Organ-specific mercury stable isotopes, speciation and particle measurements reveal methylmercury detoxification processes in Atlantic Bluefin Tuna.

Identifying metabolism and detoxification mechanisms of Hg in biota has important implications for biomonitoring, ecotoxicology, and food safety. Compared to marine mammals and waterbirds, detoxification of MeHg in fish is understudied. Here, we investigated Hg detoxification in Atlantic bluefin tuna Thunnus thynnus using organ-specific Hg and Se speciation data, stable Hg isotope signatures, and Hg and Se particle measurements in multiple tissues. Our results provide evidence for in vivo demethylation and biomineralization of HgSe particles, particularly in spleen and kidney. We observed a maximum range of 1.83‰ for δ202Hg between spleen and lean muscle, whereas Δ199Hg values were similar across all tissues. Mean percent methylmercury ranged from 8% in spleen to 90% in lean muscle. The particulate masses of Hg and Se were higher in spleen and kidney (Hg: 61% and 59%, Se: 12% and 6%, respectively) compared to muscle (Hg: 2%, Se: 0.05%). Our data supports the hypothesis of an organ-specific, two-step detoxification of methylmercury in wild marine fish, consisting of demethylation and biomineralization, like reported for waterbirds. While mass dependent fractionation signatures were highly organ specific, stable mass independent fractionation signatures across all tissues make them potential candidates for source apportionment studies of Hg using ABFT.

Precise measurement of Fe isotopes in marine and biological samples by pseudo-high-resolution multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS).

This paper introduces an enhanced technique for analyzing iron isotopes in complex marine and biological samples. A dedicated iron purification method for biological marine matrices, utilizing three ion exchange columns, is validated. The MC-ICPMS in pseudo-high-resolution mode determines precise iron isotopic ratios, with sensitivity improved through the DSN-100 desolvating nebulizer system and Apex-IR. Only 2 µg of iron on DSN versus 1 µg on Apex is needed for six replicates (30-60 times improvement) while 10 to 20 µg is required for a single measurement on a wet system considering the resolution power (Rp) is maintained at 11,000-13,000. The Ni-doping method with a Fe/Ni ratio of 1 yields more accurate isotopic ratios than standard-sample bracketing alone. Measurement reproducibility of triplicate samples from marine biological experiments on MC-ICPMS is ± 0.03‰ (2SD) for δ56Fe and ± 0.07‰ for δ57Fe (2SD). This study introduces a novel iron purification process specifically designed for marine and biological samples, enhancing sensitivity and enabling more reliable measurements with smaller sample sizes and reduced uncertainties. It proposes iron isotopic compositions for biological reference materials, offering a valuable reference dataset in diverse scientific disciplines.

Authenticating teas using multielement signatures, strontium isotope ratios, and volatile compound profiling.

High value food products are subject to adulterations and frauds. This study aimed to combine, in our knowledge for the first time, inorganic chemical tracers (multi-elements and Sr isotopy) with volatile organic compound (VOCs) to discriminate the geographic origin, the varieties and transformation processes to authenticate 26 tea samples. By measuring Sr isotope ratio using the multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), 6 out of 11 regions were successfully discriminated. The combination with the ICP-MS inorganic pattern allowed to discriminate 4 more regions with a significance level of 0.05. VOCs fingerprints, obtained with selected ion flow tube mass spectrometer (SIFT-MS), were not correlated with origin but with the cultivar and transformation processes. Green, oolong, and dark teas were clearly differentiated, with hexanal and hexanol contributing to the discrimination of oxidation levels. With this multi-instrumental approach, it is possible to certify the geographical origin and the tea conformity.

Reply to the comment on "New insights into the biomineralization of mercury selenide nanoparticles through stable isotope analysis in giant petrel tissues" by A. Manceau, J. Hazard. Mater. 425 (2021) 127922. doi: 10.1016/j.jhazmat.2021.127922.

In the comments reported by A. Manceau [1], relating to our recent paper on mercury (Hg) species-specific isotopic characterization in giant petrel tissues [2] two critical questions were raised. Firstly, according to A. Manceau, our method of extraction and isolation of nanoparticles was not able to efficiently isolate mercury selenide nanoparticles (HgSe NPs) and therefore the δ202Hg values measured are not species-specific, but rather δ202Hg of mixtures of complexes such as MeHgCys, Hg(Sec)4, and HgSe. Secondly, he suggests that our main findings showing that no isotopic fractionation is induced during the HgSe NPs biomineralization step from the precursor-demethylated species is erroneous because it contradicts the conclusion of two recent articles by A. Manceau and co-workers [3,4]. In this reply we defend our scientific findings and respectively respond to the questions and comments raised by A. Manceau.

