Chapter 2 Emission, Contamination and Exposure, Fate and Transport, and National Management Strategy of Persistent Organic Pollutants in South Korea

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.

The effects of per- and polyfluoroalkyl substances on environmental and human microorganisms and their potential for bioremediation

Utilised in a variety of consumer products, per- and polyfluoroalkyl substances (PFAS) are major environmental contaminants that accumulate in living organisms due to their highly hydrophobic, lipophobic, heat-resistant, and non-biodegradable properties. This review summarizes their effects on microbial populations in soils, aquatic and biogeochemical systems, and the human microbiome. Specific microbes are insensitive to and even thrive with PFAS contamination, such as Escherichia coli and the Proteobacteria in soil and aquatic environments, while some bacterial species, such as Actinobacteria and Chloroflexi, are sensitive and drop in population. Some bacterial species, in turn, have shown success in PFAS bioremediation, such as Acidimicrobium sp. and Pseudomonas parafulva.

Nationwide assessment of atmospheric organochlorine pesticides over a decade during 2008-2017 in South Korea

Long-term nationwide atmospheric monitoring of organochlorine pesticides (OCPs) was performed in South Korea during 2008-2017. Their occurrences, seasonal and temporal variability, sources, and effect of ambient temperature were investigated. The OCPs are pronounced with a mean concentration of total OCPs ranging from 5.2 to 256 pg/Sm³. However, a decrease of 54 % was observed in the mean concentration of total OCPs from 2008 to 2017 associated with regulatory actions. OCP concentrations did not show any variations between the different site types, and OCPs were ubiquitously present at all site types. The mean concentration of total OCPs in summer was two-fold higher than in winter. The concentrations of DRINs, DDTs, ENDOs, and HCHs were significantly higher in summer, but the concentrations of chlordane and heptachlor were higher in winter. The diagnostic ratios identified major sources as ongoing sources, past use, and atmospheric transport. Clausius Clapeyron plots strongly suggested the re-emission of α-endosulfan, β-endosulfan, α-HCH, and β-HCH, and ΔH_sa (enthalpy of surface air exchange) values suggested the influence of the transport and/or new sources on aldrin, dieldrin, and chlordane. The occurrence of OCPs due to re-emissions, ongoing sources, and long-range atmospheric transport could be a challenge towards the complete phase-out of OCPs in South Korea.

Organochlorine pesticides in the urban, suburban, agricultural, and industrial soil in South Korea after three decades of ban: Spatial distribution, sources, time trend, and implicated risks

Organochlorine pesticides in soil samples across urban, suburban, agricultural, and industrial sites were analyzed every year between 2013 and 2016 in South Korea. The study aims to understand the residual status, diminution of occurrence from the South Korean environment, and its risk to humans after three decades of the ban. A general decreasing trend of OCPs has been observed over the years. The OCP concentrations were below the guideline values prescribed for soil pollution. Metabolites like p,p'-DDD and endosulfan sulfate contributed a major portion to the total OCP concentration over the years. The agricultural sites showed higher OCP levels than other site types. Compositional profile and diagnostic ratios suggested that the occurrence of DDT and endosulfan residues were due to historical inputs, but those of HCH and chlordane reflect recent usage in some pockets. The calculated incremental lifetime cancer risk was within the safety limit for all age groups across the genders in the majority of the sites. It is evident that the OCP load on soil is decreasing since the ban on usage. However, regular monitoring with a special focus on metabolites can be an effective control measure to regulate and eliminate the contamination of OCPs.

Thermal Regeneration of Spent Granular Activated Carbon Presents an Opportunity to Break the Forever PFAS Cycle

Extensive use of per- and polyfluoroalkyl substances (PFAS) has caused their ubiquitous presence in natural waters. One of the standard practices for PFAS removal from water is adsorption onto granular activated carbon (GAC); however, this approach generates a new waste stream, i.e., PFAS-laden GAC. Considering the recalcitrance of PFAS molecules in the environment, inadequate disposal (e.g., landfill or incineration) of PFAS-laden GAC may let PFAS back into the aquatic cycle. Therefore, developing approaches for PFAS-laden GAC management present unique opportunities to break its forever circulation within the aqueous environment. This comprehensive review evaluates the past two decades of research on conventional thermal regeneration of GAC and critically analyzes and summarizes the literature on regeneration of PFAS-laden GACs. Optimized thermal regeneration of PFAS-laden GACs may provide an opportunity to employ existing regeneration infrastructure to mineralize the adsorbed PFAS and recover the spent GAC. The specific objectives of this review are (i) to investigate the role of physicochemical properties of PFAS on thermal regeneration, (ii) to assess the changes in regeneration yield as well as GAC physical and chemical structure upon thermal regeneration, and (iii) to critically discuss regeneration parameters controlling the process. This literature review on the engineered regeneration process illustrates the significant promise of this approach that can break the endless environmental cycle of these forever chemicals, while preserving the desired physicochemical properties of the valuable GAC adsorbent.

