Ultra-trace element characterization of the central Ottawa River basin using a rapid, flexible, and low-volume ICP-MS method

Ultra-trace (<1 ng g-1) rare earth elements and yttrium (REE+Y) and high field strength element (HFSE) geochemistry of freshwater can constrain element sources, aqueous processes in hydrologic catchments, and the signature of dissolved terrestrial fluxes to the oceans. This study details an adapted method capable of quantifying ≥38 elements (including all REE+Y, Nb, Ta, Zr, Hf, Mo, W, Th, U) with minimal sample preparation in natural water aliquots as low as ≤2 mL. The method precision and accuracy are demonstrated using measurement of the National Research Council – Conseil national de recherches Canada (NRC-CNRC) river water certified reference material (CRM) SLRS-6 sampled from the Ottawa River (OR). Data from SLRS CRM are compared to those of new, filtered (HREE-enriched REE+Y patterns, small natural positive Y and Gd anomalies, and negative Eu and Ce anomalies. These REE+Y features are coherent downstream in the OR apart from amplification of Eu and Ce anomalies during REE removal/dilution. The OR samples capture a downstream decrease in sparingly soluble HFSE (Th, Nb, Ta, Zr, Hf), presumably related to their colloid-particulate removal from the dissolved load, accompanied by crustal Zr/Hf (32.5 ± 5.1) and supercrustal Nb/Ta (25.1 ± 7.7) ratios. Subcrustal Th/U (0.17-0.96) and supercrustal Mo/W (12.0-74.5) ratios in all ORB waters indicate preferential release and aqueous solubility of U>Th and Mo>W, with the latter attributed primarily to preferential W adsorption on soil or upstream aquatic (oxy)(hydr)oxide surfaces

Trace element and Pb isotope fingerprinting of atmospheric pollution sources: A case study from the east coast of Ireland

Unravelling inputs of multiple air pollution sources and reconstructing their historic contribution can be a difficult task. Here, new trace metal concentrations and Pb isotope data were combined for a radionuclide (210Pb-241Am) dated peat core from the Liffey Head bog (LHB) in eastern Ireland in order to reconstruct how different sources contributed to the atmospheric pollution over the past century. Highest enrichments in the heavy metals Pb, Cu, Ag, Sn, and Sb, together with a Pb isotope composition (206Pb/204Pb: 18.351 ± 0.013; 206Pb/207Pb: 1.174 ± 0.012) close to that of the Wicklow mineralisation demonstrates significant aerial influx of heavy metals from local mining and smelting activities during the 19th century until ca. 1940s. A dramatic compositional shift defined by elevated Co, Cr, Ni, Mo, Zn, and V enrichments and a sharp transition towards unradiogenic 206Pb values (206Pb/204Pb: 18.271 ± 0.013–17.678 ± 0.006; 206Pb/207Pb: 1.170 ± 0.012–1.135 ± 0.007) is documented from the 1940s until ca. 2000. These are attributed to the atmospheric impact of fossil fuels and especially leaded petrol, modelled to have contributed between 6 and 78% to the total Pb pollution at this site. The subsequent turn to a more radiogenic Pb isotope signature since 2000 in Ireland is clearly documented in the investigated archive (206Pb/204Pb: 17.930 ± 0.006; 206Pb/207Pb: 1.148 ± 0.007) and reflects the abolishment of leaded petrol. However, there remains a persisting and even increasing pollution in Ni, Mo, Cu, and especially Zn, collectively originating from countrywide use of fossil fuels(peat, coal, heating oil, and unleaded vehicle fuels) for domestic and industrial purposes. This illustrates the continued anthropogenic influence on important natural archives such as bogs in Ireland despite the phase-out of leaded petrol

