Congener specific analysis, spatial distribution and screening-level risk assessment of polychlorinated naphthalenes in water and sediments from two tributaries of the River Chenab, Pakistan

Porous chlorine-functionalized covalent organic framework anchored graphene aerogel composite for synergically enhanced solid phase microextraction of polychlorinated naphthalene in environmental water

The residues of polychlorinated naphthalenes (PCNs) produced in multiple industrial production and life processes are continuously entering environmental waters through atmospheric deposition and land drainage, and the water pollution caused by PCNs is continuing public concern due to their potential threat to aquatic ecosystems and public health. Herein, a new chlorine-functionalized covalent organic framework anchored graphene aerogel (COF-GA) was synthesized by covalent modification technology and used as fiber coating of solid-phase microextraction for synergically enhanced extraction of PCNs in environmental water. The extraction efficiency of COF-GA coated fiber was superior to commercial fiber due to the multiple interactions (π-π, hydrophobic interaction, and halogen bonding interaction). The COF-GA coated fiber has good stability, can avoid water vapor interference at 80 °C for a long time (30 -50 min) to maintain adsorption equilibrium, and can be reused at least 96 times. Combined with gas chromatography-tandem mass spectrometry, a sensitive method for the high-efficient enrichment (enrichment factors were 501 -7453 folds) and ultra-sensitive detection (LODs were 0.001 -0.428 pg/mL) of PCNs in environmental water was established. The enrichment factor for PCNs is significantly higher than in previous studies. This proposed method provides new technical support for the daily monitoring and risk assessment of trace PCNs in environmental water.

Distributions of PCDD/Fs, PCBs, and PCNs in coastal sediments collected from major industrial bays in South Korea

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs) were assessed in coastal sediments from industrial bays in South Korea to evaluate the pollution levels and their environmental impact. The mean sediment concentrations of Σ17 PCDD/Fs, Σ18 PCBs, and Σ15 PCNs were 198 ± 140, 3427 ± 7037, and 85 ± 336 pg/g dw, respectively. Generally, pollutant concentrations in the inner bay were higher than those in the outer bay, indicating the influence of industrial emissions and harbor activities. The primary sources were identified as steel manufacturing and wastewater treatment plants for PCDD/Fs, harbor and shipbuilding activities for PCBs, and combustion-related sources for PCNs. Notably, PCDD/F concentrations exceeded sediment guideline values. The combined effects of PCDD/Fs and PCBs demonstrated adverse impacts on aquatic organisms. Hence, the release of toxic pollutants into the marine environment could have potential biological effects due to the combined impact of these various compounds.

Spatial and temporal trends in polychlorinated naphthalenes in sediment from Ulsan and Onsan Bays of Korea: Potential sources and ecotoxicological concerns

Few studies have been conducted on spatial and temporal trends in polychlorinated naphthalenes (PCNs) in coastal environments. Here, we describe 18 PCN congeners found in surface and dated sediment samples collected from highly industrialized bays of Korea. Measurable levels of PCN congeners were detected in all sediment samples, suggesting concurrent and historical contamination. The highest PCN concentrations were observed in sediment from rivers, streams, and the inner portions of the bays, which are surrounded by industrial complexes and commercial harbors. CNs 73, 66/67, and 52 were dominant in surface and dated sediment samples. Congener patterns and diagnostic ratios revealed that PCN contamination is originated from combustion processes and the use of polychlorinated biphenyl (PCB) technical mixtures. PCN concentrations in dated sediment increased from the 1980s to the mid-2000s and then decreased to 2015. Although the toxic equivalent (TEQ) levels of PCNs in our study did not exceed sediment quality guidelines proposed by international authorities, the cumulative risks from the TEQ concentrations of polychlorinated dibenzo-p-dioxins, furans, PCBs, and PCNs can be expected for benthic organisms.

