Fire,climate and the origins of agriculture: micro‐charcoal records of biomass burning during the last glacial–interglacial transition in Southwest Asia     

Rebecca Turner  Neil Roberts  Warren J. Eastwood  Emma Jenkins  Arlene Rosen 《第四纪科学杂志》2010,25(3):371-386

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High-frequency multi-solute calibration using an in situ UV–visible sensor     

Juan Pesántez  Christian Birkel  Giovanny M. Mosquera  Pablo Peña  Viviana Arízaga-Idrovo  Emma Mora  William H. McDowell  Patricio Crespo 《水文研究》2021,35(9):e14357

Monitoring the temporal variation of solute concentrations in streams at high temporal frequency can play an important role in understanding the hydrological and biogeochemical behaviour of catchments. UV–visible spectrometry is a relatively inexpensive and easily used tool to infer those concentrations in streams at high temporal resolution. However, it is not yet clear which solutes can be modelled with such an in-situ sensor. Here, we installed a UV–visible spectrometer probe (200–750 nm) in a high-altitude tropical Páramo stream to record the wavelength absorbance at a 5-min temporal resolution. For calibration, we simultaneously sampled stream water at a 4-h frequency from February 2018 to March 2019 for subsequent laboratory analysis. Absorbance spectra and laboratory-determined solute concentrations were used to identify the best calibration method and to determine which solute concentrations can be effectively inferred using in situ spectrometry through the evaluation of six calibration methods of different mathematical complexity. Based on the Nash – Sutcliffe efficiency (NSE) and Akaike information criterion metrics, our results suggest that multivariate methods always outperformed simpler strategies to infer solute concentrations. Eleven out of 21 studied solutes (Al, DOC, Ca, Cu, K, Mg, N, Na, Rb, Si and Sr) were successfully calibrated (NSE >0.50) and could be inferred using UV–visible spectrometry even with a reduced daily sampling frequency. It is worth noting that most calibrated solutes were correlated with wavelengths (WLs) in the low range of the spectra (i.e., UV range) and showed relatively good correlation with DOC. The latter suggests that estimation of metal concentrations could be possible in other streams with a high organic load (e.g., peat dominated catchments). In situ operation of spectrometers to monitor water quality parameters at high temporal frequency (sub-hourly) can enhance the protection of human water supplies and aquatic ecosystems as well as providing information for assessing catchment hydrological functioning.  相似文献   

The Multiscale TROPIcal CatchmentS critical zone observatory M-TROPICS dataset III: Hydro-geochemical monitoring of the Mule Hole catchment,south India     

Jean Riotte  Laurent Ruiz  Stéphane Audry  Benjamin Baud  Jean-Pierre Bedimo Bedimo  Laurie Boithias  Jean-Jacques Braun  Bernard Dupré  Jean-Louis Duprey  Mikael Faucheux  Christelle Lagane  Jean-Christophe Marechal  Hemanth Moger  Mandalagiri Subbarayappa Mohan Kumar  Harshad Parate  Olivier Ribolzi  Emma Rochelle-Newall  Buvaneshwari Sriramulu  Murari Varma  Muddu Sekhar 《水文研究》2021,35(5):e14196

Despite the importance of tropical ecosystems for climate regulation, biodiversity, water and nutrient cycles, only a few Critical Zone Observatories (CZOs) are located in the tropics. Among these, most are in humid climates, while very few data exist for semi-arid and sub-humid climates, due to the difficulty of estimating hydro-geochemical balances in catchments with ephemeral streams. We contribute to fill this gap by presenting a meteorological and hydro-geochemical dataset acquired at the Mule Hole catchment (4.1 km²), a pristine dry deciduous forest located in a biosphere reserve in south India. The dataset consists of time series of variables related to (i) meteorology, including rainfall, air temperature, relative humidity, wind speed and direction, and global radiation, (ii) hydrology, including water level and discharge at the catchment outlet, (iii) hydrogeology, including manual (monthly) and/or automated (from 15 min to hourly) groundwater levels in nine piezometers and (iv) geochemistry, including suspended sediment content in the stream and chemical composition of rainfall (event based), groundwater (monthly sampling) and stream water (storm events, 15 min to hourly frequency with an automatic sampler). The time series extend from 2003 to 2019. Measurement errors are minimized by frequent calibration of sensors and quality checks, both in the field and in the laboratory. Despite these precautions, several data gaps exist, due to occasional access restriction to the site and instrument destruction by wildlife. Results show that large seasonal and interannual variations of climatic conditions were reflected in the large variations of stream flow and groundwater recharge, as well as in water chemical composition. Notably, they reveal a long-term evolution of groundwater storage, suggesting hydrogeological cycles on a decadal scale. This dataset, alone or in combination with other data, has already allowed to better understand water and element cycling in tropical dry forests, and the role of forest diversity on biogeochemical cycles. As tropical ecosystems are underrepresented by Critical Zone Observatories, we expect this data note to be valuable for the global scientific community.  相似文献   

