Multiple evaluation of the potential toxic effects of sediments and biota collected from an oil-polluted area around Abu Ali Island, Saudi Arabia, Arabian Gulf.

After the Gulf War Oil Spill, there have been many investigations about distributions of oil-derived pollutants nearby areas, but lacking in ecotoxicological assessment. We evaluated the potential toxicity of asphalt mats, sediments, and biota (polychaetes, chitons, snapping shrimps, and crabs) by combining two bioassays (H4IIE-luc and Vibrio fischeri) and in situ microbial community (eDNA). Samples were collected from Abu Ali Island, and organic extracts were bioassayed and further fractionated according to the chemical polarity using silica gel column. Great aryl hydrocarbon receptor (AhR)-mediated potencies and inhibition of bioluminescence were mainly found in aromatics (F2) and saturates (F1) fractions of asphalt mat and sediments, respectively, while great toxicological responses in biota samples were found in resins and polar (F3) fraction. We also confirmed that potential toxicities of biota were species-specific; great AhR-mediated potencies were found in polychaetes and great bioluminescence inhibitions were found in crabs. In microbial communities, most genera (up to 90%) were associated with polycyclic aromatic hydrocarbons (PAHs)-degrading bacteria, supporting that PAHs are the primary stressors of the benthic community around Abu Ali Island. The present study provides useful information on the contamination status, risk assessment of environmental matrices and benthic organisms in Abu Ali Island.

Bioaccumulation of Polycyclic Aromatic Hydrocarbons (PAHs) by the Marine Clam, Mactra veneriformis, Chronically Exposed to Oil-Suspended Particulate Matter Aggregates.

Dispersion and biodegradation of petroleum hydrocarbons are significantly enhanced by formation of oil-suspended particulate matter aggregates (OSAs), but little is known about their adverse effects on benthic invertebrates or microbes. In this study, we investigated: (1) bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) by the marine bivalve, Mactra veneriformis and (2) changes in composition and relative abundances of microbes, during 50-d of an OSAs feeding experiment. Total concentrations of PAHs increased more rapidly during the first week of exposure, peaked at Day 30, then gradually declined to the end of experiment. While bioaccumulation of PAHs by clams varied among the 20 target compounds, two major groups of PAHs were identified by cluster analysis. One group including 3-methylphenanthrene, 1,6-dimethylphenanthrene, 1,2,6,9-tetramethylphenanthrene, and benzo[ a]anthracene showed a fairly constant rate of accumulation, while the second group including 2-methyldibenzothiophene, 2,4-dimethyldibenzothiophene, 2,4,7-trimethyldibenzothiophene, 3-methylchrysene, 6-ethylchrysene, and 1,3,6-trimethylchrysene exhibited a bell-shaped pattern. Bioaccumulation of PAHs by clams was dependent on changes in abundance of Gammaproteobacteria, indicating active degradations of hydrocarbons by selected species. Six key species included: Porticoccus litoralis, Porticoccus hydrocarbonoclasticus, Cycloclasticus spirillensus, Alcanivorax borkumensis, Alcanivorax dieselolei, and Alkalimarinus sediminis. These results are the first to demonstrate interactions of OSAs and macrofauna/microbe in oil cleanup operations.

Phytoplankton assemblage responses to massive freshwater inputs and anthropogenic toxic substances contamination in the Geum River Estuary, South Korea.

This study investigated the relationships between phytoplankton assemblages and water contamination by persistent toxic substances (PTSs) and nutrients in an estuary with an artificial dam over one year. The distribution of PTSs, including 15 polycyclic aromatic hydrocarbons, 6 alkylphenols, and 8 metal(loid)s, along with nutrients, exhibited relatively high concentrations with irregular temporal fluctuations in the inner estuary. During winter and spring, phytoplankton communities showed good ecological quality, with an average of 28 species and a density of 1750 cells L-1. In contrast, during summer, there was a significant increase in the density of freshwater species (max 45,000 cells L-1). These assemblages were categorized into three seasonal groups, featuring dominant taxa like blue-green algae and diatoms. Temperature and nutrient levels were the principal factors influencing phytoplankton assemblages, while PTSs had a minor impact. Overall, phytoplankton assemblages displayed strong seasonal variation, mainly influenced by freshwater input and nutrient availability.

