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51.
Fungi are undoubtedly important for ecosystem functioning; however, they have been omitted or given scant attention in most biodiversity policy documents, management plans, and formal conservation schedules throughout the world. This oversight may be due to a general lack of awareness in the scientific community and compounded by a scarcity of mycology‐associated curricula at the tertiary level and a lack of mycologists in research institutions. Although molecular techniques advance the systematic cataloging of fungi and facilitate insights into fungal communities, the scarcity of professional mycologists in the environmental sciences hampers conservation efforts. Conversely, citizen science initiatives are making significant contributions to the mycology discipline by increasing awareness and extending the scope of fungal surveys. Future research by professional and amateur mycologists into the distribution of fungi and their function in ecosystems will help identify wider and more effective conservation goals.  相似文献   
52.
We used detailed time-budget observations, mark-resight data, and doubly labeled water estimates of energy expenditure to test whether energy spent on courtship display by male frigatebirds functions as a sexually selected handicap signal. During a 2-day period of time budget observations, males displayed on average 29.5% of the time (range 0–100% for 15 different males), and this value was correlated with an index of season-long display effort. Season-long display effort was strongly predictive of pairing success. Average field metabolic rate (FMR) during the 2-day time budget period was 676.5 kJ/day (range 464.8–1035.0), substantially lower than the mass-specific FMR predicted from studies of other seabirds during incubation or chick-rearing. Despite a low overall FMR, display effort could function as an energetic handicap, either if FMR correlates positively with the amount of courtship performed or if high-quality males display at a high rate because they pay a lower energy cost per unit of display than do low-quality males. We found no relationship between FMR and display rate, despite good power for doing so. We also did not find a significant difference in energy spent divided by courtship time for males that were or were not chosen by females (inferred to be high- and low-quality males, respectively), though the medians differed in the predicted direction (preferred males having lower relative costs than non-preferred males) and the confidence interval on the difference between groups was very wide. Thus, we found evidence that male courtship effort is predictive of pairing success, we rejected one mechanism by which energetic cost of display could function as a handicap, and our test of the alternate energetic handicap mechanism was equivocal.  相似文献   
53.
This paper introduces a new reversible-flow design for a continuously stirred reactor used to study sorption mass transfer in soil and solvent systems. The stirred reactor has potential advantages over conventional packed column or batch reactors because it isolates intraparticle sorption rate limitations from advective-dispersive transport, yet allows changes to flux through the reactor for analysis of sorption kinetics under dynamic conditions. Previously, stirred reactors have often failed due to clogging of sediment on the effluent frit. The reverse-flow backwashing design allows longer life and higher confidence in maintaining mixed conditions than previous designs. Mass transfer 'rate coefficients estimated from stirred and column experiments are compared; both techniques produced results consistent with a published correlation. The data also show that fitted sorption mass transfer coefficients can be strongly dependent on the choice of equilibrium partition coefficient (i.e. batch or first-moment derived values), and that the conventional two-site sorption kinetics model fails to accurately predict sorption mass transfer in the presence of changing solvent velocity through the reactor.  相似文献   
54.
The desorption kinetics of in situ chlorobenzenes (dichlorobenzenes, pentachlorobenzene and hexachlorobenzene) and 2,4,4-trichlorobiphenyl (PCB-28) were measured with a gas-purge technique for river Rhine suspended matter sampled in Lobith, The Netherlands. This suspended matter is the main source of sediment accumulation in lake Ketelmeer. In lake Ketelmeer sediment earlier observations showed that slow and very slow fractions dominate the desorption profile.

For the river Rhine suspended matter, only for PCB-28 a fast desorbing fraction of around 1.6% could be detected. The observed rate constants were on the average 0.2 h−1 for fast desorption, 0.004 h−1 for slow desorption, and 0.00022 h−1 for very slow desorption. These values are in agreement with previous findings for the sediment from lake Ketelmeer and with available literature data on fast, slow, and very slow desorption kinetics.

The results from this study show the similarity of desorption profiles between river Rhine suspended matter, and the top layer sediment from lake Ketelmeer. This indicates that slow and very slow fractions are already present in material forming the top layer of lake Ketelmeer, and were not formed after deposition of this material in the lake. The absence of detectable fast fractions for most compounds could be caused by the absence of recent pollution of the suspended matter. But, the observations may also be explained by a rapid disappearance of compounds from the fast fraction due to a combination of a high affinity of very slow sites for these compounds, and their relatively high volatility.  相似文献   

55.
为了分析汞在大气中的化学行为,在一个化学模式中加入汞的气相、气液平衡和液相反应,模拟大气汞及其化合物的演变规律,并分析了气象因子(云、光解率、温度)和化学因子(气态O3、H2O2、HO2、OH和气态零价汞Hg0(g))的初始体积分数对各形态汞及其化合物浓度和Hg0(g)转化率的影响.模拟结果表明,在中等大气污染条件下,Hg0(g)的每小时平均转化率为2.91%.敏感性试验结果表明,云量、光解率、温度、O3和Hg0(g)的初始体积分数对不同形态汞的影响较为显著.云量的增加、光解率的增加、臭氧初始体积分数的升高,各形态汞的平衡时间缩短,除气态氧化汞和一价汞离子外,其他形态汞的平衡浓度均会降低,Hg0(g)的转化率增加.温度增加将抑制Hg0(g)的转化.Hg0(g)的初始体积分数增加,各形态汞的浓度升高,但其平均转化率没有显著变化.不同因子对汞化学过程的相对作用对区域或全球大气汞的环境模拟具有指导意义.  相似文献   
56.
由于我国生态旅游发展中出现了较严重的泛化问题,不少学者把生态旅游分成了严格意义的生态旅游与一般意义的生态旅游,深层生态旅游与浅层生态旅游,大众化生态旅游与小众型生态旅游等。笔者更愿意把严格意义的生态旅游、深层生态旅游和小众型生态旅游归纳为体验式生态旅游,并从体验旅游的视角对生态旅游进行再认识,尝试对体验式生态旅游进行分析和界定。  相似文献   
57.
This Translations contribution presents the 10th issue of the series Frei.Räume (in English: Free spaces), edited by the German Feminist Organisation of (female) Planners and Architects (FOPA) in 1998. The issue was titled “New roads – new goals. Positions of feminist planning” and reflected the contemporary discussions on the state of the art of feminism, gender and planning. While progress was recognized, many authors felt uncomfortable with the ways that feminist concerns had been implemented into planning, and they were looking for ways forward. Among the authors were the most important protagonists of the debates at the time. Looking at the issue today, it becomes clear that many concerns are as up to date as they were in the late 1990s, although circumstances have changed. The paper argues that it is worthwhile to pay attention to these feminist debates in order to develop future strategies for feminism in planning.  相似文献   
58.
ABSTRACT: The Caloosahatchee River has two major sources of freshwater one from its watershed and the other via an artificial connection to Lake Okeechobee. The contribution of each source to the freshwater discharge reaching the downstream estuary varies and either may dominate. Routine monitoring data were analyzed to determine the effects of total river discharge and source of discharge (river basin, lake) on water quality in the downstream estuary. Parameters examined were: color, total suspended solids, light attenuation, chlorophyll a, and total and dissolved inorganic nitrogen and phosphorus. In general, the concentrations of color, and total and dissolved inorganic nitrogen increased, and total suspended solids decreased, as total discharge increased. When the river basin was the major source, the concentrations of nutrients (excepting ammonia) and color in the estuary were relatively higher than when the lake was the major source. Light attenuation was greater when the river basin dominated freshwater discharge to the estuary. The analysis indicates that water quality in the downstream estuary changes as a function of both total discharge and source of discharge. Relative to discharge from the river basin, releases from Lake Okeechobee do not detectably increase concentrations of nutrients, color, or TSS in the estuary.  相似文献   
59.
A volume of sand containing coal tar creosote was emplaced below the water table at CFB Borden to investigate natural attenuation processes for complex biodegradable mixtures. Coal tar creosote is a mixture of more than 200 polycyclic aromatic hydrocarbons, heterocyclic compounds and phenolic compounds. A representative group of seven compounds was selected for detailed study: phenol, m-xylene, naphthalene, phenanthrene, 1-methylnaphthalene, dibenzofuran and carbazole. Movement of groundwater through the source led to the development of a dissolved organic plume, which was studied over a 4-year period. Qualitative plume observations and mass balance calculations indicated two key conclusions: (1) compounds from the same source can display distinctly different patterns of plume development and (2) mass transformation was a major influence on plume behaviour for all observed compounds.  相似文献   
60.
北京市空气污染物对呼吸系统疾病门诊人数的影响   总被引:4,自引:0,他引:4       下载免费PDF全文
为评价北京市大气污染对居民呼吸系统疾病门诊人数的影响,采用时间序列半参广义相加模型(GAM),在控制了长期趋势、“星期几效应”及气象因素的影响后,分析2009~2011年北京市空气污染物与呼吸系统疾病门诊人数的暴露-反应关系,并按性别和年龄层建立模型.结果表明,3种污染物有一定的滞后效应,PM10在滞后0~3d(avg03)或0~5d(avg05)的移动平均值,SO2和NO2均在滞后0~2d(avg02)的移动平均值使呼吸系统疾病门诊人数的增加百分比(PI%)值达到最大,其中PM10、SO2和NO2浓度每增加10μg/m3,对应的呼吸系统疾病全人群的PI%分别为1.72%、1.34%和2.57%.年龄365岁的老年人群对北京市空气污染物最为敏感,其次为年龄£14岁的人群;空气污染对女性的影响较男性明显.  相似文献   
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