Australian Black summer smoke signal on Antarctic aerosol collected between New Zealand and the Ross sea.

Open biomass burning (BB) events are a well-known primary aerosol source, resulting in the emission of significant amount of gaseous and particulate matter and affecting Earth's radiation budget. The 2019-2020 summer, known as "Australian Black Summer", showed exceptional duration and intensity of seasonal wildfires, triggered by high temperatures and severe droughts. Since increasing megafires are predicted due to expected climate changes, it is critical to study the impact of BB aerosol on a large scale and evaluate related transport processes. In this study, five aerosol samples (total suspended particles with a diameter >1 µm) were collected during the XXXV Italian Expedition in Antarctica on board of the R/V Laura Bassi from 6th of January to February 16, 2020, along the sailing route from Lyttelton harbor (New Zealand) to Terra Nova Bay (Antarctica). Levoglucosan and its isomers have been analyzed as markers of BB, together with polycyclic aromatic hydrocarbons (PAHs), sucrose and alcohol sugars. Ionic species and carboxylic acids have been analyzed to support the identification of aerosol sources and its aging. Results showed high levoglucosan concentrations (325-1266 pg m-3) during the campaign, suggesting the widespread presence of smoke in the region, because of huge wildfire releases. Backward trajectories indicated the presence of long-range atmospheric transport from South America, probably carrying wildfires plume, in agreement with literature. Regional sources have been suggested for PAHs, particularly for 3-4 rings' compounds; monosaccharides, sucrose, arabitol, and mannitol were related to marine and biogenic contributions. In a warming climate scenario, more frequent and extensive wildfire episodes are expected in Australia, potentially altering albedo, aerosol radiative properties, and cloud interactions. Therefore, it is crucial to strengthens the investigations on the regional climatic effects of these events in Antarctica.

Uptake and translocation of brominated flame retardants in tomato plants (Solanum lycopersicum L.): Results from a standard soil-based biotest.

The uptake and translocation of four polybrominated diphenyl ethers (PBDEs) and four novel brominated flame retardants (NBFRs) in tomato plants (Solanum lycopersicum L.) were investigated via the RHIZOtest, a standard soil-based biotest, optimized for organic compounds. Tomato plants were exposed to soil samples spiked with 0 (i.e. control), 5.00 or 50.00 ng g-1dw of each compound. Compared of those of the control, exposure to increasing spiking concentrations resulted in average reductions of 13% and 26% (w/w) in tomato plant biomass. Higher concentrations of NBFRs were analyzed both in roots, ranging from 0.23 to 8.01 ng g-1dw for PBDEs and from 1.25 to 18.51 ng g-1dw for NBFRs, and in shoots, ranging from 0.09 to 5.58 ng g-1dw and from 0.47 to 7.78 ng g-1dw for PBDEs and NBFRs, respectively. This corresponded to an average soil uptake of 5% for PBDEs and 9% for NBFRs at the lower soil-spiking level, and 3% for PBDEs and 6% for NBFRs at the higher soil spiking level. Consequently, among both initial spiking levels, the soil-root concentration factor (RCF) values were lower on average for PBDEs (0.13 ± 0.05 g dw soil g-1dw roots) than for NBFRs (0.33 ± 0.16 g dw soil g-1dw roots). Conversely, nondifferent values of the root-shoot transfer factor (TF) were calculated for both PBDEs (0.54 ± 0.13 g dw roots g-1dw shoots) and NBFRs (0.49 ± 0.24 g dw roots g-1dw shoots). The differences and similarities reported in the RCF and TF between and within the two groups of compounds can be explained by their properties. The calculated RCF and TF values of the PBDEs exhibited a decreasing trend as the number of bromine atoms increased. Additionally, a robust negative linear correlation was observed between RCF values and the respective logKow values for the PBDEs, at both soil-spiking levels. The root uptake of NBFRs exhibited a negative correlation with their hydrophobicity; however, this was not observed in the context of root-to-shoot transfer. The presence of a second aromatic ring appears to be the key factor influencing the observed variations in NBFRs, with biphenyl NBFRs (BTBPE and DBDPE) characterized by lower uptake and reduced translocation potential than monophenyl PBEB and HBB. Understanding the transfer of these compounds to crops, especially near plastic recycling waste sites, is crucial for understanding the risks of their potential inclusion in the human food chain.

