Soil concentrations, compositional profiles, sources and bioavailability of polychlorinated dibenzo dioxins/furans, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in open municipal dumpsites of Chennai city, India

Spatial distributions and source identification of PCDD/Fs and PCBs in soils and pine needles in the multi-industrial city of Ulsan, South Korea

The spatial distribution and contamination patterns of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in soil and pine needles from the multi-industrial city of Ulsan, South Korea were assessed. The mean concentrations of Σ17 PCDD/Fs, Σ12 dl-PCBs, and Σ7 I-PCBs were 78 pg/g dw, 90 pg/g dw, and 453 pg/g dw in the soil and 6 pg/g ww, 31 pg/g ww, and 166 pg/g ww in the pine needles, respectively. The mean concentrations of PCDD/Fs, dl-PCBs, and I-PCBs in the soil at industrial sites (138, 184, and 453 pg/g dw) were significantly higher than those at urban (47, 33, and 186 pg/g dw) and suburban sites (48, 49, and 234 pg/g dw). In the pine needles, although PCDD/F and PCB levels were higher at several industrial sites, mean concentrations at the industrial (6, 31, and 166 pg/g ww), urban (4, 29, and 143 pg/g ww), and suburban (4, 31, and 169 pg/g ww) sites were comparable, indicating that atmospheric transport plays a crucial role in spreading contamination throughout the study area. Higher chlorinated PCBs were predominant in the soils, while PCDFs and lower chlorinated PCBs were more common in the pine needles, reflecting the distinct physicochemical properties and interactions of these chemicals with each medium. Principal Component Analysis (PCA) revealed industrial combustion as the main source of PCDD/Fs and PCBs, with Aroclors identified as an additional source of PCBs. Suburban areas were influenced by both local sources and pollutants transported from urban and industrial areas. This study highlights that industrial activities and atmospheric transport significantly contribute to the widespread contamination of PCDD/Fs and PCBs in Ulsan.

A review of advanced bioremediation technologies for dioxin-contaminated soil treatment: Current and future outlook

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF), namely known as dioxins, are persistent organic compounds with high toxicity. The presence of dioxins in soil is a major environmental issue worldwide, as it negatively impacts both ecosystems and human health. Thus, several advanced techniques have been applied to overcome this issue, offering promising treatment efficiency and cost-effectiveness. This review employs a meta-analysis strategy to provide an up-to-date assessment of the global situation of dioxin-contaminated soil. Dioxin concentrations are commonly higher in industrial and urban areas than in rural areas, primarily due to anthropogenic activities such as chemical manufacturing and waste incineration. Furthermore, several advanced bioremediation technologies for dioxin treatment, including biosurfactants, composting, and phytoremediation were highlighted and thoroughly discussed. Aerobic composting has proven to be robust in removing dioxins, achieving treatment efficiencies ranging from 65% to 85%. Whereas, phytoremediation, particularly when involving agricultural crops like zucchini, cucumber, and wheat, shows great promise in dioxin removal through various mechanisms, including root uptake and transpiration. Notably, biosurfactants such as rhamnolipids and sophorolipids have been effectively used to remediate dioxin-contaminated soil due to their significantly enhanced bioavailability of dioxins and their interaction with microbes. This review provides a comprehensive understanding of advanced biotechnologies for remediating dioxin-contaminated soil. It also addresses the technical and economic aspects of dioxin treatment and identifies future directions and research perspectives to fill knowledge gaps in this field.

Resource recovery from legacy waste dumpsites in India: A path towards sustainable waste management

Legacy waste dumpsites have been a significant environmental concern in India for many years. These dumpsites are characterized by the uncontrolled disposal of Municipal Solid Waste (MSW) and have led to various types of pollution and disease outbreaks. As India faces the challenges of rapid urbanization and increased waste generation and with over 3000 legacy waste dumpsites in the country, the need to address these legacy waste dumpsites has become paramount. As we continue to struggle extensively for waste management as well as space, landfill mining has been recognized as a promising way of recovering resources in our country by employing various technological and engineering advancements to extract valuable materials and energy from legacy waste streams. Unlike existing waste management approaches, this review explores the application of a novel Recovery Potential Index (RPI) for legacy waste dumpsites in India, which evaluates the feasibility of waste treatment facilities based on waste compositions and recovered material quantities. Depending on the RPI, recovered fine fractions can be sold as city compost or used as fill material, while recyclable, combustible, and inert fractions could be directed towards appropriate recycling or landfill uses. Unscientific and uncontrolled landfill mining practices could lead to unanticipated impacts on the nearby environment in the form of heavy contamination, thereby presenting this practice as a challenge in addition to the immense opportunities it provides.