Challenges and Current Status of the Biological Treatment of PFAS-Contaminated Soils

Per- and polyfluoroalkyl substances (PFAS) are Synthetic Organic Compounds (SOCs) which are of current concern as they are linked to a myriad of adverse health effects in mammals. They can be found in drinking water, rivers, groundwater, wastewater, household dust, and soils. In this review, the current challenge and status of bioremediation of PFAs in soils was examined. While several technologies to remove PFAS from soil have been developed, including adsorption, filtration, thermal treatment, chemical oxidation/reduction and soil washing, these methods are expensive, impractical for in situ treatment, use high pressures and temperatures, with most resulting in toxic waste. Biodegradation has the potential to form the basis of a cost-effective, large scale in situ remediation strategy for PFAS removal from soils. Both fungal and bacterial strains have been isolated that are capable of degrading PFAS; however, to date, information regarding the mechanisms of degradation of PFAS is limited. Through the application of new technologies in microbial ecology, such as stable isotope probing, metagenomics, transcriptomics, and metabolomics there is the potential to examine and identify the biodegradation of PFAS, a process which will underpin the development of any robust PFAS bioremediation technology.

PCDD/PCDFs and PCBs in the irrigation water in Egypt: levels, patterns, and potential sources

The contamination levels of PCDD/PCDFs in irrigation water are the most rarely studied throughout the world. The major problem in Egypt is the lack of studies and statistics about these contaminants of POPs in irrigation water. Therefore, this study is the first comprehensive report to elucidate the estimation and sources of PCDD/PCDFs and PCBs in irrigation water from Egypt and rare for worldwide may provide a reference to future studies of POPs compounds in irrigation water of Egypt. A total of 24 irrigated water samples were collected from different irrigation canals which are adjacent to industrial areas from six Egyptian governorates (Bani Swef, El-Giza, El-Sharkeya, El-Menoufeya, El-Gharbeya, and Alexandria). The study shows that irrigation water canals were contaminated with low levels of PCDDs/PCDFs, which were 0.95 pgWHO-TEQ/l, and the total of PCDD/PCDFs and dl-PCBs were 2.06 pgWHO-TEQ/l with contamination ranging between 0.88 to 2.97 pgWHO-TEQ/l while the levels of indicator PCBs were 18.52 ng/l and ranged between 0.39 to 165.6 ng/l. The most predominant dioxins congeners were HpCDD, OCDD, HpCDF, and OCDF while for dl-PCBs were PCB105 and PCB118, and for ndl-PCBs was PCB138. The areas with recent urbanization and industrialization were more contaminated with PCBs than the unindustrialized area. Lightly to moderately chlorinated congeners dominated the PCB profiles. The major sources for these contaminants were fire bricks followed by textile industries closer to the located sampling sites. The detected pattern was found to be similar to the patterns reported in the air by other studies. Although the concentrations of the studied POPs are found to be low in irrigated water, it may be considered as a potential source of soil pollution due to their accumulation process in the agricultural land and may lead to risk on human health by consuming the agricultural products irrigated by contaminated water.

Watershed-scale modeling on the fate and transport of polycyclic aromatic hydrocarbons (PAHs)

PAHs are potentially carcinogenic substances that are persistent in the environment. Increasing concentrations of PAHs were observed due to rapid urbanization, thus; monitoring PAHs concentrations is necessary. However, it is expensive to conduct intensive monitoring activities of a large number of PAHs. This study addressed this issue by developing a multimedia model coupled with a hydrological model (i.e., Soil and Water Assessment Tool (SWAT)) for Taehwa River (TR) watershed in Ulsan, the industrial capital of South Korea. The hydrologic module of the SWAT was calibrated, and further used to simulate the fate and transport of PAHs in soil and waterbody. The model demonstrated that the temporal or seasonal variation of PAHs in soil and waterbody can be well reproduced. Meanwhile, the spatial distribution of PAHs showed that urban areas in TR watershed have the highest PAH loadings compared to rural areas. Sensitivity analyses of the PAH soil and PAH water parameters were also able to determine the critical processes in TR watershed: degradation, deposition, volatilization, and wash off mechanism. We hope that this model will be able to aid the stakeholders in: regulating PAH concentrations emitted by various sources; and also apply the model to other Persistent Organic Pollutants (POPs).

