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Tracing Dissolved Lead Sources in the Canadian Arctic: Insights from the Canadian GEOTRACES Program

Year: 2019
Products: low-flow PFA-Teflon nebulizer
Authors: Colombo, M;Rogalla, B;Myers, P;Allen, S;Orians, K;
Journal: ACS Earth Space Chem.

This study addresses an important knowledge gap in the distribution of lead (Pb) in the Arctic Ocean, by presenting dissolved Pb concentrations from samples collected during the GEOTRACES Canadian cruise in 2015. Dissolved Pb showed an increase in concentration from the Canada Basin toward Baffin Bay and the Labrador Sea. Canada Basin was the most isolated region from anthropogenic Pb inputs with low background concentrations (1.4−6.2 pmol kg−1 ) across most of the basin, although higher Pb features from the advection of Pacific-derived waters and sea ice meltwater were present. Likewise, high-Pb peaks (13.5−26.6 pmol kg−1 ) along narrow isopycnal surfaces (σθ, 27.4−27.6) in Baffin Bay were attributed to the advection of North Atlantic waters spreading a high-Pb signature into the bay, contrasting with the low values (2.5−7.4 pmol kg−1 ) present in the mixed layer, Arctic and Baffin Bay deep waters. The Labrador Sea, largely influenced by the recirculation of North Atlantic waters, had the highest Pb concentrations (∼17−34 pmol kg−1 ) measured in this study. The Canadian Arctic Archipelago (CAA) represents a transition environment influenced by Arctic waters imprinting a low-Pb signature in the western CAA and the southern side of Parry Channel, while Baffin Bay waters prevailed in the eastern CAA recirculating westward along the northern side of Parry Channel and progressively losing their relatively high Pb signature. Extremely low concentrations were measured in Canada Basin and CAA waters, which reflect the remoteness of this region from anthropogenic inputs as well as the old ventilation age of deep waters’ masses, providing a baseline for assessing future Pb studies. Finally, we successfully integrate modeling data with field observations demonstrating that dissolved lead, due to its distinctive anthropogenic signature in North Atlantic waters, can be a useful complementary tracer of water masses in the Canadian Arctic Ocean.

Copper speciation in different marine ecosystems around New Zealand

Year: 2019
Products: seaFAST
Authors: Zitoun, R;
Journal: Thesis

Copper (Cu) is an important bioactive trace metal in the marine environment, acting as an essential micronutrient for many marine species. However, it can also be harmful at elevated concentrations, triggering sub-lethal and toxic effects. During the last few decades, studies using electrochemical techniques have established that it is the particular chemical form of Cu, its so-called chemical speciation, and not its total concentration that controls the geochemical and biological behaviour and thus the bioavailability and toxicity of Cu in marine systems. The majority of dissolved Cu in the marine environment is strongly complexed by a heterogeneous mixture of Cu-binding organic ligands (L), reducing the free ionic Cu concentration ([Cu2+]) to femto- and picomolar levels. Free ionic Cu is generally considered the most bioavailable and thus the most beneficial or toxic form to marine organisms. Organic complexation reduces [Cu2+] in most marine systems to levels harmless, but above limitation, to many marine microorganisms. Measuring the inorganic, organic, and free Cu forms in the dissolved phase is critical to assess the fate (i.e., distribution, cycling, and reactivity) and the biological effects of Cu in the marine environment. However, the chemical speciation of Cu in natural saline waters is complex and is technically challenging to evaluate, resulting in cost-intensive and timeconsuming analyses. Consequently, despite the recognised importance, little data exists for Cu speciation and Cu-binding ligands in the marine environment, and ligand sources and chemical identities are generally understudied. Additionally, environmental processes and factors influencing and controlling Cu speciation in marine systems are still poorly understood. As a result, four different marine systems (i.e., estuarine, coastal and open ocean waters, as well as a shallow low-temperature hydrothermal vent system) were studied around New Zealand in an effort to advance the current understanding of Cu speciation processes and Cu-binding ligands in the marine environment. Total dissolved Cu concentrations were analysed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), while Cu speciation was assessed with adsorptive cathodic stripping voltammetry (AdCSV) with salicylaldoxime (SA) as the competing ligand.

Development of novel methods to evaluate availability of zinc, selenium and manganese in Atlantic salmon (Salmo salar)

Year: 2019
Products: FAST
Authors: Silva, MS;
Journal: Thesis

During the recent years, the composition of salmonids diets has changed from the use of mainly marine-based ingredients (e.g. fish meal and fish oil) to an increased use of plant-based ingredients (e.g. soybean meal and vegetable oil). These changes in diet composition have an impact on the mineral concentration and mineral availability. For instance, zinc (Zn) is naturally present in both fish meal and plant-based ingredients, but in different concentrations. The Zn concentration is usually higher in fish meal than in plant-based ingredients so, with the increased use of plant-based ingredients the Zn concentration tends to decrease in the basal mixes. In addition, compounds from plantbased ingredients can reduce mineral availability. For instance, phytic acid, which is typically found in plant-based ingredients, can decrease mineral availability due to its high binding affinity for metal ions. Therefore, minerals such as Zn, selenium (Se) and manganese (Mn) are supplemented to diets to cover the nutritional requirement of farmed fish. These minerals may be added as organic or inorganic forms. Taken all of this information into consideration, there is a need to study mineral availability in the current salmon feed composition which is formulated mainly using plant-based ingredients. Further knowledge in this area will provide a better understanding regarding mineral availability and necessary strategies to increase mineral availability in Atlantic salmon. Increasing mineral availability will promote fish health and robustness, but also decrease the environmental load via faeces.

Palladiumin talteenotto yhdyskuntajätevesilietteestä

Year: 2019
Products: prepFAST
Authors: Dahl, O;
Journal: Thesis

Kriittiset raaka-aineet ovat alkuaineita, joilla on suuri taloudellinen merkitys, mutta niiden saatavuus aiheuttaa huolta. Tällaisia alkuaineita ovat mm. platinaryhmän metallit sekä harvinaiset maametallit. Kriittisillä raaka-aineilla on suuri merkitys suunniteltaessa kiertotaloutta, jolloin alkuaineita käytettäisiin ja kierrätettäisiin mahdollisimman tehokkaasti.1 Jätevesiliete on jätevedenpuhdistamolla muodostuvaa lietettä, jota muodostuu jätevesien käsittelyprosesseissa. Lietettä muodostuu niin kotitalouksien ja teollisuuden vesien kuin katujen hulevesien käsittelystä. Liete sisältää ravinteiden ja hyödyllisten orgaanisten aineiden lisäksi myös haitallisia raskasmetalleja ja patogeeneja.2 Lietteen on havaittu myös sisältävän arvokkaita jalometalleja sekä harvinaisia maametalleja. Etenkin jalometallien on havaittu rikastuneen lietteeseen, jolloin liete voisi olla potentiaalinen jalometallien sekundäärinen lähde.

