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151.
Landfill is the cheapest method of domestic waste disposal but the amount disposed of in this way has declined in recent years. This decline in landfill is due principally to the unavailability of acceptable tipping sites. Up to 30% of land taken for sand and gravel extraction may not be restored to a productive use in the absence of fill material. Domestic waste is often available to reclaim derelict sand and gravel quarries, but unsubstantiated fears of tip leachate polluting groundwaters has prevented its use for this purpose. 相似文献
152.
John T. Mirenda Doug G. Eakins Karen Gravelle Howard Topoff 《Behavioral ecology and sociobiology》1980,7(2):119-127
Summary Colonies of Neivamyrmex nigrescens conduct extensive nocturnal raids on other ants and termites in the desert-grassland of Arizona-New Mexico. We collected quantitative data on several aspects of raiding to pinpoint differences due to colony size and behavioral phase. In the nomadic phase, colonies began raiding at sunset and continued until dawn. Larger colonies covered more area, discovered more prey sites, and collected more booty than smaller colonies, but there were no systematic changes in raid intensity over the course of the nomadic phase. In the statary phase, raiding occurred less frequently and was less intense when it occurred; however, at the end of this phase, raiding was similar to nomadic phase raids in extent, duration, and booty captured.
N. nigrescens preyed exclusively on termites and ants, and appeared to select certain species of Pheidole in preference to other ants. Pheidole was the most abundant genus, but was preyed upon twice as often as expected based on relative colony density. Pheidole attempted to avoid predation by fleeing or defending their nest, but rarely succeeded. Because they are about the same size as army ants and lack defensive chemicals, Pheidole made comparatively easy prey.
N. nigrescens ignored or was repelled by other ants (Pogonomyrmex, Novomessor, Iridomyrmex, Myrmecocystus) during the early summer, when Pheidole was abundant; however, in late summer when Pheidole was less available, the army ants preyed upon Novomessor cockerelli.
N. harrisi raided in close proximity to N. nigrescens, but preyed exclusively on Solenopsis xyloni. Selection of prey and partitioning of resources are now indicated in several army ant species; these processes have probably been important factors in the evolution of the ants' predatory behavior. 相似文献
153.
Field observations on the emergence rhythm of the Norway lobsterNephrops norvegicus,using different methods 总被引:4,自引:0,他引:4
The emergence ofNephrops norvegicus (L.) from their burrows was studied on several fishing grounds around Scotland at 28 to 62 m depth. Various methods were used: sampling by trawl and baited creels, observations by television and time-lapse cameras. Peak emergence generally occurred around dusk and dawn. In shallow water (30 m) there was also a significant level of activity during the intervening night period. Day/night variations in the size composition of catches suggest that relatively more time is spent out of the burrow with increasing size. There was good agreement between the various methods employed, suggesting that trawl and camera avoidance has little influence on the pattern of emergence observed. The use of bait in some experiments confirmed that emergence is essentially a feeding activity. 相似文献
154.
Intertidal mudflats are important nursery grounds for juveniles of many fish species. However, they are being used increasingly to farm bivalve molluscs, which produce large amounts of organic “fluff”, overlying the mud. Fish such as sole, Solea solea, hide in this fluff from potential predators, but the energy consumed by respiring the fluff may be high due to its biorheological properties. We developed an ichthyoviscometer. It incorporates a freshly killed fish as a viscometer, and we developed it to measure the rheological properties of fluids and suspensions, including fluff, at scales encompassing those in gill ventilation. We have shown that the rheological behaviour of fluff is close to that of a gel with a yield stress strongly dependent on particulate organic matter concentration ([POM]). This has allowed us to model fluff flow through the gill channels in living sole as a function of fish size and [POM], showing that in a 26-g sole, fluff would halve flow at a [POM] value of 3.2 g l−1, and stop it at 3.4. 相似文献
155.
