Protected areas (PAs) are key elements for biodiversity conservation and ecosystem services. Brazil has the largest PA system in the world, covering approximately 220 million ha. This system expanded rapidly in the mid‐1990s to the mid‐2000s. Recent events in Brazil, however, have led to an increase in PA downgrading, downsizing, and degazettement (PADDD). Does this reflect a shift in the country's PA policy? We analyzed the occurrence, frequency, magnitude, type, spatial distribution, and causes of changes in PA boundaries and categories in Brazil. We identified 93 PADDD events from 1981 to 2012. Such events increased in frequency since 2008 and were ascribed primarily to generation and transmission of electricity in Amazonia. In Brazilian parks and reserves, 7.3 million ha were affected by PADDD events, and of these, 5.2 million ha were affected by downsizing or degazetting. Moreover, projects being considered by the Federal Congress may degazette 2.1 million ha of PA in Amazonia alone. Relaxing the protection status of existing PAs is proving to be politically easy in Brazil, and the recent increase in frequency and extension of PADDD reflects a change in governmental policy. By taking advantage of chronic deficiencies in financial and personnel resources and surveillance, disputes over land tenure, and the slowness of the Brazilian justice, government agencies have been implementing PADDD without consultation of civil society. If parks and reserves are to maintain their integrity, there will need to be investments in Brazilian PAs and a better understanding of the benefits PAs provide. Degradación, Reajuste, Eliminacióm de las Listas y Reclasificación de Áreas Protegidas en Brasil 相似文献
This paper challenges the limited models of childhood, conflict and relief which determine most humanitarian interventions targeting children in conflict related emergencies. In particular, it notes the tendency of relief programmes to focus on "spectacular" groups of children (orphans, child combatants and refugees) at the expense of larger child populations indirectly affected by conflict. This relief bias is attributed to an inappropriate 'apocalypse model' of conflict which sees relief interventions only as repair. The bias also lies in a mistakenly universalist model of childhood and a medical paradigm which pathologizes children's experience in conflict and characterizes children as passive victims rather than active survivors. The paper argues for greater recognition of the wider social experience of children in conflict, and for relief practice which takes account of childhood resilience and children's different roles and capacities in coping with conflict. Appropriate interventions must engage with the wide variety of indigenous coping mechanisms involving children and not simply replicate a standard package of relief interventions in every emergency, based on simplistic and universalist interpretations of children's experience of conflict. 相似文献
For nearly a century researchers have investigated the uptake and utilization of dissolved organic matter (DOM) by marine
invertebrates, but its contribution to their growth, reproduction, and survival remains unclear. Here, the benefit of DOM
uptake was assessed for the marine bryozoan Bugula neritina (Linnaeus 1758) through performance comparisons of individuals in the presence and absence of DOM. The experiments were performed
using B. neritina collected from floating docks in Beaufort, NC, USA from July to September 2004. Seawater was subjected to ultraviolet irradiation
to reduce naturally occurring DOM, and then enriched with either 1 μM of palmitic acid or a mixture containing 1 μM each of
glucose, alanine, aspartic acid and glycine. Larvae in DOM-enriched and DOM-reduced treatments were sampled and induced to
metamorphose following 1, 6, 12, and 24 h of continuous swimming at 25°C. Sampled larvae were assessed for initiation of metamorphosis,
completion of metamorphosis, and ancestrular lophophore size to determine the extent to which energy acquired from DOM uptake
could offset the metabolic costs of prolonged larval swimming. DOM treatment had no significant effect on initiation of metamorphosis,
but did have a significant effect on completion of metamorphosis and lophophore size. Larvae swimming in DOM-enriched treatments
for 24 h experienced a 20% increase in metamorphic completion rate, compared to larvae swimming for 24 h in the DOM-reduced
treatment. In addition, larvae in the amino acid and sugar mixture for 24 h had a significantly larger lophophore surface
area and volume (23 and 31%, respectively), compared to larvae in DOM-depleted seawater. To ensure that the increases in performance
found in larvae with access to DOM were not due to a decrease in metabolic activity, the respiration rates for these larvae
were compared to those of larvae in DOM-depleted seawater. There were no significant differences between these treatments,
indicating that the increases in performance were due to the energy acquired from DOM. These results clearly show that for
B. neritina, DOM uptake results in increased metamorphic success and in the size of the feeding apparatus following an extended larval
swimming duration. 相似文献
