A multispecies test of source–sink indicators to prioritize habitat for declining populations

For species at risk of decline or extinction in source–sink systems, sources are an obvious target for habitat protection actions. However, the way in which source habitats are identified and prioritized can reduce the effectiveness of conservation actions. Although sources and sinks are conceptually defined using both demographic and movement criteria, simplifications are often required in systems with limited data. To assess the conservation outcomes of alternative source metrics and resulting prioritizations, we simulated population dynamics and extinction risk for 3 endangered species. Using empirically based habitat population models, we linked habitat maps with measured site‐ or habitat‐specific demographic conditions, movement abilities, and behaviors. We calculated source–sink metrics over a range of periods of data collection and prioritized consistently high‐output sources for conservation. We then tested whether prioritized patches identified the habitats that most affected persistence by removing them and measuring the population response. Conservation decisions based on different source–sink metrics and durations of data collection affected species persistence. Shorter time series obscured the ability of metrics to identify influential habitats, particularly in temporally variable and slowly declining populations. Data‐rich source–sink metrics that included both demography and movement information did not always identify the habitats with the greatest influence on extinction risk. In some declining populations, patch abundance better predicted influential habitats for short‐term regional persistence. Because source–sink metrics (i.e., births minus deaths; births and immigrations minus deaths and emigration) describe net population conditions and cancel out gross population counts, they may not adequately identify influential habitats in declining populations. For many nonequilibrium populations, new metrics that maintain the counts of individual births, deaths, and movement may provide additional insight into habitats that most influence persistence.     

海藻酸钠固定化Fe-Cu双金属去除Cr(Ⅵ)的作用机制

通过运用海藻酸钠(SA)固定化Fe-Cu双金属(SAB)来克服Fe0-PRB利用率低、易板结、堵塞的缺陷.结果表明,SA和Fe-Cu双金属的运用能极大地提高Fe0的利用率,SA的运用可以使Fe-Cu双金属以较低的镀铜量获得较高的Cr(Ⅵ)去除率,SAB镀铜0.9%(SAB0.9)为最佳的填料.FEI电镜扫描结果表明,SA跟2价金属阳离子Ca2+交联形成孔隙结构,为双金属的附着提供了大量的吸附点位,增大了金属颗粒的比表面积;场发射扫描电子显微镜(FESEM)及X-射线光电子能谱(XPS)结果表明,Cu负载于Fe0表面,呈疏松层状结构,在Fe0与Cr(Ⅵ)反应中起催化剂作用,通过自身化合态变化传递Fe0失去的电子,从而提高了Fe0的利用率.渗透系数实验结果表明,SAB0.9能控制Fe0与Cr(Ⅵ)反应产物的释放,缓解Fe0-PRB易板结、堵塞的缺陷.     

Correlating the Spatial Distribution of Atmospheric Ammonia with δ15N Values at an Ammonia Release Site

A field ammonia (NH₃) release experiment and open top chambers containing moorland monoliths continuously fumigated with NH₃ or sprayed with NH₄Cl were used to assess the potential for using 0">¹⁵N values in determining the area of influence around a point NH₃ emission source. 0">¹⁵N values are being increasingly used as environmental tracers and we tested the hypothesis that the 0">¹⁵N signal from an NH₃ emission source is observable in nearby vegetation. Using modified monitoring devices, atmospheric NH₃ concentrations were found to decrease with distance from source, with 0">¹⁵N values also reflecting this trend, producing a signal shift with changing concentration. Open top chamber studies of 0">¹⁵N values of Calluna vulgaris (L.) Hull indicated a correlation with deposition treatments in current year shoots. Analysis of Calluna shoots from the NH₃ release showed a similar trend of 0">¹⁵N enrichment. Significant linear correlations between 0">¹⁵N and percent N in plant material were found, both in the controlled conditions of the open top chambers and at the NH₃ release site, illustrating the possible use of this technique in N deposition biomonitoring.     

Kinetics of Aerobic Polymer Degradation in Soil by Means of the ASTM D 5988-96 Standard Method

The standard test method ASTM D 5988-96 for determining the degree and rate of aerobic biodegradation of plastic materials in contact with soil was applied to poly(3-hydroxybutyrate) and poly(0175l4qt13/xxlarge603.gif" alt="epsiv" align="BASELINE" BORDER="0">-caprolactone). The method proved to be reliable and supplied reproducible measurements of CO₂ production, provided potassium (instead of barium) hydroxide was used as a trapping solution. The trends of CO₂ evolution, as a function of time, observed for the degradation of polymer powders in soil are similar to those predicted by simple first order kinetics in solution. The experimental data are described by a Michaelis013;Menten type model, which accounts for the heterogeneity of the polymer-soil system. The kinetic equation deduced predicts the degradation rate to the proportional to the exposed polymer surface area.     

