Impact of photocatalytic remediation of pollutants on urban air quality

In the recent years, photocatalytic self-cleaning and “depolluting” materials have been suggested as a remediation technology mainly for NO _x and aromatic VOCs in urban areas. A number of products incorporating the aforementioned technology have been made commercially available with the aim to improve urban air quality. These commercial products are based on the photocatalytic properties of a thin layer of TiO₂ at the surface of the material (such as glass, pavement, etc.) or embedded in paints or concrete. The use of TiO₂ photocatalysts as an emerging air pollution control technology has been reported in many locations worldwide. However, up to now, the effectiveness measured in situ and the expected positive impact on air quality of this relatively new technology has only been demonstrated in a limited manner. Assessing and demonstrating the effectiveness of these depolluting techniques in real scale applications aims to create a real added value, in terms of policy making (i.e., implementing air quality strategies) and economics (by providing a demonstration of the actual performance of a new technique).

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Perfluorooctanoic acid and perfluorooctane sulfonate in the sediment of the Roter Main river, Bayreuth, Germany

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are widely distributed in aquatic ecosystems. Their sources are known but few studies about their accumulation potential in river sediments exist. The aim of this study is to assess the concentrations of PFOA and PFOS in sediments in relation to their levels in river water receiving effluent from a waste water treatment plant (WWTP). PFOS accumulates by a factor of about 40 relative to river water, PFOA only up to threefold. In contrast to previous suggestions, in this case the enrichment on sediment is not correlated to the total organic carbon contents.     

90Sr, 137Cs and (239,240)Pu concentration surface water time series in the Pacific and Indian Oceans--WOMARS results

Under an IAEA's Co-ordinated Research Project "Worldwide Marine Radioactivity Studies (WOMARS)" 90Sr, 137Cs and (239,240)Pu concentration surface water time series in the Pacific and Indian Oceans have been investigated. The Pacific and Indian Oceans were divided into 17 latitudinal boxes according to ocean circulation, global fallout patterns and the location of nuclear weapons test sites. The present levels and time trends in radionuclide concentrations in surface water for each box were studied and the corresponding effective half-lives were estimated. For the year 2000, the estimated average 90Sr, 137Cs and (239,240)Pu concentrations in surface waters of the Pacific and Indian Oceans varied from 0.1 to 1.5 mBq/L, 0.1 to 2.8 mBq/L, and 0.1 to 5.2 microBq/L, respectively. The mean effective half-lives for 90Sr and 137Cs in surface water were 12+/-1 years for the North, 20+/-1 years for the South and 21+/-2 years for the Equatorial Pacific. For (239,240)Pu the corresponding mean effective half-lives were 7+/-1 years for the North, 12+/-4 years for the South and 10+/-2 years for the Equatorial Pacific. For the Indian Ocean the mean effective half-lives of 137Cs and (239,240)Pu were 21+/-2 years and 9+/-1 years, respectively. There is evidence that fallout removal rates before 1970 were faster than those observed during recent decades. The estimated surface water concentrations of 90Sr, 137Cs and (239,240)Pu in latitudinal belts of the Pacific and Indian Oceans for the year 2000 may be used as the average levels so that any new contribution from nuclear facilities, nuclear weapons test sites, radioactive waste dumping sites and from possible nuclear accidents can be identified.     

Conclusions on plutonium separation from atmospheric krypton-85 measured at various distances from the Karlsruhe reprocessing plant

For wide-area atmospheric monitoring, krypton-85 is the best indicator for clandestine plutonium separations. The detection and false alarm rates were determined from weekly samples at five different distances from the Karlsruhe reprocessing plant between 1985 and 1988. The detection rate for the separation of 4 kg of plutonium per week was found to be as high as 80-90% at a distance of less than 1 km, 70% at 5 km, 40% at 39 km, and 15% at 130 km. At distances up to 40 km, the false alarm rate is less than 3.5%. On average, the fuel released 28 TBq krypton-85 per kg plutonium. For weapons-grade plutonium, the krypton signal would be lower by a factor of 2. Hence, the given percentages correspond to the detection probabilities for the separation of a significant quantity (8 kg) of plutonium per weekly sample under the specific meteorological conditions of the WAK. The minimum separation rates that could have been detected are 2 gram of weapons-grade plutonium per week at a distance of less than 1 km, 40 g/week at 5 km, 200 g/week at 39 km, and 1000 g/week at 130 km.     

