Episodic accretion in protostars leads to luminosity outbursts that end up heating their surroundings. This rise in temperature pushes the snow lines back, enabling the desorption of chemical species ...from dust grain surfaces, which may significantly alter the chemical history of the accreting envelope. However, a limited number of extensive chemical surveys of eruptive young stars have been performed thus far. In the present study, we carry out a large spectral survey of the binary Class I protostar L1551 IRS 5, known to be a FUor-like object, in the 3 mm and 2mm bands with the IRAM-30m telescope. As a result, we detected more than 400 molecular lines. The source displays a great chemical richness with the detection of 75 species, including isotopologues. Among these species, there are 13 hydrocarbons, 25 N-bearing species, 30 O-bearing species, 15 S-bearing species, 12 deuterated molecules, and a total of 10 complex organic molecules (l-C 4 H 2 , CH 3 CCH, CH 2 DCCH, CH 3 CHO, CH 3 CN, CH 3 OCH 3 , CH 3 OCHO, CH 3 OH, CH 2 DOH, and HC 5 N). With the help of local thermodynamic equilibrium (LTE) and non-LTE models, we determined the column densities of most molecules as well as excitation and kinetic temperatures. While most of those molecules trace the cold envelope (≲20 K), the OCS and CH 3 OH emission arise from the warm (>100 K) innermost (<2″) regions. We compared the chemical inventory of L1551 IRS 5 and its column density ratios, including isotopic ratios, with other protostellar sources. A broad chemical diversity is seen among Class I objects. More observations with both single-dish telescopes and interferometers are needed to characterize the diversity in a larger sample of protostars, while more astrochemical models would help explain this diversity, in addition to the impact of luminosity outbursts on the chemistry of protostellar envelopes.
► Levels and trends of HBCDs and PFCs were studied in the French coastal environment. ► Results show widespread contamination of shellfish by α-HBCD and PFOS. ► Contamination by α-HBCD increased ...exponentially between 1981 and 2011. ► PFOS levels underwent a significant linear decrease over time.
The levels and congener patterns of HBCDs (hexabromocyclododecanes) and PFCs (perfluorinated compounds) were determined in filter-feeding molluscs collected in 2008 and 2010 along the coasts of mainland France. α-HBCD and PFOS (perfluorooctane sulfonate) were detected in all samples, revealing widespread contamination of the coastal environment by these emerging contaminants. The spatial distribution of Σ-HBCD concentrations showed higher median levels in samples from the Mediterranean Sea and English Channel respectively, i.e. 0.19ngg−1 wet weight (ww) and 0.08ngg−1 ww, related to high anthropogenic pressure from urban and industrial activities, while the median concentration was 0.05ngg−1 ww in samples from the Atlantic coast. Among PFCs, PFOS was the only compound detected in all samples and PFDA (perfluorodecanoic acid) was the second most frequently-detected compound. PFOS median concentrations were 0.18ngg−1 ww, 0.09ngg−1 ww and 0.04ngg−1 ww in samples from the English Channel, the Atlantic coast and the Mediterranean coast respectively. The highest PFOS concentration was found in the Loire estuary, possibly related to local industrial activities. The Mediterranean samples showed a different pattern, with predominant long-chain PFCAs (perfluorocarboxylic acids), suggesting the presence of alternative sources on the Mediterranean coast.
The temporal trends studied in archived samples from the Seine estuary site showed a significant exponential increase in HBCD concentrations between 1981 and 2011, with a doubling time of 7years, while PFOS levels underwent a significant linear decrease over time. These trends are coherent with current regulations on the use of these compounds. The results presented in this paper provide the first data on the contamination of the French coastal marine environment by the selected emerging compounds, and constitute a reference for the future monitoring of French coastal contamination by emerging contaminants.
