Efficient collection and preparation of methane from low concentration waters for natural abundance radiocarbon analysis

K. J. Sparrow; J. D. Kessler
2017 | Limnol Oceanogr Methods

Freshwater and marine environments constitute the largest global reservoirs of the greenhouse gas methane (CH4) and natural abundance radiocarbon measurements (14C-CH4) can allow for high confidence interpretations about CH4 dynamics operating in these environments. Collecting sufficient amounts of CH4 sample for a standard, high precision 14C-accelerator mass spectrometry (AMS) analysis (∼ 200 μg carbon (C)) was previously unfeasible when sampling from low CH4 concentration waters, such as much of the surface ocean (∼ 2 nM), which would require collecting the CH4 from 8500 L of seawater. The method described here involves pumping 20,000–40,000 L of seawater up from depth through a dissolved gas extraction system, which enables the collection of a sample composed of 100s of L of gas in less than 4 h on station. The large volume extracted gas sample is compressed into a 1.7 L cylinder for transport from the ship to the home laboratory. The home laboratory preparation of each sample to a CH4-derived carbon dioxide aliquot for 14C-AMS analysis is carried out in 3 h on a flow-through vacuum line that simultaneously prepares aliquots for stable isotope analyses (δ13C-CH4 and δ2H-CH4). The total process blank of the method is small (5.0 μg CH4-C) and composes 1.2% of the average collected and prepared sample (424 ± 163 μg, from a recent campaign; n = 16). The 14C-CH4 blanks prepared on the vacuum line have acceptably low 14C content (0.23 ± 0.07 percent Modern Carbon (pMC); n = 7) relative to the 14C-dead (0 pMC) CH4 from which they are prepared.

Per- and polyfluoroalkyl substances (PFASs) in San Francisco Bay wildlife: Temporal trends, exposure pathways, and notable presence of precursor compounds

Sedlak, MD; Benskin, JP; Wong, A; Grace, R; Greig DJ.
2017 | Chemosphere

Adductomic Screening of Hemoglobin Adducts and Monitoring of Micronuclei in School-Age Children

Carlsson H.; Aasa J.; Kotova N.; Vare D., Sousa P.; Rydberg, P.; Abramsson-Zetterberg L.; Törnqvist M.
2017 | Chem. Res. Toxicol. | 30 (5) (1157-1167)

Electrophilic compounds/metabolites present in humans, originating from endogenous processes or exogenous exposure, pose a risk to health effects through their reactions with nucleophilic sites in proteins and DNA, forming adducts. Adductomic approaches are developed to screen for adducts to biomacromolecules in vivo by mass spectrometry (MS), with the aim to detect adducts corresponding to unknown exposures from electrophiles. In the present study, adductomic screening was performed using blood samples from healthy children about 12 years old (n = 51). The frequencies of micronuclei (MN) in erythrocytes in peripheral blood were monitored as a measure of genotoxic effect/genotoxic exposure. The applied adductomic approach has been reported earlier by us and is based on analysis of N-terminal valine adducts in hemoglobin (Hb) by liquid chromatography tandem mass spectrometry (LC-MS/MS). High resolution MS was introduced for refined screening of previously unknown N-terminal Hb adducts. Measured adduct levels were compared with MN frequencies using multivariate data analysis. In the 51 individuals, a total of 24 adducts (whereof 12 were previously identified) were observed and their levels quantified. Relatively large interindividual variations in adduct levels were observed. The data analysis (with partial least-squares regression) showed that as much as 60% of the MN variation could be explained by the adduct levels. This study, for the first time, applies the combination of these sensitive methods to measure the internal dose of potentially genotoxic chemicals and genotoxic effects, respectively. The results indicate that this is a valuable approach for the characterization of exposure to chemical risk factors for the genotoxic effects present in individuals of the general population.

An academic researcher’s guide to increased impact on regulatory assessment of chemicals.

