Integrated assessment of the natural purification capacity of tidal flat for persistent toxic substances and heavy metals in contaminated sediments.

Natural purification of pollutants is highly recognized as regulating ecosystem services; however, the purification capacity of tidal flats remains largely unknown and/or unquantified. A 60-day mesocosm transplant experiment was conducted in situ to assess the purification capacity of natural tidal flats. We adopted the advanced sediment quality triad approach, monitoring 10 endpoints, including chemical reduction, toxicity changes, and community recoveries. The results indicated that contaminated sediments rapidly recovered over time, particularly > 50% within a day, then slowly recovered up to âˆ¼ 70% in a given period (60 days). A significant early reduction of parent pollutants was evidenced across all treatments, primarily due to active bacterial decomposition. Notably, the presence of benthic fauna and vegetated halophytes in the treatments significantly enhanced the purification of pollutants in both efficacy and efficiency. A forecast linear modeling further suggested additive effects of biota on the natural purification of tidal flats, reducing a full recovery time from 500 to 300 days. Overall, the triad approach with machine learning practices successfully demonstrated quantitative insight into the integrated assessment of natural purification.

Best available technique for the recovery of marine benthic communities in a gravel shore after the oil spill: A mesocosm-based sediment triad assessment.

Ecotoxicological effects of spilled oils are well documented, but study of recovery of marine benthic communities is limited. Long-term recovery of hard bottom communities during physical and biological remediations after a spill was monitored. A 60-day experiment was conducted using a mesocosm with monitoring of eight endpoints by use of the sediment quality triad (SQT). First, physical treatment of hot water + high pressure flushing maximally removed residual oils (max=93%), showing the greatest recovery among SQT variables (mean=72%). Physical cleanup generally involved adverse effects such as depression of the microphytobenthic community during the initial period. Next, biological treatments, such as fertilizer, emulsifier, enzyme and augmentation of the microbes, all facilitated removal of oil (max=66%) enhancing ecological recovery. Analysis of the microbiome confirmed that oil-degrading bacteria, such as Dietzia sp. and Rosevarius sp. were present. A mixed bioremediation, including fertilizer + multi-enzyme + microbes (FMeM) maximized efficacy of remediation as indicated by SQT parameters (mean=47%). Natural attenuation with "no treatment" showed comparable recovery to other remediations. Considering economic availability, environmental performance, and technical applicability, of currently available techniques, combined treatments of physical removal via hand wiping followed by FMeM could be most effective for recovery of the rocky shore benthic community.

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.

Blue economy and the total environment: Mapping the interface.

The term 'Blue Economy (BE)' is increasingly popular in modern environmental research. The concept seeks to explore ocean-based development opportunities with environmental stewardship and protection. Yet different scholars and actors adopt this term often in conflicting ways without attempting to explore the relevance and the link between the blue economy and the broader environment viz., total environment. The potential opportunities to resolve the conflicts require a better understanding of the impacts and/or interactions of the BE on the total environment. This paper aims to map the interface between the two for a better understanding of the total environment and implications for the BE. Using a systematic literature review, this study finds that the field of the blue economy in association with the total environment is very new and emerging in the literature, and the link between the BE and the total environment is increasingly being invoked, yet clarity on the link or interactions remain vague. By analysing the co-occurrence of selected keywords and networks, we present six clusters (three for general relationship, and the other three for specific dimensions of total environment). In a general relationship between the BE and the total environment, clusters of environmental sustainability, marine resource, and economic development are identified to link directly to the BE. In specific dimensions of the total environment, clusters of growth and sustainable development, spatial planning and environmental management, and environmental sustainability and the BE are presented. The analysis outcomes show that specific areas from the total environment (growth, spatial planning, environmental management, and environmental sustainability) are directly linked to the BE where a call for a wider range of studies in the future is identified.

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.

