Maldives: an archipelago that burns. A first survey of PCDD/Fs and DL-PCBs from human activities

Distribution and source analysis of soil toxic organic compounds of coal-electricity production base in arid and semi-arid region of China

The presence and distribution of toxic organic compounds in soil pose significant challenges. Whether their distributional characteristics are more complex, especially in arid and semi-arid regions with harsh climatic conditions? This study analyzed the composition, classification, spatial distribution, and sources of 123 toxic organic compounds in 56 soil samples of coal-electricity production base. Those compounds were classified into 11 categories, mainly pesticides (41 compounds), organic synthesis intermediates (31 compounds), and drugs (23 compounds). Seventeen of those compounds were detected over the rate of 30 %, with 13 of them being under the Toxic Substances Control Act (TSCA) inventory. The primary sources of toxic organic compounds were determined using Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF), including the degradation of pesticide residues (22.03 %), emissions of plastic pellets (16.64 %), industrial waste emissions (12.80 %), emissions from livestock (12.74 %), plastic films (11.22 %) and coal-to-liquid projects (10.78 %). This research underscores the widespread presence of toxic organic compounds in soil, highlighting their origins and distribution patterns, which are essential for developing targeted environmental management strategies in arid and semi-arid regions.

Identification of the Contamination Sources by PCBs Using Multivariate Analyses: The Case Study of the Annaba Bay (Algeria) Basin

Persistent Organic Pollutants (POPs), particularly the indicator polychlorinated biphenyls (PCBs), were first quantified in water and sediments of two wadis, Boujemaâ and Seybouse, as well as in the effluents from a fertilizer and phytosanitary production industrial plant (Fertial). Since these contaminated discharges end in Annaba Bay (Algeria) in the Mediterranean Sea, with a significant level of contamination, all the potential sources should be identified. In this work, this task is conducted by a multivariate analysis. Liquid-liquid extraction and gas chromatography/mass spectrometry (GC-MS) methods were applied to quantify seven PCB congeners, usually taken as indicators of contamination. The sum of the PCB concentrations in the sediments ranged from 1 to 6.4 μg/kg dw (dry weight) and up to 0.027 μg/L in waters. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used for the multivariate analysis, indicating that the main sources of PCB emissions in the bay are urban/domestic and agricultural/industrial. The outfalls that mostly contribute to the pollution of the gulf are the Boujemaâ wadi, followed by the Seybouse wadi, and finally by the Fertial cluster and more precisely the annex basin of the plant. Although referring to a specific site of local importance, the work aims to present a procedure and a methodological analysis that can be potentially applicable to further case studies all over the world.

PCDD/F and DL-PCB exposure among residents upwind and downwind of municipal solid waste incinerators and source identification

Understanding the environmental and human impacts associated with polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) exposure from municipal solid waste incinerators (MSWIs) is challenging because information on ambient and dietary exposure levels, spatial characteristics, and potential exposure routes is limited. In this study, 20 households from two villages located on the upwind and downwind sides of a MSWI were selected to characterize the concentration and spatial distribution of PCDD/F and DL-PCB compounds in ambient and food samples, such as dust, air, soil, chicken, egg, and rice samples. The source of exposure was identified using congener profiles and principal component analysis. Overall, the dust and rice samples had the highest and lowest mean dioxin concentrations, respectively. Significant differences were observed (p < 0.01) in PCDD/F concentrations in chicken samples and DL-PCB concentrations in rice and air samples between the upwind and downwind villages. The exposure assessment indicated that the primary risk source was dietary exposure, especially from eggs, which had a PCDD/F toxic equivalency (TEQ) range of 0.31-14.38 pg TEQ/kg body weight (bw)/day, leading to adults in one household and children in two households exceeding the World Health Organization-defined threshold of 4 pg TEQ/kg bw/day. Chicken was the main contributor to the differences between upwind and downwind exposure. Based on the established congener profiles, the exposure routes of PCDD/Fs and DL-PCBs from the environment to food to humans were clarified.

Contamination of habu (Protobothrops flavoviridis) in Okinawa, Japan by persistent organochlorine chemicals

Persistent organochlorine chemicals (OCs), including chlordane compounds (CHLs), DDTs, PCBs, and chlorinated dioxins and related compounds (DRCs), were examined in the adipose tissue and liver from 33 specimens of habu (Protobothrops flavoviridis), a species of venomous pit viper endemic to the Japanese Southwest Islands. The median concentrations of CHLs, DDTs, and PCBs in adipose tissue of 22 habus collected from an urban area were 4400 ng g^-1 lipid weight (lw), 610 ng g^-1 lw, and 1600 ng g^-1 lw, respectively. Their DDT and PCB concentrations were higher in comparison with the specimens from a rural area. Liver of 10 specimens from the urban area were subjected to DRCs analysis, and PCDDs, PCDFs, and DL-PCBs were detected with median values of 1300, 350, and 150,000 pg g^-1 lw, respectively. Among PCDD/F congeners, octa-CDD was detected at the highest concentrations in seven liver samples, but considerable concentrations of penta- and hexa-CDD/Fs were found in two samples. Relatively higher concentrations of PCB, DDTs, and PCDD/Fs were found in habus collected within 1 km of the boundary of military facilities, suggesting that OCs from some unknown sources of these OCs inside and/or around some of the facilities accumulated in habus.

