排序方式： 共有53条查询结果，搜索用时 15 毫秒
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Ford AT Read PA Jones TL Michino F Pang Y Fernandes TF 《Marine environmental research》2007,64(4):443-455
The amphipod, Echinogammarus marinus, is common in sheltered coastal inlets, such as estuaries and sea lochs, in Scotland and exhibits increased levels of intersex in some contaminated areas. Sea lochs are commonly the location for coastal aquaculture development, and some chemicals used in fish-farming are specifically designed to target the crustacean nervous system. Therefore it was hypothesised that these chemicals may also affect neuro-endocrine pathways, causing morphological and reproductive abnormalities in non-target Crustacea. Based upon this hypothesis, Echinogammarus marinus amphipods from two different Scottish sea lochs containing salmon farms were investigated. Morphology, intersexuality, and the incidence of microsporidian parasites were recorded at sites close and at distance from fish-farms. Results suggest a higher incidence of intersexuality at sites within sea lochs, comparable to that observed in industrially contaminated sites elsewhere in Scotland. The data suggest that fish farming activity may influence the observed distributions of intersexuality within lochs. Intersex specimens were more likely to be infected by microsporidian parasites than non-intersex specimens. Normal females were found more likely to be infected by microsporidian parasites at sites associated with high intersexuality, suggesting the parasite as the probable feminiser. The cause(s) for the observed patterns of intersexuality are unclear, although suggestions relating to discharges from fish farms are discussed. 相似文献
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Differences in physiological response to increased seawater temperature in nearshore and offshore corals in northern Vietnam 总被引：1，自引：0，他引：1
Faxneld S Jörgensen TL Nguyen ND Nyström M Tedengren M 《Marine environmental research》2011,71(3):225-233
Effects of elevated seawater temperature show high spatial heterogeneity and variation within and among coral species. The objective of this study was to investigate how two coral species, Porites lutea and Galaxea fascicularis, from two high latitude reefs differently exposed to chronic disturbance, respond to elevated seawater temperatures. Corals were collected from reefs nearshore (i.e. subjected to high sediment load, higher chlorophyll α concentrations, turbidity etc.) and offshore (i.e. less exposed). The corals were exposed in the lab to gradually increasing temperatures (25.5-33.5?°C) for 72?h after which they were allowed to recover to ambient temperature (25.5?°C) for 24?h. Production and respiration were measured after 24, 48, 72 and 96?h. The results show that P. lutea from nearshore reefs suffered an initial decrease in gross primary production/respiration (GP/R) ratio after 24?h, after only a moderate temperature increase (+2?°C, from 25.5 to 27.5?°C), while there was no difference in GP/R ratio between heat-exposed and controls the other days, indicating that the chronic disturbance in the nearshore reef had no effect on their thermotolerance. Furthermore, P. lutea from the offshore reef showed a decrease in GP/R ratio both after 24?h and 72?h (33.5?°C) of exposure. In comparison, G. fascicularis showed a decrease in GP/R ratio after 48?h, 72?h and 96?h of exposure for the nearshore corals. Also, after 72?h these corals had withdrawn their polyps. There were no differences between heat-treated and controls for the offshore G. fascicularis. This implies that the chronically disturbed G. fascicularis had lower thermotolerance when exposed to a temperature increase. This study, hence, shows that the response of corals to elevated seawater temperature varies with species and environmental background history. 相似文献
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Ley-Quiñónez C Zavala-Norzagaray AA Espinosa-Carreón TL Peckham H Marquez-Herrera C Campos-Villegas L Aguirre AA 《Marine pollution bulletin》2011,62(9):1979-1983
