Formation of secondary inorganic aerosols by power plant emissions exhausted through cooling towers in Saxony

Background, aim, and scope  The fraction of ambient PM₁₀ that is due to the formation of secondary inorganic particulate sulfate and nitrate from the emissions of two large, brown-coal-fired power stations in Saxony (East Germany) is examined. The power stations are equipped with natural-draft cooling towers. The flue gases are directly piped into the cooling towers, thereby receiving an additionally intensified uplift. The exhausted gas-steam mixture contains the gases CO, CO₂, NO, NO₂, and SO₂, the directly emitted primary particles, and additionally, an excess of ‘free’ sulfate ions in water solution, which, after the desulfurization steps, remain non-neutralized by cations. The precursor gases NO₂ and SO₂ are capable of forming nitric and sulfuric acid by several pathways. The acids can be neutralized by ammonia and generate secondary particulate matter by heterogeneous condensation on preexisting particles. Materials and methods  The simulations are performed by a nested and multi-scale application of the online-coupled model system LM-MUSCAT. The Local Model (LM; recently renamed as COSMO) of the German Weather Service performs the meteorological processes, while the Multi-scale Atmospheric Transport Model (MUSCAT) includes the transport, the gas phase chemistry, as well as the aerosol chemistry (thermodynamic ammonium–sulfate–nitrate–water system). The highest horizontal resolution in the inner region of Saxony is 0.7 km. One summer and one winter episode, each realizing 5 weeks of the year 2002, are simulated twice, with the cooling tower emissions switched on and off, respectively. This procedure serves to identify the direct and indirect influences of the single plumes on the formation and distribution of the secondary inorganic aerosols. Results and conclusions  Surface traces of the individual tower plumes can be located and distinguished, especially in the well-mixed boundary layer in daytime. At night, the plumes are decoupled from the surface. In no case does the resulting contribution of the cooling tower emissions to PM₁₀ significantly exceed 15 μgm⁻³ at the surface. These extreme values are obtained in narrow plumes on intensive summer conditions, whereas different situations with lower turbulence (night, winter) remain below this value. About 90% of the PM₁₀ concentrations in the plumes are secondarily formed sulfate, mainly ammonium sulfate, and about 10% originate from the primarily emitted particles. Under the assumptions made, ammonium nitrate plays a rather marginal role. Recommendations and perspectives  The analyzed results depend on the specific emission data of power plants with flue gas emissions piped through the cooling towers. The emitted fraction of ‘free’ sulfate ions remaining in excess after the desulfurization steps plays an important role at the formation of secondary aerosols and therefore has to be measured carefully.     

Increased sedentariness in European Blackbirds following urbanization: a consequence of local adaptation?

Urbanization changes local environmental conditions and may lead to altered selection regimes for life history traits of organisms thriving in cities. Previous studies have reported changes in breeding phenology and even trends toward increased sedentariness in migratory bird species colonizing urban areas. However, does the change in migratory propensity simply represent a phenotypic adjustment to local urban environment, or is it genetically based and hence the result of local adaptation? To test this, we hand-raised European Blackbirds (Turdus merula) from urban and forest populations, quantified their nocturnal activity and fat deposition covering two complete migratory cycles and examined the consequences of a reduced migratory propensity for the timing of gonadal development (a physiological measure of the seasonal timing of reproduction). Although nocturnal activities differed strikingly between fall and spring seasons, with low activities during the fall and high activities during the spring seasons, our data confirm, even in birds kept from early life under common-garden conditions, a change toward reduced migratoriness in urban blackbirds. The first score of a principal component analysis including amount of nocturnal activity and fat deposition, defined as migratory disposition, was lower in urban than in forest males particularly during their first year, whereas females did not differ. The results suggest that the intrinsic but male-biased difference is genetically determined, although early developmental effects cannot be excluded. Moreover, individuals with low migratory disposition developed their gonads earlier, resulting in longer reproductive seasons. Since urban conditions facilitate earlier breeding, intrinsic shifts to sedentariness thus seem to be adaptive in urban habitats. These results corroborate the idea that urbanization has evolutionary consequences for life history traits such as migratory behavior.     

