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241.
The water quality of rivers in the eastern part of the Humber Basin, north-eastern England is described from a baseflow survey (11–13 August 2006) of a wide range of water quality determinants, and long-term nutrient records of the Environment Agency of England and Wales (EA). The baseflow survey shows that the rivers are oversaturated with respect to dissolved CO2 and calcite. They are sodium, potassium, lithium, boron, chloride, sulphate and fluoride bearing from a combination of atmospheric, within-catchment, agricultural and sewage effluent sources. Nitrate concentrations are uniform for rivers draining permeable bedrock but decrease for clay drainage areas. Soluble reactive phosphorus (SRP) concentrations are variable across the catchments reflecting the importance and variability of point sources and within-river processing. The EA data show annual oscillations for both NO3 and SRP concentrations. Average NO3 concentrations vary between 3.3 and 18.8 mgN/l and concentrations are low during the summer months. Average SRP concentrations vary between 23 and 1959 μg/l. Highest SRP concentrations generally occur when there is effluent input from sewage treatment works and agricultural point sources (e.g. overflow from slurry tanks, farmyard washings). Despite many of the rivers being nutrient rich, they are generally of good biological quality when point source inputs are not important. 相似文献
242.
Margaret M. Krahn M. Bradley Hanson Candice K. Emmons Jennie L. Bolton Gina M. Ylitalo 《Marine pollution bulletin》2009,58(10):1522-10202
“Southern Resident” killer whales (Orcinus orca) that comprise three fish-eating “pods” (J, K and L) were listed as “endangered” in the US and Canada following a 20% population decline between 1996 and 2001. Blubber biopsy samples from Southern Resident juveniles had statistically higher concentrations of certain persistent organic pollutants than were found for adults. Most Southern Resident killer whales, including the four juveniles, exceeded the health-effects threshold for total PCBs in marine mammal blubber. Maternal transfer of contaminants to the juveniles during rapid development of their biological systems may put these young whales at greater risk than adults for adverse health effects (e.g., immune and endocrine system dysfunction). Pollutant ratios and field observations established that two of the pods (K- and L-pod) travel to California to forage. Nitrogen stable isotope values, supported by field observations, indicated possible changes in the diet of L-pod over the last decade. 相似文献
243.
Margaret E. Beck 《Geoarchaeology》2007,22(4):453-475
Middens are surprisingly fluid entities in occupied communities, as shown by ethnoarchaeological research in Dalupa, Kalinga Province, northern Luzon, the Philippines. This study combines ethnoarchaeological observations of midden formation and disturbance in Dalupa with data from soils and sediments in natural, habitation, and midden contexts, including elemental data for 80 samples collected using inductively coupled plasma‐atomic emission spectroscopy. Most surface samples from habitation areas cluster with midden samples, although samples from the lower parts of theses profiles resemble samples from natural contexts around Dalupa. One explanation is a changing spatial distribution of active middens due to changes in house placement and occupation in Dalupa's history. Some habitation areas that chemically resemble middens may once have held middens, as suggested by the periodic changes in midden location from the cleaning and management of extramural space. Surface scatters of human and animal refuse throughout the habitation area may also contribute to this pattern. © 2007 Wiley Periodicals, Inc. 相似文献
244.
Cytochrome P450 monooxygenases constitute an enzyme superfamily, with at least 74 known families. Members of CYP families 1–4 are important in the phase 1 metabolism of lipophilic xenobiotics, such as those found in contaminated marine environments. Previous studies (James et al. Arch. Biochem. Biophys. (1996) 329, 31–38) showed that a major form of P450 in spiny lobster, Panulirus argus, hepatopancreas was CYP2L1, a new sub-family, and that there was evidence for other P450 forms in hepatopancreas. We now report the sequence of a second member of this subfamily, named CYP2L2, present in P. Argus hepatopancreas. The deduced amino acid sequences of CYP2L1 and CYP2L2 share 54.7% sequence identity and an additional 13.6% of the sequences show conservative substitutions. Analysis of the sequences of CYP2L1, CYP2L2 and other representative CYP2 family members (from rat and mouse sub-families 2A, 2B, 2D and 2E) showed that the crustacean sequences clustered together. In addition to CYP2L2, cDNA clones of 66 to 117 base pairs from the 5′ coding region of two more P450 isoforms were isolated from the spiny lobster cDNA library. The deduced amino acid sequence of one of these additional cDNA clones was identical to the first 22 amino acids of the N-terminal sequence of a P450 protein previously isolated from hepatopancreas microsomes. These studies confirm earlier biochemical evidence that the hepatopancreas contains multiple forms of cytochrome P450. 相似文献
245.
