Evaporation in Mediterranean conditions: Estimations based on isotopic approaches at the watershed scale     

Alexandra Mattei  Frédéric Huneau  Emilie Garel  Sébastien Santoni  Yuliya Vystavna 《水文研究》2021,35(5):e14085

In Mediterranean regions, the marked climatic seasonality and uneven precipitation distribution complicate the application of isotope mass balances to obtain meaningful basin-wide annual average evaporation rates. In the present study, a mass balance approach carried out on the Tavignanu River watershed in Corsica (France), showed unrealistic evaporation rate estimates: 10% for 2017–2018 and 1% for 2018–2019. This suggests that not only does evaporation alter the seasonal isotopic composition in the river, but that there is complex variability of the dominant water reservoirs contributing to the streamflow. Therefore, we propose a modified mass balance approach, including monthly quantifications of different water sources contributing to the river discharge. This allows the discrimination of isotopic variation occurring by evaporation from that originating by mixing processes. By applying this modified approach, we estimated evaporation rates on the Tavignanu River watershed that were in good agreement with results obtained by hydrological modelling: 40% for 2017–2018 and 46% for 2018–2019, respectively. An uncertainty analysis showed that evaporation rates obtained with the modified isotopic approach are close to those obtained with the non-modified approach. Therefore, we recommend using this modified isotope mass balance approach to estimate evaporation rates in such regions as the Mediterranean with high seasonality in hydrological processes.  相似文献   

Gully erosion reduces carbon and nitrogen storage and mineralization fluxes in a headwater catchment of south‐eastern Queensland,Australia          下载免费PDF全文

Alexandra Garzon‐Garcia  Jon M. Olley  Stuart E. Bunn  Philip Moody 《水文研究》2014,28(17):4669-4681

Increased erosion associated with land use change often alters the flux of sediments and nutrients, but few studies have looked at the interaction between these disrupted cycles. We studied the effects of gully erosion on carbon and nitrogen storage in surface soil/sediment and herbaceous vegetation and on C and N mineralization in a headwater catchment used for cattle grazing. We found significantly lower C and N stored in an incising gully compared with an intact valley. This storage was significantly higher in an adjacent stabilizing gully, although not to the levels found in the intact valley. The intact valley had two to four times higher soil/sediment concentrations of total organic C, total N and Colwell extractable P than the incising gully. Lower storage was not explained by differences in vegetation biomass density or silt and clay content. Vegetation accounted for only 8% of C and 2% of N storage. Although not a significant store in itself, vegetation has an important indirect role in restoring and maintaining soil/sediment C and N stocks in eroding areas. We found significant linear relationships between C and N mineralization rates and soil/sediment C and N content, with lower rates occurring in the eroded sediment. These findings support our initial hypothesis that gully erosion reduces C and N storage and mineralization rates in eroding catchments. The implications of this study include a change to the quality of eroded sediments in headwater catchments, causing C‐poorer and N‐poorer sediments to be exported but overall loads to increase. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Sedimentation of harmful dust by means of ultrasonic waves and additional disperse phase     

Sergey Titov  Maria Stepkina  Alexandra Antonnikova  Natalya Korovina  Boris Vorozhtsov  Eugeny Muravlev  Olga Kudryashova 《Arabian Journal of Geosciences》2015,8(12):11321-11328

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Guano-derived δ13C-based paleo-hydroclimate record from Gaura cu Musca Cave,SW Romania   总被引：1，自引：0，他引：1  

Bogdan P. Onac  Ferenc L. Forray  Jonathan G. Wynn  Alexandra M. Giurgiu 《Environmental Earth Sciences》2014,71(9):4061-4069

The δ¹³C values of 23 unevenly spaced guano samples from a 17-cm long clay sediment profile in Gaura cu Musc? Cave (GM), in SW Romania, made it possible to preliminarily characterize the Medieval Warm Period summer hydroclimate regime. The beginning of the sequence (AD 990) was rather wet for more than a century, before becoming progressively drier. After a brief, yet distinct wet period around AD 1170, drier conditions, with a possible shift from C₃ to a mixed C₃-dominated/C₄ type vegetation (2 ‰ lower δ¹³C values), prevailed for almost half a century before the climate became colder and wetter at the onset of the Little Ice Age, when bats left the cave. The guano-inferred wet and dry intervals from the GM Cave are mirrored by changes in the color and amount of clay accumulated in the cave. They also agree well with reconstructions based on pollen and charcoal from peat bogs and δ¹³C and δ¹⁸O on speleothems from other Romanian sites. Overall, these results indicate that the δ¹³C of bat guano can provide a sensitive record of the short-term coupling between local/regional climate and the plant–insect–bat–guano system.  相似文献   

Erratum to: Guano-derived δ13C-based paleo-hydroclimate record from Gaura cu Musca Cave,SW Romania     

Bogdan P. Onac  Ferenc L. Forray  Jonathan G. Wynn  Alexandra M. Giurgiu 《Environmental Earth Sciences》2014,71(9):4071-4071

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Radiochemoecological Monitoring of the Salt Lakes of the Crimea     

Natalya MIRZOYEVA  Sergey GULIN  Olga PLOTITSINA  Alexandra STETSUK  Svetlana ARKHIPOVA  Nina KORKISHKO  Oleg EREMIN 《《地质学报》英文版》2014,88(Z1):155-157

正1 Introduction The salt lakes of the Crimea contain the practically inexhaustible sources of salts of sodium,magnesium,bromine and other chemical elements(Ponizovskii,1965),being the potential powerful raw materials base for the  相似文献   

