PAH concentrations and exposure assessment from house dust retained in air-conditioning filters collected from Greater Doha, Qatar

Polycyclic aromatic hydrocarbons (PAHs) bound in dust retained in air-conditioning unit filters from 13 households in Greater Doha, Qatar, were quantified using GC–MS spectrometry. The median concentrations of ∑16PAH and ∑7PAH were 218.0 ng g−1 (± 125.3) and 112.1 ng g−1 (± 60.2) dry weight, respectively. Results show that except one sample, three- and four-benzene-ring PAHs were dominant in all dust samples. Phenanthrene, anthracene, pyrene, benzene(a)anthracene, and chrysene were dominant in 12 samples with maximum concentrations of 69.7 ng g−1 (± 24.0), 92.9 ng g−1 (± 28.1), 60.4 ng g−1 (± 14.7), 38.6 ng g−1 (± 7.3), and 14.7 ng g−1 (± 3.5), respectively. Benzo(k)fluoranthene has the most abundance of the quantified PAHs in the dust samples accounting for 19% of the total PAHs. Although Kriging interpolation shows a spatial variation of PAHs from north to south of Greater Doha, the mean concentrations in both directions were statically insignificant. Five samples displayed levels of benzo(a)pyrene (BaP) with maximum and median concentrations at 110.8 ng g−1 and 49.9 (± 28.4) dry weight, respectively. Benzo(a)pyrene equivalent approach (BaPE) was applied to assess carcinogenic exposure, and the resulting values (1.3–116.4 ng g−1) indicate that the levels observed were below the values reported for other countries within the region. Estimated daily ingestion (EDI) rates of PAHs retained in ACU filters were assessed for five age-groups  19 years and were 0.39 (± 0.1), 0.33 (± 0.1), 0.20 (± 0.02), 0.07 (± 0.02), and 0.05 (± 0.01) ng kg−1/day, respectively. Source apportionment estimate indicates PAHs bound in dust retained in ACU filters are originated from pyrogenic sources.Open Access funding provided by the Qatar National Library. We acknowledge QNRF for their continued financial support of NPRP8-202-3-043. We are grateful to the technical staff and management of the chemical analysis laboratory at the Environmental Science Center and Prof Hamad Al Kawari and Mrs., Hajer Al Niami for their support during analysis. Our thanks also go to Mr. Mazen Al Asali and Mrs. Noora Al Shamary for their assistance in the sample analysis. We also are thankful to the families of residents for their participation. Our thanks go to Dr. Jeff Obbard for his support and encouragement in formulating this research. Finally, we are ever grateful to Mark Chatting for his time in reviewing the English language of this article

Polycyclic aromatic hydrocarbons in dust from the indoor environment of Qatar

Polyaromatic Hydrocarbons (PAHs) concentrations in dust trapped on air conditioning unit filters operating in residential and workplace locations in Doha, Qatar were sampled and measured. Fourteen samples were collected and their PAH congener profile were quantified using gas chromatography–mass spectrometry (GC-MS). The results showed that the medians of ΣPAH16, which include seven carcinogenic components (ΣPAH7), were 214.7 ng g− 1 and 129.2 ng g− 1 of dust respectively for the residential samples, and 224.4 ng g− 1 and 137.9 ng g− 1 respectively for dust samples collected in an office workplace environment. Among all samples, benzo (b) fluoranthene (BBF) and benzo (a) pyrene (BAP) were the dominant congeners in both the residential and workplace samples, representing 18.2% and 16.9% of the ΣPAH16, respectively. Factors of correlation were calculated for various PAHs, and showed that lighter molecular weight PAHs have a significant positive correlation with heavier congeners within the residential samples, while workplace samples showed a negative correlation with BAP, Indeno (1,2,3-cd) pyrene (IND), and Dibenz (a,h) anthracene (DBA). Benzo (a) pyrene equivalent (BAPe) was used to assess the risk of human exposure to PAH inhalation. BAPe estimates for residences sampled averaged 0.019 μg g− 1, with a maximum of 0.063 μg g− 1 of dust, while workplace estimates averaged at 0.056 μg g− 1 with a maximum of 0.148 μg g− 1. Source apportionment assessment indicated that most residential and workplace PAHs samples have a pyrogenic origin with few showing evidence of petrogenic origins. All quantified PAHs concentrations and estimated BAPe in Qatar indoor dust samples are well below reported values elsewhere in the world

