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91.
92.
F.O. Ongondo I.D. Williams J. Dietrich C. Carroll 《Waste management (New York, N.Y.)》2013,33(12):2600-2606
In Europe, socio-economic enterprises such as charities, voluntary organisations and not-for-profit companies are involved in the repair, refurbishment and reuse of various products. This paper characterises and analyses the operations of socio-economic enterprises that are involved in the reuse of Information and Communication Technology (ICT) equipment. Using findings from a survey, the paper specifically analyses the reuse activities of socio-economic enterprises in the UK from which Europe-wide conclusions are drawn. The amount of ICT products handled by the reuse organisations is quantified and potential barriers and opportunities to their operations are analysed. By-products from reuse activities are discussed and recommendations to improve reuse activities are provided. The most common ICT products dealt with by socio-economic enterprises are computers and related equipment. In the UK in 2010, an estimated 143,750 appliances were reused. However, due to limitations in data, it is difficult to compare this number to the amount of new appliances that entered the UK market or the amount of waste electrical and electronic equipment generated in the same period. Difficulties in marketing products and numerous legislative requirements are the most common barriers to reuse operations. Despite various constraints, it is clear that organisations involved in reuse of ICT could contribute significantly to resource efficiency and a circular economy. It is suggested that clustering of their operations into “reuse parks” would enhance both their profile and their products. Reuse parks would also improve consumer confidence in and subsequently sales of the products. Further, it is advocated that industrial networking opportunities for the exchange of by-products resulting from the organisations’ activities should be investigated. The findings make two significant contributions to the current literature. One, they provide a detailed insight into the reuse operations of socio-economic enterprises. Previously unavailable data has been presented and analysed. Secondly, new evidence about the by-products/materials resulting from socio-economic enterprises’ reuse activities has been obtained. These contributions add substantially to our understanding of the important role of reuse organisations. 相似文献
93.
S. A. Power M. R. Ashmore A. C. Terry S. J. M. Caporn M. G. Pilkington D. B. Wilson C. G. Barker J. A. Carroll N. Cresswell E. R. Green G. W. HEIL 《Water, Air, & Soil Pollution: Focus》2004,4(6):259-267
The results from three long-term field manipulation studies of the impacts of increased nitrogen deposition (0–120 kg N ha–1 yr–1) on lowland and upland heathlands in the UK were compared, to test if common responses are observed. Consistent increases in Calluna foliar N content and decreases in litter C:N ratios were found across all sites, while increases in N leaching were not observed at any site over the range 0–80 kg ha–1 yr–1. However, the response of Calluna biomass did vary between sites, possibly reflecting site differences in nutrient status and management histories. Five versions of a simulation model of heathland responses to N were developed, each reflecting different assumptions about the fate and turnover of soil N. Model outputs supported the deduction from mass balance calculations at two of the field sites that N additions have resulted in an increase in immobilisation; the latter was needed to prevent the model overestimating measured N leaching. However, this version of the model significantly underestimated Calluna biomass. Model versions, which included uptake of organic N by Callunaand re-mobilisation of N from the soil organic store provided some improvement in the fit between modelled and field biomass data, but re-mobilisation also led to an overestimation of N leaching. Quantification of these processes and their response to increased N deposition are therefore critical to interpreting experimental data and predicting the long-term impacts of atmospheric deposition on heathlands and moorlands. 相似文献
94.
95.
John M. Carroll Bradley J. Peterson Dennis Bonal Andrew Weinstock Christopher F. Smith Stephen T. Tettelbach 《Marine Biology》2010,157(2):249-259
Eelgrass, Zostera marina, is generally regarded as the preferred habitat of bay scallops, but in some cases scallop populations have persisted or
increased in areas lacking eelgrass. This suggests that some other substrate(s) may serve important ecological functions for
bay scallops. One candidate is Codium fragile, a macroalgal species with which bay scallops are known to associate and in which we commonly find juvenile and adult bay
scallops in eastern Long Island, New York. In this study, we examined whether survival of planted bay scallops differed in
Codium, eelgrass, and Codium + eelgrass substrates at two sites during August and October of 2 years. Survival of tethered scallops and recoveries of
live free-planted individuals varied with scallop size, planting season and year, but no differences were observed between
the three substrates for a given scallop size and planting date. Crab (particularly Dyspanopeus
sayi) and whelk predation were implicated as important causes of tethered scallop mortalities while emigration and removal by
predators likely contributed to scallop losses. Densities of naturally recruited 0+ years scallops recovered by visual and
suction dredge sampling were similar in the eelgrass and Codium substrates. While our results suggest that Codium may offer some degree of predation refuge for bay scallops, further work needs to weigh the potential disadvantages of this
substrate (such as low DO levels, potential attachment and transport of scallops, and differences in current flow, food availability
and sedimentation relative to eelgrass) to determine if Codium may serve as a valuable habitat for bay scallops throughout their lifespan. 相似文献
96.