Re-Evaluating the Age of Deep Biosphere Fossils in the Lockne Impact Structure

Year: 2019
Products: ArF excimer laser ablation system
Authors: Tillberg, M;Ivarsson, M;Drake, H;Whitehouse, M;Kooijman, E;Schmitt, M;
Journal: Geosciences

Impact-generated hydrothermal systems have been suggested as favourable environments for deep microbial ecosystems on Earth, and possibly beyond. Fossil evidence from a handful of impact craters worldwide have been used to support this notion. However, as always with mineralized remains of microorganisms in crystalline rock, certain time constraints with respect to the ecosystems and their subsequent fossilization are difficult to obtain. Here we re-evaluate previously described fungal fossils from the Lockne crater (458 Ma), Sweden. Based on in-situ Rb/Sr dating of secondary calcite-albite-feldspar (356.6 ± 6.7 Ma) we conclude that the fungal colonization took place at least 100 Myr after the impact event, thus long after the impact-induced hydrothermal activity ceased. We also present microscale stable isotope data of 13C-enriched calcite suggesting the presence of methanogens contemporary with the fungi. Thus, the Lockne fungi fossils are not, as previously thought, related to the impact event, but nevertheless have colonized fractures that may have been formed or were reactivated by the impact. Instead, the Lockne fossils show similar features as recent findings of ancient microbial remains elsewhere in the fractured Swedish Precambrian basement and may thus represent a more general feature in this scarcely explored habitat than previously known.

Pre-Columbian Fire Management Linked to Refractory Black Carbon Emissions in the Amazon

Year: 2019
Products: Apex-Q
Authors: Arienzo, M;Maezumi, S;Chellman, N;Iriarte, J;
Journal: Fire

Anthropogenic climate change—combined with increased human-caused ignitions—is leading to increased wildfire frequency, carbon dioxide emissions, and refractory black carbon (rBC) aerosol emissions. This is particularly evident in the Amazon rainforest, where fire activity has been complicated by the synchronicity of natural and anthropogenic drivers of ecological change, coupled with spatial and temporal heterogeneity in past and present land use. One approach to elucidating these factors is through long-term regional fire histories. Using a novel method for rBC determinations, we measured an approximately 3500-year sediment core record from Lake Caranã in the eastern Amazon for rBC influx, a proxy of biomass burning and fossil fuel combustion. Through comparisons with previously published records from Lake Caranã and regional evidence, we distinguished between local and regional rBC emission sources demonstrating increased local emissions of rBC from ~1250 to 500 calendar years before present (cal yr BP), coinciding with increased local-scale fire management during the apex of pre-Columbian activity. This was followed by a regional decline in biomass burning coincident with European contact, pre-Columbian population decline, and regional fire suppression associated with the rubber boom (1850–1910 CE), supporting the minimal influence of climate on regional burning at this time. During the past century, rBC influx has rapidly increased. Our results can serve to validate rBC modeling results, aiding with future predictions of rBC emissions and associated impacts to the climate system.

Inputs and processes affecting the distribution of particulate iron in the North Atlantic along the GEOVIDE (GEOTRACES GA01) section

Year: 2019
Products: quartz cyclonic spray chamber
Authors: Gourain, A;Planquette, H;Cheize, M;
Journal: ETH Zurich Research Collection

The aim of the GEOVIDE cruise (May–June 2014, R/V Pourquoi Pas?) was to provide a better understanding of trace metal biogeochemical cycles in the North Atlantic Ocean. As marine particles play a key role in the global biogeochemical cycle of trace elements in the ocean, we discuss the distribution of particulate iron (PFe), in relation to the distribution of particulate aluminium (PAl), manganese (PMn), and phosphorus (PP). Overall, 32 full vertical profiles were collected for trace metal analyses, representing more than 500 samples. This resolution provides a solid basis for assessing concentration distributions, elemental ratios, size fractionation, and adsorptive scavenging processes in key areas of the thermohaline overturning circulation. Total particulate iron concentrations ranged from as low as 9 pmol L−1 in surface waters of the Labrador Sea to 304 nmol L−1 near the Iberian margin, while median PFe concentrations of 1.15 nmol L−1 were measured over the sub-euphotic ocean interior. Within the Iberian Abyssal Plain, the ratio of PFe to PAl was identical to the continental crust molar ratio (0.21 mol mol−1 ), indicating the important influence of crustal particles in the water column. Overall, the lithogenic component explained more than 87% of PFe variance along the section. Within the Irminger and Labrador basins, the formation of biogenic particles led to an increase in the PFe/PAl ratio (up to 0.64 mol mol−1 ) compared to the continental crust ratio. Continental margins induce high concentrations of particulate trace elements within the surrounding water masses (up to 10 nmol L−1 of PFe). For example, horizontal advection of PFe was visible more than 250 km away from the Iberian margin. Additionally, several benthic nepheloid layers were observed more than 200 m above the seafloor along the transect, especially in the Icelandic, Irminger, and Labrador basins, suspending particles with high PFe content of up to 89 nmol L−1.

Methodenentwicklung und Validierung von neuen Verfahren zur Charakterisierung und Quantifizierung von anthropogenen Nanopartikeln in der aquatischen Umwelt

Year: 2019
Products: Autosampler
Authors: Dutschke, F;
Journal: Thesis

Manufactured titanium dioxide (TiO2) nanoparticles (TiO2 NPs) are nowadays widely present in products that are accessible to the mass market, such as paints, cosmetics, or sunscreens. Despite the significant increase in their use, the potential effects of these nanoparticles on the environment and biological systems have not been sufficiently studied until now; therefore, reliable analytical methods are required to better characterize these emerging materials. This work uses the hyphenation of inductively coupled plasma-mass spectrometry (ICP-MS) with a separation technique, such as sedimentation field-flow fractionation (SdFFF), to obtain information related to the size and state of agglomeration of the nanoparticles investigated. Initial experiments related to the online coupling of SdFFF with inductively coupled plasmatandem mass spectrometry (ICP-MS/MS) were conducted, allowing the detection and separation of TiO2 NPs. The first step involved the application of the ICP-MS/MS technology using an Ammonia (NH3) mass shift mode, which allows the removal of the different molecular and isobaric interferences that complicate the reliable detection and quantification of titanium (Ti). Under optimized conditions, the achievable instrumental detection limits in matrix solutions were found to be below 10 ng L-1 of Ti. The separation parameters of the SdFFF system were then optimized using NIST SRM 1898, a TiO2 NPs reference material, with nominal sizes of 25 nm. This material is characterized by a hydrodynamic diameter and the state of aggregation; it also uses a multi-angle light scattering (MALS) analysis detector. Moreover, a transmission electron microscopy (TEM) technique was applied to confirm the sizes and shapes of the TiO2 NPs as well as the presence of aggregates.