Spatial variability of summer hydrography in the central Arabian Gulf

The Arabian Gulf is a very significant ocean body, which hosts more than 55% of the oil reserves of the world and produces about 30% of the total production, and thus, it is likely to face high risk and adverse problems by the intensified environmental stressors and severe climatic changes. Therefore, understanding the hydrography of the Gulf is very essential to identify various marine environmental issues and subsequently, developing marine protection and management plans. In this study, hydrography data collected at 11 stations along 3 linear transects in the early summer of 2016 were analyzed. The physicochemical parameters exhibited apparent variations along each transect, both laterally and vertically, connected to stratification, formation of different water masses and excessive heating. The temperature and salinity decreased laterally from nearshore to offshore, while layered density structures were identified in the offshore regions. The pH, dissolved oxygen (DO) and chlorophyll fluorescence (Fo) exhibited distinct horizontal and vertical variations. The observed pH is within the normal ranges, indicating that seawater acidification may not be a threat. The highest DO (6.13–8.37 mg/l) was observed in a layer of 24-36 m water depth in the deeper regions of the central transect

Target gastropods for standardizing the monitoring of tar mat contamination in the Arabian Gulf

This study proposes a standardization process for the monitoring the level of tar mat contamination in the Arabian Gulf. In the study, we selected target gastropod species and evaluated the ecological and ecotoxicological effects of tar mats on their populations, the bioaccumulation of heavy metals, and these species’ potential as bioindicator taxa for tar mat-associated heavy metals. The study was carried out at two sites on the Qatar coast on shoreline rocks, both of which have areas of tar mat coverage and areas without tar mats. The species selected as representative species for the ecoregion were the endemic Clypeomorus bifasciata persica (Houbrick, 1985) in the intertidal zone and the Echinolittorina arabica (El Assal, 1990) in the supratidal zone. Both are grazers and are niche restricted to hard substrates and daily scraping/grazing on the tar mat deposition zone of the shorelines. The key heavy metal indicators chosen were As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni and Zn, and the gastropod species were divided into classes according to their size. Tar mat presence was found to negatively affect both the overall population size of Clypeomorus and different size classes, and lead to high levels of assimilation of heavy metals. Tar mat presence also negatively affected different size classes of Echinolittorina where large sizes were found to be most significantly affected. The results also demonstrated that Cu and Ni are the heavy metals most associated with tar mat contamination of this kind. Overall, our results confirmed that grazer gastropods are good bioindicators of tar mat-associated contaminants in shoreline ecosystems. Our study provides the database on the heavy metal contamination of the proposed target gastropods, and offers information that will be relevant for further monitoring and comparisons among threatened coastal areas in the Arabian Gulf.This research was supported by the Qatar Petroleum through the project of QU (QUEX-ESC-QP-TM-18/19)

Observed variability in physical and biogeochemical parameters in the central Arabian Gulf

In situ measurements of physical and biogeochemical variables were conducted along a transect in the Exclusive Economic Zone (EEZ) of Qatar during late summer (September 2014) and winter (January 2015) to investigate their vertical, spatial and temporal variability. The study reveals that the water column is characterized by strong stratification during late summer in the deepest station, where the water depth is around 65 m and the surface to bottom temperature variation is around 9.1°C. The water column is vertically homogeneous during winter due to surface cooling and wind mixing. The surface to 23 m water column is characterized by ample dissolved oxygen (DO) during late summer and winter in the offshore regions, however, relatively low DO is found during late summer due to weak mixing and advection under weak winds and currents. Dissolved oxygen drops to hypoxic levels below the summer thermocline, and the winter high DO layer extends up to the bottom. Chlorophyll-a (Chl-a) is relatively high during late summer in the offshore region, while that in the nearshore regions is very low, which is linked to the anthropogenic stresses from the central east coast of Qatar. The results identified in this study fill an essential gap in the knowledge of regional primary production dynamics.Environmental Science Center (ESC) & Department of Biological and Environmental Sciences (DBES), Qatar University (QU