Jolyon J. Faria John R. G. Dyer Romain O. Clément Iain D. Couzin Natalie Holt Ashley J. W. Ward Dean Waters Jens Krause 《Behavioral ecology and sociobiology》2010,64(8):1211-1218
Collective animal behaviour has attracted much attention recently, but cause-and-effect within interaction sequences has often
been difficult to establish. To tackle this problem, we constructed a robotic fish (‘Robofish’) with which three-spined sticklebacks
(Gasterosteus aculeatus L.) interact. Robofish is a computer-controlled replica stickleback that can be programmed to move around a tank. First,
we demonstrated the functioning of the method: that the sticklebacks interacted with Robofish. We examined two types of interaction:
recruitment and leadership. We found that Robofish could recruit a single fish from a refuge and could initiate a turn in
singletons and in groups of ten, i.e. act as a leader. We also showed that the influence of Robofish diminished after the
first 30 min that fish spent in a new environment. Second, using this method, we investigated the effects of metric and topological
inter-individual distance on the influence that Robofish had on the orientation of fish in a shoal of ten. We found that inter-individual
interactions during this turn were predominantly mediated by topological, rather than metric, distance. Finally, we discussed
the potential of this novel method and the importance of our findings for the study of collective animal behaviour. 相似文献
97.
The frequently observed positive correlation between species diversity and community biomass is thought to depend on both the degree of resource partitioning and on competitive dominance between consumers, two properties that are also central to theories of species coexistence. To make an explicit link between theory on the causes and consequences of biodiversity, we define in a precise way two kinds of differences among species: niche differences, which promote coexistence, and relative fitness differences, which promote competitive exclusion. In a classic model of exploitative competition, promoting coexistence by increasing niche differences typically, although not universally, increases the "relative yield total", a measure of diversity's effect on the biomass of competitors. In addition, however, we show that promoting coexistence by decreasing relative fitness differences also increases the relative yield total. Thus, two fundamentally different mechanisms of species coexistence both strengthen the influence of diversity on biomass yield. The model and our analysis also yield insight on the interpretation of experimental diversity manipulations. Specifically, the frequently reported "complementarity effect" appears to give a largely skewed estimate of resource partitioning. Likewise, the "selection effect" does not seem to isolate biomass changes attributable to species composition rather than species richness, as is commonly presumed. We conclude that past inferences about the cause of observed diversity-function relationships may be unreliable, and that new empirical estimates of niche and relative fitness differences are necessary to uncover the ecological mechanisms responsible for diversity-function relationships. 相似文献
98.
Transport of molybdenum in a biosolid-amended alkaline soil 总被引:3,自引:0,他引:3
The transport of molybdenum (Mo) in a biosolid-amended, alkaline, agricultural soil was examined in the research reported herein. Batch-equilibrium and miscible-displacement experiments were conducted to examine the transport of Mo in soil with and without 10% by weight biosolid amendment. The results of geochemical modeling, conducted using PHREEQC, indicated that no mineral dissolution or precipitation reactions were expected for the system under the prevailing conditions. Sorption equilibrium coefficients (Kd) obtained from moment analysis of the Mo breakthrough curves were similar to those calculated from the results of the batch-equilibrium experiments. Mo sorption was greater for the biosolid-amended soil (Kd of 1.3 versus 0.35). Sorption of Mo was shown to be linear, rate limited, and reversible for both unamended and amended soil. The results suggest that Mo associated with biosolid-amended soils is relatively bioavailable and mobile. 相似文献
99.
Xiaoge Huang Lihao Chen Ziqi Ma Kenneth C. Carroll Xiao Zhao Zailin Huo 《Frontiers of Environmental Science & Engineering》2022,16(12):151