A commercial humic acid inhibits benzo(a)pyrene biodegradation by Paracoccus aminovorans HPD-2

Benzo(a)pyrene (BaP) is posing serious threats to soil ecosystems and its bioremediation usually limited by environmental factors and microbial activity. Humic acid (HA), a ubiquitous heterogeneous organic matter, which could affect the fate of environmental pollutants. However, the impact of HA on bioremediation of organic contamination remains controversial. In the present study, the biodegradation of BaP by Paracoccus aminovorans HPD-2 with and without HA was explored. Approximately 87.4 % of BaP was biodegraded in the HPD-2 treatment after 5 days of incubation, whereas the addition of HA dramatically reduced BaP biodegradation to 56.0 %. The limited BaP biodegradation in the HA + HPD-2 treatment was probably due to the decrease of BaP bioavailability which induced by the adsorption of HA with unspecific interactions. The excitation-emission matrix (EEM) of fluorescence characteristics showed that strain HPD-2 was responsible for the presence of protein-like substances and the microbial original humic substances in the HPD-2 treatment. Addition of HA would result in the increase of soluble microbial humic-like material, which should ascribe to the biodegradation of BaP and probably utilization of HA. Furthermore, both the growth and survival of strain HPD-2 were inhibited in the HA + HPD-2 treatment, because of the limited available carbon source (i.e. BaP) at the presence of HA. The expression of gene1789 and gene2589 dramatically decreased in the HA + HPD-2 treatment, and this should be responsible for the decrease of BaP biodegradation as well. This study reveals the mechanism that HA affect the BaP biodegradation, and the decrease of biodegradation should ascribe to the interaction of HA and bacterial strain. Thus, the bioremediation strategies of PAHs need to consider the effects of organic matter in environment.

Exposure estimation and neurotoxicity inhibition of dioxins in sensitive populations near domestic waste incineration plant through adverse outcome pathway

The neurotoxicity induced by dioxins has been recognized as a serious concern to sensitive population living near waste incineration plants. However, investigating the intracellular neurotoxicity of dioxin in humans and the corresponding mitigation strategies has been barely studied. Thus, a domestic waste incineration plant was selected in this study to characterize the neurotoxicity risks of sensitive populations by estimating the ratio of dioxin in human cells using membrane structure dynamics simulation; and constructing a complete dioxin neurotoxicity adverse outcome pathway considering the binding process of AhR/ARNT dimer protein and dioxin response element (DRE). Six dioxins with high neurotoxicity risk were identified. According to the composite neurotoxicity risk analysis, the highest composite neurotoxicity risk appeared when the six dioxins were jointly exposed. Dietary schemes were designed using 1/2 partial factor experimental design to mitigate the composite neurotoxicity risk of six dioxins and No. 16 was screened as the optimum combination which can effectively alleviate the composite neurotoxicity risk by 29.52%. Mechanism analysis shows that the interaction between AhR/ARNT dimer protein and DRE was inhibited under the optimal dietary scheme. This study provides theoretical feasibility and reference significance for assessing composite toxicity risks of pollutants and safety mitigation measures for toxic effects.

Polychlorinated biphenyls in bovine milk from a typical informal electronic waste recycling and related source regions in southern India before and after the COVID-19 pandemic outbreak

For more than a decade, Chennai city in southern India has been evidenced with informal electronic waste (e-waste) recycling and open burning practices as the potential sources for polychlorinated biphenyls (PCBs). PCBs can bioaccumulate in livestock particularly cows grazing on the contaminated soil. The outbreak of the COVID-19 pandemic led to additional challenges associated with waste management practices. Hence this study aims to elucidate twenty-five PCB congeners in bovine milk from the previously reported PCB source regions in Chennai and the suburbs before and after about three years of the pandemic outbreak along electronic waste recycling (EWR), open burning dumps (OBD), and residential (RES) transects. The geomean concentration of Ʃ25PCBs in ng/g lipid weight (lw) followed a decreasing trend of EWR (13 ng/g lw) > OBD (8 ng/g lw) > RES (4 ng/g lw). Over 80 % of PCBs stemmed from EWR and OBD transects before and after the pandemic. However, a significant surge in the level of PCB-52 was observed in the OBD transect after the pandemic outbreak. Most toxic PCB congeners, PCB-126 and -169 were significant contributors to TEQs in EWR and OBD transects and can be reasoned with the burning of waste materials and mixed plastics in these transects. The highest average daily dose (ADD) exposure risk was for children from EWR and was significantly higher (p < 0.05) than other transects. Mean ADD-induced TEQ (6.6 pg TEQ/kg-bw/day) from the cows grazing around Kodungaiyur dumpsite slightly exceeded the EU guideline of 5.5 pg TEQ/kg-bw/day after the outbreak of the pandemic due to PCB-126. However, none of the samples exceeded the US FDA (1.5μg/g milk fat) recommendation limits for PCBs in milk fat. Prolonged exposure to such persistent organic pollutants interlinked with the burning of mixed waste in the open dumps can be a public health concern.

