| 1. |
- Barregård, Lars, 1948, et al.
(author)
-
Normal variability of 22 elements in 24-hour urine samples - Results from a biobank from healthy non-smoking adults.
- 2021
-
In: International journal of hygiene and environmental health. - : Elsevier BV. - 1618-131X .- 1438-4639. ; 233
-
Journal article (peer-reviewed)abstract
- Urine is often used for biomonitoring the exposure to elements. However, most studies report concentrations in spot urine samples, which may not accurately mirror the "gold standard" of complete 24-h (24h) urine samples. There are relatively few data published for 24h samples, and little information on the within- and between person variability.The present study aimed at assessing variability within and between individuals in 24h excretion for a number of elements in adults from the general population and the typical 24h excretion of these elements. In addition, we assessed concentrations adjusted for creatinine and specific gravity (SG), and associations between elements.60 healthy non-smokers (31 women and 29 men) from Sweden, aged 21-64 years, collected all urine during 24h (split into six separate samples) on two occasions, about one week apart. Concentrations of As, Br, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, P, Pb, S, Sb, Se, Sn, U, V, W, and Zn in urine were analyzed by inductively coupled plasma sector-field mass spectrometry (ICP-SF-MS) and 24h excretion rates were calculated for each day. The ratio of between-individual variance and the total variance, the intra-class correlation (ICC) was calculated based on natural log-transformed 24h excretion. Correlation coefficients were calculated between excretion rates (mass/24h), and concentrations adjusted for creatinine and SG.Geometric means (GM), and 90-percentiles are presented for each element. The 24h excretion was higher in men than in women for most elements, and the difference was statistically significant for Cr, Cu, Fe, Li, P, Pb, S, Se, U, V, and Zn. However, for Cd and Co, the excretion was higher in women. Variability between days was low for Cd, Co, Hg, Pb, Sn, Se, V, and Zn (ICC 0.75-0.90), highest for Cr (ICC=0.3) and Sb (ICC=0.18), and moderate for the other elements. Spearman's rank correlation coefficients were about 0.8-0.9 for 17 elements, and 0.3-0.7 for Br, Cu, P, S, Se. Excretion of P and S were highly correlated, and also associated with excretion of most of the other elements, especially Cu, Se, V, and Zn. A high correlation was also found between As and Hg, between Mo and W, as well as between Cr, Fe and Mn.These data present normal variability of 24h excretion of a number of elements, and can also be used as updated reference levels for elements with no or limited previous literature available. Information on variability within- and between individuals is important to know when designing studies with urine levels of elements used as exposure biomarker in studies of associations with health outcomes.
|
|
| 2. |
- Hamacher-Barth, Evelyne, 1962-
(author)
-
The high Arctic summer aerosol : Size, chemical composition, morphology and evolution over the pack-ice
- 2017
-
Doctoral thesis (other academic/artistic)abstract
- Aerosol particles, especially in the high Arctic are still not very well represented in climate models. Particle size and number concentrations are strongly under-predicted and temporal variations of aerosol composition and size are still not very well understood, mainly due to the sparsity of observations.The main objective of this thesis is the characterization of the high Arctic summer aerosol by means of electron microscopy in order to extend the existing data set from previous expeditions by size resolved data on aerosol number, morphology and chemical composition and to gain a better understanding of the evolution of the aerosol in the atmosphere.Ambient aerosol was collected over the pack ice during the Arctic Summer Cloud and Ocean (ASCOS) campaign to the high Arctic in summer 2008. Aerosol particles were evaluated with scanning electron microscopy and subsequent digital image processing to assess particle size and morphology. More than 3900 aerosol particles from 9 sampling events were imaged with scanning electron microscopy and merged into groups of similar morphology which contributed to different degrees to the total aerosol: single particles (82%), gel particles (11%) and halo particles (7%). Single particles were observed over the whole size range with a maximum at 64 nm in diameter, gel particles