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181.
Retreat and advance of shoreline position occurs naturally, and also as a result of defences which are constructed to prevent
erosion and flooding. Retreat more commonly manifests itself down-drift of defences due to a sediment deficit causing the
coast to become ‘set-back’. Advance normally develops due to sediment accumulation up-drift of a barrier inhibiting longshore
drift, resulting in the coast becoming ‘set-forward’. Many examples of set-backs and set-forwards are recorded, but their
location, number and cause is not known on a national scale. Using the Futurecoast aerial photographs, approximately 200 localities
were identified as set-back or set-forward in England and Wales, with half situated in the Eastern and South East regions
of England. Half of the total set-backs or set-forwards were on cliffed coasts, and half on low-lying coasts. Without local
knowledge it is difficult to distinguish between set-backs and set-forwards. Set-backs often indicate higher retreat rates,
thus threatening cliff-top infrastructure which requires defence upgrade and extensions, as well as raising maintenance costs.
Monitoring set-backs is important for shoreline management, because as retreat continues, set-backs evolve and artificial
headlands form and grow. This is reinforced by the shift from hard defence policies towards softer engineering approaches,
managed realignment and limited intervention. 相似文献
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Paul Scott Paul Brown Julia Verne Jody James Alistair Gordon Joyshri Sarangi Jonathan A. C. Sterne 《Environmental geochemistry and health》2009,31(2):297-308
This ecological study aimed, through the analysis of 1,146 wards in the South West of England (1998–2002), firstly, to examine
whether chemical incidents and public casualties are more likely near complex industry (emissions to land, air or water: Integrated
Pollution Control industry, IPC) or industry with emissions to air only (Local Air Pollution Control industry, LAPC). Secondly,
the study examined whether industry, incidents and casualties are found close to deprivation. Social inequalities were examined
across quintiles of wards. Fifty-two wards (4.5%) contained an IPC industry and 712 (62.1%) an LAPC. Incidents occurred in
132 wards (11.5%), with casualties in 59 (5.1%). Chemical incidents occurred more frequently in wards with LAPC (152, IPC
20); the same was true of casualties (211, 12). With each additional LAPC site in a ward, the risk of an incident rose by
22% (95% confidence interval [CI] 8–38%), suggesting a dose–response relationship. No clear social inequalities were found.
In the South West of England, the public are more likely to be affected by an incident occurring at a simple LAPC site rather
than a complex IPC site. This has implications for emergency planning which, at present, focusses most attention on the larger,
more complex IPC sites. 相似文献
184.
Richard A. Brown James G. Mueller Alan G. Seech James K. Henderson John T. Wilson 《补救:环境净化治理成本、技术与工艺杂志》2009,20(1):9-20
While biologically mediated reductive dechlorination continues to be a significant focus of chlorinated solvent remediation, there has been an increased interest in abiotic reductive processes for the remediation of chlorinated solvents. In situ chemical reduction (ISCR) uses zero‐valent iron (ZVI)–based technologies, such as nanoscale iron and bimetallic ZVI, as well as naturally occurring reduced minerals incorporating dual‐valent iron (DVI), such as magnetite, green rust, and iron sulfides that are capable of dechlorinating solvents. A more recent area of development in ISCR has been in combining biological and abiotic processes. There are several ways in which biological and abiotic processes can be combined. First, the interaction between the two may be “causative.” For example, the Air Force Center for Engineering and the Environment's biogeochemical reductive dechlorination (BiRD) technology combines a mulch barrier with hematite and gypsum to create an iron‐sulfide‐based reducing zone. Biodegradation under sulfate‐reducing conditions produces sulfide that combines with the hematite to form iron sulfides. As such, the BiRD technology is “causative”; the biological processes create reducing minerals. The biological generation of other reducing minerals such as magnetite, siderite, and green rust is feasible and is, with magnetite, observed in nature at some petroleum sites. A second type of interaction between abiotic and biotic processes is “synergistic.” For example, biological processes can enhance the activity of reduced metals/minerals. This is the basis of the EHC® ISCR technologies, which combine ZVI with a (slowly) degradable carbon substrate. This combination rapidly creates buffered, strongly reducing conditions, which result in more complete solvent degradation (i.e., direct mineralization). The extent and level of reducing activity commonly observed are much greater when both the carbon substrate and the ZVI are present. When the carbon substrate is expended, the reducing activity due to ZVI alone is much less. The understanding of biogeochemical processes and their impact on abiotic processes is still developing. As that understanding develops, new and improved methods will be created to enhance volatile organic compound destruction. © 2009 Wiley Periodicals, Inc. 相似文献
185.
The extant deep-sea fauna is thought to result from recolonisation of this environment by shallow-water organisms following climate-driven mass extinctions. Planktonic larval tolerance to high pressure is considered an important preadaptation for successful deep-sea invasion. In this study, the pressure and temperature tolerance of a species without any known confamilial deep-sea relative were assessed for the first time. Early- and late-veliger larvae of the shallow-water species Crepidula fornicata were subjected to a temperature/hydrostatic pressure regime from 5 to 25 °C and from 0.1 to 40 MPa. Although early and late veliger survived pressures equivalent to 2,000 m water depth or greater at all temperatures, decreased larval activity indicated significant sublethal temperature and pressure effects. Reduced larval activity of early veliger at low temperatures suggests that the bathymetric range of this species may be thermally constrained. A mechanistic model is proposed to explain the emerging pattern of ontogenetic shifts in pressure tolerance of shallow-water benthic invertebrates. 相似文献
186.
Lester R.Brown 《生态毒理学报》2000,22(2):72-74
本世纪期间,技术进展已经使农作物生产率发生了革命,但农作物产率的提高已经开始放慢,而世界人口却继续增长.土地退化和水资源的压力是对非常需要的土地生产率提高的严重障碍.满足21世纪全球食品需要将要求一致的人口控制政策,推进可持续消费,和大大提高我们对土地、水及其它自然资源的使用效率.本文提供了对这些问题的前瞻性分析和解决这些问题的建议. 相似文献
187.
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Clyde M. Smith William E. Brown 《Journal of the Air & Waste Management Association (1995)》2013,63(7):1015-1019
Collectively, surface coating operations using paints with hydrocarbon solvents may well be the largest industrial source of volatile organic compounds (VOC) and hazardous air pollutants (HAP). Most surface coating operations involve the manual application of paint with spray equipment inside a paint spray booth. The booth exhaust system collects the solvent fumes and then exhausts them through a stack to the atmosphere. Stack emissions are characteristically high in flow rate and low in concentration. Since control equipment is sized based on exhaust flow rate rather than concentration, control of VOC and HAP requires large, expansive abatement equipment. Simple, effective designs employing recycling of air have greatly reduced the exhaust flow rate and the cost of the control equipment. However, these designs are not popular because they are burdened by various flaws, notably worker endangerment. The Mobile Zone recirculation system can be incorporated into new construction or retrofitted to existing spray booths and will reduce the exhaust volumes ranging from 65 to 95 percent without adversely affecting the production rate, production quality or worker safety. 相似文献
190.