Composition Of Debris Research Articles

Abundance and composition of near surface microplastics and plastic debris in the Stockholm Archipelago, Baltic Sea

We collected plastic debris in the Stockholm Archipelago using a manta trawl, and additionally along a transect in the Baltic Sea from the island of Gotland to Stockholm in a citizen science study. The samples were concentrated by filtration and organic material was digested using hydrogen peroxide. Suspected plastic material was isolated by visual sorting and 59 of these were selected to be characterized with Fourier transform infrared spectroscopy. Polypropylene and polyethylene were the most abundant plastics identified among the samples (53% and 24% respectively). We found nearly ten times higher abundance of plastics near central Stockholm than in offshore areas (4.2×105plastics km−2 compared to 4.7×104plastics km−2). The abundance of plastic debris near Stockholm was similar to urban areas in California, USA, and the overall abundance in the Stockholm Archipelago was similar to plastic abundance reported in the northwestern Mediterranean Sea.

Tribological properties and mechanisms of self-mated ultrafine-grained titanium

While titanium and its alloys have an excellent balance of properties, they continue to have limited applications owing to their relatively poor wear resistance, in particular for commercially pure titanium. Processing by severe plastic deformation (SPD) has been developed over the last two decades that produces an ultrafine-grained (UFG) microstructure resulting in improved mechanical properties. However, only limited studies are available to date on the wear behavior of SPD-processed UFG metallic materials with many conflicting results in terms of reduced wear rates. Furthermore, the wear behavior and mechanisms of SPD-UFG metallic materials are unknown in self-mated sliding contacts. Here, the friction and wear properties of self-mating UFG titanium in a cross-cylinder high frequency reciprocating contact is reported and compared to coarse grain (CG) titanium. Cross-sectional focused ion beam microscopy, transmission electron microscopy, and Raman spectroscopy studies were performed inside worn surfaces to determine the dry sliding wear-induced structural and chemical evolution responsible for the observed friction coefficients and wear rates. It was determined that the microhardness of UFG titanium increased from 2.6 to 3.4GPa; however, this increased hardness did not correlate to lowering of friction and wear. Instead, the similar friction coefficients and wear rates of CG titanium and UFG titanium were due to similar wear surface structures and oxide debris composition. Furthermore, wear surface morphologies and cross sections inside the wear tracks revealed that CG titanium had a major shear deformation contribution to wear, but with the wear rates being equivalent, wear is most likely dominated by oxide particle abrasion.

Investigation of Transition in Sliding Wear Resistance of Nickel based Zinc Alloy

The wear transition behaviour and wear debris are significant parameters in understanding the wear behaviour of ZA alloys. The purpose of the paper was to investigate the effect of Ni on wear and wear transition of Ni based ZA modified alloy. The wear experiments were conducted under dry conditions and load ranging from 10-150 N and sliding speed from 1.25 to 10 m/s. Composition of worn surfaces and wear debris were analysed by energy dispersive X-ray spectrometer (EDS) and X-ray diffractometer (XRD). A mild wear and severe wear regions have been observed during conduction of the experiment. The wear debris mixture constitute during a mild wear especially in modified alloy. The wear debris mixture influenced a key role in reducing the wear loss and also delaying the severe wear. The severe plastic deformation was observed during the transition stage. The wear mechanisms in each stage were analysed and categorised on the basis of EDS and XRD observation.

Marine litter abundance and distribution on beaches on the Isle of Rügen considering the influence of exposition, morphology and recreational activities

The abundance, weight and composition of marine debris were determined at the northwest coast of the Isle of Rügen in 2015. A total number of 1115 macrolitter items were registered, resulting in an abundance of 304±88.96 items per 100m of beach length and therefore being greater than the abundances found for other beaches at the Baltic Sea. Macrolitter items were predominantly composed of plastic, on average 83%. The four beaches under investigation have different exposition as well as touristic levels. The differing influence of wind and water currents as well as recreational activities on the macrolitter at these beaches was detectable. The distribution of items within a beach segment was analyzed by implementing D-GPS and drone aerial photography. The results of this analysis suggested that the identity of the substrate as well as the presence of vegetation are both major influencing factors in the macrolitter distribution.

