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11.
Henrik Brumm Sue Anne Zollinger Peter J. B. Slater 《Behavioral ecology and sociobiology》2009,63(9):1387-1395
Several recent studies have tested the hypothesis that song quality in adult birds may reflect early developmental conditions,
specifically nutritional stress during the nestling period. Whilst all of these earlier studies found apparent links between
early nutritional stress and song quality, their results disagree as to which aspects of song learning or production were
affected. In this study, we attempted to reconcile these apparently inconsistent results. Our study also provides the first
assessment of song amplitude in relation to early developmental stress and as a potential cue to male quality. We used an
experimental manipulation in which the seeds on which the birds were reared were mixed with husks, making them more difficult
for the parents to obtain. Compared with controls, such chicks were lighter at fledging; they were thereafter placed on a
normal diet and had caught up by 100 days. We show that nutritional stress during the first 30 days of life reduced the birds’
accuracy of song syntax learning, resulting in poorer copies of tutor songs. Our experimental manipulations did not lead to
significant changes in song amplitude, song duration or repertoire size. Thus, individual differences observed in song performance
features probably reflect differences in current condition or motivation rather than past condition. 相似文献
12.
Yuxin Wu Roelof Versteeg Lee Slater Douglas LaBrecque 《Journal of contaminant hydrology》2009,106(3-4):131-143
Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO3 and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO3 as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO3 dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO3 forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO3 precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation. 相似文献
13.
Variation in PAH inputs and microbial community in surface sediments of Hamilton Harbour: implications to remediation and monitoring 总被引:2,自引:0,他引:2
Slater GF Cowie BR Harper N Droppo IG 《Environmental pollution (Barking, Essex : 1987)》2008,153(1):60-70
Variations in concentrations of polycyclic aromatic hydrocarbons (PAHs) and microbial community indicators were investigated in representative highly contaminated and less contaminated surface sediment sites of Hamilton Harbour. Inputs of PAH to the upper 3cm of sediments up to four times the average upper sediment concentrations were observed. Associated PAH fingerprint profiles indicated that the source was consistent with the PAH source to the industrial region of the harbour. Increased PAH loadings were associated with decreased bacterial populations as indicated by phospholipid fatty acid (PLFA) concentrations. However, relatively minor impacts on overall community composition were indicated. Porewater methane concentrations and isotopic data indicated a difference in the occurrence of methane oxidation between the two sites. This study confirms temporally limited transport of contaminants from highly impacted regions as a vector for contaminants within the harbour and the impact on microbial carbon cycling and bed stability. 相似文献
14.
Many animal signals are performed in a highly redundant manner as in some bird species where males sing several renditions of one song type before switching to another. However, differences in signal redundancy between contexts and between individuals are only poorly understood. We found that chaffinches (Fringilla coelebs) in noisier areas (i.e., close to waterfalls and torrents) sang longer bouts of the same song type before switching to a new type, suggesting that they use increased serial redundancy to get the message across in noisy conditions. This is the first evidence of a noise-dependent adjustment of signal redundancy in a songbird. In addition, we found that song types with faster trills were sung in shorter bouts suggesting that the performance of highly redundant song series is probably limited by motor constraints. Thus, in noisy environments, serial redundancy in bird song may reflect a trade-off between successful signal transmission and preventing motor fatigue. 相似文献
15.
Carbon isotope fractionation during reductive dechlorination of TCE in batch experiments with iron samples from reactive barriers 总被引:4,自引:0,他引:4
Reductive dechlorination of trichloroethene (TCE) by zero-valent iron produces a systematic enrichment of 13C in the remaining substrate that can be described using a Rayleigh model. In this study, fractionation factors for TCE dechlorination with iron samples from two permeable reactive barriers (PRBs) were established in batch experiments. Samples included original unused iron as well as material from a barrier in Belfast after almost 4 years of operation. Despite the variety of samples, carbon isotope fractionations of TCE were remarkably similar and seemed to be independent of iron origin, reaction rate, and formation of precipitates on the iron surfaces. The average enrichment factor for all experiments was -10.1 per thousand (+/- 0.4 per thousand). These results indicate that the enrichment factor provides a powerful tool to monitor the reaction progress, and thus the performance, of an iron-reactive barrier over time. The strong fractionation observed may also serve as a tool to distinguish between insufficient residence time in the wall and a possible bypassing of the wall by the plume, which should result in an unchanged isotopic signature of the TCE. Although further work is necessary to apply this stable isotope method in the field, it has potential to serve as a unique monitoring tool for PRBs based on zero-valent iron. 相似文献
16.
