An altered carrying capacity of the Benguela upwelling ecosystem for African penguins (Spheniscus demersus)     

Crawford  Robert J. M.; Underhill  Les G.; Upfold  Leshia; Dyer  Bruce M. 《ICES Journal of Marine Science》2007,64(3):570-576

  相似文献   

Swimming endurance of haddock (Melanogrammus aeglefinus L.) at prolonged and sustained swimming speeds, and its role in their capture by towed fishing gears     

Breen  Mike; Dyson  Jamie; O'Neill  Finbarr G.; Jones  Emma; Haigh  Michael 《ICES Journal of Marine Science》2004,61(7):1071-1079

  相似文献   

Porites corals as recorders of mining and environmental impacts: Misima Island, Papua New Guinea   总被引：1，自引：0，他引：1  

Stewart J. Fallon  Jamie C. White†Malcolm T. McCulloch 《Geochimica et cosmochimica acta》2002,66(1):45-62

In 1989 open-cut gold mining commenced on Misima Island in Papua New Guinea (PNG). Open-cut mining by its nature causes a significant increase in sedimentation via the exposure of soils to the erosive forces of rain and runoff. This increased sedimentation affected the nearby fringing coral reef to varying degrees, ranging from coral mortality (smothering) to relatively minor short-term impacts. The sediment associated with the mining operation consists of weathered quartz feldspar, greenstone, and schist. These rocks have distinct chemical characteristics (rare earth element patterns and high abundances of manganese, zinc, and lead) and are entering the near-shore environment in considerably higher than normal concentrations. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we analyzed eight colonies (two from high sedimentation, two transitional, two minor, and two unaffected control sites) for Y, La, Ce, Mn, Zn, and Pb. All sites show low steady background levels prior to the commencement of mining in 1988. Subsequently, all sites apart from the control show dramatic increases of Y, La, and Ce associated with the increased sedimentation as well as rapid decreases following the cessation of mining. The elements Zn and Pb exhibit a different behavior, increasing in concentration after 1989 when ore processing began and one year after initial mining operations. Elevated levels of Zn and Pb in corals has continued well after the cessation of mining, indicating ongoing transport into the reef of these metals via sulfate-rich waters. Rare earth element (REE) abundance patterns measured in two corals show significant differences compared to Coral Sea seawater. The corals display enrichments in the light and middle REEs while the heavy REEs are depleted relative to the seawater pattern. This suggests that the nearshore seawater REE pattern is dominated by island sedimentation. Trace element abundances of Misima Island corals clearly record the dramatic changes in the environmental conditions at this site and provide a basis for identifying anthropogenic influences on corals reefs.  相似文献   

Aspects of the loss-on-ignition (LOI) technique in the context of clay-rich, glaciolacustrine sediments     

Jamie G. Smith 《Geografiska Annaler: Series A, Physical Geography》2003,85(1):91-97

The loss‐on‐ignition (LOI) technique for organic matter determination is evaluated with reference to clay‐rich, glaciolacustrine sediments. Examples of the use of LOI in glaciolacustrine literature are inconsistent in their methodology, and standardisation is called for. Problems with application of the technique to glaciolacustrine sediments stem mainly from the effects of additional weight loss due to release of structurally bound water and exposure time to ignition temperatures. Exposure time should be increased from 1 hour to 2.5 hours in the light of significant additional weight loss occurring between 2 and 2.5 hours in clay‐rich samples. The reason for this sudden increase in LOI after 2 hours (up to 86% of total LOI in some cases) appears to be the build‐up of a distinct surface crust during heating that insulates the core of the sample from ignition temperatures. Some time between 2 and 2.5 hours, the crust breaks down and exposes the sample core to ignition temperatures, increasing weight loss significantly. Overestimation of LOI due to loss of structural water is thought to be insignificant. Replicates of LOI at 550 and 1000°C in non‐calcareous, clay‐rich (>40%) sediments, show differences of <0.25%, which, for the purpose of inferring broad changes in glacier extent in lake catchments, is an acceptable error.  相似文献   

Considerations of Scale and Ecological Processes in a Forest Migration Model: A Reply to Roth     

James Dyer 《The Professional geographer》1996,48(1):86-88

  相似文献   

Alkylation of polycyclic aromatic hydrocarbons in carbonaceous chondrites     

Jamie E. Elsila  Peter R. Buseck 《Geochimica et cosmochimica acta》2005,69(5):1349-1357

