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981.
The organic sector is in an ongoing, but somewhat ambiguous, process of differentiation. Continuing growth has also entailed intensified competition and the emergence of conventional structures within the sector. Producers are under pressure to adapt their terms of production to these developments, bearing the risk that the original values and principles of organic farming may become irrelevant. To confront these tendencies and maintain their position on the market, organic producers and processors have launched a number of organic–fair initiatives. As some consumers attach importance to ethical aspects of consumption, these actors sense market opportunities in such quality differentiation. This article presents results of a study on current organic–fair criteria, as formulated by such initiatives. All of them define standards of distributive, procedural and informational fairness, with fair prices for producers and processors and long-term agreements being core standards. We show that distributive and procedural fairness are closely linked. Although organic–fair initiatives and their main protagonists focus on external fairness, such as fair prices for farmers, thus far internal concerns, such as minimum wages or employee involvement, are of less importance. The initiatives exemplify the differentiation of quality-oriented organic food producers in highly competitive markets. They have the potential to revitalise the original values of the sector and contribute significantly to ethical standardization therein. In order to make a substantial contribution to future development of the sector, a critical examination of aspects of internal fairness as well as the formulation of appropriate standards in this field is recommended. 相似文献
982.
983.
Craig?L.?StrongEmail author John?F.?Leys Mike?R.?Raupach Joanna?E.?Bullard Hélène?A.?Aubault Harry?J.?Butler Grant?H.?McTainsh 《Environmental Fluid Mechanics》2016,16(5):1065-1083
Wind erosion processes affect soil surfaces across all land uses worldwide. Understanding the spatial and temporal scales of wind erosion is a challenging undertaking because these processes are diverse and highly variable. Wind tunnels provide a useful tool as they can be used to simulate erosion at small spatial scales. Portable wind tunnels are particularly valued because erosion can be simulated on undisturbed soil surfaces in the field. There has been a long history of use of large portable wind tunnels, with consensus that these wind erosion simulation tools can meet real world aerodynamic criteria. However, one consequence of striving to meet aerodynamic reality is that the size of the tunnels has increased, making them logistically difficult to work with in the field and resulting in a tendency to homogenise naturally complex soil surfaces. This homogenisation is at odds with an increasing awareness of the importance that small scale processes have in wind erosion. To address these logistical and surface homogenisation issues we present here the development and testing of a micro wind tunnel (MWT) designed to simulate wind erosion processes at high spatial resolution. The MWT is a duct-type design—0.05 m tall 0.1 m wide and with a 1.0 m working section. The tunnel uses a centrifugal motor to suck air through a flow‐conditioning section, over the working section and then through a sediment collection trap. Simulated wind velocities range from 5 to 18 m s?1, with high reproducibility. Wind speeds are laterally uniform and values of u * at the tunnel bed (calculated by measuring the pressure gradients within the MWT) are comparable with those of larger tunnels in which logarithmic profiles can be developed. Saltation sediment can be added. The tunnel can be deployed by a single person and operated on slopes ranging from 0 to 10°. Evidence is presented here that the MWT provides new and useful understanding of the erodibility of rangelands, claypans and ore stockpiles. 相似文献
984.
Javier Houspanossian Raúl Giménez Germán Baldi Marcelo Nosetto 《Journal of Land Use Science》2016,11(4):369-383
In this paper, we explored how aridity influences the regional deforestation and land-use patterns (i.e. crops/pastures) in South American Dry Chaco. To do this, we contrasted land use during last decade (2001–2012) with a spatially explicit aridity index, which we complemented with a crop water balance model. Land-use classifications were performed by considering the temporal variability of NDVI from MODIS satellites, showing that 40 and 60% of deforested land was assigned to crops and pastures, respectively. Results indicate that although the regional deforestation pattern was not associated with the aridity gradient, with drier areas similarly deforested as wetter areas, contrasting differences were observed in the use of this land, with crops mostly located (90%) in wetter areas and pastures evenly distributed across the whole aridity gradient. This research highlighted the strong effect of water limitations on the land-use option after deforestation and may help to set the basis for future land-use planning policies. 相似文献
985.
Christopher Young Sabine Hähndel Bonaventura Majolo Oliver Schülke Julia Ostner 《Behavioral ecology and sociobiology》2013,67(10):1665-1677
Dominant mammalian males should gain a reproductive advantage due to their greater fighting abilities. However, the extent to which they can monopolise access to females varies across species. In primates and recently other mammalian species, the Priority of Access (PoA) model is commonly used to measure the degree to which male rank and female receptive synchrony affect mating skew. Few studies have examined the factors which lead to deviations from the expectations of the model. Here, we investigate male mating skew in wild Barbary macaques (Macaca sylvanus). We examined four of the main factors which affect male mating success: the roles of male rank, female receptive synchrony, coalitionary activity and female behaviour. We found that male mating was skewed up the hierarchy, but there was a large deviation from the PoA model's expectations with high-ranked males not gaining as big a share as expected. Females frequently initiated sexual encounters, predominantly with mid-ranked males, increasing their mating success. Male coalitionary activity independently increased mating success. Frequent associations with females were costly to males as they were the targets of bridging coalitions, decreasing future mating opportunities for the targets. High-ranking males did not increase their mating success directly through bridging coalitions but acted to dilute the effects of female behaviour. By examining different factors affecting mating skew, we are able to show that alternative male and female mating strategies are effective in reducing the monopolisation potential of the dominant male. 相似文献
986.
