Atmospheric trace metals measured at a regional background site (Welgegund) in South Africa

Venter, Andrew D.; Zyl, P. G. van; Beukes, J. P.; Josipovic, Micky; Hendriks, Johan; Vakkari, Ville; Laakso, Lauri

doi:10.5194/acp-17-4251-2017

Cited by 53 publications

(16 citation statements)

References 30 publications

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“…The observed concentrations of most elements were higher than those observed at other regional background regions in Southern Africa and Europe. For elements such as Ca, Al, Fe, and Zn the concentrations in this study were higher than those reported for similar background regions in Welgegung, South Africa (Venter et al, 2017) 3.0 ng/m³), respectively, in comparison to Welgegung (7.9, 6.9 ng/m³) and Puy de Dôme (1.9, 5.8 ng/m 3 ). Sb concentration in this study were higher than at Welgegung and Puy de Dôme sites but lower than those observed at other urban sites (Cheng et al, 2000).…”

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confidence: 84%

Application of TXRF in monitoring trace metals in particulate matter and cloud water

Fomba¹,

Deabji²,

Barcha³

et al. 2020

Preprint

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Ambient particulate matter and cloud trace metals are considered key elements of atmospheric processes as they affect air quality, environmental ecosystems and play an important role in cloud formation. However, they are often available at trace concentrations in these media such that their analysis requires high precision and 15 sensitive techniques. In this study, different analytical methods were applied to quantify trace metals in particulate matter samples collected on quartz and polycarbonate filters as well as cloud water, using the Total reflection X-Ray Fluorescence (TXRF) technique. These methods considered the direct measurement of filter samples with and without chemical pretreatment. Direct measurements involved analysis of as collected polycarbonate and cloud water samples after they are brought onto TXRF carrier substrates. For the chemical treatment, different acid 20 digestion procedures for PM on Quartz filters were assessed including reverse aqua regia, nitric acid and a combination of nitric acid and hydrogen peroxide solution. The effect of cold-plasma treatment of samples on polycarbonate filters prior to TXRF measurements was also investigated.Digestion with the reverse aqua regia solution provided lower blanks and higher recovery in comparison to other tested procedures. The detection limits of the elements ranged from 0.3 to 44 ng/cm². Ca, K, Zn, and Fe showed 25 the highest detection limits of 44, 35, 6 and 1 ng/cm² while As and Se had the lowest of 0.3 and 0.8 ng/cm², respectively. The method showed higher recovery for most trace metals when applied to commercially available reference materials and field samples. TXRF measurements showed good agreement with results obtained from ion chromatography measurements for elements such as Ca and K. Cold plasma treatment did not significantly lead to an increase in the detected concentration and the results were element-specific. Backing of the quartz filters 30 prior to sampling showed a reduction of more than 20% of the filter blanks for elements such as V, Sr, Mn, Zn, Sb.The methods were applied successfully on ambient particulate matter and cloud water samples collected from the Atlas Mohammed V station in Morocco and the Cape Verde Atmospheric Observatory. The obtained concentrations were within the range reported using different techniques from similar remote and background 35 regions elsewhere, especially for elements of anthropogenic origins such as V, Pb, and Zn with concentrations of up to 10, 19 and 28 ng/m³, respectively. Enrichment factor analysis indicated that crustal matter dominated the abundance of most of the elements while anthropogenic activities also contributed to the abundance of elements such as Sb, Se, and Pb. The results confirm that TXRF is a useful complementary sensitive technique for trace metal analysis of particulate matter in the microgram range as well as in cloud water droplets.

