PHYSIOLOGICAL INHIBITORY EFFECT OF OCS IN ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA （TREBOUXIOPHYCEAE, CHLOROPHYTA）   总被引：2，自引：0，他引：2  

刘建国  张成武ZviCohen AmosRichmond 《中国海洋湖沼学报》2002,20(3):248-255

Parietochloris incisa is an arachidonic acid-rich snow green alga. The main physiological profiles, such as ash free dry weight (AFDW), chlorophyll, carotenoid, protein and total fatty acids (TFA), in this alga exposed to old culture supernatant (OCS) at the decline phase or its crude ethyl acetate extracts (CEAE) were investigated by using tubular photobioreactors of different diameters. Results showed that both OCS and CEAE had strong inhibitory effect on the above physiological parameters. The longer the culture was exposed to OCS and the more CEAE were added into the algal culture, the more the above physiological properties were inhibited. Arachidonic acid (AA), the dominant component of fatty acids in this alga, was also seriously inhibited with respect to total TFA, AFDW of cell mass, or culture volume, due to a prebable reduction of enzymes activities catalyzing chain elongation from C18:1ω9 to AA. These results incontestably evidenced that some CEAE dissolving substances existing in OCS, like auto-inhibitors, inhibited P. incisa growth through feedback. Hence, any efficient removal of auto-inhibitors from algal culture to decrease their bioactivity could be good for maximal production of desired products like AA.  相似文献   

The Quaternary： its character and definition   总被引：5，自引：0，他引：5  

Martin J. Head Philip Gibbard Amos Salvador 《《幕》》2008,31(2):234-238

The Quaternary, is characterised by the development of widespread glaciations in mid-northern latitudes. As a chronostratigraphic term it has attracted vigorous debate. The Quaternao; as accepted by the International Union for Quaternary Research and proposed by the International Commission on Stratigraphy, begins at 2.6 Ma within a 2.8-2.4 Ma interval of profound change in Earth＇s climate system.  相似文献   

Sedimentology,depositional environments and significance of an Ediacaran salt‐withdrawal minibasin,Billy Springs Formation,Flinders Ranges,South Australia          下载免费PDF全文

John W. Counts  Kathryn J. Amos 《Sedimentology》2016,63(5):1084-1123

The late Ediacaran Billy Springs Formation is a little‐studied, mudstone‐dominated unit deposited in the Adelaide Rift Complex of South Australia. Sediments are exposed in an approximately 11 km × 15 km synclinal structure interpreted as a salt‐withdrawal minibasin. The stratigraphic succession is characterized by convolute‐laminated slump deposits, rhythmically laminated silty mudstones, rare diamictites and fining‐upward turbidite lithofacies. Lithofacies are the product of deposition in a deepwater slope or shelf setting, representing one of the few such examples preserved within the larger basin. Although exact correlations with other formations are unclear, the Billy Springs Formation probably represents the distal portion of a highstand systems tract, and is overlain by coarser sediments of the upper Pound Subgroup. Diamictite intervals are interpreted to be the product of mass flow processes originating from nearby emergent diapirs, in contrast to previous studies that suggest a glacial origin for extrabasinal clasts. Within the spectrum of outcropping minibasins around the world, the sediments described here are unique in their dominantly fine‐grained nature and overall lithological homogeneity. Exposures such as these provide an opportunity to better understand the sedimentological processes that operate in these environments, and provide an analogue for similar settings in the subsurface that act as hydrocarbon reservoir‐trap systems.  相似文献   

Integrated cave drip monitoring for epikarst recharge estimation in a dry Mediterranean area,Sif Cave,Israel     

Nathan A. Sheffer  Moty Cohen  Efrat Morin  Tamir Grodek  Alex Gimburg  Einat Magal  Haim Gvirtzman  Manuela Nied  Daniel Isele  Amos Frumkin 《水文研究》2011,25(18):2837-2845

