Quantitative Analysis of Micro-structural Changes in a Bituminous Coal After Exposure to Supercritical CO2 and Water     

Zhang  Guanglei  Ranjith  P. G.  Perera  M. S. A.  Lu  Yiyu  Choi  Xavier 《Natural Resources Research》2019,28(4):1639-1660

Natural Resources Research - High-volatile bituminous coal samples were reacted in deionized water with supercritical CO2 (ScCO2–water) under simulated in situ pressure and temperature...  相似文献   

A Holistic Approach to Upwelling and Downwelling along the South-West Coast of India     

Phiros Shah  R. Sajeev  K. J. Thara  Grinson George  Muhammad Shafeeque  S. Akash 《Marine Geodesy》2019,42(1):64-84

An attempt has been made to develop a holistic understanding of upwelling and downwelling along the south-west coast of India. The main objective was to elucidate the roles of different forcings involved in the vertical motion along this coast. The south-west coast of India was characterized by upwelling during the south-west monsoon (May to September) and by downwelling during the north-east monsoon and winter (November to February). The average vertical velocity calculated along the south-west coast from the vertical shift of the 26?°C isotherm is 0.57?m/day during upwelling and 0.698?m/day during downwelling. It was concluded that upwelling along the south-west coast of India is driven by offshore Ekman transport due to the alongshore wind, Ekman pumping, horizontal divergence of currents and by the propagation of coastally trapped waves. Whereas downwelling along the coast is driven only by convergence of currents and the propagation of coastally trapped Kelvin waves. Along the west coast of India, the downwelling-favorable Kelvin waves come from the equator and upwelling-favorable waves come from the Gulf of Mannar region.  相似文献   

Long‐term temporal and spatial patterns in bioeroding sponge distribution at the Abrolhos Bank,Brazil, Southwestern Atlantic     

Fernando Coreixas de Moraes  Fernanda Cervi  Cludia S. Karez  Leonardo T. Salgado  Rodrigo L. Moura  Gabriella A. Leal  Alex C. Bastos  Gilberto M. Amado‐Filho 《Marine Ecology》2019,40(3)

Bioeroding sponges belong to the most dominant bioeroders, significantly contributing to the erosion of coral reefs. Some species are tolerant or even benefit from environmental conditions such as ocean warming, acidification, and eutrophication. In consequence, increases in sponge bioerosion have been observed on some coral reefs over the last decades. The Abrolhos Bank is the largest coral reef system in the South Atlantic. It has been affected by sedimentation, eutrophication, overfishing, and climate change, mainly affecting coastal reefs, and at lesser intensity outer ones as well. This study aimed to describe spatial and temporal patterns in bioeroding sponge distribution in carbonate substrates in the Abrolhos Bank. Photo‐quadrats were used to compare bioeroding sponge abundance between two shallow reefs: a coastal, Pedra de Leste (PL), and an outer reef, Parcel dos Abrolhos (PAB). Each individual was delimitated over the substrate by determining the sponge surface through a line connecting the outermost papillae. The study was conducted over 6 years in 2008–2009 and 2013–2016. Four species of bioeroding sponges were identified: Cliona carteri Ridley, 1881, C. delitrix Pang, 1973, C. cf. schmidtii Ridley, 1881, and Siphonodictyon coralliphagum Rützler, 1971. The distribution and abundance of species varied between the inner and outer reefs and across the years, and displayed certain selectivity for the calcareous substrates recorded. Crustose coralline algae (CCA) were the main substrate excavated by the most abundant bioeroding species, C. carteri, and represented 70% of the substrate types occupied by this sponge (CCA, coral overgrown by CCA and plain coral). The highest abundance of bioeroding sponges observed in photo‐quadrats was 21.3 individuals/m² at the outer reefs (PAB) in 2014. The abundances or areal extents of bioeroding sponges were up to 10 times greater on the outer reefs than on the coastal ones, where sedimentation is higher and more strongly influenced by siliciclastic material. Moreover, a higher herbivorous fish biomass has been reported on outer reefs which could also influence the higher abundance of bioeroding sponges in outer reefs. During the study period of 6 years, an increase in bioeroding sponge abundance was observed at the outer reefs (PAB), with the sea surface temperature increase. As CCA have an important role in reefal cementation and carbonate production in the Abrolhos reefs, a bioerosion impact might be expected, in particular, on the outer reefs.  相似文献   

Influx of Streaming Methane into Anoxic Waters of the Black Sea Basin     

Artemov  Yu. G.  Egorov  V. N.  Gulin  S. B. 《Oceanology》2019,59(6):860-870

Oceanology - Based on long-term data on the spatial distribution and fluxes of streaming (bubbling) methane in the Black Sea, the study considers various types of streaming gas emissions...  相似文献   