Erprobung und Erfolgskontrolle eines Phytoremediations-verfahrens zur Sanierung Sprengstoff-kontaminierter Böden

Results of a field experiment (please refer to Warrelmann et al. 2000a) document TNT-degradation and regeneration after the establishment of a phytoremediation. Various approaches are included in a complex monitoring system, which are conducted in the field (nitroaromatics in soil, seepage water, and plants; soil fauna; soil fungi; decomposition) as well as in the lab (a battery of 6 biotests). The data document a high heterogeneity of the TNT-contamination, a rapid initial decrease and a mediocre displacement of nitroaromatics in plants and seepage water. The initial rapid transformation of TNT to aminodinitrotoluenes ceases significantly after 3 months. Results of the biotest battery allow a sophisticated assessment of soil toxicity; the results from the soil ecological field investigations make the long-term effects of TNT-contamination likely. In a third part of the series of articles, a synopsis and judgement of the project will be delivered.     

Aktive Stoffe als Handlungsoption gegen die Verschleppung von Organismen durch Seeschiffe?

Background and Scope

The marine shipping lanes have become the most important path for the invasion of foreign aquatic organisms. The increasing global trade results in an increase in the number of marine vessels. Without any protective measures, with every ship carrying foreign organisms the risk of biological invasions will rise.

Results

The International Martime Organization (IMO) of the United Nations developed a convention to reduce the transfer of organisms with ballast water. After the entry-into-force of this convention the fleet of the world has to be equipped with effective ballast water management technology before 2016. This article discusses potential options for action. To comply with the limit values of the ballast water convention, the current state of the art demands the use of active substances. Any decision on the approval of active substances used for ballast water treatment and the environmental impact assessment lies with the IMO. Proposed to day are UV-radiation, active chlorine, active oxygen, the creation of biocides through electrolysis and a change in gases contained in the ballast water. The technologies and the potential risks are presented.

Conclusions

Despite the introduction of an approval procedure by IMO any reliable assessment of the real risks involved in the use of biocides is impossible, as the risk assessment approaches have still to be developed. On the regulatory level, the main focus in data requirements for the risk assessment is on a comprehensive testing of the toxic potential of the biocides proposed. Strategies for the identification and evaluation of the chemical resulting from the treatment of limnic, marine and brackish water are not fully developed. An integrating assessment of risks involved in the introduction of foreign organisms versus the toxic effects of the substances used or created during treatment is still missing.     

Darwin’s warm little pond revisited: from molecules to the origin of life

All known cosmic and geological conditions and laws of chemistry and thermodynamics allow that complex organic matter could have formed spontaneously on pristine planet Earth about 4,000 mya. Simple gasses and minerals on the surface and in oceans of the early Earth reacted and were eventually organized in supramolecular aggregates and enveloped cells that evolved into primitive forms of life. Chemical evolution, which preceded all species of extant organisms, is a fact. In this review, we have concentrated on experimental and theoretical research published over the last two decades, which has added a wealth of new details and helped to close gaps in our previous understanding of this multifaceted field. Recent exciting progress in the molecular and genetic analyses of existing life, in particular microorganisms of ancient origin, even supports the possibility that a cellular, self-reproducing common ancestor might be assembled and resurrected in anaerobic cultures at some time in the future. Charles Darwin did not, and indeed, could not, address and specify the earliest phases of life which preceded the Origin of Species. However, in a famous letter, he sketched “a warm little pond with all sorts of… (chemicals, in which) …a protein was chemically formed.” We try to trace the impact of his charming clear-sighted metaphor up to the present time.