Bioassay zur Bestimmung von TCDD-Toxizitätsäquivalenten (TEQ) von Umweltproben und Reststoffen

Polychlorinated aromatic hydrocarbons (HAH) like 2,3,7,8-tetrachloro-p-dioxin (TCDD) elicit a multitude of toxic and biological effects. A common trait of these substances is their affinity for a cytosolic receptor protein and the subsequent induction of the synthesis of several gene products, including cytochrome P450 1A1 (CYP 1A1). In this publication we present a bioassay to determine the induction of CYP 1A1 as a sum parameter for the total toxic potential of critical halogenated compounds in complex environmental matrices. In order to eliminate compounds like polycyclic aromatic hydrocarbons (PAH) and naturally occurring substances which might interfere with the bioassay we developed a simple cleanup procedure. TEQ values derived from bioassay are in good agreement with those obtained from chemical analysis. This bioassay in combination with the simplified “single column” clean up represents a cost and time effective alternative to chemical analysis for the screening of large numbers of environmental matrices.     

Microbial diversity in the marine sponge Aplysina cavernicola (formerly Verongia cavernicola) analyzed by fluorescence in situ hybridization (FISH)

We have employed electronmicroscopical methods (SEM, TEM) to document the microbial community associated with the marine sponge Aplysina cavernicola (formerly Verongia cavernicola, class Demospongiae). Five dominant bacterial types were identified, three of which resemble the morphotypes originally described by Vacelet (1975). One bacterial type possesses morphological properties that are characteristic of the genus Planctomyces. In addition, morphologically uniform bacteria which reside inside the nuclei of host cells were observed. Using in situ hybridization with fluorescently labelled rRNA probes directed against known bacterial groups, the phylogenetic affiliation of the mesohyl bacteria was assessed. It could be shown that the vast majority of mesohyl bacteria belongs to the domain Bacteria with a low GC content. Among the Bacteria, the delta-Proteobacteria were most abundant, followed by the gamma-Proteobacteria and representatives of the Bacteroides cluster. Clusters of Gram-positive bacteria with a high GC content were also found consistently in low amounts. No hybridization signal was obtained with probes specific to the domain Archaea, to the alpha- and beta-Proteobacteria and to the Cytophaga/Flavobacterium cluster. This study describes for the first time the application of the “top-to-bottom approach” using 16S rRNA probes and in situ hybridization to assess the microbial diversity in Aplysina sponges. Received: 18 December 1998 / Accepted: 12 March 1999     

Bioindikation mit Wanderfalken

Goal and Scope

The Stockholm convention bans 12 prominent persistent organic pollutants (POPs), and the pertinent global monitoring programme recommends birds’ eggs as bio-indicators for the terrestrial food web. As top predators, Peregrine falcons are uniquely suited indicators because of their accumulating power for persistent and lipophilic compounds. On the other hand, the Peregrine falcon as a sentinel species was closer to extinction than other birds of prey. Only unremitting efforts of private omithologists throughout the past four decades in conjunction with the timely banning of organochlorine pesticides like DDT succeeded in saving the Peregrine population of Baden-Wueriternberg from extinction, in contrast to the Peregrine falcons of other German states or other European countries.

Methods

See vd Trenck et al. (2006).

Results and Conclusions

New results confirm the findings of the past long-term bio-monitoring. The main pollutants are PCBs (ca. 20 μg/g) and pp′-DDE (ca. 11 μg/g), the latter contributing >96% of all organochlorine pesticide residues (all concentrations on a dry matter basis). Both substances have followed a slightly increasing trend since 2004. The sum of the polychlorinated diphenyl ethers (PBDE) has fluctuated strongly in the past four years, and in 2006 amounted to 0.6 μg/g (mean without outliers), just as the mercury contamination of the eggs. PCB-156 as the main dioxin-like PCB followed with an average concentration of 0.35 μg/g. Only 10 out of 23 eggs analysed contained hexabromocyclododecane (HBCD) in measurable concentrations; the mean concentration of these eggs was 0.024 μg/g. Tetrabromobisphenol A (TBBA) was detected in all egg samples with a mean of 0.004 μg/g. Due to the many and diverse effects exerted by PCBs; the assessment of this group of compounds, with the aid of European and German regulations for food, proves to be a complex matter, which is currently in a state of flux. There is no doubt, however, that the mean pollution of the Peregrine eggs with toxic dioxin equivalents (WHO TEQ) has reached the no observed adverse effect level (NOAEL) known for chickens and osprey chicks, and the most polluted eggs exceed this threshold considerably. The toxic profile of PBDEs is similar to that of PCBs. They are known to promote tumour growth, to interfere with the thyroid hormone system resulting in toxicity for the neuronal development, to suppress the immune system, and to trigger stress reactions. Tests with highly purified BDE-47 have ruled out dioxin-like effects via Ah-receptor binding for this congener and such effects are therefore very unlikely for the whole class of compounds. At the present time, quantitative criteria for the assessment of the risk posed by PBDEs are not sufficiently reliable, and less so for HBCD and TBBA.