Geochemical composition of dust from Qatar peninsula

Atmospheric dust samples have been collected from different areas in Qatar and analyzed for major and trace element composition. This region of the Arabian Gulf represents an area largely affected by dust from natural and anthropogenic sources. Twenty one samples were collected during 2014 and 2015 from Al-Khor, Katara, Sealine, Al-Waab, and Qatar University by passive and active sampling techniques. Some bulk samples were collected during the massive megastorm that occurred in April 2015. Back trajectories were determined for each sample set using the NOAA HYSPLIT model over a 50 hour time interval. Samples were equally divided between northerly (n=12; northern Saudi Arabia, Kuwait or Iraq) and southerly (n=8; SE Saudi Arabia, United Arab Emirates and Oman) sources. One sample is expected to originate from westward, in Saudi Arabia. There is more variability noticed in source locations throughout the winter months (October to March), with more of them coming from the south (9 times) compared to summer months (April to September) for twice only. Dust samples were microwave-assisted, total acid digested (HF+HCl+HNO3) and oxidized with H2O2 before analyses were conducted by ICP-OES. Only 12 out of 23 elements (Al, Ca, Fe, K, Mg, Na, Ag, As, Ba, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sr, V, Zn, P) of the Qatari dust samples were enriched relative to Upper Continental Crust (UCC). Calcium was especially enriched to a level of 400% relative to UCC. About 33% of the total sample mass was CaCO3, reflecting the composition of surface rocks in the source areas. Of the elements typically associated with anthropogenic activity, Ag, Ni, and Zn were the most enriched relative to UCC, with enrichment factors of 182%, 233%, and 209%, respectively. Other metals like Pb and V were not significantly enriched, with enrichment factors not exceeding 25% and 3%, respectively. Major elements (Al, Mn and Fe) were depleted relative to UCC due to the strong enrichment of CaCO3, with enrichment factors of -58%, -35% and -5%, respectively. Samples with northern and southern origins were separated to investigate if the elemental composition could be used to identify source/origin. Only three elements were observed to have a statistical difference. Pb and Na were higher in the samples collected from the south while Cr was higher in those from the north. This study aims to investigate present-day geochemistry of dust particles and its effect on the marine environment of the Arabian Gulf. The geochemical composition of dust is essential component for correcting lithogenic input to water column suspended matter samples.qscienc

Trace element composition of size-fractionated suspended particulate matter samples from the Qatari Exclusive Economic Zone of the Arabian Gulf: the role of atmospheric dust

We analyzed net-tow samples of natural assemblages of plankton, and associated particulate matter, from the Exclusive Economic Zone (EEZ) of Qatar in the Arabian Gulf. Size-fractionated suspended particles were collected using net tows with mesh sizes of 50 and 200 μm to examine the composition of small- and large-size plankton populations. Samples were collected in two different years (11 offshore sites in October 2012 and 6 nearshore sites in April 2014) to examine temporal and spatial variabilities.We calculated the excess metal concentrations by correcting the bulk composition for inputs from atmospheric dust using aluminum (Al) as a lithogenic tracer and the metal=Al ratios for average Qatari dust. Atmospheric dust in Qatar is depleted in Al and enriched in calcium (Ca), in the form of calcium carbonate (CaCO3), relative to the global average Upper Continental Crust (UCC). To evaluate the fate of this carbonate fraction when dust particles enter seawater, we leached a subset of dust samples using an acetic acid–hydroxylamine hydrochloride (HAc–HyHCl) procedure that should solubilize CaCO3 minerals and associated elements. As expected, we found that Ca was removed in Qatari dust; however, the concentrations (ppm) for most elements actually increased after leaching because the reduction in sample mass resulting from the removal of CaCO3 by the leach was more important than the loss of metals solubilized by the leach. BecauseQatar National Research Fund (QNRF) under the National Priorities Research Progra

Population Genetic Structure and Gene Expressions Patterns of the Copepod Calanus finmarchicus in the North Atlantic Ocean