Overview on relative importance of house dust ingestion in human exposure to polybrominated diphenyl ethers (PBDEs): International comparison and Korea as a case

Human exposure studies to polybrominated diphenyl ethers (PBDEs) have reached different results about the relative importance of diet intake and house dust ingestion. In the present study, concentrations of PBDEs in Korean house dust (n=15) from geographically different cities were measured, which were in agreement with a previous result, and compared with those for 22 countries of five continents collected from the most recent scientific literature. Compared with other exposure pathways, diet intake was the most important contributor to total PBDEs exposure of Korean adults (i.e., 71% of overall intake). On global comparison, total PBDE levels in house dust differed by two to three orders of magnitude among the countries investigated, with a significant relationship with gross domestic product (GDP). Whereas, dietary daily intakes exhibited a narrow difference within one order of magnitude worldwide and no relationship with GDP. Consequently, the relative importance of major two pathways depended on the contamination extent of PBDEs in house dust, which may be associated with the amount of PBDE products in use. In most countries except for UK and USA, the contribution of house dust ingestion was less important than diet intake in the current and are expected to much more mitigate in the future. However, how fast the effect of regulation will be reflected to house dust and human exposure is necessary to be monitored steadily.

Spatial distribution and source identification of indicator polychlorinated biphenyls in soil collected from the coastal multi-industrial city of Ulsan, South Korea for three consecutive years

The concentrations, profiles, and source-receptor relationships of seven indicator polychlorinated biphenyls (PCBs) (#28, 52, 101, 118, 138, 153, and 180) found in soil at 25 rural, urban, and industrial sites in Ulsan, South Korea were investigated. For this study, 75 soil samples were collected, 25 each in January of 2011, 2012, and 2013. Principal component analysis was used to evaluate the influence of the emission sources on the soil samples. The concentrations of total seven PCBs (Σ7 PCBs) ranged between 0.034 ng/g and 143 ng/g (mean: 5.10 ng/g, median: 0.440 ng/g), which indicated slight or moderate contamination levels, respectively, compared to those in the other countries or other cities in Korea. The concentrations of Σ7 PCBs at the industrial and urban sites were significantly higher than those at the rural sites, due to the direct influence of emission sources related to industrial activities rather than urban emission sources. Generally, the profiles of PCBs were dominated by penta- and hexa-chlorinated biphenyls at all the study sites, suggesting common sources of PCBs in Ulsan. PCB source identification indicated that leakage from transformer oils in the major industrial complexes and PCB-containing paints used in the automobile and shipbuilding industrial complexes were possibly the main sources of indicator PCBs in the study areas.

Occurrence of micropollutants in four major rivers in Korea

There has been an increasing concern in recent years over the presence of numerous micropollutants in river water. Simultaneously, risk assessment of micropollutants has become increasingly important due to their high toxicity. Therefore, the aims of this study were to characterize the levels of micropollutants in rivers, to identify the sources of these pollutants, and to evaluate their risk quotients (RQ) to the ecological system. Monitoring data from 159 sites distributed across four major rivers in Korea were collected from the Ministry of the Environment (KME) reports. Tests were performed to check for the presence of 35 pollutants in river waters, from which 29 pollutants were detected. Organochlorine pesticides (OCPs) occurred most frequently, at low concentrations, whereas volatile organic compounds (VOCs) and phthalates were detected at higher concentrations. Based on this study, it was suggested that the factories near the sampling sites where pollutants were found represent one of the main sources of chemicals. After comparing the industrial activities with the measured pollutants, although the released amounts were not reported, representative intermediate chemicals were found in the river water. The RQs of most VOCs were below one, despite their concentration range being higher, compared with other pollutants. Methyl bromide and di-n-octyl phthalate occurred frequently in the Han River Basin and the Nakdong River Basin, respectively, and their RQs were consistently high, so further studies should focus on their exact emission source in order to reduce ecological risk. The results suggest that it will be necessary to develop methods of risk assessment that are more tailored to the various micropollutants present in river water, in addition to the implementation of water treatment systems to reduce ecological risk.