DNA-based diversity assessment reveals a new coral barnacle, Cantellius alveoporae sp. nov. (Balanomorpha: Pyrgomatidae) exclusively associated with the high latitude coral Alveopora japonica in the waters of southern Korea.

In the present study, the Indo-Pacific coral associated barnacle Cantellius euspinulosum (Broch, 1931) was found to have cryptic species in Korea, Taiwan and other regions based on molecular studies. However, the original specimens of C. euspinulosum from Broch have not been previously described or illustrated, making it difficult to assign which cryptic species to the original C. euspinulosum. The original specimen of C. euspinulosum was examined and illustrated here, and the species identity of C. cf. euspinulosum collected from Jejudo Island in the present study and other cryptic species (based on literature illustrations) in the Indo-Pacific were evaluated.C. euspinulosum from Singapore, Java, Mergui Archipelago in Andaman Sea and Nha Trang represented the C. euspinulosum identified by Broch (1931). It is a generalist on Acropora, Favia, Favites, Leptoria, Montipora, Pachyseris and Pocillipora corals and distributed in the Indo-Pacific region. Morphological examination and DNA sequencing (COI, 12S DNA sequences) in the present study showed that C. cf. euspinulosum from Jejudo Island, Korea represents a distinct species, herein named C. alveoporae sp. nov. Cantellius alveroporae sp. nov. is a specialist species that only grows on Alveopora and also present in Palau, and Ogasawara Island in Japan. Cantellius cf. euspinuloum in Taiwan, the Moscos Island, and Australia belong to several other distinct species awaiting further morphological and molecular studies. At least five cryptic species of C. euspinulosum were identified in the present study, including both specialist and generalists.

Characteristics of long-term changes in microbial communities from contaminated sediments along the west coast of South Korea: Ecological assessment with eDNA and physicochemical analyses.

The environmental DNA (eDNA) metabarcoding was applied to assess benthic ecological health in the west coast of South Korea by investigating a long-term microbial community change (2015-17). The ecological interaction among microorganisms, from phylum to family level, and their associations to environmental variables across the five regions were highlighted. As part of the study, the available chemistry and toxicological data in the regions during the monitoring periods were incorporated into an integrated sediment triad assessment. The bacterial communities were dominated by Proteobacteria (34.2%), Bacteroidetes (13.8%), and Firmicutes (10.8%). Proteobacteria and Bacteroidetes dominated consistently across regions and years, while Firmicutes and Cyanobacteria significantly varied by region and years (p < 0.05). The abundance of this phylum declined over time with the increasing abundance of Cyanobacteria, indicating their independent interactions to certain environmental changes. Planctomycetes and Gemmatimonadetes linked to some contaminants (ΣPAHs and Cu), implying indicator taxa. Overall, eDNA-based microbial community analysis combined with exposures of contaminants and responses of microorganisms is a promising strategy for the assessment of benthic ecological health in contaminated sediments from coastal waters.

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.

Integrated assessment of west coast of South Korea by use of benthic bacterial community structure as determined by eDNA, concentrations of contaminants, and in vitro bioassays.

During the past few decades, contamination of sediments by persistent toxic substances (PTSs) has been observed in estuarine and coastal areas on the west coast of South Korea. The contaminants are suspected to cause toxicities in aquatic biota, but little is known about their ecological effects, particularly on benthic microbial communities. In this study, an eDNA-based assessment was applied along with classic assessments of exposure, such as chemistry and in vitro bioassays, to evaluate condition of benthic bacterial communities subjected to PTSs. Two strategies were adopted for the study. One was to conduct a comprehensive assessment in space (by comparing seawater and freshwater sites at five coastal regions) and in time (by following change over a 5-y period). Although we found that bacterial composition varied among and within years, some phyla, such as Proteobacteria (28.7%), Actinobacteria (13.1%), Firmicutes (12.7%), and Chloroflexi (12.5%) were consistently dominated across the study regions. Certain bacterial groups, such as Firmicutes and Verrucomicrobia have been linked to contamination at some sites in the study area and at specific points in time. Bacterial communities were not significantly correlated with salinity or AhR- and ER-mediated potencies, whereas concentrations of PAHs, APs, and certain metals (Cd and Hg) exhibited significant associations to the structure of bacterial communities at the phylum level. In fact, the relative abundance of microbes in the phylum Planctomycetes was significantly and negatively correlated with concentrations of PAHs and metals. Thus, the relative abundance of Planctomycetes could be used as an indicator of sedimentary contamination by PAHs and/or metals. Based on our correlation analyses, Cd and ER-mediated potencies were associated more with bacterial abundances at the class taxonomic level than were other PTSs and metals. Overall, the eDNA-based assessment was useful by augmenting more traditional measures of exposure and responses in a sediment triad approach and has potential as a more rapid screening tool.

