Baseline concentrations and distributions of Polycyclic Aromatic Hydrocarbons in surface sediments from the Qatar marine environment.

Coastal sediments in marine waters of Qatar have the potential of being contaminated by Polycyclic Aromatic Hydrocarbons (PAHs) due to extensive petroleum exploration and transportation activities within Qatar's Marine Exclusive Economic Zone. In this study, the concentration and distribution of sixteen PAHs classed as USEPA priority pollutants were measured in sediments from the eastern Qatari coast. PAHs were recovered from sediments via accelerated solvent extraction and then analyzed using Gas Chromatography-Mass Spectrometry. Total concentrations of the PAHs were in the range of 3.15-14.35µg/kg, and the spatial distribution of PAHs is evaluated in the context of sediment total organic content, depth and the grain size together with and the proximity of petroleum exploration and transportation activities. The data show that the concentrations of PAHs within the study area were in the low-range, suggesting a low risk to marine organisms and limited transfer of PAHs into the food web.

A modified technique for field measurements of dry deposition fluxes of polychlorinated biphenyls in tropical regions.

This report focused on the development of a technique to measure dry deposition fluxes of PCBs in tropical environments. Temperature resistant double-adhesive tape has been used as a new surrogate surface for collection of deposited PCBs. The new technique includes the measurement of field blanks for the entire sampling period. A sonication-assisted extraction procedure has been validated for the extraction of PCBs from the tape. The new technique has been used in the field for a period of 4 months in the tropical region of Singapore. The average dry deposition flux measured for total PCBs was 15.3 ng m(-2) day(-1) and, on a global scale, this can be considered to be low.

Polybrominated diphenyl ethers in house dust in Singapore.

The use of polybrominated diphenyl ethers (PBDEs) as flame retardants in Singapore is not strictly regulated; therefore these compounds can be readily found in furniture, electronic devices, and building materials. This study was the first of its kind to be conducted in Singapore to measure concentrations of PBDEs in house dust. Samples were collected from 31 homes in various locations across the island-state of Singapore, and a total eight PBDEs congeners were measured. PBDEs were detected in all 31 dust samples and the number of BDE congener detected per home ranged between 3 and 8. The most abundant BDE congeners found were BDE 47, 99 and 209, with a median value of 20 ng g(-1) dust, 24 ng g(-1) dust and 1000 ng g(-1) dust, respectively. BDE 209 contributed 88% to the median of all the congeners, and BDE 47 and 99 contributed 1.8% and 3.5%, respectively. Different congener profiles were observed between this and studies conducted elsewhere, which is consistent with the use of different commercial PBDE around the world. No significant correlations between PBDE dust levels and residential characteristics (number of TVs and computers, floor area or flooring material) were observed. The daily intake of PBDEs via the inhalation pathway was estimated. House dust may be regarded as the most important exposure route of PBDEs for children.

Selected organochlorine pesticide and polychlorinated biphenyl residues in house dust in Singapore.

Although the use of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) has been prohibited in Singapore since 1980, OCPs and PCBs still can be detected in the environment and represent a potential threat to public health. In this study, OCPs and PCBs were measured in house dust samples collected from 31 homes across the island-state of Singapore. Organochlorine pesticides, such as hexachlorocyclohexanes (HCHs), chlordanes and dichlorodiphenyltrichloroethanes (DDTs) were tested, with a range of

Atmospheric wet deposition of PAHs to the sea-surface microlayer.

Sea-surface microlayer (SML) and subsurface seawater samples (SSW) collected from Singapore's coastal environment were analyzed for 14 polycyclic aromatic hydrocarbons (PAHs) in the dissolved (DP) and suspended particulate phase (SPM). Samples were collected prior to and after rainfall events to ascertain the contribution of wet atmospheric deposition of PAH enrichment to the SML. The concentration ranges of summation operatorPAHs in the SML before rain and after wet deposition were 2.6-46.2 ngL(-1) and 4.3-278.0 ngL(-1), respectively, for the DP and 3.8-31.4 ngL(-1) and 12.8-1280 ngL(-1), respectively, for the SPM. Load factors (i.e. concentration after wet deposition relative to before wet deposition) of the atmospheric wet deposition for DP and SPM ranged from 1.4 to 42.9 and 1.2 to 337, respectively. This study provides the first data on PAH concentration, enrichment (i.e. concentration of PAHs in SML relative to subsurface water) and load factors in the SML before and after wet deposition to the ocean surface.

