Changes in detrital sediment supply to the central Yellow Sea since the last deglaciation

The sediment supply to the central Yellow Sea since the last deglaciation was uncovered through clay mineralogy and geochemical analysis of core 11YS-PCL14 in the Central Yellow Sea Mud (CYSM). The core can be divided into four units based on the various proxies, such as grain size, clay mineralogy, geochemistry, and Sr and Nd isotopes: Unit 4 (700–520 cm; 15.5–14.8 ka), Unit 3 (520–310 cm; 14.8–12.8 ka), Unit 2 (310–130 cm; 12.8–8.8 ka), and Unit 1 (130–0 cm; <8.8 ka). Unit 2 is subdivided into two subunits, Unit 2-2 (310–210 cm; 12.8–10.5 ka) and Unit 2-1 (210–130 cm; 10.5–8.8 ka), according to smectite content. Comparison of the clay mineral compositions, rare earth elements, and εNd indicate distinct provenance shifts in core 11YS-PCL14. Moreover, the integration of clay mineralogical and geochemical indices show different origins according to particle size. During the late last deglaciation (Units 3 and 4, 15.5–12.8 ka), Unit 4 sediments originated from all potential provenance rivers, such as the Huanghe, Changjiang, and western Korean rivers, while the source of coarse sediments changed to the Huanghe beginning with Unit 3. Fine-grained sediment was still supplied from all rivers during the deposition of Unit 3. Early Holocene (Unit 2) sediments were characterized by oscillating grain size, clay minerals, and moderate εNd values. In this period, the dominant fine-sediment provenance changed from the Huanghe to the Changjiang, whereas coarse sediments most likely originated from western Korean rivers. The Unit 1 CYSM sediments were sourced primarily from the Changjiang, along with minor contributions from the western Korean rivers. Possible transport mechanisms concerning such changes in the sediment provenance include paleo-river pathways, tidal stress evolution, and the development of the Yellow Sea Warm Current and coastal circulation systems, depending on the sea level fluctuations.

Coarse sediment tracing experiment at the Promenade des Anglais (Nice, France)

&lt;p&gt;&lt;span&gt;Coarse sediment nourishments are increasingly used as a form of coastal protection at sites where the natural shore is affected by erosion processes. Based on the extent of the erosion effects, they can be just an integration to the backshore or rather an artificial reconstruction of a beach that has been completely eroded. In both cases, the comprehension of the physical processes affecting coarse sediments would be crucial to define the transport patterns, which are not completely understood yet. In this sense, short-term tracing experiments have already proved to be a reliable method to gain a significant amount of data about sediment transport in brief timespans. The aim of this work is quantifying the transport rate of coarse tracers 4, 24 and 48 hours after the injection during a time interval characterized by very low to no wave activity. Pebbles of about 7 cm in mean diameter were sampled on the coarse-clastic beach of the Promenade des Anglais in Nice (France), which needs yearly nourishments because of a reported huge sediment loss to the offshore. Since 1969, around 600 000 m3 have been brought in order to maintain the coastline. Once the pebbles fall downslope, no natural process is able to move them back landward due to the steepness of the shoreface. Passive RFID cylinder glass tags have been inserted into the tracers, which have been measured with a caliper and weighed. A 110 m long portion of the public beach has been selected as the site of the experiment because it is confined within two consecutive boulder groynes, which reduce longshore sediment exchange with the adjacent sectors. The pebbles have been injected along 21 transects, two at the berm crest, two in the swash zone and two at the step crest. The tracers have been inserted in the surface of the beach to avoid immediate displacement due to the uprush and backwash flows. The surrounding size of the sediments was on average slightly finer than the tracers. Visual observations right after the injection allowed us to report a strong downslope movement of the swash zone pebbles. The first detection campaign after 4 hours reached just about 60% of recovery rate, which is surprisingly low compared to previous such experiments at different locations. Topographic surveys made contextually revealed the destruction of the fair-weather berm during the rising tide, which led to the burial of a large number of tracers. During the night, low-energy waves managed to wipe out the thin layer of gravel, unearthing back several marked pebbles that had not been detected before: the recovery rate was beyond 90% after 24 hours. This dataset confirms the high transport rate of coarse sediments in very short timespans and under very low energy state: such condition is responsible of moving downslope the tracers with little chance of getting them back up unless the wave motion increases significantly. Such high mobility might also imply a high wear of coarse sediments, which in turn can contribute to volume loss of the beach.&lt;/span&gt;&lt;/p&gt;