Understanding recharge mechanisms and controls in karst regions is extremely important for managing water resources because of the dynamic nature of the system. The objective of this study was to evaluate water percolation through epikarst by monitoring water flow into a cave and conducting artificial irrigation and tracer experiments, at Sif Cave in Wadi Sussi, Israel from 2005 through 2007. The research is based on continuous high‐resolution direct measurements of both rainfall and water percolation in the cave chamber collected by three large PVC sheets which integrate drips from three different areas (17, 46, and 52 m²). Barrels equipped with pressure transducers record drip rate and volume for each of the three areas. The combined measured rainfall and cave data enables estimation of recharge into the epikarst and to better understand the relationship of rainfall‐recharge. Three distinct types of flow regimes were identified: (1) ‘Quick flow’ through preferential flow paths (large fractures and conduits); (2) ‘Intermediate flow’ through a secondary crack system; and (3) ‘Slow flow’ through the matrix. A threshold of ～100 mm of rain at the beginning of the rainy season is required to increase soil water content allowing later rainfall events to percolate deeper through the soil and to initiate dripping in the cave. During winter, as the soil water content rises, the lag time between a rain event and cave drip response decreases. Annual recharge (140–160 mm in different areas in the cave) measured represents 30–35% of annual rainfall (460 mm). Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

The COVID-19 pandemic and global environmental change: Emerging research needs     

Robert Barouki  Manolis Kogevinas  Karine Audouze  Kristine Belesova  Ake Bergman  Linda Birnbaum  Sandra Boekhold  Sebastien Denys  Celine Desseille  Elina Drakvik  Howard Frumkin  Jeanne Garric  Delphine Destoumieux-Garzon  Andrew Haines  Anke Huss  Genon Jensen  Spyros Karakitsios  Jana Klanova  Iida-Maria Koskela  Francine Laden  Paolo Vineis 《Chemie der Erde / Geochemistry》2010

The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

FATTY ACIDS PROFILE IN A HIGH CELL DENSITY CULTURE OF ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA （TREBOUXIOPHYCEAE, CHLOROPHYTA） EXPOSED TO HIGH PFD   总被引：1，自引：0，他引：1  

Liu Jian-guo  Zvi Cohen  Amos Richmond 《中国海洋湖沼学报》2002,20(2):149-156

The changes in arachidonic acid (AA) and fatty acids profiles along the growth curve ofParietochloris incisa, a coccoid snow green alga, were studied in a 2.8 cm light-path flat photobiorcactor, exposed to strong photon flux density [PFD, 2400 μEmol/(m²·s)]. Sixteen fatty acids were identified by gas chromatography showing that AA was the dominant fatty acid (33%–41%) followed by linoleic acid (17%–21%). AA content was closely investigated with respect to total fatty acids (TFA), ash free dry weight (AFDW) of cell mass as well as total culture content. These parameters were influenced significantly in a similar manner by culture growth phase, i.e., slightly decreasing in the lag period, gradually increasing in the logarithmic phase, becoming maximal at the early stationary phase, starting to decrease at the late stationary phase, sharply dropping at the decline phase. The increase in AA per culture volume during the logarithmic phase was not only associated with the increase in AFDW but also connected with a corresponding increase in AA/TFA, TFA/AFDW as well as AA/AFDW. The sharp decrease in AA content of the culture during the decline phase was mainly due to the decrease in AA/TFA, TFA/AFDW and AA/AFDW, although AFDW declined only a small extent. Maximal AA concentration, obtained at the early stationary phase, was 900 mg/L culture volume, and the average daily net increase of AA during 9 days logarithmic growth was 1.7 g/(m²·day). Therefore, harvesting prior to the decline phase in a batch culture, or at steady state in continuous culture mode seems best for high AA production. The latter possibility was also further confirmed by continuous culture with 5 gradients of harvesting rate. Contribution No. 4138 from the Institute of Oceanology, Chinese Academy of Sciences. Project 39970575 supported by NSFC and A/2786-2 supported by International Foundation for Sciences (IFS).  相似文献   

Using dissolved gas analysis to investigate the performance of an organic carbon permeable reactive barrier for the treatment of mine drainage     

R.L. Williams  K.U. Mayer  R.T. Amos  D.W. Blowes  C.J. Ptacek  J.G. Bain 《Applied Geochemistry》2007