Anne-Michelle Slater Ole W. Pedersen 《Journal of Environmental Planning and Management》2009,52(6):797-812
This paper considers the concept of environmental justice in Scotland. It reviews the research and developments in law and policy in this area, starting with the Dynamic Earth speech in Edinburgh in 2002. It analyses the findings by grouping causes and solutions to environmental justice and identifies a particularly wide definition of the concept in Scotland. It concludes that the inclusion of social justice is a defining feature of environmental justice in Scotland; however, measures to mitigate environmental injustice are being implemented in an incremental way, with the most significant achievements being through the implementation of international obligations. 相似文献
17.
The decline in sea cucumber fisheries that serve the Asian dried seafood market has prompted an increase in global sea cucumber
aquaculture. The tropical sandfish (Holothuria scabra) has, in this context, been reared and produced with mixed success. In the Western Indian Ocean, villagers often participate
in the export fishery for sea cucumbers as a source of income. However, with a growing concern of depleted stocks introduction
of hatcheries to farm sandfish as a community livelihood and to replenish wild stocks is being promoted. This review identifies
and discusses a number of aspects that constitute constraints or implications with regard to development of sandfish farming
in the region. The conclusion is that for sandfish farming to live up to its expectations the possible impacts need to be
further studied, and that improved evaluation of ongoing projects is required. In the interim, a precautionary approach toward
new enterprise activities is suggested. 相似文献
18.
Soluble reactive phosphorus (SRP) in northwestern Ohio river water has declined over the past 20 yr in response to decreased applications of fertilizer P. Our objective was to evaluate changes in soluble P (Bray-1 P) levels in the soil over time as influenced by fertilizer P management, cultivation practice, soil properties, and landscape factors. Because soil is the intermediary between added P and SRP measured in river water, we examined the relationship between fertilizer P, soluble soil P, and SRP. Using historical soil survey sample sites as a baseline for original soluble P concentrations (Por), we resampled Ap horizons to establish current levels of soluble P (Pcu). The Por baseline extended from 1953-1982 and Pcu from 1996-1998. Thirty percent of the Pcu values and 17% of the Por values were > or = 40 mg kg(-1). Log-transformed means for Pcu were significantly higher than for Por. The principal determining factors for Por were physiography, soil texture, and soil series. Current P is affected by present tillage practice and drainage class. Change in soluble P in the soil is not as responsive to fertilizer P sales as is SRP in river water. This suggests that as fertilizer P sales decline, a declining percentage of P added as fertilizer is annually dissolved and transported into the drainage system. Soluble P in soil is governed by a combination of fertilizer and tillage management, soil properties, and landscape factors interacting over time. 相似文献
19.
C Linda Slater 《Natural resources forum》1996,20(1):37-48
This analysis compares the gold mining industry investment climate in the USA to the investment climate in Australia. These two major gold producing nation's industries share many similarities; in both the USA and Australia, there is evidence of a maturing gold mining industry. Each country has experienced a dramatic increase in gold production and, more recently, greater mining of refractory ore and development of more underground operations. In the 1980s both nations experienced a pronounced rationalization trend that consolidated some gold producing operations and eliminated others. Each country commands a disproportionately large share of exploration expenditures. Land access, a major concern in the USA, has also become a critical issue in Australia as well. For all their similarities, however, the two countries have differences that are significant enough to influence mining company investment decisions. This paper explores those differences and how they may affect the future course of these nations' gold mining industries. Both effective government policy making and corporate strategic planning will occupy a major role in the future course of the two nations' gold mining industries . 相似文献
20.
Isotopic fractionation during reductive dechlorination of trichloroethene by zero-valent iron: influence of surface treatment 总被引:4,自引:0,他引:4
During reductive dechlorination of trichloroethene (TCE) by zero-valent iron, stable carbon isotopic values of residual TCE fractionate significantly and can be described by a Rayleigh model. This study investigated the effect of observed reaction rate, surface oxidation and iron type on isotopic fractionation of TCE during reductive dechlorination. Variation of observed reaction rate did not produce significant differences in isotopic fractionation in degradation experiments. However, a small influence on isotopic fractionation was observed for experiments using acid-cleaned electrolytic iron versus experiments using autoclaved electrolytic iron, acid-cleaned Peerless cast iron or autoclaved Peerless cast iron. A consistent isotopic enrichment factor of epsilon = -16.7/1000 was determined for all experiments using cast iron, and for the experiments with autoclaved electrolytic iron. Column experiments using 100% cast iron and a 28% cast iron/72% aquifer matrix mixture also resulted in an enrichment factor of -16.9/1000. The consistency in enrichment factors between batch and column systems suggests that isotopic trends observed in batch systems may be extrapolated to flowing systems such as field sites. The fact that significant isotopic fractionation was observed in all experiments implies that isotopic analysis can provide a direct qualitative indication of whether or not reductive dechlorination of TCE by Fe0 is occurring. This evidence may be useful in answering questions which arise at field sites, such as determining whether TCE observed down-gradient of an iron wall remediation scheme is the result of incomplete degradation within the wall, or of the dissolved TCE plume by passing the wall. 相似文献