Sources, composition and spatial distribution of marine debris along the Mediterranean coast of Israel

Marine debris (litter) is a complex problem that affects human activities and the marine environment worldwide. The Clean Coast Program in Israel has had some success in keeping most of the coasts clean most of the time, but without understanding the mechanisms of accumulation of marine debris on the coasts of Israel. In 2012, we initiated a study to characterize the types of marine debris, its origins and spatial distribution. Nineteen surveys were done from June 2012 to March 2015 on eight beaches that spanned the coast of Israel. Average debris density was 12.1 items per 100m2 and 90% of the items were plastic. The top debris categories were food wrappers and disposables, plastic bags and cigarette butts. However, there was variation in the top debris categories among the beaches indicating that a flexible approach with multiple options will be important when addressing the marine debris problem.

Phenomenological Analysis of Melt Progression in LWRS: Proposal of an In-Vessel Corium Progression Scenario in the Unit 1 of Fukushima Dai-ichi Nuclear Power Plant

In the field of severe accident, the description of corium progression events is mainly carried out using integral calculation codes. However, these tools are usually based on bounding assumptions because of the high complexity of phenomena. The limitations associated with bounding situations [1] (e.g., steady-state situations and instantaneous whole core relocation in the lower head) led CEA to develop an alternative approach to improve the phenomenological description of the melt progression. The methodology used to describe the corium progression was designed to cover the accidental situations from the core meltdown to the molten core–concrete interaction (MCCI). This phenomenological approach is based on the available data (including learnings from TMI-2) on physical models and knowledge about the corium behavior. It provides emerging trends and best-estimate intermediate situations. As different phenomena are unknown, but strongly coupled, uncertainties at large scale for the reactor application must be taken into account. Furthermore, the analysis is complicated by the fact that these configurations are most probably three-dimensional (3D), all the more so because 3D effects are expected to have significant consequences for the corium progression and the resulting vessel failure. Such an analysis of the in-vessel melt progression was carried out for the Unit 1 of the Fukushima Dai-ichi Nuclear Power Plant. The core uncovering kinetics governs the core degradation and impacts the appearance of the first molten corium inside the core. The initial conditions used to carry out this analysis are based on the available results derived from codes such as the MELCOR calculation code [2]. The core degradation could then follow different ways: (1) Axial progression of the debris and the molten fuel through the lower support plate, or (2) lateral progression of the molten fuel through the shroud. On the basis of the Bali program results [3] and the TMI-2 accident observations [4], this work is focused on the consequences of a lateral melt progression (not excluding an axial progression through the support plate). Analysis of the events and the associated time sequence will be detailed. Besides, this analysis identifies some number of issues. Random calculations and statistical analysis of the results could be performed with calculation codes such as LEONAR–PROCOR codes [5]. This work was presented in the frame of the OECD/NEA/CSNI Benchmark Study of the Accident at the Fukushima Dai-ichi Nuclear Power Station (BSAF) project [6]. During the years of 2012 and 2014, the purpose of this project was both to study, by means of severe accident codes, the Fukushima accident in the three crippled units, until 6 days from the reactor shutdown, and to give information about, in particular, the location and composition of core debris.

Ubiquitous Nature of Distal Athero/Thromboembolic Events during Lower Extremity Atherectomy Procedures Involving the Superficial Femoral Artery

This study aims to evaluate occurrence, size, composition, and clinical significance of embolized debris during superficial femoral artery atherectomy using all commercially available atherectomy devices. Distal athero/thromboembolic events (DATE) are a universal phenomenon in lower extremity atherectomy procedures (LEAPs) due to the sheer volume of atheroma and the thrombus burden in peripheral arterial disease. Some of these events can be clinically significant. We prospectively gathered clinical and histopathological data on all commercially available atherectomy devices by using embolic protection devices (EPD) in every case. After intervention, the contents of EPD were examined both microscopically and macroscopically. Data from 59 consecutive patients undergoing LEAP were analyzed. DATE occurred 100% of the time. The composition of particulate debris varied with the device used. Grossly visible agglomerated debris was captured by the filter in the majority of patients 54/59 (91.5%). Clinically significant debris, defined by the Preventing Lower Extremity Distal Embolization Using Embolic Filter Protection registry as particle diameter > 0.2 cm, was found in 33/59 (56%) patients. The size of captured debris particles ranged from 0.1 to 2.4 mm. While DATE occurred in all patients, clinically significant DATE occurred in 56% patients undergoing LEAP regardless of the atherectomy device. In spite of a large fraction of the clinically significant debris occurring on our routine dual antiplatelet regimen, no patient suffered an amputation. Although DATE was prevented by the use of EPD in all 59 cases, more data are needed to determine whether the use of EPD translates into a long-term clinical benefit. Use of EPD and optimal thromboprophylaxis should be considered in patients, especially in the setting of compromised distal runoff.

