A late paleo-Indian/Early archaic water well in Mexico—Possible oldest water-Management feature in the new world     

S. Christopher Caran  James A. Neely  Barbara M. Winsborough  Francisca Ramirez Sorensen  Salvatore Valastro 《Geoarchaeology》1996,11(1):1-35

A filled prehistoric water well discovered at the village of San Marcos Necoxtla, Puebla, Mexico, may be the oldest directly dated water-management feature in the Americas. The ∼10 m stratigraphic section exposed at this remarkable site records 18,000+ yr of deposition, erosion, water-table and hydrochemical fluctuations, and ≥10,000 yr of continual occupation. Temporal control is afforded by a multicomponent cultural chronology and radiocarbon assays by conventional and experimental techniques. The ∼10 m wide, ∼5 m deep well was excavated, utilized, maintained, and filled with cultural material between <9863 and ≫5950 yr B.P., a span of ≪3913 yr. Ages of other reported Late Pleistocene(?) to Middle Holocene wells in the New World are based on indirect or questionable dating, or are ≤6600 yr. Because of its age and continuity of occupation, the San Marcos Necoxtla well site may help define the nature of the peopling of the Americas and the advent of New World agriculture. © 1996 John Wiley & Sons, Inc.  相似文献   

Preface – Groundwater and microbial processes     

Barbara Bekins 《Hydrogeology Journal》2000,8(1):2-3

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Saturated areas through the lens: 2. Spatio-temporal variability of streamflow generation and its relationship with surface saturation     

Marta Antonelli  Barbara Glaser  Adriaan J. Teuling  Julian Klaus  Laurent Pfister 《水文研究》2020,34(6):1333-1349

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Examining the Extraction Efficiency of Petroleum-Derived Dissolved Organic Matter in Contaminated Groundwater Plumes     

Phoebe Zito  Rana Ghannam  Barbara A. Bekins  David C. Podgorski 《Ground Water Monitoring & Remediation》2019,39(4):25-31

The extraction efficiency of petroleum-derived dissolved organic matter (DOM) was examined for groundwater samples from an aquifer contaminated with crude oil. Five different types of extraction techniques were investigated to determine which method is best suited for the analysis of potentially toxic petroleum-derived DOM. The five types were a liquid-liquid extraction (LLE) with dichloromethane (DCM) and total petroleum hydrocarbons-diesel range (TPH_d) with DCM (EPA method 3510C), and three solid-phase extraction (SPE) stationary phases that are routinely used for extraction of polar analytes from water. For the LLE and TPH_d, that is selective for nonpolar compounds, the extraction efficiency of petroleum-derived DOM decreased downgradient as the petroleum-derived DOM becomes increasingly polar due to biodegradation. In contrast, the average extraction efficiency by the SPE methods was greater than 65% across the gradient. The results showed that SPE is more efficient for extracting petroleum-derived DOM at hydrocarbon-contaminated sites. The use of a method with greater extraction efficiency for partially oxidized hydrocarbons may prove useful in determining relationships between their composition and structure and potential for risks to human health or the environment.  相似文献   

Microbially Contaminated Water in Urban Fountains as a Hidden Source of Infections     

Barbara D. Modrzewska  Magdalena Bartnicka  Joanna Blaszkowska 《洁净——土壤、空气、水》2019,47(8)

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Central Asian aridification during the late Eocene to early Miocene inferred from preliminary study of shallow marine-eolian sedimentary rocks from northeastern Tajik Basin     

Xin Wang  Brian Kraatz  Jin Meng  Barbara Carrapa  Peter Decelles  Mark Clementz  Sherzod Abdulov  FaHu Chen 《中国科学:地球科学(英文版)》2016,59(6):1242-1257

The tempo-spatial development of the Cenozoic Asian aridification across the Eocene-Oligocene and its controlling factors are important scientific topics in Earth Sciences, which are pertinent to regional and global tectonic and climatic events. However, sedimentary rocks preserving the record of aridification during this time from central Asia (ACA) are rare. Here we present a preliminary analysis of sedimentary facies of the lower Paleogene in the northeastern Tajik Basin, which reveals that: the lower part of the studied section is dominated by shallow marine deposits of the Paratethys, the middle part is typical of alternations of eolian dune and fluvial deposits, the upper part is represented by eolian loess-sandy loess (L&SL) like facies, and the top exhibits alternations of fluvial-lacustrine and loess like facies. Based on a chronological framework derived from preliminary magnetostratigraphy, published U-Pb dating of a volcanic ash, and regional litho-stratigraphic correlations, we determine that eolian and L&SL facies accumulated in the northeastern Tajik Basin during the Late Eocene and through most of the Oligocene. These sedimentary units indicate that semi-arid to arid environments of ACA had developed at least since the late Eocene. This initial aridification is closely linked to the westward retreat of the Paratethys that was likely driven by a combination of tectonic activity and sea level changes.  相似文献   

