Occurrence and sources of aliphatic hydrocarbons in surface soils from Riyadh city, Saudi Arabia

AbstractSoil particles contain a variety of anthropogenic and natural organic components derived from many sources such as industrial and traffic fossil fuel emissions and terrestrial biota. The organic contents of soil and sand from the Arabian region have not fully characterized. Thus, samples of fine soil particles (sieved to <125μM) were collected from the Riyadh area in November 2006 (late summer) and February 2007 (late winter). The samples were extracted with a mixture of dichloromethane/hexane and analyzed by gas chromatography–mass spectroscopy (GCMS) in order to characterize the chemical composition and sources of aliphatic hydrocarbons. The results showed that both anthropogenic and natural biogenic inputs were the major sources of the aliphatic hydrocarbons in these extracts. Vehicular emission products and discarded plastics were the major anthropogenic sources in the fine particles of the soils and ranged from 64% to 96% in November 2006 and from 70% to 92% in February 2007. Their tracers were n-alkanes, hopanes, sterane, plasticizers and UCM. Vegetation was also a major natural source of hydrocarbon compounds in samples ranging from ∼0% to18% in November 2006 and from 1% to 13% in February 2007 and included n-alkanes and triterpenoids

Occurrence and sources of natural and anthropogenic lipid tracers in surface soils from arid urban areas of Saudi Arabia

Soil particles contain a variety of natural and anthropogenic organic components, and in urban areas can be considered as local collectors of pollutants. Surface soil samples were taken from ten urban areas in Riyadh during early winter of 2007. They were extracted with dichloromethane-methanol mixture and the extracts were analyzed by gas chromatography-mass spectrometry. The major compounds were unresolved complex mixture (UCM), plasticizers, n-alkanes, carbohydrates, n-alkanoic acids, hopanes, n-alkanols, and sterols. Vegetation detritus was the major natural source of organic compounds (24.0 ± 15.7%) in samples from areas with less human activities and included n-alkanes, n-alkanoic acids, n-alkanols, sterols and carbohydrates. Vehicular emission products and discarded plastics were the major anthropogenic sources in the soil particles (53.3 ± 21.3% and 22.7 ± 10.7%, respectively). The anthropogenic tracers were UCM, plasticizers, n-alkanes, hopanes and traces of steranes. Vegetation and human activities control the occurrence and distribution of natural and anthropogenic extractable organic matter in this arid urban area.Keywords: Petroleum residues, Biomarkers, Soils, Lipids, Plasticizer

Organic Tracers from Asphalt in Propolis Produced by Urban Honey Bees, Apis mellifera Linn.

Propolis is a gummy material produced by honey bees to protect their hives and currently has drawn the attention of researchers due to its broad clinical use. It has been reported, based only on observations, that honey bees also collect other non-vegetation substances such as paint or asphalt/tar to make propolis. Therefore, propolis samples were collected from bee hives in Riyadh and Al-Bahah, a natural area, Saudi Arabia to determine their compositional characteristics and possible sources of the neutral organic compounds. The samples were extracted with hexane and analyzed by gas chromatography-mass spectrometry. The results showed that the major compounds were n-alkanes, n-alkenes, methyl n-alkanoates, long chain wax esters, triterpenoids and hopanes. The n-alkanes (ranging from C17 to C40) were significant with relative concentrations varying from 23.8 to 56.8% (mean = 44.9±9.4%) of the total extracts. Their odd carbon preference index (CPI) ranged from 3.6 to 7.7, with a maximum concentration at heptacosane indicating inputs from higher plant vegetation wax. The relative concentrations of the n-alkenes varied from 23.8 to 41.19% (mean = 35.6±5.1%), with CPI = 12.4-31.4, range from C25 to C35 and maximum at tritriacontane. Methyl n-alkanoates, ranged from C12 to C26 as acids, with concentrations from 3.11 to 33.2%(mean = 9.6±9.5%). Long chain wax esters and triterpenoids were minor. The main triterpenoids were α- and β-amyrins, amyrones and amyryl acetates. The presence of hopanes in some total extracts (up to 12.5%) indicated that the bees also collected petroleum derivatives from vicinal asphalt and used that as an additional ingredient to make propolis. Therefore, caution should be taken when considering the chemical compositions of propolis as potential sources of natural products for biological and pharmacological applications. Moreover, beekeepers should be aware of the proper source of propolis in the flight range of their bee colonies

Air quality and elemental enrichment factors of aerosol particulate matter in Riyadh City, Saudi Arabia