Fragrance materials affect life history parameters and gene expression in Daphnia magna: An emerging issue for freshwater ecosystems.

A chronic toxicity test (21 d exposure) with the model organism Daphnia magna was performed to study the single-compound and combined effects of four fragrance materials (FMs), including musk xylene (MX), Celestolide™ (ADBI), Galaxolide™ (HHCB), and ethylene brassylate (MT). Furthermore, the transcriptional responses of ten target genes related to detoxification, molting and reproduction (DHR96, P-gp, CYP360A8, GST, CYP314, EcRb, Vtg, CAT, GPX, and GCLC) were determined by performing a quantitative real-time polymerase chain reaction (qRT‒PCR) after juvenile D. magna was exposed for 48 h. The results showed that MX, ADBI and HHCB affected development and reproduction after chronic exposure at a concentration of 10 µg L-1. Conversely, MT did not affect reproduction, growth or molting during the 21 d exposure. In juvenile D. magna, gene expression was significantly altered by ADBI (DHR96, CYP260A8, and GCLC) and MX (DHR96, CYP360A8, EcRb, Vtg, CYP314, and GCLC) but not by HHCB. These results suggest that compared to biochemical measures, conventional biological endpoints provide more informative data regarding the effects of this FM. Compared to single substances in the chronic test, the mixture of the four FMs showed effects at lower concentrations and increased gene expression for EcRb and CYP314 during juvenile exposure, indicating a possible additive or synergistic effect of the four FMs compared to single compound exposure.

Dataset of analyzes performed to determine the level and timing of selected organic pollutants' inputs in sediments of the Lake of Cavazzo (Italy).

This data article presents the dataset collected for selected organic pollutants in the framework of a larger research project aimed at assessing the effects of different environmental stressors (natural and anthropogenic) in sediments of the Lake of Cavazzo, a basin of glacial origin located in a seismically active region of the Italian Eastern Alps. Information relative to sampling strategy and operations, location of sampling sites, sedimentary chronological benchmarks, and profiles of RGB (Red-Green-Blue) color code determined from high resolution photos taken at cores CAV-04 and CAV-06 are reported, together with analytical data for 15 polycyclic aromatic hydrocarbons, 21 polychlorinated biphenyls' congeners (including the non-Aroclor CB-11), 14 polybrominated diphenyl ethers' congeners, and 22 organochlorine pesticides, whose concentrations were determined by Gas Chromatography coupled both to Low-Resolution and High-Resolution Mass Spectrometry. Interpretation of this dataset is fully discussed in the companion article by Pizzini et al. (2022) and relys on the multi-proxy analysis of sediment samples presented in Polonia et al. (2021) that highlighted lake stratigraphy and major changes occurring at a decadal scale since the 1950s.

PAHs, PCBs, PBDEs, and OCPs trapped and remobilized in the Lake of Cavazzo (NE Italy) sediments: Temporal trends, quality, and sources in an area prone to anthropogenic and natural stressors.

Under the present climatic emergency, the environmental quality of freshwater reservoirs is an increasingly urgent topic as its deterioration threatens humans and ecosystems. It is evident that pollution by natural and anthropogenic contaminants must be avoided or reduced. The Lake of Cavazzo (NE Italy) is a natural perialpine basin which, from the mid-20th century, has sustained several anthropogenic impacts that added to the effects of the intense regional seismicity. Starting from 2015, in response to concerns raised by local authorities, a multidisciplinary investigation of the lake floor and sub-floor was conducted, including a geophysical survey and the collection of sediment cores. Two of them were studied to detect contamination by Polycyclic Aromatic Hydrocarbons (PAHs) and specific Persistent Organic Pollutants (POPs; i.e. PolyChlorinated Biphenyls - PCBs, PolyBrominated Diphenyl Ethers - PBDEs, and OrganoChlorine Pesticides - OCPs), and to verify the link with known anthropogenic stressors. Results were interpreted in light of previous studies suggesting modified conditions after the '50s, and recognized the effects of the 1976-1977 MW 6.5 seismic sequence in resuspending sediments within the basin. Analyzed pollutants defined a potential critical situation only for few OCPs, above all 2,4'- and 4,4'-DDT isomers. In addition, PBDEs were found at concentrations exceeding those of other heavily polluted alpine lakes. Mass movements (either seismic or human induced) have likely resuspended and transferred pollutants from shallower locations to the lake depocenter, showing the potential of re-exposing contaminated layers to biomagnification processes along the lacustrine food chain. Local inputs of pollutants prevail over distributed sources, suggesting a link with local agricultural or industrial activities. Indeed, works connected to the construction of the hydroelectric power plant in the '50s might have reworked local sediments perturbing their natural accretion. Results of this work might inspire similar studies in other problematic lacustrine areas that sustain both natural and anthropogenic stressors.

