Heavy metals in the Bay of Cadiz, Spain have increased in the twentieth century.
In this paper the time evolution of heavy metal concentration of Pb, Zn, Cd and Hg, in the sediments of the Bay of ...Cádiz (southwest of Spain) is studied during the past century, as a result of the industrial influence in the zone. The study has been performed using sedimentary profiles that have been extracted from the seabed. The measurement of
210Pb and
137Cs radionuclides has provided the dating of the sediment layers, up to a depth corresponding to the age of 115 years. The relative sedimentation rates obtained are around 0.2 cm/year. The
137Cs activity profile reflects the concentration of this radionuclide in the atmosphere and into aquatic systems during the second half of the twentieth century. This profile has been used to ratify the results provided by the
210Pb dating method.
A shallow (depth < 20 m) layer of water, fresh, brackish or saline, covers millions of square kilometres of sediments and bedrock along the world's coastlines, rivers, lakes, and lagoons. These ...geological units are extremely important, both environmentally and economically. Airborne electromagnetic (AEM) has been used with some success to obtain the bathymetry of shallow surface water ((Macnae et al., 2004; Vrbancich et ah, 2000; Vrbancich et ah, 2005). Some attempts have also been made to retrieve information about the sediments under the water bottom (Vrbancich et ah, 2000). The limited research that has been carried out so far tells us that we need to make improvements and further developments, both in hardware, as well as in data processing and modelling. This manuscript aims at making a contribution at the data inversion level, by applying constrained inversion methodology to different AEM datasets flown over water. In constrained inversion, adjacent model parameters are regularized through lateral constraints that allow information to flow from soundings that contain more information to those that contain less. We present results from constrained inversion (smooth and few layers) of a portion of SkyTEM survey (a helicopter borne time domain AEM system) flown in Denmark, and of a RESOLVE survey (a helicopter borne frequency domain AEM system) carried out along the Murray River in Australia. In both cases bird height was included as an inversion parameter, allowing the inversion to compensate for errors in laser altimeter readings over water.
Sidescan sonar images, high-resolution seismic profiles, sediment samples and seabed photographs have been used to characterize the seabed sedimentary environment of the continental slope west the ...Shetland. The seabed morphology and sedimentary regime in this area result primarily from sediment deposition during the last glacial, modified by erosion and re-distribution of surficial sediments during the Holocene. Examples of glacial age features which have a significant effect on present day seafloor morphology include iceberg ploughmarks, glacigenic debris flows and channels cut into glacigenic sediment sequences. Holocene modification of the late glacial seafloor by bottom currents has given rise to large areas of gravel lag deposits and sand bedforms at scales ranging from tens of centimetres to kilometres. However, evidence for strong currents, directed towards the NE, is largely restricted to the upper slope. Much of the gravel covered seafloor on the lower slope shows little evidence for strong currents, suggesting that low sediment input during the Holocene is the main reason why gravel of glacial age remains at the seabed. A localised contourite sand deposit on the lower slope suggests peak current speeds of a few tens of cm
s
−1, with derivation of the sand from a relict sandwave field which occurs immediately up current and upslope from the contourite body.
The continental margin off Lofoten, Vesterålen, and Troms comprises a great variation of marine landscapes, ranging from 0 to 3,000 m in depth largely influenced by previous glaciations and ...oceanographic processes governed by three different water masses. The biological communities identified with multivariate analyses of results from visual surveys were strongly correlated with water mass distribution, sediment type, and various topographic indices. Broadscale geomorphic features such as canyons and troughs have a significant influence on the distribution of sediment types and biological communities through their modification of current patterns. Currents also influence the distribution of geomorphic features such as sand waves and coral reefs. At a broadscale, the largest faunistic change occurs between the warm Atlantic water and the cold intermediate water mass at depths around 700 m. Banks and plains are important geomorphic elements on the continental shelf off LVT. The biological communities identified with multivariate analyses of results from visual surveys were strongly correlated with water mass distribution, sediment type, and various topographic indices. Broadscale geomorphic features such as canyons and troughs have a significant influence on the distribution of sediment types and biological communities through their modification of current patterns. Currents also influence the distribution of geomorphic features such as sand waves and coral reefs. At a broadscale, the largest faunistic change occurs between the warm Atlantic water and the cold intermediate water mass at depths around 700 m.