This study explored the complementarity between targeted (TS) and non-targeted screening (NTS) based on liquid and gas-phase chromatography coupled to (high-resolution) mass spectrometry ...(LC-/GC-(HR)MS) for the comprehensive characterization of organohalogen fingerprints within a set of Lake Ontario lake trout samples. The concentrations of 86 legacy, emerging and novel halogenated compounds (HCs), were determined through 4 TS approaches involving no less than 6 hyphenated systems. In parallel, an innovative NTS strategy, involving both LC and GC-Q-Orbitrap, was implemented to specifically highlight halogenated signals. Non-targeted HRMS data were processed under the HaloSeeker software based on Cl and Br isotopic ratio and mass defect to extend the screening to unsuspected and unknown HCs. A total of 195 halogenated mass spectral features were characterized in the Lake Ontario lake trout, including well known HCs (PCBs, PBDEs, PBBs, DDT and their degradation products), emerging HCs (novel brominated flame retardants, short-, medium- and long-chain chlorinated paraffins) or suggested molecular formula (mainly polychlorinated ones). Among the 122 HCs highlighted by TS, only 21 were identified by NTS. These results fueled a discussion on the potential and limitations of both approaches, and the current position of NTS within environmental and health monitoring programs.
Display omitted
•Complementarity of targeted and non-targeted screening of organohalogens is studied.•Targeted quantification of legacy and novel BFRs, CPs and PCBs (n > 80).•Non-targeted screening (LC- and GC- Q-Orbitrap) offers complementary fingerprints.•Non-targeted screening highlights unexpected organohalogens.
Determination of the occurrence levels of legacy and novel BFRs is today required to better understand the trends of BFRs contamination in food consecutive to the EU PBDEs restrictions and to proceed ...to a recent human food exposure in parallel. Therefore, concentrations of a large set of brominated flame retardants (BFRs) (n = 27) including PBDEs, HBCDDs, TBBPA and novel flame retardants (nBFRs) have been determined in more than 600 food and feed samples collected between 2014 and 2016 in the context of French monitoring plans. Although legacy BFRs had already been studied in France, such a survey constituted the very first determination of nBFRs occurrence in foodstuffs at the national level. The concentration levels measured in fish and fish products were in general higher than in the other food categories. PBDEs were detected in 70% of the samples and were observed as the most abundant congeners (representing 80% of the sum of the monitored BFRs), while α-HBCDD could also be considered as a predominant congener (up to 26% of the sum of the monitored BFRs in fishes). nBFRs concentration levels were most of the time below the LOQ, except PBT, PBBz and HBBz which were more frequently detected at low levels. Also investigated in the study, BRPs exhibited high concentration levels in crustaceous (maximum value > 2700 pg/g ww).
•Occurrence of BFRs in feed and food of animal origin in the 2014–2016 period in France.•Comparison between legacy and novel BFR contaminations.•Very low decrease of legacy BFRs occurrence levels in fish and sea products despite the regulation implementation.
In recent decades, stormwater management has developed to allow stormwater to infiltrate directly into the soils instead of being collected and routed to sewer systems. However, during infiltration, ...stormwater creates a sediment deposit at the soil surface as the result of high loads of suspended particles (including pollutants), leading to the settlement of sedimentary layers prone to colonization by plants and earthworms. This study aims to investigate the earthworm communities of a peculiar infiltration basin and investigate the influence of edaphic conditions (water content, organic matter content, pH, height of sediment) and of persistent organic pollutants (POPs: PCBs, PCDDs and PCDFs) on these earthworms. Attention was paid to their age (juveniles or adults) and their functional group (epigeic, endogeic, anecic). We found that the earthworm abundance was mostly driven by edaphic conditions, with only a slight impact of POPs, with a significant negative impact of PCBDLno for juveniles and endogeic, and PCDDs for epigeic. On the contrary, the height of the sediment and the water content are beneficial for their presence and reproduction. Furthermore, POPs contents are also linked to physicochemical parameters of the sediment. Bioaccumulation was clearly revealed in the studied site but does not differ between juveniles and adults, except for PCDDs. Conversely, BAF values seemed to vary between functional groups, except for PCBDL non-ortho. It strongly varies with the family types (PCBs versus PCCD/Fs) and between congeners within the same family, with specific strong bioaccumulation for a few congeners.
