Small microplastic ingestion by the calanoid Centropages furcatus in the Gulf of Thailand.

Microplastics could be ingested by many organisms, including zooplankton, involving bioaccumulation and biomagnification mechanisms a cross food webs. The information about microplastic ingestion by zooplankton keeps increasing worldwide. However, it is still limited for particle sizes under 300 µm (small microplastics, SMPs) and in areas such as Southeast Asia, which is considered one of the hotspots for plastic debris. This study aimed to characterize the size, shape, and polymer types of the SMPs ingested by the copepod Centropages furcatus in Si Chang Island (upper Gulf of Thailand). The study spans offshore and coastal waters, with data collected across wet, intermediate, and dry seasons. Using a semi-automated technique for micro-FTIR (Fourier-transform infrared) scanning spectroscopy for particle analysis, we found ingested SMPs in all samples. A total of 750 individuals of the calanoid Centropages furcatus were analyzed, finding 309 plastic particles and an average ingestion value of 0.41 ± 0.13 particles ind-1, one of the highest recorded values. All the particles were fragments, with a predominant size under 50 µm, and polymer types as Polypropylene (PP, 71 %), followed by Ethylene-Propylene-Diene-Monomer (EPDM, 16 %) and Polyethylene (PE, 7 %). Up to 470.2 particles m-3 were estimated to be retained by this calanoid species and potentially available for trophic transfer. The effect of rainfall on SMPs ingestion was inconclusive, with a non-significant observed tendency to higher ingestion values near the coastal area than offshore area, suggesting a decrease in particle exposure due to the runoff effect. Nevertheless, future studies should increase the frequency of surveys to arrive at better conclusions.

Zooplankton as a suitable tool for microplastic research.

In recent years, significant efforts have been dedicated to measuring and comprehending the impact of microplastics (MPs) in the ocean. Despite harmonization guidelines for MPs research, discrepancies persist in the applied methodologies and future challenges, mostly for the smaller fractions (< 100 µm). Whether intentional or accidental, ingesting plastic particles by zooplankton can lead to incorporating this pollutant into aquatic food chains. Therefore, zooplankton can serve as a suitable proxy tool for assessing the presence of plastic particles in ocean waters. However, reliable information is essential for conducting experimental laboratory studies on the impact of MPs ingestion by zooplankton organisms. Using zooplankton as a research tool for MPs offers numerous advantages, including similar sampling methodologies and study techniques as MPs and particle data integration over space and time. The scientific community can gain novel perspectives by merging zooplankton studies with MPs research. This review explores key aspects of using zooplankton as a tool for MPs research in water samples, encompassing various views such as particles ingestion in natural environments, particle quantification in zooplankton samples (past and future), ecotoxicological and toxicology model studies. By leveraging the potential of zooplankton research, advancements can be made in developing innovative techniques for MPs analysis.

Plastic debris in lakes and reservoirs.

Plastic debris is thought to be widespread in freshwater ecosystems globally1. However, a lack of comprehensive and comparable data makes rigorous assessment of its distribution challenging2,3. Here we present a standardized cross-national survey that assesses the abundance and type of plastic debris (>250 µm) in freshwater ecosystems. We sample surface waters of 38 lakes and reservoirs, distributed across gradients of geographical position and limnological attributes, with the aim to identify factors associated with an increased observation of plastics. We find plastic debris in all studied lakes and reservoirs, suggesting that these ecosystems play a key role in the plastic-pollution cycle. Our results indicate that two types of lakes are particularly vulnerable to plastic contamination: lakes and reservoirs in densely populated and urbanized areas and large lakes and reservoirs with elevated deposition areas, long water-retention times and high levels of anthropogenic influence. Plastic concentrations vary widely among lakes; in the most polluted, concentrations reach or even exceed those reported in the subtropical oceanic gyres, marine areas collecting large amounts of debris4. Our findings highlight the importance of including lakes and reservoirs when addressing plastic pollution, in the context of pollution management and for the continued provision of lake ecosystem services.

A functional definition to distinguish ponds from lakes and wetlands.

