Dating the Lower Paleolithic Open-Air Site of Holon, Israel by Luminescence and ESR Techniques     

Naomi Porat  Li Ping Zhou  Michael Chazan  Tamar Noy  Liora Kolska Horwitz 《Quaternary Research》1999,51(3):328

The open-air Acheulian site in Holon, Israel, was dated by the luminescence methods and by electron spin resonance (ESR). Situated in the coastal plain Quaternary Kurkar Group, the Holon site was first excavated in the late 1960s, when typical lower Paleolithic lithics and middle Pleistocene fauna were found. In order to date the site, new test pits were dug adjacent to the earlier excavations and the archaeological bed was exposed in a section comprising a series of paleosols and aeolianites. Alkali feldspars separated from the sediments were dated using the infrared stimulated luminescence and thermoluminescence signals, and quartz was dated using the optically stimulated luminescence signal. The age of the archaeological bed is constrained by two samples to 198,000 ± 22,000–201,000 ± 17,000 yr. The age of the base of the section is 240,000 ± 29,000 yr, and the age of the top is 81,000 ± 8000 yr. Two teeth from the archaeological bed, recovered from the original excavation collection, yielded an average ESR age of 204,000 ± 16,000 yr, calculated using the linear uptake model, which is in a very good agreement with the luminescence ages. These dates place Holon within the range of other late Acheulian and Acheulo-Yabrudian sites in this region such as Tabun E (younger chronology), Yabrud I (archaeological level 18), and Berekhat Ram.  相似文献   

High frequency measurements of dissolved inorganic and organic nutrients using instrumented moorings in the southern and central North Sea     

Suhaimi Suratman  Keith Weston  Naomi Greenwood  David B. Sivyer  David J. Pearce  Tim Jickells 《Estuarine, Coastal and Shelf Science》2010

The aim of this study was to investigate the cycling of dissolved inorganic and organic nutrients using moored instrumented buoys (SmartBuoys) during the spring bloom in the North Sea. The instrumentation on the buoys enabled high frequency measurements of water-column integrated irradiance and in situ chlorophyll to be made, and also preserved water sample collection which were used for dissolved inorganic and organic nutrient analyses. The SmartBuoys were located in the year-round well-mixed plume zone associated with the River Thames and in the summer stratified central North Sea. These site locations allowed comparison of nutrient concentrations and cycling, and spring bloom development at two contrasting sites. The spring bloom was expected to be initiated at both stations due to increasing insolation and decreasing suspended load leading to higher water-column integrated irradiance. Due to differences in suspended load between the sites, the spring bloom started ∼2 months earlier in the central North Sea. The spring bloom in the Thames plume also resulted in higher maximum phytoplankton biomass due to the higher pre-bloom nutrient concentrations associated with riverine input. The use of SmartBuoys is also shown to allow the cycling of dissolved organic nutrients to be examined over the critical, and often undersampled, spring bloom period. Dissolved Organic Nitrogen (DON) clearly increased during the spring bloom in the central North Sea compared to winter concentrations. DON also increased in the Thames plume although showing greater winter variability related to higher riverine and sedimentary dissolved organic matter input at this shallow (∼18 m) coastal site. DON increase during the spring bloom was therefore related to primary production at both sites probably due to active release by phytoplankton. At both stations DON decreased to pre-bloom concentrations as the bloom declined suggesting the released DON was bioavailable and removed due to heterotrophic uptake and production. The preserved nutrient samples from the central North Sea site were also suitable for Dissolved Organic Phosphorus (DOP) analysis due to their low suspended load with similar trends and cycling to DON, albeit at lower concentrations. This suggested similar processes controlling both DON and DOP. The variable timing of short term events such as the spring bloom makes sampling away from coastal regions difficult without the use of autonomous technology. This study demonstrates for the first time the applicability of using preserved samples from automated buoys for the measurement of dissolved organic nutrients.  相似文献   

Dissolved and total organic and inorganic carbon in some British rivers   总被引：2，自引：0，他引：2  

Andy Baker  Sue Cumberland  Naomi Hudson 《Area》2008,40(1):117-127

Rivers transport both organic and inorganic carbon from their sources to the sea. Results of ~800 organic and inorganic analyses from various British rivers of contrasting size and land use are presented here: (1) the headwater River Tern, a rural river of 852 km² catchment; (2) the Ouseburn, a small urban 55 km² catchment; (3) the River Tyne, a larger river system of ~3000 km² catchment; (4) a spatial survey from 205 sample sites on ~60 rivers from SW England. We found that, with the exception of peat-rich headwaters, DIC concentration is always greater than DOC. DIC is primarily in the form HCO₃ ⁻ , with DIC concentrations highest in highly urbanised catchments, typically greater than those observed in catchments with carbonate bedrock, demonstrating a significant and previously unrecognised anthropogenic inorganic carbon input to urban rivers.  相似文献   