The Kvarken Archipelago is located in the European epicontinental basin, the Baltic Sea. The Baltic Sea is one of the largest brackish water bodies in the world. The Kvarken area, between Finland and ...Sweden, is the narrowest part of the Gulf of Bothnia. It forms a submarine sill (25 m) that separates the Bothnian Sea in the south from the Bothnian Bay in the north. The majority of the Kvarken Archipelago is very shallow (0–25 m) and shoaly, with ∼7,000 islands and islets. Glacioisotatic land uplift rate is ∼8.0–8.5 mm/year. The boulder-rich De Geer moraines are the most characteristic geomorphic features within the area, creating a unique, washboard-like submarine landscape. Because the area is a transition zone of salinity levels at critical levels to both marine and limnic species, the diversity of marine life is poor. The local bladder wrack, Fucus radicans, is characteristic of hard bottoms in the shallow areas with salinity up to 4.5‰. The region has undergone several glaciations during the past approximately 3 million years, which has resulted in periods of repeated glacial erosion and sediment accumulation. During the latest glaciation, the Kvarken Archipelago was located close to the center of the Weichselian ice sheet, which reached a thickness of approximately 3 km during the glacial maximum. The seafloor morphology of the Kvarken area is characterized by broad-scale geomorphic features including mounds, plains, basins, and some sea valleys (holes). However, the seafloor bathymetry follows mainly the surface of the bedrock, and the relief of the area is relatively low.
Elementary studies on surface sediment physical properties (physical-mechanic property, engineering features, acoustic parameters) of the Nansha Islands sea area in the South China Sea reveal that ...the seabed sedimentary environments are important factors of controlling sediment physical properties and the relations between them affect one another. At the same time, the relative figures of sediment physical properties and some experienced relationsare given, which are beneficial to the later research and further studies.
Даний опис затоплених морем стародавніх частин річок Чорна і Бельбек, виявлених на дні зовнішньої акваторії Севастополя. Раніше обидві річки мали єдине гирло, на глибині 90 – 96 м сучасного ...чорноморського шельфу знайдено місце злиття їх палеорусел. Реліктовий, нині поглинений морем фрагмент р. Чорна відрізняється складною конфігурацією. У місцях, де дно складене з твердих осадових порід контур русла повторює форму складок місцевості, тоді як на ділянках з рихлими ґрунтами деталі палеорічки розмиті або простежуються фрагментарно. Ширина русла складає 420 – 490 м глибина може досягати 11 м. Палеорусло р. Бельбек характеризується набагато меншою звивистістю, чим р. Чорна і його заглиблення не перевищує 6 м. Донні відкладення палеорічки Чорна мають негативні значення редокспотенціалу і підвищений вміст органічних речовин. Виявлені реліктові об'єкти можуть мати важливе значення для вивчення екології сучасних бентосних угруповань.
The description is presented for the first researches of ancient parts of the Chernaya and Belbek rivers flooded by sea, which were detected at the sea floor of the Sevastopol coastal area. Earlier both rivers had a joint estuary; locality of confluence of their paleo-riverbeds was found at a depth 90 - 96 m of the present-day Black Sea shelf. Relic fragment of the Chernaya River, nowadays covered by sea, differs by thecomplicated configuration. In the limited provinces where seabed was done by hard primary rocks its contours retrace the form of sea floor, while at the areas with friable sediments the most details of the river structure are degraded or can be tracked fragmentary. The width of a river channel comes to 420 - 490 m, depth can reach up to 11 m. Paleo-rivarbed of Belbek is characterized by much smaller sinuosity than Chernaya River and deepening of channeldoes not exceed 6 m. Bottom sediments of the Chernaya paleo-river have negative levels of redox potential as well as increased content of organic matter. Discovered ancient objects can be important for study of ecology of the modern benthos communities.
Дано описание затопленных морем древних участков рек Чёрная и Бельбек, обнаруженных на дне внешней акватории Севастополя. Ранее обе реки имели единое устье; на глубине 90 – 96 м современного черноморского шельфа найдено место слияния их палеорусел. Реликтовый, ныне поглощённый морем фрагмент р. Чёрная отличается сложной конфигурацией. В местах, где дно сложено из твёрдых осадочных пород очертания русла повторяют форму складок местности, тогда как на участках с рыхлыми грунтами детали строенияпалеореки размыты или прослеживаются фрагментарно. Ширина русла 420 – 490 м, глубина может достигать 11 м. Палеорусло р. Бельбек характеризуется гораздо меньшей извилистостью, чем р. Чёрная, и его заглуб-ление не превышает 6 м. Донные отложения палеореки Чёрная имеют отрицательные значения окислительно-восстановительного потенциала и повышенное содержание органических веществ. Обнаруженные реликтовые объекты могут иметь важное значение для изучения экологии современных бентосных сообществ.