Links between the phytoplankton community composition and trace metal distribution in summer surface waters of the Atlantic Southern Ocean

Year: 2019
Products: seaFAST-pico SC-4 DX module
Authors: Viljoen, JJ;Weir, I;Fietz, S;Cloete, R;Loock, J;Philibert, R;
Journal: Thesis

This study assessed changes in the phytoplankton community related to macronutrient and bioactive trace metal distribution in surface waters of the Atlantic sector of the Southern Ocean, between Cape Town and Antarctica along the GEOTRACES GIPY_05 (mainly along prime meridian) transect in summer 2014–2015. Several general community structure features were reaffirmed, such as the restriction of cyanobacteria to the northern Subtropical Zone, while haptophytes, such as Phaeocystis, along with diatoms, dominate the community north of the Polar Front, and diatoms clearly dominate south of the Polar Front. These community structure changes were often linked with macro- and micro-nutrient composition changes. For example, the concentration of diatoms increased southwards with the availability of silica whereas the cyanobacterial contribution in the northern Subtropical Zone appeared to be linked with labile cobalt depletion. However, these links were not consistent along the entire transect, i.e., no individual nutrient, such as silica or iron, was linked to community composition changes across all water masses. Each station showed a rather unique combination of nutrient and community compositions. Our findings also indicated impacts on the phytoplankton community through trace metal distributions that could be related to a deep mixing event at ∼54◦S and to ice melt at ∼65 and 68◦S. The timing of sampling after such trace metal fluxes proved to be an important consideration, particularly where iron appeared to be preferentially depleted to near-limiting concentrations, possibly driving utilization of other metals. The study highlights the importance of considering a suite of trace metals when assessing controls of phytoplankton variability in the open ocean and emphasizes the need for higher resolution trace metal sampling and multi-element incubation studies to further study the complex relationships between phytoplankton and nutrients.

Accumulation and Spatial Distribution of Lead and Other Trace Elements in Keratinized Tissues: Investigations Based on Analytical Atomic Spectrometry

Year: 2019
Products: Autosampler
Authors: Tehrani, MW;
Journal: Thesis

Human biomonitoring for toxic metals such as lead (Pb) provides information about absorbed dose from all exposure routes, and is critical for identifying exposed individuals and assessing health risks. Blood Pb and bone Pb are the primary validated biomarkers for assessing short-term and historical Pb exposures, respectively, while non-traditional matrices, including keratinized tissues, can provide complementary exposure information. Hard keratinized tissues – including hair, nails, hooves, and horns – grow incrementally, potentially preserving chemical exposure histories over a span of days to years. Analytical limitations and poor interlaboratory reproducibility, however, have led to debate around the use of human nails and hair in biomonitoring, particularly for Pb. This dissertation addressed several knowledge gaps and analytical challenges relevant to the study of trace element accumulation and distribution in keratinized tissues, with a special focus on Pb. Lead and 16 other elements were measured by atomic mass spectrometry in caprine horns obtained post-mortem from 11 Pb-dosed animals, following cleaning, homogenization, and aciddigestion of each horn. Results for horn Pb displayed a potentially non-linear association with cumulative administered Pb dose, and a significant correlation with absorbed Pb dose as represented by bone Pb measurements. Elemental imaging studies conducted using micro X-ray fluorescence found that Pb is excreted into horns of dosed goats in discrete accumulations or “rings.” While the pattern of these Pb rings did not fully match the dosing history, the data suggested that Pb is eventually excreted into the horn in a manner that reflects the complex recycling of Pb between body compartments after multiple doses.

Spatial assessment of major and trace element concentrations from Lower Athabasca Region Trout-perch (Percopsis omiscomaycus) otoliths

Year: 2019
Products: SC-2 DX
Authors: Sinnatamby, RN;Loewen, TN;Luo, Y;Pearson, DG;Bicalho, B;Grant-Weaver, I;Cuss, CW;Poesch, M;Shotyk, W;
Journal: Sci. Total Environ.

The Lower Athabasca Region (LAR) is home to the largest bitumen deposit in Alberta, and has seen industrial development related to the extraction and processing of bituminous sands since the late 1960s. Along with industrial and economic growth related to oil sands development, environmental concerns have increased in recent decades, including those about potential effects on fish. We measured major and trace element concentrations in Trout-perch otoliths from the Athabasca and Clearwater Rivers in the LAR, to illustrate spatial variations and identify possible industrial impacts. Both laser ablation ICP-MS and solution-based ICP-MS methods were employed. Of the trace elements enriched in bitumen (V, Ni, Mo and Re), only Ni and Re were above the limits of detection using at least one of the methods. The only significant differences in element concentrations between upstream and downstream locations were found for Li, Cu, and Pb which were more abundant upstream of industry. For comparison and additional perspective, otoliths from the same fish species, but taken from the Batchawana River in northern Ontario, were also examined. The fish from Alberta yielded greater concentrations of Ba, Bi, Li, Mg, Na, Re, Sc, Th and Y, but the Ontario fish had more Cr, Rb and Tl, likely because of differences in geology.