Environmental pollution due to heavy metals is having an increased impact on marine wildlife accentuated by anthropogenic changes in the planet including overfishing, agricultural runoff and marine emerging infectious diseases. Sea turtles are considered sentinels of ecological health in marine ecosystems. The objective of this study was to determine baseline concentrations of zinc, cadmium, copper, nickel, selenium, manganese, mercury and lead in blood of 22 clinically healthy, loggerhead turtles (Caretta caretta), captured for several reasons in Puerto López Mateos, Baja California Sur, Mexico. Zinc was the most prevalent metal in blood (41.89 μg g−1), followed by Selenium (10.92 μg g−1). The mean concentration of toxic metal Cadmium was 6.12 μg g−1 and 1.01 μg g−1 respectively. Mean concentrations of metals followed this pattern: Zn > Se > Ni > Cu > Mn > Cd > Pb and Hg. We can conclude that blood is an excellent tissue to measure in relatively non-invasive way baseline values of heavy metals in Caretta caretta. 相似文献
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Assessment of persistent organochlorine pollutants in sediments from Lake Manzala, Egypt 总被引：2，自引：0，他引：2
Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in surface and core sediment samples collected from Manzala Lake, the largest of the Egyptian coastal lakes. Total concentrations of OCPs and ∑7 PCBs (ICES) in sediments ranged from 0.63 to 31.31 ng/g and 0.26 to 31.27 ng/g, respectively. Geographical distribution indicates that levels of contaminants were significantly higher in areas which are mainly influenced by municipal discharge, indicating significant sources of these compounds in urbanised areas. The composition of DDT and its metabolites suggest old input of DDT. The levels of contaminants in Manzala Lake were similar or lower than those observed in comparable areas worldwide. The profiles of ∑OCPs and ∑PCBs in a core from a site heavily impacted by sewage discharge have highest concentrations in the surface core section indicating recent inputs. Assessment of ecotoxicological risk indicated that sediments in two sites were likely to pose potential biological adverse impact. 相似文献
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Using GIS and perceived distance to understand the unequal geographies of healthcare in lower-income urban neighbourhoods 总被引：2，自引：0，他引：2
Geographers play important roles in public health research, particularly in understanding healthcare accessibility, utilisation, and individual healthcare experiences. Most accessibility studies have benefited from the increased sophistication of geographic information systems (GIS). Some studies have been enhanced with semi-structured in-depth interviews to understand individual experiences of people as they access healthcare. However, few accessibility studies have explicitly utilised individual in-depth interview data in the construction of new GIS accessibility measures. Using mixed methods including GIS analysis and individual data from semi-structured in-depth interviews, we offer satisfaction-adjusted distance as a new way of conceptualising accessibility in GIS. Based on fieldwork in a predominantly lower-income community in Columbus, Ohio (USA), we find many residents felt neighbourhood healthcare facilities offered low-quality care, which suggested an added perceived distance as they attempt to access high-quality healthcare facilities. The satisfaction-adjusted distance measure accounts for the perceived distance some residents feel as they search for high-quality healthcare in lower-income urban neighbourhoods. In moving beyond conventional GIS and re-conceptualising accessibility in this way, we offer a more realistic portrayal of the issues lower-income urban residents face as they attempt to access high-quality healthcare facilities. The work has theoretical implications for conceptualising healthcare accessibility, advances the mixed-methodologies literature, and argues for a more equitable distribution of high-quality healthcare in urban neighbourhoods. 相似文献
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1.引言美国国家气象中心(NMC)η模式计划的主要目的是研制能够提供北美地区中尺度预报指导的高分辨预报系统.根据几个月的每天两次的48小时预报和个例试验,结果证明模式具有相当大的潜力(Black和Mesinger,1989;Mesinger和Black,1989;Mesinger等,1990).作为重要预报变量的暴雨引起了特别的注意.精确预报它可能是最困难的. 相似文献
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李培忠 《矿物岩石地球化学通报》1992,(4)
80年代末以来,稳定同位素地球化学在实验技术和理论研究方面取得了长足的发展,主要表现在用激光技术加热分解样品供同位素分析测量和同位素分子配分函数比与分馏实验相结合推导新的同位素计温方程两方面。现将其简单介绍如下。 1.稳定同位素实验方法的革新传统的稳定同位素实验方法基本上都是采用对真空系统外加热方法(H同位素例外)使样品直接分解或与化学试剂作用产生气体供质谱分析的。这些方法有两大缺点,一是所需样品量大,特别是对于某些难于分选的试样,人们只好以全岩代替单矿物测定它们的同位素组成;二是样品分析时间长,例如用BrF_5法释放硅酸盐中氧的流程长达24小时(其中高温反应时间在10小时以上),磷酸分解碳酸盐法需在25℃下恒温24小时。这些条件不仅对水、电等环境因素提出了较高的要求,而且不利于快速分析样品。激 相似文献