Historical trends of traditional, emerging, and halogenated polycyclic aromatic hydrocarbons recorded in core sediments from the coastal areas of the Yellow and Bohai seas.

Historical trends of polycyclic aromatic hydrocarbons (PAHs) contamination were reconstructed from eleven sediment cores located in intertidal zones of the Yellow and Bohai seas for a period encompassing the last 80 years. The analysis encompassed 15 traditional PAHs (t-PAHs), 9 emerging PAHs (e-PAHs), and 30 halogenated PAHs (Hl-PAHs), including 10 chlorinated PAHs (Cl-PAHs) and 20 brominated PAHs (Br-PAHs). Concentrations of target PAHs were highest in industrial and municipal areas situated along the coast of the Bohai Sea, including Huludao, Yingkou, Tianjin, and Dandong, constituting a substantial mass inventory. All target PAHs showed increasing trends since the 1950s, reflecting the development history of South Korea and China. High molecular weight PAHs accumulated in sampling sites more than low molecular weight PAHs. A positive matrix factorization model showed that the PAH sources were coal and gasoline combustion (35%), diesel combustion (33%), and biomass combustion (32%). Over the last 80 years, the contribution of coal and gasoline combustion increased in all regions, while diesel combustion and biomass combustion varied across regions and over time. Toxicity equivalence values were highest for t-PAHs (>99% contribution), followed by Cl-PAHs, Br-PAHs, and e-PAHs. Concentrations of t-PAHs in Eastern Asia seas have increased since the 1900s, particularly in intertidal areas compared to subtidal areas. The intertidal zone removed 83% of the total flux of PAHs originating from land and thus appears to serve as a buffer zone against marine pollution. Overall, this study provides novel knowledge on the historical trends and sources of PAHs on a large scale, along with insights for future coastal management.

Instrumental and bioanalytical characterization of dioxin-like activity in sediments from the Yeongsan River and the Nakdong River estuaries, South Korea.

In the present study, we investigated the contamination status of dioxin-like chemicals (DLCs) and potential toxic effects associated with river and coastal sediments from two large estuaries of South Korea. Sediments collected from the Yeongsan River and the Nakdong River estuaries were analyzed for several DLCs, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), coplanar polychlorinated biphenyls (co-PCBs), and polycyclic aromatic hydrocarbons (PAHs). Greater concentrations of target DLCs (except for PCDDs in Nakdong River) were found in the inland creeks with decreasing trends towards estuarine and coastal areas in both regions. The result indicated that the elevated DLCs were attributable to the surrounding land use activities, such as point sources of industrial and municipal areas from the inland regions. Principal component analysis and positive matrix factorization model revealed that major sources of PCDD/Fs and PAHs in sediments were fly ash and dust, and petroleum and diesel emission, respectively. The dioxin-like activities of the sediments ranged from 0.98 to 88% of the maximal induction elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin, which generally explained the sedimentary contamination by the target DLCs. Dioxin-like activity in sediments from the artificial lake and inland creek of the Nakdong River Estuary was mostly explained by the targeted DLCs (~75%). However, the contribution of known DLCs from the sediments of the Yeongsan River Estuary was relatively low (~35%) compared to that of the Nakdong River Estuary, suggesting the presence of unknown DLCs in sediments. Overall, the distribution of DLCs quite varied by region, generally reflecting the difference in the surrounding land use activity. In the future, it is needed to study the distribution, sources, and potential ecological effects of unknown toxic substances in coastal sediments.

Distributions and potential sources of traditional and emerging polycyclic aromatic hydrocarbons in sediments from the lower reach of the Yangtze River, China.