Seasonal variations and associated health risks of polychlorinated naphthalenes in Markman Canal, Eastern Cape Province, South Africa

This study focused on evaluation of the levels, seasonal variations and human health risks associated with polychlorinated naphthalenes (PCNs) in water and sediment samples of Markman Canal using solid phase and soxhlet extraction methods respectively, followed by clean-up and quantification with gas chromatograph coupled with microelectron capture detector. The sum of eight PCNs congener's (∑₈PCNs) in water and sediments varied from 0.035 to 0.699 μg/L and 0.260 to 6744.16 μg/kg dw, respectively. Highest PCNs concentrations were recorded in water during winter, while sediment samples collected during spring contained maximum levels. The estimated toxic equivalency (TEQ) for water and sediments was 1.19 × 10^-7-1.47 × 10^-4 µg/L and 4.43 × 10^-5-4.19 × 10^-1 µg/kg consecutively. The PCN levels and TEQ values revealed that this waterbody is polluted but constitutes no excess health risk. Efforts should be made to control all the activities contributing to pollution of this canal.

Partitioning and potential sources of polychlorinated naphthalenes in water-sediment system from the Yangtze River Delta, China

Spatial trends, partitioning behavior, and potential sources of polychlorinated naphthalenes (PCNs) in water-sediment system from the Yangtze River Delta (YRD) were investigated in this study. The total concentrations of 75 PCNs in water and sediment samples were 0.022-0.310 ng/L and 0.01-1.59 ng/g dry weight, respectively. The homolog patterns in the sediment and water samples were somewhat different. Di-to tetra-CNs made larger contributions in the sediment, while the mono-to tri-CNs were dominant homologs in the water. Overall, the low-chlorinated naphthalenes (mono-to tetra-CNs) were found to be the dominant homologs in the YRD water and sediment samples, and the homolog group contributions to the total PCNs concentrations decreased as the number of chlorine atoms increased. CN-5/7 and CN-24/14 were found at high concentrations in both the water and sediment. Partitioning and transfer of PCNs between water and sediment were assessed by calculating the partition coefficients and fugacity fractions. The partition coefficients showed that PCNs were not in equilibrium status in the water-sediment system, and hydrophobicity played an important role in PCNs partitioning. The fugacity fractions indicated that mono- to tri-CNs had stronger tendencies to escape from the sediment into the water, while the high-chlorinated naphthalenes close to equilibrium. Principal component analysis and correlation analysis indicated that industrial thermal processes and the use and disposal of products containing PCNs industrial products are sources of PCNs in the YRD water-sediment system.

Distributions of Polychlorinated Naphthalenes in Sediments of the Yangtze River, China

The pollution status of polychlorinated naphthalenes (PCNs) in the sediment of the Yangtze River Basin, Asia's largest river basin, was estimated. The total concentrations of PCNs (mono- to octa-CNs) ranged from 0.103 to 1.631 ng/g. Mono-, di-, and tri-PCNs-consisting of CN-1, CN-5/7, and CN-24/14, respectively, as the main congeners-were the dominant homolog groups. Combustion indicators and principal component analysis showed that the emissions from halowax mixtures were the main contributor to PCNs in sediment, among most of the sampling sites. The mean total toxic equivalent (TEQ) was calculated to be 0.045 ± 0.077 pg TEQ/g, which indicates that the PCNs in sediments were of low toxicity to aquatic organisms. This work will expand the database on the distribution and characteristics of PCNs in the river sediment of China.

Hexachloronaphthalene Induces Mitochondrial-Dependent Neurotoxicity via a Mechanism of Enhanced Production of Reactive Oxygen Species

