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121.
Birds migrating along coastlines may be at increased risk if displacement occurs toward open-ocean. Eastern North America
experiences prevailing northwesterly winds during autumn, which could compel some migrants to drift eastward. Therefore, migrants
at stop-over sites along this route may be a mixture of on- and off-course individuals. We assessed whether orientation behavior
of juvenile yellow-rumped warblers (Dendroica coronata) captured at a stop-over site in southern Nova Scotia was related to where they originated from (i.e., likely on/off-course).
We hypothesized three scenarios after displacement: 1) continued orientation in the migratory direction selected before displacement,
2) orientation from the new location toward the previous destination, or 3) correction to regain the original pathway. Using
stable isotopes, we determined that stop-over migrants originated from nearby areas (and assumed on-course) and as far away
as western Hudson Bay, over 1,600 km northwest (and assumed off-course) of the site. We used video-based orientation registration
cages to determine an individuals’ migratory orientation. Because numerous factors influence migratory orientation (e.g.,
fuel reserves, celestial cues), we simultaneously assessed the influence of body condition and cloud cover, in addition to
geographic origin, on orientation behavior. Individuals that originated closer to the site tended to orient more southwesterly.
Orientation directions became increasingly more west-northwesterly the further away an individual originated from the site
(i.e., the more likely it was to have been displaced). The result is most consistent with scenario three: individuals from
northwest origins likely respond to easterly displacement by orienting westerly to reestablish their previous migratory route. 相似文献
122.
An Endangered Longhorn Beetle Associated with Old Oaks and Its Possible Role as an Ecosystem Engineer 总被引:2,自引:0,他引:2
Abstract: For more than 10 years, ecologists have been discussing the concept of ecosystem engineering (i.e., nontrophic interactions of an organism that alters the physical state of its environment and affects other species). In conservation biology, the functional role of species is of interest because persistence of some species may be necessary for maintaining an entire assemblage with many threatened species. The great capricorn ( Cerambyx cerdo ), an endangered beetle listed in the European Union's Habitats Directive, has suffered a dramatic decline in the number of populations and in population sizes in Central Europe over the last century. The damage caused by C. cerdo larvae on sound oak trees has considerable effects on the physiological characteristics of these trees. We investigated the impacts of these effects on the species richness and heterogeneity of the saproxylic beetle assemblage on oaks. We compared the catches made with flight interception traps on 10 oaks colonized and 10 oaks uncolonized by C. cerdo in a study area in Lower Saxony (Germany). Our results revealed a significantly more species-rich assemblage on the trees colonized by C. cerdo . Colonized trees also harbored more red-listed beetle species. Our results suggest that an endangered beetle species can alter its own habitat to create favorable habitat conditions for other threatened beetle species. Efforts to preserve C. cerdo therefore have a positive effect on an entire assemblage of insects, including other highly endangered species. On the basis of the impact C. cerdo seems to have on the saproxylic beetle assemblage, reintroductions might be considered in regions where the species has become extinct. 相似文献
123.
A cellulose solvent system based on lithium chloride (LiCl) in N-methyl-2-pyrrolidinone (NMP) was used to assess the merits of partial dissolutions of coarsely ground wood samples. Alkaline Copper Quaternary (ACQ)-treated pine wood was of particular interest for treatment given the potential to generate a copper-rich stream apart from solid and/or liquid lignocellulosic feedstocks. Treatment with NMP alone gave yields of soluble materials that were higher than typical extractives contents thereby suggesting a limited degree of wood dissolution. Inclusion of LiCl, which disrupts hydrogen bonding, gave lower wood residue recoveries (i.e., higher dissolution) with higher LiCl concentration. Lower wood residue recoveries coincided with lower Klason lignin and hemicellulose-derived sugar contents in the wood residues. After treatment with 8% LiCl in NMP, subsequent filtration afforded 34% of the ACQ-treated sapwood as a wood residue retaining only 2% of the original copper. Pouring the filtrate over an excess of water resulted in the recovery of 30% of the solids and 50% of the copper together as a copper-enriched lignocellulosic precipitate. Results demonstrate a solvent system showing potential as a means to separate heavy metals from preservative-treated wood and to recover lignocellulosic feedstocks that may be suitable for use in a biorefinery. 相似文献
124.
木粉/壳聚糖接枝丙烯酸-丙烯酰胺吸附树脂对二元重金属离子溶液中Pb2+的吸附 总被引:1,自引:0,他引:1
采用自制木粉/壳聚糖接枝丙烯酸-丙烯酰胺吸附树脂R1、R2、R3对二元金属离子Cu2 +/pb2和Zn2+/pb2+溶液中的吸附性能进行了较系统考察.pb2+离子溶液中存在竞争离子Cu2+、Zn2+时,随竞争离子浓度增加,3种吸附树脂R1、R2、R3对pb2+的吸附量明显下降,而竞争离子吸附量显著增加.二元溶液中各金属离子浓度相同时,3种树脂对竞争离子Cu2+、Zn2+的吸附量大于对pb2+的吸附量;各溶液中分别加入NaCl及NaNO3、尿素后,对pb2+离子的吸附量下降迅速.随吸附树脂用量增加,竞争离子Cu2+、Zn2+的吸附量逐渐减小,pb2+的吸附量在吸附树脂用量0.10 g/L(Zn2 +/pb2+溶液)或0.15 g/L(Cu2+/pb2+溶液)时出现最大值.溶液pH值对树脂吸附性能有显著影响.3.0<pH<5.O时,3种树脂对竞争离子和pb2+的吸附量快速增大;5< pH <9时,树脂对竞争离子和pb2+的吸附量基本不变;9<pH<ll时,树脂对pb2+的吸附量减小,而对竞争离子的吸附量或增大或减小. 相似文献
125.