The preliminary assessment of abundance and composition of marine beach debris in the northern Persian Gulf, Bandar Abbas City, Iran

Marine debris is a major challenge threatening ocean and coastal environment with no easy solution in coming years. The problem is totally manmade and extendeds to coastal areas around the world. The accumulation of marine debris is largely due to lack of awareness and environmental education among the public reinforced with mismanagement of municipal litter in coastal cities. Iran has about 2415 km of coastlines in the north and south of the country that suffer severely from a marine debris problem. Despite the great scale of the problem that leads to the shutdown of some beaches to beachgoers, there are no documented data on the abundance, composition and sources of marine debris dispersed on beaches. With the cooperation of marine biology student volunteers, we surveyed beaches at two scales, 100 m and 1 km searching for litter in varying ranges. The results revealed that the most common items are made of plastic/polystyrene. Tourism and recreational activities are responsible for more than 90% of litter production on the study beach. Fisheries and aquaculture are the second source of most abundant marine litter found on the beach with considerable distance from tourism activities. We conclude that lack of education about the consequences of marine litter is the main reason for marine debris at the study beach. Another reason is related to rapid construction of coastal areas and development of coastal cities with no proper infrastructure to manage municipal littering.

Changes in the composition of ichthyoplankton assemblage and plastic debris in mangrove creeks relative to moon phases.

Lunar influence on the distribution of fish larvae, zooplankton and plastic debris in mangrove creeks of the Goiana Estuary, Brazil, was studied over a lunar cycle. Cetengraulis edentulus, Anchovia clupeoides and Rhinosardinia bahiensis were the most abundant fish larvae (56·6%), independent of the moon phase. The full moon had a positive influence on the abundance of Gobionellus oceanicus, Cynoscion acoupa and Atherinella brasiliensis, and the new moon on Ulaema lefroyi. The full and new moons also influenced the number of zoeae and megalopae of Ucides cordatus, protozoeae and larvae of caridean shrimps, and the number of hard and soft plastic debris, both <5 and >5 mm. Micro and macroplastics were present in samples from all 12 creeks studied, at densities similar to the third most abundant taxon, R. bahiensis. Cetengraulis edentulus and R. bahiensis showed a strong positive correlation with the last quarter moon, when there was less zooplankton available in the creeks and higher abundance of microplastic threads. Anchovia clupeoides, Diapterus rhombeus, U. lefroyi and hard microplastics were positively associated with different moon phases, when calanoid copepods, Caridean larvae and zoeae of U. cordatus were highly available in the creeks. Cynoscion acoupa, G.oceanicus and A. brasiliensis were strongly associated with the full moon, when protozoeae of caridean shrimps and megalopae of U. cordatus were also highly available, as were hard and soft macroplastics, paint chips (<5 mm) and soft microplastics. The results reinforce the role of mangrove creeks as nursery habitats. The moon phases influenced the distribution of fish larvae species, zooplankton and plastic debris by changing their compositions and abundances in the mangrove creeks of the Goiana Estuary when under the influence of different tidal current regimes.

Marine debris surveys on four beaches in Rizhao City of China

ABS TRACT: Compared with USA, UK, Brazil, Indonesia, Australia, etc., marine debris research in China has received less attention and few studies have attempted to quantify the abundance and mass of marine debris. In this paper, the abundance, composition and source of beached marine debris, and debris collection system and frequency as well as dustbins’ conditionwere investigated in Duodaohai, Wanpingkou, Shanhaitian and National Forest Park beaches of Rizhao City from June 1 to 10, 2013. Based on these surveys, following conclusions were obtained: In four coastal beaches surveyed, the mean number and weight densities were 25.91 items/100m 2 and 341.39 g/100m 2 , respectively. Most of the beached marine debris in the aforementioned beaches originated directly from land sources. There were two kinds of debris collection systems in these beaches at present; dustbins sometimes were not enough to be used in the swimming period.We hope that our study will be helpful to raise the level of environmental consciousness among people and to expand their anti-debris activities .