Microplastics in coastal environments of the Arabian Gulf.

Eight sandy beaches along the coastline of Qatar and four sea surface stations on the eastern coast, adjacent to Doha Bay, were surveyed between December 2014 and March 2015. Microplastics, mainly low density polyethylene and polypropylene, were found in all samples of sediments and seawater. Blue fibers, ranging between 1 and 5mm, were the dominant type of particle present. Abundances on the sea surface varied between 4.38×104 and 1.46×106particles·km-2, with the highest values being consistently found 10km offshore, suggesting the presence of a convergence zone. No significant temporal variability was detected for sea surface samples. The concentration of microplastics in intertidal sediments varied between 36 and 228particlesm-2, with no significant differences among the 8 beaches examined. These results show the pervasiveness of microplastic pollution in coastal environments of the Arabian Gulf. Potential local sources and sinks for microplastics are discussed.

Chlorinated paraffins: a review of analysis and environmental occurrence.

Chlorinated paraffins (CPs), as technical mixtures of polychlorinated alkanes (PCAs), are ubiquitous in the environment. CPs tend to behave in a similar way to persistent organic pollutants (POPs), leading several countries to impose regulations on the use of CPs. In this article, we review the literature on the properties of CPs, the current analytical tools available to determine CPs in various types of environmental matrices, and concentrations found in the environment. In particular, concentrations of CPs in environmental compartments including air, water, sediments, biota, human food products and human tissues are summarized. Priorities for future research are: improvements in analytical methodologies (reducing the complexity of the analysis, producing reference materials and performing interlaboratory studies); determining background levels of chlorinated paraffins in the environment and human populations (this question should be answered using quality assured analytical tools allowing the intercomparison of data); and investigating the sources of CPs to the environment and to humans.

Levels of persistent organic pollutant residues in human adipose and muscle tissues in Singapore.

Persistent organic pollutants (POPs), due to their persistence and bioconcentration in lipid-rich tissue, bioaccumulate in food chains, resulting in elevated concentrations in humans. This study was performed to determine and compare levels of POPs in human adipose and muscle tissues in the female population of Singapore. In total, 36 human adipose tissues and 8 human muscle tissues were collected from volunteer expectant mothers admitted to the National University Hospital Singapore for cesarean section delivery between August 2003 and January 2005. Samples were analyzed using a validated and quality-assured gas chromatography-mass spectroscopy (GC-MS) method in conjunction with microwave-assisted extraction (MAE). Analytes recoveries from certified reference materials, that is, IRMM-446 (polychlorinated biphenyls [PCBs] in pork fat) and BCR-430 (organochlorine pesticides in pork fat), were between 70 and 130%, indicating reliable analytical precision for this methodology. MAE efficiency for polybrominated diphenyl ethers (PBDEs) was compared to Soxhlet extraction (SE) efficiency and yielded comparable results (variation < 13%). Analytical results indicate that p,p'-DDE of the dichlorodiphenyltrichloroethane (DDT) residues group is the predominant compound in adipose tissue, followed by beta-hexachlorocyclohexane (beta-HCH) among HCH isomers, then hexachlorobenzene (HCB) compound and specific PCB and PBDE congeners. Among the 36 adipose tissues, the lipid contents in adipose tissue were in the range of 60% to 95%, while in the 8 muscle tissues, lipids were undetectable. However, the profile of PCBs and pesticide residues present in muscle tissues were similar to those in adipose tissues.

Persistent organic pollutants and adverse health effects in humans.

