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41.
Per capita boron loads reaching 48 sewage treatment works (STWs) in The Netherlands, Germany, Italy, and the UK have been determined from monitoring data. These have been compared with the per capita input predicted from boron in detergents, as determined from detergent product sales data. The resulting distribution of the ratios of measured boron to boron predicted from consumer usage has a 90th percentile of less than 1.5. Boron has previously been shown to be a good marker for substances contained in detergent products, as it cannot be biodegraded and is not substantially adsorbed in the sewer, and there is little or no removal during sewage treatment processes. The monitoring information on the distribution of boron loads found at the different STWs should thus be indicative of the distribution of other substances released to the environment by detergent products, as specified by the relevant industrial category (IC 5-personal/domestic) in the Technical Guidance Documents. Variation in detergent product consumption figures from 18 European countries is also low, with the country with the highest per capita detergent consumption having only 1.3 times the European average detergent use. Thus the present practice of determining a "reasonable worst case" by multiplying the average per capita consumption by a factor of four to account for geographic differences in distribution, is considered to be inappropriate. This should be replaced by a factor of less than two, which combines within country and between country variations to provide a reasonable worst case approximation of the load reaching the sewage treatment facility.  相似文献   
42.
As a result of the UK Government's waste policy, which increasingly encourages sustainable development, and the realisation that water in the UK cannot be treated as an unlimited resource, there is growing interest in reducing the demand for water by industry. A series of industrial waste minimisation clubs have been set up within the country. This paper identifies the effectiveness of these clubs in reducing the demand for water. An overview of some of the clubs show how there is a major discrepancy between potential and implemented water savings, whilst a more detailed analysis of three specific examples show how water demand and cost to the company can be reduced, with the project paying for itself within around 1 year. It appears that companies are able to reduce water consumption by approximately 30%. If this level of saving was taken up by the entire industrial sector in England and Wales, water consumption could be reduced by approximately 1500 Ml/day. This reduction would be more significant in regions of lower rainfall, for example East Anglia and Southeast England.  相似文献   
43.
Theoretical perspectives on resource pulses   总被引:1,自引:0,他引:1  
Holt RD 《Ecology》2008,89(3):671-681
Over the last several decades, there has been a growing appreciation of the importance of nonequilibrial phenomena and transient dynamics in explaining the structure of ecological communities. This paper provides an overview of theoretical themes related to resource pulses. Theoretical models suggest short-term responses to a single pulse can qualitatively differ from longer-term responses. Recurrent resource pulses can alter community structure, permitting coexistence that otherwise would not occur, or hamper coexistence mechanisms effective in stable environments. For a given resource input, system responses can be more dramatic with short pulses. Resource pulses can cause transitions between alternative states. Dispersal permits species to exploit locally sporadic resource pulses and persist in environments that on average are unsuitable. All these issues are ripe for further theoretical explorations.  相似文献   
44.
Sherriff RL  Berg EE  Miller AE 《Ecology》2011,92(7):1459-1470
We used tree ring data (AD 1601-2007) to examine the occurrence of and climatic influences on spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska and found evidence of regional-scale outbreaks dating from the mid-1700s, related to climate variability at multiple temporal scales. Over interannual time scales (approximately 1-3 years), El Ni?o years, combined with severe late-summer drought, appeared to contribute significantly to spruce beetle outbreaks in the study area. Over multidecadal time scales (up to approximately 40 years), cool-phase Pacific Decadal Oscillation (PDO) conditions tended to precede beetle outbreaks, regardless of the phase of El Ni?o-Southern Oscillation (ENSO). All sites showed low-severity disturbances attributed to spruce beetle damage, most notably during the 1810s. During other major periods of disturbance (i.e., 1870s, 1910s, 1970s), the effects of spruce beetle outbreaks were of moderate or higher severity. The highly synchronized timing of spruce beetle outbreaks at interannual to multidecadal scales, and particularly the association between cool-phase PDO conditions and beetle disturbance, suggests that climate (i.e., temperature, precipitation) is a primary driver of outbreaks in the study area. Our disturbance chronologies (mid-1700s to present) suggest that recent irruptions (1990s to present) in south-central and southwest Alaska are within the historical geographic range, but that outbreaks since the 1990s show greater spatiotemporal synchrony (i.e., more sites record high-severity infestations) than at any other time in the past approximatly 250 years.  相似文献   
45.
Marine spatial planning is increasingly used to manage the demands on marine areas, both spatially and temporally, where several different users may compete for resources or space, to ensure that development is as sustainable as possible. Diminishing sea-ice coverage in the Arctic will allow for potential increases in economic exploitation, and failure to plan for cross-sectoral management could have negative economic and environmental results. During the ACCESS programme, a marine spatial planning tool was developed for the Arctic, enabling the integrated study of human activities related to hydrocarbon exploitation, shipping and fisheries, and the possible environmental impacts, within the context of the next 30 years of climate change. In addition to areas under national jurisdiction, the Arctic Ocean contains a large area of high seas. Resources and ecosystems extend across political boundaries. We use three examples to highlight the need for transboundary planning and governance to be developed at a regional level.  相似文献   
46.
