Offshore Sediments

The Kizil-Dere pyrite deposit explored in detail in the 1980s in the Khnov,Borchinsky region of mountainous Dagestan, is the largest deposit of copper-zinc ores not only in the North Caucasus, but also in Europe. The relevance of the research is due, first of all to the adoption at the government level of a decision to build a copper mining and processing plant on the basis of its industrial reserves, using the latest foam flotation technologies for deep processing of polymetallic ores.

The Kizil-Dere deposit is confined to the Southern wing of the Main Caucasian (Akhtychay) fault, crossing the Khnov-Borchinsky ore district in the sub-latitudinal direction. In structural-tectonic terms, this area is part of the Shakhnabad-Mazincky anticlinorium, the core part of which is composed of rocks of the Lower-Middle- Jurassic flyschoid sequence. The main pyrite deposits are Pravoberezhnaya(Right river embarkment) and Levoberezhnaya (Left river embarkment), localized in terrigenous deposits of the Upper Aalenian, with a thickness of more than 1100 m.
Tin-Cobalt-Arsenide Mineralization in pyrites ore deposits Kizil-Dere (Mountanous Dagestan) in pyrite ore Kizil-Dere locality, Cobalt is a typomorphic impurity with 100% frequency of occurrence in exploration samples, which determines the need for it mineralogical and technological assessment as a potenally industrial critical semi-component.

Laboratory and technological testing of 5 representative samples of pyrites ores from the Kizil-Dere deposit was carried out by employees of the Southern Federal University and the Central Chemical Laboratory “Sevkavgeologia” (Essentuki) using the VIMS method on small-sized enrichment flotation machines FM-2m. In the experiments, the traditional scheme of foam-flotation separation of ore and non-metallic minerals was used, including the sequential execution of the following technological operations:
1 – Addition or initial sample to 0.5 mm; 2 – excision of sample in a shear mill up 2 00 mesh (50 grams of ore + 100 ml of water) – 28 min; 3 – Pulp aeration at 4000 rpm.- 15 minutes; 4 – adding <<foaming agent>> (butyl xanthate – 3 ml) and <<collector>> (terpinol T-66 – 1 ml); 5 – agitation – 2 minutes; 6 – direct flotation at 4000 rpm.
The concentrations of Cu, As, Sn, Co, and Ni were determined in the resulting enrichments products by emission spectral analysis.

In soft-bottom marine ecosystems, bedform variation is induced by wind-and tidal-driven hydrodynamics. The resulting megaripples, sand waves and sandbanks form a spatially and temporally heterogeneous seafloor landscape. The strong physical forces imposed by the migration of these bedforms are important determinants for the occurrence of different macrozoobenthic species. Quantifying the effect of these forces can help in differentiating natural-and anthropogenically induced physical stressors. However, large-scale mapping of seabed morphology at high resolution using multibeam echosounder is challenging, costly and time-consuming, especially in shallow seas, prohibiting wide swaths. Instead, their bathymetry is typically studied using single-beam transects that are interpolated to bathymetric grids with a relatively coarse resolution (20 m). However, this leaves out information on smaller scale (<20 m) bedforms that can be ecologically relevant. In the Dutch Wadden sea, a shallow tidal system, we characterized bedform variation at high resolution using single-beam data for the first time. We calculated a 2-D Terrain Ruggedness Index (TRI) at sub-meter resolution along the single-beam transects and interpolated the results to a full 3-D grid. We then validated the result by relating TRI to independently modeled hydrodynamic parameters and to the distribution of macrozoobenthic species. We found that TRI successfully integrates the variation of tidal-driven bed shear stress and wave-driven orbital velocity. In addition, we found TRI to be a good predictor of the occurrence of macrozoobenthic species. The inferred small-scale bedforms provide valuable information for separating the relative importance of natural dynamics versus anthropogenic disturbances such as dredging and bottom trawling activities. We discuss that by repurposing already available single-beam data in this way, bedforms can be characterized at high resolution without the need for additional equipment or mapping campaigns, yielding novel input to decision-making on marine management and conservation.

