Microplastic ingestion in key fish species of food webs in the Southwest Atlantic (Marine Protected Area Namuncurá / Burdwood Bank).

Microplastics (MPs) are currently one of the main problems of marine pollution, being found in all environmental matrices. Due to their size, they can be ingested by organisms directly (from the environment) or indirectly (with their prey). The objective of this study was to analyze the occurrence, abundance, concentration, and chemical nature of MPs present in the gastrointestinal tract of two fish species, Patagonotothen guntheri and Patagonotothen ramsayi, both of which are key in the food web of the Marine Protected Area Namuncurá/ Banco Burdwood (MPA N/BB). The analyzed species presented high values of MPs per individual (MPs/ind.) and occurrence compared to other studies. P. guntheri tended to have a lower number of MPs/ind. and occurrence than P. ramsayi (P. guntheri: 2.50 ± 1.93 MPs/ind., 82.50  %; P. ramsayi: 3.93 ± 2.91 MPs/ind., 90.60  %). While fibers were the predominant MPs in both species, P. ramsayi had a greater number of fragments and a greater variety of MPs chemical composition than P. guntheri. The prevailing chemical composition was cellulosic material (cellulose and cellulose mixed with polyamide and polyester). Synthetic fibers and fragments such as polyester (PET), alkyd resin, polyurethane, polyethylene, polyacrylic fiber and poly(ethylene-co-vinyl acetate-co-vinyl chloride) were also found. Although both species have a generalist diet, the differences found may be due to the fact that P. guntheri has benthopelagic feeding habits while P. ramsayi has demersal-benthic. Our study is the first report on the presence and characterization of MPs in organisms relevant to food webs in the Southwest Atlantic.

Riboflavin and Eosin Y Supported on Chromatographic Silica Gel as Heterogeneous Photocatalysts.

The application of photocatalysis for organic synthesis, both in the laboratory and on an industrial scale, will depend on the achieving of good yields and the ease with which it can be applied. Selective irradiation of the photocatalyst with LED light has made it possible to activate the reactions easily, without the need for UV or heat filters. However, a common problem is the need to separate the photocatalyst from the reaction products through extraction and chromatography isolation processes. These procedures make it difficult to recover and reuse the catalyst, which is not compatible with scale-up applications. Photocatalysts attached to heterogeneous supports resulted in an alternative, which facilitates their removal and reuse. In this study, we use chromatographic silica gel as a low-cost heterogeneous support to bind photosensitizers such as Riboflavin or Eosin Y. The modified silica gel was analyzed by FTIR-ATR and diffuse reflectance UV-visible spectroscopy, thermogravimetric analysis, and optical microscopy. These hybrid materials have a suitable size for easy separation by decantation and were found to be photoactive against two photooxidation reactions. These easy-to-handle materials open the door to effective applications for photoinduced organic synthesis methods at medium to large scale.

Microplastics distribution in river side bars: The combined effects of water level and wind intensity.

Rivers are the main pathway for microplastics (MP) transport toward the ocean. However, the understanding of the processes involved in the deposition and mobilization of MP in rivers, specifically in sediment side bars (SB), remains very limited. The objectives of this study were: (i) to examine the effect of hydrometric fluctuations and wind intensity on the distribution of microplastics (MP < 5 mm) in the SB of large river (the Paraná River), (ii) to determine the characteristics of MP to infer their origin and fate, and (iii) to discuss potential similarities or differences between MP suspended in the water column and MP found in sediment. The SB and water column were sampled during the autumn, winter, and spring of 2018, and the summer of 2019 at different river discharges and wind intensities. >90 % of the MP items found were fiber of polyethylene terephthalate (PET; FT-IR analysis), the most common MP color was blue, and most were in the 0.5-2 mm size range. The concentration/composition of MP varied according to the river discharge and wind intensity. During the falling limb of the hydrograph when discharge is decreasing and sediments are exposed for short periods (13-30 days), MP particles transported by the flow were deposited on temporarily exposed SB, accumulating there in high densities (309-373 items/kg). However, during the drought, when sediments remained exposed for a long time (259 days), MP were mobilized and transported by the wind. During this period (no influence of the flow), MP densities significantly decreased on SB (39-47 items/kg). In conclusion, both hydrological fluctuations and wind intensity played a significant role in MP distribution in SB.

Plastic Impacts in Argentina: a Critical Research Review Contributing to the Global Knowledge.

PURPOSE OF REVIEW: Plastic pollution research has experienced exponential growth in the last decade; however, Argentina concentrates more than 70% of their research in the last 4 years. This review compiles regional research on plastic pollution in water, soil, sediment, air and organisms in Argentina. It discusses current sampling, quantification, and plastics identification methodologies while analyzing levels, gaps, and opportunities. RECENT FINDINGS: Research in plastic pollution was mainly focused on the biosphere component (52.9%), followed by the hydrosphere component (29.4%), and finally the lithosphere component (17.7%), with less than 20% addressing multiple components simultaneously. Sixty percent of this research was focused around microplastics, and less than 20% have considered multiple plastic debris sizes. Marine coastal species from Argentina had higher levels of microplastics than organisms from other South American studies, while microfibers were identified in 100% of the freshwater organisms studied. The lowest microplastic concentrations were found in lakes and in the Paraná and La Plata rivers, while the maximum concentrations were found in Pampa´s streams. There was a lack of standardization in methodology and unit expression in studies of sediment microplastics, which hinders comparison between reports. Argentine scientists have created the national alliance called SciEnce for Plastic Impacts Argentina (SEPIA). SEPIA is a network which aims to systemize plastic pollution research, coordinate methodologies, and enhance relationships with decision-makers, NGOs, and the general public. A time gap was found between the designation of principal international multilateral agreements and the implementation of national regulations for plastic waste treatment, with a tendency to include advanced concepts as Extended Producer Responsibility and Circular Economy.