Impact of natural re-oxygenation on the sediment dynamics of manganese, iron and phosphorus in a euxinic Baltic Sea basin

Year: 2019
Products: SC-DX SeaFAST S2
Authors: Hermans, M;Lenstra, W;van Helmond, N;Behrends, T;Egger, M;Seguret, M;Gustafsson, E;Gustafsson, B;Slomp, C;
Journal: Geochimica et Cosmochimica Acta

The Baltic Sea is characterized by the largest area of hypoxic (oxygen (O2) < 2 mg L-1) bottom waters in the world’s ocean induced by human activities. Natural ventilation of these O2-depleted waters largely depends on episodic Major Baltic Inflows from the adjacent North Sea. In 2014 and 2015, two such inflows led to a strong rise in O2 and decline in phosphate (HPO42-) in waters below 125 m depth in the Eastern Gotland Basin. This provided the opportunity to assess the impact of such re-oxygenation events on the cycles of manganese (Mn), iron (Fe) and phosphorus (P) in the sediment for the first time. We demonstrate that the re-oxygenation induced the activity of sulphur (S)-oxidising bacteria, known as Beggiatoaceae in the surface sediment where a thin oxic and suboxic layer developed. At the two deepest sites, strong enrichments of total Mn and to a lesser extent Fe oxides and P were observed in this surface layer. A combination of sequential sediment extractions and synchrotron-based X-ray spectroscopy revealed evidence for the abundant presence of P-bearing rhodochrosite and Mn(II) phosphates. In contrast to what is typically assumed, the formation of Fe oxides in the surface sediment was limited. We attribute this lack of Fe oxide formation to the high flux of reductants, such as sulphide, from deeper sediments which allows Fe(II) in the form of FeS to be preserved and restricts the penetration of O2 into the sediment. We estimate that enhanced P sequestration in surface sediments accounts for only ∼5% of water column HPO42- removal in the Eastern Gotland Basin linked to the recent inflows. The remaining HPO42- was transported to adjacent areas in the Baltic Sea. Our results highlight that the benthic O2 demand arising from the accumulation of organic-rich sediments over several decades, the legacy of hypoxia, has major implications for the biogeochemical response of euxinic basins to re-oxygenation. In particular, P sequestration in the sediment in association with Fe oxides is limited. This implies that artificial ventilation projects that aim at removing water column HPO42- and thereby improving water quality in the Baltic Sea will likely not have the desired effect.

Terrestrial sources as the primary delivery mechanism of mercury to the oceans across the Toarcian Oceanic Anoxic Event (Early Jurassic)

Year: 2019
Products: Apex-Q desolvation unit
Authors: Them, T;Jagoe, C;Caruthers, A;Gill, B;Grasby, S;Gröcke, D;Yin, R;Owens, J;
Journal: Earth and Planetary Science Letters

This study evaluates the utility of sedimentary mercury (Hg) contents as a proxy for fingerprinting ancient massive volcanism, which is often associated with biogeochemical perturbations. Herein we present new Hg geochemical data from anoxic marine basins across the Toarcian Oceanic Anoxic Event (T-OAE; ∼183 Ma) as a test of the complex Hg cycle. The T-OAE was likely initiated by the main eruptive phase of the Karoo–Ferrar large igneous province, which caused a subsequent cascade of environmental perturbations and resulting mass extinction. At present the leading interpretation of sedimentary Hg anomalies has been volcanogenic outgassing as the primary source. Our study and compilation results suggest, however, that Hg/TOC anomalies were restricted to shallow-water, and/or proximal environments, while deep-water, more distal depositional settings document no significant Hg-related anomalies. Furthermore, asynchronous stratigraphic deviations in Hg enrichments favor terrestrially sourced materials and local redox variability, rather than direct volcanogenic emissions, as a primary control mechanism. Additionally, Hg isotope signatures from our only study site documenting an Hg anomaly are also consistent with a terrestrial Hg origin during the T-OAE. Therefore, our results suggest that Hg anomalies in the geological record need to be re-evaluated as a “smoking gun” proxy that only infers volcanogenic inputs.

Size exclusion chromatography – Inductively coupled plasma – Mass spectrometry for determining metal-low molecular weight compound complexes in natural wines

Year: 2019
Products: SeaFast SC2 DX autosampler
Authors: Latorre, M;Herbello-Hermelo, P;Peña-Farfal, C;Neira, Y;Bermejo-Barrera, P;Moreda-Piñeiro, A;
Journal: Talanta

Size exclusion chromatography (SEC) hyphenated to inductively coupled plasma – mass spectrometry (ICP-MS), as a specific detector for metals, has been used for monitoring and determining metal-low molecular weight organic compound (LMWC) complexes in natural wines. SEC with UV detection (wavelength of 205 nm) was used for monitoring organic compounds eluted from the chromatographic column. SEC-UV has revealed the presence of low molecular weight compounds (commonly three fractions of molecular weights ranging from 230 to 1579 Da).’ Further experiments using ICP-MS as a detector showed that elements such as B, Cu, Li, Mn, Ni, Ti, and Zn are bound to compounds of molecular weights within the 338–1579 Da range. Total metal concentrations, as well as metal concentrations in SEC fractions were also assessed in several monovarietal red (five varieties) and monovarietal white (three varieties) wines.

Enzymatic hydrolysis as a sample pre-treatment for titanium dioxide nanoparticles assessment in surimi (crab sticks) by single particle ICP-MS

Year: 2019
Products: SeaFast SC2 DX autosampler
Authors: Taboada-López, M;Herbello-Hermelo, P;Domínguez-González, R;Bermejo-Barrera, P;Moreda-Piñeiro, A;
Journal: Talanta

A reliable sample pre-treatment based on enzymatic hydrolysis has been fully optimized and validated for TiO2 NPs isolation and determination/characterization in surimi (crab sticks). Efficient extractions have been found when using a pancreatin/lipase mixture at pH 7.4 and 37 °C for 12 h under continuous stirring. The proposed sample pre-treatment procedure has been found not to change TiO2 NPs size distribution, therefore guaranteeing TiO2 NPs integrity. TiO2 NPs determination (TiO2 NPs concentration) and TiO2 NPs characterization (size distribution) were assessed by single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) working with dwell times in the microsecond range (high frequency of data acquisition). Method validation was performed for TiO2 NPs concentrations and TiO2 NPs sizes. Good repeatability (25% and 8% for TiO2 NPs concentration and TiO2 NPs most frequent size), and sensitivity (limit of detection of 5.28 × 105 NPs g−1for TiO2 NPs concentrations, and 31.3–37.1 nm for TiO2 NPs size) were obtained. Accuracy, calculated through analytical recovery was adequate. Recoveries for TiO2 NPs standards of 50 and 100 nm were 108 ± 5 and 105 ± 4%, respectively. The proposed methodology was applied to several surimi samples for assessing TiO2 NPs concentrations and size distribution. Some surimi samples were found to contain TiO2 NPs (concentrations from 1.40 × 107 to 1.19 × 109 NPs g−1). TiO2 NPs size distributions were very different among the samples, and some of them showed wide size ranges (the most frequent size varied from 53.8 to 62.1 nm; whereas, the mean size values were within the 73.4–217.5 nm range).

Metabolism and disposition of arsenic species from oral dosing with sodium arsenite in neonatal CD-1 mice. IV. Toxicokinetics following gavage administration and lactational transfer

Year: 2019
Products: PC3
Authors: Twaddle, NC;Vanlandingham, M;Beland, FA;Fisher, JW;Doerge, DR;
Journal: Food Chem. Toxicol.