土地资源约束下的北京食物供给潜力与优化(英文) 总被引:1,自引:1,他引:0
全球气候变化所带来的极端天气的频繁发生,水资源短缺情况下的农业用水的不断减少和伴随着人口增长与社会经济发展所引起的耕地面积下降,正在严重影响着世界范围内的食物安全。近年来由于食品价格的迅猛增长而导致的食品危机正在引起人们对增加地方食物供应的普遍关注。城市作为对食品安全更为敏感的地区,更是首当其冲受到食品危机的影响,城市一方面由于城市化快速发展,带来城市人口膨胀和消费多样性要求,从而形成需求的大幅增加,另一方面有由于城市周边耕地面积的不断减少,农业生产空间受到压缩,农业生产能力减弱,降低了城市的自我食品供给,引起自给率明显下降。如何保持供需之间的平衡,保障城市食品安全,成为亟需研究的问题。本文提出以食物足迹的概念,来衡量城市所间接消耗的土地资源,并以此为工具,以自给率为条件,来求得满足一定自给率条件下食物供给的空间对应格局。通过分析30年来北京食物足迹以及食物自给率的年际变化,得出结论:北京食物足迹从1981年的1.18万km2增加到2010年的2.94万km2,而自给率整体下降较多,蔬菜、水果、谷物及油脂类的自给率从1981年的59.3%、35.8%、37.3% 和 13.1% 下降到2010年的39.0%、27.0%、6.7% 和2.2%,可以看出蔬菜仍能保持相当的自给率,因此提高蔬菜自给率是增强城市自给能力的最佳选择。最后,以60%的蔬菜自给率为目标,提出了两种情景,包括完全以耕地为来源的空间应对格局,以及屋顶农业参与下的空间应对格局。 相似文献
246.
Toward a ground-motion logic tree for probabilistic seismic hazard assessment in Europe 总被引:9,自引:2,他引:7
Elise Delavaud Fabrice Cotton Sinan Akkar Frank Scherbaum Laurentiu Danciu Céline Beauval Stéphane Drouet John Douglas Roberto Basili M. Abdullah Sandikkaya Margaret Segou Ezio Faccioli Nikos Theodoulidis 《Journal of Seismology》2012,16(3):451-473
The Seismic Hazard Harmonization in Europe (SHARE) project, which began in June 2009, aims at establishing new standards for probabilistic seismic hazard assessment in the Euro-Mediterranean region. In this context, a logic tree for ground-motion prediction in Europe has been constructed. Ground-motion prediction equations (GMPEs) and weights have been determined so that the logic tree captures epistemic uncertainty in ground-motion prediction for six different tectonic regimes in Europe. Here we present the strategy that we adopted to build such a logic tree. This strategy has the particularity of combining two complementary and independent approaches: expert judgment and data testing. A set of six experts was asked to weight pre-selected GMPEs while the ability of these GMPEs to predict available data was evaluated with the method of Scherbaum et al. (Bull Seismol Soc Am 99:3234?C3247, 2009). Results of both approaches were taken into account to commonly select the smallest set of GMPEs to capture the uncertainty in ground-motion prediction in Europe. For stable continental regions, two models, both from eastern North America, have been selected for shields, and three GMPEs from active shallow crustal regions have been added for continental crust. For subduction zones, four models, all non-European, have been chosen. Finally, for active shallow crustal regions, we selected four models, each of them from a different host region but only two of them were kept for long periods. In most cases, a common agreement has been also reached for the weights. In case of divergence, a sensitivity analysis of the weights on the seismic hazard has been conducted, showing that once the GMPEs have been selected, the associated set of weights has a smaller influence on the hazard. 相似文献
247.