Microplastics pollution in the intertidal limpet, Nacella magellanica, from Beagle Channel (Argentina).

Microplastics (MPs) have been identified in diverse marine invertebrates; however, there are few studies on limpets. This study aimed to evaluate and compare the presence of MPs in Nacella magellanica among sites of the Beagle Channel with different degree of anthropogenic influence. Intertidal limpets were sampled in three sites: Ushuaia Bay (UB) (inside Ushuaia city), a site with high anthropogenic influence owing to population growth, and fisheries, industrial and port activities; Ensenada Zaratiegui (EZ) and Playa Larga (PL) (west and east of Ushuaia city, respectively), both sites with a certain degree of environmental protection and low anthropogenic influence. MPs were isolated from the whole soft tissue of individuals by oxidative digestions with H2O2 (30%; 1:10 w/v). MPs occurrence was 100% in organisms from UB and EZ, whereas 90% in PL. Limpets from UB showed 10 ± 6.69 MPs/ind and 2.22 ± 0.78 MPs/g ww, while in PL and EZ there were 2.90 ± 2.02 MPs/ind and 0.96 ± 0.94 MPs/g ww; and 5.60 ± 2.59 MPs/ind and 2.41 ± 1.47 MPs/g ww, respectively. Fibres were the most abundant MPs type, followed by fragments and films. Fibres and films were identified as semi-synthetic cellulose and, although the polymer matrix of fragments was masked by copper phthalocyanine, one of them could be identified as polystyrene. As expected, the highest abundance of MPs was found in UB. However, a lower abundance of particles was detected in PL (downstream of UB) than in EZ (upstream of UB). This could be due to the influence of both the main current of the Beagle Channel and fluvial discharges, reducing the buoyancy of MPs. More studies are needed to understand the contribution of regional and local features to the accumulation of MPs in these environments and their interaction with the biota.

First report of microplastics presence in the mussel Mytilus chilensis from Ushuaia Bay (Beagle Channel, Tierra del Fuego, Argentina).

Microplastics contamination is reported for the first time on Mytilus chilensis from Ushuaia Bay, one of the most remote areas of South America. Our results demonstrate the occurrence of microplastics in all samples, with an average of 8.6 ±â€¯3.53 items per individual. Fibers and fragments were the most abundant, with a percentage of 77.91 and 17.44%, respectively. The average length of the fibers was 742.3 ±â€¯702.1 µm, while the average cross-sectional area of fragments was 1944.80 ±â€¯960.94 µm2. The polymers identified were polyamides, semi-synthetic cellulosic materials, and PVC copolymers. The number of microplastics per individual was greater than those reported in even more populated regions. Probably, the modifications included in the technique led to optimize the extraction of MPs, reflecting the detection of a greater number of particles. M. chilensis could play a role in an extensive evaluation of MPs in the Ushuaia Bay, providing information on the interaction of MPs and biota.

Atmospheric Photo-oxidation of Diethyl Carbonate: Kinetics, Products, and Reaction Mechanism.

The rate coefficient for the gas phase of diethyl carbonate with chlorine atoms has been determined at 298 K using a relative method, employing ethyl formate and ethyl acetate as reference compounds. The experimental value, (1.0 ± 0.2) × 10-11 cm3 molecule-1 s-1, is in good correlation with the one estimated by the SAR (Structure-Activity Relationship) method. The photo-oxidation mechanism of diethyl carbonate initiated by chlorine atoms was also studied at 298 K and atmospheric pressure as a function of the oxygen partial pressure. The main products identified by infrared spectroscopy were CH3CH2OC(O)OCHO, CH3CH2OC(O)OCH2CHO, CH3CH2OC(O)OC(O)CH3, CO2, CO, HCOOH, and CH3COOH. The results reveal that the oxidation process occurs by the abstraction of a hydrogen atom from the methyl (43%) and methylene (57%) groups. The relative importance of each reaction path from the primary radicals formed in photo-oxidation and the identity of CH3CH2OC(O)OCHO, CH3CH2OC(O)OC(O)CH3, and CH3CH2OC(O)OCH2CHO were determined using computational methods. The activation energy of reaction paths for the main oxygenated radicals formed during photo-oxidation was determined using Gaussian09 Program.

Photo-oxidation of Dimethyl Malonate Initiated by Chlorine Atoms in Gas Phase: Kinetics and Mechanism.

The rate coefficient for the gas-phase reaction of chlorine atoms with dimethyl malonate (DMM, CH3OC(O)CH2C(O)OCH3) was determined at 298 K using relative methods giving a value of (3.8 ± 0.4) × 10-12, cm3 molecule-1 s-1). The photo-oxidation mechanism of DMM was also investigated. The main products were identified by infrared spectroscopy, and computational calculations were performed in order to support the experimental data. The results reveal that the photo-oxidation occurs mainly by the abstraction of an H atom from the methyl groups. The CH3OC(O)CH2C(O)OCH2O• radical formed subsequently reacts according to three competitive paths: reaction with molecular oxygen to yield CH3OC(O)CH2C(O)OC(O)H, isomerization-unimolecular decomposition to lead finally to CH3OC(O)C(O)H, CO2, and HC(O)OH, and α-ester rearrangement to form monomethyl malonate and carbon monoxide. The yield of products as a function of oxygen pressure was also determined.