Asian clam Corbicula fluminea as potential biomonitor of microplastics and metal(oid)s in a Patagonian River.

This study summarizes the concentration in dry weight (dw) of several metal(oid)s (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn), as well as the abundance and characteristics of microplastics (MP) in wet weight (ww) of the soft tissues of clam Corbicula fluminea from Chubut River (Patagonia, Argentina). The contents of essential elements were in the following decreasing order: Zn > Mn > Cu > Ni; meanwhile, non-essential elements Cd, Cr and Pb were below the detection limit (<0.5 µg/g dw). A high mean concentration of As (6.1 ± 0.3 µg/g dw) was found, surpassing the maximum allowable limit established by the Argentine Food Code for bivalve molluscs. The number of MP ranged from 0.07 to 1.27 items/ind. and from 0.2 to 2.9 items/g ww. Fibers were the most common shape, mainly transparent. The size of MP ranged from 42 to 1917 µm, accounting for 62 % of MP between 50 and 450 µm. The dominant polymer was PET based on the results of Raman spectroscopy. Based on the widespread distribution of MP in the environment and the wide range of effects on organisms, it is necessary to develop long-term monitoring programs for MP contamination in different environmental matrices. Understanding the bioaccumulation of MP in bivalves is crucial to assess the potential risk to human health through consumption and to the ecosystem. We propose that the widespread Asian clam could serve as a useful biomonitor for MP and As pollution in freshwater and estuarine environments such as the Chubut River.

Biomarkers in the freshwater bivalve Corbicula fluminea confined downstream a domestic landfill leachate discharge.

Landfills represent a severe environmental problem mainly due to the generation of leachates, and this study aimed to evaluate sublethal effects of a domestic landfill leachate in the freshwater bivalve Corbicula fluminea. Clams were submitted to in situ tests along a stream, at three sites, representing increasing distances from the leachate discharge (Pq1, Pq2, and Pq3), for 1, 5, and 15 days. The following biomarkers were analyzed in the gills and digestive glands: 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities, multixenobiotic resistance mechanism (MXR), total antioxidant capacity (TAC), reactive oxygen species (ROS), and lipid peroxidation (LPO). Metallothionein (MT) content was determined in the gills and DNA damage in hemocytes. The mortality rate of animals during in situ tests was reduced as the distance from the leachate discharge source increased. On the other hand, biomarker results showed sublethal effects on C. fluminea confined at all sites of PqS. GST, TAC, ROS, and DNA damage were the most significant biomarkers for this species and should be considered for future monitoring and assessment of freshwater environments located in landfill areas.

Chromium accumulation in the Asian clam, Corbicula fluminea (Müller, 1774), as an indicative of landfill leachate contamination.

The Asian clam Corbicula fluminea exposed in situ for periods of 1, 5, 15 and 30 days along a stream which receives landfill leachate effluent showed increased Cr accumulation in gills and digestive gland, although Cr concentrations have been found to be low in sediment. Other metals such as Pb, Ni, Al and Cu were also analyzed but were found to accumulate in clam tissues in lower concentrations or without showing a consistent pattern. Thus, the accumulation of a single contaminant such as Cr is proposed to be used as a tool to assess exposure to a complex mixture such as landfill leachates.

The influence of lead on different proteins in gill cells from the freshwater bivalve, Corbicula fluminea, from defense to repair biomarkers.

The objective of this study was to evaluate the influence of lead (Pb) on regulatory proteins linked to mechanisms of animal adaptation to polluted environments (using in vivo and in vitro tests) and to validate the in vitro assay as a tool for environmental assessment. Specimens of the bivalve Corbicula fluminea were exposed to nominal concentrations of Pb 5 mg l(-1) for 96 h. Isolated gill cells were exposed to three concentrations (1, 10, and 100 µM) for 5 h. Metal toxicity was evaluated by cell viability (trypan blue exclusion). We also analyzed Na+/K+ adenosine triphosphatase (ATPase) and carbonic anhydrase activity. Additionally, the multixenobiotic-resistance (MXR) phenotype was evaluated by the accumulation of rhodamine B (RB). Immunolabeling was used to quantify the expression of P-glycoproteins (C219) and proteins involved in ion transport, water movement, and cellular repair using antibodies against Na+/K+ ATPase, aquaporin 1, and heat-shock protein 70 (Hsp70). Pb was shown to be toxic in both in vivo and in vitro tests, in which cellular viability significantly decreased by approximately 25%. Cellular viability in the in vivo assays was determined by gill cell isolation after the entire animal was exposed to Pb. We observed that Na+/K+ ATPase activity was inhibited by 70%. Also, the expression of the MXR phenotype significantly increased in our in vivo tests. A statistically significant difference was observed in the expression of all proteins in the in vitro assays, whereas only Hsp70 increased in vivo. Employing these analyses, we could validate the sensitivity of the in vitro tests and can propose our in vitro model as a possible tool for environmental assessment.

Assessment of ametryn contamination in river water, river sediment, and mollusk bivalves in São Paulo state, Brazil.

São Paulo state, Brazil, is one of the main areas of sugar cane agriculture in the world. Herbicides, in particular, ametryn, are extensively used in this extensive area, which implies that this herbicide is present in the environment and can contaminate the surface water by running off. Thereby, residues of ametryn were analyzed in samples of river water an river sediment and in freshwater bivalves obtained from the rivers Sapucaí, Pardo and Mogi-Guaçu in São Paulo State, Brazil. Samples were taken in the winter of 2003 and 2004 in two locations in each river. The specimens of freshwater bivalves collected and analyzed were Corbicula fluminea, an exotic species, and Diplodon fontaineanus, a native species. Additionally, the evaluation of the ability of bioconcentration and depuration of ametryn by the freshwater bivalve Corbicula fluminea was also performed. Ametryn concentrations in the samples were measured by liquid chromatography coupled to mass spectrometry. Residues of ametryn in water (50 ng/L) and in freshwater bivalves (2-7 ng/g) were found in the Mogi-Guaçu River in 2004, and residues in river sediments were found in all rivers in 2003 and 2004 (0.5-2 ng/g). The observation of the aquatic environment through the analysis of these matrixes, water, sediment, and bivalves, revealed the importance of the river sediment in the accumulation of the herbicide ametryn, which can contaminate the biota.

Bioaccumulation of atrazine in freshwater bivalves Anodontites trapesialis (Lamarck, 1819) and Corbicula fluminea (Müller, 1774).

The bioaccumulation of atrazine in bivalves is expected due to its wide use in agriculture and its moderate water solubility (33 mg/l). To assess the capacity of bioaccumulation, we performed a laboratory study in which two bivalves species (Anodontites trapesialis and Corbicula fluminea) were exposed to atrazine (concentrations of 0.06 to 0.34 microg/ml) during 48 h. The results showed that both bivalve species were able to bioaccumulate atrazine in their tissues. In another experiment, groups of bivalves from the specie A. trapesialis were exposed to atrazine at the concentration of 1 mug/ml and different organs of these animals were analyzed. The visceral mass, foot and mantle plus siphon showed the highest values of atrazine bioaccumulation.