A new structure-affinity relationship for TCDD receptor binding

We have investigated the capacity of various indoles to inhibit specific binding of [1,6-³H]2,3,7,8-tetrachlorodibenzo- -dioxin ([³H]TCDD) in rat liver cytosol, as analyzed by electrofocusing in polyacrylamide gels. Of these indoles, indolo[3,2- ]carbazole was the most active. The IC₅₀ value for TCDD receptor binding of indolo[3,2- ]carbazole as well as for 2,3,7,8-tetrachlorodibenzofuran was 3.6 nM. We have also studied the influence on binding exerted by introduction of some substituents on indolo[3,2- ]carbazole. Substitution with methyl groups at the 5 and 11 positions resulted in an increased affinity (IC₅₀ 1.2 nM) for the TCDD receptor as compared to the parent compound. Computer-supported molecular structure studies indicated that if the van der Waals radii of atoms are included, a rectangle of 6.8 × 13.7 Å may account for the binding of high-affinity ligands to the TCDD receptor.     

Common Patterns of Ecosystem Breakdown Under Stress

Ecosystems, despite their diversity, respond to stress in similar ways. The major pressures which cause the transformation of systems from healthy states to pathological states are classified into four groups: physical restructuring, overharvesting, waste residuals, and the introduction of non-native species. Signs of Ecosystem Distress Syndrome (EDS) are briefly examined in three contrasting ecosystems: desert grasslands, the Great Lakes, and the Baltic Sea. The issue is raised as to the difficulty in discerning between healthy ecosystems, recovering from a natural disturbance, and those ecosystems that have lost their original resilience due to anthropogenic stress. Knowledge of site history and a rigourous monitoring program are important in the evaluation of EDS. An assessment of how ecosystem services are affected is indicative of the consequences to the human component of ecosystems. Management strategies which are employed to mitigate the signs of EDS are usually initiated after resilience is lost or the ecosystem has transformed to an alternate, stress-induced, stable state. It is proposed that preventive strategies measure signs of EDS that serve as early warning signals, combined with "fitness tests" that measure ecosystem response to natural perturbations. The fitness test for ecosystems is based on the premise that unstressed systems are more resilient to natural disturbances than stressed systems.     

Multivariate characterization of polycyclic aromatic hydrocarbons using semi-empirical molecule orbital calculations and physical data

Multivariate characterization of 60 polycyclic aromatic hydrocarbons (PAHs) was performed using data from literature and semi-empirical molecular orbital calculations. This dataset was analyzed by principal component analysis and projections to latent structures by means of partial least square. The PAHs were found to distribute in the chemical domain in several groups mainly governed by the number of aromatic rings and the number of five-membered rings. The multivariate model and training set was used to predict GC retention times on a non-polar column (DB-5). Using a 2(4) experimental design on the principal components of the chemical characterization model, a test set of PAHs was selected dependent on the distribution in the chemical domain of the PAHs. Such a test set is expected to improve selection of PAHs for future testing and modeling of both biological and chemical responses. Although the model of GC retention times was good, the precision was however not good enough for practical use.     

Heavy metal surveys in Nordic lakes; concentrations, geographic patterns and relation to critical limits

In the autumn of 1995, coordinated national lake surveys were conducted in the Nordic countries, including Russian Kola. The 11 metals (Pb, Cd, As, Zn, Cu, Ni, Co, Fe, Mn, Cr, V) investigated in nearly 3000 lakes have generally low concentrations and distinct geographical patterns. Direct and indirect influence of long-range transported air pollution is the major important factor for distribution of Pb, Cd, Zn and to a certain degree Co. Total organic carbon (TOC) concentrations in lakes are important for Fe and Mn but also to a certain degree for As, Cr and V. Bedrock geology is the major controlling factor for Cu and Ni, with the exception of areas around the smelters in the Kola peninsula, where the Cu and Ni concentrations in lakes are very high due to local airborne pollution. Bedrock and surficial geology is also an important factor for controlling the concentrations of As, Co, Cr and V. The results indicate that heavy metal pollution in lakes is a minor ecological problem on a regional scale in the Nordic countries.     