Evaluation of predictive tools for cell culture clarification performance.

Recent advances in the productivity of industrial mammalian cell culture processes have resulted in part in increased cell density. This increase and the associated increase in cellular debris are known to challenge harvest operations, however this understanding is limited and largely qualitative. Part of the issue arises from the heterogeneous size and composition of cellular debris, which makes harvest feed stream extremely difficult to characterize. Improved characterization methods would facilitate the development of clarification approaches that are consistent and scalable. This work describes how both particle size and cholesterol analysis can be used to characterize the feed stream. Particle size analysis by focused beam reflectance and dynamic light scattering are shown to be predictive of centrate filterability under certain harvest conditions. Because of the particle size range limitations of each detector, their applicability is limited to a particular stage or method of clarification. The measurement of cholesterol present in the cell culture supernatant or centrate was successfully used in providing relative amount of lysed cellular debris and enabled us to predict clarification performance of acid precipitated harvest regardless of particle size distribution profile.

Climate Warming and Soil Carbon in Tropical Forests: Insights from an Elevation Gradient in the Peruvian Andes.

The temperature sensitivity of soil organic matter (SOM) decomposition in tropical forests will influence future climate. Studies of a 3.5-kilometer elevation gradient in the Peruvian Andes, including short-term translocation experiments and the examination of the long-term adaptation of biota to local thermal and edaphic conditions, have revealed several factors that may regulate this sensitivity. Collectively this work suggests that, in the absence of a moisture constraint, the temperature sensitivity of decomposition is regulated by the chemical composition of plant debris (litter) and both the physical and chemical composition of preexisting SOM: higher temperature sensitivities are found in litter or SOM that is more chemically complex and in SOM that is less occluded within aggregates. In addition, the temperature sensitivity of SOM in tropical montane forests may be larger than previously recognized because of the presence of “cold-adapted” and nitrogen-limited microbial decomposers and the possible future alterations in plant and microbial communities associated with warming. Studies along elevation transects, such as those reviewed here, can reveal factors that will regulate the temperature sensitivity of SOM. They can also complement and guide in situ soil-warming experiments, which will be needed to understand how this vulnerability to temperature may be mediated by altered plant productivity under future climatic change.

New model to explain tooth wear with implications for microwear formation and diet reconstruction

Paleoanthropologists and vertebrate paleontologists have for decades debated the etiology of tooth wear and its implications for understanding the diets of human ancestors and other extinct mammals. The debate has recently taken a twist, calling into question the efficacy of dental microwear to reveal diet. Some argue that endogenous abrasives in plants (opal phytoliths) are too soft to abrade enamel, and that tooth wear is caused principally by exogenous quartz grit on food. If so, variation in microwear among fossil species may relate more to habitat than diet. This has important implications for paleobiologists because microwear is a common proxy for diets of fossil species. Here we reexamine the notion that particles softer than enamel (e.g., silica phytoliths) do not wear teeth. We scored human enamel using a microfabrication instrument fitted with soft particles (aluminum and brass spheres) and an atomic force microscope (AFM) fitted with silica particles under fixed normal loads, sliding speeds, and spans. Resulting damage was measured by AFM, and morphology and composition of debris were determined by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Enamel chips removed from the surface demonstrate that softer particles produce wear under conditions mimicking chewing. Previous models posited that such particles rub enamel and create ridges alongside indentations without tissue removal. We propose that although these models hold for deformable metal surfaces, enamel works differently. Hydroxyapatite crystallites are "glued" together by proteins, and tissue removal requires only that contact pressure be sufficient to break the bonds holding enamel together.