Arsenic is a ubiquitous contaminant, with typical human dietary intake below 1 μg/kg bw/d and extreme drinking water exposures up to ∼50 μg/kg bw/d. The formation and binding of trivalent metabolites are central to arsenic toxicity and strong human evidence suggests special concern for early life exposures in the etiology of adult diseases, especially cancer. This study measured the metabolism and disposition of arsenite in neonatal mice to understand the role of maturation in metabolic activation and detoxification of arsenic. Many age-related differences were observed after gavage administration of arsenite, with consistent evidence in blood and tissues for higher exposures to trivalent arsenic species in neonatal mice related to the immaturity of metabolic and/or excretory functions. The evidence for greater tissue binding of arsenic species in young mice is consistent with enhanced susceptibility to toxicity based on metabolic and toxicokinetic differences alone. Lactational transfer from arsenite-dosed dams to suckling mice was minimal, based on no dosing-related changes in the levels of arsenic species in pup blood or milk collected from the dams. Animal models evaluating whole-life exposure to inorganic arsenic must use direct dosing in early neonatal life to predict accurately potential toxicity from early life exposures in children.

A common parentage-low abundance trace element data of gem diamonds reveals similar fluids to fibrous diamonds

Year: 2019
Products: APEX-Q high-efficiency sample introduction system
Authors: Krebs, M;Pearson, D;Stachel, T;Laiginhas, F;Woodland, S;Chinn, I;Kong, J;
Journal: Lithos

Quantitative trace element data from high-purity gem diamonds from the Victor Mine, Ontario, Canada as well as near-gem diamonds from peridotite and eclogite xenoliths from the Finsch and Newlands mines, South Africa, acquired using an off-line laser ablation method show that we see the same spectrum of fluids in both high-purity gem and near-gem diamonds that was previously documented in fibrous diamonds. “Planed” and “ribbed” trace element patterns characterize not only the high-density fluid (HDF) inclusions in fibrous diamonds but also in gem diamonds. Two diamonds from two Finsch harzburgite xenoliths show trace element patterns similar to those of saline fluids, documenting the involvement of saline fluids in the precipitation of gem diamonds, further strengthening the link between the parental fluids of both gem and fibrous diamonds. Differences in trace element characteristics are evident between Victor diamonds containing silicate inclusions compared with Victor diamonds containing sulphide inclusions. The sulphide-bearing diamonds show lower levels of inter-element fractionation and more widely varying siderophile element concentrations - indicating that the silicate and sulphide-bearing diamonds likely formed by gradations of the same processes, via melt-rock reaction or from a subtly different fluid source. The shallow negative LREEN-HREEN slopes displayed by the Victor diamonds establish a signature indicative of original derivation of the diamond forming agent during major melting (~10% melt). Consequently, this signature must have been passed on to HDFs separating from such silicate melts.

High-resolution Sr-isotopic evolution of Black Sea water during the Holocene: Implications for reconnection with the global ocean

Year: 2019
Products: ESI SC-2 autosampler
Authors: Ankindinova, O;Hiscott, R;Aksu, A;Grimes, V;
Journal: Marine Geology

The 10 m-thick Holocene succession at core site M02-45 (41°41.17′N, 28°19.08′E, −69 m water depth) has key advantages for investigation of the Sr-isotopic evolution of the Holocene Black Sea. Earlier studies have focussed on thinner successions and coquinas. At the M02-45 site (augmented by nearby core M05-03P), 87Sr/86Sr determinations on mollusc shells extracted at mostly 10–20 cm depth increments provide a temporal resolution mostly <200 years in sediment older than ~5500 cal yr BP, and ~20–25 years for the early Holocene reconnection between the Black Sea (formerly the Neoeuxine Lake) and the global ocean. Isotopic measurements are in stratigraphic order, so temporal trends are unambiguous. Measurements were made using a Neptune multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) and have 1σ uncertainties of ~ ±0.000015. There are four stages of 87Sr/86Sr increase and salination associated with the reconnection. From 12,145–9580 cal yr BP (stage A), before first Mediterranean inflow, the Sr-isotopic ratio varied from 0.708847–0.708881. Modelling suggests that the Sr concentration in the Neoeuxine Lake might have been several times higher than modern river values because of evaporative concentration. For ~100 years immediately before reconnection (9580–9490 cal yr BP, stage B), 87Sr/86Sr values dropped to their lowest levels: 0.708841–0.708843. Abruptly (in geological terms), 87Sr/86Sr then began to climb starting 9465–9490 cal yr BP and reached a quasi-steady-state ‘plateau’ with ratios ~0.708965 by ~9380 cal yr BP (stage C). The sharp 87Sr/86Sr increase marks the first significant intrusion of saline water into a previously isolated Neoeuxine Lake. The quasi-steady-state condition lasted 350–400 years. Subsequently, starting ~8985 cal yr BP and proceeding to the present day, there was a step-wise rise of 87Sr/86Sr to modern levels (stage D), during which a salinity threshold was passed that allowed widespread replacement of brackish-water faunas by Mediterranean species. Modelling suggests that the lake/sea level likely did not, and could not, rise from −120 m to −30 m between 9490 and 9380 cal yr BP unless (a) the Sr concentration in the pre-reconnection Neoeuxine Lake was 3–4 times higher than today, or (b) the water column was strongly stratified during first entry of saline water. The second alternative is very unlikely because of seasonal vertical mixing (downwelling/upwelling) in what was then a rather homogeneous temperate lake. Catastrophic flooding of a lowstand lake would require an average discharge through the Strait of Bosphorus of ~9500 m3 s−1, whereas saline entry of Mediterranean water as an underflow into an already high lake could reproduce the first stage of 87Sr/86Sr increase with an average discharge as low as ~2200 m3 s−1. Because the M02-45 site is ~50 m above the late Pleistocene lowstand shoreline and contains sub-wavebase sediments with 87Sr/86Sr values that record the first entry of saline water into the Neoeuxine Lake, the surface of the lake must have been significantly higher than −70 m at the time of the reconnection. Two prominent ‘plateaux’ which punctuate the long-term 87Sr/86Sr increase are attributed to decadal to centennial periods of increased discharge from European rivers, creating a positive hydrological balance and effectively blocking or seriously impeding saline-water advance up the Strait of Bosphorus toward the Black Sea.

