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.

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.

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.