Persistent organic pollutants (POPs) are synthetic chemicals that have an intrinsic resistance to natural degradation processes, and are therefore environmentally persistent. The introduction of POPs into the environment from anthropogenic activities resulted in their widespread dispersal and accumulation in soils and water bodies, as well as in human and ecological food chains, where they are known to induce toxic effects. Due to their ubiquity in the environment and lipophilic properties, there is mounting concern over the potential risks of human exposure to POPs. This has led to the establishment of monitoring programs worldwide to determine prevailing levels of POPs in the population and to investigate the adverse health risks associated with background exposure. This article reviews the state of knowledge regarding residual levels of POPs in human adipose tissue worldwide, and highlights research data for POPs in the environment and human maternal adipose tissue in Singapore. Although concentrations are comparable to those observed elsewhere, longer term monitoring of a larger cross section of the population is warranted in order to establish temporal trends and potential risks to human health.

The role of the sea-surface microlayer in the air-sea gas exchange of organochlorine compounds.

Simultaneous measurements of organochlorine compounds (OCs) in seawater, the sea-surface microlayer and the atmosphere were conducted in June-July 2004 in the coastal marine environment of Singapore. Together, these measurements represent the first data on the flux of OCs between the ocean and atmosphere reported in the scientific literature that take into account the implication of the sea surface microlayer (SML) as a controlling boundary layer for the exchange of OCs. The average fluxes of SigmaPCBs and SigmaHCHs were 127.5 and -32.8 ng m(-2) day(-1) respectively using a modified two-layer model (negative flux indicates adsorption by the ocean). The average fluxes using a conventional approach, ignoring the SML as boundary layer (classical two-layer model), were 67.2 and -43.1 ng m(-2) day(-1) for SigmaPCBs and SigmaHCHs, respectively. However, the maximum difference in the flux calculation between the two approaches was up to 15-fold for individual compounds at high enrichment in the SML. It is shown that the SML plays an important role in the control of air-sea gas exchange of OCs, particular under a low prevailing wind regime and with an enrichment of OCs in the SML. The physical and chemical properties of OCs are critical factors in the control of the air-sea gas exchange process, and the effect of the SML on this process is more significant for more hydrophobic OCs.

Distribution of organochlorine compounds in the sea-surface microlayer, water column and sediment of Singapore's coastal environment.

Hexachlorocyclohexanes (HCHs), dichlorodiphenylethanes (DDTs) and 38 PCB congeners were determined in the water column (sea-surface microlayer, subsurface, mid-depth and bottom water) and sediments from Singapore's coastal environment. The concentration ranges for summationHCHs, summationDDTs and summationPCBs in the seawater dissolved phase (DP) were 101-6110 (mean 1833), <5-405 (mean 76) and 60-6979 (mean 1611)pg/l, respectively. The concentration ranges for summationHCHs, summationDDTs and summationPCBs in the suspended particulate matter (SPM) were 26-2395 (mean 243), <5-124 (mean 19) and 38-3793 (mean 715) pg/l, respectively. Concentration levels in sediments ranged between 521 and 1758 (mean 1094), 50 and 290 (mean 88) and 339 and 1356 (mean 858) pg/g for summationHCHs, summationDDTs and summationPCBs, respectively. It was shown that the interfaces of the sea-surface microlayer (SML) and near bottom water are important compartments for the distribution of organochlorine compounds (OCs) in the water column. In comparison with data from China, the concentration levels in the water column and sediments of Singapore can be considered as low, but the reported levels were higher compared to available data from Europe.

Occurrence and distribution of polybrominated diphenyl ethers (PBDEs) in the dissolved and suspended phases of the sea-surface microlayer and seawater in Hong Kong, China.

