Environmental Sample Stability for Pharmaceutical Compound Analysis: Handling and Preservation Recommendations.

Efficient and resilient techniques for handling samples are essential for detecting pharmaceutical compounds in the environment. This study explores a method for preserving water samples during transport before quantitative analysis. The study investigates the stability of 17α-ethynylestradiol (EE2), acetaminophen (ACM), oxytetracycline (OTC), sulfamethoxazole (SMX), and trimethoprim (TMP) after preconcentration within solid-phase extraction (SPE) cartridges. Through various experiments involving different holding times and storage temperatures, it was determined that four pharmaceutical compounds remained stable when stored for a month at 4°C and for six months when stored at -18°C in darkness. Storing these compounds in SPE cartridges at -18°C seemed effective in preserving them for extended periods. In addition, ACM, TMP, OTC, EE2, and SMX remained stable for three days at room temperature. These findings establish guidelines for appropriate storage and handling practices of pharmaceutical compounds preconcentrated from aqueous environmental samples using SPE.

Passive sampling of chlorinated paraffins by silicone: Focus on diffusion and silicone-water partition coefficients.

Short-chain chlorinated paraffins (SCCPs) are under regulation through the European Water Framework Directive and were recently classified as POPs. Consecutively, the increasing use of middle-chain chlorinated paraffins (MCCPs) becomes of growing concern. Knowledge on the occurrence of chlorinated paraffins (CPs) is still scarce particularly in water phase. To achieve sufficient method sensitivity, the passive sampling approach, acting as a relevant alternative to usual grab sampling, has been considered only very recently for the monitoring of CPs in water. The present work aimed at determining the diffusion coefficients in silicone (Ds) and the silicone-water partition coefficients (Ksw) of various CP groups, having different chlorine contents and carbon chain lengths, in four commercial CP mixtures. Log Ds (-10.78 to -10.21) was found to vary little and to be high for the groups of CPs studied. Thus, their uptake in silicone is controlled by the water boundary layer, which allows to consider the release of performance and reference compounds for in-field estimation of the sampling rate. Moreover, CPs partitioned strongly towards silicone rubbers. Both the chlorination degree and the carbon chain length of CPs cause large uncertainties in the partitioning between silicone and water (log Ksw between 4.85 and 6.30), indicating that instead of an average value, differentiated Ksw should be used to estimate aqueous CPs more accurately. Even so, the probable influence of chlorine atoms position on polarity and partitioning may be an argument for favoring sampling in the kinetic stage.

Emerging contaminants detected in aquaculture sites in Java, Indonesia.

Pharmaceuticals of emerging concern (acetaminophen (ACM), trimethoprim (TMP), oxytetracycline (OTC), and sulfamethoxazole (SMX)) were detected in water samples from aquaculture environments and nonaquaculture sites in four regions located on the northern coast of Central Java. ACM was the most prevalent pharmaceutical, with a mean concentration ranging from not detected (n.d.) to 5.5 ± 1.9 ngL-1 (Brebes). Among the target antibiotics (TMP, OTC, SMX), OTC was the most ubiquitous, with a mean concentration varying from n.d. to 8.0 ± 3.3 ngL-1. Correlation analysis demonstrated that there was a significant correlation between TMP and SMX concentrations. Based on ecological risk assessment evaluation, the use of OTC requires serious consideration, as it presented high health risks to algae, while ACM, TMP, and SMX posed an insignificant to moderate risk to algae, invertebrates, and fish. The findings obtained from this study highlight OTC as an emerging contaminant of prominent concern. More attention needs to be given to managing and planning for the sustainable management of shrimp farms, particularly in the northern part of Central Java.

First study of passive sampling to monitor short-chain chlorinated paraffins in water: Comparing capabilities of Chemcatcher® and silicone rubber samplers.

