Pastoralists' responses to variation of rangeland resources in time and space.

We explore the response of pastoralists to rangeland resource variation in time and space, focusing on regions where high variation makes it unlikely that an economically viable herd can be maintained on a single management unit. In such regions, the need to move stock to find forage in at least some years has led to the evolution of nomadism and transhumance, and reciprocal grazing agreements among the holders of common-property rangeland. The role of such informal institutions in buffering resource variation is well documented in some Asian and African rangelands, but in societies with formally established private-property regimes, where we focus, such institutions have received little attention. We examine agistment networks, which play an important role in buffering resource variation in modern-day Australia. Agistment is a commercial arrangement between pastoralists who have less forage than they believe they require and pastoralists who believe they have more. Agistment facilitates the movement of livestock via a network based largely on trust. We are concerned exclusively with the link between the characteristics of biophysical variation and human aspects of agistment networks, and we developed a model to test the hypothesis that such a link could exist. Our model builds on game theory literature, which explains cooperation between strangers based on the ability of players to learn whom they can trust. Our game is played on a highly stylized landscape that allows us to control and isolate the degree of spatial variation and spatial covariation. We found that agistment networks are more effective where spatial variation in resource availability is high, and generally more effective when spatial covariation is low. Policy design that seeks to work with existing social networks in rangelands has potential, but this potential varies depending on localized characteristics of the biophysical variability.     

Nativ-basierte Grundöle für die Produktion von Kühlschmierstoffen

Aims and Scope

Compared to mineral oil products, cooling lubricants based on fatty acid esters have technological advantages. Moreover, they are more environmentally compatible and make a contribution to a sustainable economy. Nevertheless, they are rarely applied in practice, because of their comparably high price, that is based on raw-material and synthesis costs. Alternatives concerning raw-materials and synthesis pathways are considered and properties of resulting ester products are compared.

Methods

The investigations aimed at three fatty acid-2-ethyl-hexylesters that were synthesized in an enzymatic-catalytic routine based on peanut oil, suet, and waste edible fat and at esters that were conventionally produced from animal and plant fats and 2-ethyl-1-hexanol. Physical properties, fatty acid patterns, contents of free fatty acids, as well as oxidative and hydrolytic stabilities were determined. Thermolysis experiments were performed.

Results

The physical properties of the seven esters, density, viscosity, pourpoint, and flash point, were comparable and gave reason for the assumption, that the products could be used as basis oils in lubricant formulations. Hydrolysis stabilities of the esters were high and thermal stress did not point at high potential of hazardous compounds formation. Especially the enzymatic-catalytically produced esters showed deficits concerning oxidation stabilities and free fatty acid contents.

Outlook

For practice it will be necessary to define minimum qualities for raw-materials and resulting ester oils to be used as lubricant basis oils. Moreover, processes have to be developed, that yield high quality ester products from waste edible and animal fats without loosing the advantage of low-cost raw-materials by high production and refinement costs. Surely, one contribution is the further development of the energy-saving enzymtic alcoholysis for ester production.     

Neutral poly- and perfluoroalkyl substances in air and seawater of the North Sea

Concentrations of neutral poly- and perfluoroalkyl substances (PFASs), such as fluorotelomer alcohols (FTOHs), perfluoroalkane sulfonamides (FASAs), perfluoroalkane sufonamidoethanols (FASEs), and fluorotelomer acrylates (FTACs), have been simultaneously determined in surface seawater and the atmosphere of the North Sea. Seawater and air samples were taken aboard the German research vessel Heincke on the cruise 303 from 15 to 24 May 2009. The concentrations of FTOHs, FASAs, FASEs, and FTACs in the dissolved phase were 2.6–74, <0.1–19, <0.1–63, and <1.0–9.0 pg L^?1, respectively. The highest concentrations were determined in the estuary of the Weser and Elbe rivers and a decreasing concentration profile appeared with increasing distance from the coast toward the central part of the North Sea. Gaseous FTOHs, FASAs, FASEs, and FTACs were in the range of 36–126, 3.1–26, 3.7–19, and 0.8–5.6 pg m^?3, which were consistent with the concentrations determined in 2007 in the North Sea, and approximately five times lower than those reported for an urban area of Northern Germany. These results suggested continuous continental emissions of neutral PFASs followed by transport toward the marine environment. Air–seawater gas exchanges of neutral PFASs were estimated using fugacity ratios and the two-film resistance model based upon paired air–seawater concentrations and estimated Henry's law constant values. Volatilization dominated for all neutral PFASs in the North Sea. The air–seawater gas exchange fluxes were in the range of 2.5?×?10³–3.6?×?10⁵ pg m^?2 for FTOHs, 1.8?×?10²–1.0?×?10⁵ pg m^?2 for FASAs, 1.1?×?10²–3.0?×?10⁵ pg m^?2 for FASEs and 6.3?×?10²–2.0?×?10⁴ pg m^?2 for FTACs, respectively. These results suggest that the air–seawater gas exchange is an important process that intervenes in the transport and fate for neutral PFASs in the marine environment.     

