Kinetics of Mercury Bioaccumulation in the Polychaete Hediste diversicolor and in the Bivalve Scrobicularia plana, Through a Dietary Exposure Pathway

Mercury bioaccumulation kinetics of two important macrobenthic species, the polychaete Hediste diversicolor and the bivalve Scrobicularia plana, were evaluated following a dietary pathway (i.e. contaminated algae), through a mesocosm laboratory experiment. Both studied species presented a similar model of Hg bioaccumulation kinetics, a linear pattern of accumulation through time being the mercury accumulation in the organisms proportional to the mercury concentration in the food. Mercury bioaccumulation rates were higher in the polychaete H. diversicolor (reaching approximately 0.15 μg g⁻¹ at the end of the experiment) than in the bivalve S. plana (≈0.07 μg g⁻¹), which could be related to their feeding strategies, ingestion rates and assimilation efficiencies. Moreover, the mercury bioaccumulation revealed to be quite a fast process especially for the polychaete, and despite the fact that this species is not an edible organism, it is an important prey item, which can greatly contribute to the transport of contaminants to higher trophic levels. Therefore, the bioaccumulation of mercury by these important macrobenthic species, especially the bivalves, represents a non-negligible risk for humans.     

Espresso coffee residues: a valuable source of unextracted compounds

Espresso spent coffee grounds were chemically characterized to predict their potential, as a source of bioactive compounds, by comparison with the ones from the soluble coffee industry. Sampling included a total of 50 samples from 14 trademarks, collected in several coffee shops and prepared with distinct coffee machines. A high compositional variability was verified, particularly with regard to such water-soluble components as caffeine, total chlorogenic acids (CGA), and minerals, supported by strong positive correlations with total soluble solids retained. This is a direct consequence of the reduced extraction efficiency during espresso coffee preparation, leaving a significant pool of bioactivity retained in the extracted grounds. Besides the lipid (12.5%) and nitrogen (2.3%) contents, similar to those of industrial coffee residues, the CGA content (478.9 mg/100 g), for its antioxidant capacity, and its caffeine content (452.6 mg/100 g), due to its extensive use in the food and pharmaceutical industries, justify the selective assembly of this residue for subsequent use.