Ågerstrand ; Sobek A; Lilja K; Linderoth M; Wendt-Rasch L; Wernersson A-S; Rudén C.
2017 | Environ. Sci.: Processes Impacts

The interactions between academic research and regulatory assessment of chemicals may in theory seem straightforward: researchers perform studies, and these studies are used by regulators for decision-making. However, in practice the situation is more complex, and many factors decide a research study’s regulatory use. According to several EU chemical legislations, all available and relevant studies can be used in hazard and risk assessment of chemicals. However, in practice, standard tests conducted under GLP and sponsored and provided by industry are predominantly used. Peer-reviewed studies from independent sources are often disregarded or disputed since they often do not comply with regulatory data requirements and quality criteria. There are several possible reasons for this, one being that academic research is reported in a way that does not fit the regulatory requirements. To help bridge such a gap, the aim of this paper is to give an overview of the general workings of chemicals legislation and propose a set of actions to increase the usability of research data. In the end, this may increase the use of academic research for decision-making and ultimately result in more science-based policies. From a policy perspective, useful scientific evidence are those studies that are sufficiently reliable and relevant. This is not in contradiction to the aims of research and generally accepted scientific standards.

Export of calcium carbonate corrosive waters from the East Siberian Sea

Leif G. Anderson; Jörgen Ek; Ylva Ericson; Christoph Humborg; Igor Semiletov; Marcus Sundbom; Adam Ulfsbo
2017 | Biogeosciences | 14 (1811-1823)
acidification , arctic-ocean , carbon cycle , SWERUS

The Siberian shelf seas are areas of extensive biogeochemical transformation of organic matter, both of marine and terrestrial origin. This in combination with brine production from sea ice formation results in a cold bottom water of relative high salinity and partial pressure of carbon dioxide (pCO2). Data from the SWERUS-C3 expedition compiled on the icebreaker Oden in July to September 2014 show the distribution of such waters at the outer shelf, as well as their export into the deep central Arctic basins. Very high pCO2 water, up to ∼ 1000 µatm, was observed associated with high nutrients and low oxygen concentrations. Consequently, this water had low saturation state with respect to calcium carbonate down to less than 0.8 for calcite and 0.5 for aragonite. Waters undersaturated in aragonite were also observed in the surface in waters at equilibrium with atmospheric CO2; however, at these conditions the cause of under-saturation was low salinity from river runoff and/or sea ice melt. The calcium carbonate corrosive water was observed all along the continental margin and well out into the deep Makarov and Canada basins at a depth from about 50 m depth in the west to about 150 m in the east. These waters of low aragonite saturation state are traced in historic data to the Canada Basin and in the waters flowing out of the Arctic Ocean north of Greenland and in the western Fram Strait, thus potentially impacting the marine life in the North Atlantic Ocean.

NanoCRED: A transparent framework to assess’ the regulatory adequacy of ecotoxicity data for nanomaterials – Relevance and reliability revisited

Nanna B. Hartmann; Marlene Ågerstrand; Hans-Christian Holten Lützhøft; Anders Baun
2017 | NanoImpact | 6 (81-89)

Environmental hazard and risk assessment serve as the basis for regulatory decisions to protect the environment from unintentional adverse effects of chemical substances including nanomaterials. This process requires reliable and relevant environmental hazard data upon which classification and labelling can be based and Predicted No-Effect Concentration (PNEC) values can be estimated. In a regulatory context ecotoxicological data is often recommended to be generated according to accepted and validated test guidelines, preferably also following Good Laboratory Practice. However, engineered nanomaterials are known to behave very differently in ecotoxicity tests compared to the conventional soluble chemicals, for which most guidelines were developed. Therefore non-guideline tests, or tests following modified test guidelines, can provide valuable information and should not per se be considered less adequate for regulatory use. Here we propose a framework for reliability and relevance evaluation of ecotoxicity data for nanomaterials that take into account the challenges and characterisation requirements associated with testing of these substances. The nanoCRED evaluation criteria, and accompanying guidance, were developed to be used in combination with those developed through the ‘Criteria for Reporting and Evaluating Ecotoxicity Data (CRED)’ project. This approach can accommodate all types of nanomaterials, all types of aquatic ecotoxicity studies, and qualitative as well as quantitative data evaluation requirements. Furthermore, it is practically feasible to implement and directly applicable in European as well as international regulatory frameworks.