The Blue Economy and the United Nations' sustainable development goals: Challenges and opportunities.

The "Blue Economy (BE)" is an increasingly popular concept as a strategy for safeguarding the world's oceans and water resources. It may emerge when economic activity is in balance with the long term capacity of ocean ecosystems to support the activity in a sustainable manner. Importantly, the concept of BE posits the inherent conflicts between two discourses-growth and development, and protection of ocean resources. The inherent conflicts require solutions to embrace the opportunities associated with the ocean economy while recognizing and addressing its threats. The potential solutions on a global scale are advocated by the United Nations in their Sustainable Development Goals (SDGs). However, we notice that the identification of the scope and boundaries of the BE in line with the UN's SDGs is vague even challenging, and the key stakeholders and their interests and roles in the BE are also vague. This review examines the scientific evidence of the association between the BE and the UN's SDGs, and relevance and alignment of stakeholders on the link between the BE and SDGs. Based on a literature survey between 1998 and 2018, we find that BE is highly associated with SDGs 14-17. Notably, we find that stakeholders prefer SDG 3 Good Health & Well-Being and SDG 8 Decent Work & Economic Growth in the BE context. As stakeholder involvement shows some differences and variations in the relationship between the BE and SDGs, we consider that stakeholders can play some roles directly or indirectly in the BE-SDGs context. In order to set achievable goals and targets in BE-SDGs, we support that key stakeholders should be identified to play several important roles in prosperous economic, societal development and setting tolerable ranges for the ocean biosphere.

Integrated assessment of persistent toxic substances in sediments from Masan Bay, South Korea: Comparison between 1998 and 2014.

Complexity of anthropogenic influences on coastal ecosystems necessitates use of an integrated assessment strategy for effective interpretation and subsequent management. In this study a multiple lines of evidence (LOE) approach for sediment assessment, that combined use of chemistry, toxicity, and benthic community structure in the sediment quality triad was used to assess spatiotemporal changes and potential risks of persistent toxic substances (PTSs) in sediments of Masan Bay highlighting "long-term changes" between 1998 and 2014. Specific target objectives encompassed sedimentary PTSs (PAHs, alkylphenols (APs), and styrene oligomers), potential aryl hydrocarbon receptor (AhR; H4IIE-luc assay)- and estrogen receptor (ER; MVLN assay)-mediated activities, and finally several ecological quality (EcoQ) indices of benthic community structure. Concentrations of target PTSs in Masan Bay sediments were generally less by half in 2014 compared to those measured in 1998. Second, AhR-mediated potencies in sediments also decreased during this time interval, whereas ER-mediated potencies increased (+3790%), indicating that there has been substantial ongoing, input of ER agonists over the past 16 years. Potency balance analysis revealed that only 3% and 22% of the AhR- and ER-mediated potencies could be explained by identified known chemicals, such as PAHs and APs, respectively. This result indicated that non-targeted AhR and ER agonists had a considerable presence in the sediments over time. Third, EcoQ indices tended to reflect PTSs contamination in the region. Finally, ratio-to-mean values obtained from the aforementioned three LOEs indicated that quality of sediments from the outer region of the bay had recovery more during the period of 16-years than did the inner region. Overall, the results showed that even with the progress supported by recent efforts from the Korean governmental pollution control, PTSs remain a threat to local ecosystem, especially in the inner region of Masan Bay.