Recommendations and Perspectives

It is necessary to continue the bio-monitoring of POPs and similar pollutants in the terrestrial food web and to establish NOAELs as quantitative criteria for their assessment. Possible sources of dioxin-like PCBs and PCDD/Fs are to be pinpointed, and abatement measures are to be considered where background concentrations are significantly exceeded.     

Laboratory and field comparison of measurements obtained using the available diffusive samplers for ozone and nitrogen dioxide in ambient air

This study presents an evaluation of the extent of differences between measurements performed by O(3) and NO(2) diffusive samplers and by the reference methods for diffusive samplers commercially available. The tests were performed in an exposure chamber under extreme conditions of controlling factors and under field conditions. For NO(2), the results of the laboratory experiments showed that most of the diffusive samplers were affected by extreme exposure conditions. The agreement between the samplers and the reference method was better for the field tests than for the laboratory ones. The estimate of the uptake rate for the exposure conditions using a model equation improved the agreement between the diffusive samplers and the reference methods. The agreement between O(3) measured by the diffusive samplers and by the reference method was satisfactory for 1-week exposure. For 8-hour exposures, the diffusive samplers with high uptake rates quantified better the O(3) concentration than the samplers with low uptake rates. As for NO(2), the results of the O(3) field tests were in better agreement with the reference method than the ones of the laboratory tests. The field tests showed that the majority of diffusive samplers fulfils the 25% uncertainty requirement of the NO(2) European Directive and the 30% uncertainty requirement of the O(3) European Directive for 1-week exposure.     

Marine debris contamination along undeveloped tropical beaches from northeast Brazil

We hypothesize that floating debris leaving polluted coastal bays accumulate on nearby pristine beaches. We examined composition, quantities and distribution of marine debris along approximately 150 km of relatively undeveloped, tropical beaches in Costa do Dendê (Bahia, Brazil). The study site is located south of Salvador City, the largest urban settlement from NE Brazil. Strong spatial variations were observed. Plastics accounted for 76% of the sampled items, followed by styrofoam (14%). Small plastic fragments resultant from the breakdown of larger items are ubiquitous all over the area. Because the dominant littoral drift in Bahia is southward, average beach debris densities (9.1 items/m) along Costa do Dendê were threefold higher than densities previously observed north of Salvador City. River-dominated and stable beaches had higher debris quantities than unstable, erosional beaches. Areas immediately south of the major regional embayments (Camamu and Todos os Santos) were the preferential accumulation sites, indicating that rivers draining populous areas are the major source of debris to the study site. Our results provide baseline information for future assessments. Management actions should focus on input prevention at the hydrographic basin level rather than on cleaning services on beaches.     

Assessment of heavy metal releases from the use phase of road transport in Europe

An emission inventory was compiled for heavy metal air emissions from road transport in Europe (EU-40). For the database, country-specific data was taken such as the diesel and gasoline fuel consumption per country, the content of Pb in gasoline and diesel fuel and the share of different vehicle types. For tyre and brake wear emissions, average wear rates and heavy metal contents of different materials were used to develop emission factors for tyre and brake wear. It covers exhaust emissions (Pb from gasoline and diesel) as well as non-exhaust emissions (As, Cd, Cr, Ni and Pb from the wear of brake linings and vehicle tyres). The base year is 2000, and two scenarios were developed for 2010, a business as usual (BAU) scenario and a maximum feasible technical reduction (MFTR) scenario. Both result in a remarkable decrease in Pb exhaust emissions and a rising share of non-exhaust emissions. To assess the results, the inventory is (a) compared to an inventory compiled with a top-down approach that covers the same area and years but only emissions from combustion processes and (b) added to an inventory covering all sectors for heavy metal air emissions.