Ponds are often identified by their small size and shallow depths, but the lack of a universal evidence-based definition hampers science and weakens legal protection. Here, we compile existing pond definitions, compare ecosystem metrics (e.g., metabolism, nutrient concentrations, and gas fluxes) among ponds, wetlands, and lakes, and propose an evidence-based pond definition. Compiled definitions often mentioned surface area and depth, but were largely qualitative and variable. Government legislation rarely defined ponds, despite commonly using the term. Ponds, as defined in published studies, varied in origin and hydroperiod and were often distinct from lakes and wetlands in water chemistry. We also compared how ecosystem metrics related to three variables often seen in waterbody definitions: waterbody size, maximum depth, and emergent vegetation cover. Most ecosystem metrics (e.g., water chemistry, gas fluxes, and metabolism) exhibited nonlinear relationships with these variables, with average threshold changes at 3.7 ± 1.8 ha (median: 1.5 ha) in surface area, 5.8 ± 2.5 m (median: 5.2 m) in depth, and 13.4 ± 6.3% (median: 8.2%) emergent vegetation cover. We use this evidence and prior definitions to define ponds as waterbodies that are small (< 5 ha), shallow (< 5 m), with < 30% emergent vegetation and we highlight areas for further study near these boundaries. This definition will inform the science, policy, and management of globally abundant and ecologically significant pond ecosystems.

Water quality analysis based on phytoplankton and metal indices: a case study in the Sauce Grande River Basin (Argentina).

The increasing landscape alterations due to anthropogenic activities is of global concern since it affects aquatic ecosystems, often resulting in compromise of the ecological integrity and the water quality. In this sense, the evaluation, monitoring, and prediction of the aquatic ecosystem quality becomes an important research subject. This study presents the first integrated water quality assessment of the Sauce Grande River Basin, in Argentina, based on the spatial distribution of the phytoplankton community, the physicochemical parameters, and the metal concentrations (Cd, Cu, Cr, Fe, Mn, Ni, Pb, and Zn) found in the particulate fraction. According to the trophic indices and the phytoplankton abundance, composition, and diversity, the water quality showed significant deterioration in the lower basin after the Sauce Grande lake. The trophic state index indicated that water was oligotrophic in over 75% of the sampling sites, increasing downstream, where two sites were characterized as mesotrophic, and one described as hypertrophic. The phytoplankton community was dominated by diatoms in zones with low anthropogenic impact and conductivity, whereas high densities of Euglenophyta, Chlorophyta, and Cyanobacteria were found in the middle-lower basin, associated with higher organic matter and eutrophication. The conductivity, turbidity, and most metal concentrations also increased towards the downstream area, even exceeding recommended levels for the metals Cu, Cr, Mn, and Pb in the middle and lower reaches of the basin (Cu: 3.5 µg L-1; Cr: 2.4 µg L-1; Pb: 1.2 µg L-1; Mn 170 µg L-1). This study generates a database for the water quality of the Sauce Grande River Basin and sets an example of how the water quality varies along a basin that crosses different topographic environments, land covers, and anthropogenic influences.

Synthetic microfibers and tyre wear particles pollution in aquatic systems: Relevance and mitigation strategies.

Evidence shows that the majority of aquatic field microplastics (MPs) could be microfibers (MFs) which can be originated directly from massive sources such as textile production and shedding from garments, agricultural textiles and clothes washing. In addition, wear and tear of tyres (TRWPs) emerges as a stealthy major source of micro and nanoplastics, commonly under-sampled/detected in the field. In order to compile the current knowledge in regards to these two major MPs sources, concentrations of concern in aquatic environments, their distribution, bulk emission rates and water mitigation strategies were systematically reviewed. Most of the aquatic field studies presented MFs values above 50%. MPs concentrations varied from 0.3 to 8925 particles m-3 in lakes, from 0.69 to 8.7 × 106 particles m-3 in streams and rivers, from 0.16 to 192000 particles m-3 estuaries, and from 0 to 4600 particles m-3 in the ocean. Textiles at every stage of production, use and disposal are the major source of synthetic MFs to water. Laundry estimates showed an averaged release up to 279972 tons year-1 (high washing frequency) from which 123000 tons would annually flow through untreated effluents to rivers, streams, lakes or directly to the ocean. TRWPs in the aquatic environments showed concentrations up to 179 mg L-1 (SPM) in runoff river sediments and up to 480 mg g-1 in highway runoff sediments. Even though average TRWR emission is of 0.95 kg year-1 per capita (10 nm- 500 µm) there is a general scarcity of information about their aquatic environmental levels probably due to no-availability or inadequate methods of detection. The revision of strategies to mitigate the delivering of MFs and TRWP into water streams illustrated the importance of domestic laundry retention devices, Waste Water Treatment Plants (WWTP) with at least a secondary treatment and stormwater and road-runoff collectors quality improvement devices.

Microplastics pollution in salt pans from the Maheshkhali Channel, Bangladesh.