This study investigated the current contamination status and potential sources of traditional and emerging polycyclic aromatic hydrocarbons (t-PAHs and e-PAHs) in the sediments across a wide area of the Yangtze River, spanning nine cities. Fifty-seven sediment samples were collected in 2019, from which 15 t-PAHs and 11 e-PAHs were analyzed using GC-MSD. In addition, organic carbon (OC), total nitrogen (TN), and carbon and nitrogen stable isotope ratios (δ13C and δ15N) in sediments were measured to evaluate associations with PAHs contamination. OC, TN, and their stable isotope ratios showed a wide range of site-specific contents and values, indicating high variation in contamination and sources. Concentrations of t-PAHs and e-PAHs in sediments ranged from 0.6 to 200,000 ng g-1 dry weight (dw) and 1.1 to 20,000 ng g-1 dw, respectively. Hotspot sites located in Nanjing (PuKou), Taizhou (JingJiang), and Suzhou (ZhangJiaGang). PAHs contamination reflected land use type and human activity in the surrounding area. Positive matrix factorization (PMF) modeling showed that, on average (n = 57), vehicle emissions were the most dominant contribution (57%), followed by petroleum (28%) and fossil fuel combustion (15%). Sites with high PAHs contamination in sediments were of severe ecological risk. Contributions to the potential risks of PAHs were most significant in the order of dibenz[a,h]anthracene, benzo[b]fluoranthene, and benzo[a]pyrene. The primary origin of these compounds appeared to be fossil fuel combustion. The results of this study are expected to provide useful baseline data on the current contamination status and potential sources of traditional and emerging pollutants in the sediments of the Yangtze River, China.

10 years long-term assessment on characterizing spatiotemporal trend and source apportionment of metal(loid)s in terrestrial soils along the west coast of South Korea.

Long-term trends in the spatial distributions and sources of metal(loid)s in soils adjacent to the west coastal areas of South Korea have been systematically investigated for 10 years (2010-2019). Monitoring in 17 sites clearly showed site- and region-specific distributions, being associated with land use type (significant differences, as road > agriculture > wild) (P < 0.05), rather than temporal variation. The great concentrations of all metal(loid)s were found near Lake Shihwa (LS) and Geum River (GG), near the road, indicating that transportation activity was the main source of metal(loid)s contamination in soil. Especially, Cd (0.5 mg kg-1), Hg (0.04 mg kg-1), Pb (65 mg kg-1), and Zn (184 mg kg-1), related to the transportation activity near the road, showed twice greater than other land use types, on average. The concentration of metal(loid)s in each site and with the same land use type did not greatly vary over the years, with no significant annual difference (P > 0.05). The degree of metal(loid)s contamination compared to the background levels was identified in the order of Pb > Zn > Cr > Cu > As>Cd > Ni > Hg, with the contaminated hotspots mostly in LS or GG. The potential ecological risk was evidenced for Cd and Hg, but such a trend was temporally irregular over the years, indicating site-specificity. The sources of metal(loid)s were carefully determined as natural (20%), fuel combustion & agricultural pollution (43%), and vehicular emissions (37%) using the Positive Matrix Factorization model. The relative contribution of each source to contamination over the last decade was found to be similar, supporting that site-dependent lesser variation in metal(loid)s contamination in the coastal areas of South Korea. Overall, the distribution of metal(loid)s in the soil near the west coastal areas over the last decade largely depended on land use activities, and contamination degree was associated with non-point sources, such as transportation and fuel combustion.

Spatiotemporal variation and sources of soil heavy metals along the lower reaches of Yangtze River, China.

Excessive accumulation of soil heavy metals (HMs) result in the deterioration of soil quality and reduction of agricultural productivity and safety. The accumulation status, temporal change, and sources of soil HMs were determined by large-scale field surveys in 2014 and 2019 in rapid urbanization and industrialization area along the lower reaches of the Yangtze River, China. Eighty-two surface soil samples were collected in 2014 and ninety-five surface soil samples and seven soil profiles (0-100 cm) were collected in 2019. The mean concentrations (in, mg kg-1) of As (10.17), Cd (0.33), Cr (86.38), Cu (38.22), Hg (0.11), Ni (37.67), Pb (43.95), and Zn (113.15) were greater than the corresponding background values. The concentrations of these 8 HMs significantly varied with site-specific distributions depending on nearby landscape patterns with decreasing order: agricultural soil around industrial > agricultural soil > fallow soil. Cd and Hg were found to be priority pollutants due to their greater accumulations in this study area. Combined analyses of principal component analysis and positive matrix factorization model addressed source apportionment of soil HMs. Industrial activities, parent materials, and agricultural and traffic activities were three major sources and their contributions were 35.56%, 35.20%, and 29.23%, respectively. The concentrations of soil As, Cd, Cr and Pb increased with time. This study elucidates how changes in land uses and time affect soil HMs and provides reasonable suggestions for the effective reduction of HM contamination in economically and industrially developed areas of China, and elsewhere.