Display omitted
•Characterization of earthworm communities in an infiltration basin with POPs.•Earthworm density high with a large spatial variability.•Earthworm density more related to edaphic conditions than POPs contents.•But, some POPs have significant negative effect on some earthworm groups.•Bioaccumulation factor moderate with high values for certain POPs and congeners.
The present study compares concentrations and chemical profiles of an extended range of persistent organic pollutants (dioxins, polychlorobiphenyls, brominated flame retardants and organochlorine ...pesticides) in breast milk samples from French (n = 96), Danish (n = 438) and Finnish (n = 22) women. Median exposure levels observed in French women (WHO-TEQ2005 PCDD/F = 6.1 pg/g l.w., WHO-TEQ2005 dl-PCB = 4.3 pg/g l.w., sum of 6 ndl-PCB = 85.2 ng/g l.w., sum of 7 i-PBDE = 1.5 ng/g l.w.) appeared overall lower than in Danish and Finnish women for all examined POPs, except for α-HBCD (2-fold higher level at 0.6 ng/g l.w.). Furthermore, the observed exposure levels of dioxins and PCBs were higher in Danish women (WHO-TEQ2005 PCDD/F = 13.2 pg/g l.w., WHO-TEQ2005 dl-PCB = 6.6 pg/g l.w., sum of 6 ndl-PCB = 162.8 ng/g l.w.) compared to Finnish women (WHO-TEQ2005 PCDD/F = 9.0 pg/g l.w., WHO-TEQ2005 dl-PCB = 4.6 pg/g l.w., sum of 6 ndl-PCB = 104.0 ng/g l.w.), whereas the concentrations of PBDEs were similar for Danish and Finnish women (sum of 7 i-PBDE = 4.9 and 5.2 ng/g l.w. respectively). The organochlorine (OC) pesticide contamination profile, determined in a subset of French samples, was dominated by p,p’-DDE (56.6%), followed by β-HCH (14.2%), HCB (9.7%) and dieldrin (5.2%), while other compounds were only minor contributors (<5%). The three countries appeared to be discriminated by the observed contamination patterns of the PCDD/F versus PCB, and the 1,2,3,6,7,8-HxCDD versus 1,2,3,4,7,8-HxCDD ratios, in addition to the relative contributions of specific congeners to the contamination profile (PCBs #118 and #156, PBDEs #28, #47, #99 and #153). In conclusion, unique chemical signatures were observed for each country on the basis of some POP congeners. Future biomonitoring studies will need to consider the high variability of individual exposure profiles in relation to multiple exposure sources but also physiological and metabolic differences.
•A set of 78 POPs was determined in Danish, Finish and French breast milk samples.•Exposure levels appeared lower in French women except for α-HBCD.•Country-specific exposure patterns were observed among the analyzed samples.•Lifestyle, genetic polymorphisms and metabolism factors may explain these patterns.
Specific internal exposure patterns are observed in terms of POP contamination profiles in breast milk of Danish, Finish versus French women.
We study a commonly-used second-kind boundary-integral equation for solving the Helmholtz exterior Neumann problem at high frequency, where, writing
Γ
for the boundary of the obstacle, the relevant ...integral operators map
L
2
(
Γ
)
to itself. We prove new frequency-explicit bounds on the norms of both the integral operator and its inverse. The bounds on the norm are valid for piecewise-smooth
Γ
and are sharp up to factors of
log
k
(where
k
is the wavenumber), and the bounds on the norm of the inverse are valid for smooth
Γ
and are observed to be sharp at least when
Γ
is smooth with strictly-positive curvature. Together, these results give bounds on the condition number of the operator on
L
2
(
Γ
)
; this is the first time
L
2
(
Γ
)
condition-number bounds have been proved for this operator for obstacles other than balls.