Spatial distribution of microplastics around an inhabited coral island in the Maldives, Indian Ocean

Small plastic particles are considered environmental pollutants and are highly concentrated in marine sediments. However, knowledge about plastic abundance within coral reef habitat and beach sediments surrounding remote inhabited coral islands is scarce. In this study, microplastic accumulation was investigated on a small inhabited coral island located in the Maldives. Sediments from 22 sampling sites across fore reef, reef flat, and beach environments were analysed for plastic particles <5 mm. Density separation and microscope enumeration revealed a total of 1244 individual microplastic pieces, in filamentous (49%) and fragmented (51%) forms, found across all sampling sites. High concentrations were recorded at all sites, however, there was no significant relationship between microplastic concentration or size across regions (inner atoll and outer atoll) or environments (fore reef, reef flat, and beach). Furthermore, concentrations of microplastic fragment and filament forms, total concentration, and the microplastic community, showed little correlation with sediment particle size. Our findings show microplastics are ubiquitous in marine sediments around a remote coral island, at sizes ingestible by marine organisms, raising concerns about potential effects of microplastic ingestion by coral reef species.

Distribution and sources of organic contaminants in surface sediments of Hooghly river estuary and Sundarban mangrove, eastern coast of India

This study investigated polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds such as polychlorinated biphenyls (PCBs) and DDT-related pesticides in surface sediments of Hooghly estuary and the Sundarban mangrove wetlands. Concentrations of ∑₁₇PAH, ∑₁₈₂PCB and ∑₆DDT ranged from 15.4 to 1731, not detected (nd) to 13.5 and nd to 8.97 ng g^-1 dry weight, respectively. Low levels of PCBs and low to moderate concentrations of DDTs and PAHs reflected recent development in West Bengal, which was dominated by agriculture and multifarious industries in the past. Diagnostic ratios suggested that major sources of PAHs are combustion processes, DDTs are input by agriculture, antifouling paints and public health campaigns, and organochlorines are predominantly from industrial origin. Heavier PCB congeners suggest local sources and short-range transport of such chemicals. Decision makers may use these findings for managing the Hooghly River watershed in order to promote a sustainable development on the eastern coast of India.

Polycyclic and organochlorine hydrocarbons in sediments of the northern South China Sea

We investigated the concentration distribution and composition of organic pollutants in sediments of the shelf and the deep northern South China Sea (NSCS). Concentrations of polycyclic aromatic hydrocarbons (Σ₁₅PAH; 10.69-66.45 ng g^-1), Dichlorodiphenyltrichloroethane (Σ₄DDT; 0-0.82 ng g^-1), and polychlorinated biphenyls (Σ₂₄PCB; 0-0.12 ng g^-1) are below established sediment quality guidelines, suggesting no environmental risk. Surprisingly, concentrations increase from the shelf to the deep NSCS, and are higher in the east of the study area. The organic pollutant composition indicates PAH mainly derived from pyrogenic sources, and mostly degraded DDT and PCB. However, in the deep NSCS, considerable contribution of petrogenic PAH, low chlorinated PCB and p,p'-DDT suggest more recent input from different sources compared to the shelf. From these results we infer that organic pollution in the NSCS does not originate from the Pearl River Estuary but from the NE SCS, SW of Taiwan.

Microplastic and charred microplastic in the Faafu Atoll, Maldives

Microplastics are recognized as a growing threat for the marine environment that may even affect areas generally considered pristine. In this work we surveyed the microplastic contamination in the Faafu Atoll (Maldives, Indian Ocean) across twelve sampling station, located either inside or outside the reef rim. Sediments and seawater samples were collected. Despite the remoteness of the atoll, the scarce local population and low touristic annual afflux, the detected average abundance were 0.32 ± 0.15 particles/m³ in the surface water and 22.8 ± 10.5 particles/m² in the beach sediments. Polymers identified through Fourier-Transform Infrared spectroscopy were mostly polyethylene, polypropylene, polystyrene, polyvinylchloride, polyethyleneterephtalate, and polyamide. Elastomeric residues and charred microparticles were also found. In particular, the charred microparticles were prevalently located nearby the inhabited island and they might be considered a peculiarity of the area, related to local practice of burning plastic waste at the shoreline.