A short-cut method for assessing absorbents for post-combustion carbon dioxide capture

A short-cut method for the estimation of the minimum regeneration energy and optimum solvent flow rate in post-combustion carbon dioxide capture by absorption is presented. It is developed for comparing solvents of which only little thermo-physical data is known. The closed absorber–desorber cycle is described by an equilibrium stage model (modified Kremser equation with discretized equilibrium curves). The method can be implemented in any mathematical toolbox or as stand-alone solution. The only required input is the solubility data at absorber and desorber conditions, the heat of absorption and heat capacities. The caloric data may be estimated. The method was applied to monoethanolamine (MEA) and two solvents from the EU-project CASTOR. Comparisons with experimental results from pilot-plant studies with MEA show that the method, despite its simplicity, gives reasonable results. The method should also be useful in other applications where absorbents, of which only little data is available, need to be screened.     

Polyfluorinated compounds in ambient air from ship- and land-based measurements in northern Germany

Neutral volatile and semi-volatile polyfluorinated organic compounds (PFC) and ionic perfluorinated compounds were determined in air samples collected at two sites in the vicinity of Hamburg, Germany, and onboard the German research vessel Atair during a cruise in the German Bight, North Sea, in early November 2007. PUF/XAD-2/PUF cartridges and glass fiber filters as sampling media were applied to collect several fluorotelomer alcohols (FTOH), fluorotelomer acrylates (FTA), perfluoroalkyl sulfonamides (FASA), and perfluoroalkyl sulfonamido ethanols (FASE) in the gas- and particle-phase as well as a set of perfluorinated carboxylates (PFCA) and sulfonates (PFSA) in the particle-phase. This study presents the distribution of PFC in ambient air of the German North Sea and in the vicinity of Hamburg for the first time. Average total PFC concentrations in and around Hamburg (180 pg m^?3) were higher than those observed in the German Bight (80 pg m^?3). In the German Bight, minimum–maximum gas-phase concentrations of 17–82 pg m^?3 for ΣFTOH, 2.6–10 pg m^?3 for ΣFTA, 10–15 pg m^?3 for ΣFASA, and 2–4.4 pg m^?3 for ΣFASE were determined. In the vicinity of Hamburg, minimum–maximum gas-phase concentrations of 32–204 pg m^?3 for ΣFTOH, 3–26 pg m^?3 for ΣFTA, 3–18 pg m^?3 for ΣFASA, and 2–15 pg m^?3 for ΣFASE were detected. Concentrations of perfluorinated acids were in the range of 1–11 pg m^?3. FTOH clearly dominated the substance spectrum; 8:2 FTOH occurred in maximum proportions. Air mass back trajectories, cluster, and correlation analyses revealed that the air mass origin and thus medium to long range atmospheric transport was the governing parameter for the amount of PFC in ambient air. Southwesterly located source regions seemed to be responsible for elevated PFC concentrations, local sources appeared to be of minor importance.     

Metal accumulation in soil arthropods in relation to micro-nutrients

Nine species of soil arthropod collected at two sites of different pollution levels were compared for concentrations of seven different elements (Ca, Cd, Cu, Fe, Mn, Pb, Zn) and correlations between the different elements were calculated. Significant effects of site on element concentrations of the animals were found for cadmium, iron, manganese and zinc, whereas calcium, copper and lead concentrations showed no significant difference between the sites. Significant differences between the species were found for all metal. The pattern of accumulation was comparable for some of the metals. Correlations were found between calcium, iron, manganese and lead concentrations and between zinc and cadmium concentrations of the species. No significant correlations were found for copper. The study showed that species can not be easily categorised as accumulators or non-accumulators; the pattern depends on the metal.