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971.
The effect of vertical turbulent mixing on the dynamics of persistent organic pollutants has long been overlooked and its role is still hardly understood. Here we present the first comprehensive analysis of the role of turbulent diffusion on the distribution of those contaminants and its interplay with sinking fluxes. To this end, a 1D dynamic coupled hydrodynamic-contaminant model has been developed and applied to a Mediterranean continental shelf environment. The hydrodynamic sub-model is adapted from COHERENS, the contaminant sub-model is an improvement from the BIODEP model and considers the contaminant in 3 phases: dissolved-colloidal-particulate. The simulation highlights the role of turbulence in determining the POP distribution and variability in the water column. In short, turbulent flux of contaminants strengthens the upward diffusion of sediment entrained contaminants and determines the extent to which inputs from the atmosphere mix into the water column. It acts in parallel with degradation and sinking fluxes, the combined effect yielding a surface enriched - depth depleted - benthic layer enriched region distribution, which presents similarities to reported experimental measures. 相似文献
972.
Ship board testing of a deoxygenation ballast water treatment 总被引:2,自引:1,他引:1
McCollin T Quilez-Badia G Josefsen KD Gill ME Mesbahi E Frid CL 《Marine pollution bulletin》2007,54(8):1170-1178
A ship board trial of a deoxygenation method for treating ballast water was carried out during a voyage from Southampton (United Kingdom) to Manzanillo (Panama). A nutrient solution added to two ballast tanks encouraged bacterial growth, resulting in a gradual change to an anoxic environment. Samples were taken from two treated tanks and two untreated tanks to assess changes in the abundance and viability of zooplankton, phytoplankton and bacteria. The work was carried out before the International Maritime Organization (IMO) standard was agreed so only a broad indication of whether the results achieved the standard was given. For the zooplankton, the standard would have been achieved within 5 or 7 days but the phytoplankton results were inconclusive. The biological efficacy was the result of the combination of several factors, including the treatment, pump damage and an increase in the water temperature during the voyage. 相似文献
973.
Factors affecting marine debris deposition at French Frigate Shoals, Northwestern Hawaiian Islands Marine National Monument, 1990-2006 总被引:1,自引:0,他引:1
Data on the amount and type of small debris items deposited on the beaches of the Hawaiian Islands National Wildlife Refuge Tern Island station, French Frigate Shoals were collected over 16 years. We calculated deposition rates and investigated the relationship among deposition and year, season, El Ni?o and La Ni?a events from 1990 to 2006. In total 52,442 debris items were collected with plastic comprising 71% of all items collected. Annual debris deposition varied significantly (range 1116-5195 items) but was not influenced by season. Debris deposition was significantly greater during El Ni?o events as compared to La Ni?a events. Although often deduced to influence floating marine pollution, this study provides the first quantitative evidence of the influence of El Ni?o/La Ni?a cycles on marine debris deposition. 相似文献
974.
Ballesteros E Torras X Pinedo S García M Mangialajo L de Torres M 《Marine pollution bulletin》2007,55(1-6):172-180
Macroalgae is a biological key element for the assessment of the ecological status in coastal waters in the frame of the European Water Framework Directive (WFD, 2000/60/EC). Here we propose a methodology for monitoring water quality based on the cartography of littoral and upper-sublittoral rocky-shore communities (CARLIT, in short). With the use of spatial databases, GIS, and available information about the value of rocky-shore communities as indicators of water quality, it is possible to obtain an environmental quality index representative of the ecological status of rocky coasts. This index, which completely fulfils the requirements of the WFD, is expressed as a ratio between the observed values in the sector of shore that is being assessed and the expected value in a reference condition zone with the same substrate and coastal morphology (Ecological Quality Ratio, EQR). The application of this index to the coast of Catalonia (North-Western Mediterranean) is presented. 相似文献
975.
Among the various quality elements which the Water Framework Directive requires should be monitored are macroalgae. One aspect of these is the presence, in transitional waters particularly, of large blooms of opportunistic macroalgae, such as Ulva and Enteromorpha. Within the United Kingdom (UK) and Republic of Ireland (RoI) there are currently no set ecological quality objectives or standards for macroalgae. Nor are there standard methods for monitoring macroalgal blooms, although various combinations of aerial photography, remote sensing and measurements on the ground are used. This paper attempts to set a logical framework for the prioritisation of sites for monitoring, the development of a tiered monitoring procedure and the derivation of thresholds for classification. Draft threshold limits for percentage cover and biomass of macroalgae have been derived from the literature. The importance of secondary effects and physico-chemical parameters is discussed. 相似文献
976.