Detection of glyphosate residues in feed, saliva, urine and faeces from a cattle farm: a pilot study.

Forty-two samples of feed, saliva, urines, and faeces collected from a cattle farm were investigated with the aim to evaluate the occurrence of glyphosate in faeces, urine and saliva. Glyphosate in the feed was also quantified to understand how it was assimilated by mammals. All cows excreted glyphosate in their faeces at concentrations between 57 and 983 ng g-1. In contrast, only 55% of urine and one sample of saliva tested positive. Most of the feeds demonstrated a non-negligible presence of glyphosate. In particular, a silage containing soybeans from genetically modified cultivation showed a concentration one order of magnitude higher than the other feeds. This study aims to provide the first complete determination of glyphosate in a cattle farm, considering the possible re-entry into the environment through the spreading of liquid and solid sewage and its possible impact on groundwater.

Assessing glyphosate in water, marine particulate matter, and sediments in the Lagoon of Venice.

Lagoon water, suspended particulate matter, and sediment samples from seven sites at Lagoon of Venice were collected from 2019 to 2021 in order to study the presence of the herbicide glyphosate (N-(phosphonomethyl)glycine), among the most widely used agricultural chemicals worldwide, but its occurrence in lagoon water environment has not been deeply investigated. The sites were selected considering a supposed diversity of inputs and of pollution levels. An analytical method based on ion chromatography coupled with tandem mass spectrometry was optimized and validated for lagoon water, marine particulate matter, and sediment samples. Maximum concentrations of glyphosate were 260 and 7 ng L-1 for lagoon water and suspended particulate matter, respectively, and 15 ng g-1 for sediment, with some spatial and temporal fluctuations. Our results demonstrate that glyphosate content in the Venice Lagoon mainly depends on external forcing from river inlets and agricultural lagoon activities.

Maize plant (Zea mays) uptake of organophosphorus and novel brominated flame retardants from hydroponic cultures.

The root uptake and root-shoot translocation of seven organophosphorus flame retardants (OPFRs) and four novel brominated flame retardants (NBFRs) were assessed in this investigation using hydroponic grown maize plants (Zea mays). Three initial liquid concentrations for each considered compound were examined (i.e., 0.3 µg L-1, 3 µg L-1, 30 µg L-1). The results indicated that the 30 µg L-1 treatments were phytotoxic, as they resulted in a significant decrease in shoot dry weight. Plant-driven removal of the tested FRs decreased with the increasing initial spiking level and were reportedly higher for the NBFRs (range 42%-10%) than OPFRs (range 19%-7%). All the considered FRs were measured in the roots (range 0.020-6.123 µg g-1 dry weight -DW-) and shoots (range 0.012-1.364 µg g-1 DW) of the tested plants, confirming that there was uptake. Linear relationships were identified between the chemical concentrations in the plant parts and the tested hydroponic concentrations. Root concentration factors were positively correlated with the specific lipophilicity (i.e., logKow) of the tested FRs and were determined to be higher for the NBFRs than the OPFRs. The NBFRs had a higher root uptake rate than the OPFRs, and this trend was more significant with the increasing treatment concentrations. Shoot/root concentration factors were found to be lower than the unity value for 10 of the 11 tested compounds. These results can be related to the specific molecular configurations and the occurrence of different functional groups in the tested compounds. The results will help to improve risk assessment procedures and fine tune our understanding of human receptor responses to the ingestion of maize crops grown on agricultural sites irrigated with water contaminated by FRs.