Seabed Characterization through Image Processing of Side Scan Sonar Case Study: Bontang and Batam

Acoustic waves propagate through a medium meet the Snell’s Law, its energy is reflected and some are scattered back at certain angle. The Side Scan Sonar (SSS) methods use this principle to identify seabed character. The intensity of the backscatter greatly depends on the morphology and sediments texture or rocks distributed on seabed.The intensity of backscatter waves is a representation of the morphology, sediments texture, and types of rock that distributed on the seabed, therefore it is possible to estimate sedimentary texture and identify the presence of rocks or coral reefs based on this information. In this publication authors estimate sediments texture, rocks or coral reefs based on backscatter intensity through the image processing on the Side Scan Sonar (SSS) image. Intensity will be converted into pixel values on the image with range value 1-255 (gray scale image) and entropy values which are statistical measures of randomness. Entropy value is maximum when most of pixel value image is in the middle of the colour spectrum range (between very dark to very bright), in contrast, it is minimum when pixel value is in the spectrum of very dark or very bright. Based on both parameters, classification is conducted. The classification is carried out on the SSS image at Bontang and Batam that have very different seabed characters.The classification results using an image processing shows that the distribution of sediment textures consist of 4 (four) classes for either Batam or Bontang. In the Bontang area, very fine sediments were identified which are associated with low value of both intensity and entropy - dark zones in gray scale images, and coarse sediments associated with high value of both intensity and entropy - bright zone in the gray scale image. Similar characteristic is observed in Batam area, which are identified fine sediment (associated to low intensity) - coarse sediments (high intensity). In contrast to Bontang, in Batam the entropy exhibit the opposite value, high value are correlated to fine sediment and vice versa. This might be due to the presence of rocks and sedimentary structures.Keywords: Side Scan Sonar, Intensity, Backscatter and entropy.Gelombang akustik sebagian besar energinya dipantulkan memenuhi prinsip snellius dan sebagian kecil dihamburkan balik dengan sudut. Metode Side Scan Sonar (SSS) memanfaatkan prinsip hambur-balik gelombang untuk mengidentifikasi permukaan dasar laut. Intensitas gelombang dari karakter hambur-balik akan sangat tergantung morfologi dan tekstur sedimen atau batuan dari permukaan dasar lautnya. Intensitas gelombang hambur-balik merupakan representasi dari morfologi, tekstur sedimen, dan jenis batuan yang tersebar di permukaan dasar laut, sehingga sangat memungkinkan untuk melakukan estimasi tekstur sedimen dan identifikasi keberadaan batuan maupun terumbu karang berdasarkan informasi tersebut. Pada publikasi ini akan dilakukan estimasi tekstur sedimen atau batuan berdasarkan intensitas hambur-balik melalui image yang dihasilkan oleh Metode Side Scan Sonar (SSS). Intensitas akan dikonversi ke dalam nilai pixel dalam image dengan rentang nilai 1-255 (gray scale image) dan nilai entropi yang merupakan ukuran statistik ketidakteraturan dari image. Entropi akan maksimum ketika nilai pixel kebanyakan di tengah dari rentang spektrum warna dan sebaliknya akan minimum ketika nilai pixelnya berada di spektrum warna sangat gelap atau sangat terang. Berdasarkan kedua parameter tersebut, kemudian dilakukan klasifikasi. Klasifikasi dilakukan pada data SSS Bontang dan Batam yang memiliki karakter permukaan dasar laut yang sangat berbeda.Hasil klasifikasi dengan image processing memperlihatkan pola sebaran tekstur sedimen masing-masing terdiri dari 4 (empat) kelas baik untuk Batam atau Bontang. Pada area Bontang teridentifikasi sedimen sangat halus yang berasosiasi dengan intensitas dan entropy rendah - zona gelap pada gray scale image dan sedimen kasar yang berasosiasi dengan intensitas dan entropy tinggi - zona terang pada gray scale image. Karakter yang sama juga teramati pada area Batam, yaitu teridentifikasi sedimen halus (berasosiasi dengan intensitas rendah) - sedimen kasar (intensitas tinggi). Namun, berbeda dengan di Bontang, di Batam nilai entropi menunjukkan nilai yang sebaliknya, yaitu nilai tinggi berkorelasi dengan sedimen halus, dan sebaliknya. Hal ini diperkirakan akibat keberadaan batuan dan struktur sedimen.Kata Kunci: Side Scan Sonar, Intensitas, Hambur balik dan Entropi.