Evaluation of ecotoxicological effects associated with coastal sediments of the Yellow Sea large marine ecosystem using the marine copepod Tigriopus japonicus.

A copepod bioassay with Tigriopus japonicus was applied to evaluate the relative ecotoxicity of sediments in the Yellow and Bohai seas, and contributions of individual PAHs to copepod toxicity were evaluated. Mean toxicity was greatest in the Yellow Sea of China, followed by the Bohai Sea and Yellow Sea of Korea. Elevated concentrations of sedimentary PAHs, alkylphenols, and styrene oligomers back-supported the significant toxicities observed in bioassay. Copepod toxicity in relation to PAHs indicated the greatest contribution by indeno[1,2,3-c,d]pyrene. However, lacked contribution by PAHs, viz., 2.4 and 3.0 % for the total immobilization and mortality, respectively, indicated a large proportion of unknown toxicants being widely distributed along the Yellow Sea Large Marine Ecosystem (YSLME) coastline. Overall, the present study provides useful baseline information for evaluating the potential sedimentary toxicants, with emphasizing further investigation to identify the unknown toxicants at an LME scale, and elsewhere.

Spatial distribution and source identification of traditional and emerging persistent toxic substances in the offshore sediment of South Korea.

While the coastal pollution of persistent toxic substances (PTSs) has been widely documented, information on offshore environments remains limited. Here, we investigated the spatial distribution and sources of PTSs in the offshore sediments (n = 34) of South Korea. Sediment samples collected from the Yellow Sea (n = 18), the South Sea (n = 10), and the East Sea (n = 6), in 2017-18 were analyzed for a total of 71 PTSs. Target compounds include 31 PCBs, 15 PAHs, 9 emerging PAHs (e-PAHs), 10 styrene oligomers (SOs), and 6 alkylphenols (APs). Sedimentary PCBs showed relatively low concentrations with no significant difference across the three seas (0.16-6.9 ng g-1 normalized organic carbon, OC). Low-chlorinated PCBs (tri- and tetra Cl-CBs) were predominant (mean: 77%), primarily indicating atmospheric inputs. PAHs widely accumulated in the three seas with low to moderate level (22-250 ng g-1 OC), and dominated by high molecular weight PAHs (4-6 rings). PMF analysis revealed coast-specific PAHs sources; i.e., originated from mainly coke production (77%) in the Yellow Sea, vehicle emissions (68%) in the South Sea, and fossil fuel combustion (49%) in the East Sea. SOs showed significant contamination than other PTSs, with elevated concentrations in the Yellow Sea (mean: 350 ng g-1 OC). APs showed a similar regional distribution to SOs, but concentrations were much lower (mean: 17 ng g-1 OC). SOs and APs seemed to be introduced from rivers and estuaries on the west coast of Korea, where industrial and municipal activities are concentrated, then might be transported to offshore through tide or currents. Overall, the novel data presented for various PTSs in offshore Korean sediments warrant the necessity of a long-term monitoring effort and urgent management practice to protect marine ecosystem.

Macrozoobenthic community responses to sedimentary contaminations by anthropogenic toxic substances in the Geum River Estuary, South Korea.