Single particle mineralogy of microparticles from Himalayan ice-cores using SEM/EDX and ATR-FTIR imaging techniques for identification of volcanic ash signatures

Year: 2019
Products: Apex HF
Authors: Malek, M;Eom, H;Hwang, H;Hur, S;Hong, S;Hou, S;Ro, C;
Journal: Chemical Geology

In this study, insoluble microparticles from four discrete layers of ice-cores drilled out from the East Rongbuk glacier of the Himalayas were characterized on a single particle basis by scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM/EDX) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) imaging. The combined application of the two single particle analytical techniques for the analysis of the same individual particles provided complementary information, i.e., their elemental compositions and morphology by SEM/EDX and their molecular species, functional groups, and crystallinity by ATR-FTIR imaging, which is crucial for the definite identification of the mineral species including their polymorphs. The results showed that the integrated signatures of volcanic ash (VA), involving their mineralogical characteristics for silica polymorphs, vitreous nature of silica and silicate particles, chemical heterogeneity within the micrometer sized particles, and unique morphology, can be used to clearly differentiate micrometer sized VA from the mineral dust of a soil origin on a single-particle basis. The different mineralogical characteristics among the volcanic samples would be due to their association with different volcanic eruptions.

Matrix separation of Sr and Pb for isotopic ratio analysis of Ca-rich samples via an automated simultaneous separation procedure

Year: 2019
Products: prepFAST-MC™
Authors: Zimmermann, T;Retzmann, A;Schober, M;Pröfrock, D;Prohaska, T;Irrgeher, J;
Journal: Spectrochimica Acta Part B: Atomic Spectroscopy

This paper presents a systematic investigation of the effects of Ca on the matrix separation of Sr and Pb and subsequent isotope-amount ratio measurements using a variety of synthetic solutions and reference materials with varying Ca content during the application of an automated analyte/matrix separation approach. The separation method based on the DGA Resin was optimized by using increased column bed volumes, comparing two different column sizes (1-mL and 3-mL-bed volume). Certified reference materials (synthetic calcium carbonate – MACS-3, basalt – BCR-2, saggital otolith – FEBS-1, bone meal – NIST SRM 1486, bone ash – NIST SRM 1400, and skim milk powder – BCR-063R) with varying Ca content, Ca/Sr and Ca/Pb mass fraction ratios were separated using the optimized method and analyzed for the Sr and Pb isotopic composition by multi collector inductively coupled plasma mass spectrometry (MC ICP-MS). The developed separation method based on the 3-mL-bed volume column provides quantitative recoveries (84% to 105% for Sr, 77% to 96% for Pb), while maintaining a quantitative separation of Sr and Pb. Procedural blank levels were < 0.04 ng g−1 for Sr and < 0.05 ng g−1 for Pb, respectively. The method allows for the automated extraction of Sr in Ca-rich matrices with Ca/Sr mass fraction ratios of up to 4051 corresponding to an absolute Ca load of 965 μg ± 86 μg (BCR-063R, milk powder). Furthermore, the method allows for the simultaneous extraction of Pb from these matrices showing Ca/Pb mass fraction ratios of up to 42,095 corresponding to an absolute Ca load of 761 μg ± 122 μg on column (NIST SRM 1400, bone tissue), respectively. This results in at least 5-times higher tolerable Ca loads compared to previous methods. Measured δ(87Sr/86Sr)NIST SRM 987 values of FEBS-1 (−1.58 ‰ ± 0.23 ‰ (U, k = 2)), MACS-3 (−4.11 ‰ ± 0.29 ‰ (U, k = 2)) and NIST SRM 1400 (3.87 ‰ ± 0.23 ‰ (U, k = 2)) were in accordance with published results. Measured δ(208Pb/206Pb)NIST SRM 981 (−29.87 ‰ ± 0.07 ‰ (U, k = 2)), δ(207Pb/206Pb)NIST SRM 981 (−66.95 ‰ ± 0.17 ‰ (U, k = 2)) and δ(208Pb/204Pb)NIST SRM 981 (51.55 ‰ ± 0.26 ‰ (U, k = 2)) values of NIST SRM 1400 were also in accordance with published results. Furthermore, we propose a n(87Sr)/n(86Sr) isotope-amount ratio of 0.70884 ± 0.00017 (U, k = 2) corresponding to a δ(87Sr/86Sr)NIST SRM 987 value of −2.11 ‰ ± 0.24 ‰ (U, k = 2) for the BCR-063R reference material. Additionally, we propose a n(208Pb)/n(206Pb) isotope-amount ratio of 2.0793 ± 0.0001 (U, k = 2) corresponding to a δ(208Pb/206Pb)NIST SRM 981 of −40.97 ‰ ± 0.05 ‰ (U, k = 2), a n(207Pb)/n(206Pb) isotope-amount ratio of 0.84995 ± 0.00008 (U, k = 2) corresponding to a δ(207Pb/206Pb)NIST SRM 981 of −70.72 ‰ ± 0.09 ‰ (U, k = 2) and a n(208Pb)/n(204Pb) isotope-amount ratio of 38.221 ± 0.008 (U, k = 2) corresponding to a δ(208Pb/204Pb)NIST SRM 981 of 40.82 ‰ ± 0.23 ‰ (U, k = 2) for the reference material MACS-3.

LA-ICP-MS/MS improves limits of detection in elemental bioimaging of gadolinium deposition originating from MRI contrast agents in skin and brain tissues

Year: 2019
Products: MicroMist concentric nebuliser
Authors: Clases, D;Fingerhut, S;Jeibmann, A;Sperling, M;Doble, P;Karst, U;
Journal: J Trace Elem Med Biol

A novel analytical method to detect the retention of gadolinium from contrast agents for magnetic resonance imaging (MRI) in tissue samples of patients is presented. It is based on laser ablation - inductively coupled plasma - triple quadrupole - mass spectrometry (LA-ICP-MS/MS). Both Gd and P were monitored with a mass shift of +16, corresponding to mono-oxygenated species, as well as Zn, Ca, and Fe on-mass. This method resulted in a significantly reduced background and improved limits of detection not only for phosphorus, but also for gadolinium. These improvements were essential to perform elemental bioimaging with improved resolution of 5 μm x 5 μm, allowing the detection of small Gd deposits in fibrotic skin and brain tumour tissue with diameters of approximately 50 μm. Detailed analyses of these regions revealed that most Gd was accompanied with P and Ca, indicating co-precipitation.

Association between catatonia and levels of hair and serum trace elements and minerals in autism spectrum disorder

Year: 2019
Products: ESI SC-2 DX4 autosampler
Authors: Tinkov, AA;Skalnaya, MG;Simashkova, NV;Klyushnik, TP;Skalnaya, AA;Bjørklund, G;Notova, SV;Kiyaeva, EV;Skalny, AV;
Journal: Biomed. Pharmacother.