Organic pollutants in protected plain areas: The occurrence of PAHs, musks, UV-filters, flame retardants and hydrocarbons in woodland soils.

Protected woodlands are rare and small portions of the plain territory of northern Italy, where agricultural, industrial and urban activities strongly dominate the landscape. Such natural areas are frequently set on river floodplains and are therefore potentially conditioned by the contamination brought by the surface waters. We investigated the occurrence of multiple categories of organic pollutants, including Polycyclic Aromatic Hydrocarbons (PAHs), Musk fragrances, UV-filters, organophosphorus and novel brominated Flame Retardants (FRs) and Total Petroleum Hydrocarbons (TPH) in woodland soils of eight different protected areas. The samples collected in the floodplains of the Po, Adige and Fratta rivers resulted more contaminated, with levels of PAHs up to 633 ng g-1. Moreover, these samples for the first time revealed the presence of personal care products, primarily 2-ethylhexyl-4-methoxycinnamate (EHMC) and tonalide (AHTN), in soils of protected woodlands, reaching respectively 3.4 ng g-1 and 5.0 ng g-1, together with the occurrence of both organophosphorus and brominated FRs, with total concentrations up to 15 ng g-1. Higher concentrations of hydrocarbons, with TPH in the range 5-65 µg g-1, were instead reflecting the inputs of long chain n-alkanes from epicuticular waxes more than petrogenic contamination.

Occurrence and source apportionment of organic pollutants in deep sediment cores of the Venice Lagoon.

In this study, recent and aged inputs of five classes of organic contaminants (i.e. PCBs, OCPs, PCDD/Fs, PAHs, and n-Alkanes) were evaluated in eight deep sediment cores of the Venice Lagoon, collected along the path of a new waterway whose excavation is under evaluation by local authorities, to assess the environmental quality status of the area. Diagnostic indices were calculated for identifying pollutant distribution patterns and their major emission sources, whose relative contribution was quantified by a Positive Matrix Factorization source apportionment model. Sedimentary depth profiles highlighted higher contamination in the top layer, mainly related to ship traffic combustion and vehicular/industrial emissions from the mainland. Nevertheless, a significant level of pollution has been detected also in the deeper layers, probably due to the transport of particulate matter through the aquifers underlying the lagoon seabed. The results underlined the threat posed by the possible resuspension of pollutants in the water column during contaminated sediment dredging.

Dataset for the assessment of selected POP's pollution and effectiveness of environmental policies in the Bac Giang Province and Cau River (Northern Vietnam).

This data article presents the datasets obtained during the years 2011-2012 in the Provinces of Bac Giang and Bac Ninh (Northern Vietnam) in the framework of an International Cooperation project aimed at the restoration and preservation of natural resources together with the improvement of life conditions of the local population. All information relative to sampling strategy, location and description of the studied sites are reported, together with analytical data (i.e. grain size, Total Organic Carbon, Organic Nitrogen, C/N ratio, δ13C, PolyChlorinated Biphenyls, Polycyclic Aromatic Hydrocarbons, PolyBrominated Diphenyls Ethers, PolyChlorinated Dibenzo-p-Dioxins and Furans, OrganoChlorine Pesticides, Total Petroleum Hydrocarbons). In addition, maximum admitted levels, quality standards and emission limits set by the Vietnamese environmental regulations are reported in comparison to Italian ones for the following parameters and environmental compartments: noise, soils, air, drinking and groundwaters, sediments. Interpretation of this dataset is fully discussed in Giuliani et al. (2019) [1].

Fragrances and PAHs in snow and seawater of Ny-Ålesund (Svalbard): Local and long-range contamination.

