Geologically controlled bi-directional exchange of groundwater with a hypersaline lake in the Canadian prairies     

Laurence R. Bentley  Masaki Hayashi  Elena P. Zimmerman  Chris Holmden  Lynn I. Kelley 《Hydrogeology Journal》2016,24(4):877-892

Hypersaline lakes occur in hydrologically closed basins due to evaporitic enrichment of dissolved salts transported to the lakes by surface water and groundwater. At the hypersaline Lydden Lake in Saskatchewan, Canada, groundwater/lake-water interaction is strongly influenced by the geological heterogeneity of glacial deposits, whereby a highly permeable glaciofluvial sand/gravel deposit is underlain by glaciolacustrine deposits consisting of dense clay interspersed with silt/sand lenses. Pressure head distribution in a near shore area indicates a bi-directional flow system. It consists of topographically driven flow of fresh groundwater towards the lake in the sand/gravel aquifer and density-driven, landward flow of saline groundwater in the underlying glaciolacustrine deposits. Electrical resistivity tomography, and chemical and isotopic composition of groundwater clearly show the landward intrusion of saline water in the heterogeneous unit. The feasibility of bi-directional flow and transport is supported by numerical simulations of density-coupled groundwater flow and transport. The results suggest that the geologically controlled groundwater exchange processes have substantial influences on both inputs and outputs of dissolved minerals in hypersaline lakes in closed basins.  相似文献   

PCR‐based techniques to determine diet of the Australian sea lion (Neophoca cinerea): a comparison with morphological analysis          下载免费PDF全文

Kristian J. Peters  Kathy Ophelkeller    Herdina  Nathan J. Bott  Simon D. Goldsworthy 《Marine Ecology》2015,36(4):1428-1439

Comprehensive dietary information for the endangered Australian sea lion (Neophoca cinerea) is currently limited by the deficiency and poor quality of identifiable prey remains recovered from regurgitate and faeces and the difficulty of observing feeding in the wild. In this study, we investigated DNA‐based prey detection methods using conventional (end‐point) and quantitative real‐time PCR (qPCR) on faeces collected from two captive Australian sea lions fed experimental diets of whole teleost fish, squid and shark tissue. PCR prey detection methods using the mitochondrial cytochrome oxidase subunit I (COI) and 16S genes combined with clone sequencing were compared with prey identified using traditional hard part analysis. The molecular results indicated that prey DNA was degraded. However, prey amplification was successful by targeting short (71 bp) DNA fragments. Both conventional PCR and qPCR techniques significantly increased prey detection compared with analysis of hard parts. For both sea lions, the hard part analysis was constrained by sporadic and extremely low recovery of fish otoliths (<2%), and cephalopod beaks were not recovered from the 116 squid fed. Comparisons between PCR techniques indicated comparable prey detection frequencies for all species tested; however, the sensitivity and greater resolution of qPCR improved prey detection by ~25% in one sea lion fed the experimental squid and perch. The detection of squid DNA ≤ 6 day post‐ingestion by qPCR further exhibits the ability and potential of this method to detect low concentrations of infrequent or pulse prey. This study highlights the use of DNA‐based analysis to detect prey taxa in the absence of identifiable hard prey remains.  相似文献   

The use of soft X-ray spectromicroscopy to investigate the distribution and composition of organic matter in a diatom frustule and a biomimetic analog     

Lynn Abramson  Sue Wirick  Cindy Lee  Chris Jacobsen  Jay A. Brandes 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(18):1369-1380

Diatoms play a significant role in the global carbon cycle through their role in biogenic silica production and the transport of organic matter to the seafloor. Recent work has shown that silicified diatom frustules contain a significant amount of organic matter, and that the proportion of diatom-bound organic matter increases with depth in the water column and sediments. Here, we investigate the association between organic matter and the mineral phase. We used a combination of scanning transmission X-ray microscopy (STXM) and carbon X-ray absorption near-edge structure (XANES) spectroscopy to characterize the distribution and composition of organic matter in frustules of the diatom Cylindrotheca closterium and a biomimetic silica gel. To our knowledge, this study represents the first successful attempt to simultaneously image and obtain chemical information about the organic matter within a diatom frustule using X-ray spectromicroscopy near the carbon edge. Organic carbon, most likely protein, was distributed throughout the frustules and was not removed by harsh chemical treatment. The physical structure of the frustules appeared to be related to the chemical composition of this organic matter, with aromatic or unsaturated carbon being concentrated in the most intricately patterned regions of the frustule. A similar physical and chemical structure was observed in a biomimetic silica gel precipitated spontaneously with polylysine. These results are consistent with the theory that organic constituents of diatom frustules direct silica precipitation and become incorporated within the silica matrix as it forms. The relationship between organic matter composition and silica morphology, the failure of harsh chemical treatments to remove this organic matter, and the spontaneous nature of the co-precipitation of silica and organic matter indicate some chemical interaction between the siliceous and organic components of diatom frustules. Frustule-bound organic matter should therefore be protected from decomposition in the water column or diagenetic alteration in sediments unless the frustule dissolves.  相似文献   