Short-chain chlorinated paraffins (SCCPs) are high-volume chemicals raising concerns because of their classification as priority hazardous substances by the European Water Framework Directive (WFD) and their recent inclusion in the persistent organic pollutants' (POPs) list by the Stockholm convention. As this group cover up to 5000 isomers, their measurement is still challenging. Hence the SCCPs occurrence in the environment is poorly documented in comparison with other POPs, especially in matrices where they are present at ultratrace levels such as waters. In the two-past decades, passive sampling has been increasingly used as it overcomes some major drawbacks associated to the conventional grab sampling. This study constitutes the first work aiming to examine the passive sampling's applicability for the monitoring of such complex analytes' mixtures in waters. Optimization and calibration of two proven passive samplers, namely silicone rubbers and Chemcatcher®, were performed through batch and laboratory pilot experiments. Despite the thousands of molecules present in the SCCPs mixture, the resulting global kinetic uptakes fitted well with the theorical model, for both samplers. Sampling rates of 8.0 L d-1 for silicone rubbers and 0.53 L d-1 for Chemcatcher® were found, and logKsw determined for silicone rubbers equaled 4.24 to 4.95. These values are in complete agreement with published data for other HOCs. A field trial carried out in marine coastal environments provided further evidence to demonstrate the applicability of the passive samplers to measure CPs amounts in water bodies. All these results unveil that passive sampling using silicone rubbers or Chemcatcher® can be a relevant approach to track traces of such complex mixtures in water.

Pharmaceuticals in the marine environment: What are the present challenges in their monitoring?

During the last years, there has been a growing interest in the research focused on the pharmaceutical residues in the environment. Those compounds have been recognized as a possible threat to aquatic ecosystems, due to their inherent biological activity and their "pseudo-persistence". Their presence has been relatively few investigated in the marine environment, though it is the last receiver of the continental contamination. Thus, pharmaceuticals monitoring data in marine waters are necessary to assess water quality and to allow enhancing future regulations and management decisions. A review of the current practices and challenges in monitoring strategies of pharmaceuticals in marine matrices (water, sediment and biota) is provided through the analysis of the available recent scientific literature. Key points are highlighted for the different steps of marine waters monitoring as features to consider for the targeted substance selection, the choice of the marine site configuration and sampling strategies to determine spatio-temporal trends of the contamination. Some marine environment specific features, such as the strong dilution occurring, the complex hydrodynamic and local logistical constraints are making this monitoring a very difficult and demanding task. Thus key knowledge gap priorities for future research are identified and discussed. Suitable passive samplers to monitor pharmaceutical seawater levels need further development and harmonization. Non-target analysis approaches would be promising to understand the fate of the targeted molecules and to enhance the list of substances to analyze. The implementation of integrated monitoring through long-term ecotoxicological tests on sensitive marine species at environmental levels would permit to better assess the ecological risk of these compounds for the marine ecosystems.

Ecological risk assessment of persistent organic pollutants (POPs) in surface sediments from aquaculture system.

Organochlorinated pesticides (OCPs) and Polychlorinated biphenyls (PCBs) in the surface sediments from shrimp ponds in four regions of the northern part of the Central Java coast (namely Brebes, Tegal, Pemalang, and Pekalongan) were investigated. The highest concentration of ∑ OCPs was found in Brebes Regency, ranging from 68.1 ± 3.4 to 168.1 ± 9.8 µg kg-1 dw. As indicated by the DDT ratio and chlordane ratio, the value suggested that those compounds may mainly originate from historical inputs rather than a recent application. The concentrations of Æ© 7 indicator PCBs were determined, with the concentration ranged from 1.2 ± 0.7 µg kg-1 dw (Pekalongan) to 2.2 ± 0.4 µg kg-1 dw (Tegal). The most toxic PCB congener, PCB 118, was detected in all studied regions, with the highest proportion found in Tegal. Source analysis indicated that PCBs in the sediments mainly originated from Aroclor 1254 and Aroclor 1248. Compared to sediment quality guidelines (SQGs), some OCPs were found with concentrations which potentially posed an adverse effect. Our findings suggested that more attention should be paid to ensure sustainable shrimp culture facing such a risk of the OCPs and PCBs.

Determination of Total Hydrocarbons in Contaminated Soil with "Thin Layer Sorptive Extraction Coupled with Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy".

Soil analysis using infrared spectroscopy has been proposed as an alternative to conventional soil analysis to detect soil contamination. This study therefore aims to develop an innovative, in situ, rapid, precise, and inexpensive method that is easy to implement in order to assess soil contamination with hydrocarbons. This work describes the development and validation of a new extraction method by thin-layer sorptive extraction and attenuated total reflectance-Fourier transform infrared spectroscopy (TLSE-ATR-FTIR). First, this method allows the preconcentration of thermodesorbed pollutants on a polymer thin film and then, their quantification by ATR-FTIR using a standard addition method. A five factor fractional factorial design was used to identify the most significant factors impacting the analysis. These factors include soil texture, total organic carbon (TOC), humidity, and concentrations of contaminants. The results showed that TOC, nature (clay, sandy, and loamy) of the soil, and the concentration of pollutants can affect the infrared absorbance. The analytical method has been validated by verifying the different performance criteria such as linearity, accuracy, precision, and quantitation limit. The comparison of the results obtained by TLSE-ATR-FTIR to the results of conventional analyses carried out by accredited laboratories confirms that the use of the proposed method can become an effective alternative to the current methods for the determination of the total hydrocarbons in soils.

Persistent organic pollutants in sediments of the Wouri Estuary Mangrove, Cameroon: Levels, patterns and ecotoxicological significance.

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 - 27.4, and 83 - 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

Assessment of the ecological and human health risks from metals in shrimp aquaculture environments in Central Java, Indonesia.

The occurrence and contamination level of seven important toxic metals (Cd, Cu, Co, Cr, Hg, Pb, and Zn) and three additional metals (Al, Fe, and Mn) in the water, sediment, and shrimp muscle in aquaculture areas located in Central Java, Indonesia, were investigated. The results suggest that the majority of metals have higher concentrations in the inlet followed by the outlet and ponds. Cd dissolved in the waters exhibited the highest level in Pekalongan (3.15 ± 0.33 µg L-1). Although Pb was not detected in the water, it was detected in the sediment, and the concentration ranged from 7.6 to 15.40 mg kg-1 dw. In general, the heavy metal concentrations in the sediments were found to decrease in the sequence Al > Fe > Mn > Zn > Cr > Cu > Co > Pb. Concentrations below the effects range low level based on the Canadian sediment quality guidelines were found for Cr, Cu, Pb, and Zn, whereas moderate sediment pollution (25-75 mg kg-1 dw) was observed for Cr (all regions), Cu (except in the Pekalongan region), and Zn (Brebes and Tegal regions) according to the US EPA standard. The status of the waters was evaluated by calculating a pollution index derived mostly from Mn and Zn. The ecological risk (geoaccumulation index (Igeo), contamination factor (CF), pollution load index (PLI), and potential ecological risk index (ERI)) determined in the sediments indicated that all studied areas had low to moderate contamination. The concentrations of all metals in shrimp were generally below the maximum limits for seafood, except for Zn (in all stations), Pb, and Cr (Tegal and Pekalongan). The hazard index values for metals indicated that consuming shrimp would not have adverse effects on human health.

Sorption of G-agent simulant vapours on human scalp hair.

Human scalp hair is a biological matrix that can trap chemical vapours from explosives (TNT), drugs (THC) and chemical weapons (yperite). The external contamination of human's hair following exposure to organophosphorus (OP) nerve agent was simulated by model compounds: triethyl phosphate (TEP) and diisopropyl fluorophosphate (DFP). In this work were exposed strands of hair to vapours of TEP and DFP (3 and 7 ppmv) to model sorption kinetics. Sorption isotherms were also investigated at several contamination levels (80-3000 mg min.m-3). OP nerve agent simulants were extracted from hair by soaking in DCM. Raw extracts were analysed in GC-MS/MS to quantify each simulant content in hair. Results were fitted by applying isotherm or kinetic equations. The best model was found to be bimodal first-order, suggesting the co-existence of two different mechanisms of sorption. The best equation to describe OP vapours incorporation on hair was Freundlich model. Thus hair can be used as a passive sensor able to trap chemical G-agents and can also offer valuable information regarding both individual contamination and proof of exposure to chemical weapons.

Study of organic pollution in superficial sediments of Meliane river catchment area: aliphatic and polycyclic aromatic hydrocarbons.

