Untersuchungen zum ?kotoxikologischen Sch?digungspotenzial und Erosionsrisiko von kontaminierten Sedimenten in staugeregelten Flüssen

Schwebstoffgebundene Schadstoffe werden durch Sedimentation der Wasserphase und damit der Verfügbarkeit für viele aquatischen Organismen entzogen. W?hrend bei durchschnittlichen hydrologischen. Verh?ltnissen die Freisetzung von Schadstoffen aus stabil gelagerten Sedimenten meist weitgehend unterbunden wird, besteht bei Hochwassereignissen die Gefahr einer Remobilisierung von kontaminierten Ablagerungen. In diesem Beitrag wird ein kombiniertes ?kotoxikologisches und hydraulisches Untersuchungssystem zur Untersuchung der ?kotoxikologischen Belastung und des Erosionsrisikos von Sedimenten vorgestellt. Der integrierte Ansatz wurde am staugeregelten Neckar angewendet, um das Sch?digungspotenzial und die Gefahr einer Remobilisierung an Sedimentbohrkernen der Stauhaltung Lauffen sowie an Schwebstoffen zweier extremer Hochwasser zu überprüfen. Für die Bohrkernsegmente unterhalb einer Erosionsdiskordanz konnte eine sprunghafte Zunahme der ?kotoxikologischen Belastung ermittelt werden. Bei Hochwasserereignissen mit einer 5-j?hrlichen Wiederkehrwahrscheinlichkeit (=HQ₅) k?nnen prinzipiell alle Sedimente, auch die st?rker kontaminierten und erosionsresistenteren Altsedimente, remobilisiert werden. W?hrend der Hochwasserereignisse (HQ₁₅ bis HQ₂₀) kam es zu einer deutlichen Erh?hung des cytotoxischen und mutagenen Sch?digungspotenzials der Schwebstoffe im Vergleich zu einem mittleren Hochwasser im Jahre 1995/96 (HQ₁) Dies schien zumindest teilweise auf die Remobilisierung hochkontaminierter Altsedimente zurückzuführen zu sein.     

Linking edge effects and patch size effects: Importance of matrix nest predators

The edge effect is usually considered to be the proximate cause of area sensitivity in forest birds. We tested if birds nesting in large patches are less vulnerable to the edge effect using a simple model that assumes an increase in patch size reduces the probability of a matrix predator moving to the core areas of forest and that larger perimeter/area ratios result in a higher number of matrix predators per unit of area. The probability of a nest being successful decreased asymptotically with an increase in either the patch penetration distance of predators or predator density, but those effects were reduced when patch size was increased. Large patches have a lower probability of being affected by an Allee effect and they can function as sink habitats only if penetration distance and predator density are largely increased. However, the transition from an Allee effect to a sink condition occurs with a small increase in penetration distance and predator density. Since birds nesting in large patches are less vulnerable to an increase in matrix predator populations, persistence of bird populations may be possible by increasing the size of habitat patches that can act as source populations.     

International retirement migration in the Alicante region,Spain: process,spatial pattern and environmental impacts

International retirement migration has become an increasing phenomenon in the Mediterranean region of Alicante, Spain. Through an interdisciplinary approach, relationships between the migration process, landscape change and environmental impacts are examined. Lifestyle-related perceptions and demands of UK retirees are studied as a major driving force of urbanisation. The extent and quality of the process is assessed by statistical and land use data analysis. Results reveal a distinctive spatial pattern of in-migration and the emergence of an archetypical landscape, consisting of a mosaic of remaining natural and urbanised landscape along the Mediterranean coast. The paper discusses the necessity of retirees' integration into sustainable planning and decision making.     

Environmental attitudes in less developed countries

Environmental policies in the developing countries are the product of circumstances quite different from those found in advanced nations. As a result, such policies have thus far been rather permissive. There is, however, considerable variance among developing countries in this respect, as well as substantial change over time. Not much evidence has been uncovered pointing to a migration of industry and mining to ‘pollution havens’ in developing countries—the reverse in fact seems to be the case. Nevertheless, it is likely that environmental policies will remain less stringent in developingthan developed countries for the foreseeable future. Indeed, the gap may well widen substantially.     