Concentrations of and health risks posed by polychlorinated dibenzo-p-dioxins and dibenzofurans around industrial sites in Hebei Province, China

Sintering and steel production as the main emission sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) may affect environment and human health. The concentrations, profiles, and distributions of PCDD/Fs in soil samples from around four typical sintering and steel production plants in Hebei Province, China, were determined. Forty-six soil samples were collected at distances from 500 to 9000 m from industrial plant chimneys. The concentrations of total 17 2,3,7,8-substituted PCDD/F congeners in the soil samples from sites A, B, C, and D were in the range 11-130, 13-284, 2.6-378, and 21-231 pg/g, respectively, and the internationally accepted toxic equivalent (I-TEQ) concentrations were 0.37-13.2, 0.31-12.1, 0.13-13.7, and 1.60-22.7 pg I-TEQ/g, respectively. Soil ingestion was estimated the major exposure pathway to PCDD/Fs. At current PCDD/F concentrations, the local population will be exposed to low amounts of PCDD/Fs in soil from around the industrial sites, and this exposure will pose potential health risks for the local population living at distances of less than 1000 m from nearest stack but will have no high health risks for people living further away. These results will be helpful when planning measures to control PCDD/F sources. The data will also benefit local environmental monitoring studies and be useful when assessing the risks posed by PCDD/Fs around the industrial sites to the environment and humans.

Organic pollutants in the central and coastal Beibu Gulf, South China Sea

Surface sediments from the central and coastal Beibu Gulf, southern China, were analyzed for persistent organic pollutants. The absence of polychlorinated biphenyls (PCB; generally below detection limit), low concentrations of polycyclic aromatic hydrocarbons (PAH; 24-647 ng g(-1)), and locally high contamination with organo-chloro pesticides (DDT; 0.03-92 ng g(-1)) reflect the early stages of development in southwest China, with human activities dominated by agriculture and low impact of industry. Concentrations of PCB and PAH indicate no ecological risk, while DDT accumulation poses a probable toxic risk in coastal but not in shelf sediments. Diagnostic ratios suggest PAH originating mainly from combustion of biomass and diesel fuels, and recent DDT use in agriculture and antifouling paint. Distribution patterns along the coastal-shelf-gradient indicate mainly airborne transport of PAH and waterborne transport of DDT. In the central Gulf, also water column samples reveal low concentrations of PAH (1.7-7.8 ng L(-1)) and DDT (0.006-0.053 ng L(-1)).

Temporal trends in the levels of metals, PCDD/Fs and PCBs in the vicinity of a municipal solid waste incinerator. Preliminary assessment of human health risks

The concentrations of PCDD/Fs, PCBs, and metals were determined in soil and air samples collected near a municipal solid waste incinerator (MSWI) located in Mataró (Catalonia, Spain), being the health risks for the population living in the vicinity of the facility subsequently assessed. We also established the temporal trends with respect to previous surveys performed in the same zone. In general terms, the highest environmental levels of the pollutants were found in the city of Mataró and were independent on the distance to the MSWI. Soil levels of metals did not show temporal variations between the current and previous campaigns. However, the concentrations of metals in air samples collected in 2011 and 2013, were lower than those found in our 2008 survey. Regarding PCDD/Fs and PCBs, no differences were noted between the levels of the current survey and those corresponding to 2008. Anyhow, the concentrations of metals, PCDD/Fs, and PCBs in soils and air did not exceed the reference values established by regulatory organizations, being also in the low range of other similar studies recently reported. Finally, the human non-carcinogenic and carcinogenic risks due to exposure to metals, PCDD/Fs, and PCBs, were, for the population living in the neighborhood of the MSWI, considered as acceptable according to international standards.

Two Decades of Environmental Surveillance in the Vicinity of a Waste Incinerator: Human Health Risks Associated with Metals and PCDD/Fs

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), as well as the levels of a number of heavy metals, have been periodically measured in samples of soil and vegetation collected around a municipal solid waste incinerator (MSWI) in Tarragona (Catalonia, Spain) for approximately 20 years. Since 2007, the levels of the above-mentioned pollutants have also been determined in air samples by means of either active or passive samplers. In the present study, data regarding the environmental impact of the MSWI, in terms of PCDD/Fs and heavy metals, are updated. The temporal trends of these pollutants were evaluated by comparison with data from previous surveys. In the current survey (2013-2014), mean concentrations of PCDD/Fs in soil, vegetation, and air were 0.63 ng I-TEQ/g, 0.07 ng I-TEQ/g, and 10.1 fg WHO-TEQ/m(3), respectively. Decreases of 47 and 35 % of PCDD/Fs in soil and vegetation, respectively, were observed in relation to the background study (1999). Regarding air samples, a slight temporal decrease of the PCDD/F levels was also found with the remaining concentrations staying nearly constant through time. With respect to metals, notable fluctuations in the concentrations were noted, being dependent on each specific environmental monitor. Overall, the current exposure to PCDD/Fs and metals does not mean any additional health risks for the population living near the facility. In conclusion, the results of the present study show that the environmental impact of the Tarragona MSWI is not significant, in terms of PCDD/Fs and heavy metals, after >20 years of continuous operation.