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11.
This paper discusses processes and factors for estimating time period windows of in situ burning of spilled oil at sea. Time-periods of in situ burning of Alaska North Slope (ANS) crude oil are estimated using available data. Three crucial steps are identified. The First Step is to determine the time it takes for the evaporative loss to reach the known or established limitation for evaporation and compare this time-period with estimated time of ignition at the ambient wind and sea temperatures. The Second Step is to determine the water up-take of the spilled oil and compare it with the known or established limitation for water-in-oil content. The Third Step is to determine the necessary heat load from the igniter to bring the surface temperature of the spilled oil to its flash point temperature so that it will burn at the estimated time period for ignition of the slick. 相似文献
12.
This article summarizes results from raptor monitoring and contamination studies in Norway of the golden eagle, gyrfalcon, white-tailed sea eagle, osprey, peregrine, and merlin. Golden eagle and gyrfalcon populations have been monitored since 1990 as part of the "Monitoring Programme for Terrestrial Ecosystems" (TOV). No long-term trend in the population size or productivity of golden eagle has been shown in any of the 5 study areas. The reproductive output of gyrfalcon is monitored in 3 areas. It is positively correlated with the populations of its main prey species, the rock ptarmigan and the willow ptarmigan. The white-tailed sea eagle population has been monitored since 1974 by the Norwegian Ornithological Society, and the population is increasing. The levels of pesticides and polychlorinated biphenyls are low in the eggs of both the golden eagle and the gyrfalcon, but elevated levels and effects on reproduction have been indicated for a coastal subpopulation of golden eagle. The pollutant levels in white-tailed sea eagle are lower than in the Baltic population of sea eagles, and shell thinning was never severe overall, but individual eggs have contained pollutant concentrations above critical levels. The levels of pollutants in the bird-eating falcons, peregrine, and merlin were higher than in other species. New emerging pollutants, like brominated diphenylethers and perfluorinated organic compounds, could be detected in all species. By incorporating available published and unpublished data, we were able to produce time trends for pollutants and shell thickness over 4 decades. 相似文献
13.
Thorjφrn Larsson 《Ambio-人类环境杂志》2003,32(3):170-175
到目前为止,有关欧洲地表酸化水体大范围化学恢复的文献层出不穷,而有关生物恢复的报道并不多见.建立在现今欧洲排放减少计划之上的模型研究表明,化学恢复仍将继续.而影响恢复进程的诸多不确定性因素主要包括:未来生态系统内氮的可能行为和气候变化的影响.下列4个与气候变化相关的因子可能对未来恢复进程产生影响:①海水盐分入侵事件爆发频率和强度增加;②干旱发生频率和强度上升;③有机碳交换周期加快;④硝化作用增强.目前降低水体酸化程度的国际性协作是成功的,但是未来还有大量问题需要解决,也会遇到许多困难.对未来硫、氮排放减少后以及气候变化背景下酸化地表水体的水化学和水生生物变化需要继续监测. 相似文献
14.
15.
Salmonid Culture and Interspecific Hybridization 总被引:1,自引:0,他引:1
16.
Louise C. Ross Gunnar Austrheim Leif-Jarle Asheim Gunnar Bjarnason Jon Feilberg Anna Maria Fosaa Alison J. Hester Øystein Holand Ingibjörg S. Jónsdóttir Lis E. Mortensen Atle Mysterud Erla Olsen Anders Skonhoft James D. M. Speed Geir Steinheim Des B. A. Thompson Anna Gudrún Thórhallsdóttir 《Ambio》2016,45(5):551-566
17.