Mechanical Properties and Lipase-Catalyzed Biodegradation of α-Methyl, ε-Caprolactone/ ε-Caprolactone Copolymers Obtained by Chemical Modification of Poly(ε-caprolactone)

Novel (0">-caprolactone)-based copolymers of different compositions were synthesized by allowing methyl iodide to react with the polycarbanion that resulted from the action of lithium diisopropylamide on poly(0">-caprolactone) in THF at 013;70°C under argon atmosphere. The copolymers were characterized by various techniques, namely ¹H nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, x-ray diffraction and viscoelasticimetry. They were submitted to hydrolytic and lipase-catalyzed enzymatic degradation in comparison with genuine PCL. The Young modulus depended on the degree of methylation. In contrast, loss angle and glass transition temperature did not depend on this parameter. It is shown that the lipase-catalyzed degradation of methylated PCL is much slower than in the case of genuine PCL.     

Selection of (bio) indicators to assess effects of freshwater use in wetlands: a case study of s’Albufera de Mallorca, Spain

Parc Natural s0lm9uvu2/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">Albufera de Mallorca is an internationally recognised resting area for a wide array of migratory birds, and like most wetlands it has many other ecological functions and socio-economic values. In the catchment, in which the wetland is situated, expanding tourism and intensification of agriculture place much pressure on a limited amount of freshwater. The freshwater supply to the wetland decreased due to water-extraction mainly driven by intensification of agriculture in the catchment. As a result saltwater intrusion increased since 1983013;1985. This had considerable impacts on the ecological integrity of the wetland as reflected by changes in the state of the aquatic ecosystem. The distribution of submerged plants, less tolerant of salinity, declined or disappeared, while the distribution of species, known to prefer high salinity increased. As a contribution to the development of monitoring programs and management strategies that address both socio-economic and natural water demand, this article will formulate ecological criteria to assess the natural water demand by selection of (bio)indicators within the aquatic ecosystem.     

Mg improves biomass production from soybean wastewater using purple non-sulfur bacteria

Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria (PNSB). This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg^{2 0;+} under the light-anaerobic condition. Results showed that with the optimal Mg^{2 0;+} dosage of 10 0;mg/L, biomass production was improved by 70% to 3630 0;mg/L, and biomass yield also was improved by 60%. Chemical Oxygen Demand (COD) removal reached above 86% and hydraulic retention time was shortened from 96 to 72 0;hr. The mechanism analysis indicated that Mg^{2 0;+} could promote the content of bacteriochlorophyll in photosynthesis because Mg^{2 0;+} is the bacteriochlorophyll active center, and thus improved adenosine triphosphate (ATP) production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials (biomass yield) and COD removal, leading to more biomass production. With 10 0;mg/L Mg^{2 0;+}, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.     

Mechanism and kinetics of aluminum dissolution during copper sorption by acidity paddy soil in South China

Soil aggregates were prepared from a bulk soil collected from paddy soil in the Taihu Lake region and aluminum (Al) dissolution, solution pH changes during copper (Cu^{2 0;+}) sorption were investigated with static sorption and magnetic stirring. Kinetics of Cu^{2 0;+} sorption and Al dissolution were also studied by magnetic stirring method. No Al dissolution was observed until Cu^{2 0;+} sorption was greater than a certain value, which was 632, 450, 601 and 674 0;mg/kg for sand, clay, silt, and coarse silt fractions, respectively. Aluminum dissolution increased with increasing Cu^{2 0;+} sorption and decreasing solution pH. An amount of dissolved Al showed a significant positive correlation with non-specific sorption of Cu^{2 0;+} (R² 0;> 0;0.97), and it was still good under different pH values (R² 0;> 0;0.95). Copper sorption significantly decreased solution pH. The magnitude of solution pH decline increased as Cu^{2 0;+} sorption and Al dissolution increased. The sand and clay fraction had a less Al dissolution and pH drop due to the higher ferric oxide, Al oxide and organic matter contents. After sorption reaction for half an hour, the Cu^{2 0;+} sorption progress reached more than 90% while the Al dissolution progress was only 40%, and lagged behind the Cu^{2 0;+} sorption. It indicated that aluminum dissolution is associated with non-specific sorption.     

Degradation of rhodamine B by Fe(0)-based Fenton process with H2O2

Degradation of rhodamine B by Fe(0)-based Fenton process with H₂O₂ was investigated. The effects of H₂O₂ dose, Fe(0) dose, initial concentration of rhodamine B and initial pH value on the degradation of rhodamine B were examined. The results showed that the degradation and mineralization of rhodamine B occurred with low dose of H₂O₂ and Fe(0). The intermediates of rhodamine B were analyzed with UV-Vis spectrophotometry and ion chromatography and the mechanism of oxidative degradation of rhodamine B was also discussed. The reactive oxygen species (·OH) produced in Fe(0)-based Fenton process with H₂O₂ is the key to the degradation of rhodamine B by ways of N-de-ethylation, chromophore cleavage, ring-opening and mineralization.