The proposed project is based on experimental studies in systems from small aquaria (microcosms) to large systems (mesocosms). All experiments will be executed at HCMR facilities in Crete ( The strategy will be to test out the effects of ENPs in simple systems (microcosms) and the selected treatments from the results to test in mesocosms.

Two different mesocosm treatments will be performed. In the first treatment, Silver nanoparticles will be added to the mesocosms (3 replicates). In the second experiment the synergistic effects of ENPs in combination with the presence of others toxic organic compound such us polycyclic aromatic hydrocarbons (PAHs) will be exanimate. Due to chemical composition, surface charge and high specific surface area, some ENPs may have a large capacity to adsorb both inorganic and organic pollutants. One important topic is therefore how nanoparticles may influence mobility, bioavailability and degradation of potentially harmful compounds in the environment (PAHs, heavy metals, etc.). In this treatment Silver nanoparticles and a mixture of PAHs will be added to mesocosms (3 replicates). Prior the experiment the Silver nanoparticles will be fully characterized and small scale experiments will be performed in order to estimate the physicochemical characteristics. In addition to the two treatments, three more mesocosms will be used as control. The experiment will last 8-10 days and the abiotic changes and biotic responses will be measured by assessed.

Investigating the Behavior of Metal-containing Nanoparticles (NP) in Seawater Environments will be performed using Single-Particle Inductively Coupled Plasma Mass Spectrometry. When investigating the behavior of metal-containing NPs in a seawater environment it is imperative to determine several different NP characterization metrics. Relevant analytical metrics include measuring NP size distribution, number concentration, and metal mass fraction, for the NPs occurring in both the seawater and in marine biota. Increases in NP size may indicate NP aggregation or interaction with other naturally occurring particles, whereas decrease in NP size indicates their dissolution. Determining NP number concentrations for the duration of the experiment provides information relevant to NP cycling within the system, i.e. information about NP stability and uptake by marine organisms. Changes in the metal mass fraction of each NP may also reveal the occurrence of processes such as metal dissolution. Also, when combining size data with their corresponding metal mass fraction one can arrive at useful information regarding the interaction of the metal-containing NPs with other components or particles occurring in the investigated seawater system. Finally, detection of NP within the examined marine organisms provides valuable evidence of NP uptake within living organisms. Subsequent analysis could reveal their further biotransformation, ultimately giving us information about overall toxicity.

In this study we propose the use of single-particle (SP) inductively coupled plasma mass spectrometry (ICP-MS) for measuring engineered metal-containing NP metrics at the ultratrace level in seawater and biota samples. SP-ICP-MS has recently been demonstrated to be suitable for the simultaneous determination of the concentration of metal-containing NPs (NP number concentration) and the metal mass fraction in individual NPs (Degualdre, et al., 2004; Degueldre and Faverger, 2004; Moserud et al., 2009; Mitrano et al., 2012). Also, we have just reported on the development of a hyphenated analytical technique for the detection and characterization of metal-containing NPs, i.e. their metal mass fraction, size and number concentration (Pergandis et al ., 2012). Hydrodynamic chromatography (HDC), suitable for sizing NPs within the range of 5 to 300 nm, was coupled on-line to ICP-MS providing for an extremely selective and sensitive analytical tool for the detection of NPs. More specifically, SP – ICP-MS coupled on-line HDC was developed as an analytical approach suitable for simultaneously determining NP size distribution, NP number concentration and NP metal content.