Microplastics (MP) were recognized as an emergent pollution problem due to their ubiquitous nature and bioaccumulative potential. Those present in salt for consumption could represent a human exposure route through dietary uptake. The current study, conducted in Bangladesh, reports microplastics contamination in coarse salt prepared for human consumption. Sea salt samples were collected from eight representative salt pans located in the country's largest salt farming area, in the Maheshkhali Channel, along the Bay of Bengal. Microplastics were detected in all samples, with mean concentrations ranging from 78 ± 9.33 to 137 ± 21.70 particles kg-1, mostly white and ranging in size from 500-1000 µm. The prevalent types were: fragments (48%) > films (22%) > fibers (15%) > granules and lines (both 9%). Fourier transform mid-IR and near-IR spectra (FT-MIR-NIR) analysis registered terephthalate (48%), polypropylene (20%), polyethylene (17%), and polystyrene (15%) in all samples. These results contribute to the MP's pollution knowledge in sea salts to understand and reduce this significant human exposure route and environmental pollution source in the future.

Microplastics on plankton samples: Multiple digestion techniques assessment based on weight, size, and FTIR spectroscopy analyses.

Digestion protocols are needed to determine microplastics abundance and features. This study assessed the organic matter (OM) digestion efficiency on plankton samples and the MPs' weight, size, and polymer changes under different digestion techniques. For this, 2-step (KOH and H2O2 + Fe2+) and 3-step (2-step and enzymes) digestion techniques were assessed under different duration and temperature conditions. The results obtained for OM digestion with 2-step and 3-step techniques were satisfactory. Weight changes were registered for polyethylene terephthalate (PET), polystyrene foam, polyvinyl chloride, and polycarbonate with 2-step digestion, but with inconsistent values. Significant size changes were registered only for PET applying 2-step digestion techniques at 60 °C. Using 40 °C for 72 h prevailed all polymers from size changes. Polyethylene weathered MPs were also preserved, including an enzymatic step. Polymer fingerprints were not affected by any digestion technique. Based on these results, any method applying high temperatures will damage MPs.

Continental microplastics: Presence, features, and environmental transport pathways.

Microplastics (MPs) are ubiquitous contaminants of great concern for the environment. MPs' presence and concentration in the air, soil, marine, and freshwater environments have been reported as a matter of priority in recent years. This review addresses the current knowledge of the main pathways of MPs in air, soil, and freshwater reservoirs in order to provide an integrated understanding of their behaviors in the continental environment. Therefore, MPs' occurrence (as particle counts), sources, and how their features as shape, size, polymer composition, and density could influence their transport and final sink were discussed. Wind resuspension and atmospheric fallout, groundwater migration, runoff from catchments, and water flow from rivers and effluents were pointed as the principal pathways. MPs' size, shape, polymer composition, and density interact with environmental variables as soil structure and composition, precipitation, wind, relative humidity, water temperature, and salinity. Sampling designs for MPs research should further consider soil characteristics, climate variability and extreme events, time lag and grasshopper effects, morphological and hydrological features of aquatic systems, and water currents, among others. Furthermore, long-term monitoring and lab experiments are still needed to understand MPs' behavior in the environment. This information will provide a unified understanding of the continental MPs pathways, including the key main findings, knowledge gaps, and future challenges to understand this emerging contaminant.

Assessing threats, regulations, and strategies to abate plastic pollution in LAC beaches during COVID-19 pandemic.

Plastic use and production have dramatically increased globally over the past 65 years with the improvement of life quality by the daily use of plastic products. Still, around 50% of the plastic produced is disposable products that generate substantial waste. Several reports pointed out the adverse effects of plastic litter in coastal environments in recent years, emphasizing single-use plastics (SUP). In this manner, Latin America and the Caribbean (LAC) coastal environments are highly vulnerable due to wastewater treatment facilities scarcity and poor plastic waste management strategies. Since COVID-19 pandemic, the single-use plastic waste/person rate is expected to rise due to the use of personal protective equipment and SUP as health care measures. Based on literature research and the review of plastic waste regulations, this paper will assess the main COVID-19 plastic pollution threats and LAC beaches' regulations to suggest possible measures to abate this problem. The main findings suggest that unifying the ongoing fragmented and overlapped policies is key to abate plastic pollution, including plastic industry regulations and circular economies. In addition, increasing public risk perception about plastic pollution is critical to reducing plastic waste generation. Research advances in the adverse effects of plastic debris could improve the public's perception of plastic pollution risk, pushing forward global marine plastic governance.