Analysis of soil drying incorporating a constitutive model for curling     

Maedo  Michael  Sánchez  Marcelo  Aljeznawi  Duaa  Manzoli  Osvaldo  Guimarães  Leonardo J. N.  Cleto  Pedro Rogério 《Acta Geotechnica》2020,15(9):2619-2635

This paper focuses on the shrinkage behavior of soil specimens involving sand, kaolinite, and kaolinite/sand mixtures subjected to desiccation under controlled conditions. Both, free and restrained shrinkage conditions are studied. The experiments show that pure soils do not curl upon unrestrained shrinkage; however, (under the same conditions) kaolinite/sand mixtures exhibited a marked curling. Furthermore, the mixture with the higher sand content broke through the middle of the sample after displaying a significant curling. Soils subjected to restricted shrinkage developed cracks with slight curling. To simulate the observed behavior, a mechanical model able to reproduce the detachment of the soil sample from the mold is proposed in this work and implemented in a fully coupled hydro-mechanical finite-element code. It is concluded that suction and differential shrinkage are key factors influencing the curling behavior of soils. The proposed framework was able to satisfactorily explain and reproduce the different stages and features of soil behavior observed in the experiments.

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Freshwater Sources in the Bays of Yuzhnyi Island of the Novaya Zemlya Archipelago According to Isotopic (δD, δ18O) Data     

Kossova  S. A.  Dubinina  E. O.  Chizhova  Ju. N.  Miroshnikov  A. Yu. 《Doklady Earth Sciences》2020,492(2):475-479

Doklady Earth Sciences - An isotope–geochemical study was performed on the waters of Abrosimov and Stepovoi bays along the southeastern coasts of the Novaya Zemlya Archipelago. The waters...  相似文献   

A Review on Marine N2 Fixation: Mechanism,Evolution of Methodologies,Rates, and Future Concerns     

Bhavya  P. S.  Min  Jun-Oh  Kim  Min-Seob  Jang  Hyo Keun  Kim  Kwanwoo  Kang  Jae Joong  Lee  Jae Hyung  Lee  Dabin  Jo  Naeun  Kim  Myung Joon  Kim  Yejin  Lee  Junbeom  Lee  Chang Hwa  Bae  Hyeonji  Yoo  Hyeju  Park  Sanghoon  Yun  Mi Sun  Lee  Sang Heon 《Ocean Science Journal》2019,54(4):515-528

Ocean Science Journal - Investigations on marine N2 fixation have gained momentum since 1960s with eventual establishments of relevant methodologies to identify species involved and quantify the...  相似文献   

Eurasian Large-Scale Hazes in Summer 2016     

Gorchakov  G. I.  Sitnov  S. A.  Karpov  A. V.  Gorchakova  I. A.  Gushchin  R. A.  Datsenko  O. I. 《Izvestiya Atmospheric and Oceanic Physics》2019,55(3):261-270

Izvestiya, Atmospheric and Oceanic Physics - The technique for constructing the spatial distribution of maximum aerosol optical depth (MAOD) has been used to estimate the optically dense haze...  相似文献   

New Orbit and Estimate of the Mass of the Star 61 Cygni Based on Observations of it in 1819-2019     

Izmailov  I. S.  Shakht  N. A.  Polyakov  E. V.  Gorshanov  D. L.  Pogodin  M. A. 《Astrophysics》2021,64(2):160-171

Astrophysics - This paper is a continuation of our earlier work devoted to determining the orbit and mass of the star 61 Cyg and the changes in the photometric characteristics of its components....  相似文献   

Sources of variability in springwater chemistry in Fool Creek,a high-elevation catchment of the Rocky Mountains,Colorado, USA     

Charles C. Rhoades  Timothy S. Fegel  Timothy P. Covino  Kathleen A. Dwire  Kelly Elder 《水文研究》2021,35(3):e14089

Springs are the point of origin for most headwater streams and are important regulators of their chemical composition. We analysed solute concentrations of water emerging from 57 springs within the 3 km² Fool Creek catchment at the Fraser Experimental Forest and considered sources of spatial variation among them and their influence on the chemical composition of downstream water. On average, calcium and acid neutralizing capacity (bicarbonate-ANC) comprised 50 and 90% of the cation and anion charge respectively, in both spring and stream water. Variation in inorganic chemical composition among springs reflected distinct groundwater sources and catchment geology. Springs emerging through glacial deposits in the upper portion of the catchment were the most dilute and similar to snowmelt, whereas lower elevation springs were more concentrated in cations and ANC. Water emerging from a handful of springs in a geologically faulted portion of the catchment were more concentrated than all others and had a predominant effect on downstream ion concentrations. Chemical similarity indicated that these springs were linked along surface and subsurface flowpaths. This survey shows that springwater chemistry is influenced at nested spatial scales including broad geologic conditions, elevational and spatial attributes and isolated local features. Our results highlight the role of overlapping factors on solute export from headwater catchments.  相似文献