Estimation and validation of PM2.5/PM10 exhaust and non-exhaust emission factors for practical street pollution modelling

In order to carry out efficient traffic and air quality management, validated models and PM emission estimates are needed. This paper compares current available emission factor estimates for PM₁₀ and PM_2.5 from emission databases and different emission models, and validates these against eight high quality street pollution measurements in Denmark, Sweden, Germany, Finland and Austria.The data sets show large variation of the PM concentration and emission factors with season and with location. Consistently at all roads the PM₁₀ and PM_2.5 emission factors are lower in the summer month than the rest of the year. For example, PM₁₀ emission factors are in average 5–45% lower during the month 6–10 compared to the annual average.The range of observed total emission factors (including non-exhaust emissions) for the different sites during summer conditions are 80–130 mg km⁻¹ for PM₁₀, 30–60 mg km⁻¹ for PM_2.5 and 20–50 mg km⁻¹ for the exhaust emissions.We present two different strategies regarding modelling of PM emissions: (1) For Nordic conditions with strong seasonal variations due to studded tyres and the use of sand/salt as anti-skid treatment a time varying emission model is needed. An empirical model accounting for these Nordic conditions was previously developed in Sweden. (2) For other roads with a less pronounced seasonal variation (e.g. in Denmark, Germany, Austria) methods using a constant emission factor maybe appropriate. Two models are presented here.Further, we apply the different emission models to data sets outside the original countries. For example, we apply the “Swedish” model for two streets without studded tyre usage and the “German” model for Nordic data sets. The “Swedish” empirical model performs best for streets with studded tyre use, but was not able to improve the correlation versus measurements in comparison to using constant emission factors for the Danish side. The “German” method performed well for the streets without clear seasonal variation and reproduces the summer conditions for streets with pronounced seasonal variation. However, the seasonal variation of PM emission factors can be important even for countries not using studded tyres, e.g. in areas with cold weather and snow events using sand and de-icing materials. Here a constant emission factor probably will under-estimate the 90-percentiles and therefore a time varying emission model need to be used or developed for such areas.All emission factor models consistently indicate that a large part (about 50–85% depending on the location) of the total PM₁₀ emissions originates from non-exhaust emissions. This implies that reduction measures for the exhaust part of the vehicle emissions will only have a limited effect on ambient PM₁₀ levels.     

Assessing biodegradation benefits from dispersal networks

The performance of biodegradation of organic pollutants in soil often depends on abiotic conditions and the bioavailability of these pollutants to degrading bacteria. In this context, bacterial dispersal is an essential aspect. Recent studies on the potential promotion of bacterial dispersal by fungal hyphae raised the idea of specifically applying fungal networks to accelerate bacterial degradation processes in situ. Our objective is to investigate these processes and their performance via simulation modelling and address the following questions: (1) Under what abiotic conditions can dispersal networks significantly improve bacterial degradation? and (2) To what extent does the spatial configuration of the networks influence the degradation performance? To answer these questions, we developed a spatially explicit bacterial colony model, which is applied to controlled laboratory experiments with Pseudomonas putida G7 organisms as a case study. Using this model, we analyzed degradation performance in response to different environmental scenarios and showed that conditions of limited bacterial dispersal also limit degradation performance. Under such conditions, dispersal networks have the highest potential for improving the bioavailability of pollutants to bacteria. We also found that degradation performance significantly varies with the spatial configuration of the dispersal networks applied and the time horizon over which performance is assessed. Regarding future practical applications, our results suggest that (1) fungal networks may dramatically improve initially adverse conditions for biodegradation of pollutants in soil, and (2) the network's spatial structure and accessibility are decisive for the success of such tasks.