Crude Oil Metabolites in Groundwater at Two Spill Sites          下载免费PDF全文

Barbara A. Bekins  Isabelle M. Cozzarelli  Melinda L. Erickson  Ross A. Steenson  Kevin A. Thorn 《Ground water》2016,54(5):681-691

Two groundwater plumes in north central Minnesota with residual crude oil sources have 20 to 50 mg/L of nonvolatile dissolved organic carbon (NVDOC). These values are over 10 times higher than benzene and two to three times higher than Diesel Range Organics in the same wells. On the basis of previous work, most of the NVDOC consists of partial transformation products from the crude oil. Monitoring data from 1988 to 2015 at one of the sites located near Bemidji, MN show that the plume of metabolites is expanding toward a lakeshore located 335 m from the source zone. Other mass balance studies of the site have demonstrated that the plume expansion is driven by the combined effect of continued presence of the residual crude oil source and depletion of the electron accepting capacity of solid phase iron oxide and hydroxides on the aquifer sediments. These plumes of metabolites are not covered by regulatory monitoring and reporting requirements in Minnesota and other states. Yet, a review of toxicology studies indicates that polar metabolites of crude oil may pose a risk to aquatic and mammalian species. Together the results suggest that at sites where residual sources are present, monitoring of NVDOC may be warranted to evaluate the fates of plumes of hydrocarbon transformation products.  相似文献   

Development of a Practical Tool for the Assessment of Biological Performances in Wastewater Treatment Plants          下载免费PDF全文

Francesca F. Malinverni  Barbara Ruffino 《洁净——土壤、空气、水》2016,44(11):1435-1443

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Assessment of the Global and Regional Land Hydrosphere and Its Impact on the Balance of the Geophysical Excitation Function of Polar Motion   总被引：2，自引：0，他引：2  

Małgorzata Wińska  Jolanta Nastula  Barbara Kołaczek 《Acta Geophysica》2016,64(1):270-292

The impact of continental hydrological loading from land water, snow and ice on polar motion excitation, calculated as hydrological angular momentum (HAM), is difficult to estimate, and not as much is known about it as about atmospheric angular momentum (AAM) and oceanic angular momentum (OAM). In this paper, regional hydrological excitations to polar motion are investigated using monthly terrestrial water storage data derived from the Gravity Recovery and Climate Experiment (GRACE) mission and from the five models of land hydrology. The results show that the areas where the variance shows large variability are similar for the different models of land hydrology and for the GRACE data. Areas which have a small amplitude on the maps make an important contribution to the global hydrological excitation function of polar motion. The comparison of geodetic residuals and global hydrological excitation functions of polar motion shows that none of the hydrological excitation has enough energy to significantly improve the agreement between the observed geodetic excitation and geophysical ones.  相似文献   

Climate and environment during the Younger Dryas (GS‐1) as reflected by composite stable isotope records of lacustrine carbonates at Torreberga,southern Sweden     

Dan Hammarlund  Thomas W. D. Edwards  Svante Bjrck  Bjrn Buchardt  Barbara Wohlfarth 《第四纪科学杂志》1999,14(1):17-28

Climatic and environmental changes during the Younger Dryas stadial (GS‐1) and preceding and following transitions are inferred from stable carbon and oxygen isotope records obtained from the sediments of ancient Lake Torreberga, southern Sweden. Event GS‐1 is represented in the sediment sequence by 3.5 m of clay containing lacustrine carbonates of various origins. Comparison of isotopic records obtained on mollusc shells, ostracod valves, and Chara encrustations precipitated during specific seasons of the year supports estimates of relative changes in both lake water and mean annual air temperatures. Variations in soil erosion rates can also be estimated from a simple isotope–mass‐balance model to separate allochthonous and autochthonous carbonate contributions to the bulk carbonate content of the sediments. The well‐known, rapid climatic shifts characterising the Last Termination in the North Atlantic region are clearly reflected in the isotopic data, as well as longer‐term changes within GS‐1. Following maximum cooling shortly after the Allerød–Younger Dryas (GI‐1–GS‐1) transition, a progressive warming and a slight increase in aquatic productivity is indicated. At the Younger Dryas–Preboreal (GS‐1–PB) transition mean annual air temperature rapidly increased by more than 5°C and summer lake‐water temperature increased by ca. 12°C. The subsequent Preboreal oscillation is characterised by an increase in soil erosion and a slight decrease in mean annual air temperature. These results are in harmony with recent findings about large‐scale climate dynamics during the Last Termination. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献