A mini-review on the microbial continuum: consideration of a link between judicious consumption of a varied diet of macroalgae and human health and nutrition     

Cornish  M. Lynn  Mouritsen  Ole G.  Critchley  Alan T. 《中国海洋湖沼学报》2019,37(3):790-805

As the primordial, prokaryotic inhabitants on Earth, microbial entities were responsible for significant influences on the pathways taken in the development of life as we know it. The manifestation of numerous pathologies in humans is considered to be intrinsically associated with microbial dysbiosis in the gut(i.e. a poorly balanced microbiota). Such adverse health conditions include obesity, chronic fatigue syndrome, cancer, cardiovascular issues, neurological disorders, colitis, irritable bowel syndrome(IBS), and rheumatoid arthritis. Endosymbiotic events at the single cell level took place billions of years ago, eventually leading to eukaryotes, photosynthesis, and multicellularity. Macroalgae(seaweeds) were amongst the first organisms to develop these characteristics. Microbes and macroalgae interacted in a pattern of co-evolution,a process that applies to most, if not all living organisms. It is recognized that the normal human microbiome consists of over a trillion microorganisms, including about 2 000 commensal bacterial species typically stationed in the gut. Many of these live in the colon, where they function in the digestion of foods, releasing bio-available nutrients, bioactive molecules, and various metabolites. They mediate communication signals between the gut and the brain, and promote the normal development of immune function, metabolic activities, behaviour, and neurological stability. As very early humans foraged for food, some would have benefitted from coastal diets, rich in seaweeds and associated microbes. Such diets would have consistently provided all the nutrients essential for survival and growth, and as such, could have conveyed competitive advantages and contributed to enhanced cognitive sophistication. This mini-review article highlights studies regarding the health benefits of dietary fibres and the production of short chain fatty acids(SCFA). Insights are offered regarding the positive effects the inclusion of macroalgae into the standard, Western diet can deliver in terms of providing appropriate fodder for those microbial populations deemed beneficial to human health and wellness.  相似文献   

Preferential groundwater flow through a sorted net landscape,Arctic Canada     

Robert Hodgson  Kathy L. Young 《地球表面变化过程与地形》2001,26(3):319-328

Preferential suprapermafrost groundwater flow was observed in deepened channels lying between raised frost mounds. Here, saturated hydraulic conductivity, k, ranged from 90 to 1000 m/day but was only 0·1–1·0 m/day in the mound centres. A high proportion of fines occurs in the frost mound centre due to particle sorting, while channels contain gravels. Three approaches of areal weighting of k and groundwater flow, Q _s, across a wetland–upland boundary were explored. When percentage area covered by channels, mounds or gravel was considered, estimates of water flow on a daily and seasonal basis fell by 30 to 50 per cent. This study is of relevance to northern scientists who require reliable estimates of groundwater flow across patterned ground landscapes. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

A mini-review on the microbial continuum:consideration of a link between judicious consumption of a varied diet of macroalgae and human health and nutrition     

CORNISH M. Lynn  MOURITSEN Ole G.  CRITCHLEY Alan T. 《海洋湖沼学报（英文）》2019,(3):790-805

As the primordial,prokaryotic inhabitants on Earth,microbial entities were responsible for significant influences on the pathways taken in the development of life as we know it.The manifestation of numerous pathologies in humans is considered to be intrinsically associated with microbial dysbiosis in the gut(i.e.a poorly balanced microbiota).Such adverse health conditions include obesity,chronic fatigue syndrome,cancer,cardiovascular issues,neurological disorders,colitis,irritable bowel syndrome(IBS),and rheumatoid arthritis.Endosymbiotic events at the single cell level took place billions of years ago,eventually leading to eukaryotes,photosynthesis,and multicellularity.Macroalgae(seaweeds)were amongst the first organisms to develop these characteristics.Microbes and macroalgae interacted in a pattern of co-evolution,a process that applies to most,if not all living organisms.It is recognized that the normal human microbiome consists of over a trillion microorganisms,including about 2000 commensal bacterial species typically stationed in the gut.Many of these live in the colon,where they function in the digestion of foods,releasing bio-available nutrients,bioactive molecules,and various metabolites.They mediate communication signals between the gut and the brain,and promote the normal development of immune function,metabolic activities,behaviour,and neurological stability.As very early humans foraged for food,some would have benefi tted from coastal diets,rich in seaweeds and associated microbes.Such diets would have consistently provided all the nutrients essential for survival and growth,and as such,could have conveyed competitive advantages and contributed to enhanced cognitive sophistication.This mini-review article highlights studies regarding the health benefits of dietary fibres and the production of short chain fatty acids(SCFA).Insights are off ered regarding the positive effects the inclusion of macroalgae into the standard,Western diet can deliver in terms of providing appropriate fodder for those microbial populations deemed beneficial to human health and wellness.  相似文献   