Assessment of potential biological activities and distributions of endocrine-disrupting chemicals in sediments of the west coast of South Korea.

The west coast of Korea has experienced environmental deterioration for more than half a century. In the present study, we specifically aimed to: i) evaluate potential toxicities of contaminants in sediments that cause effects mediated through the aryl hydrocarbon receptor (AhR) and estrogen receptor (ER); ii) determine spatio-temporal distributions of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs); and iii) identify causes of greater potencies of samples. From 2010 to 2014, sediments were collected from 12 major estuarine and coastal regions along the west coast of South Korea. In vitro cell bioassays were performed to determine AhR- and ER-mediated potencies using H4IIE-luc and MVLN cells, respectively. Fifteen PAHs and six APs in sediments were identified by GC/MSD. Results of bioassays generally showed a low-to-moderate degree of contamination, however, greater AhR- and ER-mediated potencies were measured at some locations. Concentrations of PAHs and APs varied among locations, which indicated that sources were independently affected by the surrounding environment (e.g., industrial complex and cities). Results of bioassays were generally well correlated with concentrations of putative causative chemicals. Benzo[k]fluoranthene, dibenz[a,h]anthracene, and benzo[b]fluoranthene were the major AhR agonists, explaining approximately 30% of the bioassay-derived benzo[a]pyrene equivalent concentration (BaP-EQ). Unknown AhR and ER agonists and potential mixture effects remain in question. Overall, the present study provides baseline information on chemical contaminations and potential toxicity of sediments in a fairly wide geographical region of the west coast of South Korea.

Large-scale monitoring and assessment of metal contamination in surface water of the Selenga River Basin (2007-2009).

An extensive and year-round survey was conducted to assess metal pollution in vast watershed areas of the Selenga River Basin (2007-2009), which provided baseline heavy metal database for the future management. Sources and environmental hazard and risk indices associated with metal pollution were evidenced across the countries of Mongolia and Russia (Buryatia Republic). In general, the concentrations of heavy metals in river water of Mongolia were greater than those of Russia, expect for the upstream of the Dzhida River in Russia. The spatial distribution generally indicated that metal pollution in the Selenga River was mainly associated with the activities in the Mongolian upstream regions. Similar pollution sources of metals between river water and wastewater associated with surrounding activities were found across the industrial and mining areas. Compositional patterns of metals suggested their sources were independent of each other, with hot spots in certain sites. Our measurements indicated that about 63 % of the locations surveyed (48 of 76) exceeded the critical heavy metal pollution index of 100, identifying possible harmful effects on aquatic ecosystems through metal pollution. Zinc was found to be the chemical of priority concern, as more than half of the locations exceeded the corresponding water quality guideline. Other metals including Mn, Fe, Cr, Cu, and As might be problematic in the Selenga River Basin considering the occurrence and their concentrations. Results of our extensive survey during the period of 3 years indicated that urgent action would be necessary in timely manner to improve water quality and mitigate the impact of heavy metals on aquatic environment of the Selenga River Basin.

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.

Ecological risk assessment of arsenic and metals in sediments of coastal areas of northern Bohai and Yellow Seas, China.

Distributions of arsenic and metals in surface sediments collected from the coastal and estuarine areas of the northern Bohai and Yellow Seas, China, were investigated. An ecological risk assessment of arsenic and metals in the sediments was evaluated by three approaches: the Sediment Quality Guidelines (SQGs) of the United States Environmental Protection Agency (USEPA), the degree of contamination, and two sets of SQGs indices. Sediments from the estuaries of the Wuli and Yalu Rivers contained some of the greatest concentrations of arsenic, cadmium, copper, mercury, lead, and zinc. Median concentrations of cadmium and mean concentrations of lead and zinc were greater than background concentrations determined for the areas. All sediments were considered to be heavily polluted by arsenic, but moderately polluted by chromium, lead, and cadmium. Current concentrations of arsenic and metals are unlikely to be acutely toxic, but chronic exposures would be expected to cause adverse effects on benthic invertebrates at 31.4% of the sites.