We investigated the sedimentary pollution by persistent toxic substances (PTSs) and their potential impacts on the macrobenthic faunal community in the Geum River Estuary, South Korea. Sediment and benthic macrofauna samples were collected from eight sites every two months during the period of February to December in 2015. Target PTSs encompassed metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn), one metalloid (As), polycyclic aromatic hydrocarbons (PAHs), and alkylphenols (APs). The significant difference to the environment of the inner and outer parts of the estuary (p < 0.05) was found with relatively high concentrations of PTSs in sediment from the inner estuary. The concentrations of Cu and Zn exceeded the sediment quality guidelines of Korea representing a potential risk to aquatic organisms. The primary source of PAHs was by-products of diesel and gasoline combustion (37%), followed by a coke oven (32%) and oil-burning (31%). The macrofaunal community was spatially distinguished between the inner and outer parts of the estuary (p < 0.05), regardless of the season. In the inner part of the estuary, the density of the macrofaunal community was high, due to the increased opportunistic species and/or some indicator species (organic polluted or enrichment), implying that the given environment was disturbed. Among the environmental parameters analyzed by the distance-based linear model (DistLM), salinity, chlorophyll-a, and nutrient concentrations were found to be key factors controlling the changes in macrofaunal community structure. Such changes in the closed estuary system would indicate that each taxonomic group had to adjust to lower salinities and alternative food sources. Overall, the distribution of PTSs and macrozoobenthic communities in the Geum River Estuary collectively reflected the environmental gradients caused by surrounding activities in the inner part of the estuary together with direct effects by the irregular inflow of freshwater.

Perfluoroalkyl acids in rapidly developing coastal areas of China and South Korea: Spatiotemporal variation and source apportionment.

Polyfluoroalkyl substances (PFASs) are recognized as emerging contaminants that have captured worldwide attention. They are primarily transported in environments and spread around the globe due to their persistent and bioaccumulative characteristics. In this study, 15 PFASs were detected in major rivers of the rapidly developing coastal areas of China and South Korea. The concentrations and compositions of these PFASs varied greatly between different regions along the coastline. The total concentrations ranged from 14.9 to 16,500 ng L-1, and the mean concentrations of Σ15PFASs in Liaodong Bay, Bohai Bay, Laizhou Bay, and the west coast of South Korea were 124 ng L-1, 81.4 ng L-1, 1550 ng L-1, and 36.2 ng L-1, respectively. In Laizhou Bay, the relatively high perfluorooctanoic acid (PFOA) was due to the high usage and manufacturing of PFOA-containing products and contributed 59% of the total compounds. In Liaodong Bay and Bohai Bay, PFBA and PFOA were the most abundant compounds, accounting for >55% of the total compounds. Along the west coast of South Korea, PFBA and PFPeA were the most prevalent compounds, contributing 28% and 24% of the total compounds, respectively. The data collected in the last decade were analyzed to investigate the temporal trends of selected PFASs. The total concentration of Σ10 PFASs decreased in both China and South Korea, while the proportion of short-chain PFASs increased. The proportion of C4-C7 PFCAs in South Korea rapidly increased from 46% to 79% but decreased from 49% to 43% in China. The positive matrix factorization (PMF) model successfully addressed the site-specific source apportionment, which showed that 53% of the PFASs in Laizhou Bay were due to fluorine manufacturing. The results of this study provide novel insights into elucidating the spatiotemporal distribution and complicated sources of PFASs over a large area and provide a clear message for all stakeholders, water and coastal managers, and scientists.

Occurrence, distribution and affecting factors of microplastics in agricultural soils along the lower reaches of Yangtze River, China.

Microplastics become one of the serious persistent pollutants in terrestrial environments, and thus may represent a threat to the quality of soil and inhabiting organisms. It is imperative to understand occurrence and distribution of microplastics in soils. In this study, a large-scale field survey encompassing 85 locations along the lower reaches of Yangtze River and estuary was performed to investigate the microplastics abundance in agricultural soils. Microplastics were isolated from all the samples and all depths (0-80 cm). The microplastics abundance in soils ranged from 4.94 items/kg to 252.70 items/kg, with an average of 37.32 items/kg. The most common microplastic type detected was Polypropylene (PP) occurring as white fragments with sizes ranging from 0.1 mm to 0.5 mm. Abiotic parameters such as soil pH and texture were the general factors being associated with microplastic abundance. Meantime, traffic was indicated as one important factor to affect the microplastic abundance. Overall, the road input seems to be the main source of microplastic pollution in agricultural areas along the Yangtze River and estuary. Further studies should elucidate the original of the plastic fragments in order to establish a baseline for regulative initiatives securing environmental protection.

