scholarly journals Influence of diagenetic processes and terrestrial/anthropogenic sources in the REE contents of the Cascais submarine canyon (Iberian western coast)

2021 ◽  
Vol 773 ◽  
pp. 145539
Author(s):  
Mário Mil-Homens ◽  
Pedro Brito ◽  
Miguel Caetano ◽  
Ana Maria Costa ◽  
Susana Lebreiro ◽  
...  
Keyword(s):  
Submarine Canyon ◽  
Anthropogenic Sources ◽  
Western Coast ◽  
Diagenetic Processes

scholarly journals Flocculation of dissolved organic matter controls the distribution of iron in boreal estuarine sediments

2017 ◽  
Author(s):  
Tom Jilbert ◽  
Eero Asmala ◽  
Christian Schröder ◽  
Rosa Tiihonen ◽  
Jukka-Pekka Myllykangas ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Particulate Material ◽  
Estuarine Sediments ◽  
Anthropogenic Sources ◽  
Diagenetic Processes ◽  
Fe Content ◽  
Estuarine Zone ◽  
Organic Matter Pool ◽  
Boreal River

Abstract. Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM). However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation of DOM along salinity gradients in an estuary of the northern Baltic Sea efficiently transfers Fe from the dissolved phase into particulate material that accumulates in the sediments. Consequently, we observe a decline with distance offshore in both the Fe content of the sediments and proportion of terrestrial material in the sedimentary organic matter pool. Mössbauer spectroscopy and sequential extractions suggest that large amounts of Fe in sediments of the upper estuarine zone are associated with organic matter as unsulfidized Fe (II) complexes, or present in the form of ferrihydrite, implying a direct transfer of flocculated material to the sediments. Accordingly, the contribution of these components to the total sedimentary Fe declines with distance offshore while other Fe phases become proportionally more important. Sediment core records show that the observed lateral distribution of Fe minerals has remained similar over recent decades, despite variable Fe inputs from anthropogenic sources and eutrophication of the coastal zone. Pore water data suggest that the vertical zonation of diagenetic processes in the sediments is influenced by both the availability of Fe and by bottom water salinity, which controls the availability of sulfate (SO42−).

Terrestrial Submarine Discontinuous Systems as Analogs for Similar Martian Channel Morphologies.

2020 ◽  
Author(s):  
Mohamed Amine Ettahri
Keyword(s):  
Continental Shelf ◽  
Preliminary Investigation ◽  
Drainage System ◽  
River System ◽  
Submarine Canyon ◽  
Large River ◽  
Western Coast ◽  
Drainage Systems ◽  
Western Sahara ◽  
Continental Shelves

<p>   Channel systems on both Earth and Mars present several morphological similarities suggesting that they are the results of relatively similar mechanisms in the spatial and temporal contexts. Our research focuses on investigating discontinuous channels, morphologically defined as channel segments interrupted by unchanneled reaches or as a set of streams interrupted over space. These systems are unfrequently found on Mars or Earth [1], therefore signify an indication of special topographic, hydrologic or lithologic conditions.</p><p>   A draft classification takes into account that discontinuities can be classified into major groups according to their origin and geological setting: 1) Arid region discontinuities. 2) Sinking streams in lava and karsts terrains. 3) Fluvio-lacustrine, continental shelves, and deep-sea discontinuities. 4) Other types as post fluvial effects that obliterate channel sections by impact cratering, Sediment covers, mudflows intersecting and filling in the channel in addition to the selective channel material removal.</p><p>   We characterized such drainage systems on Mars, in the Navua Valles paleo drainage system [2], and near Saheki crater, both situated in the northern flank of Hellas Basin. While on Earth, we identified a number of similar settings as analogs to those identified on Mars, in arid regions such as in Mojave river (USA), and the Sahara Desert (Algeria).</p><p>   Furthermore, an unusual type of martian analog on Earth was identified in the subsea using bathymetric maps, as we located discontinuous segments in various continental shelf locations to the western coast of North America [3] and to the northwest African margin in Mauritania [4]. Our preliminary investigation suggests that discontinuous channel morphologies in terrestrial dryland may be similar to those in the seafloor on a larger scale.</p><p>   The West African continental shelf confines a discontinuity in the paleo drainage rivers system flowing from the Tamanrasset paleo drainage river to Cap Timiris submarine canyon system [4]. That unmapped channel segments are believed to occur due to the change of kinetic energy on the sea bottom at relatively less sloping, then the channels reappear at the edge of continental shelves as a result of slope change. The topographic profile of a selected site southeast to Saheki crater on Mars manifested a similar topography to a continental shelf- submarine canyon system. The martian site is suggested to be a paleolake.</p><p>   As a preliminary result of our study, we emphasize that the discontinuous behavior of submarine channels on terrestrial continental shelves might be a relevant analog for understanding similar martian drainage systems and further expand geomorphological studies for a new branch of martian-terrestrial analogs in the subsea.</p><p>References:</p><p>[1] Hargitai H. et al. 2017. Discontinuous Drainage Systems Formed by Precipitation and Ground-Water Outflow in the Navua Valles and Southwest Hadriacus Mons, Mars. [2] Ettahri M.A & Hargtiai H. 2019. Discontinuous valley networks on Mars: A comparative survey. EPSC-DPS2019-1565-2. [3] Maier K.L. et al. 2011. The elusive character of discontinuous deep-water channels: New insights from Lucia Chica channel system, offshore California. [4] Skonieczny C. et al. 2015. African humid periods triggered the reactivation of a large river system in Western Sahara.</p>