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contrasting

confidence: 84%

Application of TXRF in monitoring trace metals in particulate matter and cloud water

Fomba¹,

Deabji²,

Barcha³

et al. 2020

Preprint

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“…The results showed that wind speeds in the region are highly influential, by transporting particulate matter from adjoining regions to the sampling location, and thereby, contributing to the TMB, whereas negative correlation with RH is probably due to the wash out processes by rains [87]. Significant correlations (r 2 = 0.41-0.78) of TMB vs AT found in all the localities were attributed to the fact that more favorable atmospheric dispersion conditions and photochemical reactions prevail under warm conditions [88]. Positive correlations of Mn vs Cu (r 2 = 0.83) and Zn (r 2 = 0.76), when p < 0.05 in the rainwater collected at the urban center of Gustavo A. Madero (Table 4), indicated the influence of local road traffic and automobile exhausts [89].…”

Section: Discussionmentioning

confidence: 99%

Evidence of Natural and Anthropogenic Impacts on Rainwater Trace Metal Geochemistry in Central Mexico: A Statistical Approach

Rivera-Rivera

Escobedo-Urías

Jonathan

et al. 2020

Water

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Trace metals Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, and As were determined on a monthly basis in a total of 52 rain samples collected from six different locations in the central region of Mexico during March 2016–April 2017. The average concentrations of trace metals (mg/L) in the rainwater samples showed an order of Zn (0.873) > Fe (0.395) > Mn (0.083) > Cr (0.041) ≥ Cu (0.041) > Pb (0.031) > Ni (0.020) > Co (0.013) > As (0.0003) > Cd (0.002). The differences observed in metal concentrations are related to variations in the influence of continental air masses, local transport, regional advection, and the solubility of trace metals. High concentrations of metals were observed in the months of March to May at all sites, probably due to the less extensive removal of air/air pollutants. The values obtained from the enrichment factor (EF) per metal showed relatively high values for Cd, Zn, Cu, Pb, Co, Ni, and Cr, suggesting anthropogenic origin. Pearson’s correlation matrix validated the distribution of trace metal sources and their relationships with local/regional meteorological characteristics. This paper presents relevant basic information for the evaluation of the toxic potential of rainwater and the possible health risks when using this source of water for human consumption.

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“…Whiteface Mountain Summit, Beltsville, Ispra, Ryori, and Seokmo-Ri Ga). However, there are other sites in the Northern Hemisphere where a summer maximum is more evident (Vingarzan, 2004), i.e. Joshua Tree and Hohenpeissenberg.…”

Section: Comparison With International Sitesmentioning

confidence: 99%

Seasonal influences on surface ozone variability in continental South Africa and implications for air quality

et al. 2018

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Abstract. Although elevated surface ozone (O3) concentrations are observed in many areas within southern Africa, few studies have investigated the regional atmospheric chemistry and dominant atmospheric processes driving surface O3 formation in this region. Therefore, an assessment of comprehensive continuous surface O3 measurements performed at four sites in continental South Africa was conducted. The regional O3 problem was evident, with O3 concentrations regularly exceeding the South African air quality standard limit, while O3 levels were higher compared to other background sites in the Southern Hemisphere. The temporal O3 patterns observed at the four sites resembled typical trends for O3 in continental South Africa, with O3 concentrations peaking in late winter and early spring. Increased O3 concentrations in winter were indicative of increased emissions of O3 precursors from household combustion and other low-level sources, while a spring maximum observed at all the sites was attributed to increased regional biomass burning. Source area maps of O3 and CO indicated significantly higher O3 and CO concentrations associated with air masses passing over a region with increased seasonal open biomass burning, which indicated CO associated with open biomass burning as a major source of O3 in continental South Africa. A strong correlation between O3 on CO was observed, while O3 levels remained relatively constant or decreased with increasing NOx, which supports a VOC-limited regime. The instantaneous production rate of O3 calculated at Welgegund indicated that ∼40 % of O3 production occurred in the VOC-limited regime. The relationship between O3 and precursor species suggests that continental South Africa can be considered VOC limited, which can be attributed to high anthropogenic emissions of NOx in the interior of South Africa. The study indicated that the most effective emission control strategy to reduce O3 levels in continental South Africa should be CO and VOC reduction, mainly associated with household combustion and regional open biomass burning.

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Atmospheric trace metals measured at a regional background site (Welgegund) in South Africa

Cited by 53 publications

References 30 publications

Application of TXRF in monitoring trace metals in particulate matter and cloud water

Application of TXRF in monitoring trace metals in particulate matter and cloud water

Evidence of Natural and Anthropogenic Impacts on Rainwater Trace Metal Geochemistry in Central Mexico: A Statistical Approach

Seasonal influences on surface ozone variability in continental South Africa and implications for air quality

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