Large-scale sediment toxicity assessment over the 15,000 km of coastline in the Yellow and Bohai seas, East Asia.

The Yellow and Bohai seas have long been contaminated by persistent toxic substances (PTSs) from numerous (un)known anthropogenic sources. In this study, we used Vibrio fischeri bioassay to evaluate ecotoxicological profiles associated with sedimentary PTSs contamination at a large marine ecosystem (LME) scale. A total of 125 surface sediments collected from the coastal areas of the Yellow and Bohai seas were analyzed both for aqueous and organic extracts. Not surprisingly, the results indicated site-dependent toxicities, but most sites were identified as non-toxic to V. fischeri. For aqueous extracts and organic extracts, 13% and 8% of samples, respectively exhibited marginal toxicity, while 0% and 2% of samples exhibited moderate toxicity. However, it should be noted that organic extracts (mean TU = 56) induced stronger toxicities than aqueous samples (mean TU = 0.4). This result generally back-supported the high toxicity potentials associated with sedimentary sink of organic pollutants. Several PTSs measured in the samples indicated a significant contribution to the observed V. fischeri toxicities. Of note, polycyclic aromatic hydrocarbons (PAHs; r = 0.28, p < 0.05), styrene oligomers (r = 0.41, p < 0.01), and alkylphenols (r = 0.38, p < 0.05) showed significant associations to the observed bacterial inhibition. Among PAHs, benzo[a]anthracene and phenanthrene exhibited a significant contribution to the observed V. fischeri toxicities. Meantime, salinity which reflects the distance from the point sources of land-driven pollutants along the rivers and estuaries in the Yellow and Bohai seas was a key environmental variable representing the sample toxicities. Overall, the present study provides baseline information for evaluating the potential sediment toxicity to implement responsible coastal management at an LME scale, and elsewhere.

Current contamination status of traditional and emerging persistent toxic substances in the sediments of Ulsan Bay, South Korea.

Contamination status of traditional and emerging persistent toxic substances (PTSs) in sediments and their major sources were investigated in Ulsan Bay, Korea. A total of 47 PTSs, including 15 traditional PAHs, ten styrene oligomers (SOs), six alkylphenols (APs), and 16 emerging PAHs (E-PAHs) were analyzed. Concentrations of traditional PAHs, SOs, and APs ranged from 35 to 1300 ng g-1 dry weight (dw), 30 to 3800 ng g-1 dw, and 30 to 430 ng g-1 dw, respectively. For the last 20 years, PTSs contamination in the bay area has been improved. However, 12 E-PAHs were widely detected in sediments, with a maximum of 240 ng g-1 dw (for benzo[e]pyrene) at the creek site. These E-PAHs seemed to originate from surrounding activities, such as biomass combustion, mobile sources, and diesel combustion. Due to environmental concerns for E-PAHs, further research on the potential toxicity, distribution, and behavior of these compounds should be implemented.

Large-scale monitoring and ecological risk assessment of persistent toxic substances in riverine, estuarine, and coastal sediments of the Yellow and Bohai seas.