Beach is one of the most conspicuous geomorphic features of a coastal region. Interpretation of any beach environment warrants detailed analysis of its morphological features, prevailing hydrodynamic conditions, actions of wind and cyclonic surges which bring discernible changes in the coastal configurations. Various beach features have been dealt here in details.

This study presents the small scale bedform states found off the South-Holland coast during a 31+ days field observation of seabed acoustic imagery and near the bed velocities. Six main bed states were encountered: current ripples (C), wave ripples (W), combined wave-current ripples (WC), current ripples with subordinate wave ripples (Cw), wave ripples with subordinate current ripples (Wc) and poorly developed ripples (P). Direct visual detection of the bed state from the images showed good agreement with a simple predictor based on the mobility number. The most frequent type of bedform was C which is governed by the tidal currents. Wave ripple prevailed only during a storm with waves higher than 2 m. The combined Cw, WC and Wc types comprised 22% of the occurrences. Poorly developed ripples were associated with the neap tide during fair weather conditions.

More than half of Catbalogan barangays (villages) are situated along the Maqueda Bay, the primary source of food for Samariños (people of Samar). Sixty percent of these coastal barangays have no direct access to waste disposal facilities such as garbage trucks and landfill. Almost 50% of domestic waste from these barangays is thrown directly to the sea, while 22% partly dispose their waste into Maqueda bay or a total of 7201 kg of waste daily. An improvised 3-dimensional micro-model shows how wastes are transported from one barangay to the other. The waste transport goes beyond barangay boundaries for many of waste travel to the coast of other municipalities and probably to other provinces. Approximately about 33% of fresh wastes float and are transported to other places, most of the remaining waste rot onsite making the site dark, dirty and has foul smell. Waste disposal practices of coastal towns/cities affects each other, therefore proper waste disposal practices must be widely practiced.

The green mussel (Perna viridis) is an excellent source of protein, fat and carbohydrates and a popular source of food for local communities throughout Southeast Asia, including Indonesia. Because the mussel reproduces throughout the year, requires no supplemental food input, grows to harvestable size in about six months and requires no mangrove removal for pond construction, it is particularly promising as a sustainable aquaculture product for culture in erosion-sensitive mangrove coasts. Additionally, mussel culture does not require highly sophisticated techniques, knowledge or equipment, which makes it particularly suitable for use in small-scale artisanal settings. Indonesia lags far behind in the culture of molluscs and little recent work has been done on mussel culture in Indonesia. Green mussel culture in the country takes place in sheltered marine mangrove waters and traditionally only involves the use of bamboo stakes. In the Demak Regency, northeast of Semarang on the northern coast of central Java, negative impacts from shrimp farming have promoted interest in mangrove-friendly alternatives. This article-adapted and summarized from the original publication (https://doi.org/10.1111/are.14900) [Rejeki, S. et al. 2020. Increased production of green mussels (Perna viridis) using longline culture and an economic comparison with stake culture on the north coast of Java, Indonesia. Aquaculture Research, 2020; 00:1-8.]-reports on feasibility trials to develop green mussel culture as an alternative livelihood for the impoverished coastal shing communities of Demak, Java. The green mussel is already being harvested from man-made structures in the surrounding areas and, as is the case with several other bivalves, is a well-established local food. Study setup The study was carried out in Morosari Village, on the northern coast of Central Java, Indonesia, just 2 km northeast of Semarang in the coastal zone of the Demak Regency. The area was selected based on its physical suitability for aquaculture and the absence of potential interference from other shing activities.