Interlinkage Between Persistent Organic Pollutants and Plastic in the Waste Management System of India: An Overview

Improper handling of plastic waste and related chemical pollution has garnered much attention in recent years owing to the associated detrimental impacts on human health and the environment. This article reports an overview of the main interlinkages between persistent organic pollutants (POPs) and plastic in the waste management system of India. Both plastics and POPs share certain common traits such as persistence, resistance to biological degradation, and the ability to get transported over long distances. Throughout the processes of production, consumption, and disposal, plastics interact with and accumulate POPs through several mechanisms and end up co-existing in the environment. Plastic waste can undergo long-range transport through rivers and the oceans, break down into microplastics and get transported through the air, or remain locked in waste dump yards and landfills. Over time, environmental processes lead to the leaching and release of accumulated POPs from these plastic wastes. Plastic recycling in the Indian informal sector including smelting, scrubbing, and shredding of plastic waste, is also a potential major POPs source that demands further investigation. The presence of POPs in plastic waste and their fate in the plastic recycling process have not yet been elucidated. By enhancing our understanding of these processes, this paper may aid policy decisions to combat the release of POPs from different waste types and processes in India.

Heterologous spatial distribution of soil polycyclic aromatic hydrocarbons and the primary influencing factors in three industrial parks

Soil polycyclic aromatic hydrocarbons (PAHs) generated from industrial processes are highly spatially heterologous, with limited quantitative studies on their main influencing factors. The present study evaluated the soil PAHs in three types of industrial parks (a petrochemical industrial park, a brominated flame retardant manufacturing park, and an e-waste dismantling park) and their surroundings. The total concentrations of 16 PAHs in the parks were 340-2.43 × 10³, 26.2-2.63 × 10³, and 394-2.01 × 10⁴ ng/g, which were significantly higher than those in the surrounding areas by 1-2 orders of magnitude, respectively. The highest soil PAH contamination was observed in the e-waste dismantling park. Nap can be considered as characteristic pollutant in the petrochemical industrial park, while Phe in the flame retardant manufacturing park and e-waste dismantling park. Low molecular weight PAHs (2-3 rings) predominated in the petrochemical industrial park (73.0%) and the surrounding area of brominated flame retardant manufacturing park (80.3%). However, high molecular weight PAHs (4-6 rings) were enriched in the other sampling sites, indicating distinct sources and determinants of soil PAHs. Source apportionment results suggested that PAHs in the parks were mainly derived from the leakage of petroleum products in the petroleum manufacturing process and pyrolysis or combustion of fossil fuels. Contrarily, the PAHs in the surrounding areas could have been derived from the historical coal combustion and traffic emissions. Source emissions, wind direction, and local topography influenced the PAH spatial distributions.

Concentration, source apportionment and potential carcinogenic risks of polycyclic aromatic hydrocarbons (PAHs) in roadside soils

PAHs are organic pollutants that have carcinogenic and mutagenic impacts on human health and are a subject of great concern. The soil-bound polycyclic aromatic hydrocarbons (PAHs) in the urban areas can be very lethal to human health. The concentrations, sources, and possible cancer risks of 15 PAHs were analysed by collecting roadside soil samples in Lucknow, India. The range of ∑₁₅PAHs was found to be 478.94 ng/g to 8164.07 ng/g with a mean concentration of 3748.23 ng/g. The highest contribution (32.5%) was found to be from four-ring PAHs, followed by six-ring (24.5%) and five-ring (16.7%) PAHs. The source apportionment through diagnostic ratios ANT/(ANT + PHE) against FL-2/(FL-2+PYR) highlighted the dominance of petroleum, wood, coal, and grass combustion as sources of PAHs in the study area. Source apportionment was also done through positive matrix factorization, confirming the dominance of 'vehicular emissions' (49%), followed by 'coal and biomass combustion' (∼39%), and 'leakages, volatilization and petroleum combustion' (∼12%) as potential sources. The results from lifetime cancer risks (ILCR) varied in the range of 7.5 × 10^-4 and 1.3 × 10 × ^-2 illustrating 'high cancer risk'. The total cancer risk susceptibility of children was found to be 31% more than that of adults. The highest risk associated with toxic equivalent concentration (TEQ) was found at site S8 highlighting the impact of the presence of an international airport, and huge traffic load. The present study will prove to be useful for information related to human exposure to PAHs content in soil in the study area and as baseline study for policy makers, stakeholders, and researchers.