对浙江省安吉县梅溪发电厂粉煤灰贮灰场附近的土壤短剖面进行环境磁学、元素含量及粒度研究.借助模糊聚类分析,分辨出粉煤灰原位堆积、富集、迁移深度及未受污染土壤特征.剖面上部0~14cm为粉煤灰的原位反映,多畴磁铁矿主导了该段样品磁性.其中11~14cm处磁性矿物和金属元素有所富集.14~21cm为粉煤灰在土壤中的迁移深度.迁移段土壤中亚铁磁性矿物及Pb、Zn等金属含量介于底部未污染土壤与上部粉煤灰原位堆积层之间.单畴斜交反铁磁性矿物及来源于上部粉煤灰的多畴磁铁矿共同主导了该段土壤的磁性特征.21cm以下土壤基本未受粉煤灰污染,单畴斜交反铁磁性矿物是其主要磁性矿物.指标聚类分析表明,亚铁磁性矿物主要赋存在粗粉砂中,单畴磁晶粒主要存在于细粉砂中.χ、ARM、SIRM与Cu、Mn、Pb、Zn呈显著相关.结合多元统计分析,磁参数可用于追踪、识别粉煤灰在土壤剖面中的垂向迁移. 相似文献
977.
V.R. BELYAEV E. A. EREMENKO A. V. PANIN Y. R. BELYAEV 《国际泥沙研究》2005,20(3):224-232
Two gullies located in the Protva River basin (central part of European Russia, 100 Ion southwest of Moscow) were studied to investigate the history of their development during Late Holocene. This case study included detailed topographic and geomorphologic surveys, geological cross-sections, and radiocarbon dating of organic matter in gully sediments. For both gullies, incision of the long profile occurred for most of the Holocene, as indicated by the limited presence of infill sediment. However, interruptions of incisions occurred in both gullies during the last -3.5 ka (the Chugunkin gully) or -2.0 ka (the Uzkiy gully), as evident from stratigraphic interpretation of the sediment record. Periods of surface stabilization are represented by buried soil horizons, whereas relatively thick sediment layers suggest periods of predominant aggradation. Similarities and differences in discovered sequences of erosion and accumulation stages for the two gullies point out the importance of distinguishing between local and regional controls. Evidence of the role of internal system behavior and self-development in the gully long-term evolution is clear from asynchronous response of different parts of gullies. In recent times (-500 years), active agricultural development of the study territory resulted in accelerated incisions, followed by deposition of catchment-derived material. The latter was limited to the upper parts of the gullies, while incisions have continued in the middle and lower parts. The impact of human activities (-500 years) has been very limited. This suggests that within the forest zone of the Russian Plain many gullies which were earlier attributed to anthropogenic factors are, in realitv, due to natural phenomena. 相似文献
978.
Desmond E.WALLING 《国际泥沙研究》2005,20(1)
It was a great honour and privilege to be elected President of WASER during the first Council meeting, held in Beijing last Saturday. I hope that I will be able to fulfil the expectations of those that elected me and I look forward to serving the Association and promoting its development. As a hydrologist/geomorphologist who started working in the field of erosion and sedimentation some 35 years ago, I have long appreciated the need for, and importance of, interaction with those with simi… 相似文献
979.
Ground water flow and travel time are dependent on stratigraphic architecture, which is governed by competing processes that control the spatial and temporal distribution of accommodation and sediment supply. Accommodation is the amount of space in which sediment may accumulate as defined by the difference between the energy gradient and the topographic surface. The temporal and spatial distribution of accommodation is affected by processes that change the distribution of energy (e.g., sea level or subsidence). Fluvial stratigraphic units, generated by FLUVSIM (a stratigraphic simulator based on accommodation and sediment supply), with varying magnitudes and causes of accommodation, were incorporated into a hydraulic regime using MODFLOW (a ground water flow simulator), and particles were tracked using MODPATH (a particle-tracking algorithm). These experiments illustrate that the dominant type of accommodation process influences the degree of continuity of stratigraphic units and thus affects ground water flow and transport. When the hydraulic gradient is parallel to the axis of the fluvial system in the depositional environment, shorter travel times occur in low-total accommodation environments and longer travel times in high-total accommodation environments. Given the same total accommodation, travel times are longer when sea-level change is the dominant process than those in systems dominated by subsidence. 相似文献
980.
Sánchez F Velasco F Cartes JE Olaso I Preciado I Fanelli E Serrano A Gutierrez-Zabala JL 《Marine pollution bulletin》2006,53(5-7):332-349
Selected key components of the continental shelf benthic and demersal communities were monitored for the two years following the Prestige oil spill (POS) in order to identify the possible ecological effects of the oil. This work includes the first results regarding changes in abundance, distribution and food habits of hake (Merluccius merluccius), four-spot megrim (Lepidorhombus boscii), Norway lobster (Nephrops norvegicus) and Pandalid shrimp (Plesionika heterocarpus) populations of Galician and Cantabrian Sea shelves following the POS. Significant reductions in the abundance of Norway lobster, Plesionika heterocarpus and four-spot megrim were detected in the POS maximum impact area, located over the Galician shelf. Noteworthy recoveries were observed in the 2004 abundance indices of four-spot megrim and Plesionika. On the other hand, no significant effects were detected in the abundance or distribution of hake juveniles even though the tar aggregates were bound by the same oceanographic drift events as the hake recruits were during the winter of 2003 (Navidad current) in different water column layers of the Cantabrian Sea. Feeding patterns of the four species analysed did not present apparent modifications that can be related to the POS. 相似文献