The Bolund Experiment,Part I: Flow Over a Steep,Three-Dimensional Hill   总被引：1，自引：0，他引：1  

J. Berg  J. Mann  A. Bechmann  M. S. Courtney  H. E. Jørgensen 《Boundary-Layer Meteorology》2011,141(2):219-243

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Benthic Superheroes: Living Foraminifera from Three Bays in the Mission-Aransas National Estuarine Research Reserve,USA     

Pamela Buzas-Stephens  Martin A. Buzas  Jonathan D. Price  Chandra Henry Courtney 《Estuaries and Coasts》2018,41(8):2368-2377

Studies of living foraminiferal assemblages provide much information about their roles in present environments and a perspective on interpreting the past. Along modern coasts, benthic Foraminifera act as ecological indicators in their responses to different natural and anthropogenic conditions, such as food availability, oxygen concentrations, salinity, and trace metal concentrations. A detailed survey of foraminiferal populations was undertaken in the Mission-Aransas National Estuarine Research Reserve, Texas, close to the time of its establishment in 2006. The purpose was to gauge the overall status of populations and provide baseline data for future comparison. The arid south Texas Gulf Coast is a variable and often harsh environment where biota are subject to multiple anthropogenic stressors. Despite these rigors, living Foraminifera were prolific in the Reserve. This paper discusses the results from Mesquite (July 2008), Copano (May 2006), and Mission Bays (June 2006). Populations were robust in each bay, with Ammonia parkinsoniana, Ammotium salsum, and Elphidium excavatum being most abundant. Highest numbers corresponded mainly to areas of greater circulation. In Mission Bay, elemental analysis of shells, prompted by the presence of sulfur grains in sediments and by yellow tests, detected elevated levels of barium, strontium, and iron. Most sediment samples were black and sulfidic, and ubiquitous framboidal pyrite in sediment and shells suggests that forams were frequently subject to low-oxygen conditions. Abundant living numbers, tolerance of low-oxygen conditions, and the ability to cycle trace metals emphasize the resilience of Foraminifera in taxing environments and their integral position as lower trophic level members.  相似文献   

Investigating the association between streetscapes and human walking activities using Google Street View and human trajectory data   总被引：1，自引：0，他引：1       下载免费PDF全文

Xiaojiang Li  Paolo Santi  Theodore K. Courtney  Santosh K. Verma  Carlo Ratti 《Transactions in GIS》2018,22(4):1029-1044

Having an active lifestyle is recognized to positively contribute to public health. Creating more walkable streets and neighborhoods is an important way to promote an active lifestyle for urban residents. It is therefore important to understand how the urban built environment can influence human walking activities. In this study, we investigated the interaction of human walking activities and physical characteristics of streetscapes in Boston. A large number of anonymous pedestrian trajectories collected from a smartphone application were used to estimate human walking activities. Publicly accessible Google Street View images were used to estimate the amount of street greenery and the enclosure of street canyons, both of which were used to indicate the physical characteristics of streetscapes. The Walk Score and population were also added in the statistical analyses to control the influence of nearby urban facilities and population on human walking activities. Statistical analysis results show that both the street greenery and the enclosure of the street canyons are significantly associated with human walking activities. The associations between the streetscape variables and human walking activities vary in different land use types. The results of this study have implications for designing walkable and healthy cities.  相似文献   

Synchronous changes in chironomid assemblages in two Arctic delta lake ecosystems after a major saltwater intrusion event     

Joshua R. Thienpont  Courtney Steele  Jesse C. Vermaire  Michael F. J. Pisaric  Steven V. Kokelj  John P. Smol 《Journal of Paleolimnology》2015,53(2):177-189

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Holocene climate–fire–vegetation interactions at a subalpine watershed in southeastern British Columbia,Canada     

Colin J. Courtney Mustaphi  Michael F.J. Pisaric 《Quaternary Research》2014

Vegetation assemblages and associated disturbance regimes are spatially heterogeneous in mountain ecosystems throughout the world due to the complex terrain and strong environmental gradients. Given this complexity, numerous sites describing postglacial vegetation and fire histories are needed to adequately understand forest development and ecosystem responses to varying climate and disturbance regimes. To gain insight into long-term historical climate–fire–vegetation interactions in southeastern British Columbia, Canada, sedimentological and paleoecological analyses were performed on a sediment core recovered from a small subalpine lake. The pollen assemblages, stomata, and macroremains indicate that from 9500 to 7500 cal yr BP, Pinus-dominated forests occurred within the catchment and Alnus was also present. Climate was an important control of fire and fire frequency was highest at this time, peaking at 8 fires 1000 yr^− 1, yet charcoal accumulation rates were low, indicative of low terrestrial biomass abundance. From 7500 to 4600 cal yr BP, Pinus decreased as Picea, Abies and Larix increased and fire frequencies decreased to 3–6 fires 1000 yr^− 1. Since 7500 cal yr BP the fire regime varied at a millennial scale, driven by forest biomass abundance and fuel accumulation changes. Local scale (bottom-up) controls of fire increased in relative importance since at least 6000 cal yr BP.  相似文献   

