Metabolic Responses of Mytilus galloprovincialis to Fullerenes in Mesocosm Exposure Experiments.

In this study, Mediterranean mussels (Mytilus galloprovincialis) were exposed through the diet to fullerene soot at three concentrations in parallel to a control group. Their metabolomics response was assessed by high-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC-HRMS). The experiments were conducted in marine mesocosms, during 35 days (7 days of acclimatization, 21 days of exposure, and 7 days of depuration). Real conditions were emulated in terms of physicochemical conditions of the habitat. Results confirmed the bioaccumulation of fullerenes, and the metabolome of the exposed organisms revealed significant differences in the concentrations of seven free amino acids in comparison to the control group. An increase in small nonpolar amino acids (e.g., alanine) and branched chain amino acids (leucine and isoleucine) were observed. Also, glutamine concentrations decreased significantly, suggesting the activation of facultative anaerobic energy metabolism. Branched chain amino acids, such as leucine and isoleucine, followed the opposite trend after the highest level of exposure, which can imply hormesis effects. Other significant differences were observed on lipids content, such as the general increase of free fatty acids, i.e., long-chain fatty acids (lauric, myristic, and palmitic acids) when the concentration of exposure was increased. These results were consistent with hypoxia and oxidative stress.

New Insights on the Influence of Organic Co-Contaminants on the Aquatic Toxicology of Carbon Nanomaterials.

At present, there is a lack of understanding of the combined ecotoxicity of carbon-based nanomaterials and co-contaminants. In this paper, we report on the toxicity of three carbon nanomaterials (fullerene-soot, multiwall carbon nanotubes, and graphene). Two standardized toxicity bioassays, the immobilization of the invertebrate Daphnia magna and the bioluminescence inhibition of the marine bacteria Vibrio fischeri, have been used. Synergistic and antagonistic effects of binary mixtures composed of fullerene soot and organic co-contaminants as malathion, glyphosate, diuron, triclosan, and nonylphenol were assessed. The isobologram method was used to evaluate the concentrations producing an effect, in comparison to those effects expected by a simple additive approach. In this study, antagonism was the predominant effect. However, synergism was also observed as in the case of D. magna exposed to mixtures of malathion and fullerene soot. D. magna was shown to be the most sensitive assay when carbon nanomaterials were present. Toxicity to D. magna was as follows: fullerene soot > multiwall carbon nanotubes > graphene. These results were proportional to the size of aggregates, smaller aggregates being the most toxic. The vector function of nanomaterials aggregates and the unexpected release inside living organisms was proven for malathion. These results highlight new insights on the risks associated with the release of carbon nanomaterials into the environment.

Development of a multiresidue method for analysis of pesticides in sediments based on isotope dilution and liquid chromatography-electrospray-tandem mass spectrometry.

Because of the complexity of the sediment matrix, selective methods are necessary to identify and quantify different kinds of pesticides at a time. In this context, a multiresidue method based on isotope dilution and final analysis by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS) was developed for the determination of 26 pesticides and transformation products in sediment. The method developed comprises pressurized liquid extraction (PLE) and further purification of the extract by solid phase extraction (SPE) prior to analysis. In the process of method optimization various SPE cartridges as well as PLE and SPE elution solvents were evaluated. Due to the relatively high volatility of some compounds (e.g., propanil), special attention was paid to the evaporation step. Experiments comparing different pressures and times during solvent evaporation were performed with the aim to improve the recovery of these compounds. Matrix effects were also studied even though they were corrected through the use of 23 deuterated compounds as surrogate standards for quantification. The analytical method developed showed good validation parameters in terms of linearity, sensitivity (limits of detection in the pgg(-1) or low ngg(-1) range and limits of determination below 80ngg(-1)), accuracy (relative recoveries between 92 and 118%, except for malaoxon (66.5%)), and repeatability (relative standard deviations between 1.5 and 17%, for all compounds except the acidic herbicides). Its main advantage is the simultaneous analysis of pesticides with a large variety of physical-chemical properties, as well as its improved accuracy due to the use of the isotope dilution method. Application of the method to the analysis of 5 real samples from 4 different Spanish rivers revealed the presence of 5 of the 26 target compounds, being chlorpyrifos, diuron and diazinon the most ubiquitous, as expected, due to their high bioaccumulation and low mobility features.