Environmental controls on modern chironomid faunas from NW Iceland and implications for reconstructing climate change   总被引：1，自引：1，他引：0  

Peter G. Langdon  Naomi Holmes  Chris J. Caseldine 《Journal of Paleolimnology》2008,40(1):273-293

Reconstructing climate change quantitatively over millennial timescales is crucial for understanding the processes that affect the climate system. One of the best methods for producing high resolution, low error, quantitative summer air temperature reconstructions is through chironomid analyses. We analysed over 50 lakes from NW and W Iceland covering a range of environmental gradients in order to test whether the distribution of the Icelandic chironomid fauna was driven by summer temperature, or whether other environmental factors were more dominant. A range of analyses showed the main environmental controls on chironomid communities to be substrate (identified through loss-on-ignition and carbon content) and mean July air temperature, although other factors such as lake depth and lake area were also important. The nature of the Icelandic landscape, with numerous volcanic centres (many of which are covered by ice caps) that produce large quantities of ash, means that relative lake carbon content and summer air temperature do not co-vary, as they often do in other chironomid datasets within the Arctic as well as more temperate environments. As the chironomid–environment relationships are thus different in Iceland compared to other chironomid training sets, we suggest that using an Icelandic model is most appropriate for reconstructing past environmental change from fossil Icelandic datasets. Analogue matching of Icelandic fossil chironomid datasets with the Icelandic training set and another European chironomid training set support this assertion. Analyses of a range of chironomid-inferred temperature transfer functions suggest the best to be a two component WA-PLS model with r ² _jack = 0.66 and RMSEP = 1.095°C. Using this model, chironomid-inferred temperature reconstructions of early Holocene Icelandic sequences show the magnitude of temperature change compared to contemporary temperatures to be similar to other NW European chironomid sequences, suggesting that the predictive power of the model is good.  相似文献   

Quantitative micro‐X‐ray fluorescence scanning spectroscopy of wet sediment based on the X‐ray absorption and emission theories: Its application to freshwater lake sedimentary sequences     

Nagayoshi Katsuta  Masao Takano  Naomi Sano  Yukinori Tani  Shinya Ochiai  Sayuri Naito  Takuma Murakami  Masakazu Niwa  Shin‐ichi Kawakami 《Sedimentology》2019,66(6):2490-2510

Micro‐X‐ray fluorescence scanning spectroscopy of marine and lake sedimentary sequences can provide detailed palaeoenvironmental records through element intensity proxy data. However, problems with the effects of interstitial pore water on the micro‐X‐ray fluorescence intensities have been pointed out. This is because the X‐ray fluorescence intensities are measured directly at the surfaces of split wet sediment core samples. This study developed a new method for correcting X‐ray fluorescence data to compensate for the effects of pore water using a scanning X‐ray analytical microscope. This involved simultaneous use of micro‐X‐ray fluorescence scanning spectroscopy and an X‐ray transmission detector. To evaluate the interstitial pore water content from the X‐ray transmission intensities, a fine‐grained sediment core retrieved from Lake Baikal (VER99‐G12) was used to prepare resin‐embedded samples with smooth surfaces and uniform thickness. Simple linear regression between the linear absorption coefficients of the samples and their porosity, based on the Lambert–Beer law, enabled calculation of the interstitial pore spaces and their resin content with high reproducibility. The X‐ray fluorescence intensities of resin‐embedded samples were reduced compared with those of dry sediment samples because of: (i) the X‐ray fluorescence absorption of resin within sediment; and (ii) the sediment dilution effects by resin. An improved micro‐X‐ray fluorescence correction equation based on X‐ray fluorescence emission theory considers the instrument's sensitivity to each element, which provides a reasonable explanation of these two effects. The resin‐corrected X‐ray fluorescence intensity was then successfully converted to elemental concentrations using simple linear regression between the data from micro‐X‐ray fluorescence scanning spectroscopy and from the conventional analyzer. In particular, the calculated concentration of SiO₂ over the depth of the core, reflecting diatom/biogenic silica concentration, was significantly changed by the calibrations, from a progressively decreasing trend to an increasing trend towards the top of the core.  相似文献   

Overestimation of short-term coastal cliff retreat rates in the eastern Mediterranean resolved with a sediment budget approach     

