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There is a growing body of evidence to suggest that certain polycyclic aromatic hydrocarbons (PAHs) pose a greater hazard to aquatic organisms than previously demonstrated, due to their potential to cause photo-induced toxicity when exposed to ultraviolet (UV) radiation. The consequences of photo-induced toxicity are reported here for embryo-larval stages of the pacific oyster Crassostrea gigas, following exposure to pyrene and benzo[a]pyrene. During laboratory investigations, significant increases in toxicity were observed in the presence of environmentally attainable levels of UV-radiation, compared with embryos exposed to PAH alone, at levels previously deemed to have little acute biological effect. The phototoxicity of pyrene and benzo[a]pyrene completely inhibited the development to the D-shell larval stage when embryos were simultaneously exposed to 5 microg l(-1) PAH and ultraviolet light (UVB = 6.3 +/- 0.1 microW/cm2 and UVA = 456.2 +/- 55 microW/cm2). A linear relationship was also demonstrated for benzo[a]pyrene phototoxicity with decreasing UV light intensity. 相似文献
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TS50全站仪配合徕卡多测回测角软件能够自动瞄准、自动观测,具有高智能、高精度的特点,从而在地铁基坑监测领域得到广泛的应用。文章结合济南市轨道交通R1线前大彦站基坑监测项目实践,对测量方法、数据处理、监测效果等方面进行论述。实际应用表明:基于TS50全站仪的多测回测角软件能提供及时可靠的监测数据,科学指导基坑施工,保证了基坑安全,取得良好的效果。 相似文献
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Krahn MM Hanson MB Baird RW Boyer RH Burrows DG Emmons CK Ford JK Jones LL Noren DP Ross PS Schorr GS Collier TK 《Marine pollution bulletin》2007,54(12):1903-1911
“Southern Resident” killer whales include three “pods” (J, K and L) that reside primarily in Puget Sound/Georgia Basin during the spring, summer and fall. This population was listed as “endangered” in the US and Canada following a 20% decline between 1996 and 2001. The current study, using blubber/epidermis biopsy samples, contributes contemporary information about potential factors (i.e., levels of pollutants or changes in diet) that could adversely affect Southern Residents. Carbon and nitrogen stable isotopes indicated J- and L-pod consumed prey from similar trophic levels in 2004/2006 and also showed no evidence for a large shift in the trophic level of prey consumed by L-pod between 1996 and 2004/2006. ∑PCBs decreased for Southern Residents biopsied in 2004/2006 compared to 1993–1995. Surprisingly, however, a three-year-old male whale (J39) had the highest concentrations of ∑PBDEs, ∑HCHs and HCB. POP ratio differences between J- and L-pod suggested that they occupy different ranges in winter. 相似文献
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精密定轨用地球大气模型误差的补偿方法 总被引:1,自引:0,他引:1
本文提出了一种用于精密轨道确定的地球大气模型误差的补偿方法,这种方法采用改进 大气周日峰角的技术,有效地补偿了大气密度模型的误差,并具有较好的物理意义.与传统 的每圈改进一次加速度的方法比较,轨道确定达到了相当的径向精度,且避免了轨道改进参 数间的相关性,同时解算参数的数量也少了一半. 相似文献
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Sediment condition at an Atlantic salmon (Salmo salar) culture site in S.E. Tasmania, Australia was evaluated to determine the rate and extent of recovery after removal of farmed fish. By local standards the cage sediment at the start of this survey was markedly degraded but comparison with results from impact studies in Scotland, Canada and Norway suggests that the sediments were considerably less impacted than in northern temperate areas. The impact at the cages diminished rapidly with both time and distance; after only 2 months conditions were markedly improved. The macrobenthos indicated a slower recovery than chemical measures, after 36 months the benthic faunal community structure under the cages still differed from reference conditions even though other sediment measures had recovered. This study highlighted two other key issues in relation to monitoring and management of sediment recovery. First, techniques used to determine impact may not be appropriate for evaluation of recovery. Second, establishment of local baseline standards is extremely important to ensure appropriate evaluation of both impact and recovery. 相似文献