Habitat fragmentation causes collapse of kelp recruitment

2020 ◽  
Vol 648 ◽  
pp. 111-123
Author(s):  
C Layton ◽  
MJ Cameron ◽  
M Tatsumi ◽  
V Shelamoff ◽  
JT Wright ◽  
...  
Keyword(s):  
Habitat Fragmentation ◽  
Patch Size ◽  
Life Stage ◽  
Extended Period ◽  
Anthropogenic Disturbances ◽  
Anthropogenic Sources ◽  
Kelp Forests ◽  
Natural Disturbances ◽  
Short Term ◽  
Turf Algae

Kelp forests in many regions are experiencing disturbance from anthropogenic sources such as ocean warming, pollution, and overgrazing. Unlike natural disturbances such as storms, anthropogenic disturbances often manifest as press perturbations that cause persistent alterations to the environment. One consequence is that some kelp forests are becoming increasingly sparse and fragmented. We manipulated patch size of the kelp Ecklonia radiata over 24 mo to simulate persistent habitat fragmentation and assessed how this influenced the demography of macro- and microscopic juvenile kelp within the patches. At the beginning of the experiment, patch formation resulted in short-term increases in E. radiata recruitment in patches <1 m2. However, recruitment collapsed in those same patches over the extended period, with no recruits observed after 15 mo. Experimental transplants of microscopic and macroscopic juvenile sporophytes into the patches failed to identify the life stage impacted by the reductions in patch size, indicating that the effects may be subtle and require extended periods to manifest, and/or that another life stage is responsible. Abiotic measurements within the patches indicated that kelp were less able to engineer the sub-canopy environment in smaller patches. In particular, reduced shading of the sub-canopy in smaller patches was associated with proliferation of sediments and turf algae, which potentially contributed to the collapse of recruitment. We demonstrate the consequences of short- and longer-term degradation of E. radiata habitats and conclude that habitat fragmentation can lead to severe disruptions to kelp demography.

The large-scale vegetation maps of the western coast of Peter the Great Bay (Far East, the Sea of Japan)

2000 ◽  
pp. 50-61 ◽  
Author(s):  
S. V. Osipov ◽  
V. P. Verkholat
Keyword(s):  
Vegetation Cover ◽  
Large Scale ◽  
Far East ◽  
Peter The Great Bay ◽  
The Sea Of Japan ◽  
Western Coast ◽  
Spatial Unit ◽  
Peter The Great ◽  
Great Bay ◽  
River Valleys

Two territories on the western coast of Peter the Great Bay were mapped in the large scale. The geobotanical mapping means revealing and displaying the essential regularities of vegetation cover. Both the spatial and temporal regularities of vegetation under natural and anthropogenic influences are well pronounced in the territory under consideration. The concept of the vegetation spatial unit (vegetation complexes) was applied as a basis for mapping. The maps and their legend were worked out as a system of vegetation combination types (vegetation combination is a spatial unit of the supracoenotic level). Such categories, as vegetation of tops and slopes, lowlands and river valleys, sea coasts reflect maximal contrasts in vegetation cover, so they are the highest level divisions of the map legend. Types of succession series and stages of series are developed for construction of the second and third levels of the legend. Communities, similar in ecotope, total species composition, saplings and some other characteristics, are referred to one type of series. 5 types of series have been distinguished: dry, fresh, moist, very moist, wet. The main factor of dynamics in considered territory is fire and the series are mainly pyrogeneous. Series are presented as sequences of vegetation stages. The vegetation stages for tops and slopes are: closed low forest — open low woodland — shrub thicket with saplings — meadow with saplings, for lowlands and river valleys they are: open low woodland — thicket of saplings — meadow or mire with saplings.

Roads of Arabia: New finds of Aqaba amphorae in the Red Sea from a newly discovered wreck site at Jeddah/Eliza shoals

2020 ◽  
Author(s):  
Rupert Brandmeier
Keyword(s):  
Saudi Arabia ◽  
Red Sea ◽  
Saudi Arabian ◽  
Maritime Archaeology ◽  
Western Coast ◽  
Research Activities ◽  
Red Sea Coast ◽  
Insight Into ◽  
Sea Coast

This paper concerns a probable shipwreck cargo of Aqaba amphorae, which was discovered during the second season of the survey project along the Saudi Arabian coast, initiated by nautical archaeologists of Philipps-University Marburg and conducted in cooperation with members of the Saudi Commission for Tourism and Heritage in autumn 2013. Seafaring and sea trade was, according to the few ancient sources and modern research activities, a hazardous endeavor in antiquity. Transport containers like the Aqaba Amphorae played a major role in sea trade, a significant number of which have been detected on various sites along the Red Sea coast and its hinterland. The chronological classification as well as the application is far from complete, and recent archaeometrical investigations help to clarify the logistical aspects of manufacturing and distribution of Aqaba amphorae. Finding a number of remains of Aqaba amphorae at a supposed shipwreck site close to Jeddah delivers new insight into the maritime routes and activities along the western coast of Saudi Arabia. The documentary material currently available is the baseline for further research in the field of maritime archaeology as it pertains to trade in the Red Sea.

