Description, assessment and meaning of vertical fluxes of matter within ecotopes: a systematic consideration

Ecotopes are the structural elements of landscapes for which matter and energy balances can be derived from measurements. Vertical flux densities are the typical entities governing their structure and function. Potential flux densities in ecotopes are discussed in detail using a complex circuit diagram that differentiates between transport and reaction columnar resistors. From this the locations and methods of measurement are deduced. Determination of flux densities between troposphere and phytosphere/pedosphere is restricted to the constant flux layer, by theory and practice.     

Catalytic TiO2 oxidation of ethanethiol for environmentally begnin air pollution control of sulphur compounds

Volatile organic compounds containing reduced sulphur such as thiols and thioethers are released mostly from biological activities and a number of manufacturing processes, such as papermaking and petroleum refining. Environmentally benign and cost-effective air pollution control technology for reduced sulphur compounds is still a topic of research, e.g., in pulp and paper industry. Due to its advantages, photocatalytic oxidation over titanium dioxide presents a potential alternative for the air treatment strategies. The temperature influence on the reaction pathway and kinetics of gas-phase photocatalytic oxidation and thermal catalytic decomposition of ethanethiol over Degussa P25 TiO₂ was established by a continuous flow method in a simple tubular reactor at temperatures from 373 to 453 K. Kinetic parameters for ethanethiol were: adsorption enthalpy −45 kJ mol⁻¹ and activation energy 42 kJ mol⁻¹. Sulphur dioxide, carbon monoxide, carbon dioxide, acetic acid and water were identified as by-products.     

Feeding responses of the tentaculate deposit-feederEupolymnia nebulosa (Annelida: Polychaeta): Influence of sexual maturity

Feeding responses of the tentaculate depositfeeding polychaeteEupolymnia nebulosa (Montagu) were studied by measuring rates of uptake of three different¹⁴C-labelled diatoms (unialgal cultures ofNavicula incerta Grunow,Nitzschia acicularis Wm Smith, andNitzschia sp.). Worms used during this study were collected in the harbor of Port-Vendre (Western Mediterranean) during August 1986 (immature worms) and December 1987 (mature worms). Uptake rates were affected both by the length of the experiments and by the nature of the food offered. The highest rate of uptake (2.98 10^–4 mg ashfree dry wt of algae mg^–1 dry wt of worms h^–1) was obtained during short-term experiments (4 h) with the smallest diatom (Nitzschia sp.). The lowest rate of uptake (0.21 10^–4 mg ash-free dry wt of algae mg^–1 dry wt of worms h^–1) was also obtained withNitzschia sp., but for a long-term (48 h) experiment. There was no significant difference between rates of uptake of immature and mature worms.     

Competition,defense and games between plants

Summary Coexistence of defended and undefended plants may be maintained by herbivory. In the present paper this phenomenon is analyzed by means of evolutionary game theory. The plants in the model play either a defensive or a non-defensive strategy and they interact indirectly: when a plant is grazed its competitive ability decreases, because of this a neighboring plant makes a profit. The solution to the game leads to three qualitatively different cases depending on whether the profit is equal for the two strategies, defended and undefended, or if the profit is higher for one type than for the other. When the results are applied to intea-specific interactions, the model predicts that polymorphic populations should be expected only under certain specific conditions. When the results are applied to inter-specific interactions, the model predicts either stable coexistence, i.e., increased diversity, or a paradoxical situation without increased diversity.Offprint requests to: M. Augner     

Air pollution exposure monitoring and estimation. Part II. Model evaluation and population exposure

The air pollution dispersion model EPISODE has been developed at the Norwegian Institute for Air Research (NILU) over the past several years in order to meet the needs of modern air quality management work in urban areas. The model has recently been used as a basis for exposure calculations of NOx and NO2 in order to assess the effects of different traffic diversion measures on health and well being for the residents in the V?lerenga-Ekeberg-Gamlebyen area in Oslo. Here we describe some results from the most recent evaluations of the model for NOx and NO2 at station Nordahl Brunsgate in Oslo for the period 1 October 1996-19 November 1996. In addition examples of population exposure calculations for Oslo performed during the winter period of 1995-96, are also presented.