Polar regions are fragile ecosystems threatened by both long-range pollution and local human contamination. In this context, the environmental distribution of the Personal Care Products (PCPs) represent a major knowledge gap. Following preliminary Antarctic studies, Fragrance Materials (FMs) were analyzed in the seawater and snow collected in the area of Ny-Ålesund, Svalbard, to investigate local and long-range contamination. Polycyclic Aromatic Hydrocarbons (PAHs), including Retene, were determined in parallel to help the identification of the governing processes. Concentrations of FMs up to 72 ng L-1 were detected in the surface snow near the settlement and at increasing distances, in relation to the prevailing winds. PAHs follow a similar scheme, with levels of Retene up to 1.8 µg L-1, likely deriving from the occurrence of this compound in the coal dust due to the previous mining activities in the area. The snow seasonal deposition of FMs and PAHs was estimated in a snowpit dug at the top of the Austre Brøggerbreen glacier, indicating the long-range atmospheric transport (LRAT) of these compounds.

Distribution of fragrances and PAHs in the surface seawater of the Sicily Channel, Central Mediterranean.

The Mediterranean Sea is highly influenced by several anthropic pressures, including different kinds of organic pollutants. Fragrance Materials (FMs) and Polycyclic Aromatic Hydrocarbons (PAHs) were investigated in the surface seawater of the Sicily Channel in offshore and coastal areas. Total concentrations of FMs and PAHs resulted respectively up to 112ngL-1 and 43ngL-1, with similar distributions of both classes of analytes. Low values were detected in some coastal samples, due to the upwelling of deep and unpolluted waters, while the presence of gyres probably accumulates contaminants in offshore areas. Confirming previous works, the allergenic and oestrogenic Salicylates generally resulted the most abundant FMs and diagnostic ratios indicated combustion processes as the sources of PAHs. The coupling of the well-known PAHs with a new class of Personal Care Products (PCPs) helped the identification of the major environmental drivers: the results highlighted the role of mesoscale hydrodynamics and suggested long-range atmospheric transport as key factors. The first detection of the selected FMs in open sea areas supports the hypothesis of their environmental persistence.

Fragrances in the seawater of Terra Nova Bay, Antarctica.

Personal Care Products are emerging pollutants whose distribution in the Antarctic and remote environments is still largely unknown. Among PCPs, long-lasting and stable Fragrance Materials were selected to perform a first pilot study on their occurrence in the coastal surface seawater of Terra Nova Bay in the Ross Sea, Antarctica. Ambrofix, Amyl Salicylate, Benzyl Salicylate, Hexyl Salicylate, Lemonile and Okoumal were detected for the first time in Antarctic natural seawater, and reached total concentrations up to 100ngL-1. Treated discharges from the Italian research station Mario Zucchelli (MZS) contain FMs, however concentrations in nearby Tethys Bay increase during the seasonal melt of the sea ice and its snow cover: variability in emissions and distribution, as well as a contribution from atmospheric (long or short-range) transport were hypothesized.

3,3'-dichlorobiphenyl (non-Aroclor PCB-11) as a marker of non-legacy PCB contamination in marine species: comparison between Antarctic and Mediterranean bivalves.

In this study the accumulation of the 3,3'-dichlorobiphenyl (PCB-11) in monitoring organisms from the Antarctic and Mediterranean coastal environments has been investigated. This lesser-known PCB congener, unrelated to the industrial use of commercial mixtures, continues to be generated and released into the environment mainly as an unintentional by-product of pigment manufacturing. Specimens of the filter-feeders Adamussium colbecki from Terra Nova Bay and of Mytilus galloprovincialis and Ruditapes philippinarum from the north-western Adriatic coasts were collected and analyzed for PCB-11 by Gas Chromatography coupled both to Low-Resolution and High-Resolution Mass Spectrometry (LRMS, HRMS). In order to assess the influence of PCB-11 with respect to the legacy contamination, 126 PCB congeners related to the Aroclor commercial mixtures were simultaneously analyzed. PCB-11 was detected in all the samples, regardless of the species and of the geographical area, representing on average 17.6% and 15.6% of the total PCBs (n = 127) in Antarctic and Mediterranean samples, respectively. In the Adriatic area the highest concentrations were related to the influence of industrial activities or ship traffic, while the highest value found in Antarctic specimens, namely those collected in the austral summer 1997-1998, was ascribed to a local anthropogenic source. The occurrence of PCB-11 in the other samples from Terra Nova Bay may be related to Long-Range Atmospheric Transport (LRAT), facilitated by the higher volatility of the analyte compared to the heavier PCB congeners. Nevertheless, more in-depth studies are needed in order to evaluate the relative contribution of local and distant sources.