New insights into the biomineralization of mercury selenide nanoparticles through stable isotope analysis in giant petrel tissues.

Tiemannite (HgSe) is considered the end-product of methylmercury (MeHg) demethylation in vertebrates. The biomineralization of HgSe nanoparticles (NPs) is understood to be an efficient MeHg detoxification mechanism; however, the process has not yet been fully elucidated. In order to contribute to the understanding of complex Hg metabolism and HgSe NPs formation, the Hg isotopic signatures of 40 samples of 11 giant petrels were measured. This seabird species is one of the largest avian scavengers in the Southern Ocean, highly exposed to MeHg through their diet, reaching Hg concentrations in the liver up to more than 900 µg g-1. This work constitutes the first species-specific isotopic measurement (δ202Hg, Δ199Hg) of HgSe NPs in seabirds and the largest characterization of this compound in biota. Similar δ202Hg values specifically associated to HgSe (δ202HgHgSe) and tissues (δ202Hgbulk) dominated by inorganic Hg species were found, suggesting that no isotopic fractionation is induced during the biomineralization step from the precursor (demethylated) species. In contrast, the largest variations between δ202Hgbulk and δ202HgHgSe were observed in muscle and brain tissues. This could be attributed to the higher fraction of Hg present as MeHg in these tissues. Hg-biomolecules screening highlights the importance of the isotopic characterization of these (unknown) complexes.

Analytical strategies for Sr and Pb isotopic signatures by MC-ICP-MS applied to the authentication of Champagne and other sparkling wines.

Wine is one of the most counterfeit product and therefore, requires certifying of its origin and provenance. For authentication purposes, analytical strategies for the determination of Sr and Pb isotopic ratios were adapted for Champagne and sparkling wines. All analytical steps have been carefully adapted and optimized regarding sample preparation, mineralization, and purification by resins as well as isotopic composition measurements on 3 different MC ICP-MS instruments. Further, a global approach using an "in-house" reference material of Champagne (ChRM) was realized and used throughout as well as routine analytical conditions to guaranty samples isotopic quality determination over 3 years. These developments allowed to select the best conditions at all steps for reaching the best precision and accuracy to be used under routine conditions for samples origin discrimination. The best condition of mineralization was obtained with a hot block system allowing both efficiency in digestion and high sample throughput. Detailed conditions of purification for both Sr and Pb isotopes were also optimized and discussed. These different optimization steps on the whole analytical chain allowed to estimate a global precision suitable to be used routinely to discriminate the origin of different Champagne samples. For Sr isotopic analysis (87Sr/86Sr), the overall external precision based on preparation replicates of ChRM was 2σ = 0.000024 (n = 36) and for the Pb isotopes analysis (208Pb/206Pb), the precision obtained on ChRM was 2σ = 0.0024 (n = 15). Finally, we have applied these developments by combining both Sr and Pb isotopic ratios in order to discriminate the origin of sparkling wines from around the world. The combined isotopic signature, using both Sr and Pb isotopes ratios, permitted a clear discrimination between certified Champagne wines and other European and Non-European sparkling wines.

Specificity and Origin of the Stability of the Sr Isotopic Ratio in Champagne Wines.

The 87Sr/86Sr ratio of 39 Champagnes from six different brands, originating from the whole "Appellation d'Origine Contrôlée" (AOC) Champagne was analyzed to establish a possible relation with the geographical origin. Musts (i.e., grape juice) and base wines were also analyzed to study the evolution of the Sr isotopic ratio during the elaboration process of sparkling wine. The results demonstrate that there is a very homogeneous Sr isotopic ratio (87Sr/86Sr = 0.70812, n = 37) and a narrow span of variability (2σ = 0.00007, n = 37). Moreover, the Sr concentrations in Champagnes have also low variability, which can be in part explained by the homogeneity of the bedrock in the AOC Champagne. Measurements of the 87Sr/86Sr ratio from musts and base wines show that blending during Champagne production plays a major role in the limited variability observed. Further, the 87Sr/86Sr of the musts were closely linked to the 87Sr/86Sr ratio of the vineyard soil. It appears that the 87Sr/86Sr of the product does not change during the elaboration process, but its variability decreases throughout the process due to blending. Both the homogeneity of the soil composition in the Champagne AOC and the blending process during the wine making process with several blending steps at different stages account for the unique and stable Sr isotopic signature of the Champagne wines.