Quantities and composition of shore debris along Clifton Beach, Karachi, Pakistan

Debris abundance and composition were investigated for the first time along the most popular beach (Clifton Beach) of Karachi, Pakistan, which is one of the most populous cities of the world. The surveys were conducted in June, July and August 2013 to estimate the number and the weight of 10 predetermined types of debris along the beach front of Karachi. The 3-month average quantities of the debris collected from the designated transects of Clifton Beach were 2216 ± 371 counts in number and 13.71 ± 2.15 kg in weight. The quantities of beach debris were estimated at 8865 ± 1483 items km−1, with a corresponding weight of 54.83 ± 8.58 kg km−1. In terms of number, plastic was the most abundant debris along the beach (50.5 % of the total counts), which was followed by food (7.5 %) and paper (6.6 %) while, in terms of weight, processed wood was the most abundant debris on the beach (25.5 % of the total), which was followed by plastic (19.9 %) and metal (9.8 %). Plastic items were significantly higher (p < 0.001) than any other type of debris on the beach during all the 3 months. The predetermined types of debris were also classified on the basis of their sizes. Metal, glass, paper, plastic and rubber items were largely smaller in size while styro-foam, masonry, processed wood and cloth items were mostly larger in size. The main sources of debris were restaurants, cafes and hawkers, which served food, beverages and mild stimulants in plastic, polystyrene and aluminum foil to the beach visitors. Furthermore, the major part of floating debris from Lyari and Malir rivers were ultimately deposited along the shoreline of Karachi.

Recreational activities impact on the amount and characteristics of woody debris in the Fandoghlou forests, Northwestern Iran

Abstract In this research, the volume and composition of woody debris (WD) were inventoried by line intersect sampling (LIS) in recreational and conservative parts of Fandoughlou forests in Northwestern Iran. Based on the pre-study qualitative assessments of WD properties, 60 transects in conserved part including 60 ha tract and 60 transects in recreational part including 60 ha and 60 transects were set up for WD survey. In each area, a systematic series of sampling points was located in the inventory of WD. At each sampling point, we performed line-intersect sampling (LIS) with a line length of 100 m with random orientation of sample lines. Estimates of the total volume of WD across recreational and conservative parts of the forest ranged from 0.70 m3 ha-1 to 1.49 m3 ha-1. The results of independent t-test indicated that the amount of CWD and FWD in conserved part is significantly higher than CWD and FWD in recreational part (t4, 0.05 = 4.26, p = 0.013; t4, 0.05 = 2.69, p = 0.05). The number of tree species of CWD composition was higher in conserved area, more than 5 species including (hazel, beech, hornbeam, oak, maple, and other species). In the conserved part, CWD in highly-decayed classes accounted for 75% of total CWD volumes, but in the recreational division, CWD in the early decayed classes accounted for 79% of total WD volumes. Our results suggest preserving the current conserved forests and maintaining the structural and functional integrity of WD.

Composition and potential origin of marine debris stranded in the Western Indian Ocean on remote Alphonse Island, Seychelles

The abundance, composition, and potential sources of marine debris were investigated on remote Alphonse Island, during the austral winter 2013. A total of 4743 items, weighing 142kg, were removed from 1km of windward beach, facing the prevailing southeasterly trade winds. Our study demonstrates the prevalence of plastic debris as a world-wide marine contaminant. Characteristics of the debris suggest it originated primarily from land-based sources. To determine their potential geographic sources we used the Surface Current from Diagnostic model of near-surface ocean currents, forced by satellite sea level and wind data. While preliminary evidence indicated the Southeast Asia to be the main source of the flotsam, the model highlighted Somalia as another potential primary source. Our study concludes that most of the collected debris entered the sea as a result of inadequate waste management and demonstrates how anthropogenic waste can negatively impact even the most remote environments.

Changes in abundance and composition of anthropogenic marine debris on the continental slope off the Pacific coast of northern Japan, after the March 2011 Tohoku earthquake

Abundance and composition of anthropogenic marine debris were assessed on the basis of six bottom trawl surveys conducted on the continental slope off Iwate Prefecture, Pacific coast of northern Japan, in 2003, 2004 and 2011, and the temporal changes due to the Tohoku earthquake and tsunami in March 2011 evaluated. In 2003 and 2004, 54–94 items km−2 of marine debris, dominated by sea-base sourced items mainly comprising fishing gear and related items from adjacent fishing grounds on the continental shelf, were quantified. In the post-earthquake period, the density increased drastically to 233–332 items km−2, due to an increase in land-base sourced items generated by the tsunami. However, a major increase in abundance after the disaster, compared to the total amount of tsunami debris swept into the sea, was not found. Additional sources of land-based debris from the adjacent continental shelf are suggested in the present waters.

