PCBs and PCDD/Fs, such as in incidents with PCB oil.     

Effects of the antidepressant mianserin in zebrafish: molecular markers of endocrine disruption

Due to their environmental occurrence and intrinsic biological activity, human pharmaceuticals have received increasing attention from environmental and health agencies. Of particular, ecotoxicological concern are drugs that affect nervous- and endocrine-systems. Zebrafish genome-wide oligo arrays are used to collect mechanistic information on mianserin-induced changes in gene expression in zebrafish. Gene expression analysis in brain and gonad tissue clearly demonstrated the estrogenic activity of mianserin and its potency to disrupt normal endocrine (estrogenic) signaling, based on induction of molecular biomarkers of estrogenicity (e.g., vitellogenin1 and zona pellucida proteins). The possible mechanism underlying this estrogenic activity of mianserin is disturbance of the Hypothalamo-Pituitary-Gonadal (HPG) axis by direct interference of mianserin with the serotonergic and adrenergic systems in the brain of zebrafish. Taking into account the importance of the HPG-axis, and considering the concept of 'critical window of exposure', our results reveal the importance for more elaborate testing of endocrine disruptive effects of aquatic antidepressants at different lifestages and during longer exposure periods (e.g., life cycle studies). Although there is a low concordance between the gene expression results in this study and previous cDNA microarray hybridizations, the global mechanistic expression patterns are similar in both platforms. This argues in favor of pathway-driven analysis of gene expression results compared to gene-per-gene analysis.     

Development and application of a sediment toxicity test using the benthic cladoceran Chydorus sphaericus

This study reports on the development and application of a whole sediment toxicity test using a benthic cladoceran Chydorus sphaericus, as an alternative for the use of pelagic daphnids. A C. sphaericus laboratory culture was started and its performance under control conditions was optimised. The test was firstly validated by determining dose-response relationships for aqueous cadmium and copper and ammonia, showing a sensitivity of C. sphaericus (96 h LC(50) values of 594 microg Cd/L, 191 microg Cu/L and 46 mg ammonia/L at pH 8) similar to that of daphnids. Next, sediment was introduced into the test system and a series of contaminated sediments from polluted locations were tested. A significant negative correlation between survival and toxicant concentrations was observed. It is concluded that the test developed in the present study using the benthic cladoceran C. sphaericus is suitable for routine laboratory sediment toxicity testing.     

The effect of turbation on zinc relocation in a vertical floodplain soil profile

Turbation is hypothesized to affect the redistribution of heavy metals in polluted floodplain soils by effects on mobility. This hypothesis was tested in microcosms by turbation of zinc-spiked sediment top layers. Manual turbation caused a fast decrease of the zinc content in the upper 15 cm of the soil, even though turbation was only applied to the upper two centimetres. It was especially zinc attached to colloid and organic matter particles that was redistributed from the top layer. Percolation processes resulted in the attached zinc being drained to depths of more than 15 cm. The decrease in zinc content of the topsoil was even stronger in combination with inundation. No indications were found for the redistribution of zinc as a result of an increase of the extractability with 0.01 M CaCl2 or changes in pH. The findings suggest that mechanical turbation and bioturbation may redistribute heavy metals from topsoils in polluted floodplains just after inundation as observed in these turbation experiments.     

Occurrence and fate of the phytotoxin juglone in alley soils under black walnut trees

Juglone (5-hydroxy-1,4-napthoquinone) is a chemical released by walnut trees, which can be toxic at various levels to several plant species. A balance among competing source and sink mechanisms and rates will ultimately determine whether juglone is capable of attaining sufficient levels to be allelopathic to intercrops in a walnut tree agroforestry system. In this study, juglone's release, accumulation, and decline in soil are explored using data from soil beneath a black walnut tree (Juglans nigra L) alley cropping system, greenhouse pot studies, and laboratory sorption/degradation studies. Juglone pore water concentrations estimated from extracts of surficial soil from beneath the alley cropping system exceeded the lowest solution culture toxicity levels reported for some plants of 10(-7) M, but did not exceed the inhibition threshold reported for typical intercrops such as maize and soybeans 10(-5) M. Further assessment of the likely persistence of juglone in soils indicated that juglone is both microbially and abiotically degraded, and that it will be particularly short-lived in soils supporting microbial activity. However, walnut seedlings planted in sand-filled pots clearly showed that juglone is released in measurable quantities to the soil's rhizosphere. Therefore, juglone accumulation in low fertility soils is plausible, and may still be worthy of consideration in management of alley agroforestry systems.