Using microprobe laser-desorption, laser-ionization mass spectrometry (μL²MS), we measured the distributions of alkylated and unalkylated polycyclic aromatic hydrocarbons (PAHs) in the free organic material of 20 carbonaceous chondrites. These meteorites represent a variety of meteorite classes and alteration histories, including CI, CK, CM, CO, CR, CV, and Tagish Lake. This work provides information on free organic compounds that is complementary to studies of the structure and composition of meteoritic macromolecular content.For the nine CM2 meteorites analyzed, we observe that higher relative abundances of alkylated PAHs correlate with more intense aqueous activity. We attribute this correlation to the differences in solubility and volatility between unalkylated and alkylated PAHs. Naphthalene and its alkylation series are more susceptible to the effects of aqueous exposure than the less-soluble PAH phenanthrene and its alkylated derivatives. These observations are consistent with the possibility of chromatographic separations on the meteorite parent bodies. We identify six CM2 meteorites with similar PAH distributions that may represent the original, unaltered organic composition of the parent body.Increased metamorphic intensity reduces the abundance of all PAHs. The thermally metamorphosed CK chondrites had no detectable levels of typical meteoritic PAHs. This observation might be explained either by a loss of PAHs caused by volatilization or by a significantly different organic content of the CK parent body.  相似文献   

Dams on the Mekong River: Lost fish protein and the implications for land and water resources     

Stuart Orr  Jamie Pittock  Ashok Chapagain  David Dumaresq 《Global Environmental Change》2012,22(4):925-932

Proposed dam construction in the Lower Mekong Basin will considerably reduce fish catch and place heightened demands on the resources necessary to replace lost protein and calories. Additional land and water required to replace lost fish protein with livestock products are modelled using land and water footprint methods. Two main scenarios cover projections of these increased demands and enable the specific impact from the main stem dam proposals to be considered in the context of basin-wide hydropower development. Scenario 1 models 11 main stem dams and estimates a 4–7% increase overall in water use for food production, with much higher estimations for countries entirely within the Basin: Cambodia (29–64%) and Laos (12–24%). Land increases run to a 13–27% increase. In scenario 2, covering another 77 dams planned in the Basin by 2030 and reservoir fisheries, projections are much higher: 6–17% for water, and 19–63% for land. These are first estimates of impacts of dam development on fisheries and will be strongly mediated by cultural and economic factors. The results suggest that basic food security is potentially at a high risk of disruption and therefore basin stakeholders should be fully engaged in strategies to offset these impacts.  相似文献   

Editorial Introduction     

Gary Huckleberry  Jamie Woodward 《Geoarchaeology》2015,30(3):165-166

  相似文献   

The rich diversity of estuaries     

Keith Dyer 《Estuaries and Coasts》1990,13(4):504-505

  相似文献   

Kolmogoroff constants at the 1976 ITCE     

A. J. Dyer  B. B. Hicks 《Boundary-Layer Meteorology》1982,22(2):137-150

The high-frequency data from 12 sensors at the ITCE 1976^* are analysed to determine the Kolmogoroff constants for velocity, temperature and humidity fluctuation, _u , _T , and _q . The occurrence of aliasing in the spectral analysis in some cases together with the limited response of some sensors at the higher frequencies introduces some uncertainties into the analysis. The Soviet sonic anemometer, fine-wire thermometer and infrared hygrometer and the Australian infrared hygrometer provide the best information, namely that% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9qq-f0-yqaqVeLsFr0-vr% 0-vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHXoqyda% WgaaWcbaGaamyDaaqabaGccqGH9aqpcaaIWaGaaiOlaiaaiwdacaaI% 5aGaeyySaeRaaGimaiaac6cacaaIWaGaaGymaiaacYcacaqGGaGaae% iiaiaabccacaqGGaGaeqySde2aaSbaaSqaaiaadsfaaeqaaOGaeyyp% a0JaaGimaiaac6cacaaI2aGaaGioaiabgglaXkaaicdacaGGUaGaaG% imaiaaikdacaGGSaGaaeiiaiaabccacaqGGaGaaeiiaiabeg7aHnaa% BaaaleaacaWGXbaabeaakiabg2da9iaaicdacaGGUaGaaG4naiaaiA% dacqGHXcqScaaIWaGaaiOlaiaaicdacaaIZaaaaa!6248!\[\alpha _u = 0.59 \pm 0.01,{\text{ }}\alpha _T = 0.68 \pm 0.02,{\text{ }}\alpha _q = 0.76 \pm 0.03\]where the errors quoted refer solely to statistical errors. The other instruments provide general support to these values.The technique of using spectral density measurements to determine eddy fluxes is illustrated.International Turbulence Comparison Experiment.  相似文献