Hg isotopic composition of one-year-old spruce shoots: Application to long-term Hg atmospheric monitoring in Germany.

The Hg isotopic composition of 1-year-old Norway spruce (Picea abies) shoots collected from Saarland cornurbation Warndt, Germany, since 1985 by the German Environmental Specimen Bank, were measured for a better understanding of the temporal trends of Hg sources. The isotopic data showed that Hg was mainly taken up as gaseous element mercury (GEM) and underwent oxidation in the spruce needles; this led to a significant decrease in the δ202Hg compared with the atmospheric Hg isotopic composition observed for deciduous leaves and epiphytic lichens. Observation of the odd mass-independent isotopic fractionation (MIF) indicated that Δ199Hg and Δ201Hg were close to but slightly lower than the actual values recorded from the atmospheric measurement of the GEM isotopic composition in non-contaminated sites in U.S. and Europe, whereas observation of the even-MIF indicated almost no differences for Δ200Hg. This confirmed that GEM is a major source of Hg accumulation in spruce shoots. Interestingly, the Hg isotopic composition in the spruce shoots did not change very significantly during the study period of >30 years, even as the Hg concentration decreased significantly. Even-MIF (Δ200Hg) and mass-dependent fractionation (MDF) (δ202Hg) of the Hg isotopes exhibited slight decrease with time, whereas odd-MIF did not show any clear trend. These results suggest a close link between the long-term evolution of GEM isotopic composition in the air and the isotopic composition of bioaccumulated Hg altered by mass-dependent fraction in the spruce shoots.

Contamination levels and habitat use influence Hg accumulation and stable isotope ratios in the European seabass Dicentrarchus labrax.

Hg accumulation in marine organisms depends strongly on in situ water or sediment biogeochemistry and levels of Hg pollution. To predict the rates of Hg exposure in human communities, it is important to understand Hg assimilation and processing within commercially harvested marine fish, like the European seabass Dicentrarchus labrax. Previously, values of Δ199Hg and δ202Hg in muscle tissue successfully discriminated between seven populations of European seabass. In the present study, a multi-tissue approach was developed to assess the underlying processes behind such discrimination. We determined total Hg content (THg), the proportion of monomethyl-Hg (%MeHg), and Hg isotopic composition (e.g. Δ199Hg and δ202Hg) in seabass liver. We compared this to the previously published data on muscle tissue and local anthropogenic Hg inputs. The first important finding of this study showed an increase of both %MeHg and δ202Hg values in muscle compared to liver in all populations, suggesting the occurrence of internal MeHg demethylation in seabass. This is the first evidence of such a process occurring in this species. Values for mass-dependent (MDF, δ202Hg) and mass-independent (MIF, Δ199Hg) isotopic fractionation in liver and muscle accorded with data observed in estuarine fish (MDF, 0-1‰ and MIF, 0-0.7‰). Black Sea seabass stood out from other regions, presenting higher MIF values (≈1.5‰) in muscle and very low MDF (≈-1‰) in liver. This second finding suggests that under low Hg bioaccumulation, Hg isotopic composition may allow the detection of a shift in the habitat use of juvenile fish, such as for first-year Black Sea seabass. Our study supports the multi-tissue approach as a valid tool for refining the analysis of Hg sourcing and metabolism in a marine fish. The study's major outcome indicates that Hg levels of pollution and fish foraging location are the main factors influencing Hg species accumulation and isotopic fractionation in the organisms.

Contrasting Spatial and Seasonal Trends of Methylmercury Exposure Pathways of Arctic Seabirds: Combination of Large-Scale Tracking and Stable Isotopic Approaches.

Despite the limited direct anthropogenic mercury (Hg) inputs in the circumpolar Arctic, elevated concentrations of methylmercury (MeHg) are accumulated in Arctic marine biota. However, the MeHg production and bioaccumulation pathways in these ecosystems have not been completely unraveled. We measured Hg concentrations and stable isotope ratios of Hg, carbon, and nitrogen in the feathers and blood of geolocator-tracked little auk Alle alle from five Arctic breeding colonies. The wide-range spatial mobility and tissue-specific Hg integration times of this planktivorous seabird allowed the exploration of their spatial (wintering quarters/breeding grounds) and seasonal (nonbreeding/breeding periods) MeHg exposures. An east-to-west increase of head feather Hg concentrations (1.74-3.48 µg·g-1) was accompanied by significant spatial trends of Hg isotope (particularly Δ199Hg: 0.96-1.13‰) and carbon isotope (δ13C: -20.6 to -19.4‰) ratios. These trends suggest a distinct mixing/proportion of MeHg sources between western North Atlantic and eastern Arctic regions. Higher Δ199Hg values (+0.4‰) in northern colonies indicate an accumulation of more photochemically impacted MeHg, supporting shallow MeHg production and bioaccumulation in high Arctic waters. The combination of seabird tissue isotopic analysis and spatial tracking helps in tracing the MeHg sources at various spatio-temporal scales.