Cocos Bay on the east coast of Trinidad comprises a barrier beach system that protects the Ramsar listed freshwater Nariva Swamp from the high energy environment of the Atlantic. The Manzanilla beach with its open bay morphology, and exposure to the Atlantic Ocean presents an interesting dynamic. There have been many developments in coastal geomorphology in terms of studying beach and nearshore changes. However, most studies on beach classification overlooked the dynamics of beaches in the Caribbean exposed to the Atlantic Ocean. Attempts to classify Manzanilla beach into the existing frameworks for beach state classification has proven to be problematic. This paper evaluates the applicability of such beach state classifications on beaches exposed to the Atlantic. Results indicate that an adjustment of the original limits for the dissipative beach domain is necessary in order to classify this beach. A Manzanilla dissipative domain is also proposed as a modification of the previous l...

In contrast to the increasing aquaculture production of mussels worldwide, production in the European Union (EU) has shown a decreasing trend over the last two decades. Aquaculture production of mussels in the EU peaked in the late 1990s at more than 600 000 tonnes; by 2016, production volume had dropped by 20% to 480 000 tonnes. As mussel production represents more than ⅓ of EU aquaculture production, this decrease is an important contributor to the stagnation of EU aquaculture. Previous studies have suggested diseases, lack of mussel seed (spat), and low profitability as the main causes of the EU mussel production decrease. In this study, we investigate how economic and environmental factors have contributed. Moreover, we examine if the different mussel production techniques (raft, longline, on-bottom, and 'bouchot') have been differently affected, by analysing the economic performance and cost structure evolution for the period 2010-2016. We complement these results with a SWOT (strengths, weaknesses, opportunities, and threats) analysis of the EU mussel sector based on expert knowledge.

Conventional forced models of bedform dimensions link bedform wavelength and height to wave orbital excursion and wave orbital velocity. Self-organization models, however, suggest that bedform wavelengths either grow, remain stable, or are wiped flat, but are unable to reduce in length. This paper presents measurements of megaripple evolution on a macrotidal sandy dissipative beach at Perranporth, England, using measurements from a Sand Ripple Profiler. Measurements were made as the tide flooded and ebbed over the instruments, giving a cross-section of the moving surf zone for 12 separate tides. Water depths varied from 1 to 6 m, and wave heights were up to 2.2 m. The data allowed megaripple dimensions to be observed with heights up to 30 cm and wavelengths up to 1.8 m. Megaripples were observed to grow and decay in both length and height. Megaripple spacing did not increase consistently with age of ripple. Megaripple lengths changed at rates of up to 5 cm/minute, and height changed at rates of up to 0.5 cm/minute. Maximum changes took place in large orbital velocity conditions. At orbital velocities > 0.5 m/s, ripples attempted to stabilize at a wavelength related to the orbital excursion, suggesting a forced mode. The most stable ripples had the greatest height and steepness. At orbital velocities < 0.5 m/s the spacing was greater than the orbital excursion, suggesting self-organized growth may be a more appropriate model for small orbital velocities.

Conventional force models of bedform dimensions link bedform wavelength and height to wave orbital excursion and wave orbital velocity. Self-organization models, however, suggest that bedform wavelengths either: grow, remain stable, or are wiped flat, but are unable to reduce in length. This paper presents measurements of megaripple evolution on a macrotidal sandy dissipative beach at Perranporth, England, using measurements from a Sand Ripple Profiler. Measurements were made as the tide flooded and ebbed over the instruments, producing a cross-section of the moving surf zone for 12 separate tides. Water depths varied from 1 to 6 m, and wave heights were up to 2.2 m. The data allowed megaripple dimensions to be observed with heights up to 30 cm and wavelengths up to 1.8 m. Megaripples were observed to grow and decay in both length and height. Megaripple spacing did not increase consistently with age of ripple. Megaripple lengths changed at rates of up to 5 cm/minute, and height changed at rates of up to 0.5 cm/minute. Maximum changes took place in large orbital velocity conditions. At orbital velocities > 0.5 m/s, ripples attempted to stabilize at a wavelength related to the orbital excursion, suggesting a forced mode. The most stable ripples had the greatest height and steepness. At orbital velocities < 0.5 m/s the spacing was greater than the orbital excursion, suggesting self-organized growth may be a more appropriate model for small orbital velocities.