Hexachloronaphthalene (PCN67) is one of the most toxic among polychlorinated naphthalenes. Despite the known high bioaccumulation and persistence of PCN67 in the environment, it is still unclear to what extent exposure to these substances may interfere with normal neuronal physiology and lead to neurotoxicity. Therefore, the primary goal of this study was to assess the effect of PCN67 in neuronal in vitro models. Neuronal death was assessed upon PCN67 treatment using differentiated PC12 cells and primary hippocampal neurons. At 72 h postexposure, cell viability assays showed an IC₅₀ value of 0.35 μg/ml and dose-dependent damage of neurites and concomitant downregulation of neurofilaments L and M. Moreover, we found that younger primary neurons (DIV4) were much more sensitive to PCN67 toxicity than mature cultures (DIV14). Our comprehensive analysis indicated that the application of PCN67 at the IC₅₀ concentration caused necrosis, which was reflected by an increase in LDH release, HMGB1 protein export to the cytosol, nuclear swelling, and loss of homeostatic control of energy balance. The blockage of mitochondrial calcium uniporter partially rescued the cell viability, loss of mitochondrial membrane potential (ΔΨ_m), and the overproduction of reactive oxygen species, suggesting that the underlying mechanism of neurotoxicity involved mitochondrial calcium accumulation. Increased lipid peroxidation as a consequence of oxidative stress was additionally seen for 0.1 μg/ml of PCN67, while this concentration did not affect ΔΨ_m and plasma membrane permeability. Our results show for the first time that neuronal mitochondria act as a target for PCN67 and indicate that exposure to this drug may result in neuron loss via mitochondrial-dependent mechanisms.

Occurrence and sources of PCBs, PCNs, and HCB in the atmosphere at a regional background site in east China: Implications for combustion sources

Multiple types of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), and hexachlorobenzene (HCB), can be unintentionally released from combustion or thermal industrial processes, which are speculated to be the main sources of these contaminants, as they were banned on production and use since several decades ago. In this study, concentrations and sources of 40 PCBs, 39 PCNs, and HCB were analyzed in air samples collected during the period 2012-2015 at a background site in east China. ΣPCBs, ΣPCNs, and HCB were in the range of 9-341 pg/m³, 6-143 pg/m³, and 14-522 pg/m³, respectively. Seasonal characteristics with high levels in winter and low levels in summer were observed for PCNs and HCB. PCBs also exhibited slightly higher levels in winter. Source apportionment was conducted, using polycyclic aromatic hydrocarbons (PAHs) as combustion sources indicator, combined with principal component analysis (PCA) and positive matrix factorization (PMF) model. The results indicated that the legacy of past produced and used commercial PCBs was the dominant contributor (∼56%) to the selected PCBs in the atmosphere in east China. PCNs were mainly emitted from combustion sources (∼64%), whereas HCB almost entirely originated from combustion process (>90%).

Polychlorinated Naphthalene Congener Profiles in Common Vegetation on the Tibetan Plateau as Biomonitors of Their Sources and Transportation

Polychlorinated naphthalenes (PCNs) are globally transported, carcinogenic, persistent organic pollutants (POPs) that were recently added to the Stockholm Convention with 184 parties. The Tibetan Plateau plays an important role in the global transportation and distribution of POPs. Knowledge of PCN sources and transportation on the Tibetan Plateau is important for their control globally. In this study, we quantified the congener-specific concentrations of PCNs in lichen, moss, soil, and air samples collected on the Tibetan plateau and found that common lichens were effective biomonitors for predicting atmospheric PCNs in this area. The physiochemical properties of the PCNs, the temperatures, and the lichen lipid contents were identified as important factors influencing PCN partitioning between lichens and air. Lichen-air partitioning equations were established and used to predict PCN concentrations in air in Southeast Tibet. The lichens could be used as PCN biomonitors to clarify their spatial variations, sources, and transportation in the southeast of the plateau. PCN concentrations in lichens increased with altitude, suggesting that high-mountain cold-trapping influenced the PCN transportation behavior. Principal component analysis and linear discriminant analysis showed that the major source of PCNs in this region was long-range atmospheric transportation via the Indian monsoon in summer and wind from Southwest Asia in winter. This study provides a novel method using PCN congener profiles as fingerprints and statistical models for studying the geochemical effects of conditions in high-mountain regions on the contamination behaviors of 75 congeners of the notorious PCNs.

