Combined uncertainty estimation for the determination of the dissolved iron amount content in seawater using flow injection with chemiluminescence detection

This work assesses the components contributing to the combined uncertainty budget associated with the measurement of the Fe amount content by flow injection chemiluminescence (FI-CL) in <0.2 μm filtered and acidified seawater samples. Amounts of loaded standard solutions and samples were determined gravimetrically by differential weighing. Up to 5% variations in the loaded masses were observed during measurements, in contradiction to the usual assumptions made when operating under constant loading time conditions. Hence signal intensities (V) were normalised to the loaded mass and plots of average normalized intensities (in V kg-1) versus values of the Fe amount content (in nmol kg-1) added to a ‘low level’ iron seawater matrix were used to produce the calibration graphs. The measurement procedure implemented and the uncertainty estimation process developed were validated from the agreement obtained with consensus values for three SAFe and GEOTRACES reference materials (D2, GS and GD). Relative expanded uncertainties for peak height and peak area based results were estimated to be around 12% and 10% (k=2) respectively. The most important contributory factors were the uncertainty on the sensitivity coefficient (i.e. calibration slope) and within-sequence-stability (i.e. the signal stability measured over several hours of operation; in this case 32 h). Therefore, an uncertainty estimation based on the intensity repeatability alone, as is often done in FI-CL studies, is not a realistic estimation of the overall uncertainty of the procedure.JRC.D.2-Standards for Innovation and sustainable Developmen

Effect of a sport-for-health intervention (SmokeFree Sports) on smoking-related intentions and cognitions among 9-10 year old primary school children: a controlled trial.

BACKGROUND: Preventing children from smoking is a public health priority. This study evaluated the effects of a sport-for-health smoking prevention programme (SmokeFree Sports) on smoking-related intentions and cognitions among primary school children from deprived communities. METHODS: A non-randomised-controlled trial targeted 9-10 year old children from Merseyside, North-West England. 32 primary schools received a programme of sport-for-health activities over 7 months; 11 comparison schools followed usual routines. Data were collected pre-intervention (T0), and at 8 months (T1) and one year post-intervention (T2). Smoking-related intentions and cognitions were assessed using an online questionnaire. Intervention effects were analysed using multi-level modelling (school, student), adjusted for baseline values and potential confounders. Mixed-sex focus groups (n = 18) were conducted at T1. RESULTS: 961 children completed all assessments and were included in the final analyses. There were no significant differences between the two study groups for non-smoking intentions (T1: β = 0.02, 95 % CI = -0.08-0.12; T2: β = 0.08, 95 % CI = -0.02-0.17) or for cigarette refusal self-efficacy (T1: β = 0.28, 95 % CI = -0.11-0.67; T2: β = 0.23, 95 % CI = -0.07-0.52). At T1 there was a positive intervention effect for cigarette refusal self-efficacy in girls (β = 0.72, 95 % CI = 0.21-1.23). Intervention participants were more likely to 'definitely' believe that: 'it is not safe to smoke for a year or two as long as you quit after that' (RR = 1.19, 95 % CI = 1.07-1.33), 'it is difficult to quit smoking once started' (RR = 1.56, 95 % CI = 1.38-1.76), 'smoke from other peoples' cigarettes is harmful' (RR = 1.19, 95 % CI = 1.20-2.08), 'smoking affects sports performance' (RR = 1.73, 95 % CI = 1.59-1.88) and 'smoking makes 'no difference' to weight' (RR = 2.13, 95 % CI = 1.86-2.44). At T2, significant between-group differences remained just for 'smoking affects sports performance' (RR = 1.57, 95 % CI = 1.43-1.72). Focus groups showed that SFS made children determined to remain smoke free and that the interactive activities aided children's understanding of smoking harms. CONCLUSION: SFS demonstrated short-term positive effects on smoking attitudes among children, and cigarette refusal self-efficacy among girls. Although no effects were observed for non-smoking intentions, children said that SFS made them more determined not to smoke. Most children had strong intentions not to smoke; therefore, smoking prevention programmes should perhaps target early adolescents, who are closer to the age of smoking onset

Uncertainty associated with the leaching of aerosol filters for the determination of metals in aerosol particulate matter using collision/reaction cell ICP-MS detection