47.
We compared the frequency with which 85 Australian organizations espoused nine values (authority, leadership, teamwork, commitment, rewards, normative, participation, performance and affiliation) in 1986–1988 and 1989–1990 through a content analysis of annual reports, internal magazines, and mission statements. We studied value changes both by comparing the frequency of references to single values in the two periods and the frequency with which four, distinctly different values structures (Elite, Leadership, Meritocratic, and Collegial) occurred among organizations in each period. Univariate comparisons over the whole sample revealed only one significant difference—an increase in Commitment references over time. Comparisons based on groups of organizations with different value structures indicated both a preponderance of organizations with Elite values at time one, and that initially Elite organizations showed most evidence of value change. The findings are discussed in terms of the way univariate comparisons of mean shifts in values can mask the presence of significant differences in patterns of value change between organizations, and the utility of content analysis for measuring organizational values unobtrusively. Possible explanations for some of the changes observed are considered.  相似文献   
48.
Vertebrate eggs contain maternal steroid hormones in their yolks; and in avian species the concentration of these steroids vary within and among clutches. The organizational actions of these variable doses of maternal steroids in the avian egg, analogous to those regulating the development of sexually dimorphic traits, are little explored. In this study, we examined the organizational effects of yolk testosterone in the house sparrow, Passer domesticus, a sexually dichromatic passerine bird in which males are characterized by the presence of a throat patch or badge of black feathers that varies in size among males. We injected a physiological dose of testosterone or vehicle into eggs in the field, removed nestlings, and hand-raised them in the laboratory. At 5 months of age, we investigated treatment effects on plumage and behavior. Males that hatched from testosterone-injected eggs developed a larger badge than males that hatched from vehicle-injected (control) eggs. However, testosterone did not induce the expression of a badge in females. In staged dyadic encounters, both males and females hatched from testosterone-injected eggs were more successful at obtaining and defending a food source than individuals of the same sex hatched from control eggs. The results suggest that variable concentrations of maternal testosterone in the eggs of the house sparrow organize the expression of a plumage trait in males and behavior in both sexes.Communicated by J. Graves  相似文献   
49.
RNA:DNA ratios of larval and juvenile red drum (Sciaenops ocellatus) collected from nursery habitats in the Aransas Estuary, Texas, in 1994 were quantified using a highly sensitive ethidium-bromide fluorometric technique. RNA:DNA ratios of wild red drum were evaluated by comparing individual values to a linear regression model derived for starved laboratory-reared red drum. Wild red drum were in relatively good condition with <5% of the RNA:DNA ratios within or below the 95% prediction interval of 4 to 5 d starved red drum. A multiple-regression model explained 54% of the variability in the RNA:DNA ratio of wild red drum, and identified length and water temperature (midday) as significant factors. RNA:DNA ratios increased with fish length [≃1.1 mm−1, over the size range investigated (5␣to 20 mm)]. The effect of temperature on the RNA: DNA ratio was assessed on different sampling trips, and ratios increased with increasing temperature. Abundance of larval and juvenile red drum in the Aransas Estuary varied as a function of both habitat (shoal grass Halodule wrightii, turtle grass Thalassia testudinum) and site (Aransas Bay, Redfish Bay); however, no differences in RNA:DNA ratios were detected between habitats or between sites. It is postulated that the nutritional condition of newly settled red drum from the Aransas Estuary in 1994 was relatively high, and that starvation was of minor importance. Received: 19 August 1996 / Accepted: 23 August 1996  相似文献   
50.
Holt E  Weber R  Stevenson G  Gaus C 《Chemosphere》2012,88(3):364-370
Chlorinated pesticides can contain impurities of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and their precursors, as a result of various manufacturing processes and conditions. As precursor formation of PCDD/Fs can also be mediated by ultraviolet light (UV), this study investigated whether PCDD/Fs are formed when currently used pesticides are exposed to natural sunlight. Formulations containing pentachloronitrobenzene (PCNB; n = 2) and 2,4-dichlorophenoxyacetic acid (2,4-D; n = 1) were exposed to sunlight in quartz tubes, and the concentration of 93 PCDD/F congeners were monitored over time. Considerable formation of PCDD/Fs was observed in both PCNB formulations (by up to 5600%, to a maximum concentration of 57 000 μg ∑PCDD/F kg−1) as well as the 2,4-D formulation (by 3000%, to 140 μg ∑PCDD/F kg−1). TEQ also increased by up to 980%, to a maximum concentration of 28 μg kg−1 in PCNB, but did not change in the 2,4-D formulation. Assuming similar yields as observed in the present study as a worst case scenario the use of PCNB in Australia may result in the formation of 155 g TEQ annum−1, contributed primarily by OCDD formation. This warrants detailed evaluations on the contemporary release of PCDD/Fs to the environment after the use of pesticides. Changes in congener profiles (including the ratio of PCDDs to PCDFs (DF ratio)) suggest that pesticide sources of PCDD/Fs after sunlight exposure may not be recognized based on matching source fingerprints established from manufacturing impurities. These changes also provide preliminary insights into the possible formation routes and types of precursors involved.  相似文献   
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