Direct Injection Liquid Chromatography High-Resolution Mass Spectrometry for Determination of Primary and Secondary Terrestrial and Marine Biomarkers in Ice Cores

Many atmospheric organic compounds are long-lived enough to be transported from their sources to polar regions and high mountain environments where they can be trapped in ice archives. While inorganic components in ice archives have been studied extensively to identify past climate changes, organic compounds have rarely been used to assess paleo-environmental changes, mainly due to the lack of suitable analytical methods. This study presents a new method of direct injection HPLC-MS analysis, without the need of pre-concentrating the melted ice, for the determination of a series of novel biomarkers in ice-core samples indicative of primary and secondary terrestrial and marine organic aerosol sources. Eliminating a preconcentration step reduces contamination potential and decreases the required sample volume thus allowing a higher time resolution in the archives. The method is characterised by limits of detections (LODs) in the range of 0.01-15 ppb, depending on the analyte, and accuracy evaluated through an interlaboratory comparison. We find that many components in secondary organic aerosols (SOA) are clearly detectable at concentrations comparable to those previously observed in replicate preconcentrated ice samples from the Belukha glacier, Russian Altai Mountains. Some compounds with low recoveries in preconcentration steps are now detectable in samples with this new direct injection method significantly increasing the range of environmental processes and sources that become accessible for paleo-climate studies

Secondary organic aerosol formation from isoprene photooxidation during cloud condensation-evaporation cycles

Abstract. The impact of cloud events on isoprene secondary organic aerosol (SOA) formation has been studied from an isoprene ∕ NOx ∕ light system in an atmospheric simulation chamber. It was shown that the presence of a liquid water cloud leads to a faster and higher SOA formation than under dry conditions. When a cloud is generated early in the photooxidation reaction, before any SOA formation has occurred, a fast SOA formation is observed with mass yields ranging from 0.002 to 0.004. These yields are 2 and 4 times higher than those observed under dry conditions. When the cloud is generated at a later photooxidation stage, after isoprene SOA is stabilized at its maximum mass concentration, a rapid increase (by a factor of 2 or higher) of the SOA mass concentration is observed. The SOA chemical composition is influenced by cloud generation: the additional SOA formed during cloud events is composed of both organics and nitrate containing species. This SOA formation can be linked to the dissolution of water soluble volatile organic compounds (VOCs) in the aqueous phase and to further aqueous phase reactions. Cloud-induced SOA formation is experimentally demonstrated in this study, thus highlighting the importance of aqueous multiphase systems in atmospheric SOA formation estimations. The authors thank Arnaud Allanic, Sylvain Ravier, Pascal Renard and Pascal Zapf for their contributions in the experiments. The authors also acknowledge the institutions that have provided financial support: the French National Institute for Geophysical Research (CNRS-INSU) within the LEFE-CHAT program through the project “Impact de la chimie des nuages sur la formation d’aérosols organiques secondaires dans l’atmosphère” and the French National Agency for Research (ANR) project CUMULUS ANR-2010-BLAN-617-01. This work was also supported by the EC within the I3 project “Integrating of European Simulation Chambers for Investigating Atmospheric Processes” (EUROCHAMP-2, contract no. 228335). The authors thank the MASSALYA instrumental platform (Aix Marseille Université, lce.univ-amu.fr) for the analysis and measurements used in this paper.This is the final version of the article. It first appeared from Copernicus Publications via http://dx.doi.org/10.5194/acp-16-1747-201

A new method to assess the acute toxicity toward honeybees of the abrasion particles generated from seeds coated with insecticides

Abstract Background: Large amounts of insecticide-containing dusts produced from abrasion of the seed dressing can be released into the atmosphere during sowing operations. Neonicotinoid pesticides, introduced in the 1990s for several crops, are the leading products for seed-coating treatments in many countries. Neonicotinoid containing dusts can be efectively intercepted by bees in fight over the sowing feld, inducing lethal acute efects, so that restrictions in the use of the main neonicotinoids have been adopted in the European Union. This led to the consequent introduction of replacement insecticides for seed-coating, i.e. methiocarb and thiacloprid, despite the lack of information on both the toxicity and the exposure scenarios for honeybees. Results: In this study, a laboratory apparatus was developed in order to quantify the toxicity of the dusts produced from the abrasion of the seed coating. This quantifcation is based on (i) an airstream transporting coating particles into an exposure chamber; (ii) exposure of bees to reproducible and measurable concentrations of insecticide, and (iii) direct measurement of the exposure dose on single bees. The method allowed us to perform in vivo experiments of honeybee exposure to provide toxicity data in more realistic exposure conditions. In fact, the formulation rather than the active principle alone can be tested, and the exposure is through dusts rather than a solution so that specifc absorption behavior can be studied in representative environmental conditions. The method was used to quantify the acute toxicity (LD50) of dusts obtained from the abrasion of corn seeds coated with clothianidin, thiacloprid and methiocarb. Conclusions: Our results show that, surprisingly, the replacement insecticide methiocarb has a toxicity (LD50=421– 693 ng/bee) in the same order of magnitude as clothianidin (LD50=113–451 ng/bee) through this specifc exposure route, while thiacloprid (LD50=16.9·103 ng/bee) has a signifcantly lower acute toxicity. Moreover, dusts containing methiocarb and clothianidin show a signifcant increase in toxicity when, after exposure, bees are kept under high humidity conditions. This suggests that the method here presented can be used to obtain complementary toxicity data in the risk assessment procedure for the authorization of new seed-coating insecticides or new formulations. Keywords: Systemic insecticides, Neonicotinoids, Methiocarb, Seed coating, Abrasion dusts, Honeybees, Pollinator insects, Acute toxicity, Exposure measuremen