The Yellow and Bohai seas comprise one of the most rapidly developing regions in the world, but efforts to assess coastal pollution by persistent toxic substances (PTSs) on wide spatial scale are lacking. The present study aimed to (1) measure the concentrations of PTSs, such as polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and styrene oligomers (SOs) via large-scale sediment monitoring (total of 125 locations), (2) assess potential ecological risk of PTSs in sediments to coastal ecosystems, (3) estimate various sources and fresh inputs of PTSs, (4) determine distribution patterns of PTSs by human activities and land-use type, and (5) address decadal (2008-2018) changes in distributions of PTSs. The high concentrations of PAHs [> 7000 ng g-1 dry weight (dw)] in sediments were detected in Nantong in the Yellow Sea of China (YSC) and Huludao and Qinhuangdao in the Bohai Sea (BS), whereas lesser concentrations (< 200 ng g-1 dw) were detected in the Yellow Sea of Korea (YSK). We found relatively high concentrations of sedimentary APs and SOs in Nantong, Huludao, and Qinhuangdao from the YSC and BS regions, but corresponding concentrations were generally below < 100 ng g-1 dw in other locations. Concentrations of PAHs at 38 locations (30% of YSC and BS) posed a potential risk to aquatic ecosystems, whereas relatively low risk concentrations occurred in all locations of YSK. The main source of PAHs (concentrated in YSC and BS) were by-products of diesel and gasoline combustion (42% of total concentration), whereas biomass combustion (24%) dominated in YSK. Fresh inputs of PTSs indicated that the generation and use of PTSs continue across all regions and locations. Among PTSs, concentrations of PAHs were significantly associated with location (p < 0.05) relative to land-use within a given region, whereas concentrations of APs and SOs showed no significant relationships (p > 0.05) among or within regions. Over time, concentrations of PAHs have generally declined, but sediment contamination has increased at some locations in China, with sources shifting from a mixture of PAHs types to those linked to diesel and gasoline combustion. Additional studies are needed on the fate and potential ecological risk posed by certain PTSs in hotspots. This is one of the first efforts providing backgrounds on PTS pollution in the large marine ecosystem of the Yellow and Bohai seas.

Anthropogenic impacts on the contamination of pharmaceuticals and personal care products (PPCPs) in the coastal environments of the Yellow and Bohai seas.

Pharmaceuticals and personal care products (PPCPs) are recognized as one emerging group of environmental contaminants, capturing worldwide attention. These chemicals, closely connected to anthropogenic activities, are mainly transported through aquatic environments and reach coastal areas, eventually entering ocean offshore. Thus, this study concentrated on the 30 PPCPs in coastal waters of the Yellow and Bohai seas (77 sites), a fast-growing area with intensive anthropogenic activities. In general, the total concentrations of PPCPs in Chinese coastal waters (0.880-1194 ng L-1) greatly varied and were relatively greater than those (9.91-442 ng L-1) in Korean coastal waters. Sulfamethoxazole, sulfamethazine, oxytetracycline, ofloxacin, roxithromycin, anhydro-erythromycin, and caffeine were the seven predominant PPCPs in the coastal waters of study area. Further, we established the Predicted PPCPs Contamination Indicator (PPCI) to address potential anthropogenic activities being associated with site-specific PPCPs contamination. Three anthropogenic factors to PPCPs contamination were proven as the most influential, including (1) quantity of wastewater discharge, (2) gross product of meat, poultry, eggs and milk, and (3) gross aquatic product. The relatively high PPCI values appeared in Tianjin, Dalian, Tangshan, Yantai, and Qingdao in China and Gyeonggi and Jeonbuk in South Korea, which exhibited fairly good consistency with the corresponding PPCPs concentrations. A mini-review of the global PPCPs distributions revealed that seven priority PPCPs found in this study distributed widely in Asia rather than Europe, North America, and Australia. In general, global PPCPs contamination also reflected site- and region-specific distributions, suggesting varying usages and sources cross the region and/or country. Finally, the risk assessment suggested that ofloxacin and anhydro-erythromycin, with 36.4% and 23.4% sites higher than medium risks respectively, posed relatively high risks to sensitive algal species, Microcystis aeruginosa and Selenastrum capricornutum. Overall, the ecological risks of exposure of PPCPs in the Yellow and Bohai seas were higher compared to other regions of the world, thus the bilateral management of PPCPs between China and South Korea needs an immediate attention.

Long-term trends of persistent toxic substances and potential toxicities in sediments along the west coast of South Korea.