The effect of low‐permeability fault zones on groundwater flow in a compartmentalized system. Experimental evidence from a carbonate aquifer (Southern Italy)          下载免费PDF全文

Emma Petrella  Durante Aquino  Francesco Fiorillo  Fulvio Celico 《水文研究》2015,29(6):1577-1587

The hydrogeological behaviour of fault zones in carbonate aquifers is often neglected in conceptual and numerical models. Furthermore, no information is available regarding the relationships between piezometric levels when significant compartmentalization occurs due to the occurrence of low‐flow fault zones. The aim of this study was to refine the conceptualization of subsurface flow in faulted carbonate aquifers and to analyse relationships between sub‐basins within a compartmentalized aquifer system in Southern Italy. The interactions between compartments that straddle low‐flow faults were investigated over four hydrologic years using a statistical approach to compare (i) the hydraulic heads within two wells located up‐ and down‐gradient of tectonic discontinuities as well as (ii) the rainfall and piezometric levels. The results of this study suggest that a set of barriers exists between the wells, and, therefore, the total head loss observed between the wells (approximately 80 m) should be distributed across several aquitards, with one aquitard exhibiting a relatively high permeability or low degree of integrity. Due to slight differences in permeability, transient conditions in aquitards can occur over relatively short periods, which is in agreement with the results of the statistical data analysis. Consequently, rather than being caused by pure aquitards, aquifer system compartmentalization likely results from slight differences in the permeability between lower‐permeability fault zones and adjacent higher‐permeability protoliths. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

On judging the credibility of climate predictions     

Friederike E. L. Otto  Christopher A. T. Ferro  Thomas E. Fricker  Emma B. Suckling 《Climatic change》2015,132(1):47-60

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What do we know about UK household adaptation to climate change? A systematic review   总被引：1，自引：1，他引：0  

James J. Porter  Suraje Dessai  Emma L. Tompkins 《Climatic change》2014,127(2):371-379

The UK Government’s first National Adaptation Programme seeks to create a ‘climate-ready society’ capable of making well-informed and far-sighted decisions to address risks and opportunities posed by a changing climate, where individual households are expected to adapt when it is in their interest to do so. How, and to what extent, households are able to do this remains unclear. Like other developed countries, research on UK adaptation has focused predominately on public and private organisations. To fill that gap, a systematic literature review was conducted to understand what actions UK households have taken in response to, or in anticipation of, a changing climate; what drives or impedes these actions; and whether households will act autonomously. We found that UK households struggle to build long-term adaptive capacity and are reliant upon traditional reactive coping responses. Of concern is that these coping responses are less effective for some climate risks (e.g. flooding); cost more over the long-term; and fail to create household capacity to adapt to other stresses. While low-cost, low-skill coping responses were already being implemented, the adoption of more permanent physical measures, behavioural changes, and acceptance of new responsibilities are unlikely to happen autonomously without further financial or government support. If public policy on household adaptation to climate change is to be better informed than more high-quality empirical research is urgently needed.  相似文献   

The settling dynamics of flocculating mud-sand mixtures: Part 1��Empirical algorithm development     

Andrew James Manning  John V. Baugh  Jeremy R. Spearman  Emma L. Pidduck  Richard J. S. Whitehouse 《Ocean Dynamics》2011,61(2-3):311-350

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Paleogene carbon isotope excursions in the Bunkers Hill borehole: Hampshire Basin, UK     

