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11.
Produced water discharge accounts for the greater portion of wastes arising from offshore oil and gas production operations. Development and expansion of Canada’s offshore oil and gas reserves has led to concerns over the potential long-term impacts of produced water discharges to the ocean. To examine this emerging environmental issue at a regional scale, an integrated risk assessment approach was developed in this study based on the princeton ocean model (POM), a random walk (RW) and Monte Carlo simulation. The use of water quality standards arrayed in a Monte Carlo design in the developed approach has served to reflect uncertainties and quantify environmental risks associated with produced water discharge. The model was validated against field data from a platform operating off Canada’s east coast, demonstrating its usefulness in supporting effective management of future produced water discharge. 相似文献
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The zebra mussel Dreissena polymorpha, a ponto-caspian byssate bivalve, forms permanent dense populations along the shoreline in the northern part of the inner Neva Estuary. Its total biomass along a 17 km transect reached 4980 tons (mean 1060 g m(-2)) in 2000 and 6510 tons (mean 1385 g m(-2)) in 2001. Being persistent and abundant, the zebra mussel populations played an important role in benthic-pelagic coupling in inner Neva River Estuary. The D. polymorpha population released up to 514 kg day(-1) of dissolved inorganic phosphorus and was, therefore, a major source of bioavailable nutrients in the area. Mussel beds were also efficient biofilters and precipitate 15,020 kg day(-1) of particulate organic matter during the warm season. About 50% of precipitated matter had a relatively long retention time, being utilized within zebra mussel populations, while the rest was deposited as faeces and pseudofaeces and served as a source for organic pollution to the eastern Gulf of Finland. 相似文献
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A fluorescent labelling method is presented as a new tool for the investigation of organic particle transport and biogenic carbon cycling processes in sandy littoral interstices at Lake Tegel, Berlin, Germany. Passive particle transport through the pore system was studied by in situ exposition of 2.4 μm monodisperse polymeric resin microparticles stained with 7-amino-4-methylcoumarin (AMC). Uptake of fluorescein-5-isothiocyanate (FITC)-labelled Chlorella vulgaris and fine particulate organic matter (FPOM) by the interstitial fauna was investigated in laboratory and field experiments. The major portion (>85%) of the FITC-labelled particles added to sediment cores was recovered from the topmost centimetre of sediment during the study period of 14 days. Uptake of FITC-labelled FPOM was observed in several benthic groups, e.g. chironomids, microcrustaceans, oligochaetes and tardigrads, whereas C. vulgaris was ingested by oligochaetes only. There is evidence to suggest that both are suitable materials for investigating the fragmentation and ingestion of organic material by herbivorous and detritivorous fauna. Field experiments with inert microparticles and FITC-labelled FPOM (<1 mm) prepared from dried alder leaves were carried out in plexiglass tubes as in situ whole core technique. Within the investigation period of two weeks, the transport of FPOM was restricted to the topmost 2–3 cm of sediment in conjunction with a distinct fragmentation to finer size classes with respect to increasing sediment depth. Vertical FPOM transport was hindered by a high interstitial concentration of natural POM and an intensive settlement of the interstices by algae (mainly epispammic algae, 65–96% of algae cell number) and extra-cellular polymeric substances (EPS), which formed a dense three-dimensional structure. 相似文献
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为定量化研究影响中国东部近海逆温层产生和发展过程的主要因素,基于Princeton Ocean Model(POM),通过进行河流和暖流的增减试验,对逆温层的季节变化及其影响因素进行了分析。模拟结果显示,受海表失热影响,逆温层主要出现在9月至翌年3月份,山东半岛北部及东部近海、闽浙沿海为三个主要逆温层发生区域,其中山东半岛北部近海逆温层范围和强度最大。当无河流输入时,整个研究海域无逆温层出现,而河流加倍或减半对逆温层的影响主要体现在长江口邻近海域,出现概率分别增高22%和降低15%。当暖流加倍或减半时,长江口邻近海域逆温层出现概率大幅增高23%和降低69%,山东半岛东部近海次之,分别增高34%和降低25%。当关闭暖流时,长江口外海逆温层消失,山东半岛东部近海逆温层出现概率降低约70%,且变浅76%。以上表明,河流淡水是中国东部近海逆温层形成的必要条件,在保持必要河流淡水输入条件下,暖流的变化对中国东部近海逆温层形成的影响比河流变化大,其中对长江口外海影响最大,山东半岛东部近海次之。暖流流量的增减可引起100 m以浅陆架区的海表面高度异常,影响跨40 m等深线海水交换和温盐锋面的形成,造成逆温层大范围的转移和变化。 相似文献
16.