MONITORING THE DYNAMICS OF THERMOABRASION COASTS AT KHARASAVEY AREA, WESTERN YAMAL (KARA SEA)

2017 ◽  
Author(s):  
Dmitry Kuznetsov ◽  
Dmitry Kuznetsov ◽  
Anatoliy Kamalov ◽  
Anatoliy Kamalov ◽  
Nataliya Belova ◽  
...  
Keyword(s):  
Human Impact ◽  
Remote Sensing Data ◽  
Kara Sea ◽  
Motor Vehicles ◽  
Yamal Peninsula ◽  
Western Coast ◽  
Frozen Ground ◽  
Coastal Dynamics ◽  
The North ◽  
Ice Content

The dynamics of thermoabrasion coasts on loose sediments under permafrost conditions are highly variable due to several factors: length of the dynamic period of the year, mechanic composition of the frozen ground and its ice content, hydrometeorological conditions, and human impact. Multiannual monitoring of the coastal zone was carried out by Lab. Geoecology of the North (Moscow State University) at the 22 km long Kharasavey deposit site, Western Coast of Yamal Peninsula (Kara Sea). The methods include direct measurements and observations (repeated topographic survey of shore transects from 1981 to 2012) along with remote sensing data analysis (images from 1964 to 2011). This allowed producing detailed characteristics of coastal dynamics. At the site, thermoabrasion coasts occupy the most part, and accumulative coasts are present in the north. Data on natural relief forming factors and ground composition are included in the detailed geomorphologic map of the site. Shore retreat rate shows correlation to amounts of wind-wave energy and to specific wind directions. Human impact on the coast includes dredging at the port channel, mining of sand, driving motor vehicles, and deposition of construction debris. Relations between shore retreat rate and aforementioned factors were studied, including dependencies on ice content, and shore segmentation was carried out. This allows for coastal dynamics forecasts in the region.

On the type locality of the steppe ribbon racer, Psammophis lineolatus (Brandt, 1838) (Serpentes: Lamprophiidae)

2020 ◽  
Vol 324 (2) ◽  
pp. 262-272
Author(s):  
I.V. Doronin ◽  
T.N. Dujsebayeva ◽  
K.M. Akhmedenov ◽  
A.G. Bakiev ◽  
K.N. Plakhov
Keyword(s):  
Caspian Sea ◽  
Type Specimen ◽  
Type Locality ◽  
Eastern Coast ◽  
Zoological Museum ◽  
Western Coast ◽  
The Caspian Sea ◽  
Original Species ◽  
Academy Of Sciences ◽  
Made In

The article specifies the type locality of the Steppe Ribbon Racer. The holotype Coluber (Taphrometopon) lineolatus Brandt, 1838 is stored in the reptile collection of the Zoological Institute of the Russian Academy of Sciences (ZISP No 2042). Literature sources provide different information about the type locality. A mistake has been made in the title of the work with the original species description: the western coast of the sea was indicated instead of the eastern one. The place of capture was indicated as “M. Caspium” (Caspian Sea) on the label and in the reptile inventory book of the Zoological Museum of the Academy of Sciences. The specimen was sent to the museum by G.S. Karelin. The “1842” indicated on the labels and in the inventory book cannot be the year of capture of the type specimen, just as the “1837” indicated by A.M. Nikolsky. In 1837, Karelin was in Saint Petersburg and in 1842 in Siberia. Most likely, 1837 is the year when the collection arrived at the Museum, and 1842 is the year when the information about the specimen was recorded in the inventory book (catalog) of the Zoological Museum of the Academy of Sciences. In our opinion, the holotype was caught in 1932. From Karelin’s travel notes of the expedition to the Caspian Sea in 1832, follows that the snake was recorded in two regions adjacent to the eastern coast of the Caspian Sea – Ungoza Mountain (“Mangyshlak Mountains”) and site of the Western Chink of Ustyurt between Zhamanairakty and Kyzyltas Mountains (inclusive) on the northeast coast of Kaydak Sor (“Misty Mountains”). In our article, Karelin’s route to the northeastern coast of the Caspian Sea in 1832 and photographs of these localities are given. The type locality of Psammophis lineolatus (Brandt, 1838) should be restricted to the Mangystau Region of the Kazakhstan: Ungoza Mountain south of Sarytash Gulf, Mangystau (Mangyshlak) Penninsula (44°26´ N, 51°12´ E).

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