Retrospective biomonitoring of chemical contamination in the marine coastal environment of Terra Nova Bay (Ross Sea, Antarctica) by environmental specimen banking.

Antarctica offers a good opportunity to investigate planetary-scale pollution and climate change, and provides baseline values for contaminants such as Trace Elements (TEs) and Persistent Organic Pollutants (POPs). Literature data on contaminant levels in the Antarctic environment indicate that long-range atmospheric transport is the primary pathway by which pollutants from surrounding continents are carried to this pristine environment. However, local contamination sources represented by the scientific stations are also not negligible. Climate change and global warming are altering the global budget of anthropogenic contaminants and their monitoring in Antarctica ecosystems is very important to protect the global environment. In this work, eighty specimens of Adamussium colbecki (Smith, 1902), a benthic Antarctic scallop, collected from 1996 to 2009 and stored in the Antarctic Environmental Specimen Bank, were analyzed to quantify TEs and POPs, including polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and polycyclic aromatic hydrocarbons (PAHs). Metals concentrations were not affected by anthropogenic contributions, highlighting a natural accumulation with the age of the organism. Similarly, no temporal trend was found for PCNs, PCBs and PAHs. However, specimens collected during the summer 1997-98 showed enhanced concentration levels of PCBs and PAHs that could refer to a local anthropogenic source of contamination.

Simultaneous determination of halogenated contaminants and polycyclic aromatic hydrocarbons: a multi-analyte method applied to filter-feeding edible organisms.

This study develops and validates a novel analytical approach for the simultaneous determination of 127 polychlorinated biphenyls (PCBs), together with 6 polychlorinated naphthalenes (PCNs) and 16 polycyclic aromatic hydrocarbons (PAHs). PCBs, PCNs, and PAHs were subjected to a unique pretreatment protocol and were simultaneously determined in a single chromatographic run, using GC-MS, in environmental marine samples of mussels and clams. The results of the validation experiments, which were performed on the standard reference materials (NIST SRM 1974C - slurried matrix and NIST SRM 2977 - freeze-dried matrix), were in accordance with the certified and the reference values. The repeatability of the method for all target compounds, expressed as mean relative standard deviations, ranged from 2.5 to 5.1 % for PCBs, from 3.9 to 5.5 % for PCNs, and from 8.6 to 17.9 % for PAHs; the first value of each pair refers to the freeze-dried matrix and the second to the fresh one, for each of the classes of compounds examined. The quantification limits were in the range of 0.2-6 pg for PCBs, 0.4-8 pg for PCNs, and 0.2-15 pg for PAHs (on column). The method recoveries yielded good results (62 ± 19 % for the freeze-dried matrix and 60 ± 14 % for the fresh one) and were not significantly reduced by adopting a single analytical protocol compared with the use of different group-specific analytical methods. No serious interferences were encountered and good selectivity was achieved. These results show that this method allows one to increase the laboratory sample throughput while requiring a small amount of tissue and saving time. Graphical Abstract Simultaneous determination of halogenated contaminants and polycyclic aromatic hydrocarbons: a multianalyte method applied to filter-feeding edible organisms.

Can PBDE natural formation and degradation processes interfere with the identification of anthropogenic trends and sources? Evidences from sediments of the Nador Lagoon (Morocco).

This paper presents the first results related to PBDE concentrations in sediments of the Nador Lagoon (N-E Morocco), an area endangered by different pollutant sources. Analyses were performed by HRGC-LRMS and confirmed by HRGC-HRMS on selected samples. Total surficial concentrations were 0.059-8.2ngg(-1). The maxima were found close to Nador City. Along the sedimentary records, the highest total concentrations (11 and 2.2ngg(-1)) were found at depths corresponding to times (1930s-1950s) when these chemicals were not yet produced. Dehydroxylation or demethoxylation of naturally occurring structural analogues of PBDEs under reducing conditions was suggested. BDE-47 dominated the congener compositions, while BDE-209, when present, could be detected only by HRGC-HRMS, proving that analytical degradation modified the original assemblage. Microbial anaerobic degradation could have changed congener compositions in sediments deposited from the 1970s to the 2000s. Current values are not harmful, but increasing trends call for constant monitoring.

