A non-lethal SPME-LC/MS method for the analysis of plastic-associated contaminants in coral reef invertebrates

Current approaches to evaluate microplastic contamination of the marine environment include the use of marine organisms as bioindicators and the detection of plastic-associated contaminants in their tissues. Liquid/liquid extraction and/or solid-phase extraction are the usual methods of choice for sample preparation. However, these methods suffer from background contamination, due to the large volume of solvents used and the ubiquity of plasticizers in laboratory environments. Moreover, organisms used in the study may belong to species that are rare or endangered and these should preferably not be sacrificed as a consequence of the relatively sizeable biological material required for exhaustive sample extractions and the destructive nature of mass spectrometry analysis. In this study, we evaluated, as a non-lethal alternative, a procedure involving solid phase microextraction (SPME) coupled with liquid chromatography mass spectrometry (LC/MS) analysis. Two coral reef invertebrates that may be sensitive to microplastic contamination were used for the tests, i.e., the scleractinian Danafungia scruposa and the bivalve mollusk Tridacna maxima. The results showed that the method was effective in quantifying phthalate esters within ten minutes of exposure, offering at the same time an improved control of the background contamination compared to the classical extraction procedure

Nitrogen activation of carbon-encapsulated zero-valent iron nanoparticles and influence of the activation temperature on heavy metals removal

Nanoparticles of zero-valent iron (nZVI) represent a promising agent for environmental remediation. This is due to their core-shell structure which presents the characteristics of both metallic and oxidised iron, leading to sorption and reductive precipitation of metal ions. Nevertheless, nZVI application presents some limitations regarding their rapid oxidation and aggregation in the media which leads to the delivery of the ions after some hours (the "aging effect"). To address these issues, modifications of nZVI structure and synthesis methods have been developed in the last years. The aging problem was solved by using nZVI encapsulated inside carbon spheres (CE-nZVI), synthetized through Hydrothermal Carbonization (HTC). Results showed high heavy metals removal percentage. Furthermore, CE-nZVI were activated with nitrogen in order to increase the metallic iron content. The aim of this study was to test CE-nZVI post-treated with nitrogen at different temperatures in heavy metals removal, demonstrating that the influence of the temperature was negligible in nanoparticles removal efficiency.This work was financially supported by University of Milano-Bicocca fund (2016-ATESP-0597) and University of Alicante (UAFPU2013-5791)

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements