Search

In order to ensure radiation monitoring and protection, investigation and assessment of radiological risks that may be associated with the consumption of packaged table waters commonly consumed in Ogbomoso and Ilorin metropolis, Nigeria, was carried out. The measurements were carried out using a '3 x 3' inch lead-shielded NaI (Tl) detector coupled through coaxial cable to a multichannel analyser. The measured activity concentrations of the natural radionuclides in the packaged drinking water sample are mostly within the recommended limits. The estimated mean Annual Effective Dose was found to be within the acceptable limits of 1 mSv/y for the general populace except for the infants which is slightly higher for some of the samples. The estimated Excess Lifetime Cancer Risk were found to be lower than the world average value of 0.2 x 10-3 in only two of the selected packaged drinking water. This implies the possibility of developing cancer over a lifetime considering seventy years as the average life span is considerably high. [ABSTRACT FROM AUTHOR]

The Surface PARTiculate mAtter Network (SPARTAN) is a long-term project that includes characterization of chemical and physical attributes of aerosols from filter samples collected worldwide. This paper discusses the ongoing efforts of SPARTAN to define and quantify major ions and trace metals found in fine particulate matter (PM2:5). Our methods infer the spatial and temporal variability of PM2:5 in a cost-effective manner. Gravimetrically weighed filters represent multi-day averages of PM2:5, with a collocated nephelometer sampling air continuously. SPARTAN instruments are paired with AErosol RObotic NETwork (AERONET) sun photometers to better understand the relationship between ground-level PM2:5 and columnar aerosol optical depth (AOD). We have examined the chemical composition of PM2:5 at 12 globally dispersed, densely populated urban locations and a site at Mammoth Cave (US) National Park used as a background comparison. So far, each SPARTAN location has been active between the years 2013 and 2016 over periods of 2-26 months, with an average period of 12 months per site. These sites have collectively gathered over 10 years of quality aerosol data. The major PM2:5 constituents across all sites (relative contribution±SD) are ammoniated sulfate (20%±11%), crustal material (13.4% ±9.9%), equivalent black carbon (11.9%±8.4%), ammonium nitrate (4.7%±3.0%), sea salt (2.3%± 1.6%), trace element oxides (1.0%±1.1%), water (7.2% ±3.3%) at 35% RH, and residual matter (40%±24%). Analysis of filter samples reveals that several PM2:5 chemical components varied by more than an order of magnitude between sites. Ammoniated sulfate ranges from 1.1 µgm-3 (Buenos Aires, Argentina) to 17 µgm-3 (Kanpur, India in the dry season). Ammonium nitrate ranged from 0.2 µgm-3 (Mammoth Cave, in summer) to 6.8 µgm-3 (Kanpur, dry season). Equivalent black carbon ranged from 0.7 µgm-3 (Mammoth Cave) to over 8 µgm-3 (Dhaka, Bangladesh and Kanpur, India). Comparison of SPARTAN vs. coincident measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network at Mammoth Cave yielded a high degree of consistency for daily PM2:5 (r² = 0.76, slopeD1.12), daily sulfate (r² = 0.86, slopeD1.03), and mean fractions of all major PM2:5 components (within 6%). Major ions generally agree well with previous studies at the same urban locations (e.g. sulfate fractions agree within 4% for 8 out of 11 collocation comparisons). Enhanced anthropogenic dust fractions in large urban areas (e.g. Singapore, Kanpur, Hanoi, and Dhaka) are apparent from high Zn : Al ratios. The expected water contribution to aerosols is calculated via the hygroscopicity parameter Kv for each filter. Mean aggregate values ranged from 0.15 (Ilorin) to 0.28 (Rehovot). The all-site parameter mean is 0.20±0.04. Chemical composition and water retention in each filter measurement allows inference of hourly PM2:5 at 35% relative humidity by merging with nephelometer measurements. These hourly PM2:5 estimates compare favourably with a beta attenuation monitor (MetOne) at the nearby US embassy in Beijing, with a coefficient of variation r² = 0.67 (n = 3167), compared to r² = 0.62 when Kv was not considered. SPARTAN continues to provide an open-access database of PM2:5 compositional filter information and hourly mass collected from a global federation of instruments. [ABSTRACT FROM AUTHOR]

Global ground-level measurements of elements in ambient particulate matter (PM) can provide valuable information to understand the distribution of dust and trace elements, assess health impacts, and investigate emission sources. We use X-ray fluorescence spectroscopy to characterize the elemental composition of PM samples collected from 27 globally distributed sites in the Surface PARTiculate mAtter Network (SPARTAN) over 2019-2023. Consistent protocols are applied to collect all samples and analyze them at one central laboratory, which facilitates comparison across different sites. Multiple quality assurance measures are performed, including applying reference materials that resemble typical PM samples, acceptance testing, and routine quality control. Method detection limits and uncertainties are estimated. Concentrations of dust and trace element oxides (TEO) are determined from the elemental dataset. In addition to sites in arid regions, a moderately high mean dust concentration (6 μg/m 3 ) in PM 2.5 is also found in Dhaka (Bangladesh) along with a high average TEO level (6 μg/m 3 ). High carcinogenic risk (>1 cancer case per 100000 adults) from airborne arsenic is observed in Dhaka (Bangladesh), Kanpur (India), and Hanoi (Vietnam). Industries of informal lead-acid battery and e-waste recycling as well as coal-fired brick kilns likely contribute to the elevated trace element concentrations found in Dhaka., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Exposure to ambient fine particulate matter (PM 2.5 ) is a leading risk factor for the global burden of disease. However, uncertainty remains about PM 2.5 sources. We use a global chemical transport model (GEOS-Chem) simulation for 2014, constrained by satellite-based estimates of PM 2.5 to interpret globally dispersed PM 2.5 mass and composition measurements from the ground-based surface particulate matter network (SPARTAN). Measured site mean PM 2.5 composition varies substantially for secondary inorganic aerosols (2.4-19.7 μg/m 3 ), mineral dust (1.9-14.7 μg/m 3 ), residual/organic matter (2.1-40.2 μg/m 3 ), and black carbon (1.0-7.3 μg/m 3 ). Interpretation of these measurements with the GEOS-Chem model yields insight into sources affecting each site. Globally, combustion sectors such as residential energy use (7.9 μg/m 3 ), industry (6.5 μg/m 3 ), and power generation (5.6 μg/m 3 ) are leading sources of outdoor global population-weighted PM 2.5 concentrations. Global population-weighted organic mass is driven by the residential energy sector (64%) whereas population-weighted secondary inorganic concentrations arise primarily from industry (33%) and power generation (32%). Simulation-measurement biases for ammonium nitrate and dust identify uncertainty in agricultural and crustal sources. Interpretation of initial PM 2.5 mass and composition measurements from SPARTAN with the GEOS-Chem model constrained by satellite-based PM 2.5 provides insight into sources and processes that influence the global spatial variation in PM 2.5 composition.