Real-time investigation of skin blood flow changes induced by topical capsaicin

Capsaicin induces a localized inflammatory process known as neurogenic inflammation upon its topical administration on the skin, due to the release of various neuropeptides from the cutaneous sensory nerve endings. In this study, we investigated real-time skin blood flow changes that occur in neurogenic inflammation induced by topical capsaicin by means of in vivo reflectance confocal microscopy. 27 healthy subjects (15 women and 12 men, mean age ± Standard Deviation: 22.62±4.47) were administered topical capsaicin solution (Capsaicin group) or immersion oil (Control group) on the dorsal side of their non-dominant hand. At different time intervals during administration (0, 10, 25, and 40 minutes), cutaneous blood flow was evaluated using reflectance confocal microscopy and compared between the two groups. Blood flow values were higher during topical capsaicin, with significant increase after 25 (P=0.0160, Dunn’s multiple comparisons test) and 40 minutes (P=0.0132, Dunn’s multiple comparisons test) after its administration when compared with the initial 0 min value. Furthermore, the differences in the blood flow changes between the two groups were significant at 25 min (P=0.0182, Dunn’s multiple comparisons test) and 40 min (P=0.0296, Dunn’s multiple comparisons test) after capsaicin administration. Reflectance confocal microscopy allows in vivo, real-time evaluation of cutaneous blood flow changes within the capsaicin-induced inflammation, and this method might serve as a research model to test neurovascular reactivity. </p

Peat bogs as archives of atmospheric metal pollution from natural and anthropogenic sources - A case study from Ireland

This research project combines various geochemical techniques to identify and characterise historic and recent sources of atmospheric metal pollution recorded in ombrotrophic peat bogs across Ireland. In a first subproject, trace element concentrations and Pb isotope signatures are used to investigate a peat monolith from the Liffey Head bog in the Wicklow Mountains (Co. Wicklow, eastern Ireland). The results show significant heavy metal (Cu, Zn, Pb, Ag, Sb, Sn, Cd) perturbance during the local Pb-Zn mining and smelting activities (19th-20th century), with concentrations exceeding crustal abundances by far (e.g., 40-fold Pb, 80-fold Sb). Lead isotopes display the composition of the local lithology during the mining period of the 19th century (206Pb/207Pb=1.183?0.013) but shift towards significantly less radiogenic values (206Pb/207Pb=1.138?0.011) in 1980, reflecting the wider use of leaded petrol in the northern hemisphere. Remarkably, the highest Pb pollution at this site is not associated with the use of leaded petrol rather than the historic metalliferous activity in the Wicklow uplands. In the second subproject, evolution and sources of recent atmospheric metal pollution with emphasis on Zn are examined and compared in a near-urban environment (Liffey Head bog, Co. Wicklow, east coast) and a rural area (Brackloon wood, Co. Mayo, west coast of Ireland). A combination of trace metal systematics, radiogenic Pb- and stable Zn isotopes allows to distinguish pollution sources. A dominant influence from solid fossil fuel combustion (coal) can be inferred for west Ireland (Cr/Cd=12, Zn/Cd=96, at 0-1 cm) whereas increasing emissions from the wider deployment of liquid fossil fuels (oil, diesel, petrol) are recorded close to the urban area of Dublin in east Ireland (oil: Cu/Cd=57, Zn/Cd=300 at 0-1 cm). This interpretation is further supported by increasingly light Zn isotope signatures with sallower peat bog horizons (?66Zn/64Zn= from 0.53 to 0.18 ?0.03?), readily explained by stronger traffic emissions through recent time. In a third subproject, the geochemical record of the historic Laki 1783-4 volcanic eruption was identified and further examined in Brackloon wood peat bog horizons from western Ireland. This eruption record is expressed in excess metal concentrations of V, Ti, and Fe. Although these cannot unequivocally be attributed to an addition of basaltic cryptotephra at this depth, the higher concentrations of these elements in the separately investigated tephra shards compared to background peat support this hypothesis. Moreover, remarkably systematic correlations are observed for metal ratios such as Cu/Cd, Pb/Cd, Pb/Zn, Cu/Zn between the tephra-bearing layer and Laki aerosols previously detected in Greenland ice. These correlations point to a common volcanic aerosol signal originating from the Laki eruption. Although the high background in the peat monolith complicates a deconvolution of the S signal, subtle S enrichments at the depth of tephra deposition are attributed to addition of Laki 1783-4 volcanic aerosols. Altogether, the potential of peat bog archives to record volcanogenic metal deposition is demonstrated and dependent on background concentration levels