Bioaccumulation of trace metals in the plastisphere: Awareness of environmental risk from a European perspective

The term "Plastisphere" refers to the biofilm layer naturally formed by microorganisms attaching to plastic surfaces. This layer possesses the capability to adsorb persistent organic and inorganic pollutants, particularly trace metals, which are the focus of this research study. Immersion experiments were concurrently conducted in five locations spanning four European countries (France, Ireland, Spain, and Italy) utilising eight distinct polymers. These immersions, repeated every three months over a one-year period, aimed to evaluate the baseline bioaccumulation of 12 trace metals. The study underscores the intricate nature of metal bioaccumulation, influenced by both micro-scale factors (such as polymer composition) and macro-scale factors (including geographical site and seasonal variations). Villefranche Bay in France exhibited the lowest metals bioaccumulation, whereas Naples in Italy emerged as the site where bioaccumulation was often the highest for the considered metals. Environmental risk assessment was also conducted in the study. The lightweight nature of certain plastics allows them to be transported across significant distances in the ocean. Consequently, evaluating trace metal concentrations in the plastisphere is imperative for assessing potential environmental repercussions that plastics, along with their associated biota, may exert even in locations distant from their point of emission.

Proximity to coast and major rivers influence the density of floating microplastics and other litter in east African coastal waters

Floating anthropogenic litter occurs in all ocean basins, yet little is known about their distribution and abundance in the coastal waters off east Africa. Neuston net and bulk water sampling shows that meso- and micro-litter (8567 ± 19,684 items∙km^-2, 44 ± 195 g∙km^-2) and microfibres (2.4 ± 2.6 fibres∙L^-1) are pervasive pollutants off the coasts of Tanzania and northern Mozambique, with higher litter loads off Tanzania. Densities of meso- and micro-litter at the start of the rainy season were greater close to the coast and to major river mouths, suggesting that much litter likely originates on land. However, the mass of litter increased with distance from the six major coastal cities. By number, 95% of meso- and micro-litter was plastic, but only 6% of microfibres. Our results highlight the need to reduce plastic use and improve solid waste management in the region.

Diversity and predicted inter- and intra-domain interactions in the Mediterranean Plastisphere

This study investigated the biogeography, the presence and diversity of potentially harmful taxa harbored, and potential interactions between and within bacterial and eukaryotic domains of life on plastic debris in the Mediterranean. Using a combination of high-throughput DNA sequencing (HTS), Causal Network Analysis, and Scanning Electron Microscopy (SEM), we show regional differences and gradients in the Mediterranean microbial communities associated with marine litter, positive causal effects between microbes including between and within domains of life, and how these might impact the marine ecosystems surrounding them. Adjacent seas within the Mediterranean region showed a gradient in the microbial communities on plastic with non-overlapping endpoints (Adriatic and Ligurian Seas). The largest predicted inter-domain effects included positive effects of a novel red-algal Plastisphere member on its potential microbiome community. Freshwater and marine samples housed a diversity of fungi including some related to disease-causing microbes. Algal species related to those responsible for Harmful Blooms (HABs) were also observed on plastic pieces including members of genera not previously reported on Plastic Marine Debris (PMD).

Impact of Microbial Colonization of Polystyrene Microbeads on the Toxicological Responses in the Sea Urchin Paracentrotus lividus

The sea urchin Paracentrotus lividus (P. lividus) was exposed to either virgin or biofilm-covered polystyrene microbeads (micro-PS, 45 μm) in order to test the effect of microbial colonization on the uptake, biodistribution, and immune response. The biofilm was dominated by bacteria, as detected by scanning electron microscopy and 16S rRNA sequencing. A higher internalization rate of colonized micro-PS inside sea urchins compared to virgin ones was detected, suggesting a role of the plastisphere in the interaction. Colonized and virgin micro-PS showed the same biodistribution pattern by accumulating mainly in the digestive system with higher levels and faster egestion rates for the colonized. However, a significant increase of catalase and total antioxidant activity was observed only in the digestive system of colonized micro-PS-exposed individuals. Colonized micro-PS also induced a significant decrease in the number of coelomocytes with a significant increase in vibratile cells, compared to control and virgin micro-PS-exposed animals. Moreover, a general time-dependent increase in the red/white amoebocytes ratio and reactive oxygen species and a decrease in nitrogen ones were observed upon exposure to both colonized and virgin micro-PS. Overall, micro-PS colonization clearly affected the uptake and toxicological responses of the Mediterranean sea urchin P. lividus in comparison to virgin micro-PS.

Supplementation of Acqua Lete® (Bicarbonate Calcic Mineral Water) improves hydration status in athletes after short term anaerobic exercise

BACKGROUND

Experimental studies suggest that mineral waters with high concentrations of calcium and bicarbonate can impact acid-base balance. The purpose of this study was to test the effect on acid-base balance and specific urine gravity, of a bicarbonate calcic mineral water (Acqua Lete®) compared to a minimally mineralized water.

METHODS

88 amateur male athletes underwent two experimental trials with a modified Wingate test: the first was carried out without hydration (Control Test, Test C, n = 88); the second was carried out after one week of controlled hydration (Test with hydration, Test H, n = 88), with 1.5 L/day of a very low mineral content water (Group A, n = 44) or 1.5 L/day of Acqua Lete® (Group B, n = 44). Measure of body temperature, bioimpedance analysis, muscular ultrasound, and urinalysis were taken before (t0), immediately after (t1), 5' (t2), and 30' (t3) after exercise.

RESULTS

Hydration results in a decreased core temperature; muscular ultrasound showed increased muscle thickness after exercise related to content of body water. Regarding urinalysis, in test H, we found in both groups after exercise a significant decrease of specific urine gravity with significantly lower levels in Group B. We also found a significant increase of pH in the same Group B.

CONCLUSIONS

In conclusion all the athletes hydrated with Acqua Lete® showed a positive impact on hydration status after anaerobic exercise with significant decrease of specific urine gravity and a positive effect on pH.