The enhancement of solute diffusivities within coastal surficial sediments as a result of wave action is examined. Fluctuating pressure gradients associated with passing waves cause interstitial water motions leading to enhanced diffusivities through the mechanism of shear dispersion. Wave amplification of diffusivities is likely to be greatest for waves of period 10 s, in shallow water, over a bottom of coarse grain. Diffusivity enhancement of hundreds of times molecular diffusivity is achievable. The mechanism is distinct from, but complements, the mechanism of rotational dispersion which has been previously described. Other mechanisms that enhance solute transport within surficial sediments rely on the interaction between wave-driven or steady flow over bottom obstructions such as biogenic structures or sand ripples. It is suggested that while the resulting advective flows may dominate solute transport within the top few 10 s of centimeters of the sediment column, shear dispersion may be more important deeper within the sediment. In any event, in contrast to these other mechanisms, shear dispersion is operative even when the seabed is flat. Application of the theory to sediments of the South Atlantic Bight would suggest that shear dispersion is capable of explaining a major part of the interstitial transport inferred from measurements. 相似文献
156.
The distribution and enrichment of selected trace metals (Cd, Cr, Cu, Ni, Pb, Sn, Zn) in benthic sediments of the Southport
Broadwater, a semi-enclosed coastal body of water adjacent to the Gold Coast city, south-eastern Queensland, Australia, was
studied with the objective of assessing the extent and degree of sediment contamination. Sediment samples from the 0–10 cm
and 10–20 cm depth intervals of 32 sites within the Southport Broadwater and surrounding residential canals were analysed
for particle size distribution, pH, organic C and ‘near-total’ major (Al, Ca, Fe, Mn) and trace (Cd, Cr, Cu, Ni, Pb, Sn, Zn)
metal contents. Sediment contamination for each trace metal was assessed by (1) comparison with Australian sediment quality
guidelines, (2) calculation of the index of geoaccumulation based on regional background values, and (3) geochemical normalisation
against Al (i.e. the abundance of alumino-silicate clay minerals). Based on this approach, the results indicate that submerged
sediments in the study area are not presently enriched with Cd, Cr or Ni, with the spatial distribution of these metals being
very well explained by the abundance of alumino-silicate clay minerals. However, several sites were strongly enriched with
Cu, Pb, Sn and Zn, arising from sources related to either urban runoff or vessel maintenance activities. The study indicates
that several varying approaches are needed for a satisfactory assessment of contaminant enrichment in estuarine sediments. 相似文献
157.
Felicia J. Higgs Howard W. Mielke Michelle Brisco 《Environmental geochemistry and health》1999,21(1):27-36
Soil studies, conducted in Maryland, Minnesota and Louisiana, have described the urban pattern of lead contamination. They have shown that the highest amounts of lead cluster within the interior of the largest cities. The results of the New Orleans urban patterns of distribution of soil lead provided the basis for further study. The hypothesis was tested that elementary school properties have the same pattern of soil lead contamination as their neighbouring residential communities. Thirty New Orleans Public Elementary Schools were selected for this study. Surface samples (2.5cm or 1 inch depth) were collected from playgrounds and next to entrances of each school. Results showed that soil lead on school properties follows the same relative contamination patterns (pvalue10–5) as soil lead on residential properties of neighbouring communities. Schools however, have significantly lower lead contamination than the neighbouring residential properties. Innercity school properties present a higher risk of soil lead exposure than mid and outercity schools. Soils next to innercity school entrances showed the highest lead, with 18.5% having concentrations over 400gg–1. Systematic landscaping around the school entrances would significantly reduce the hazard from lead dust contaminated soils. 相似文献
158.