Revisited Syllidae of the English Channel coarse sediment communities

Among the polychaetes, the Syllidae comprise numerous species whose study over many years has benefitted from valuable revisions and descriptions of new species in Europe. This abundant literature proves very useful for revisiting the taxonomy and distribution of the Syllidae in the English Channel (EC), mainly as regards existing studies on coarse sediment communities in the eastern part of the Channel. This habitat is one of the most widespread in the EC and is known as favourable for the small polychaete fauna including Syllidae. A 2-year survey (winter and summer sampling periods) covering 19 stations, associated with theBranchiostoma lanceolatumcoarse sand community offshore Dieppe-Le Tréport, led to the identification of 6537 individuals from 29 taxa including 27 species. Six fine sand stations were also sampled in which only 12 individuals were collected. Among these species, seven are new for the EC polychaete fauna and six others are observed for the first time in the eastern part of the EC. All the new species for the EC are warm temperate species previously only known south of the Bay of Biscay. The Syllidae list given in Dauvinet al. (2003) has been re-analysed and amended with our list and that of the Chausey Archipelago study (Olivieret al., 2012). To date, 91 Syllidae species have been recorded in the EC and are established mostly in coarse sediments.

Mapping the penetration and retention potential of two weathered diluted bitumen crude oils for the shorelines of Northern British Columbia, Canada

With the increase in bitumen production from Alberta's oil sands, there is a related increase in the transport of non-conventional crude oil throughout Canada including proposed pipeline projects to move diluted bitumen (dilbit) to facilities on the East and West coast of Canada. While the behaviour of conventional oil is well known, little information is available about the fate of any potential dilbit spills on marine shorelines. As a part of Enhancing Marine Safety Strategy launched in 2013 by the Government of Canada, a R&D program has been developed by the Emergencies Sciences and Technology Section (ESTS) from Environment and Climate Change Canada (ECCC) to study the behaviour of non-conventional oil. More precisely, one of the objectives is to develop tools to help oil spill responders to predict the fate of dilbit on shorelines of Northern British Columbia (BC). To address this objective, we collected data from three sources; BC segmentation of the upper intertidal zone for the Douglas Channel and Haida Gwaii Island, particle size analysis results of sediment samples collected directly from Northern BC shoreline and meso-scale laboratory research results on the penetration and retention of dilbit in different type of sediment. This last experiment was conducted in laboratory by the contractor Coastal and Ocean Resources Inc. to estimate penetration (cm) and retention (% of the loading) of different weather dilbit (AWB [18% loss by weights] and CLB [15% loss by weight]) in different types of sediments (from coarse sand to very large pebble). These previous data were combined to associate each shoreline type with dilbit penetration and retention data. For each shoreline type, we did a quantitative (penetration) and qualitative (retention) estimation of dilbit properties. The estimations were also visually represented on ArcMap 9.1. In Northern British Columbia, most of the shoreline is associated with low penetration and low retention corresponding to bedrock substrate. Conversely, high penetration and retention is mainly associated with coarse sediments like pebble/cobble beaches. These shoreline types represent an indicator of difficulty of cleanup operations. Likewise, high retention can be found in coarse sediments but also in sensitive shorelines like marshes. So these maps can be used as an operational tool to establish the priorities and to determine the best strategy for the shoreline cleanup methods (penetration maps), but also as an indicator of shoreline sensitivity (retention maps).

Biogeomorphological effects of leaf accumulations in stepped-bed channels: Exploratory study, Moravskoslezské Beskydy Mountains, Czech Republic

The stepped-bed system, with a step-like longitudinal profile, is typical morphology in steep headwater streams. These systems are created by a series of coarse sediments or instream wood (steps with supercritical flows) interspaced with finer material (forming pools with subcritical flows). In the case of well-developed steps and pools, the resulting channel-reach morphology is referred to as “step-pool” morphology. In this study, we identify a previously undescribed type of step-pool formation, the “foliaged step-pool”, in the high-gradient Stoligy Stream of the Moravskoslezské Beskydy Mountains. The defining feature of this formation is the significant presence of leaves in the step structure. The geometry of the steps and pools was measured and the parameters that characterise the distribution, amount and function of leaves acting in these areas were defined. Statistical results showed differences between non-foliaged and foliaged step-pool formations, in which the latter showed a significant increase in storage level, influencing the channel’s hydrodynamics. Particle-size analyses demonstrated that foliaged step-pool formations had finer sediment in the pools, which indicates that there are differences in sediment transport processes between foliaged and non-foliaged formations. These results offer new insights into stepped-bed and step-pool morphology, providing directions for further research on small streams in deciduous forested regions.