This study reports the first data on the concentration and distribution of polybrominated diphenyl ethers (PBDEs) in the sea-surface microlayer (SML), and their enrichment relative to bulk seawater, for coastal waters in the marine environment of Hong Kong, China. Samples were collected in March 2005 at five sample locations and analysed for eight congeners of primary interest, i.e. BDE 28, 47, 99, 100, 153, 156, 183 and 209. Concentration ranges of summation operatorPBDE in the dissolved phase (DP, defined as sum of truly dissolved and colloidal phase) and suspended particulate matter (SPM) of seawater were 31.1-118.7 pg/l (mean 70.7 pg/l), and 25.7-32.5 pg/l (mean 28.1 pg/l), respectively. Concentrations in the SML were generally higher by factor of 1.3-3.6 in the DP (concentration range from 40.2 to 228.2 pg/l, mean 149.2 pg/l) and by 0.3-2.1 in the SPM (concentration range 8.1-69.1 pg/l, mean 38.2 pg/l). Concentrations of PBDEs were general low and below detection limits in samples of an oceanic character and highest in the sheltered waters of Victoria Harbour. The congeners BDE 28, 47, 100 and 183 were most abundant, where BDE 209 was detected only in trace amounts. It is suggested that Hong Kong's marine waters show relatively low levels of PBDE contamination, and these compounds may originate from the disposal of electronic waste in southern China, as well as untreated discharge of wastewater locally.

Distribution of organochlorines in the dissolved and suspended phase of the sea-surface microlayer and seawater in Hong Kong, China.

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in the dissolved and suspended particulate phase in the sea-surface microlayer (SML) and subsurface water (SSW) collected from Hong Kong's coastal environment. The concentration ranges (pg/L) for summation sigmaHCHs, summation sigmaDDTs and summation sigmaPCBs in the SSW dissolved phase (DP i.e. sum of truly dissolved and colloidal phase) were 409-940 (mean 602), 774-5583 (mean 1908) and 266-433 (mean 278), respectively. The concentration ranges (pg/L) for summation sigmaHCHs, summation sigmaDDTs and summation sigmaPCBs in SSW suspended particulate matter (SPM) were <5-85 (mean 59), 358-1369 (mean 787) and 85.6-273 (mean 172), respectively. The enrichment factor of PCBs and OCPs in the SML varied between 1.1 and 4.5 for the DP, and 0.4-8.2 for the SPM. The distribution of contaminants between DP and SPM in both the SML and SSW indicates that particulate matter plays an important role in the distribution and fate of DDTs and PCBs, but not for HCH isomers. The Pearl River Estuary is likely to be a major source of contaminants transported to Hong Kong.

Prevalence of microplastics in the marine waters of Qatar.

Microplastics are firmly recognized as a ubiquitous and growing threat to marine biota and their associated marine habitats worldwide. The evidence of the prevalence of microplastics was documented for the first time in the marine waters of Qatar's Exclusive Economic Zone (EEZ). An optimized and validated protocol was developed for the extraction of microplastics from plankton-rich seawater samples without loss of microplastic debris present and characterized using Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy. In total 30 microplastic polymers have been identified with an average concentration of 0.71particlesm(-3) (range 0-3particlesm(-3)). Polypropylene, low density polyethylene, polyethylene, polystyrene, polyamide, polymethyl methacrylate, cellophane, and acrylonitrile butadiene styrene polymers were characterized with majority of the microplastics either granular shape, sizes ranging from 125µm to 1.82mm or fibrous with sizes from 150µm to 15.98mm. The microplastics are evident in areas where nearby anthropogenic activities, including oil-rig installations and shipping operations are present.

Analysis of persistent organic pollutants in marine sediments using a novel microwave assisted solvent extraction and liquid-phase microextraction technique.

A simple and novel analytical method for quantifying persistent organic pollutants (POPs) in marine sediments has been developed using microwave assisted solvent extraction (MASE) and liquid-phase microextraction (LPME) using hollow fibre membrane (HFM). POPs studied included twelve organochlorine pesticides (OCP) and eight polychlorinated biphenyl (PCB) congeners. MASE was used for the extraction of POPs from 1 g of sediment using 10 ml of ultrapure water at 600 W for 20 min at 80 degrees C. The extract was subsequently subjected to a single step LPME-HFM cleanup and enrichment procedure. Recovery varied between 73 and 111% for OCPs; and 86-110% for PCBs, and exceeded levels achieved for conventional multi-step Soxhlet extraction coupled with solid-phase extraction. The method detection limit for each POP analyte ranged from 0.07 to 0.70 ng g(-1), and peak areas were proportional to analyte concentrations in the range of 5-500 ng g(-1). Relative standard deviations of less than 20% was obtained, based on triplicate sample analysis. The optimized technique was successfully applied to POP analysis of marine sediments collected from the northeastern and southwestern areas of Singapore's coastal environment.