Emma Hodgson  Stephen T. Grimes  Gregory D. Price  Meriel E.J. Fitzpatrick  Malcolm B. Hart  Melanie J. Leng 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(3):460-471

This study demonstrates that the Bunkers Hill borehole, which is located within the Hampshire Basin, contains a carbon isotope excursion (CIE) in the Upnor Formation followed by a positive recovery from another CIE within the overlying Reading Formation. This study has also shown that the CIE in the Upnor Formation predates the Paleocene/Eocene Thermal Maximum (PETM), while the carbon isotope recovery at the base of the Reading Formation is most likely related to it. The positive carbon isotope trend, before a return to more negative values, seen throughout the majority of the Reading Formation can also be seen in coeval deposits in the Jubilee 404T borehole in the London Basin and in the Tienen Formation in the Doel and Kallo boreholes from the Belgium Basin. This indicates that this post-PETM carbon isotope signal may, therefore, be regional if not global in nature.  相似文献   

Can shells of freshwater mussels (Unionidae) be used to estimate low summer discharge of rivers and associated droughts?     

Emma A. A. Versteegh  Hubert B. Vonhof  Simon R. Troelstra  Dick Kroon 《International Journal of Earth Sciences》2011,100(6):1423-1432

This paper examines if shell oxygen isotope ratios (δ¹⁸O_ar) of Unio sp. can be used as a proxy of past discharge of the river Meuse. The proxy was developed from a modern dataset for the reference time interval 1997–2007, which showed a logarithmic relationship between discharge and measured water oxygen isotope ratios (δ¹⁸O_w). To test this relationship for past time intervals, δ¹⁸O_ar values were measured in the aragonite of the growth increments of four Unio sp. shells; two from a relatively wet period and two from a very dry time interval (1910–1918 and 1969–1977, respectively). Shell δ¹⁸O_ar records were converted into δ¹⁸O_w values using existing water temperature records. Summer δ¹⁸O_w values, reconstructed from δ¹⁸O_ar of 1910–1918, showed a similar range as the summer δ¹⁸O_w values for the reference time interval 1997–2007, whilst summer reconstructed δ¹⁸O_w values for the time interval 1969–1977 were anomalously high. These high δ¹⁸O_w values suggest that the river Meuse experienced severe summer droughts during the latter time interval. δ¹⁸O_w values were then applied to calculate discharge values. It was attempted to estimate discharge from the reconstructed δ¹⁸O_w values using the logarithmic relationship between δ¹⁸O_w and discharge. A comparison of the calculated summer discharge results with observed discharge data showed that Meuse low-discharge events below a threshold value of 6 m³/s can be detected in the reconstructed δ¹⁸O_w records, but true quantification remains problematic.  相似文献   

The role of vegetation feedbacks on Greenland glaciation     

Emma J. Stone  Daniel J. Lunt 《Climate Dynamics》2013,40(11-12):2671-2686

The role of vegetation feedbacks for the process of ice-sheet evolution could potentially be important in realistically modeling the past and future evolution of the Greenland ice-sheet. We use a fully coupled atmosphere–ocean model to assess the response of the climate when the Greenland ice-sheet is replaced with a number of fixed vegetation types (bare soil, broadleaf and needleleaf trees, C3 and C4 grasses and shrubs) in conjunction with loaded and unloaded bedrock orography. These sensitivity experiments show that albedo changes dominate the climate response during the summer months while temperature changes during winter are attributed to altitude change and changes in atmospheric circulation over Greenland. Snow-free summers occur for all fixed vegetation types, except for high altitude eastern regions for bare soil. We perform further simulations with dynamic vegetation resulting in dominant shrub coverage over central and southern Greenland with grasses supported in the north. Ice-sheet modeling shows significant regrowth of the Greenland ice-sheet can occur for a bare soil surface type, dependent on ice-sheet model parameters, while Greenland remains almost ice-free for needleleaf tree coverage. Furthermore, a realistically vegetated Greenland can only support a small amount of ice-sheet regrowth implying multi-stability of the Greenland ice-sheet under a preindustrial climate. This study highlights the importance of considering vegetation climate ice-sheet interactions, and uncertainty in ice-sheet model parameters.  相似文献