Conflict resolution by participatory management: remote sensing and GIS as tools for communicating land-use needs for reindeer herding in northern Sweden

When seeking to resolve complex land-management issues, geographical assessment of resources that are in short supply or in dispute can aid the communication of knowledge and the understanding among and between different stakeholders. In this paper, we illustrate how remote sensing and GIS can be used to gather and compile information regarding land-use activities and patterns among reindeer herders and other land users (forestry, mining, tourism, etc) in northern Sweden. The project represents a novel user-oriented effort largely based on the work carried out by the principal end user, i.e. the reindeer herders themselves. The basis for development of land-use plans for reindeer husbandry, was the following: to collect and digitally systemize traditional ecological and landscape knowledge of reindeer habitat use; to integrate this information with results from field inventories and satellite-based vegetation classifications; to map activities of other land users. The resulting land-use plans provide information that can facilitate consultation between the reindeer herders and other stakeholders and can facilitate operational work in reindeer management. This project can serve as a model for participatory involvement and planning, bringing indigenous knowledge and advanced remote-sensing techniques together in an interactive process.     

Applications of the industrial ecology concept in a research project: Technology and Climate Change (CLIMTECH) Research in Finland

This contribution to the Journal of Cleaner Production special issue ‘Applications of Industrial Ecology’ is based upon an extensive literature review, which produced four criteria to characterise research on the concept of industrial ecology (IE). The criteria are (1) material and energy flows, (2) systems improvement, (3) systems adaptation and (4) change management. The criteria were analysed against the six subject areas of the Technology and Climate Change (CLIMTECH) Research Programme in Finland to identify the applications of the concept of industrial ecology. The results of the analysis contribute (a) to the debate on the characteristics of the emerging concept of IE, (b) show IE characteristics of a large Finnish research project in the field of climate change mitigation and (c) invite scholars in the field to study the observed unclear and fuzzy role of the concept of IE in practical research project work. Responses to this article are encouraged for publication in the future issues of Journal of Cleaner Production.     

Modelling long-term cation supply in acidified forest stands

A dynamic soil chemistry model was used to explain the observed decrease in soil base saturation between 1949 and 1984 at three stands in southern Sweden. The results show that acid deposition has caused soil acidification. The model, SAFE (Soil Acidification in Forest Ecosystems), includes the fundamental physical processes such as leaching and accumulation, and chemical processes such as cation exchange, mineral weathering, nutrient uptake and solute equilibrium reactions. The sources and sinks of base cations in the soil system were quantified, showing that weathering, deposition of base cations and depletion of exchangeable base cations supply cations to the soil solution in similar amounts in the upper 1 m during the acidification phase. This demonstrates that budget studies alone cannot be used to distinguish between long-term capacity to resist acidification, represented by weathering, from short-term buffering caused by cation exchange.     

Nutrient kinetics modeled from time series of substrate depletion and growth: dissolved silicate uptake of Baltic Sea spring diatoms

We estimated silicate uptake kinetics for 8 spring diatom species using a model based on time series measurements of the depletion of dissolved silicate (DSi) and increases in biomass. Furthermore, the carbon: nitrogen: silicate stoichiometric relationships and maximum growth rates were determined. Differences in DSi uptake kinetics and maximum growth rate were distinct among the species. All the most common diatom species (Chaetoceros wighamii, Pauliella taeniata, Skeletonema costatum and Thalassiosira baltica) were relatively lightly silicified and had variable but relatively low half-saturation constants (K _s ), indicating that they are well adapted to low DSi concentrations. The less common Diatoma tenuis and Nitzschia frigida had higher K _s values, suggesting that they are more vulnerable to DSi limitation. The much used nitrogen:silicate ratio of 1 for marine diatom biomass was too low for most of the examined species, while a ratio of 2–3 seems to be more appropriate for these Baltic Sea species.     

The use of sewage sludge as remediation for imidacloprid toxicity in soils

Environmental Science and Pollution Research - This study investigated the influence of the sewage sludge (SS) soil amendment on the chronic toxicity of imidacloprid (through the seed dressing...     

Chain-Length Shortening of Methyl Ethyl Hydroxyethyl Cellulose: An Evaluation of the Material Properties and Effect on Foaming Ability

During the past century, plastics have become a natural element in our every-day life. Lately however, an awareness about the fossil origin and often non-degradable nature of many plastics is rising. This has resulted in the emergence of some bio-based and/or biodegradable plastics, often produced from renewable resources. One possible candidate for bioplastics production could be found in cellulose. This paper aims at contributing information regarding a cellulose derivative, which could possibly be used in foamed plastics applications. Therefore, the reduction of the chain-length of a methyl ethyl hydroxyethyl cellulose (MEHEC), assessed by size exclusion chromatography, and the effect of chain-length on the foaming behaviour were studied. The foaming was accomplished with a hot-mould technique using aqueous polymer solutions. The generated steam was here used as the blowing agent and important parameters were polymer concentration and solution viscosity. The density of the produced foams was assessed and was in some cases comparable to that of commodity foams. It was found that reducing the chain-length enabled an increase of the initial polymer concentration for the foaming process. This is believed to be beneficial for creating more structurally stable foams of this type.