Determination and occurrence of polybrominated diphenyl ethers in maternal adipose tissue from inhabitants of Singapore.

Polybrominated diphenyl ethers (PBDEs), as a specific group of brominated flame retardants (BFR), are used in a variety of consumer products including electronics and household furnishings. In recent years, a marked increase in the levels of PBDEs in human biological tissues and fluids, especially breast milk, has been reported in several countries. However, few data are available from countries in the Asia-pacific region, including Singapore. This study presents a validated method procedure and the first available data of the concentrations of PBDE congeners: PBDE-47 (2,2,4,4-Tetrabromodiphenyl ether), PBDE-99 (2,2',4,4',5-Pentabromodiphenyl ether), PBDE-100 (2,2',4,4',6-Pentabromodiphenyl ether), PBDE-153 (2,2',4,4',5,5'-Hexabromodiphenyl ether), PBDE-154 (2,2',4,4',5,6'-Hexabromodiphenyl ether) in maternal adipose tissue collected from inhabitants of Singapore. Microwave-assisted extraction (MAE) of PBDEs spiked adipose tissues coupled with GC-MS analysis achieved comparable recoveries to a conventional Soxhlet Extraction (SE) procedure of between 70 and 130%. MAE also yielded comparable precision data (variance less than 13%) relative to the SE procedure. Spiked Carbon-13 PBDE congeners were also used as surrogates for MAE quality assurance and confirmed the efficiency of the procedure. PBDE congeners were detected in all of 16 maternal adipose tissues collected in Singapore, where levels were comparable to available data from Belgium.

Strategic environmental assessment in Hong Kong.

This review examines the development and application of strategic environmental assessment (SEA) process in the planning framework of Hong Kong. Two strategic planning case studies are evaluated within the context of SEA, namely the Territorial Development Strategy Review (TDS Review) and the Third Comprehensive Transport Study (CTS-3). Rapid population growth and urbanisation in Hong Kong, coupled with a historic lack of planning controls and inherent conflicts between government departments have been major obstacles to achieving sustainable development in the territory. Despite these challenges, Hong Kong was one of the first Asian countries to apply SEA to major development plans, where the implementation of the 'SUSDEV 21' study on sustainable development has demonstrated the government's commitment towards integrated environmental protection. The application of SEA has provided decision-makers with key information on potential environment impacts arising from proposed developments, resulting in greater accountability and transparency in the decision-making process. SEA in Hong Kong has also prompted an increased level of environmental awareness and co-operation between government departments and agencies responsible for the management of Hong Kong's natural and urban environments. However, the application of SEA in Hong Kong continues to have notable limitations. SEA needs to evolve beyond its current sectoral application to examine ways in which development decisions can not only pre-empt and prevent environmental damage, but also positively enhance and restore existing natural resources. Current land use plans and transportation strategies still largely determine the pattern of development in the near future without adequate longer-term environmental cost-benefit analysis. Sustainable development includes environmental, social and economic considerations, and these inter-related elements need be suitably balanced. SEA is not a means to obstruct development in Hong Kong, but should be recognised for its inherent socio-economic and ecological value, and fully integrated with the decision-making process. Whilst it is admirable that Hong Kong has taken positive steps in this direction, it is now an opportune moment for the government to have the foresight and tenacity to create a sustainable development framework for Hong Kong into the future.

Persistent organic pollutants and heavy metals in typical seafoods consumed in Singapore.