Ciannelli L Knutsen H Olsen EM Espeland SH Asplin L Jelmert A Knutsen JA Stenseth NC 《Ecology》2010,91(10):2918-2930
Until the last decade it was assumed that most marine species have pronounced gene flow over vast areas, largely because of their potential for dispersal during early life stages. However, recent genetic, modeling, and field studies have shown that marine populations may be structured at scales that are inconsistent with extensive dispersal of eggs and larvae. Such findings have stimulated the birth of new studies explaining the mechanisms that promote population structure and isolation in the oceans, in the face of high potential for dispersal. Here we study the vertical and horizontal distribution of cod (Gadus morhua) eggs in relation to small-scale circulation and water column hydrography in a coastal location of southern Norway. Previous studies conducted in this region have shown that cod populations inhabiting fjord locations, which are on average 30 km apart, are genetically differentiated, a remarkable outcome considering that Atlantic cod have pelagic egg stages and long pelagic larval duration. We document that cod eggs are found in greater abundance in shallow water layers, which on average are flowing up the fjord (away from the open ocean), and in the inner portion of the fjord, which is subject to lower current speeds compared to the outer or mouth of the fjord. Eggs were found to be neutrally buoyant at shallow depths, a trait that also favors local retention, given the local circulation. The same patterns held during two environmentally contrasting years. These results strongly suggest that population structure of Atlantic cod is favored and maintained by a balance between water circulation and egg characteristics. 相似文献
18.
Summary The linked gas chromatographical/electroan-tennogram (GC/EAG) technique revealed that the parasitic reindeer nose bot fly is able to specifically sense components produced by the interdigital pheromone gland of reindeer. The head-space extraction technique, with Porapak Q as the collecting polymer, was used to trap pheromone gland and urine components used to assess fly responses. One component from reindeer urine also was a potent stimulus for the sensory neurons of the fly. These components can be important chemical signals to the flies for long distance orientation towards host animals. This is the first report on EAG in Oestridae. 相似文献
19.
Jan Atle Knutsen 《Marine Biology》1992,113(4):543-548
The effect of chemical stimuli on the feeding behaviour of turbot (Scophthalmus maximus L.) and sole (Solea solea L.) larvae was investigated under controlled laboratory conditions. Laboratory-reared flatfish larvae exposed to chemical stimuli showed significant differences in the frequency of various behaviour patterns related to feeding (such as swimming, snapping and darting) compared to larvae exposed to blanks of filtrated seawater. The chemical substances Il-asparagine, glycine, inosine 5-monophosphate and betaine evoked the strongest behavioural responses in turbot larvae. In sole larvae the most potent substances were Il-phenylalanine, Il-lysine, Il-asparagine, inosine 5-monophosphate and betaine. These results show that feeding of turbot and sole larvae is influenced by chemosensory processes at an early larval stage, and indicate that chemoreception may be an integrated part of turbot and sole larvae feeding strategy. 相似文献
20.
Total mercury in wild fish in Guizhou reservoirs, China 总被引:2,自引:0,他引:2
Haiyu Yan Atle Rustadbakken Heng Yao Thorjorn Larssen Xinbin Feng Ting Liu Lihai Shang Thrond O. Haugen 《环境科学学报(英文版)》2010,22(8):1129-1136
The health hazard of mercury (Hg) compounds is internationally recognized, and the main pathways for methylmercury (MeHg) intake in humans are through consumption of food, especially fish. Given the large releases of Hg to the environment in China, combined with the fast development of hydropower, this issue deserves attention. Provided similar mobilization pathways of Hg in China as seen in reservoirs in North America and Europe one should expect increased Hg contamination in relation to future hydropower reservoir construction in this country. This study presents total Hg (THg) concentrations in wild fish from six Guizhou reservoirs, China. The THg concentrations in fish were generally low despite high background levels in the bedrock and depositions from local point sources. The over all mean ± SD concentration of THg was (0.066 ± 0.078) μg/g (n = 235). After adjusting for among-reservoir variation in THg, there were significant differences in THg among functional groups of the fish, assumed to re?ect trophic levels. Predicted THg- concentration ratios, retrieved from a mixed linear model, between the functional groups were 9:4:4:1 for carnivorous, omnivorous, planktivorous and herbivorous fish. This result indicated that MeHg accumulation may prevail even under circumstances with short food chains as in this Chinese water system. No fish exceeded recommended maximum THg limit for human consumption set by World Health Organization and the Standardization Administration of China (0.5 μg/g fish wet weight (ww)). Only six fish (2.5%) exceeded the maximum THg limit set by US Environmental Protection Agency (0.3 μg/g fish ww). 相似文献