The strongly reducing nature of permeable reactive barrier (PRB) treatment materials can lead to gas production, potentially resulting in the formation of gas bubbles and ebullition. Degassing in organic C based PRB systems due to the production of gases (primarily CO₂ and CH₄) is investigated using the depletion of naturally occurring non-reactive gases Ar and N₂, to identify, confirm, and quantify chemical and physical processes. Sampling and analysis of dissolved gases were performed at the Nickel Rim Mine Organic Carbon PRB, which was designed for the treatment of groundwater contaminated by low quality mine drainage characterized by slightly acidic pH, and elevated Fe(II) and SO₄ concentrations. A simple 4-gas degassing model was used to analyze the dissolved gas data, and the results indicate that SO₄ reduction is by far the dominant process of organic C consumption within the barrier. The data provided additional information to delineate rates of microbially mediated SO₄ reduction and confirm the presence of slow and fast flow zones within the barrier. Degassing was incorporated into multicomponent reactive transport simulations for the barrier and the simulations were successful in reproducing observed dissolved gas trends.  相似文献   

Late Quaternary environmental and human events at En Gedi, reflected by the geology and archaeology of the Moringa Cave (Dead Sea area, Israel)     

Sorin Lisker  Roi Porat  Hanan Eshel  Amos Frumkin 《Quaternary Research》2007,68(2):203-212

The Moringa Cave within Pleistocene sediments in the En Gedi area of the Dead Sea Fault Escarpment contains a sequence of various Pleistocene lacustrine deposits associated with higher-than-today lake levels at the Dead Sea basin. In addition it contains Chalcolithic remains and 5th century BC burials attributed to the Persian period, cemented and covered by Late Holocene travertine flowstone. These deposits represent a chain of Late Pleistocene and Holocene interconnected environmental and human events, echoing broader scale regional and global climate events. A major shift between depositional environments is associated with the rapid fall of Lake Lisan level during the latest Pleistocene. This exposed the sediments, providing for cave formation processes sometime between the latest Pleistocene (ca. 15 ka) and the Middle Holocene (ca. 4500 BC), eventually leading to human use of the cave. The Chalcolithic use of the cave can be related to a relatively moist desert environment, probably related to a shift in the location of the northern boundary of the Saharo-Arabian desert belt. The travertine layer was U-Th dated 2.46 ± 0.10 to 2.10 ± 0.04 ka, in agreement with the archaeological finds from the Persian period. Together with the inner consistency of the dating results, this strongly supports the reliability of the radiometric ages. The 2.46-2.10 ka travertine deposition within the presently dry cave suggests a higher recharge of the Judean Desert aquifer, correlative to a rising Dead Sea towards the end of the 1st millennium BC. This suggests a relatively moist local and regional climate facilitating human habitation of the desert.  相似文献   

Solar and anthropogenic imprints on Lake Masoko (southern Tanzania) during the last 500 years   总被引：1，自引：0，他引：1  

Yannick Garcin  David Williamson  Laurent Bergonzini  Olivier Radakovitch  Annie Vincens  Guillaume Buchet  Joël Guiot  Simon Brewer  Pierre-Etienne Mathé  Amos Majule 《Journal of Paleolimnology》2007,37(4):475-490

The Masoko crater-lake in southern Tanzania provides a continuous record of environmental changes covering the last 500 years. Multi-proxy studies were performed on a 52 cm sediment core retrieved from the deepest part of the lake. Magnetic, organic carbon, geochemical proxies and pollen assemblages indicate a dry climate during the ‘Little Ice Age’ (AD 1550–1850), confirming that the LIA in eastern Africa resulted in marked and synchronous hydrological changes. However, the direction of response varies between different African lakes (low versus high lake-levels), indicating strong regional contrasts that prevent the clear identification of climate trends over eastern Africa at this time. Inferred changes in Masoko lake-levels closely resemble the record of solar activity cycles, indicating a possible control of solar activity on the climate in this area. This observation supports previous results from East African lakes, and extends this relationship southward. Finally, anthropogenic impact is observed in the Masoko sediments during the last 60 years, suggesting that human disturbance significantly affected this remote basin during colonial and post-colonial times.  相似文献   

Seismotectonics of the Sinai subplate – the eastern Mediterranean region     

Amos Salamon  Avraham Hofstetter  Zvi Garfunkel  Hagai Ron 《Geophysical Journal International》2003,155(1):149-173

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