Hexachloronaphthalene as a hemostasis disturbing factor in female Wistar rats - A pilot study

Although Persistent Organic Pollutants (POPs) are some of the most dangerous environmental toxicants, data on their impact on hemostasis are virtually limited. 1,2,3,5,6,7-hexachloronaphthalene (PCN67) seems to be one of the most toxic congeners of polychlorinated naphthalenes (PCNs), which have recently been listed as POPs. The toxic effects of PCNs are similar to other chlorinated aromatics, e.g. polychlorinated dibenzo-p-dioxins (PCDDs), so an impact on hemostasis could not be excluded. Therefore, this study examines, for the first time, if short-term (two and four weeks) exposure of a mixture of hexachloronaphthalene congeners with a PCN67 as a predominant component to female Wistar rats may have an impact on selected hemostasis parameters, such as overall potential and kinetic parameters of clot formation and fibrinolysis; hematology and basic coagulology parameters. It also examines the influence of PCN67 on the stability of erythrocyte membranes. Obtained results indicate that PCN67 may be an important disturbing factor regarding both coagulation and fibrinolysis processes, as well as platelet count. Exposure to PCN67 significantly affected clot formation and lysis processes and diminished fibrinogen concentration after both administration periods. After two weeks of administration, an increased activated partial thromboplastin time (APTT) was noted; after four weeks - decreased platelet count with concomitant increased in mean platelet volume. Moreover, PCN67 may exert adverse effects on the red blood cells membrane stability, which were manifested by a statistically significant increase of red blood cells lysis.

Measurement of PCNs in sediments collected from reservoir and river in northern Taiwan

Sediment samples were collected from a large reservoir and a river in northern Taiwan to investigate the occurrence and characteristics of Σ73PCNs analyzed. Results indicate that total concentrations of PCNs (Di- to Octa-CNs) measured in sediments collected in reservoir (29.2 ± 7.11 pg/g-dw) are significantly lower than that of samples collected in river (987 ± 440 pg/g-dw). The increasing trend of PCN concentration from upstream to downstream is found for the sediments collected in reservoir. PCN concentrations measured in surface sediments are relatively higher than that measured in sub-surface sediments collected in reservoir. Tetra-CNs consistently dominate in reservoir sediments, however, Penta-, Tetra- and Mono-CNs dominate in sediments collected at different sampling sites of the river investigated, suggesting that various sources contribute to PCNs collected from river. Indeed, diagnostic ratios indicate that mix-source contribute to PCNs measured in sediments collected from the reservoir and river in northern Taiwan.

The occurrence and distribution of polychlorinated naphthalenes (PCNs), focusing on tissue-specific bioaccumulation in crucian carp in South Korea

The occurrence and distribution of 41 congeners of polychlorinated naphthalenes (PCNs) were investigated in major tissues of crucian carp (muscle, gonad, liver, and blood) and in river sediment to assess the bioaccumulation potential of PCNs. The total PCN concentrations in sediment ranged from 4.37 to 19.5 pg/g dry weight (dw), mainly comprising CN-13, CN-33/34/37, and CN-38/40. Among fish tissues, higher PCN concentrations were observed in the gonads (29.6 ± 10.3 pg/g wet weight, ww) and liver (25.7 ± 4.35 pg/g ww) of crucian carp than in the muscle (2.17 ± 0.68 pg/g ww). CN-28/43, CN-33/34/37, CN-42, CN-52/60, CN-53/55, and CN-66/67 congeners were detected most frequently and had the highest concentration among all crucian carp tissues. We investigated the association between the PCN concentration in each tissue (muscle, liver, and gonad) and the size of the fish (total length and weight) and found positive correlations between the PCN concentration in the gonads and the total length and weight (p < 0.05, Spearman correlation).

Distribution, composition, and ecological risk of surface sedimental polychlorinated naphthalenes in the East China Sea

To reveal the pollution levels and estimate the ecological risks of polychlorinated naphthalenes (PCNs) in the East China Sea (ECS), seventy-five surface sediment samples were collected and analyzed by high-resolution mass spectrometry. PCN contents ranged from below detection limit to 261.71 ng/g dry weight (d.w.), with an integrally seaward decreasing trend. Mono-, tetra-, and hepta-CNs were the dominant homologs, and CN-2, CN-73, and CN-75 were the major individual components in most samples. CN-2 presented an obvious boundary with lower contents (16.48 ± 3.40 ng/g d.w.) in the center of the study area and higher contents (50.88 ± 10.39 ng/g d.w.) in the north and south of the boundary. The toxic equivalent (TEQ) contents ranged from 0 to 0.212 ng/g, and CN-2 and CN-73 were the predominant contributors to the TEQ.