Deposition of 1.88-billion-year-old Iron Formations as a Consequence of Rapid Crustal Growth     

Birger Rasmussen  Ian R. Fletcher  Andrey Bekker  Janet R. Muhling  Courtney J. Gregory  Alan M. Thorne 《Journal of the Geological Society of India》2012,80(1):147

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A strategy for detecting derelict fishing gear at sea     

McElwee K  Donohue MJ  Courtney CA  Morishige C  Rivera-Vicente A 《Marine pollution bulletin》2012,65(1-3):7-15

Derelict fishing gear (DFG) is a highly persistent form of marine pollution known to cause environmental and economic damage. At-sea detection of DFG would support pelagic removal of this gear to prevent and minimize impacts on marine environments and species. In 2008, experts in marine debris, oceanography, remote sensing, and marine policy outlined a strategy to develop the capability to detect and ultimately remove DFG from the open ocean. The strategy includes three interrelated components: understanding the characteristics of the targeted DFG, indirectly detecting DFG by modeling likely locations, and directly detecting pelagic DFG using remote sensing. Together, these components aim to refine the search area, increase the likelihood of detection, and decrease mitigation response time, thereby providing guidance for removal operations. Here, we present this at-sea detection strategy, relate it to relevant extant research and technology, and identify gaps that currently prevent successful at-sea detection and removal of DFG.  相似文献   

Dietary pattern recognition on Twitter: a case example of before,during, and after four natural disasters     

Turner-McGrievy  Gabrielle  Karami  Amir  Monroe  Courtney  Brandt  Heather M. 《Natural Hazards》2020,103(1):1035-1049

Natural Hazards - Little is known about what foods/beverages (F&B) are common during natural disasters. The goal of this study was to track high-frequency F&B mentions during four...  相似文献   

A note on the relocation of marsh debris during a storm surge     

Courtney T. Hackney  T. Dale Bishop 《Estuarine, Coastal and Shelf Science》1981,12(5):621-624

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Microbial dynamics in cyclonic and anticyclonic mode-water eddies in the northwestern Sargasso Sea     

Courtney S. Ewart  Meredith K. Meyers  Elisa R. Wallner  Dennis J. McGillicuddy Jr.  Craig A. Carlson   《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(10-13):1334

The EDdy Dynamics, mixing, Export, and Species composition (EDDIES) project provided a unique opportunity to evaluate the response of the microbial community and further understand the biological and biogeochemical consequences of mesoscale perturbation events in an oligotrophic system. In order to characterize microbial dynamics, we performed measurements of bacterial biomass (BB) and production (BP) and phytoplankton pigment analyses in two upwelling eddies in the Sargasso Sea sampled in 2004 and 2005. We also observed a 3-fold increase in BP at the Bermuda Atlantic Time-series Study (BATS) site during the passage of a cyclonic eddy in 2003. Although the integrated BB and BP over 140 m in 2004 and 2005 eddies remained within the climatological range measured at the BATS site, there was systematic variability in bacterioplankton dynamics across both eddies. Cyclonic eddy C1 demonstrated decreased BP at the feature's center relative to its periphery, and BP was not correlated with total chlorophyll a (TChl a) variability. However, BP correlated with prymnesiophyte pigments throughout the feature. In contrast, mode-water eddy A4 showed an enhancement in BP at the eddy center (EC) relative to its edges and was coincident with elevated TChl a, high primary production measurements, and a high concentration of diatoms. In eddy A4, the tight relationship between enhanced BP, TChl a and specific phytoplankton taxa implies that the phytoplankton community structure was an important factor influencing BP variability. While the heterotrophic bacterial response in C1 and A4 was not enhanced relative to BATS summer climatology, these data and the presence of similar nutrient fields across both eddies suggest that BP and BB were influenced by the eddy perturbations and responded to changes in the phytoplankton community.  相似文献