Assessment of trace pollutants in Korean coastal sediments using the triad approach: a review

Here we summarize and review the previous efforts on sediment assessment together with major scientific findings that were conducted in the Korean coastal waters since late 1990s. Towards integrated triad analysis, sediment data (>1700 samples) reported from the Korean coasts were collected and reviewed of which data collectively includes three components of chemical, toxicological, and ecological measures. First, the chemistry data suggested widespread and historic distribution of sedimentary pollutants along the Korean coasts. Spatial distributions suggested that their sources were independent of each other, while some localized areas (highlighted for Lake Shihwa, Masan Bay, and Ulsan Bay) and zones with extremely high pressures of certain pollutants were also identified. The mass balance analyses and/or direct correlations linking triad components reflected a general agreement between endpoints. The benthic community responses given by species occurrence and diversity also reflected the type and degree of sediment contamination, however, could not be fully explained by the known target chemicals. Overall, the triad assessment of trace pollutants in Korean coastal sediments seemed to be useful and much powerful when all the components are fully addressed.

Biomagnification of persistent chlorinated and brominated contaminants in food web components of the Yellow Sea

Concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) were measured in 32 species inhabiting the Yellow Sea to assess their bioaccumulation potentials. The concentrations in these samples were lower than those reported for other countries or locations. Relatively high levels of BDE 209 in biota suggest an ongoing source of deca-BDE technical mixing within the Yellow Sea. The accumulation profiles of PCBs were uniform between species, but the concentrations of OCPs and PBDEs varied widely. Pelagic and benthic food-chain components were separated by their δ(13)C values. Significant positive correlations between δ(15)N and PCB 153, PCB 138, p,p'-DDE, oxy-chlordane, and trans-nonachlordane were found only for pelagic consumers, indicating that the pelagic food chain is an important bioaccumulation pathway for selected PCB and OCP compounds. The other compounds did not show any biomagnification through benthic and pelagic food chains, suggesting the lower bioaccumulation potentials of these contaminants.

Polybrominated diphenyl ethers and synthetic musks in umbilical cord serum, maternal serum, and breast milk from Seoul, South Korea

Fetal and maternal exposure levels of two emerging pollutants, polybrominated diephenyl ethers (PBDEs) and synthetic musks, were measured in Korean general population to assess prenatal and postnatal exposures in infants. For this purpose, paired samples of breast milk, maternal and cord blood were collected from 20 Korean women in 2007. In comparison to data from other countries and previous data from Korea, relatively higher and gradually increasing concentrations for PBDEs were found in Korean breast milk (< LOQ to 590 ng g(-1) lipid wt; median=90 ng g(-1)). Differences in PBDEs and musk concentrations were found among age groups and parity levels. PBDEs concentrations in breast milk were lower in the younger mothers and/or the mothers with multiple parities, while these trends were not found for musks. Compared with PBDEs, concentrations of musks were significantly lower in breast milk than in serum and a little correlation in concentrations among the three human biological matrices were observed. The differences in the profiles of musks relative to PBDEs were due to different clearance rates between these two compounds. The average hazard quotients (HQs) for daily intake of PBDEs by infants via lactation were 0.62, 0.42, and 0.19 for BDE-47, BDE-99, and BDE-153, respectively.

Distribution of organochlorine pesticides in intertidal and subtidal sediments in coastal wetland with high tidal ranges

The present study aimed to understand the distribution characteristics of organochlorine pesticides (OCPs) in wetlands experiencing high tides and the manner in which these characteristics are affected by various factors, in particular, two distinct physical and topographical features (i.e., sub- and intertidal zones). For all OCPs except HCHs, the distribution levels were higher in the intertidal zone than in the subtidal zone. The spatial heterogeneity in the isomer compositional pattern, distribution levels, and correlation among individual OCPs were pronounced in the intertidal zone. Spatial homogeneity was observed within the subtidal zone, indicating that the effect of flushing and mixing was strong enough to diminish the potential local concentration peaks and unique composition pattern. It was evident that input paths and their strength impact the horizontal and transversal distribution of OCPs. The OCP group-specific discrepancy in spatial distribution suggested that (1) chlordane and chlorobenzenes were from a single dominant innermost terrestrial input path, (2) DDTs were from multiple terrestrial input paths, and (3) HCH was likely to be from the outer sea. The observations in this study imply that (1) benthic organisms could experience greater exposure in the intertidal basin than in the subtidal zone and (2) management measures of OCPs should be set after considering the tidal effect and the OCP-specific input paths.