Air particulate matter (PM) samples were collected from June 2006 to May 2007 for determination chemical elements. PM samples were taken in two size fractions (PM₂.₅ and PM₁₀) with MiniVolume air samplers on rooftops of various buildings (15-25 m above ground) in the city of Riyadh. The samples were subjected to XRF analysis to measure major (Na, Mg, Al, K, Ca, Si, P, S and Fe) and trace elements (Mn, Ni, Cu, Zn, and Ba). The results showed that the PM concentrations were higher for PM₁₀ compared to PM₂.₅, indicating that the major PM source was local dust. Also the spatial distribution with high PM concentrations was observed in the south and southeast of the city and the lowest levels were in the center and northeast of the city. This spatial distribution was attributed to different factors such as wind direction and velocity, emission from cement factories, presence of buildings, trees and paved streets that reduce the amount of dust resuspended into the atmosphere. The air quality of the city was found to range from good to hazardous based on PM₂.₅ and from good to very hazardous based on PM₁₀. The element enrichment factors revealed two element groups according to their changing spatial behavior. The first group showed no significant spatial changes indicating they have the same common source. The second group (mainly S and Ni) exhibited significant changes as expected from anthropogenic inputs. The origin of S is possibly a combination of minerals (CaSO₄) and fossil fuel combustion. The source of Ni is probably from fossil fuel combustion.KEYWORDS: Particulate matter, PM₁₀, Enrichment factor, Air quality, PM₂.₅, Riyadh, Major and trace element

RushdiAhmedCEOASAirQualityElemental.pdf

Air particulate matter (PM) samples were collected from June 2006 to May 2007 for determination chemical elements. PM samples were taken in two size fractions (PM₂.₅ and PM₁₀) with MiniVolume air samplers on rooftops of various buildings (15-25 m above ground) in the city of Riyadh. The samples were subjected to XRF analysis to measure major (Na, Mg, Al, K, Ca, Si, P, S and Fe) and trace elements (Mn, Ni, Cu, Zn, and Ba). The results showed that the PM concentrations were higher for PM₁₀ compared to PM₂.₅, indicating that the major PM source was local dust. Also the spatial distribution with high PM concentrations was observed in the south and southeast of the city and the lowest levels were in the center and northeast of the city. This spatial distribution was attributed to different factors such as wind direction and velocity, emission from cement factories, presence of buildings, trees and paved streets that reduce the amount of dust resuspended into the atmosphere. The air quality of the city was found to range from good to hazardous based on PM₂.₅ and from good to very hazardous based on PM₁₀. The element enrichment factors revealed two element groups according to their changing spatial behavior. The first group showed no significant spatial changes indicating they have the same common source. The second group (mainly S and Ni) exhibited significant changes as expected from anthropogenic inputs. The origin of S is possibly a combination of minerals (CaSO₄) and fossil fuel combustion. The source of Ni is probably from fossil fuel combustion

RushdiAhmedCEOASAirQualityElemental(Tables1-4).pdf

Air particulate matter (PM) samples were collected from June 2006 to May 2007 for determination chemical elements. PM samples were taken in two size fractions (PM₂.₅ and PM₁₀) with MiniVolume air samplers on rooftops of various buildings (15-25 m above ground) in the city of Riyadh. The samples were subjected to XRF analysis to measure major (Na, Mg, Al, K, Ca, Si, P, S and Fe) and trace elements (Mn, Ni, Cu, Zn, and Ba). The results showed that the PM concentrations were higher for PM₁₀ compared to PM₂.₅, indicating that the major PM source was local dust. Also the spatial distribution with high PM concentrations was observed in the south and southeast of the city and the lowest levels were in the center and northeast of the city. This spatial distribution was attributed to different factors such as wind direction and velocity, emission from cement factories, presence of buildings, trees and paved streets that reduce the amount of dust resuspended into the atmosphere. The air quality of the city was found to range from good to hazardous based on PM₂.₅ and from good to very hazardous based on PM₁₀. The element enrichment factors revealed two element groups according to their changing spatial behavior. The first group showed no significant spatial changes indicating they have the same common source. The second group (mainly S and Ni) exhibited significant changes as expected from anthropogenic inputs. The origin of S is possibly a combination of minerals (CaSO₄) and fossil fuel combustion. The source of Ni is probably from fossil fuel combustion

RushdiAhmedCEOASAirQualityElemental(Figures1-8).pdf

Air particulate matter (PM) samples were collected from June 2006 to May 2007 for determination chemical elements. PM samples were taken in two size fractions (PM₂.₅ and PM₁₀) with MiniVolume air samplers on rooftops of various buildings (15-25 m above ground) in the city of Riyadh. The samples were subjected to XRF analysis to measure major (Na, Mg, Al, K, Ca, Si, P, S and Fe) and trace elements (Mn, Ni, Cu, Zn, and Ba). The results showed that the PM concentrations were higher for PM₁₀ compared to PM₂.₅, indicating that the major PM source was local dust. Also the spatial distribution with high PM concentrations was observed in the south and southeast of the city and the lowest levels were in the center and northeast of the city. This spatial distribution was attributed to different factors such as wind direction and velocity, emission from cement factories, presence of buildings, trees and paved streets that reduce the amount of dust resuspended into the atmosphere. The air quality of the city was found to range from good to hazardous based on PM₂.₅ and from good to very hazardous based on PM₁₀. The element enrichment factors revealed two element groups according to their changing spatial behavior. The first group showed no significant spatial changes indicating they have the same common source. The second group (mainly S and Ni) exhibited significant changes as expected from anthropogenic inputs. The origin of S is possibly a combination of minerals (CaSO₄) and fossil fuel combustion. The source of Ni is probably from fossil fuel combustion

Organic acid blend supplementation increases butyrate and acetate production in Salmonella enterica serovar Typhimurium challenged broilers.