Perte de masse et transformation de débris de bois enfouis dans le sol en milieu tropical humide

Woody inputs in agroecosystems can enhance physiso-chemical properties of soil, however decomposition kinetics of these fresh inputs have been rarely studied in tropical humid regions. In Amazonia, this practice occurs for fire-free forest clearing, and could contribute to carbon storage in soil. In this study we aimed to assess the fate of woody debris buried in soil, in an experimental site located in French Guiana, fire-free cleared and cultivated. Decomposition kinetic of woody debris &gt; 4 mm was assessed by mass loss measurements, until 4 years after deforestation. Organic matter composition of woody debris was analysed over time with Rock-Eval pyrolysis, allowing us to distinguish two carbon pools in this woody debris, one labile and one resistant. Woody debris &gt; 4 mm decomposed with a first-order kinetic, and its half-life was 17,6 months. During the first year after its burying, the C : N ratio, R400, and hydrogen index of woody debris significantly decreased, showing that processes of decarboxylation and dehydrogenation occurred. Labile carbon stocks and resistant carbon stocks both decreased with a first-order decay, with a half-life slightly lower for labile carbon. This indicates a low humification and the absence of long term preservation of woody debris. This study suggests that benefits of woody inputs for soil properties in a humid tropical climate only occur the first year following deforestation.

Palaeotopography and its Constraint on the Development of Depositional Facies Period of Early Cretaceous in Tabei

Based on well logging and seismic calibration, the approximate paleo-level method was used to recreate the palaeotopography before deposition of Yageliemu stage, and then the study area was subdivided into three geomorphic units, high uplift, slope and depression. The braided river delta, oxidized shallow water delta, bank-bars as well as lacustrine sedimentary systems were identified through cores, mineralogy and logging data. Via debris composition, heavy mineral, seismic property studies, the lateral distribution of sedimentary systems were identified. This research revealed that the source to sink systems in study area are obviously controlled by topography, and there are two source districts, uplift and south-east, and braided river delta sediments developed in both the south and north sides of the eroded paleo-unplift. The southeastern source lack sediments supply, therefore only small oxidized shallow delta developed.

Pathophysiology of flow impairment during carotid artery stenting with an embolus protection filter

Carotid artery stenting (CAS) is a well-accepted treatment for atherosclerotic stenosis of carotid arteries. Since the occurrence of distal embolization with CAS is still a major concern embolus protection devices (EPD) are usually employed during the procedure. We examined two types of embolus protection filters (Angioguard XP (AG); Filterwire EZ (FW)) and evaluated the function. Thus, the filter was examined postoperatively and the cause of intraoperative flow impairment was evaluated. CAS was performed for 54 patients with carotid artery stenosis (55 lesions: 25 AG; 27 FW; 3 others). After completing CAS the filter membrane was stained with hematoxylin-eosin (HE) solution and removed from the filter strut. Once mounted on a glass slide the filter was evaluated under a microscope. The area occupied with debris was measured and the relationship to intraoperative flow impairment was evaluated. Furthermore, the relationship between perioperative ischemic complications and intraoperative flow impairment was statistically analyzed. Microscopic observation of the slide revealed the pore density of the FW was 1.5 times higher than that of the AG and the filter area of the FW was 2.5 times wider than than the AG. HE staining facilitated characterization of the debris composition. The area occupied with debris was significantly more in the AG (0.241 ± 0.13 cm(2)) than in the FW (0.129 ± 0.093 cm(2)). Thus, fibrin was significantly more precipitated in the AG. Flow impairment occurred in 6 AG cases (24.0 %) and 4 FW cases (14.8 %). It was induced by filter obstruction in the AG and by vasospasms in the FW. Three cases treated with AG (12.0 %) were complicated with cerebral infarction and all of them were related to flow impairment. One FW case (3.7 %) was complicated with cerebral infarction in presence of preserved flow throughout the intervention. Filter function is different according to each design. The cause of flow impairment was attributable to filter obstruction in the AG group and to vasospasms in the FW group. Filter obstruction tends to result in cerebral infarction.