appeared > 45 nm with a maximum in number at 174 nm, halo particles appeared > 75 nm with a maximum in number at 161 nm. The majority of particles showed the morphology of marine gels, no sea salt or otherwise crystalline particles were observed. Transmission electron microscopy enabled more subtle insights into particle morphology and allowed further subdivision of gel particles into aggregates, aggregates with film and mucus-like particles. Energy dispersive X-ray spectroscopy of individual particles revealed a gradual transition in the content of Na+/K+ and Ca2+/Mg2+ between particle morphologies. Single particles and aggregate particles preferentially contained Na+/K+ whereas aggregate with film particles and mucus-like particles mainly contained Ca2+/Mg2+ suggesting a connection between particle morphology and ion content. Back-trajectory analysis was used to identify aerosol sources and to understand the evolution of the aerosol as a function of the synoptic weather situation. Particle numbers, size and morphology changed with the days the air mass spent over the pack-ice. A morphological descriptor applied to gel particles showed a clear trend suggesting that the contour of the particles becomes sharper and more distinct with increased time spent over the pack-ice. For a very long time over the pack-ice, however, we observed a morphology comparable to freshly emitted particles suggesting aerosol sources over the inner pack-ice.Size resolved aerosol chemical composition measurements were utilized to investigate the inorganic composition of laboratory generated nascent sea spray aerosol particles and ambient aerosol samples collected during ASCOS. A significant enrichment of Ca2+ was observed in submicrometer particles in either case with a tendency for increasing Ca2+ enrichment with decreasing particle size. This has strong implications for the alkalinity of sea spray aerosol particles with consequences for the sulfur chemistry in the marine boundary layer, the hygroscopicity and thus the potential of sea spray aerosol particles to act as cloud condensation nuclei.
|
|
| 3. |
- Weinbruch, Stephan, et al.
(author)
-
Chemical composition and sources of aerosol particles at Zeppelin Mountain (Ny Alesund, Svalbard) : An electron microscopy study
- 2012
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 49, s. 142-150
-
Journal article (peer-reviewed)abstract
- Aerosol particles were collected at the Zeppelin Mountain Atmospheric Research Station (474 m asl) near Ny Alesund (Svalbard, Norway) on 27 different days between July 2007 and December 2008. The size, morphology and chemical composition of 57,617 individual particles were studied by high-resolution scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on chemical composition, morphology, mixing state and stability under electron bombardment, the particles were assigned to one of the following groups: sea salt, aged sea salt, Ca sulphates, Na sulphates, carbonates, soot, silicates, fly ashes, secondary aerosol, secondary aerosol plus sodium, secondary aerosol plus soot, mixed particles and others. Sea salt, aged sea salt, silicates and mixed particles (mixtures of sea salt, silicates and Ca sulphates) are the most abundant groups for particles with aerodynamic diameters > 0.5 mu m, secondary aerosol, mixed particles and secondary aerosol with soot inclusions below 0.5 mu m. Silicate fly ashes (major source coal burning) and metal fly ashes (from metallurgical high temperature processes) occur only at very low number concentrations. In contrast to previous work, the fly ash abundance is not correlated with air masses that crossed industrialized regions in Central and Eastern Europe, Scandinavia or Russia. These observations indicate a significant reduction of long-range transport of heavy metals to Svalbard. Soot (external and internally mixed with secondary aerosol) shows a pronounced seasonal pattern with a much lower abundance during summer compared to spring, autumn and winter. The soot abundance is not correlated with the air mass back-trajectories. During summer (July and August), soot was only observed when cruise ships were present in the area around Ny Alesund (Kongsfjorden). Pronounced seasonal patterns were observed for the abundance of the mineral dust component which is generally lower in summer compared to the other seasons. The observed seasonal dependence of anthropogenic primary particles (soot, fly ashes) is in good agreement with the Arctic circulation pattern.
|
|