© 2019 Elsevier B.V. High quality observational data with a firm uncertainty assessment are essential for the proper validation of biogeochemical models for trace metals such as iron. Typically, concentrations of these metals are very low in oceanic waters (nM and sub nM) and ICP-MS is therefore a favoured technique for quantitative analysis. Uncertainties in the measurement step are generally well constrained, even at sub-nM concentrations. However, the measurement step is only part of the overall procedure. For the determination of trace metal solubilities from aerosols in the surface ocean, aerosol collection on a filter paper followed by a leaching procedure is likely to make a significant contribution to the overall uncertainty. This paper quantifies the uncertainties for key trace metals (cobalt, iron, lead and vanadium), together with aluminium as a reference element, for a controlled, flow through laboratory leaching procedure using filters collected from three different sampling sites (Tudor Hill (Bermuda), Heraklion (Crete) and Tel-Shikmona (Israel)) and water, glucuronic acid and desferrioxamine B as leachants. Relative expanded uncertainties were in the range of 12–29% for cobalt, 12–62% for iron, 13–45% for lead and 5–11% for vanadium. Fractional solubilities for iron ranged from 0.2 ± 0.1% to 16.9 ± 3.5%

Resisting the mantle of the monstrous feminine : women's construction and experience of premenstrual embodiment

The female reproductive body is positioned as abject, as other, as site of defciency and disease, the epitome of the ‘monstrous feminine.’ Premenstrual change in emotion, behavior or embodied sensation is positioned as a sign of madness within, necessitating restraint and control on the part of the women experiencing it (Ussher 2006). Breakdown in this control through manifestation of ‘symptoms’ is diagnosed as PMS (Premenstrual Syndrome) or PMDD (Premenstrual Dysphoric Disorder), a pathology deserving of ‘treatment.’ In this chapter, we adopt a feminist material-discursive theoretical framework to examine the role of premenstrual embodiment in relation to women’s adoption of the subject position of monstrous feminine, drawing on interviews we have conducted with women who self-diagnose as ‘PMS sufferers.’ We theorize women’s self-positioning as subjectifcation, wherein women take up cultural discourse associated with idealized femininity and the reproductive body, resulting in self-objectifcation, distress, and self-condemnation. However, women can resist negative cultural constructions of premenstrual embodiment and the subsequent self-policing. We describe the impact of women-centered psychological therapy which increases awareness of embodied change, and leads to greater acceptance of the premenstrual body and greater self-care, which serves to reduce premenstrual distress

Impact of surface ocean conditions and aerosol provenance on the dissolution of aerosol manganese, cobalt, nickel and lead in seawater

© 2017. Atmospheric deposition is an important pathway by which bioactive trace metals are delivered to the surface ocean. The proportions of total aerosol trace metals that dissolve in seawater, and thus become available to biota, are not well constrained and are therefore a key uncertainty when estimating atmospheric fluxes of these elements to surface waters. The aim of this study was to elucidate the main physico-chemical controls on the dissolution of the bioactive trace metals manganese (Mn), cobalt (Co), nickel (Ni) and lead (Pb). To this end, aerosol and surface seawater samples were collected in the Sargasso Sea and subsequently used in sequential seawater leach dissolution experiments to assess the role of aerosol source, seawater temperature, pH, and concentrations of dissolved oxygen and organic ligands, on aerosol trace metal dissolution.Results reveal that changes in key physico-chemical parameters in seawater leaches had little effect on the proportions of Mn, Co, Ni and Pb released from aerosols, although organic ligand amendments impacted the size distribution of aerosol-derived Mn in solution. Conversely, aerosol source and composition had the most significant effect on the dissolution of aerosol Co and Pb, with the most 'anthropogenic' aerosol samples displaying the highest fractional solubilities in seawater (up to 58% for Co and 112% for Pb).Fractional solubilities over the range of samples and conditions tested were in the range of 50-104% for Mn, 29-58% for Co, 40-85% for Ni and 67-112% for Pb. A large proportion (36-100%, median 89%) of the total dMn, dCo, dNi and dPb was mobilised rapidly during the first leaching step (5. min), with less dTM being released in leaches 2 through 4. Furthermore, investigation of the size distribution of the aerosol-derived trace metals in seawater showed that dissolved Pb was mostly colloidal (0.02-0.4. μm), dissolved Mn and Co were mostly soluble ( < . 0.02. μm), and dissolved Ni displayed a mixed size distribution. Good empirical relationships were observed between enrichment factors for aerosol antimony (Sb) and the fractional solubilities of aerosol Fe, Co and Pb, suggesting total aerosol Sb can be useful in estimating and modelling the fractional solubility of these metals using total aerosol trace metal concentrations from historical data

Automated, high frequency, on-line dimethyl sulfide measurements in natural waters using a novel “microslug” gas-liquid segmented flow method with chemiluminescence detection