Ambient observations of dimers from terpene oxidation in the gas-phase: implications for new particle formation and growth

Claudia Mohr, Felipe D. Lopez‐Hilfiker, Taina Yli‐Juuti, Arto Heitto, Anna Lutz, Mattias Hallquist, Emma L. D'Ambro, Matti P. Rissanen, Liqing Hao, Siegfried Schobesberger, Markku Kulmala, Roy L. Mauldin III, Ulla Makkonen, Mikko Sipilä, Tuukka Petäjä, Joel A. Thornton
2017 | Geophys Res Lett | 44 (2958-2966)

Toward a comprehensive global emission inventory of C4–C10 perfluoroalkane sulfonic acids (PFSAs) and related precursors: focus on the life cycle of C8-based products and ongoing industrial transition

Wang, Z.; Boucher, J.M.; Scheringer, M.; Cousins, I.T.; Hungerbuehler, K.
2017 | Environ. Sci. Technol. | 18 (51) (4482-4493)

Assessment of dietary exposure to organohalogen contaminants, legacy and emerging flame retardants in a Norwegian cohort

Xu, F.; Tay, J. H.; Covaci, A.; Padilla-Sanchez, J. A.; Papadopoulou, E.; Haug, L. S.; Neels, H.; Sellstrom, U.; de Wit, C. A.
2017 | Environ Int | 102 (236-243)

Polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), emerging halogenated flame retardants (EHFRs) and organophosphate flame retardants (PFRs) were detected in 24h duplicate diet samples from a Norwegian cohort (n=61), with concentrations ranging from

Water-to-air transfer of branched and linear PFOA: Influence of pH, concentration and water type

Johansson, J.H.; Yan, H.; Berger, U.; Cousins, I.T.
2017 | Emerging Contaminants | 3 (1) (46-53)

Temperature versus hydrologic controls of chemical weathering fluxes from United States forests

Peter A. Raymond
2017 | Chem. Geol.

Chemical weathering is a dominant control on modern inland water chemistry and global element budgets over geologic time scales. Due to its central role in the earth's biogeochemistry it remains an intense area of interest. Understanding the controls on chemical weathering is difficult because it has many drivers with overlapping temporal and spatial signals. Of particular interest is the relationship between chemical weathering fluxes and global temperatures due to a negative feedback loop where warmer temperatures leads to more chemical weathering and its associated atmospheric CO2 consumption (Berner et al., 1983). Recently it has been proposed that this negative feedback loop is indirect where the acceleration of the hydrologic cycle by increased global temperatures leads to higher chemical weathering and atmospheric CO2 consumption (Maher and Chamberlain, 2014). Here, fluxes of all major cations and anions are calculated for 150 forested watersheds smaller than 500 km2 in order to explore controls on chemical weathering from United States forests. Relationships between watershed hydrology, ion ratios and pH are reported that explain a large amount of across site variation in bicarbonate fluxes. Furthermore, across all watersheds ~ 32% of the cation flux is not balanced by bicarbonate but by sulfate. Paired alkalinity, temperature and discharge data are used to determine a temperature sensitivity of chemical weathering across 51 forested watersheds with a minimum of 70 measurements. The temperature sensitivity of bicarbonate fluxes is absent at low flow conditions because long residence times leads to chemical equilibrium and transport limitation. As discharge increases and residence time decreases, the temperature sensitivity of chemical weathering is released from transport limitation. The temperature sensitivity then increases with discharge until it levels off at high discharges as the system becomes reaction limited. Records of daily discharge, watershed discharge to flux relationships, and the temperature sensitivity are then used to estimate how chemical fluxes would change with a 20% increase in discharge, and 10° increase in temperature global change scenario. Not surprisingly it is found that increased discharge leads to higher weathering fluxes. Interestingly, wetter years have a higher temperature sensitivity due to a release of the temperature sensitivity from transport limitation. This coupled with a strong direct temperature effect leads to an approximately equal response from temperature and increased discharge using this scenario of global change. Thus periods of time and regions that are subject to both warm and wet conditions may have a particularly strong control on weathering fluxes.

Case study on screening new emerging pollutants in urine and nails.

Alves, A.; Giovanoulis, G.; Nilsson, U.; Erratico, C.; Lucattini, L.; Haug, L.; Jacobs, G.; de Wit, C.A.; Leonards, P.; Covaci, A.; Magnér, J.; Voorspoels, S.
2017 | Environ. Sci. Technol. | 51 (4046-4053)

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