The burden of enteric pathogens in poultry is growing after the ban of antibiotic use in animal production. Organic acids gained attention as a possible alternative to antibiotics due to their antimicrobial activities, improved nutrient metabolism and performance. The current study was conducted to evaluate the effectiveness of organic acid blend on broilers cecal microbiota, histomorphometric measurements, and short-chain fatty acid production in Salmonella enterica serovar Typhimurium challenge model. Birds were divided into four treatments, including a negative control, positive control challenged with S. Typhimurium, group supplemented with an organic acid blend, and birds supplemented with organic acid blend and Salmonella challenged. Results illustrate significant differences in feed conversion ratios and production efficiency factor between treatment groups, however, the influence of organic acid supplement was marginal. Organic acid blend significantly increased cecal acetic and butyric acids concentrations when compared to unsupplemented groups and resulted in minor alterations of intestinal bacterial communities

Levels, Sources, and Risk Assessment of Polychlorinated Biphenyls (PCBs) in Soils from Industrial Areas: A Case Study from Saudi Arabia

<p>The objective of this study was to assess the pollution levels, sources, and human health risk of polychlorinated biphenyls (PCBs) in soils of industrial areas of the central and eastern regions of Saudi Arabia. Therefore, the surface soil samples from industrial areas (cement kiln, oil refinery, electric power plant, steel industry, and desalination plant) were collected and analyzed by High-Resolution Gas Chromatography-Mass Spectrometry/Mass Spectrometry-Time of Flight (HRGC-MS/MS-TOF) to quantify the levels of 26 PCBs (including 12 dioxin-like PCBs and 14 indicator-PCBs). The investigated 26 PCBs were detected in all soil samples. The total PCBs concentration (from tri-CBs to hepta-CBs) ranged from 171 to 4892 pg g⁻¹ with an average of 1369 pg g⁻¹ in soils of the central region and of 142–1231 pg g⁻¹ with an average of 302 in soils of the eastern region, showing higher values at cement factory and/or oil refinery sites. Overall, the indicator-PCBs were the main congeners and contributed dominantly to the total mass of PCBs in comparison with the dioxin-like PCB congeners, with the most abundant for PCB-180 in the soil samples of the central region. Among individual dioxin-like PCBs, PCB-126 had the highest average value of the toxicity equivalence (TEQ). The TEQ values of ∑12dioxin-like PCBs did not exceed the Canadian soil quality guidelines of dioxin (4 pg TEQ g⁻¹). Based on human health risk assessment via ingestion, dermal contact, and inhalation, low adverse effects of PCBs could be expected as indicated by lower values of cancer risk (≤10⁻⁶). The principal component analysis indicated that there is a different source of PCBs with similar or different PCB profiles.</p

Characteristics and sources of anthropogenic and biogenic hydrocarbons in sediments from the coast of Qatar.

Surface sediment samples from the coastal zone of Qatar were collected and analyzed to determine the characteristics, and sources of anthropogenic and biogenic hydrocarbons. The main compounds in these surface sediments included n-alkanes, methyl n-alkanoates, diterpenoids, hopanes, steranes, phthalate esters, polycyclic aromatic hydrocarbons (PAHs) and unresolved complex mixture (UCM). Their total concentrations ranged from 18.7±3.7-81.1±7.5ng/g (3.7±0.6-10.4±4.8%) for n-alkanes, 8.3±2.3-51±3.4ng/g (3.0±2.0-5.6±2.0%) for methyl n-alkanoates, 1.8±0.1-10.5±1.0ng/g (1.0±0.5-0.4±0.1%) for diterpenoids, 0.0-79.3±7.4ng/g (0.0-7.9±0.6%) for hopanes, 0.0-32.9±7.9ng/g (0.0-6.5±1.0%) for steranes, 0.7±0.1-36.3±3.4ng/g (0.1±0.1-1.9±3.4%) for phthalates, 0.30±0.2-7.8±0.7ng/g (0.02±0.04-0.42±0.72%) for PAHs, and 38±9-609±57ng/g (38.5±13.4-56.5±13.4%) for UCM. The major sources of these lipids were anthropogenic petroleum residues and plasticizers (80-89%), with lesser amounts from natural higher plants and microbial residues (11-20%). Petroleum residues and plasticizer inputs to the coastal sediments of Qatar likely affect the marine ecosystems and associated species groups as well as shallow coastal nursery and spawning areas