Adaptation Options Strategies for Hazards and Vulnerability Mitigation: An International Perspective
C.?Emdad?HaqueEmail author Ian?Burton 《Mitigation and Adaptation Strategies for Global Change》2005,10(3):335-353
The broad objective of this special issue of Mitigation and Adaptation Strategies for Global Change is to address some of the gaps in our knowledge and understanding of the policies, programs, and measures that might be applied
to natural hazards and their impacts in an era of climate change. Given the global impacts of climate change and world-wide
pattern of increasing losses from natural hazards we necessarily adopt an international perspective. The specific goals of
the special issue are to: (a) encompass experiential aspects, emphasizing current practice of mitigation and its associated
measures, and their results; and (b) explore primary or root causes of alarming shifts in human and economic costs of environmental
extremes. Special emphasis is placed on how human activities are playing a key role in enhancing vulnerability to NTEE (nature-triggered
environmental extremes), quite independently from the anthropogenic causes of climate change. The goals are also (c) to examine
costs, risks, and benefits (of all kinds including social, political, ecological) of mitigation, and adjustment and adaptation
measures; and (d) analyze policy implications of alternative measures. These components are expected to make significant contributions
to policy considerations – formulation, implementation and evaluation. There is much uncertainty about the rate of climate
change; however, the fact of increase of the atmospheric temperature in the last century is no longer a subject of scientific
or policy debate. Due to such changes in the geophysical parameters, certain types of nature-triggered environmental extreme
events are likely to continue to increase. How global warming will affect regional climates and pertinent variables is not
well known, limiting our ability to predict consequential effects. This factor poses serious constraints against any straightforward
policy decisions. Research findings of the work of this volume reaffirm that human dimensions, specifically our awareness
and decision-making behavior, are powerful explanatory factors of increasing disaster losses. Disaster mitigation through
addressing human, social, and physical vulnerability is one of the best means for contributing to ‘climate change adaptation
plans’, and sustainable development goals. Recent lessons from various countries have depicted that the formulation of mitigation
strategies cannot be exclusively top-down as it requires social, political, and cultural acceptance and sense of ownership.
An interactive, participatory process, involving local communities, produces best expected outcomes concerning mitigation,
preparedness, and recovery. An emerging consensus is that there is a need to move towards the ‘mission’ of the International
Strategy for Disaster Reduction which aims at building disaster resilient communities by promoting increased awareness of
the importance of disaster reduction as an integral component of sustainable development, with the goal of reducing human,
social, economic and environmental losses due to natural hazards and related technological and environmental disasters. Sharing
of best practices and lessons globally is certain to produce more efficiency and understanding in policy and decision making. 相似文献
159.
Polychlorobiphenyls (PCBs) and pesticides are persistent, semivolatile contaminants whose global circulation is now well established. One of their ultimate sink is the bio- and geo-phases in the deep-sea. We have investigated the distribution of selected PCBs and pesticides with depth and longitude in various deep-sea fish, namely black scabbardfish (Aphanopus carbo), orange roughy (Hoplostethus atlanticus), roundnose grenadier (Coryphaenoides rupestris) and Bathysaurus ferox from Madeira, Sesimbra, the Meriadzec Terrace and Rockall Trough in the North Eastern Atlantic at 1000 m depth, and at 2000 m depth where available. In most species, males presented higher levels of contamination than females. This pattern was probably due to the females eliminating contaminants through egg production. Roundnose grenadier presented higher levels of contamination (mainly p,p'-DDE, CB 153, 138, 180, sigmaCB(24) and p,p'-DDT) in fish caught at 2000 m than at 1000 m depth. Similarly, B. ferox, which is found deeper than the other species studied, showed much higher levels of most CBs and pesticides (lipid normalised) than the other species. Concentrations were up to 10 times higher, and showed differences between water masses. 相似文献
160.
Ian Hammond K. Robert Müller 《Environmental science and pollution research international》1995,2(3):175-178
The disposal of hazardous and toxic wastes is an area where utmost care and responsibility needs to be exercised. A certain
(and mostly acceptable) level of care and responsibility has been legislated and is in place in most developed economies (UK,
USA, Canada, Europe, etc.). This is, however, generally not the case in under-developed or developing economies, South Africa
being no exception.
This paper reflects on various disposal methods and describes a potentially economic alternative to existing methods of the
disposal of toxic and hazardous wastes. These existing methods are: Disposal in Class I landfill sites and destruction via
incineration. 相似文献