A Sand Ripple Profiler (SRP) was deployed in a rip channel on a dissipative sandy beach to measure bedform height (∆), length (λ) and migration rate (Mr¬) throughout a macro-tidal cycle with an offshore significant wave height of 0.7 m and peak period of 10 s. At lower tidal elevations in the strong offshore flow of the rip current (maximum = 0.4 m/s) bedforms (∆ = 0.15 m, λ = 3 m) were found to migrate offshore (Mr = 0.21 m/hr). Outside of active rip current conditions (water depth (h) = &gt;~2.5 m) bedforms were found to be of smaller scale (∆ = 0.09 – 0.12 m, λ = 1 – 1.2 m) migrating onshore at a rate of 0.35 m/hr at mid tide (h = 3.3 m) and 0.03 m/hr at high tide (h = 6.3 m). Onshore migration rates were found to increase with increased wave skewness and velocity variance.

Field measurements of wave ripples and megaripples were made with a Sand Ripple Profiler in the surf and shoaling zones of a sandy macrotidal dissipative beach at Perranporth, UK in depths 1-6 m, and significant wave heights up to 2.2 m. A frequency domain partitioning approach allowed quantification of height (η), length (λ) and migration rate of ripples and megaripples. Wave ripples with heights up to 2 cm and wavelengths ~20 cm developed in low orbital velocity conditions (u m < 0.65 m/s) with mobility number ψ < 25. Wave ripple heights decreased with increasing orbital velocity and were flattened when mean currents were > 0.1 m/s. Wave ripples were superimposed on top of megaripples (η = 10 cm, λ = 1 m) and contributed up to 35% of the total bed roughness. Large megaripples with heights up to 30 cm and lengths 1-1.8 m developed when the orbital velocity was 0.5-0.8 m/s, corresponding to mobility numbers 25-50. Megaripple heights and wavelengths increased with orbital velocity, but reduced when mean current strengths were > 0.15 m/s. Wave ripple and megaripple migration was generally onshore-directed in the shoaling and surf zones. Onshore ripple migration rates increased with onshore-directed (+ve) incident wave skewness. The onshore migration rate reduced as offshore-directed mean flows (undertow) increased in strength, and reached zero when the offshore-directed mean flow was > 0.15 m/s. The migration pattern was therefore linked to crossshore position relative to the surf zone, controlled by competition between onshore-directed velocity skewness and offshore-directed mean flow.

Sediment samples under the Longline and Stake Method of mussel culture were analyzed to determine their % Organic Matter and % Carbon contents which can help in prevention of enhanced sedimentation and water fouling. Using the chromic acid method for the soil analysis, the % OM and % C under the Longline method was recorded having higher measures of organic matter and carbon content. Results showed that the possible cause of increased organic matter and carbon content is by the location of the culture methods being in close proximity from the bay area, where runoff from heavy rains wash away Organic matter and Carbon from the land and into the bay. Moreover, the study concludes that not only the mussels cause the reduction of soil quality but anthropogenic activity accelerates sedimentation and increase of nutrient levels that could cause eutrophication.

Keywords: sedimentation, longline method, mussel culture, organic matter, carbon

This study presents the small scale bedform states found off the South-Holland coast during a 31+ days field observation of seabed acoustic imagery and near the bed velocities. Six main bed states were encountered: current ripples (C), wave ripples (W), combined wave-current ripples (WC), current ripples with subordinate wave ripples (Cw), wave ripples with subordinate current ripples (Wc) and poorly developed ripples (P). Direct visual detection of the bed state from the images showed good agreement with a simple predictor based on the mobility number. The most frequent type of bedform was C which is governed by the tidal currents. Wave ripple prevailed only during a storm with waves higher than 2 m. The combined Cw, WC and Wc types comprised 22% of the occurrences. Poorly developed ripples were associated with the neap tide during fair weather conditions.