For decades, in response to industrialization and urbanization, environmental qualities of estuarine and coastal areas of the west coast of Korea have been deteriorating. Long-term changes in concentrations of persistent toxic substances (PTSs) in sediments, including PAHs, styrene oligomers, nonylphenols, and metals and their potential toxicities via AhR- and ER-mediated potencies, and bioluminescent bacterial inhibition, were investigated. Long-term monitoring in five estuarine and coastal areas (2010-2018; 10 sites) showed that concentrations of PAHs and nonylphenols in sediments have declined while concentrations of some metals, Cd, Cr, and Hg have increased. Similarly, AhR-mediated potencies in sediments have declined, but inhibitions of bioluminescent bacteria have increased. Concentrations of sedimentary PAHs and AhR-mediated potencies were significantly (p < 0.01) and positively correlated. Sources of PAHs from combustion have been gradually declining while inputs from vehicle exhaust by-products have been increasing. Overall, this study brought our attention a balanced regulation in chemical-specific manner.

Major AhR-active chemicals in sediments of Lake Sihwa, South Korea: Application of effect-directed analysis combined with full-scan screening analysis.

This study utilized effect-directed analysis (EDA) combined with full-scan screening analysis (FSA) to identify aryl hydrocarbon receptor (AhR)-active compounds in sediments of inland creeks flowing into Lake Sihwa, South Korea. The specific objectives were to (i) investigate the major AhR-active fractions of organic extracts of sediments by using H4IIE-luc in vitro bioassay (4 h and 72 h exposures), (ii) quantify known AhR agonists, such as polycyclic aromatic hydrocarbons (PAHs) and styrene oligomers (SOs), (iii) identify unknown AhR agonists by use of gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOFMS), and (iv) determine contributions of AhR agonists to total potencies measured by use of the bioassay. FSA was conducted on fractions F2.6 and F2.7 (aromatics with log Kow 5-7) in extracts of sediment from Siheung Creek (industrial area). Those fractions exhibited significant AhR-mediated potency as well as relatively great concentrations of PAHs and SOs. FSA detected 461 and 449 compounds in F2.6 and F2.7, respectively. Of these, five tentative candidates of AhR agonist were selected based on NIST library matching, aromatic structures and numbers of rings, and available standards. Benz[b]anthracene, 11H-benzo[a]fluorene, and 4,5-methanochrysene exhibited significant AhR-mediated potency in the H4IIE-luc bioassay, and relative potencies of these compounds were determined. Potency balance analysis demonstrated that these three newly identified AhR agonists explained 1.1% to 67% of total induced AhR-mediated potencies of samples, which were particularly great for industrial sediments. Follow-up studies on sources and ecotoxicological effects of these compounds in coastal environments would be required.

Anthropogenic influences on benthic food web dynamics by interrupted freshwater discharge in a closed Geum River estuary, Korea.

Stable isotope analysis was used to investigate the benthic food web dynamics in the Geum River estuary where continuous river flow has been blocked by a sea dike over the past 25 years. In order to address the dike effect(s) on distribution of food sources (i.e., organic matters and microphytobenthos) and their utilization by marine predators, a three years monitoring survey (total of 30 surveys) was seasonally conducted at four fixed locations at both inside of dike and outer tidal flats. All the collected biota (total of 19 species; >1100 individuals and microphytobenthos) and abiotic (n = 118) samples were analyzed for carbon (δ13C) and nitrogen (δ15N) stable isotopes. In particular, two dominant marine bivalves inhabiting outer reach of tidal flats, Mactra veneriformis and Cyclina sinensis, were targeted to identify their feeding strategies that being related to a year-round population growth. In general, the stable isotopic signatures of samples indicated dissimilarity in distribution of organic matters between inside and outside of dike, supporting geographical and/or trophic isolation. The taxa-dependent trophic levels are also evidenced in consistent manner, with two to three levels being positioned over the years. Meantime, their dietary contributions varied in time, i.e., seasonal chances in compositions of major food sources (microphytobenthos and particulate organic matters) were observed for two target bivalves. Such temporal variations could be further linked to selective feedings that evidenced by age(size)-dependent and/or tissue specific distributions. Altogether, the present study suggested seasonality, diet preference, and growth dependent food web dynamics in the Geum River estuary. Overall, the present study suggested that the stable isotopic technique could be a powerful tool for characterizing the long-term anthropogenic influences of a sea dike on marine food-web dynamics.