Exposure and effects assessment of resident mink (Mustela vison) exposed to polychlorinated dibenzofurans and other dioxin-like compounds in the Tittabawassee River basin, Midland, Michigan, USA.

Historically, sediments and floodplain soils of the Tittabawassee River (TR; MI, USA) have been contaminated with polychlorinated dibenzofurans (PCDFs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated biphenyls (PCBs). Median concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) based on 2006 World Health Organization tetrachlorodibenzo-p-dioxin toxic equivalency factors (TEFs) in the diet of mink (Mustela vison) ranged from 6.8 x 10(-1) ng TEQ/kg wet weight upstream of the primary source of PCDF to 3.1 x 10(1) ng TEQ/kg wet weight downstream. Estimates of toxicity reference values (TRVs) derived from laboratory studies with individual PCDDs/PCDFs and PCB congeners or mixtures of those congeners, as well as application of TEFs, were compared to site-specific measures of mink exposure. Hazard quotients based on exposures expressed as concentrations of TEQs in the 95th percentile of the mink diet or liver and the no-observable-adverse-effect TRVs were determined to be 1.7 and 8.6, respectively. The resident mink survey, however, including number of mink present, morphological measures, sex ratios, population age structure, and gross and histological tissue examination, indicated no observable adverse effects. This resulted for multiple reasons: First, the exposure estimate was conservative, and second, the predominantly PCDF congener mixture present in the TR appeared to be less potent than predicted from TEQs based on dose-response comparisons. Given this, there appears to be great uncertainty in comparing the measured concentrations of TEQs at this site to TRVs derived from different congeners or congener mixtures. Based on the lack of negative outcomes for any measurement endpoints examined, including jaw lesions, a sentinel indicator of possible adverse effects, and direct measures of effects on individual mink and their population, it was concluded that current concentrations of PCDDs/PCDFs were not causing adverse effects on resident mink of the TR.

Nondestructive scat sampling in assessment of mink (Mustela vison) exposed to polychlorinated dibenzofurans (PCDFs).

The mink (Mustela vison) is often utilized as a sentinel species for ecological assessments at sites where contaminants of concern include dioxins and dioxin-like compounds. Utilizing mink scat as a nondestructive tool to determine internal exposure to dioxin-like compounds may allow for rapid, accurate estimates of exposure without the need to capture mink or their prey. To determine the relationships between concentrations of polychlorinated dibenzofurans (PCDFs) in tissues (liver and adipose) and those in scat, mink were fed PCDFs in scat during a controlled laboratory study for 180 days. Mink were fed a control diet, diets with three doses of 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PeCDF) or 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF), and a diet with an environmentally relevant mixture of the two congeners. Concentrations of PCDFs in liver and adipose were measured after 0, 90, and 180 days of exposure. Concentrations of the two PCDF congeners in mink scat were determined after 2, 23, 45, 90, and 180 days of exposure. Concentrations of both PCDF congeners in scat were significantly correlated with those in liver and adipose tissue (r(2) = 0.94-0.97, p < 0.01). This indicates that measurements of concentrations of both PCDFs in scat can be used to predict concentrations of PCDFs in liver and adipose. Assimilation and elimination characteristics of 2,3,4,7,8-PeCDF or 2,3,7,8,-TCDF and a mixture of the two congeners by mink could be predicted from concentrations of these congeners in scat. Overall, concentrations of PCDFs in mink scat can be used as a rapid and inexpensive nondestructive method to predict concentrations of PCDFs in mink when certain assumptions are met.