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61.
M.Greg Faulkner James L. DuBard John P. Gooch Jack R. McDonald James H. Abbott Dennis C. Drehmel 《Environment international》1981,6(1-6)
The advantages and disadvantages of several possible control strategies for particulate emissions from vehicular diesel exhaust are discussed. The evaluation of the potential usefulness of the various control strategies is based on available data concerning the mass loading and particle size distribution and on anticipated control standards. Several studies have been made on devices for removing particulate emissions from vehicular diesel exhaust. These studies, which include the techniques of filtration, wet scrubbers, and electrostatic precipitation, are summarized. A comparison of the various control devices is made based on such factors as size, efficiency, and maintenance requirements. 相似文献
62.
Previous projects specifically aimed at performing radiological assessments in the vicinity of North Wales, investigating the presence and transfer of radionuclides from sea to land, were in 1986 and 1989. Since then, changes have occurred in the radioactive discharges from the British Nuclear Group Sellafield site. Annual discharges of (137)Cs, (238)Pu, (239,340)Pu and (241)Am have decreased markedly whereas, up until recent years, discharges of (99)Tc have increased. It is therefore desirable to quantify current transfer processes of radionuclides in the North Wales region and thus provide an update on 15-year-old studies. A field campaign was conducted collecting soil samples from 10 inland transects and air particulates on air filters from three High Volume Air Samplers, along the northern coast of Wales at Amlwch, Bangor Pier and Flint. Complementary field data relating to external gamma dose rates were collected at the soil sites. The field data generated for (137)Cs, (238)Pu, (239,340)Pu and (241)Am were consistent with what had been reported 15 years previously. Therefore, there has been no increase in the supply of these Sellafield-derived radionuclides to the terrestrial environment of the North Wales coast. The (99)Tc data in sediments were consistent with reported values within annual monitoring programmes, however, a relatively high activity concentration was measured in one sediment sample. This site was further investigated to determine the reason why such a high value was found. At present there is no clear evidence as to why this elevated concentration should be present, but the role of seaweed and its capacity in accumulating (99)Tc and transferring it to sediment is of interest. The analysis of the field samples for (99)Tc, (137)Cs, (238)Pu, (239,240)Pu and (241)Am has provided a data set that can be used for the modelling of the transfer of anthropogenic radionuclides from sea to land and its subsequent radiological implications and is reported in an accompanying paper. 相似文献
63.
Application of radioisotope sediment dating models to lakes subjected to large anthropogenic sediment inputs can be problematic. As a result of copper mining activities, Torch Lake received large volumes of sediment, the characteristics of which were dramatically different from those of the native sediment. Commonly used dating models (CIC-CSR, CRS) were applied to Torch Lake, but assumptions of these methods are violated, rendering sediment geochronologies inaccurate. A modification was made to the CRS model, utilizing a distinct horizon separating mining from post-mining sediment to differentiate between two focusing regimes. (210)Pb inventories in post-mining sediment were adjusted to correspond to those in mining-era sediment, and a sediment geochronology was established and verified using independent markers in (137)Cs accumulation profiles and core X-rays. 相似文献
64.
65.
Robert McDonald 《国际发展与全球生态学杂志》2013,20(6):445-447
There has been considerable debate about how best to define sustainable development. In this commentary, I argue that Amartya Sen's concept of 'development as freedom' is the appropriate theoretical framework for understanding sustainable development. Environmentalists should consider defining their goal as 'sustainable development as freedom,' the achievement of the greatest possible level of freedom without restricting the access of future generations to these same freedoms. The adoption of this framework has implications for the work of environmental NGOs, which are briefly discussed. 相似文献
66.
We developed quantitative PCR (qPCR) assays to distinguish each of the four clades (A–D) of dinoflagellate endosymbionts (genus Symbiodinium) commonly found in Caribbean corals. We applied these primer sets, which target portions of the multi-copy ribosomal DNA (rDNA) gene family, to assess the presence/absence of symbionts in clade D (as indicated by the detection of clade D DNA). We detected these symbionts in five of six Caribbean host species/genera (21% of samples analyzed, N = 10 of 47 colonies), from which clade D had rarely or never been observed. This suggests that Symbiodinium in clade D are present in a higher diversity of coral species than previously thought. This qPCR-based approach can improve our understanding of the total microbial diversity associated with corals, particularly in hosts thought to be relatively specific, and has many other potential applications for studies of coral reef ecology and conservation. 相似文献
67.