Organic contaminants can be accumulated in aquatic systems even at trace concentrations with potential threats to the environment and human health. The present study has been performed to evaluate the effects of organochlorines and polyaromatic hydrocarbons on surface sediments of the Meliane river catchment. Their determination provides an essential scientific approach for a better understanding of the expected sources and the processes of bioaccumulation. The concentrations of saturated hydrocarbons in extractable organic matter of the dry sediment were found ranging from 0.58 to 3 83 µg kg-1 and PAHs content ranged from 63 to 131 µg kg-1. These results indicated the adherence of Oued Meliane to the pollution of the Tunis Gulf. The fraction of saturated hydrocarbons extracted from the sediments of Oued Meliane included a majority of organic compounds of biogenic nature with a small oil input. In addition, characterization with the TAR index and the LMW/HMW index confirmed that terrigenous inputs in this fraction are more abundant than aquatic inputs. The characterization of PAHs fraction has shown its pyrolitic origin with a predominance of high molecular weight PAHs.

Structural characterization of Argania spinosa Moroccan wooden artifacts during natural degradation progress using infrared spectroscopy (ATR-FTIR) and X-Ray diffraction (XRD).

The present work is focused on spectroscopic study of four samples of Argan wooden artifact pertaining to the 17th, 18th, 20th and 21st centuries. The objective is to characterize their unknown structures by the study of their non degraded parts and to investigate changes occurred in their degraded parts due to the natural degradation process. Attenuated total reflectance Fourier transform infrared spectroscopy gauges the presence of many functional groups related to cellulose I and/or II (OH, C-O-C and -CH2), hemicelluloses (particularly C=O acetoxy ester band at 1732 cm-1), and lignin (OH phenolic, Car-O and C=Car) and provides qualitative information on the state of wood alteration by informing on the evolution of new former C=O bands. The degree of conversion to carbonyl group, especially quinone or p-quinone at 1650 cm-1, is correlated to lignin degradation, while the absence of the C=O acetoxy absorption is ascribable to occurred deterioration in hemicelluloses, and partial degradation of cellulose with enhancement of the C=O region between 1730-1630 cm-1. X-ray diffraction determines the presence of two forms of cellulose; amorphous cellulose at 18.5° 2 θ and predominant crystalline cellulose I ß at 2 θ = 22.6° which characterized by an intense peak. The decrease of crystallinity index values confirms the deterioration level and obvious changes in crystallinity level. However, the microcrystalline structure appears unaltered because no significant changes were observed for calculated cristallite seize. The obtained results depend on the prolonged time of ageing, natural deterioration phenomena, and wood part (internal or external) that is exposed to degradation. The combination of these two methods is useful for an accurate estimation of the degradation level of argan wood.

Bleaching and necrosis of staghorn coral (Acropora formosa) in laboratory assays: Immediate impact of LDPE microplastics.

The impact of low-density polyethylene (LDPE) microplastics (<100 µm; P100-A P100-B, P100-C, 100-200 µm; P200, 200-500 µm; P500) on Acropora formosa was investigated. This study investigated the bleaching and necrosis extent of A. formosa caused by LDPE contamination via laboratory assay. The staghorn coral ingested the microplastics, resulting in bleaching and necrosis that concomitantly occurred with the release of zooxanthellae. P100-A experimentation was the worst case, showing bleaching by day 2 (10.8 ±â€¯2.2%) and continued bleaching to 93.6% ±â€¯2.0 by day 14 followed by 5.9 ±â€¯2.5% necrosis. The overall results confirmed that the LDPE concentration impacts coral health. We highlighted that microplastics have been ingested and partially egested. Their presence showed either a direct or indirect impact on coral polyps via direct interaction or through photosynthesis perturbation due to microplastics that cover the coral surface.

A simple GC-MS method for the determination of diphenylamine, tolylfluanid propargite and phosalone in liver fractions.