Hatching asynchrony in avian species leads to age and size differences between nestlings within a brood, handicapping last-hatched chicks in the sibling rivalry. Starvation due to this competitive disadvantage has been regarded as the primary cause of an increase in mortality with hatching order. However, for gulls it has also been suggested that disease is the cause of mortality for last-hatched chicks, possibly through reduced immunocompetence and thereby an enhanced susceptibility to infection. In addition, the male-biased mortality reported for several gull species may be related to a higher vulnerability to diseases in males compared to females. To determine the potential influence of the immune system on these mortality patterns, we investigated the T-cell-mediated immunity (CMI) of black-headed gull chicks in relation to hatching order and sex. We found a significant decrease in the CMI with hatching order. This result may be causally related to systematic changes in maternal yolk steroids and carotenoids within the laying sequence. For second-laid eggs, male CMI was significantly lower than female CMI. This is possibly linked to higher plasma levels of testosterone in male embryos which might have an immunosuppressive effect. If so, this effect is masked in eggs of either high (first egg) or low (last egg) quality. Chicks with low CMI showed enhanced mortality rates. Thus the differences in immune response are likely to contribute to the observed mortality patterns. However, hatching order significantly affected mortality independently of CMI, suggesting that competitive disadvantage due to hatching asynchrony is also important.Communicated by M. Webster 相似文献
To understand how extraction of different energy sources impacts water resources requires assessment of how water chemistry has changed in comparison with the background values of pristine streams. With such understanding, we can develop better water quality standards and ecological interpretations. However, determination of pristine background chemistry is difficult in areas with heavy human impact. To learn to do this, we compiled a master dataset of sulfate and barium concentrations ([SO4], [Ba]) in Pennsylvania (PA, USA) streams from publically available sources. These elements were chosen because they can represent contamination related to oil/gas and coal, respectively. We applied changepoint analysis (i.e., likelihood ratio test) to identify pristine streams, which we defined as streams with a low variability in concentrations as measured over years. From these pristine streams, we estimated the baseline concentrations for major bedrock types in PA. Overall, we found that 48,471 data values are available for [SO4] from 1904 to 2014 and 3243 data for [Ba] from 1963 to 2014. Statewide [SO4] baseline was estimated to be 15.8 ± 9.6 mg/L, but values range from 12.4 to 26.7 mg/L for different bedrock types. The statewide [Ba] baseline is 27.7 ± 10.6 µg/L and values range from 25.8 to 38.7 µg/L. Results show that most increases in [SO4] from the baseline occurred in areas with intensive coal mining activities, confirming previous studies. Sulfate inputs from acid rain were also documented. Slight increases in [Ba] since 2007 and higher [Ba] in areas with higher densities of gas wells when compared to other areas could document impacts from shale gas development, the prevalence of basin brines, or decreases in acid rain and its coupled effects on [Ba] related to barite solubility. The largest impacts on PA stream [Ba] and [SO4] are related to releases from coal mining or burning rather than oil and gas development.
Ash deposition is still an unresolved problem when retrofitting existing air-fired coal power plants to oxy-fuel combustion. Experimental data are quite necessary for mechanism validation and model development. This work was designed to obtain laboratory combustor data on ash and deposits from oxy-coal combustion, and to explore the effects of oxy-firing on their formation. Two bituminous coals (Utah coal and Illinois coal) and one sub-bituminous coal (PRB coal) were burned on a down-fired combustor under both oxy- and air-firing. Two oxy-fired cases, i.e., 27 vol% O2/73 vol% CO2 and 32 vol% O2/68 vol% CO2, were selected to match the radiation flux and the adiabatic flame temperature of air combustion, respectively. Once-through CO2 was used to simulate fully cleaned recycled flue gas. The flue gas excess oxygen was fixed at 3 vol%. For each case, both size-segregated fly ash and bulk fly ash samples were obtained. Simultaneously, ash deposits were collected on an especially designed un-cooled deposition probe. Ash particle size distributions and chemical composition of all samples were characterized. Data showed that oxy-firing had insignificant impacts on the tri-modal ash particle size distributions and composition size distributions in the size range studied. Bulk ash compositions also showed no significant differences between oxy- and air-firing, except for slightly higher sulfur contents in some oxy-fired ashes. The oxy-fired deposits were thicker than those from air-firing, suggesting enhanced ash deposition rates in oxy-firing. Oxy-firing also had apparent impacts on the deposit composition, especially for those components (e.g., CaO, Fe2O3, SO3, etc.) that could contribute significantly to ash deposition. Based on these results, aerodynamic changes in gas flow and changes in combustion temperature seemed more important than chemical changes of ash particles in determining deposit behavior during oxy-coal combustion. 相似文献