Direct immersion solid-phase microextraction with gas chromatography and mass spectrometry for the determination of specific biomarkers of human sweat in melted snow.

To provide a reliable tool for investigating diffusion processes of the specific components of the human odor 3-hydroxy-3-methylhexanoic acid and 3-methyl-3-sulfanylhexan-1-ol through the snowpack, we developed and optimized an analytical method based on direct immersion solid-phase microextraction followed by gas chromatography with mass spectrometry. Direct immersion solid-phase microextraction was performed using polyacrylate fibers placed in aqueous solutions containing 3-hydroxy-3-methylhexanoic acid and 3-methyl-3-sulfanylhexan-1-ol. After optimization, absorption times of 120 min provided a good balance to shorten the analysis time and to obtain suitable amounts of extractable analytes. The extraction efficiency was improved by increasing the ionic strength of the solution. Although the absolute extraction efficiency ranged between 10 and 12% for 3-hydroxy-3-methylhexanoic acid and 2-3% for 3-methyl-3-sulfanylhexan-1-ol, this method was suitable for analyzing 3-hydroxy-3-methylhexanoic acid and 3-methyl-3-sulfanylhexan-1-ol concentrations of at least 0.04 and 0.20 ng/mL, respectively. The precision of the direct immersion solid-phase microextraction method ranged between 8 and 16%. The variability within a batch of six fibers was 10-18%. The accuracy of the method provided values of 88-95 and 86-101% for 3-hydroxy-3-methylhexanoic acid and 3-methyl-3-sulfanylhexan-1-ol, respectively. The limit of detection (and quantification) was 0.01 ng/mL (0.04 ng/mL) for 3-hydroxy-3-methylhexanoic acid and 0.06 ng/mL (0.20 ng/mL) for 3-methyl-3-sulfanylhexan-1-ol. The signal versus concentration was linear for both compounds (r(2) = 0.973-0.979). The stability of these two compounds showed that 3-hydroxy-3-methylhexanoic acid was more stable in water than 3-methyl-3-sulfanylhexan-1-ol. We applied the method to environmental samples in correspondence with an olfactory target buried previously.

GC-MS method for determining faecal sterols as biomarkers of human and pastoral animal presence in freshwater sediments.

In order to determine sterols and stanols in freshwater sediments to reconstruct the past presence of humans and pastoral animals, we developed an analytical method based on pressurised liquid extraction (PLE), clean-up performed using solid phase extraction (SPE) and sterol determination using gas chromatography-mass spectrometry (GC-MS) analysis. PLE extraction conditions were optimised using dichloromethane (DCM) and DCM/methanol mixtures. Clean-up was performed with 2 g silica SPE cartridges, and the concentrated extracts were eluted with 70 mL DCM. Extraction yield was evaluated using an in-house reference material spiked with (13)C-labelled cholesterol and aged for 10 days. In comparison with pre-extraction, where the sediment is extracted and then spiked with a known analyte concentration, this approach preserves the original composition of the sediment. DCM and DCM/methanol mixtures resulted in high extraction yields ranging from 86 to 92 % with good reproducibility (relative standard deviation (RSD) 5-8 %). PLE extraction yields obtained with DCM as the extracting solvent were about 1.5 times higher than extractions using an ultrasonic bath. The solvent extraction mixture and matrix composition strongly affected the solvent extraction composition where higher overall recoveries (70-80 %) for each compound were obtained with DCM. The extraction mixture and matrix composition also affected the analyte concentrations, resulting in a method precision ranging from 1 to 18 %. Diatomaceous earth spiked with 10 to 100 ng of sterols, and environmental samples fortified with suitable amounts of sterols provided apparent recovery values ranging from 90 to 110 %. We applied the method to environmental samples both close to and upstream from sewage discharge zones, resulting in substantially higher faecal sterol (FeSt) concentrations near the sewage. In addition, we also applied the method to a 37-cm freshwater sediment core in order to evaluate its applicability for obtaining vertical sterol profiles.