Direct target and non-target analysis of urban aerosol sample extracts using atmospheric pressure photoionisation high-resolution mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous atmospheric pollutants of high concern for public health. In the atmosphere they undergo oxidation, mainly through reactions with center dot OH and NOx to produce nitro- and oxygenated (oxy-) derivatives. In this study, we developed a new method for the detection of particle-bound PAHs, nitro-PAHs and oxy-PAHs using direct infusion into an atmospheric pressure photoionisation high-resolution mass spectrometer (APPI-HRMS). Method optimisation was done by testing different source temperatures, gas flow rates, mobile phases and dopants. Samples were extracted with methanol, concentrated by evaporation and directly infused in the APPI source after adding toluene as dopant. Acquisition was performed in both polarity modes. The method was applied to target analysis of seasonal PM2.5 samples from an urban background site in Padua (Italy), in the Po Valley, in which a series of PAHs, nitro- and oxy-PAHs were detected. APPI-HRMS was then used for non-target analysis of seasonal PM2.5 samples and results compared with nano-electrospray ionisation (nanoESI) HRMS. The results showed that, when samples were characterised by highly oxidised organic compounds, including S-containing compounds, like in summer samples, APPI did not bring any additional information with respect to nanoESI in negative polarity (nanoESI(-)). Conversely, for winter samples, APPI(-) could detect a series of aromatic and poly-aromatic compounds, mainly oxidised and nitrogenated aromatics, that were not otherwise detected with nanoESI. (C) 2019 Elsevier Ltd. All rights reserved

Neonicotinoids thiamethoxam and clothianidin adversely affect the colonisation of invertebrate populations in aquatic microcosms

Surface waters are sometimes contaminated with neonicotinoids: a widespread, persistent, systemic class of insecticide with leaching potential. Previous ecotoxicological investigations of this chemical class in aquatic ecosystems have largely focused on the impacts of the neonicotinoid imidacloprid; few empirical, manipulative studies have investigated the effect on invertebrate abundances of two other neonicotinoids which are now more widely used: clothianidin and thiamethoxam. In this study, we employ a simple microcosm semi-field design, incorporating a one-off contamination event, to investigate the effect of these pesticides at field-realistic levels (ranging from 0 to 15 ppb) on invertebrate colonisation and survival in small ephemeral ponds. In line with previous research on neonicotinoid impacts on aquatic invertebrates, significant negative effects of both neonicotinoids were found. There were clear differences between the two chemicals, with thiamethoxam generally producing stronger negative effects than clothianidin. Populations of Chironomids (Diptera) and Ostracoda were negatively affected by both chemicals, while Culicidae appeared to be unaffected by clothianidin at the doses used. Our data demonstrate that field-realistic concentrations of neonicotinoids are likely to reduce populations of invertebrates found in ephemeral ponds, which may have knock on effects up the food chain. We highlight the importance of developing pesticide monitoring schemes for European surface waters

Metal ion release from fine particulate matter sampled in the Po Valley to an aqueous solution mimicking fog water: Kinetics and solubility

Metals are among the key aerosol components exerting adverse health effects. Their toxic properties may vary depending on their chemical form and solubility, which can be affected by aqueous processing during aerosol atmospheric lifetime. In this work, fine particulate matter (PM2.5) was collected in the city centre of Padua in the Po Valley (Italy), during a winter campaign. Part of the sampling filters were used to measure the kinetics by which metal ions and other elements can leach from PM2.5 to an aqueous solution mimicking fog water in the winter in temperate climate regions (pH 4.7, 5\ub0C). The leaching process was interpreted by a first order kinetics, and the fitting of the experimental data allowed to obtain the leaching kinetic constants and the equilibrium concentrations (i.e., at infinite time) for all elements. The remaining filter parts were mineralised, through two subsequent extraction steps, and the extracts were analysed by ICP-MS to gain the total elemental content of PM for a large number of elements. We found that elements can leach from PM with half times generally between 10\u201340 minutes, which is a timescale compatible with atmospheric aqueous processing during fog events. For instance, aluminium(III) in PM2.5 dissolved with an average k = 0.0185 min\u20131, and t1/2 = 37.5 min. Nevertheless, a fraction of each element was immediately solubilised after contact with the extraction solution suggesting that metal ion solubilisation may already had started during particle lifetime in the atmosphere