David B. McDonald 《Behavioral ecology and sociobiology》2009,63(7):1029-1034
I use 10 years of data from a long-term study of lek-mating long-tailed manakins to relate the social network among males
to their spatial and genetic structure. Previously, I showed that the network connectivity of young males predicts their future
success. Here, I ask whether kinship might shape the organization of this “young-boy network”. Not surprisingly, males that
were more socially distant (linked by longer network paths) were affiliated with perch zones (lek arenas) that were further
apart. Relatedness (r) among males within the network decreased as social distance increased, as might be expected under kin selection. Nevertheless,
any role for indirect inclusive fitness benefits is refuted by the slightly negative mean relatedness among males at all social
distances within the network (overall mean r = −0.06). That is, relatedness ranged from slightly negative (−0.04) to more negative (−0.2). In contrast, relatedness in
dyads for which at least one of the males was outside the social network (involving at least one blood-sampled male not documented
to have interacted with other banded males) was slightly above the random expectation (mean r = 0.05). The slight variations around r = 0 among males of different categories likely reflect dispersal dynamics, rather than any influence of kinship on social
organization. Relatedness did not covary with the age difference between males. These results, together with previous results
for lack of relatedness between alpha and beta male partners, refute any role for kin selection in the evolution of cooperative
display in this lek-mating system.
This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau,
and R. James). 相似文献
68.
Virender K. Sharma Xin Yu Thomas J. McDonald Chetan Jinadatha Dionysios D. Dionysiou Mingbao Feng 《Frontiers of Environmental Science & Engineering》2019,13(3):37
69.
As a result of 210Po's previously identified association with sulphur-rich proteins, metallothioneins could have a significant effect on the
behaviour and fate of 210Po in molluscs. Starved control and cadmium-exposed mussels, Mytilus edulis, were fed 210Po-labelled algae (Isochrysis galbana) for 5 d and then allowed to depurate in clean sea water. Cadmium-exposed M. edulis accumulated less 210Po in the digestive gland and the remainder of the tissue than control mussels, although this was due to a decrease in tissue
weight. More than 40% of 210Po was identified as being associated with high molecular weight and heat-treated cytosol proteins in M. edulis. Mussels in a starved state are known to recycle as much as 90% of their amino acids. It is proposed that 210Po associated with these and other proteins is recycled, explaining why no significant loss of 210Po was observed from the remainder of the tissue in either control or Cd-exposed mussels. Cadmium-induced metallothioneins
had no effect on the distribution of 210Po in M. edulis; <5% associated with the cytosolic fraction was considered to principally contain metallothioneins. It is suggested that
210Po's apparent relationship with metallothioneins is coincidental rather than connected with its role in the regulation of
metals.
Received: 30 March 1998 / Accepted: 3 August 1998 相似文献
70.
To date seagrass monitoring has involved the removal of seagrass from its environment. In fragile or highly disturbed systems, monitoring using destructive techniques may interfere with the environment or add to the burden of disturbance. Video photography is a form of non-destructive monitoring that does not require the removal of seagrass or interference with the environment and has the potential to be a valuable tool in monitoring seagrass systems. This study investigated the efficacy of video photography as a tool for detecting change in seagrass cover, using the temperate Australian species Amphibolis antarctica (Labill.) Sonder ex Aschers. Using visual and random point estimates of seagrass cover from video footage, it was possible to determine the minimum sample size (number of random video frames) needed to detect change in seagrass cover, the minimum detectable change in cover and the probability of the monitoring design committing a Type II error. Video footage was examined at three scales: transects (m apart), sites (km apart) and regions (tens of km apart). Using visual and random point estimation techniques, a minimum sample size of ten quadrats per transect was required to detect change in uniform and variable seagrass cover. With ten quadrats it was possible to identify a minimum detectable change in cover of 15% for uniform and 30% for variable seagrass cover. Power analysis was used to determine the probability of committing a Type II error from the data. Region level data had low power, corresponding to a high risk of committing a Type II error. Site and transect level data had high power corresponding to a low risk of committing a Type II error. Based on this study's data, managers using video to monitor for change in seagrass cover are advised to use data from the smaller scale, for example, site and transect level data. By using data from the smaller scale, managers will have a low risk of incorrectly concluding there has not been a disturbance when one has actually occurred. 相似文献