Hg isotopic composition and total Hg mass fraction in NIES Certified Reference Material No. 28 Urban Aerosols.

An interlaboratory study on the National Institute for Environmental Studies (NIES) certified reference material (CRM) No. 28 Urban Aerosols, collected on the filters of a central ventilating system in a building in Beijing city center, was performed to obtain informative values of Hg isotopic composition and total Hg (THg) mass fraction. The THg mass fraction was determined by four organizations using atomic absorption spectrometry; it resulted in the mean value of 1.19 ± 0.12 mg/kg (2SD, n = 24). The Hg isotopic composition of the CRM was measured and intercompared at two different institutions by cold vapor generation system coupled to multicollector inductively coupled plasma mass spectrometry. Subsequently, a conventional dissolution method that uses a mixture of HNO3/HCl/H2O2 in Hotblock® and two different dissolution methods that use a mixture of HNO3/HCl with a microwave and a digestion bomb were applied. The Hg isotopic compositions were δ202Hg = - 1.26 ± 0.17‰, Δ199Hg = - 0.23 ± 0.06‰, Δ200Hg = 0.01 ± 0.07‰, and Δ201Hg = - 0.22 ± 0.09‰ (2SD, n = 18) for the conventional method, which agree well with those obtained using microwave and bomb digestion. Our results indicate that, for the quality control of particulate matter analyses, this CRM is appropriate for use in environmental and geochemical studies. Graphical abstract.

Potential of lead elemental and isotopic signatures for authenticity and geographical origin of Bordeaux wines.

Lead concentrations and lead isotope ratios of 43 authentic Bordeaux wines from prestigious châteaux and 14 suspicious Bordeaux origin were determined to evaluate their potential for authenticity and geographical origin assessment. Results have shown that the total Pb concentrations in Bordeaux wines drastically decreased over the previous 50 years with a clear shift of isotopic signatures towards geogenic values corresponding to an overall trend of European environmental lead monitoring. The Pb isotopic ratios determined in both series of samples clearly demonstrated that suspicious Bordeaux wines displayed Pb isotopic signatures statistically distinctive from those obtained for authentic wines. This observation was confirmed by the three-isotope mixing lines obtained between the geogenic and the anthropogenic Pb isotopes data that characterize European and Asian sources. The use these specific three-isotope plots allows a non-ambiguous discrimination between authentic Pauillac AOC and the counterfeited ones.

Strontium elemental and isotopic signatures of Bordeaux wines for authenticity and geographical origin assessment.

The 87Sr/86Sr ratio and Sr concentrations of 43 authentic Bordeaux wines from the world's most prestigious châteaux are presented in the context of their relation to the geographical origin of wine and authenticity. The results demonstrate relatively narrow spans of variabilities observed for 87Sr/86Sr ratio and Sr concentrations in authentic Bordeaux wines, which can be used with reasonable certainty as specific parameters for identifying regional wineries. For comparison, a set of imitated Bordeaux wines was studied for Sr isotopic and elemental compositions. A significant excess of both parameters in suspicious wines were found in reference to authentic values. Such natural and anthropogenically induced variations offer an enhanced discriminating potential of Sr. The unique Sr binary signature may detect imitated wines and trace genuine products from different regional wineries. The obtained results shown a promising perspective for wine authenticity control by means of Sr isotopic and elemental composition.

Assessment of Hg contamination by a Chlor-Alkali Plant in riverine and coastal sites combining Hg speciation and isotopic signature (Sagua la Grande River, Cuba).

