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

Scientometric trends and knowledge maps of global polychlorinated naphthalenes research over the past four decades

Polychlorinated naphthalenes (PCNs) were included in the banned list of the Stockholm Convention due to their potential to provoke a wide range of adverse effects on living organisms and the environment. Many reviews have been written to clarify the state of knowledge and identify the research needs of this pollutant class. However, studies have yet to analyse the scientometric complexities of PCN literature. In this study, we used bibliometric R and vosviewer programs as a scientometric tool to fill this gap by focusing on articles indexed on Web of Science and Scopus databases and those published between 1973 and 2022. A total of 707 articles were published within this period with a publication/author, author/publication, and co-authors/publication ratios of 0.45, 2.19, and 4.86, respectively. Developed countries dominated most scientometric indices (number of publications, citations, and collaboration networks) in the survey period. Lotka's inverse square rule of author productivity showed that Lotka's laws do not fit PCN literature. An annual percentage growth rate of 7.46% and a Kolmogorov-Smirnoff goodness-of-fit of 0.88 suggests that more output on PCNs is likely in years to come. More research is needed from scholars from developing countries to measure the supremacy of the developed nations and to effectively comply with the Stockholm Convention agreement.

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.

Health assessment of emerging persistent organic pollutants (POPs) in PM2.5 in northern and central Taiwan

Over the last two decades, Taiwan has effectively diminished atmospheric concentrations of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) through the adept utilization of advanced technologies and the implementation of air pollution control devices. Despite this success, there exists a dearth of data regarding the levels of other PM2.5-bound organic pollutants and their associated health risks. To address this gap, our study comprehensively investigates the spatial and seasonal variations, potential sources, and health risks of PCDD/Fs, Polychlorinated biphenyls (PCBs), and Polychlorinated naphthalene (PCNs) in Northern and Central Taiwan. Sampling collections were conducted at three specific locations, including six municipal waste incinerators in Northern Taiwan, as well as a traffic and an industrial site in Central Taiwan. As a result, the highest mean values of PM2.5 (20.3-39.6 μg/m3) were observed at traffic sites, followed by industrial sites (14.4-39.3 μg/m3), and the vicinity of the municipal waste incinerator (12.4-29.4 μg/m3). Additionally, PCDD/Fs and PCBs exhibited discernible seasonal fluctuations, displaying higher concentrations in winter (7.53-11.9 and 0.09-0.12 fg I-TEQWHO/m3) and spring (7.02-13.7 and 0.11-0.16 fg I-TEQWHO/m3) compared to summer and autumn. Conversely, PCNs displayed no significant seasonal variations, with peak values observed in winter (0.05-0.10 fg I-TEQWHO/m3) and spring (0.03-0.08 fg I-TEQWHO/m3). Utilizing a Positive Matrix Factorization (PMF) model, sintering plants emerged as the predominant contributors to PCDD/Fs, constituting 77.9% of emissions. Woodchip boilers (68.3%) and municipal waste incinerators (21.0%) were identified as primary contributors to PCBs, while municipal waste incinerators (64.6%) along with a secondary copper and a copper sludge smelter (22.1%) were the principal sources of PCNs. Moreover, the study specified that individuals aged 19-70 in Northern Taiwan and those under the age of 12 years in Central Taiwan were found to have a significantly higher cancer risk, with values ranging from 9.26 x 10-9-1.12 x 10-7 and from 2.50 x 10-8-2.08 x 10-7respectively.