In this study, an accurate and robust gas chromatography/mass spectrometry method was developed for quantitative analysis of diphenylamine, tolylfluanid, propargite and phosalone in liver fractions. Different injector parameters were optimized by an experimental design technique (central composite design). An optimal combination of injector temperature (°C), splitless time (min) and overpressure (kPa) values enabled to maximize the chromatographic responses. Sample preparation was based on protein precipitation using trichloroacetic acid followed by liquid-liquid extraction (LLE) of the pesticides with hexane. All compounds and endrin as internal standard were quantified without interference in selected ion monitoring mode. The calibration curves for diphenylamine, tolylfluanid, propargite and phosalone compounds were linear over the concentration range of 0.1 to 25 µM with determination coefficients (R2) higher than 0.999. A lower limit of quantification of 0.1 µM was obtained for all analytes, i.e. 422.5, 868.0, 876.2 and 919.5 µg/kg of liver fraction (hepatocytes) for diphenylamine, tolylfluanid, propargite and phosalone, respectively. All compounds showed extraction recoveries higher than 93%, with a maximum RSD of 3.4%. Intra- and inter-day accuracies varied from 88.4 to 102.9% and, imprecision varied from 1.1 to 6.7%. Stability tests demonstrated that all pesticides were stable in liver extracts during instrumental analysis (20 °C in the autosampler tray for 72 h) following three successive freeze-thaw cycles and, at -20 °C for up to 12 months. This simple and efficient analytical procedure is thus suitable for metabolism studies or for assessing mammals liver contamination.

Simultaneous grading of microplastic size sampling in the Small Islands of Bintan water, Indonesia.

Despite Indonesia being considered as second highest source of marine plastic debris in the world, few studies have been conducted on plastic debris in Indonesia, particularly microplastics. By using a simple device to simultaneously grade floating microplastics, we investigated microplastic contamination in the ecosystem of small islands in Bintan Regency, Riau Island Province, Indonesia. The average number of floating microplastics from 11 beach stations around Bintan Island was 122.8 ±â€¯67.8 pieces per station, which corresponds to 0.45 pieces per m3 and represents a low-medium microplastic pollution level compared to the levels of other marine environments worldwide. Polymer identification using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) Spectroscopy successfully identified Polyethylene (PE) (17.3 ±â€¯8.3%), Low Density PE (17.6 ±â€¯5.5%), Oxidized LDPE (<0.1%), Polypropylene (PP) (54 ±â€¯13%), PP Atactic (<0.4%), PP isotactic (<0.2%) and Polystyrene (PS) (10.4 ±â€¯9.1%) from different forms and shapes of microplastics i.e., fragments (50.9 ±â€¯4.9%), fibers (26.2 ±â€¯3%), granule (13.1 ±â€¯3.8%) and films (9.8 ±â€¯5.1%). We suggest that the generation of these microplastics was likely due to physicochemical processes, including biological degradation in this tropical ecosystem. Environmental implication of microplastics in this area increases the problems associated with ingestion, bioaccumulation and biomagnification across trophic levels and co-pollutants absorbed onto microplastics.

Desorption of sulphur mustard simulants methyl salicylate and 2-chloroethyl ethyl sulphide from contaminated scalp hair after vapour exposure.

Chemical warfare agents have been used to incapacitate, injure or kill people, in a context of war or terrorist attack. It has previously been shown that hair could trap the sulphur mustard simulants methyl salicylate and 2-chloroethyl ethyl sulphide. In order to investigate simulants persistency in hair after intense vapour exposure, their desorption kinetics were studied by using two complementary methods: hair residual content measurement and desorbed vapour monitoring. Results showed that both simulants were detected in air and could be recovered from hair 2 h after the end of exposure. Longer experiments with methyl salicylate showed that it could still be recovered from hair after 24 h. Our data were fitted with several kinetic models and best correlation was obtained with a bimodal first-order equation, suggesting a 2-step desorption kinetics model: initial fast regime followed by a slower desorption. 2-chloroethyl ethyl sulphide was also detected in the immediate environment after hair exposure for 2 h, and hair simulant content decreased by more than 80%. Our results showed that hair ability to release formerly trapped chemical toxics could lead to health hazard. Their persistency however confirmed the potentiality of hair analysis as a tool for chemical exposure assessment.

An accurate and robust LC-MS/MS method for the quantification of chlorfenvinphos, ethion and linuron in liver samples.