In this study, the levels of several heavy metals and persistent organic pollutants (POPs) were measured in the edible portions of 20 different seafood types consumed in Singapore (2 < n < 12). The mean heavy metal concentrations among the seafood types ranged from below detection limits (BLD) to 14.2 microg/g wet weight (ww) for As (shark), to 0.50 microg/g ww for Cd (kunning), to 25.5 microg/g ww for Cu (gray prawn), to 0.58 microg/g ww for Hg (eel), and to 1.21 microg/g ww for Pb (salmon). Chlordane, polychlorinated biphenyls (PCBs), and p, p'-DDT [2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane] and its related metabolites (sum noted as DDTs) were the main POPs found among the seafood types, with highest concentrations in salmon fillets and green mussels. Polybrominated diphenyl ether (PBDE) concentrations in salmon fillets (2.75 ng/g ww) were one order of magnitude lower than the highest concentration of PCBs (28.5 ng/g ww). The mean daily intake of contaminants from seafood was calculated for the general population of Singapore. Daily intakes of heavy metals and POPs from seafood are below the oral reference dose set by the U.S. Food and Drug Administration (FDA), except for As, although our study did not characterize the species of As present. Daily intake of As, DDTs, heptachlor, and PCBs in seafood exceeded the conservative cancer benchmark concentrations set by the U.S. Environmental Protection Agency (EPA), suggesting that a significant number of people are potentially at risk in Singapore over a lifetime from seafood consumption.

Effect of cooking on the loss of persistent organic pollutants from salmon.

Recent studies have raised concern over the presence of high levels of persistent organic pollutants (POPs) in farmed fish relative to wild specimens of the same species, particularly salmon. Although cooking is known to reduce the burden of POPs in fish, the mechanisms of loss/degradation are not clearly understood. This study investigated the loss of POPs, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), p,p'-DDT [2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane] and its related metabolites (sum noted as DDTs), and chlordane congeners, from salmon (Salmo salar) steaks when subjected to baking, boiling, frying, or microwave cooking. Ranges in the raw flesh were 25.1-62.9 ng/g wet weight (ww) for PCBs, 2.5-7.6 ng/g ww for PBDEs, 2.4-5.3 ng/g ww for chlordanes, and 17.5-43.8 ng/g ww for DDTs. Analysis of raw steaks from along the fish body revealed a significant variation of POP concentrations along the fish body, with higher concentrations at the head end than the tail, with a peak in the central section. After cooking, levels of POPs decreased in salmon steak with an average loss of 26 +/- 15% relative to the initial POP load in the raw steak. The removal of the skin from the cooked salmon steak resulted in a further average loss of 9 +/- 3%. The loss of POPs did not differ significantly between cooking methods. Losses of POPs were significantly and linearly correlated with the losses of lipid during cooking, suggesting removal of lipids is the critical factor for POPs reduction in cooked fish. Cooking of raw fish contaminated with POPs can therefore be expected to reduce the consumption exposure risk to human health.

Organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in Singapore's coastal marine sediments.

Persistent organic pollutants (POPs) are ubiquitous pollutants in the marine environment, particular in coastal areas affected by industry and shipping traffic. POPs are known for their recalcitrance and toxicity in the environment, and there is increasing concern over their global distribution and impact upon wildlife. Marine surface sediment samples taken within 6 km of the coastline of Singapore were analyzed to determine prevailing concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyl (PCBs) and polybrominated diphenyl ethers (PBDEs). Total PCB concentrations varied widely from 1.4 to 329.6 ng/g (average 73.9 ng/g), where high concentrations were detected at sample locations closest to industrial areas with intensive shipping traffic. Total DDT concentrations ranged from 2.2 to 11.9 ng/g (average 6.7 ng/g) and were lower than the concentration range of 3.3-46.2 ng/g measured for total HCH (average 18.1 ng/g). Ratios of DDT/(DDE+DDD) in sediments do not indicate recent inputs of DDT into Singapore's marine environment, but high concentrations of alpha-HCH and gamma-HCH show evidence for the usage of HCHs in Southeast Asia. Peak concentrations of cis- and trans-Chlordane were 10 ng/g. Among the PBDE congeners BDE 47, 99, and 100 only BDE 47 could be detected at a range of 3.4-13.8 ng/g (average 6.2 ng/g). The levels of OCPs, PCBs and PBDEs were compared to available data for other countries in Asia, and indicated relatively moderate levels of contamination. Peak concentrations of PCBs, HCH isomers, Chlordane, Heptachlor, Heptachlor epoxide and Dieldrin have the potential to induce ecotoxicological impacts based on levels specified in the sediment quality standards of the USEPA and Canadian Council of Ministers of the Environment.