NUMERICAL MODELLING OF THE MORPHODYNAMICS OF THE PLOČE GRAVEL BEACH IN RIJEKA

The morphodynamics of an artificial gravel beach in the Bay of Rijeka (Ploče Beach) was analyzed. The morphological changes of the beach face were monitored through an intense situation of gravitational surface wind waves from the incident SSW direction. A numerical modeling technique was applied, after initially establishing a numerical model for wave deformation. A model for sediment transport was established based on its results. Both models were based on the finite volume method. In addition, the partial contribution of the longshore component of sediment transport was analyzed based on empirical formulae. The modeling results were verified by comparing the positions and amounts of eroded/accumulated material along the beach with the processing of terrain images in the form of point clouds. The erosion and accumulation positions of the beach sediment material, obtained by numerical model simulations, corresponded to the surveyed positions. The total volume of eroded and accumulated material based on terrain image processing corresponded to the model values.

Type and Distribution of Microplastics in Beach Sediment along the Coast of the Eastern Gulf of Thailand

In the oceans and coasts, plastic waste poses a global threat to biodiversity. This study examined the types and distribution of microplastics in beach sediment along the coast of the eastern Gulf of Thailand in March 2018 (northeast monsoon = dry season) and July 2018 (southwest monsoon = rainy season). Microplastic samples were collected from six stations including Koh Khramyai Beach (Chonburi Province), Koh Mannai Beach (Rayong Province), Chao Lao Beach (Chanthaburi Province, 3 stations), and Ploy Dang Beach (Trat Province). The results showed that the highest average abundances of microplastics in March and July were at Koh Mannai Beach (1698 pieces/m2) and Koh Khramyai Beach (799 pieces/m2), respectively. However, no microplastics were found at Ploy Dang Beach in July. According to polymer-type identification using an FTIR spectrometer, 17 polymer types were found in this study. Polyethylene terephthalate (PET = 39.6%) and polyamide (PA = 22.8%) were the polymer types found in the highest proportions in March and July, respectively. In addition, the fiber shape and transparent color of microplastics were found to be the most abundant.

Occurrence and distribution of microplastics in the beach sediment of Anday Beach, West Papua (Indonesia)

In the last two decades, scientists have extensively studied microplastics (MPs), small plastic pieces less than five millimeters long, which can be harmful to our ocean and aquatic life. The MPs in the environment came from the tiny particles designed for commercial use, such as cosmetics. The other sources come from the breakdown of larger plastic items. In this study, the occurrence and distribution of MPs were investigated in the Anday Beach of West Papua (Indonesia). The sampling was conducted from March to May 2019 on Anday Beach. The abundance of MPs found were 0.28 to 1 n/kg for MPs (1-5 mm) and 1140.6 to 1997.6 n/kg for MPs (< 1 mm). The highest abundance of MPs found on Anday Beach was plastic film. We suggest doing a regular beach clean-up to ensure the continuous assessment of marine litter in the coastal areas and extend the sampling area in Papua to record the plastic pollution status in the Papua.

Characterisation of microplastic debris in beach sediment of the coastal zone in Vietnam: A preliminary study in Da Nang

Microplastic (MP) pollution has become a global concern and a hot issue in Vietnam, especially along the coastal hydrosphere. The investigation was carried out by collecting the sediment samples from three typical urbanised beaches in Da Nang: My Khe, T20, and Son Thuy. The qualitative identification and quantitative analysis of MP samples were conducted using micro-Fourier-transform-infrared spectroscopy (μFTIR). A tailored analysis based on adaptation procedure of well-known ones was applied including 5 steps: (1) Drying and homogenising sediment sample; (2) Digestion and cleaning sediment sample; (3) MPs separation by the flotation; (4) MPs sample filtration; (5) MPs quantification and identification. The obtained data showed that the abundances of MPs at three beaches of Son Thuy, T20, and My Khe were 1,460±758, 1,799±370, and 29,232±2,577 items/kg dry sediment, respectively. MPs were classified by different sizes, in which the one with sizes being smaller than 150 μm was accounted for the highest proportion of 77.83% at Son Thuy, 87.96% at T20, and 65.91% at My Khe beach. The chemical composition of MPs with various polymers was precisely identified, in which three dominant polymers were determined as PTFE [Polytetrafluoroethylene (Teflon)], EVOH (Ethylene vinyl alcohol), and PA [Polyamide (Nylon)]. Preliminary results of MPs analysis in sediment samples of the three selected beaches in Da Nang can be interpreted as a solid basis for further investigation of MP debris in the shoreline, offshore, and other related samples towards conclusions about the sources of MP pollution in the marine environment in Vietnam’s coastal hydrosphere in future.