The objective of the study was to investigate the association between catatonia in autism spectrum disorder (ASD) and the levels of hair and serum trace elements and minerals in children with ASD. The levels of hair and serum trace elements and minerals of boys suffering from ASD with (n = 30) and without (n = 30) catatonia, as well as 30 age- and sex-matched neurotypical controls were assessed using ICP-MS. Hair calcium (Ca) and selenium (Se) levels were lower in ASD patients as compared to the controls. Hair mercury (Hg) levels in ASD patients were more than 3-fold and 2-fold higher as compared to the controls and children with catatonia in ASD. Hair iodine (I) and manganese (Mn) were the lowest and the highest in ASD + Catatonia, respectively. Serum aluminium (Al) and cadmium (Cd) levels in healthy controls were significantly higher in comparison to the patients of both groups. Serum chromium (Cr), copper (Cu) levels were significantly increased in patients with ASD and catatonia, whereas vanadium (V) levels were elevated in patients both with and without catatonia. Multiple regression analysis demonstrated that hair Hg and serum Al and Cd levels were negatively associated with catatonia in ASD in crude and adjusted models. Although the etiology of catatonia in ASD is unclear, the obtained data demonstrate that catatonic symptoms in ASD may be at least partially mediated by altered trace element levels. Further studies are required to elucidate the role of trace elements in the potential signaling mechanisms of catatonia.

Speciation of zinc in fish feed by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry - using fractional factorial design for method optimisation and mild extraction conditions

Year: 2019
Products: FAST SC-4Q DX
Authors: Silva, MS;Sele, V;Sloth, JJ;Araujo, P;Amlund, H;
Journal: J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.

Zinc (Zn) is an element essential to all living organisms and it has an important role as a cofactor of several enzymes. In fish, Zn deficiency has been associated with impaired growth, cataracts, skeletal abnormalities and reduced activity of various Zn metalloenzymes. Fish meal and fish oil traditionally used in salmon feed preparation are being replaced by plant-based ingredients. Zinc additives are supplemented to salmon feed to ensure adequate Zn levels, promoting good health and welfare in Atlantic salmon (Salmo salar). The main objective of the present study was to evaluate Zn species found in an Atlantic salmon feed. This work describes a Zn extraction method that was optimized using a fractional factorial design (FFD), whereby the effect of six factors could be studied by performing only eight experiments. The effects of the type of extraction solution and its molar concentration, pH, presence of sodium dodecyl sulphate, temperature and extraction time on Zn extraction were investigated. Mild extraction conditions were chosen in order to keep the Zn species intact. Total Zn (soluble fractions and non-soluble fractions) was determined by inductively coupled plasma mass spectrometry (ICP-MS). The highest Zn recovery was obtained using 100 mM Tris-HCl, pH 8.5 at a temperature of 4 °C for 24 h where the total Zn in soluble fraction and non-soluble fraction was 9.9 ± 0.2% and 98 ± 6%, respectively. Zinc speciation analysis (on the soluble fractions) was further conducted by size exclusion inductively coupled plasma mass spectroscopy (SEC-ICP-MS). The SEC-ICP-MS method provided qualitative and semi-quantitative information regarding Zn species present in the soluble fractions of the feed. Four Zn-containing peaks were found, each with different molecular weights: Peak 1 (high molecular weight - ≥600 kDa), peak 2 and peak 3 (medium molecular weight - 32 to 17 kDa) were the least abundant (1-6%), while peak 4 (low molecular weight - 17 to 1.36 kDa) was the most abundant (84-95%).

An evaluation of Rb-Sr isotope dilution analyses with a 86Sr-enriched tracer and Multiple Collection-ICP-MS

Year: 2019
Products: Apex IR
Authors: Beranoaguirre, A;Pin, C;Sanchez-Lorda, M;García de Madinabeitia, S;Gil Ibarguchi, J;
Journal: International Journal of Mass Spectrometry

A straightforward method is described allowing to determine on a routine basis Rb and Sr concentrations and 87Rb/86Sr isotope by using the isotope dilution method with isotopic tracers enriched in 87Rb and in 86Sr, respectively, and MC-ICP-MS for mass spectrometric measurements. The 87Sr/86Sr isotope ratios are measured separately on unspiked sample aliquots, thereby alleviating the need for correcting the contribution that would arise in case of total spiking with an 84Sr enriched tracer. The sample preparation involves sample dissolution with hydrofluoric acid, and the separation of Rb and Sr from matrix elements and from each other by combining extraction chromatography and cation exchange in nitric acid medium. The concentration and 87Rb/86Sr data measured on replicate dissolutions of several international geostandards display the very good reproducibility typical of the isotope dilution method, even at low analyte concentration. The within-run precisions of 87Sr/86Sr isotope ratios (2 S.E. from 1 10−5 to 3 10-5) are not as good as those typically achieved by TIMS, but the data show a good reproducibility (0.002% RSD) and are accurate, based on their fair agreement with recommended values. However, these figures are significantly worse at low Sr concentration, indicating that 87Sr/86Sr ratios should preferably be measured by TIMS when Sr-poor samples are processed.

Mesoscale variability related to iron speciation in a coastal Ross Sea area (Antarctica) during summer 2014

Year: 2019
Products: PFA-ST microne- bulizer
Authors: Rivaro, P;Ardini, F;Grotti, M;Aulicino, G;Cotroneo, Y;Fusco, G;Mangoni, O;Bolinesi, F;Saggiomo, M;Celussi, M;
Journal: Chemistry and Ecology

Dissolved iron (Fe) distribution and speciation was determined in water samples (0–200 m) collected in a coastal area near Terra Nova Bay during the austral summer of 2014. Nutrients, dissolved oxygen, chlorophyll-a, phytoplankton composition and prokaryotic biomass distribution were investigated in combination with measurements of the physical properties of the water columns and its dynamics. The dFe value was above the limiting growth concentration, ranging from 0.52 to 4.51 nM, and it showed a spatial variability with a horizontal length scale of about 10 km, according to the variability of the water column physical properties and to iron sources. The organic ligands (L) maintained the concentrations of dFe at levels much higher than the inorganic solubility of Fe, keeping it available for phytoplankton and the log K’FeL values found (from 22.1 to 23.6) highlighted the presence of complexes of differing stabilities.