Dimethyl sulfide (DMS) is the major biogenic volatile sulfur compound in surface seawater. Good quality DMS data with high temporal and spatial resolution are desirable for understanding reduced sulfur biogeochemistry. Here we present a fully automated and novel “microslug” gas-liquid segmented flow-chemiluminescence (MSSFCL) based method for the continuous in-situ measurement of DMS in natural waters. Samples were collected into a flow tank and DMS transferred from the aqueous phase to the gas phase using a vario-directional coiled flow, in which microvolume liquid and gas slugs were interspersed. The separated DMS was reacted with ozone in a reaction cell for CL detection. The analytical process was automated, with a sample throughput of 6.6 h− 1. Using MSSF for DMS separation was more effective and easily integrated with CL detection compared with the commonly used bubbling approach. Key parameters of the proposed method were investigated. The linear range for the method was 0.05–500 nM (R2 = 0.9984) and the limit of detection (3 x S/N) was 0.015 nM, which is comparable to the commonly used gas chromatography (GC) method and sensitive enough for direct DMS measurement in typical aquatic environments. Reproducibility and recovery were assessed by spiking natural water samples (river, lake, reservoir and pond) with different concentrations of DMS (10, 20 and 50 nM), giving relative standard deviations (RSDs) ≤1.75% (n = 5) and recoveries of 94.4–107.8%. This fully automated system is reagent free, easy to assemble, simple to use, portable (weight ~5.1 kg) and can be left in the field for several hours of unattended operation. The instrumentation can provide high quality DMS data for natural waters with an environmentally relevant temporal resolution of ~9 min

Increasing picocyanobacteria success in shelf waters contributes to long-term food web degradation

Continental margins are disproportionally important for global primary production, fisheries and CO2 uptake. However, across the Northeast Atlantic shelves, there has been an ongoing summertime decline of key biota—large diatoms, dinoflagellates and copepods—that traditionally fuel higher tropic levels such as fish, sea birds and marine mammals. Here, we combine multiple time series with in situ process studies to link these declines to summer nutrient stress and increasing proportions of picophytoplankton that can comprise up to 90% of the combined pico- and nanophytoplankton biomass in coastal areas. Among the pico-fraction, it is the cyanobacterium Synechococcus that flourishes when iron and nitrogen resupply to surface waters are diminished. Our field data show how traits beyond small size give Synechococcus a competitive edge over pico- and nanoeukaryotes. Key is their ability to grow at low irradiances near the nutricline, which is aided by their superior light-harvesting system and high affinity to iron. However, minute size and lack of essential biomolecules (e.g. omega-3 polyunsaturated fatty acids and sterols) render Synechococcus poor primary producers to sustain shelf sea food webs efficiently. The combination of earlier spring blooms and lower summer food quantity and quality creates an increasing period of suboptimal feeding conditions for zooplankton at a time of year when their metabolic demand is highest. We suggest that this nutrition-related mismatch has contributed to the widespread, ~50% decline in summer copepod abundance we observe over the last 60 years. With Synechococcus clades being prominent from the tropics to the Arctic and their abundances increasing worldwide, our study informs projections of future food web dynamics in coastal and shelf areas where droughts and stratification lead to increasing nutrient starvation of surface waters

Realistic measurement uncertainties for marine macronutrient measurements conducted using gas segmented flow and Lab-on-Chip techniques

Highlights • Accounting for systematic bias is required for a realistic analytical uncertainty • Gas segmented flow techniques achieved a combined uncertainties of 1-4 % • Lab-on-Chip nitrate + nitrite analysers achieved a combined uncertainties < 5% Abstract Accurate and precise measurements of marine macronutrient concentrations are fundamental to our understanding of biogeochemical cycles in the ocean. Quantifying the measurement uncertainty associated with macronutrient measurements remains a challenge. Large systematic biases (up to 10 %) have been identified between datasets, restricting the ability of marine biogeochemists to distinguish between the effects of environmental processes and analytical uncertainty. In this study we combine the routine analyses of certified reference materials (CRMs) with the application of a simple statistical technique to quantify the combined (random + systematic) measurement uncertainty associated with marine macronutrient measurements using gas segmented flow techniques. We demonstrate that it is realistic to achieve combined uncertainties of ~1-4 % for nitrate + nitrite (ΣNOx), phosphate (PO43-) and silicic acid (Si(OH)4) measurements. This approach requires only the routine analyses of CRMs (i.e. it does not require inter-comparison exercises). As CRMs for marine macronutrients are now commercially available, it is advocated that this simple approach can improve the comparability of marine macronutrient datasets and therefore should be adopted as ‘best practice’. Novel autonomous Lab-on-Chip (LoC) technology is currently maturing to a point where it will soon become part of the marine chemist’s standard analytical toolkit used to determine marine macronutrient concentrations. Therefore, it is critical that a complete understanding of the measurement uncertainty of data produced by LoC analysers is achieved. In this study we analysed CRMs using 7 different LoC ΣNOx analysers to estimate a combined measurement uncertainty of < 5%. This demonstrates that with high quality manufacturing and laboratory practices, LoC analysers routinely produce high quality measurements of marine macronutrient concentrations

Dissolved iron in the Bermuda region of the subtropical North Atlantic Ocean: Seasonal dynamics, mesoscale variability, and physicochemical speciation

18 months embargo minus one day to account for leap year