Chlor-alkali plants (CAP) are recognized as major sources of mercury (Hg) in the environment. In this work, Hg concentration, speciation and isotopic signature were determined in sediments and biota (fish and oyster) from Sagua La Grande River (SG River) and the adjacent coastal zone in the vicinity of a CAP (Cuba). High Hg concentrations in surface sediments (up to 5072 ng g-1), mainly occurring as inorganic Hg, decrease with the distance from the CAP along the SG River and seaward. Meanwhile, Hg concentration and speciation in riverine catfish (Claria gariepinus) muscle (1093 ± 319 ng g-1, ˜70% as MeHg) and coastal oysters (Crassostrea rizophorae) (596 ± 233 ng g-1, ˜50% as MeHg) indicate a direct impact from CAP. Hg isotopic signature in sediments, following both mass dependent (MDF) and mass independent fractionation (MIF), exhibits a clear binary mixing between CAP pollution (+0.42‰, δ202Hg; -0.18‰, Δ201Hg) and regional background end-member (˜ -0.49‰, δ202Hg; +0.01‰, Δ201Hg). The combination of speciation and isotopic information in biota and sediments allows to trace Hg contamination pathways from contaminated sediments to the biota, establishing the importance of both methylation and demethylation extent in both river and coastal sites before Hg species bioaccumulation.

Multi-element isotopic signature (C, N, Pb, Hg) in epiphytic lichens to discriminate atmospheric contamination as a function of land-use characteristics (Pyrénées-Atlantiques, SW France).

Multi-elemental isotopic approach associated with a land-use characteristic sampling strategy may be relevant for conducting biomonitoring studies to determine the spatial extent of atmospheric contamination sources. In this work, we investigated how the combined isotopic signatures in epiphytic lichens of two major metallic pollutants, lead (206Pb/207Pb) and mercury (δ202Hg, Δ199Hg), together with the isotopic composition of nitrogen and carbon (δ15N, δ13C), can be used to better constrain atmospheric contamination inputs. To this end, an intensive and integrated sampling strategy based on land-use characteristics (Geographic information system, GIS) over a meso-scale area (Pyrénées-Atlantiques, SW France) was applied to more than 90 sampling stations. To depict potential relationships between such multi-elemental isotopic fingerprint and land-use characteristics, multivariate analysis was carried out. Combined Pb and Hg isotopic signatures resolved spatially the contribution of background atmospheric inputs from long range transport, from local legacy contamination (i.e. Pb) or actual industrial inputs (i.e. Pb and Hg from steel industry). Application of clustering multivariate analysis to all studied isotopes provided a new assessment of the region in accordance with the land-use characteristics and anthropogenic pressures.

Total As and As speciation from worldwide collected red wine samples.

Total As and As speciation were measured in 147 red wines collected worldwide by ICP-MS and HPLC-ICP-MS, respectively. The samples included mid-priced to prestigious wines with vintages covering a period of almost 50 years. Total As concentration ranged from below 0.1 to 56 µg/L (average value: 4.0 ± 5.9 µg/L). None of the samples presented a concentration exceeding the limit set by the Office of Vine and Wine of 200 µg/L. Inorganic As was the most abundant form, representing from about half to all total As, mainly as As(III). Dimethylarsinic-acid (DMA) was detected in slightly less than half of the samples, accounting for a few to several dozens of percent. Monomethylarsonic-acid (MMA) was only detected in a few samples. In average, the DMA concentration seemed to be higher in the Bordeaux wines than in the other ones, irrespective of the total As concentration.

Origins and discrimination between local and regional atmospheric pollution in Haiphong (Vietnam), based on metal(loid) concentrations and lead isotopic ratios in PM10.

Southeast Asia is a hotspot of anthropogenic emissions where episodes of recurrent and prolonged atmospheric pollution can lead to the formation of large haze events, giving rise to wide plumes which spread over adjacent oceans and neighbouring countries. Trace metal concentrations and Pb isotopic ratios in atmospheric particulate matter < 10 µm (PM10) were used to track the origins and the transport pathways of atmospheric pollutants. This approach was used for fortnightly PM10 collections over a complete annual cycle in Haiphong, northern Vietnam. Distinct seasonal patterns were observed for the trace metal concentration in PM10, with a maximum during the Northeast (NE) monsoon and a minimum during the Southeast (SE) monsoon. Some elements (As, Cd, Mn) were found in excess according to the World Health Organization guidelines. Coal combustion was highlighted with enrichment factors of As, Cd, Se, and Sb, but these inputs were outdistanced by other anthropogenic activities. V/Ni and Cu/Sb ratios were found to be markers of oil combustion, while Pb/Cd and Zn/Pb ratios were found to be markers of industrial activities. Pb isotopic composition in PM10 revealed an important contribution of soil dusts (45-60%). In PM10, the Pb fraction due to oil combustion was correlated with dominant airflow pathways (31% during the north-easterlies and 20% during the south-easterlies), and the Pb fraction resulting from industrial emissions was stable (around 28%) throughout the year. During the SE monsoon, Pb inputs were mainly attributed to resuspension of local soil dusts (about 90%), and during the NE monsoon, the increase of Pb inPM10 was due to the mixing of local and regional inputs.