Impacts of human activities on the spatial distribution and sources of polychlorinated naphthalenes in the middle and lower reaches of the Yellow River

The concentrations and compositions of polychlorinated naphthalenes (PCNs) in sediments and suspended particulate matters (SPM) in the middle and lower reaches of the Yellow River were investigated. The mean concentrations of PCNs were 7.15 ± 19.3 ng/g dw in the sediment and 38.1 ± 58.4 ng/g dw in SPM. Tri- and tetra-CNs were the dominant homologue groups in most samples. CN-23 was the predominant congener at all sites, and its presence may be attributed to coal combustion. Combustion indicators showed that local combustion source was the main contributor to the PCN concentrations. These sources were related to the energy structure of this region, where coal is the most important energy resource. Human activities, including industrial thermal processes and reservoir construction, were major factors affecting PCN levels and hydrological conditions, which strongly influenced the environmental fate of PCNs in the Yellow River.

Source identification, spatio-temporal distribution and ecological risk of persistent organic pollutants in sediments from the upper Danube catchment

Riverine sediments, collected on a monthly basis during a period of one year, from five sites in a mixed land use region of the Czech Republic were analysed for chlorinated and brominated persistent organic pollutants (POPs). The region is located in the upper catchment of the Danube River. The POPs concentrations were as follows: 11-930 pg g(-1) polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs), 170-980 pg g(-1) dioxin-like polychlorinated biphenyls (dl-PCBs), 34-13,700 pg g(-1) polychlorinated naphthalenes (PCNs), 5.7-29,200 pg g(-1) polybrominated diphenylethers (PBDEs) and 0.21-351 ng g(-1) hexabromocyclododecanes (HBCDs). Concentrations expressed as toxic equivalents (TEQs), for PCDD/F+dl-PCB+PCN (TEQPCDD/F+dl-PCB+PCN) ranged from 0.37 to 19 pg g(-1). The results revealed a clear spatial separation between sites based on concentration and congener profile. There were also some obvious temporal patterns of selected POPs, which were related to river flow (seasonality) and organic carbon (TOC) of the sediment. Potential sources of POPs include local municipalities (flame retardants), some diffuse sources (PCNs and PCDDs/Fs) and potential point sources (PBDEs). Risk assessment based on risk quotients (RQ) revealed limited to medium ecological risk from PBDEs. TEQPCDD/F+dl-PCB+PCN were low relative to other European rivers, hence the risk to aquatic organisms was considered to be low. PCNs contributed significantly to overall TEQ in several cases.

Human health risk assessment, congener specific analysis and spatial distribution pattern of organochlorine pesticides (OCPs) through rice crop from selected districts of Punjab Province, Pakistan

To evaluate the screening level risk assessment of OCPs in rice (Oryza sativa L.) straw (n=20) and rice grains (n=20), samples were collected from different districts of Punjab Province, Pakistan. ∑OCPs' levels (ng g(-1)) in rice straw and grains ranged from 3.63 to 39.40, 2.72 to 49.89, respectively. DDTs were found predominant over the other detected OCP isomers followed by HCH and heptachlor. Results of one way ANOVA reflected no significant difference for OCPs' levels among sampling sites, except heptachlor for rice grains. ∑OCPs' concentration in rice straw samples was exceeding the minimal residual levels (MRLs) (Australian and Japanese). Results of dietary intake and risk assessment suggested that rice straw is not safe for animals to consume as fodder. Human health was suggested to have some carcinogenic risks by consumption of rice grains, however, no considerable hazardous risk (non-carcinogenic) to human health was found.

Mycoremediation potential of Coprinus comatus in soil co-contaminated with copper and naphthalene

Experiments were conducted to investigate the effects of mycoremediation byCoprinus comatus(C. comatus) on the biochemical properties and lettuce growth in copper and naphthalene (Nap) co-contaminated soil.