Sediments are solid, fragmented particulate matter (silt, sand, and gravel), which are transported and deposited by physical processes such as water, wind, and ice. Sediments consist of loose, solid particles originating from the weathering and erosion of rocks, or chemical precipitation from solution, including secretion by organisms in water.

Cocos Bay, Trinidad has a very dynamic system owing to the open bay morphology, and being exposed to the Atlantic Ocean. It is apparent that the interplay of coastal processes, sediment characteristics, and coastline orientation account for the variations in the intensity of the processes operating at each beach. While the nearshore coastal geomorphology has received much attention by researchers, the offshore bathymetry and sedimentology remained fairly unresolved.  In order to fully appreciate the nearshore-offshore relations at this bay, it became necessary to conduct hydrographic surveys. This paper examines the offshore bathymetry and sediment characteristics at several of the sections in Cocos Bay. Results indicate that megaripples and sandwaves with superimposed ripples dominate the offshore region; where the mega-ripples have a relationship with the surface wavelengths of oncoming incident waves.

The process of erosion and accretion taking place along a stretch of coastline is governed by the geology of the area and the direction and strength of the wave attack. The Manzanilla beach is a very dynamic system owing to the open bay morphology, and being exposed to the Atlantic Ocean. The Las Cuevas beach is less dynamic, due to its embayed characteristic, and being open to the Caribbean Sea, a much smaller body of water. It is apparent that the interplay of coastal processes, sediment characteristics, and coastline orientation account for the variations in the intensity of the processes operating at each beach. The study seeks to explore the similarities and differences in processes at work in shaping these coastlines. This paper presents the data collected on coastal processes, sediment and morphological characteristics of both beaches.

"The shoreline monitoring component of the Coastal Conservation Project which commenced in 1988 provides valuable insights on the dynamics of the coastline. The scientific data are used by government and other agencies in formulating policies and plans for the coastline. While coastlines of Trinidad and Tobago are monitored under this project, this report presents only the research conducted in Trinidad during the period 2004 – 2008.  The report focuses on the 25 beaches and bays monitored, comprising 64 beach profiling stations. The report reveals that most of the beaches and bays in Trinidad are in a state of dynamic equilibrium where the seasonal changes of erosion and accretion occurring on the beaches revolve around a state of stability.
The beaches on the north coast are less prone to erosion due to the more resilient metamorphic rocks that form these bays. However, changes in sand elevations due to normal wave processes do occur. During the period 2004–2008 all beaches monitored on the north coast experienced a state of dynamic equilibrium with the exception of the east and west stations at Las Cuevas Bays and the western part of Blanchisseuse Bay.
All east coast beaches also experienced dynamic equilibrium except the southern part of Cocos Bay. Erosion in this part of the coastline threatened to breach the roadway and prompted government to construct a 2 km long rip rap revetment as a means of shoreline protection. This has curbed the erosion in the protected area but to the extreme south erosion is ongoing at a rate of 2.5 m/yr since 2005.
The beaches on the south coast experienced dynamic equilibrium except at the western section of Guayaguayare Bay.  Erosion in this part of the bay averaged 1.20 m/yr since 2004. This erosion can be attributed to both offshore and onshore open trenching for pipe laying activities.
The west coast beaches are located within the Gulf of Paria which provides a sheltered environment.  Erosion however was observed at North Chatham which averaged 1.20 m/yr since 2004.  Erosion was also observed at the western section of Guapo Beach in Clifton Hill during 2006 and 2007. On the south-western peninsula, while Punta del Arenal (Icacos) is experiencing accretion, Columbus Bay is being eroded. The erosion has prompted property owners to employ the use of coastal protection measures such as revetments and groins. This report makes recommendations for modifying the current monitoring regime as well as highlights further research needs.
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