SPIRITUAL PILGRIMS AT MOUNT SHASTA,CALIFORNIA*     

Lynn Huntsinger  María Fernndez‐Gimnez 《Geographical review》2000,90(4):536-558

ABSTRACT. Even the casual visitor cannot fail to notice unusual activity on the slopes of Northern California's Mount Shasta. Prayer flags, altars, and crystals are found in the meadows; drumming, chanting, and meditation are commonplace. Non‐indigenous spiritual pilgrims have found Mount Shasta a sacred place. An amorphous group of spiritual seekers, these are sometimes referred to as “New Age” adherents or “Crystal People.” Within the Shasta‐Trinity National Forest, the situation of this sacred site exemplifies the difficulties of reconciling nonsecular claims to public lands with secular management mandates. Spiritual activism at Mount Shasta includes recently successful opposition to development of a Forest Service‐endorsed ski area. Using a questionnaire survey and interviews, we compare the characteristics, activities, and attitudes toward resource management of spiritual pilgrims and others who visit Mount Shasta's meadows. Conclusions are drawn about the environmental values and concerns of all visitors and of spiritual pilgrims in particular, including some that bear on pilgrim activities and ecological restoration efforts.  相似文献   

Remote Observation of the Spatial Variability of Surface Waves Interacting With an Estuarine Outflow     

Brian K. Haus Rafael J. Ramos Hans C. Graber Lynn K. Shay Zachariah R. Hallock 《Oceanic Engineering, IEEE Journal of》2006,31(4):835-849

This paper explores the application of phased-array high-frequency (HF) radars to identify locations of enhanced local waveheights. Measurements of the near-surface current velocities and waveheights were obtained from HF radars deployed near the mouth of the Chesapeake Bay in the fall of 1997. The radar-derived near-surface velocities were compared with the upper bin (2-m depth) of four upward-looking acoustic Doppler current profilers (ADCPs). The slopes of the linear correlations were close to one and the root-mean-square (rms) differences were similar to previous studies. Significant waveheight (Hs) estimates from both radars were compared with a laser height gauge. The largest differences were observed during low winds due to overestimates at one of the radar stations and during storms when the laser measurement failed. Further analysis focused on the HF radar results from the more reliable of the two sites. The rms difference between this radar and the in situ sensor was 0.29 m. Synoptic observations of Hs over the Chesapeake Bay revealed regions of current-induced wave shoaling and refraction. Hs over the estuarine outflow increased between 19-50% relative to the incident Hs in light onshore winds (~5 m/s). In stronger winds (>10 m/s), Hs also increased by up to 25% when there was a tidal outflow in the surface layer, although the near-surface currents were responding to both the wind and the ebbing tide. Hs was not enhanced when the outflow was below a thicker layer (>5 m) of wind-forced onshore flow  相似文献   

A note on the Raman spectra of water-bearing albite glasses     

Paul F. McMillan  Sigurdur Jakobsson  John R. Holloway  Lynn A. Silver 《Geochimica et cosmochimica acta》1983,47(11):1937-1943

The Raman spectra of albite glasses with 4.5 and 6.6 weight percent water have been obtained, and are compared with that of a dry sample. The hydrous glasses show bands near 3600 cm^?1 due to O-H stretching, and a previously unreported weak band near 1600 cm^?1 due to bending of molecular H₂O. Other weak spectral features are discussed, and the effect of dissolved water on the aluminosilicate framework vibrations is considered.  相似文献   

Theory of the seismomagnetic effect: a reassessment     

Jin-Qi Hao  Lynn M. Hastie  Frank D. Stacey 《Physics of the Earth and Planetary Interiors》1982,28(2):129-140

Transient magnetic anomalies accompanying seismic stresses are more elusive than had been anticipated. We have, therefore, undertaken a more rigorous calculation than hitherto of the piezomagnetic effect accompanying representative seismic strain fields. We present a numerical method of treating faults of arbitrary area and orientation with fault displacement graded to zero at the fault boundaries to avoid stress discontinuities. The effect of grading the displacement in a realistic way is to give a more restricted and generally smaller piezomagnetic anomaly field than is indicated by simpler models. Seismomagnetism remains important in the search for earthquake prediction methods, but is more difficult to observe than had been hoped.  相似文献