Amit Mushkin  Oded Katz  Naomi Porat 《地球表面变化过程与地形》2019,44(1):179-190

Our understanding of sea-cliff erosion processes and their response to recent and/or projected environmental changes such as sea-level rise, climate change and anthropogenic development hinges on our ability to quantify sea-cliff retreat rates and their variability through time. Here, we focus on Israel's Mediterranean ‘Sharon’ sea-cliff as a case study for examining the significance of recent short-term (i.e. annual to decadal) cliff-top retreat rates that appear to exceed longer-term rates of ‘background’ (i.e. centennial to millennial) retreat by 1–2 orders of magnitude. We demonstrate that an inherent sampling bias in rate estimates inferred from observation intervals shorter than process episodicity can also explain such a pattern. This potential ambiguity leads to a striking paradox where despite highly accurate and robust documentation of recent cliff-top retreat, such as that obtained from aerial photographs and/or instrumental surveys, the short-term retreat rates of episodically retreating sea cliffs remain poorly constrained. To address this key data gap along the Sharon sea cliff we employed a sediment budget approach that focuses on quantifying the continuous wave scouring of cliff-collapsed material from the shore platform as a rate-limiting process for episodic retreat of the cliff above. We used four high-resolution (0.5 m/pixel) airborne LiDAR data sets acquired between 2006 and 2015 to determine short-term maximum retreat rates of up to ~0.08 m/yr during this nine-year period. These modern retreat rates compare to the cliff's background retreat rate of 0.03 to 0.09 m/yr since the mid-Holocene, as determined herein from multiple geologic and archeological observations. Our results demonstrate that previously reported twentieth century cliff-top retreat rates for this sea cliff, which range up to values of several meters per year, are biased and that sea-cliff erosion rates have not yet been significantly impacted by recent environmental changes in the eastern Mediterranean basin, such as the restriction of sediment supply following emplacement of the Nile's Aswan dam system. © 2018 John Wiley & Sons, Ltd.  相似文献   

Using airborne thermal imaging data to measure near‐surface hydrology in upland ecosystems          下载免费PDF全文

David J. Luscombe  Karen Anderson  Naomi Gatis  Emilie Grand‐Clement  Richard E. Brazier 《水文研究》2015,29(6):1656-1668

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Spatial and temporal variability in nutrient concentrations in Liverpool Bay,a temperate latitude region of freshwater influence     

Naomi Greenwood  David J. Hydes  Claire Mahaffey  Andrew Wither  Jon Barry  David B. Sivyer  David J. Pearce  Susan E. Hartman  Olga Andres  Helen E. Lees 《Ocean Dynamics》2011,61(12):2181-2199

This paper presents data for the temporal and spatial distribution of nutrients in Liverpool Bay between 2003 and 2009 and an analysis of inputs of nutrients from the major rivers. The spatial distribution of winter nutrient concentrations are controlled by the region of freshwater influence (ROFI) in Liverpool Bay through the mixing of riverine freshwater and Irish Sea water, with strong linear relationships between nutrient concentration and salinity between December and February. The location of highest spring and summer phytoplankton biomass reflects the nutrient distributions as controlled by the ROFI. Analysis of 7 years of data showed that the seasonal cycle of winter maximum nutrient concentrations in February and drawdown in April/May is a recurrent feature of this location, with the timing of the drawdown varying by several weeks between years. A comparison of observed nutrient concentrations in Liverpool Bay with those predicted from inputs from rivers has been presented. Nutrient concentrations in the rivers flowing into Liverpool Bay were highly variable and there was reasonable agreement between predicted freshwater nutrient concentrations using data from this study and riverine nutrient concentrations weighted on the basis of river flow, although the exact nature of mixing between the rivers could not be determined. Predicted Irish Sea nutrient concentrations in the winter were lower than those reported for the input waters of the North Atlantic, supporting findings from previous work that nitrogen is lost through denitrification in the Irish Sea.  相似文献   

Effects of polychlorinated biphenyls on liver function and sexual characteristics in Japanese medaka (Oryzias latipes)     

Nakayama K  Sei N  Handoh IC  Shimasaki Y  Honjo T  Oshima Y 《Marine pollution bulletin》2011,63(5-12):366-369

The effects of polychlorinated biphenyls (PCBs) on liver function and their differences between sexes were analyzed in Japanese medaka (Oryzias latipes) exposed to PCB126 or Kanechlor-400 (KC-400) using microarray. PCB exposure induced vitellogenin 1 expression in female medaka while suppressing choriogenin genes, which suggests that the effects of PCBs on estrogen-responsive genes do not occur directly through an estrogen receptor-mediated pathway. Reduction of androgen receptor alpha expression was also observed, and the gene expression pattern in PCB-exposed males changed to become more similar to that of females. Furthermore, changes in glycolysis-related genes indicate that PCB exposure might enhance glucose production via gluconeogenesis in the liver of medaka. Taken together, our results suggest that PCBs disrupt the endocrine system, especially androgen function, and may have the potential to cause demasculinizing effects. Additionally, induction of gluconeogenesis might be a response to maintain glucose levels consumed as a result of PCB exposures.  相似文献   

Learning from the Pros: The Role of ISSRM,SNR, and IASNR in Our Careers     

Naomi Krogman  Carla Koons Trentelman  Joan Brehm  Courtney Flint 《社会与自然资源》2013,26(2):176-183

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