Josep Ángel Sanchís Sandoval
Nanotechnology is the multidisciplinary science consisting in modifying the matter at the nanometre scale. Due to the unique properties exhibited by nanomaterials, the number of investigations devoted to obtain new materials and their applications has increased dramatically. However, the potential risk associated to nanomaterials and nanostructures continues being poorly understood. Different gaps of information were identified including their environmental occurrence, fate, behaviour and toxicity. In addition, some nanomaterials can also be emitted by natural events or incidental sources. Under this context, this doctoral Thesis presents the study of the occurrence and toxicity of nanomaterials and nanostructures in the environment, focusing on pristine and functionalized fullerenes and volatile dimethylsiloxanes. Different extraction procedures for the analysis of pristine and functionalized fullerenes in different environmental compartments were developed: (i) For the investigation of their occurrence in air particulate two extraction procedures are presented, based on ultrasound assisted solvent extraction with toluene with recoveries from 60 to 70 %, and using accelerated solvent extraction with recoveries ranging from the 70 to 113 %; (ii) for the investigation of soils using a long-term ultrasound assisted solvent extraction with toluene; (iii) for the simultaneous analysis of fullerenes in the particulate and dissolved phases of water samples. Two analytical methods based on liquid chromatography coupled to mass spectrometry for the analysis of fullerenes in environmental samples were developed. The first one employed C18 analytical column with toluene:methanol as mobile phase and an ESI source in negative ionization conditions coupled to a triple quadrupole analyzer. The second method consisted in the use of pyrenylpropyl stationary phase columns with toluene as mobile phase. LC was coupled to HRMS with an APPI source. The main improvements of the second approach were in terms of lower matrix effect, better sensibility and selectivity. The occurrence of pristine and non-polar functionalized fullerenes was evaluated in several compartments. - Air particulate: The concentrations of C60 ranged from 10 pg/m3 to 50 ng/m3 in the Mediterranean Sea atmosphere, and between the MLOQ and 63 pg/m3 in air particulate of Barcelona city. - Soils: Samples were taken in Saudi Arabia and Brazil, close to potential emission points. The concentrations of pristine fullerenes were in the pg/g–ng/g levels, showing the incidental emission these compounds and subsequent deposition. - Freshwater and sediments from the Llobregat River. The relationship between the occurrence of natural colloids and the sedimentation of fullerenes because of heteroaggregation and flocculation was studied. Pristine fullerenes were detected in all the compartments while functionalized fullerenes were detected very rarely. The results show that incidental combustion sources are the main contributor to the environment, in contrast to nanotechnology. The occurrence of siloxanes was studied in several environmental compartments. According to our results the intensive manufacture and application of cVMS such as in personal care products, industry, nano-emulsions, etc. lead to the emission of these compounds at global-scale: - Wastewater: Siloxanes were detected in almost all influent and effluent samples at concentrations up to 24 µg/L. In general, for VMS relevant elimination rates during WW treatments were shown. - Fish: Fish directly sampled in the Xúquer River and fish for human consumption collected in different markets stores were analysed. Market fish presented higher levels, which can be attributed to contamination during food manipulation, storage and ambient air. - Samples from the Antarctic region: VMS were found in all types of the analyzed samples (krill, phytoplankton, soil and vegetation). These results reveal for first time the potential long-range environmental transport of VMS and their posterior cool-deposition supported by the snow scavenging during winter time and their posterior liberation to sea water and soils during the Antarctic summer. The acute toxicity of carbon nanomaterials (fullerene soot, carbon nanotubs and graphene) dispersed in artificial estuary medium in ecologically relevant conditions was studied using two standardized acute toxicity tests. The results are to fullerenes aggregation in presence of humic acid and salts. The presence of fullerene soot is relevant because inhibited the activity of most of the organic co-contaminants due to their sorption properties.
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