Disintegration half-life of biodegradable plastic films on different marine beach sediments

The seafloor is considered the major sink for plastic debris in the world’s oceans. Biodegradable polymers are available on the market as a substitute for conventional plastic and could potentially end up in the same environment. To gain more insight into the effects of different sediments on the degradation rate of biodegradable plastic we performed two iterative seawater tank experiments. First, to test the effect of sediment grain size, film of Mater-Bi HF03V, a blend of thermoplastic starch and biodegradable polyesters, was placed on the surface of mud as well as on four different grain size fractions of beach sand. Disintegration half-life was shortest on mud (139 days) and increased with the grain size of the beach sediment fractions (63–250 µm: 296 days; 250–500 µm: 310 days; 500–1,000 µm: 438 days; >1,000 µm: 428 days). We assume that the higher surface-to-volume ratio in fine sediment compared to coarse sediment led to a higher bacterial abundance and thus to faster disintegration rates. In a follow-up experiment, the <500 µm fraction of sediment from four different beaches around Isola d’Elba, Italy, was used to test plastic disintegration as above. Additionally, polyhydroxybutyrate (PHB, MIREL P5001) was used as a positive control and high-density polyethylene (HD-PE) as a negative control. No disintegration was observed for HD-PE. Mater-Bi HF03V and PHB disintegrated significantly differently on sediment from different sites, with half-lives of Mater-Bi HF03V ranging from 72 to 368 days and of PHB from 112 to 215 days. Here, the half-life was shortest on slightly coarser sediment and at potentially anthropogenically impacted sites. We assume that the effect of the grain size on the disintegration rate was masked by other parameters influencing the microbial community and activity. Understanding the parameters driving biodegradation is key to reliably report the range of disintegration rates occurring under the various conditions in different ecosystems.

A New Collection Tool-Kit to Sample Microplastics From the Marine Environment (Sediment, Seawater, and Biota) Using Citizen Science

Microplastics (plastic particles ≤ 5 mm) have been studied extensively in coastal areas around the world in several habitats. Nevertheless, understanding and explaining the temporal and spatial occurrence and dynamics of microplastics is challenging. For the first time, three environmental variables were studied at six locations at the same time for each season over a year, along the North and West coasts of Scotland. Surface water was collected with a pole water sampler from the shore whilst beach sediment was sampled using glass jars, and mussels were the target organism collected. Concentrations of microplastics ranged from 0 to 6 ± 1.50 particles per l of surface water. In beach sediment, microplastics concentrations ranged from 0 to 0.37 ± 0.12 particles per g.dw, whilst for mussels it ranged from 0 to 23.81 particles per g.ww. This study was designed to determine the presence of microplastics as well as extend the temporal and geographical scales. We developed a simple, cost-effective and practical tool-kit to collect microplastics from the coastal environment and engaged the public in scientific research. The tool-kit was designed to take into account the latest recommendations for sampling each environmental substrate, whilst being practical for citizen scientists to use. This research demonstrates that using a semi-structured to structured project with a defined sampling approach including the participation of the public with local knowledge can be an effective way to monitor microplastics in the marine environment along the Scottish coastline. This approach, can be adapted to other projects monitoring microplastics to increase the use of citizen science in projects, allowing more studies to take place, more samples to be collected, and a greater understanding of the occurrence and the potential impact of microplastics in the environment.