Trade agreements,labour mobility and climate change in the Pacific Islands

Regional Environmental Change - The risks, pressures and threats on Small Island Developing States (SIDS) of the Pacific from climate change are often perceived by outsiders as overwhelming, both...     

TNT in Komposten und Flüssigkultur

The formation of aromatic amines was investigated using a summarized test (NEDA-test) during the composting of 2,4,6-trinitrotoluene (TNT) contaminated soil. In this test, the aromatic amines were diazolated and then coupled to N-1-Naphthyl-ethylenediamine-dihydrochloride (NEDA) to yield an azo dye which can be monitored photometrically. The test was calibrated for known TNT-metabolites with an active amine-group. Liquid samples from composting- and liquid-culture-experiments were analyzed by HPLC for these known metabolites. Moreover, the samples were monitored by the NEDA-test and the expected extinction of the TNT-metabolites found with amine function were extrapolated with the help of calibration curves. It was shown that substantial differences are obvious between the monitored and extrapolated values. After separation into polar and non-polar aromatic amines, it became clear that these differences are made by the polar aromatic amines. Polar aromatic amines, which are not detectable by presently available analytical tests, were generated during the composting of TNT-contaminated soils. Contaminated stagnant water, which was generated during anaerobization of a compost prephase, was treated aerobically for 70 days in a biofermenter. During this treatment TNT and its known metabolites were eliminated almost entirely. Simultaneously, the toxicity in the Lumis Tox-test decreased drastically. In striking contrast, the sum of aromatic amines decreased only to a minor extent. Moreover, the percentage of polar compounds from total amount of aromatic amines increased drastically from 48% to more than 95%. At present, the chemical identification of these polar compounds is still missing and is the object for further research.     

Nutrient Limitation in a Compost Biofilter Degrading Hexane

Abstract

A laboratory-scale compost-based biofilter was operated over a six-month period to study the requirements for removal of n-hexane from air. Hexane is a relatively short chain aliphatic hydrocarbon with a high Henry's coefficient and a low water solubility. Acclimation of the biofilter was slow, but removal efficiencies around 80% were achieved after one month of operation. However, performance decreased during the next two months of operation to 50% removal efficiency. Nutrient limitation was proposed as a reason for the decrease in reactor performance. After the addition of a concentrated nitrogen solution, reactor performance increased almost immediately to >99%. Removal efficiency remained above 99% for the following two months of operation at inlet concentrations of 0.7 g/m3 (200 ppmv), at superficial bed velocities approaching 50 m/h, and empty bed residence times of about one minute. Thus, nutrient availability may well limit biofilter performance even in compost- based units. It was shown that nutrients can be added effectively in a soluble form if compost quality is poor and a method is proposed for the evaluation of compost quality.     

Bewertung der Umweltgefährlichkeit von Stoffen

By sending a questionnaire to all companies of the pulp and paper, textile finishing and leather industries in Germany a study ascertained wastewater data concerning the general situation, treatment processes and specific amounts. With these data standard figures used in the EU for the assessment of chemical substances were checked. The volume flows of the industrial sewage treatment were determined for the facilities of all three branches which discharge their wastewater directly to the receiving waters. The 10 percentile score of these facilities amounted to only a quarter of the EU standard figure of 2,000 m³/d. This value is related to a standardised waste water treatment plant within the EU, which treated the wastewater of 200 l/d from 10,000 inhabitants. The analyses of the entire branch in each case yield dilution factors of 20–70% of the EU standard value of 10. Only the full tanning leather companies yielded a dilution factor of 10. The volume flows of the sewage treatment plants of the facilities discharging to the sewer system exceeds 2,000 m³/d in call cases.