Population growth and social/technological developments have resulted in the buildup of carbon dioxide (CO2) in the atmosphere and oceans to the extent that we now see changes in the earth’s climate and ocean chemistry. Ocean acidification is one consequence of these changes, and it is known with certainty that it will continue to increase as we emit more CO2 into the atmosphere. Ocean acidification is a global issue likely to impact marine organisms, food webs and ecosystems and to be most severely experienced by the people who depend on the goods and services the ocean provides at regional and local levels. However, research is in its infancy and the available data on biological impacts are complex (e.g., species-specific response). Educating future generations on the certainties and uncertainties of the emerging science of ocean acidification and its complex consequences for marine species and ecosystems can provide insights that will help assessing the need to mitigate and/or adapt to future global change. This article aims to present different educational approaches, the different material available and highlight the future challenges of ocean acidification education for both educators and marine biologists. 相似文献
987.
Hronn Egilsdottir Fanny Noisette Laure M.-L. J. Noël Jon Olafsson Sophie Martin 《Marine Biology》2013,160(8):2103-2112
Marine organisms inhabiting environments where pCO2/pH varies naturally are suggested to be relatively resilient to future ocean acidification. To test this hypothesis, the effect of elevated pCO2 was investigated in the articulated coralline red alga Corallina elongata from an intertidal rock pool on the north coast of Brittany (France), where pCO2 naturally varied daily between 70 and 1000 μatm. Metabolism was measured on algae in the laboratory after they had been grown for 3 weeks at pCO2 concentrations of 380, 550, 750 and 1000 μatm. Net and gross primary production, respiration and calcification rates were assessed by measurements of oxygen and total alkalinity fluxes using incubation chambers in the light and dark. Calcite mol % Mg/Ca (mMg/Ca) was analysed in the tips, branches and basal parts of the fronds, as well as in new skeletal structures produced by the algae in the different pCO2 treatments. Respiration, gross primary production and calcification in light and dark were not significantly affected by increased pCO2. Algae grown under elevated pCO2 (550, 750 and 1000 μatm) formed fewer new structures and produced calcite with a lower mMg/Ca ratio relative to those grown under 380 μatm. This study supports the assumption that C. elongata from a tidal pool, where pCO2 fluctuates over diel and seasonal cycles, is relatively robust to elevated pCO2 compared to other recently investigated coralline algae. 相似文献
988.
Arnold Schecter Justin A. Colacino Nirav Shah Olaf Päpke Mathias Opel Keyur Patel 《毒物与环境化学》2013,95(6):1053-1063
Levels of polybrominated diphenyl ether (PBDE) flame retardants have been increasing in humans and the environment for the past few decades. Human levels are markedly higher in the US than Europe. Although food appears to be a significant route of intake, food PBDE levels are not substantially higher in the US than Europe. House and office dust appear to be major routes of exposure with air believed to usually provide a lesser route of intake. Because there are very few measurements of airborne PBDE that have been performed in relevant microenvironments in the US, increased efforts to assess airborne PBDE in the US as sources of exposure are needed. This study reports, for the first time from a Southwestern US city in Texas, the results of measurements of airborne PBDE in multiple locations, two outdoor and six indoor (residential and office) from active air sampling with collection of a combination of both vapor- and particulate-phase PBDE. Higher PBDE levels were measured in indoor than outdoor air, which confirms previous findings. Of 11 measured congeners including BDE 209, total PBDE levels in two outdoor air samples were 112 and 125 pg m?3 and the indoor air levels ranged from 175 to 1232 pg m?3 with a median of 572 pg m?3. These findings suggest that sources of air contamination with PBDE may be similar in Texas as elsewhere in North America. However, more sampling is required to (1) better determine if this is the case and (2) attempt to characterize potential sources of PBDE contamination in both indoor and outdoor air by analysis of congener patterns. 相似文献
989.
Partitioning of native or anthropogenic heavy metals in solid and solution phases of soil is a result of network of several physico‐chemical reactions. The attainment of equilibrium between two phases is also regulated by biochemical processes. For practical purposes, the bioavailability of metal present in soil is predominantly regulated by the soil solution phase which is in dynamic equilibrium with the solid phase. The results of a model laboratory and greenhouse growth experiments have been used to investigate the effect of Cd‐ion concentrations (either in soil solution or in nutrient solution) on the growth and activities of microorganisms. The soil solution has been simulated by preparing a suspension of soil with 0.1 M NaNO3 (1: 2.5) equilibrated for two hours. Important conclusions are as follows: Increase in Cd‐ion concentration in soil solution or in nutrient solution induces corresponding adverse effect on the growth and activities of microorganisms. Thus, it seems that Cd‐ion concentration is a more sensitive indicator for assessing the effect of metal pollution upon the growth and activities of soil microorganisms in comparison to total Cd contents. During active microbial growth phase, a large part of the organically bound Cd was released in the soil solution which is largely bioavailable. This process is termed as mobilisation. There was momentary increase of Cd‐ion concentration in soil solution which intoxicated the growing organisms. After this stage, the Cd ions from the solution phase were removed by the newly formed solid phase (nonviable biomass) and were transformed in non‐available form. This process is termed as immobilisation. The consequences and importance of these results for practical agriculture and in deciding the limits or guidelines on the maximum tolerable metal load in soils are discussed. 相似文献
990.
To check the effect of possible deposition of organic contaminants in northern regions of the Earth due to atmospheric transport snow samples were collected in early March in 6 places in Russia and 4 in Finland including arctic territories. GC‐MS was used as an analytical tool to identify and quantify individual organic compounds belonging to the various classes. As a result more than 250 compounds were detected. The possible presence of more than 100 other priority pollutants from the US EPA list was also screened. 相似文献