The systemic imidacloprid is one of the most used insecticides in the world for field and horticultural crops. This neurotoxicant is often used as seed-dressing, especially for maize, sunflower, and ...rape. Using a LC/MS/MS technique (LOQ = 1 μg/kg and LOD = 0.1 μg/kg), the presence of imidacloprid has been measured in maize from field samples at the time of pollen shed, from less than 0.1 μg/kg up to 33.6 μg/kg. Numerous random samples were collected throughout France from 2000 to 2003. The average levels of imidacloprid measured are 4.1 μg/kg in stems and leaves, 6.6 μg/kg in male flowers (panicles), and 2.1 μg/kg in pollen. These values are similar to those found previously in sunflower and rape. These results permit evaluation of the risk to honeybees by using the PEC/PNEC ratios (probable exposition concentrations/predicted no effect concentration). PEC/PNEC risk ratios were determined and ranged between 500 and 600 for honeybees foraging on maize treated with imidacloprid by seed dressing. Such a high risk factor can be related to one of the main causes of honeybee colony losses. Keywords: Imidacloprid; maize; corn; pollen; flowers; systemic insecticide; honeybees
A 1 km² mountainous karst watershed on the Larzac Plateau in Southern France.
The village of La Vacquerie, located at the outlet of the watershed, is punctually affected by flash floods during storm ...events. On the contrary, no runoff is observed in the village during other rainfalls. A sinkhole, draining surface flows at the entrance of the village, plays a role on these differences. Descriptions of short and intense rainfalls in 2015 (avg. 40 mm/h over 5 h) and long and light events in 2014/2016 (avg. 8 mm/h over 25 h) provide valuable data to calibrate inputs of a distributed physic-based flow model, in particular the sinkhole drainage capacity. This study aims to quantify drainage capacity changes with rainfall characteristics and to find the rain intensity threshold at which runoff exceeds sinkhole capacity.
The hydrological water balance of the hydrosystem is affected by the intensity variations for each of the different rain events. It shows the limited part of drainage in sinkhole (10%) during long light rains but its significant increase (40%) during short and intense rains. Drainage in sinkhole is affected by intensity variations rather than by the total amount of precipitation. When intensity exceeds 110 mm/h the sinkhole is submerged. However, this result is obtained in a case of Plateau configuration, where the saturated level, located deep below the surface (here 500 m), does not retro-affect drainage in the sinkhole.
Display omitted
•We study a 1 km² mountainous karst watershed during four intense or light rain events.•A sinkhole located at the outlet of the watershed permits fast drainage during rains.•Hydrological balance is affected by changes of rain intensity rather than of duration.•Above an intensity threshold of 110 mm/h the sinkhole is flooded and runoffs increase.•Part of infiltration in the sinkhole can reach up to 40% in this watershed.
•We developed a sensitive gas chromatography tandem mass spectrometry method for the determination of bisphenol A in foodstuffs.•We carried out a full validation.•Environmental contamination and ...analytical pitfalls are discussed.•The method allows the quantification at low trace level: sub 0.1μgkg−1.•Efficiency has been assessed in the frame of the 2nd French Total Diet Study (TDS).
BPA-containing products are widely used in foodstuffs packaging as authorized within the European Union (UE no. 10/2011). Therefore, foods and beverages are in contact with BPA which can migrate from food contact material to foodstuffs. An accurate assessment of the exposure of the consumers to BPA is crucial for a non-ambiguous risk characterization. In this context, an efficient analytical method using gas chromatography coupled to tandem mass spectrometry (GC–MS/MS), in the selected reaction monitoring (SRM) mode, was developed for the quantification of BPA in foodstuffs at very low levels (<0.5μgkg−1). A standard operating procedure, based on the combination of two successive solid phase extractions (SPE), was developed for various liquid and solid foodstuffs. The use of 13C12-BPA as internal standard allowed accurate quantification of BPA by isotopic dilution. Control charts based on both blank and certified materials have been implemented to ensure analytical data quality. The developed analytical method has been validated according to in-house validation requirements. R2 was better than 0.9990 within the range 0-100μgkg−1, the trueness was 4.2%. Repeatability and within-laboratory reproducibility ranged from 7.5% to 19.0% and 2.5% to 12.2%, respectively, at 0.5 and 5.0μgkg−1 depending on the matrices tested for. The detection and quantification limits were 0.03 and 0.10μgkg−1, respectively. The reporting limit was 0.35μgkg−1, taking into account the mean of the laboratory background contamination. The global uncertainty was 22.2% at 95% confidence interval.
PDF