Nutrients in an oligotrophic boundary current: Evidence of a new role for the Leeuwin Current 总被引：1，自引：0，他引：1
P.A. Thompson K. Wild-Allen M. Lourey C. Rousseaux A.M. Waite M. Feng L.E. Beckley 《Progress in Oceanography》2011,91(4):345-359
New observations along the continental shelf of Western Australia provide a novel explanation for the established ∼60 years relationship between Leeuwin Current (LC) strength and greater winter nitrate concentrations at 32°S plus the inter-annual variation in the magnitude of the annual, shelf-scale, phytoplankton bloom. The potential source of dissolved nitrogen to support the annual shelf scale phytoplankton bloom was identified as thin layers of an unprecedented areal extent, nitrate concentration and shallow nature that were observed off the northwest of Australia. We propose that the dissolved inorganic nitrogen (DIN) in these layers enters the LC at depth and then enters the euphotic zone via by three mechanisms: instability that results in a warm core eddy, cooling that deepens the surface mixed layer and shallowing of the thin layer. During the onset of the annual phytoplankton bloom along the west coast of Australia from 22°S to 34°S the poleward flowing LC was clearly evident as a surface intensified ocean boundary current transporting warmer, lower-salinity, greater-silicate waters in a shallow mixed layer rapidly southward. Between 24 and 26°S the core of the LC was present as a 50–100 m deep layer over one or more thin layers, 15–50 m thick, with high nitrate and low dissolved oxygen (DO). These layers were of lower salinity, cooler water with markedly reduced DO, high nitrate concentrations and distinct nitrate:silicate (NO3:Si(OH)4) nutrient ratios. As the LC flowed south it cooled and deepened thereby entraining the thin layers of high nitrate water into the euphotic zone. The LC also formed large (greater than 100 km diameter) warm core eddies with a deep surface mixed layer that also entrained nitrate from these thin layers. In some locations as far south as 32°S the LC was still present with the thin layer of high nitrate intact but now within the euphotic zone. Thus, the available evidence suggests the LC arises under conditions that favour rapid and shallow nitrification. This nitrification fuels a shelf-scale bloom on a downwelling favourable coast. Depending upon the rate of nitrification the source of the particular organic matter may be local or delivered from the tropics via horizontal advection in a subsurface layer of the LC. 相似文献
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北部湾的环流和水团对季节性强迫的响应 总被引：1，自引：1，他引：0
In the past 20 a, the gulf-scale circulation in the Beibu Gulf has been commonly accepted to be driven by a wind stress or density gradient. However, using three sensitive experiments based on a three-dimensional baroclinic model that was verified by observations, the formation mechanisms were revealed： the circula- tion in the northern Beibu Gulf was triggered by the monsoon wind throughout a year; whereas the southern gulf circulation was driven by the monsoon wind and South China Sea （SCS） circulation in winter and sum- mer, respectively. The force of heat flux and tidal harmonics had a strong effect on the circulation strength and range, as well as the local circulation structures, but these factors did not influence the major circulation structure in the Beibu Gulf. On the other hand, the Beibu Gulf Cold Water Mass （BGCWM） would disappear without the force of heat flux because the seasonal thermocline layer was generated by the input of heat so that the vertical mixing between the upper hot water and lower cold water was blocked. In addition, the wind-induced cyclonic gyre in the northern gulf was favorable to the existence of the BGCWM. However, the coverage area of the BGCWM was increased slightly without the force of the tidal harmonics. When the model was driven by the monthly averaged surface forcing, the circulation structure was changed to some extent, and the coverage area of the BGCWM almost extended outwards 100%, implying the circulation and water mass in the Beibu Gulf had strong responses to the temporal resolution of the surface forces. 相似文献
19.
作者阐述了聚甲醛污水的水质特点,提出了聚甲醛污水工程的设计要点,介绍了两个聚甲醛污水工程实例,并对已实施的工程进行了总结。 相似文献
20.