A method for the determination of chlorfenvinphos, ethion and linuron in liver samples by LC-MS/MS is described. Sample treatment was performed by using Sola™ polymeric reverse phase SPE cartridges after protein precipitation. Gradient elution using 10 mM ammonium formate in methanol (A) and 10 mM ammonium formate in water (B) was used for chromatographic separation of analytes on a Hypersil™ end-capped Gold PFP reverse phase column (100 mm × 2.1 mm, 3 µm). All analytes were quantified without interference, in positive ionization mode using multiple reaction monitoring (MRM) with chlorfenvinphos-d10 as internal standard. The whole procedure was validated according to the FDA guidelines for bioanalytical methods. The calibration curves for chlorfenvinphos, linuron and ethion compounds were linear over the concentration range of 0.005-2 µM (i.e. 0.0018-0.720 µg/mL, 0.0019-0.770 µg/mL and 0.0012-0.500 µg/mL respectively) with coefficients of determination higher than 0.998. A Lower limit of quantification of 0.005 µM was achieved for all analytes, i.e. 5.76, 6.08 and 3.84 µg/kg of liver for chlorfenvinphos, ethion and linuron respectively. Compounds extraction recovery rates ranged from 92.9 to 99.5% with a RSD of 2.3%. Intra- and inter-day accuracies were within 90.9 and 100%, and imprecision varied from 0.8 to 8.2%. Stability tests proved all analytes were stable in liver extracts during instrumental analysis (+12 °C in autosampler tray for 72 h) at the end of three successive freeze-thaw cycles and at -20 °C for up to 9 months. This accurate and robust analytical method is therefore suitable for contamination or metabolism studies.

Beach macro-litter monitoring and floating microplastic in a coastal area of Indonesia.

Qualitative analysis of the structures of the polymers composing floating plastic debris was performed using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and the aging of the debris was assessed by measuring carbonyl group formation on the particle surfaces. Plastic material made up >75% of the 2313 items collected during a three-year survey. The size, shape and color of the microplastic were correlated with the polymer structure. The most abundant plastic materials were polypropylene (68%) and low-density polyethylene (11%), and the predominant colors of the plastics were white, blue and green. Cilacap Bay, Indonesia, was contaminated with microplastic at a concentration of 2.5mg·m3. The carbonyl index demonstrated that most of the floating microplastic was only slightly degraded. This study highlights the need to raise environmental awareness through citizen science education and adopting good environmental practices.

Evidence of in vitro metabolic interaction effects of a chlorfenvinphos, ethion and linuron mixture on human hepatic detoxification rates.

General population exposure to pesticides mainly occurs via food and water consumption. However, their risk assessment for regulatory purposes does not currently consider the actual co-exposure to multiple substances. To address this concern, relevant experimental studies are needed to fill the lack of data concerning effects of mixture on human health. For the first time, the present work evaluated on human microsomes and liver cells the combined metabolic effects of, chlorfenvinphos, ethion and linuron, three pesticides usually found in vegetables of the European Union. Concentrations of these substances were measured during combined incubation experiments, thanks to a new analytical methodology previously developed. The collected data allowed for calculation and comparison of the intrinsic hepatic clearance of each pesticide from different combinations. Finally, the results showed clear inhibitory effects, depending on the association of the chemicals at stake. The major metabolic inhibitor observed was chlorfenvinphos. During co-incubation, it was able to decrease the intrinsic clearance of both linuron and ethion. These latter also showed a potential for metabolic inhibition mainly cytochrome P450-mediated in all cases. Here we demonstrated that human detoxification from a pesticide may be severely hampered in case of co-occurrence of other pesticides, as it is the case for drugs interactions, thus increasing the risk of adverse health effects. These results could contribute to improve the current challenging risk assessment of human and animal dietary to environmental chemical mixtures.

Levels and sources of heavy metals and PAHs in sediment of Djibouti-city (Republic of Djibouti).

Selected heavy metals and polycyclic aromatic hydrocarbons (PAHs) were determined in marine sediment from 28 sites Djibouti city. The concentrations of trace elements varied from 0 to 288.1mg/kg with relative abundance of trace metals in sediments was in the order of Zn>Cu>Ni>Cr>Co>Pb>Cd. Zn, Cu and Ni exceeded consensus based sediment quality guideline values 7, 14, 15 sites respectively. Enrichment factor and pollution load index showed relatively low to moderate contamination. The concentrations of total 16 PAHs varied widely depending on the sample location and ranged from 2.65 to 3760.11ng·g-1, with the mean concentration value of 387.87ng·g-1. Compositions and relative abundance of individual PAH using molecular diagnostic ratio using congener's m/z 178 and 202 indicated pyrolytic origin and reflecting a petroleum combustion, grass/wood and coal combustion and a petrogenic source. This study represents the first pollution baseline and a reference for future studies in Djibouti.