废旧聚乙烯复合材料的制备与性能研究 总被引:1,自引:0,他引:1
介绍了废旧聚乙烯复合材料的制备与性能。以废旧聚乙烯为原材料,通过与超细白炭黑进行纳米复合,制备高性能纳米复合材料;利用木粉、竹粉、稻糠等植物纤维与其进行木塑复合,制备环保型木塑复合材料;重点研究了多单体接枝共聚物在复合材料中的界面改性作用。 相似文献
126.
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128.
PAHs were sampled in ten homes in the Makwanpur region, Nepal. SPMDs and moss bags (Sphagnum girgensohnii) were used as passive samplers. Soot particles on the SPMD surfaces were also analyzed for PAHs. The overall PAH concentrations in SPMDs were significantly higher than those in moss bags. Total PAH mean concentrations of ten houses were 535μg/g lipid for SPMDs and 7.2 μg/g moss (dw) for moss bags. Ratios of phenanthrene/anthracene in indoor SPMDs and particulate matter varied from 2.9 to 3.5 and ratios of fluoranthene/pyrene varied from 1.1 to 1.4. The values for moss bags were respectively 1.7–3.6 and 0.8–2.4. These ratios indicate that the PAHs are from combustion origin. The PAH concentrations in ambient air were estimated as B(a)P TEQs and they were 17–64 times higher than acceptable limit for Finnish community air. Based on PAH levels in the gas phase (SPMD) we may expect PAHs to have an impact on respiratory disease prevalence in Nepalese villages. Both of the sampling methods were feasible in the difficult conditions under which the study was performed. 相似文献
129.
Wood charcoal production provides affordable energy in many developing countries and has substantially contributed to the economy through the provision of rural incomes. In several countries, charcoal production leads to overexploitation of forests due to inefficiencies in processing. This study was undertaken in central Laos to (1) examine and document traditional charcoal production systems; (2) investigate the production capacity, recovery efficiencies and economic gains of existing traditional charcoal production methods; (3) characterize the chemical properties of wood charcoal and investigate the potential for soil restoration and (4) investigate local charcoal producers' perception on forest degradation and their species preferences. Through a socio-economic survey, a cost-based method for economic valuation was undertaken on a range of charcoal production methods currently being used. Laboratory chemical analyses were performed on wood charcoal samples. Results indicated that the traditional mud charcoal mound was used by the majority (82%) of charcoal producers. Total charcoal production per production cycle varied between 400 (produced from 2.7 m3 of wood) and 1600 kg (produced from 18 m3 of wood), with a mean of 938 kg (±120) for traditional mud charcoal mounds. The volume of the traditional mud charcoal mounds correlated positively and significantly with total charcoal production (R 2 = 0.45, p?=?0.03), whereas correlated negatively and significantly with the recovery efficiency (R 2 = 0.58, p?=?0.01). On average, the local producers receive a total net benefit of 457,272 Lao kip (USD 57.2) in 17 days. We also identified a rice husk mound method of charcoal production, which may not encourage further deforestation while producing rice husk biochar that can be used for soil restoration. Furthermore, we found that there are significant differences (p < 0.05) between the sampled wood charcoals in chemical properties, indicating that the potential of using wood charcoal for the restoration of degraded soils varies from charcoal to charcoal. 相似文献
130.
农村室内薪柴燃烧的颗粒物和炭黑排放因子 总被引:3,自引:0,他引:3
室内薪柴燃烧是大气污染的重要来源,其排放的污染物对气候变化和人体健康都有很大影响。对该来源排放量的可靠估算是进行排放效应分析和合理控制的重要前提,而估算的可靠性主要取决于燃料消耗量和排放因子的准确性。目前,我国针对农村柴灶薪柴燃烧颗粒物排放因子的测定数据很少,变异很大,不足以支持可靠的排放清单估算。测定了9种薪柴(枫桦、兰考泡桐、黑杨、大叶风杨、楝树、枣树、柿树、桑树和桃树)在中国北方典型农村炉灶中燃烧产生的颗粒物(PM)、有机碳(OC)和元素碳(EC)的排放因子。受燃料种类、性质和燃烧条件的影响,测得的排放因子差别较大。9种薪柴各自的PM、EC和OC的排放因子变化范围分别为(0.74±0.13)~(6.23±1.47)g.kg-1,(0.10±0.06)~(0.97±0.28)g.kg-1和(0.14±0.03)~(3.81±0.92)g.kg-1(以干质量计)。全部薪柴的PM、EC和OC的排放因子均值和标准差分别为(2.58±2.15)、(0.29±0.31)和(0.98±1.24)g.kg-1。室内薪柴燃烧PM、EC和OC排放因子之间呈显著的相关性关系。各种薪柴燃烧排放的颗粒物粒径分布相似,均以细颗粒物为主,PM2.1占PM10总质量的90%以上。此外,除EC排放因子外,薪柴燃烧的PM和OC排放因子与校正燃烧效率显著负相关(P<0.05)。细颗粒物组分PM2.1与校正燃烧效率显著负相关(P<0.05),与燃料含水量显著正相关(P<0.05)。 相似文献