Hg Compound-Specific Isotope Analysis at Ultratrace Levels Using an on Line Gas Chromatographic Preconcentration and Separation Strategy Coupled to Multicollector-Inductively Coupled Plasma Mass Spectrometry.

Stable Hg isotope analyses are nowadays widely employed to discriminate Hg sources and understand its biogeochemical cycle. Until now, total Hg isotopic compositions have been mainly used but Hg compound-specific isotopic analysis (CSIA) methodologies are emerging. Online Hg-CSIA were limited to samples containing high concentrations, but in this work we overcome this limitation for the measurement of inorganic (IHg) and monomethylmercury (MMHg) by gas chromatography hyphenated to multicollector-inductively coupled plasma mass spectrometry (GC/MC-ICPMS) through the use of an automated online preconcentration strategy, allowing injection volumes up to 100 times larger than usual. The preconcentration of Hg species and subsequent transfer to the column were achieved by a programmed temperature vaporization (PTV) injector fitted with a packed liner. The PTV parameters were first optimized using a quadrupole ICPMS, and then its suitability for Hg-CSIA was evaluated with long-term replicate analysis of various standards and reference materials (RMs). The large preconcentration capability enables analyses with Hg concentrations in the organic solvent 2 orders of magnitude lower than the previous conventional GC/MC-ICPMS method, but a compound specific standard bracketing procedure was required for MMHg in order to correct for the differential behavior of Hg species in the liner. The external reproducibility of the method ranged from 0.19 to 0.39 ‰ for Δ199Hg and δ202Hg (as 2 SD, n = 143-167) depending on the species. The analysis of various RMs demonstrated the applicability to environmental samples with species concentrations down to about 150 ng g-1. This new methodology opens the way for a much wider range of online Hg-CSIA measurements that will improve our understanding of the Hg biogeochemical cycle.

Seabird Tissues As Efficient Biomonitoring Tools for Hg Isotopic Investigations: Implications of Using Blood and Feathers from Chicks and Adults.

Blood and feathers are the two most targeted avian tissues for environmental biomonitoring studies, with mercury (Hg) concentration in blood and body feathers reflecting short and long-term Hg exposure, respectively. In this work, we investigated how Hg isotopic composition (e.g., δ202Hg and Δ199Hg) of blood and feathers from either seabird chicks (skuas, n = 40) or adults (penguins, n = 62) can accurately provide information on exposure to Hg in marine ecosystems. Our results indicate a strong correlation between blood and feather Hg isotopic values for skua chicks, with similar δ202Hg and Δ199Hg values in the two tissues (mean difference: -0.01 ± 0.25 ‰ and -0.05 ± 0.12 ‰, respectively). Since blood and body feathers of chicks integrate the same temporal window of Hg exposure, this suggests that δ202Hg and Δ199Hg values can be directly compared without any correction factors within and between avian groups. Conversely, penguin adults show higher δ202Hg and Δ199Hg values in feathers than in blood (mean differences: 0.28 ± 0.19‰ and 0.25 ± 0.13‰), most likely due to tissue-specific Hg temporal integration. Since feathers integrate long-term (i.e., the intermoult period) Hg accumulation, whereas blood reflects short-term (i.e., seasonal) Hg exposure in adult birds, the two tissues provide complementary information on trophic ecology at different time scales.

87Sr/86Sr isotope ratio and multielemental signatures as indicators of origin of European cured hams: The role of salt.

We have examined the potential of discriminant inorganic constituents (trace-, ultra-trace elements and Sr isotope ratios) to assess the origin of world famous brands of European dry-cured hams. The variation of the multielemental composition with principal component analysis allowed to discriminate the origin of Bayonne hams. Determined ratio 87Sr/86Sr was recognized as a strong additional distinctive parameter. The ratio 87Sr/86Sr allowed to better separate all the different categories of hams in addition to the multi-elemental detection. The major contribution of the value 87Sr/86Sr for the Bayonne ham is directly related to its curing due to the salt used in process coming from the nearby salt mine Salies-de-Béarn. Since the salt represents around 4% of the final product, it will therefore strongly influence the elemental and isotopic composition of hams. The overall discrimination potential of strontium isotope ratio is evidenced in the final statistical discrimination of the origin of hams.