Heather Tallis Sarah E. LesterMary Ruckelshaus Mark PlummerKaren McLeod Anne GuerrySandy Andelman Margaret R. CaldwellMarc Conte Stephen CoppsDavid Fox Rod FujitaSteven D. Gaines Guy GelfenbaumBarry Gold Peter KareivaChoong-ki Kim Kai LeeMichael Papenfus Scott RedmanBrian Silliman Lisa WaingerCrow White 《Marine Policy》2012,36(1):303-306
Policies are arising around the world, most recently in the United States, that mandate the implementation of marine spatial planning as a practical pathway towards ecosystem-based management. In the new United States ocean policy, and several other cases around the globe, ecosystem services are at the core of marine spatial planning, but there is little guidance on how ecosystem services should be measured, making it hard to implement this new approach. A new framework is shown here for practical, rigorous ecosystem service measurement that highlights contributions from both natural and social systems. The novel three-step framework addresses traditional shortcomings of an ecosystem services approach by giving managers and scientists the tools to assess and track: (1) the condition of the ecosystem (supply metrics), (2) the amount of ocean resources actually used or enjoyed by people (service metrics), and (3) people's preference for that level of service (value metrics). This framework will allow real world progress on marine spatial planning to happen quickly, and with a greater chance for success. 相似文献
248.
249.
Mark S. Fonseca W. Judson Kenworthy Emily Griffith Margaret O. Hall Mark Finkbeiner Susan S. Bell 《Estuarine, Coastal and Shelf Science》2008
The scale of landscape pattern formation of an ecological community may provide clues as to the processes influencing its spatial and temporal dynamics. We conducted an examination of the spatial organization of an annual seagrass (Halophila decipiens) in an open ocean setting at two spatial scales and growing seasons to identify the relative influence of external (hurricanes) versus internal (clonal growth) factors. Visual surveys of seagrass cover were conducted over 2 years within three replicate 1 km2 study areas each separated by ∼25 km in an inshore–offshore transect along the southwest coast of Florida at depths between ∼10 and 30 m. A towed video sled allowed observations of seagrass cover of 1 m2 areas approximately every 6 m over thousands of meters of evenly spaced transects within the study areas (coarse scale). The towed video revealed that 17.5% of the seafloor was disturbed irrespective of location or sample time. Randomly selected 10 × 10 m quadrats within the larger, 1 km2 study areas were completely surveyed for seagrass cover by divers at 0.625 m2 resolution (fine scale). The coarse-scale observations were tested using both conventional geostatistics and an application of a time-series technique (Runs test) for scale of seagrass cover contiguity. Fine-scale observations were examined using conventional geostatistics and a least squares approach (cumulative logistic). 相似文献
250.
Jennifer J. Follstad Shah Ryan Bares Brenda B. Bowen Gabriel J. Bowen David R. Bowling David P. Eiriksson Benjamin Fasoli Richard P. Fiorella Anna Gannet Hallar Sarah J. Hinners John D. Horel Alexander A. Jacques Logan R. Jamison John C. Lin Daniel L. Mendoza Logan E. Mitchell Diane E. Pataki Sarah McKenzie Skiles Rose M. Smith Margaret A. Wolf Paul D. Brooks 《水文研究》2021,35(9):e14352
The 2085 km2 Jordan River Basin, and its seven sub-catchments draining the Central Wasatch Range immediately east of Salt Lake City, UT, are home to an array of hydrologic, atmospheric, climatic and chemical research infrastructure that collectively forms the Wasatch Environmental Observatory (WEO). WEO is geographically nested within a wildland to urban land-use gradient and built upon a strong foundation of over a century of discharge and climate records. A 2200 m gradient in elevation results in variable precipitation, temperature and vegetation patterns. Soil and subsurface structure reflect systematic variation in geology from granitic, intrusive to mixed sedimentary clastic across headwater catchments, all draining to the alluvial or colluvial sediments of the former Lake Bonneville. Winter snowfall and spring snowmelt control annual hydroclimate, rapid population growth dominates geographic change in lower elevations and urban gas and particle emissions contribute to episodes of severe air pollution in this closed-basin. Long-term hydroclimate observations across this diverse landscape provide the foundation for an expanding network of infrastructure in both montane and urban landscapes. Current infrastructure supports both basic and applied research in atmospheric chemistry, biogeochemistry, climate, ecology, hydrology, meteorology, resource management and urban redesign that is augmented through strong partnerships with cooperating agencies. These features allow WEO to serve as a unique natural laboratory for addressing research questions facing seasonally snow-covered, semi-arid regions in a rapidly changing world and an excellent facility for providing student education and research training. 相似文献