Reproducible automated renewable column generation

Year: 2019
Products: prepFAST MC
Authors: Shalina C. Metzger,Brian W. Ticknor,Kayron N. Tevepaugh,Debra A. Bostick,Eddy H. McBay,M. Paul Field,Hwan Kim & Cole R. Hexel
Journal: Separation Science and Technology

Preparation of chromatographic columns requires considerable time during chemical separation procedures. Automated systems capable of repeatedly generating renewable, uniformly packed columns would find widespread use in analytical laboratories. Here, a fully automated commercial-off-the-shelf (COTS) system was utilized to pack and unpack 1 mL TEVA and UTEVA columns. To accurately determine the reproducibility of the resin load per column, studies were conducted over several weeks. Method optimization yielded an improvement in loading from 15–19% to 3–5% relative standard deviation. Availability of automated COTS equipment capable of reproducibly generating separation columns has the potential to reduce time and costs associated with column separation.

Evaluation and Specifications for In-Line Uranium Separations Using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) Detection for Trace Elemental Analysis

Year: 2019
Products: prepFAST IC
Authors: Benjamin T. Manard, Shalina C. Metzger , C. Derrick Quarles Jr., Kayron T. Rogers, Brian W. Ticknor, Debra A. Bostick, Eddy H. McBay, and Cole R. Hexel
Journal: Applied Spectroscopy

Automated introduction platforms integrated with inductively coupled plasma optical emission spectroscopy (ICP-OES) systems are continuously being improved. Expanding on the introduction systems, a newly developed automated ion chromatography system was explored for performing rapid in-line separations coupled to ICP-OES for the detection of trace elements in uranium. Trace elements are separated from a uranium material and the analytes are directed into the ICP-OES for subsequent detection. Detection parameters such as exposure time frequency, wavelength selection, and settling times were explored to gain insight on optimal detection schemes for in-line trace elemental analysis. The methodology was applied in the analysis of a uranium oxide (U3O8) certified reference material, CRM-124. It was found here that the sensitivity and uncertainty of the technique are greatly affected by how the ICP-OES is employed to collect data. Overall it was determined that faster exposure replicates can provide greater peak resolution with higher fidelity measurements but are limited with respect to the total analysis time (i.e., limited in detection timely separations). Zeta scores, which combine accuracy and uncertainty of certified values and experimental values, were used to validate the ICP-OES modes of operation.

Fully oxygenated water columns over continental shelves before the Great Oxidation Event

Year: 2019
Products: Apex inlet system
Authors: Ostrander, CM;Nielsen, SG;Owens, JD;Kendall, B;Gordon, GW;Romaniello, SJ;Anbar, AD;
Journal: Nat Geosci

Late Archaean sedimentary rocks contain compelling geochemical evidence for episodic accumulation of dissolved oxygen in the oceans along continental margins before the Great Oxidation Event. However, the extent of this oxygenation remains poorly constrained. Here we present thallium and molybdenum isotope compositions for anoxic organic-rich shales of the 2.5 billion-year-old Mount McRae Shale from Western Australia, which previously yielded geochemical evidence of a transient oxygenation event. During this event, we observe an anti-correlation between thalium and molybdenum isotope data, including two shifts to higher molybdenum and lower thalium isotope compositions. Our data indicate pronounced burial of manganese oxides in sediments elsewhere in the ocean at these times, which requires that water columns above portions of the ocean floor were fully oxygenated: all the way from the air-sea interface to well below the sediment-water interface. Well-oxygenated continental shelves were likely the most important sites of manganese oxide burial and mass-balance modeling results suggest that fully oxygenated water columns were at least a regional-scale feature of early-Earth's oceans 2.5 billion years ago.

Revisiting the distribution of oceanic N2 fixation and estimating diazotrophic contribution to marine production

Year: 2019
Products: SeaFASTpico introduction system
Authors: Tang, W;Wang, S;Fonseca-Batista, D;Dehairs, F;Gifford, S;Gonzalez, AG;Gallinari, M;Planquette, H;Sarthou, G;Cassar, N;
Journal: Nat Commun

Marine N2 fixation supports a significant portion of oceanic primary production by making N2 bioavailable to planktonic communities, in the process influencing atmosphere-ocean carbon fluxes and our global climate. However, the geographical distribution and controlling factors of marine N2 fixation remain elusive largely due to sparse observations. Here we present unprecedented high-resolution underway N2 fixation estimates across over 6000 kilometers of the western North Atlantic. Unexpectedly, we find increasing N2 fixation rates from the oligotrophic Sargasso Sea to North America coastal waters, driven primarily by cyanobacterial diazotrophs. N2 fixation is best correlated to phosphorus availability and chlorophyll-a concentration. Globally, intense N2 fixation activity in the coastal oceans is validated by a meta-analysis of published observations and we estimate the annual coastal N2 fixation flux to be 16.7 Tg N. This study broadens the biogeography of N2 fixation, highlights the interplay of regulating factors, and reveals thriving diazotrophic communities in coastal waters with potential significance to the global nitrogen and carbon cycles.

Reconstruction of Atlantic herring (Clupea harengus) recruitment in the North Sea for the past 455 years based on the δ13C from annual shell increments of the ocean quahog (Arctica islandica)

Year: 2019
Products: Elemental Scientific micromill system
Authors: Estrella-Martínez, J;Schöne, B;Thurstan, R;Capuzzo, E;Scourse, J;Butler, P;
Journal: Fish and Fisheries

Understanding the recruitment variability of the Atlantic herring North Sea stock remains a key objective of stock assessment and management. Although many efforts have been undertaken linking climatic and stock dynamic factors to herring recruitment, no major attempt has been made to estimate recruitment levels before the 20th century. Here, we present a novel annually resolved, absolutely dated herring recruitment reconstruction, derived from stable carbon isotope geochemistry (δ13C), from ocean quahog shells from the Fladen Ground (northern North Sea). Our age model is based on a growth increment chronology obtained from fourteen shells. Ten of these were micromilled at annual resolution for δ13C analysis. Our results indicate that the anthropogenically driven relative depletion of 13C, the oceanic Suess effect (oSE), became evident in the northern North Sea in the 1850s. We calculated a regression line between the oSE‐detrended δ13C results (δ13CṠ) and diatom abundance in the North Sea, the regression being mediated by the effect of phytoplankton on the δ13C of the ambient dissolved inorganic carbon. We used this regression to build an equation mediated by a nutritional link to reconstruct herring recruitment using δ13CṠ. The reconstruction suggests that there were five extended episodes of low‐recruitment levels before the 20th century. These results are supported by measured recruitment estimates and historical fish catch and export documentation. This work demonstrates that molluscan sclerochronological records can contribute to the investigation of ecological baselines and ecosystem functioning impacted by anthropogenic activity with implications for conservation and stock management.


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