Perceptions of climate change: Linking local and global perceptions through a cultural knowledge approach     

Beatrice Crona  Amber Wutich  Alexandra Brewis  Meredith Gartin 《Climatic change》2013,119(2):519-531

Understanding public perceptions of climate change is fundamental to both climate science and policy because it defines local and global socio-political contexts within which policy makers and scientists operate. To date, most studies addressing climate change perceptions have been place-based. While such research is informative, comparative studies across sites are important for building generalized theory around why and how people understand and interpret climate change and associated risks. This paper presents a cross-sectional study from six different country contexts to illustrate a novel comparative approach to unraveling the complexities of local vs global perceptions around climate change. We extract and compare ‘cultural knowledge’ regarding climate change using the theory of ‘culture as consensus’. To demonstrate the value of this approach, we examine cross-national data to see if people within specific and diverse places share ideas about global climate change. Findings show that although data was collected using ethnographically derived items collected through place-based methods we still find evidence of a shared cultural model of climate change which spans the diverse sites in the six countries. Moreover, there are specific signs of climate change which appear to be recognized cross-culturally. In addition, results show that being female and having a higher education are both likely to have a positive effect on global cultural competency of individuals. We discuss these result in the context of literature on environmental perceptions and propose that people with higher education are more likely to share common perceptions about climate change across cultures and tentatively suggest that we appear to see the emergence of a ‘global’, cross-cultural mental model around climate change and its potential impacts which in itself is linked to higher education.  相似文献   

New soft gamma-ray bursts in the BATSE records and spectral properties of X-ray rich bursts     

Yana Tikhomirova  Boris E. Stern  Alexandra Kozyreva  Juri Poutanen 《Monthly notices of the Royal Astronomical Society》2006,367(4):1473-1477

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Luminescence chronology of non‐glacial sediments in Changeable Lake,Russian High Arctic,and implications for limited Eurasian ice‐sheet extent during the LGM     

Glenn W. Berger  Martin Melles  Debabrata Banerjee  Andrew S. Murray  Alexandra Raab 《第四纪科学杂志》2004,19(5):513-523

A 10.5 m core from Changeable Lake in the Severnaya Zemlya Archipelago just north of the Taymyr Peninsula intersects ca. 30 cm of diamicton at its base, interpreted as a basal till. Because the upper 10.13 m of this core consists of non‐glacial sediments, a maximum numeric age for these non‐glacial sediments would provide a clear lower limit to the timing of the last glaciation in the area of Changeable Lake. Radiocarbon (¹⁴C) dating of several materials from this core yielded widely scattered results. Consequently we applied photonic dating to sediments above the diamicton. The experimental single‐aliquot‐regenerative (SAR) dose fine‐grain method was applied to two samples, using the ‘double SAR’ approach. With one exception, these fine‐grain SAR results and the results of application of the SAR method to sand‐sized quartz grains from two samples, at ca. 9.95 m and ca. 10.05 m depth, are discrepant with age estimates from the multi‐aliquot infrared‐photon‐stimulated luminescence (IR‐PSL) method applied to fine grains. Multi‐aliquot IR‐PSL dating of 10 samples produces ages increasing monotonically from ca. 4 ka at 2 m to 53 ± 4 ka at 9.97 m. These self‐consistent multi‐aliquot IR‐PSL ages, along with limiting ¹⁴C ages of >47 ka at ca. 10 m, provide direct evidence that glacial ice did not advance over this lake basin during the Last Glacial Maximum, and thus delimit the northeastern margin of the Barents–Kara Sea ice‐sheet to somewhere west of this archipelago. The last regional glaciation probably occurred during marine isotope stage (MIS) 4 or earlier. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Electrodialytic treatment of sewage sludge: influence on microbiological community     

Paula Guedes  Nazaré Couto  Joana Almeida  António M. Rodrigues  Eduardo P. Mateus  Alexandra B. Ribeiro 《International Journal of Environmental Science and Technology》2018,15(5):1103-1112

This study aimed to evaluate the changes in microbiological communities present in sewage sludge (SS) when subjected to an electric field. The establishment of these relations is important to design and optimize an electrotechnology that not only promotes a direct degradation of the emerging organic contaminants, through electrodegradation, but also stimulates their biodegradation. Different current intensities were used continuously or by steps, in a two compartment electrodialytic (ED) cell. Samples collected between May and July of 2015 were analysed, prior to ED treatment, and the 35 Taxa identified were divided in 12 groups. Initial samples, collected on May, were mainly constituted by stalked ciliates (86%), followed by shelled amoebae (8%), whereas the samples collected between June and July presented higher number of shelled amoebae, between 52 and 92%. Epistylis, Vorticella and Arcella gibbosa were the most frequent protozoa identified. Samples richness (R) was between 7 and 14, Simpson’s biodiversity index (D) between 0.45 and 0.69, and evenness between 0.42 and 0.65. At the end of the ED experiments, a decrease in the number of identified Taxa and individuals was observed and, consequently, SS biodiversity also decreased. This decline was more pronounced in the ED experiments conducted with currents above 50 mA (0.10 mA cm^?2). In terms of abundance, the final SS was mainly constituted by shelled amoebae that showed to be the most resistant to the conditions within the ED cell. The obtained results showed that the studied conditions within the ED cell were not appropriate to the microbiological communities, which influenced the final SS quality.  相似文献