Calanus finmarchicus (Copepoda, Calanoida) is an ecologically important copepod species that is ubiquitous in coastal and open waters of the North Atlantic Ocean. Basin-scale and small-scale spatial genetic variation in C. finmarchicus was examined among and within geographic population samples obtained from the Northwest, North Central, and Northeast Atlantic gyres during 2005. Allelic variation at 24 Single Nucleotide Polymorphisms (SNPs) at selected nuclear loci (CS, hsp70, and AMPK) suggested large-scale differentiation involving two to four distinct gyre populations, reflecting persistent barriers to gene flow associated with entrainment in ocean gyres. Barents Sea population was found to be distinctive. The analyses also revealed small, but significant, differentiation among 10 areas examined within gyres, potentially reflecting ecologically important, short-term variation driven by variation in life history traits. Temporal variation in Northwest Atlantic populations of C. finmarchicus was examined using time-series collections from within the Gulf of Maine, which is subject to major environmental variation. This study examined interannual variation of selected genetic characteristics for C. finmarchicus associated with a dramatic decline in abundances in 1998 following a negative NAO anomaly in 1996. SNPs in the citrate synthase (CS) encoding gene were analyzed for C. finmarchicus samples collected during 1997, 1998 and 1999, and compared with samples obtained from 2003, 2004 and 2005. The results indicated the presence of significant variation in SNP allele and genotype frequencies among years, and the distinctiveness of 1999 samples, possibly as a result of advective import of genetically divergent copepods from adjacent regions. The molecular mechanisms underlying important physiological processes of the species were examined through differential gene expression analysis for copepodite stage 5 (CV) and female C. finmarchicus obtained from surface and deep waters in Gulf of Maine, by using an Expressed Sequence Tag (EST) microarray. Up-regulation of genes involved in cell division, protein synthesis and mating were remarkable in deep females and CVs. Up-regulation of genes related to cellular homeostasis, circadian behavior and nervous system development were pronounced in surface females. Lastly, up-regulation of genes related to muscle development and protein catabolism were indicated for deep CVs compared to deep females

Population Genetic Structure and Gene Expressions Patterns of the Copepod Calanus finmarchicus in the North Atlantic Ocean

Calanus finmarchicus (Copepoda, Calanoida) is an ecologically important copepod species that is ubiquitous in coastal and open waters of the North Atlantic Ocean. Basin-scale and small-scale spatial genetic variation in C. finmarchicus was examined among and within geographic population samples obtained from the Northwest, North Central, and Northeast Atlantic gyres during 2005. Allelic variation at 24 Single Nucleotide Polymorphisms (SNPs) at selected nuclear loci (CS, hsp70, and AMPK) suggested large-scale differentiation involving two to four distinct gyre populations, reflecting persistent barriers to gene flow associated with entrainment in ocean gyres. Barents Sea population was found to be distinctive. The analyses also revealed small, but significant, differentiation among 10 areas examined within gyres, potentially reflecting ecologically important, short-term variation driven by variation in life history traits. ^ Temporal variation in Northwest Atlantic populations of C. finmarchicus was examined using time-series collections from within the Gulf of Maine, which is subject to major environmental variation. This study examined interannual variation of selected genetic characteristics for C. finmarchicus associated with a dramatic decline in abundances in 1998 following a negative NAO anomaly in 1996. SNPs in the citrate synthase (CS) encoding gene were analyzed for C. finmarchicus samples collected during 1997, 1998 and 1999, and compared with samples obtained from 2003, 2004 and 2005. The results indicated the presence of significant variation in SNP allele and genotype frequencies among years, and the distinctiveness of 1999 samples, possibly as a result of advective import of genetically divergent copepods from adjacent regions.^ The molecular mechanisms underlying important physiological processes of the species were examined through differential gene expression analysis for copepodite stage 5 (CV) and female C. finmarchicus obtained from surface and deep waters in Gulf of Maine, by using an Expressed Sequence Tag (EST) microarray. Up-regulation of genes involved in cell division, protein synthesis and mating were remarkable in deep females and CVs. Up-regulation of genes related to cellular homeostasis, circadian behavior and nervous system development were pronounced in surface females. Lastly, up-regulation of genes related to muscle development and protein catabolism were indicated for deep CVs compared to deep females.