We investigated the composition, source, and reactivity of sedimentary organic matter (OM) present in aquaculture systems along the Korean coast. A multi-isotopic approach was applied to 216 surface sediments from five sections: western (W)-1, W-2, southern (S)-1, S-2, and eastern (E)-1 sections. The ¹⁵N-enriched total nitrogen signatures in the surface sediments of the W-1 section may indicate that a substantial fraction of sedimentary OM has anthropogenic origins exported through the Han River. Simultaneously, the deposition of allochthonous OM is predominant in the S sections (Jinhae and Masan Bays). The ³⁴S-depleted patterns at the S-2 section may indicate that sulfate reduction occurring at the sedimentary boundary contributes to active OM decomposition, depending on the increased sedimentation of the aquaculture-derived OM. Our results highlight that isotopic-based source tracking near aquaculture systems provide important information for identifying anthropogenic contamination in coastal marine sediments and for improving environmental management.

PURPOSE OF REVIEW: Organic solid wastes (OSWs) have great potential for resourceful applications. However, individual treatment technologies are difficult to effectively recover their resources. This review aims to describe the development of solid-state anaerobic digestion (SS-AD), digestate aerobic composting, and their hybrid technology (SSADAC) for OSWs treatment to maximize resource recovery from OSWs. RECENT FINDINGS: SSADAC exhibits high potential for OSW treatment in energy and nutrient recovery. As individual treatment technologies, SS-AD and digestate composting recover energy and nutrients in terms of methane and compost, respectively. However, some deficiencies of these individual treatment technologies are hard to be ignored, such as energy loss and liquid digestate/leaching discharge. SSADAC can alleviate these issues with fully synergizing the characteristics of two treatment units for multi-target products. Thus, recent studies have proposed that the regulation of digestion duration can improve SSADAC performance, and other potential methods can also improve the value of SSADAC, such as raw material regulation and exogenous additives, to achieve zero waste discharge and maximum resource recovery. This review presents the applications of SS-AD and digestate composting for OSW treatment and illustrates the development and potential improvements of SSADAC as an integrated process. Key issues and their potential counter-measurements were displayed to provide the further development of SSADAC.

Eleven heavy metals (V, Cr, Mn, Co, Fe, Ni, Cu, Zn, As, Cd, and Pb) in surface sediment in the intertidal zones of the Yellow River Estuary, China were analyzed by inductively coupled plasma-mass spectrometry in summer and autumn 2019. Results indicated that the 11 heavy metals had the same sources. Sediment particle size and total organic matter were the main factors influencing the distribution of heavy metals. Most sites in the intertidal zones of the study area were not contaminated with V, Cr, Fe, Co, Zn, Pb, Cu, As, Mn and Ni, while Cd was the priority pollutant. Heavy metal pollution risk in autumn was higher than that in summer, which may be due to hydrodynamic effects. The present study showed that the heavy metal concentrations in the study area had a temporal decreasing trend compared to previous studies, which may be due to the reduction in human activities.

The tidal influence on body-size spectrum of the protozoan periphytons was explored by using the conventional slide system (CS) and the polyurethane foam enveloped slide system (PFES) in coastal waters during a 1-month study. During the colonization process, clear temporal patterns of the body-size spectrum were observed using the two sampling methods. In terms of relative species number and frequency of occurrence, the rank S4 represented a more stable temporal variability in the PFES system than the CS system during the colonization. Additionally, the small forms (e.g., S1, S2, and S3) were more abundant in the PFES system. The clustering and bootstrapped average analyses demonstrated differences in body-size spectrum of protozoans between the two sampling systems. Our results imply that the body-size spectrum of protozoan periphytons may be impacted by tidal events during colonization process in marine waters.

The quantification of macroplastic fluxes transferred by rivers toward the pelagic environment requires a better understanding of macrodebris transfer processes in estuarine environments. Following the strategy adopted in the Seine estuary, this study aims to characterize macroplastic trajectories in the Loire estuary. Between January 2020 and July 2021, 35 trajectories were monitored using plastic bottles equipped with GPS-trackers. With total travelled distances between 100 m and 103.6 km, trajectories show great spatiotemporal variability. The various forcing factors (macroplastic buoyancy, estuaries tidal and hydrometeorological conditions, geomorphology and vegetation) lead to chaotic trajectories, preventing accurate predictions in macroplastic transfer and storage/remobilization dynamics. In the Loire estuary like in the Seine one, no tracked bottle reached the Atlantic Ocean. It confirms that macrotidal estuaries under temperate climates constitute accumulation zones and slow pathways for macroplastics, but raises question on the real fluxes transferred from continental areas to oceans.

Three ²¹⁰Pb-dated sediment cores were used to evaluate the contamination degree and flux ratios of potentially toxic elements (PTEs; As, Cd, Cr, Cu, Ni, Pb, V, and Zn) in seagrass meadows from the northern margin of Términos Lagoon (TL), southern Gulf of Mexico. The sediments displayed minor Cd, Ni, V, and Zn enrichments but moderate to strong enrichment by As. Results from a chemometric analysis revealed that: 1) salinization and grain size, along with 2) the terrigenous inputs are the major factors influencing the PTEs accumulation. The historical trends of PTEs flux ratios nearly follow the large-scale land-use changes around TL, linked to the growth of the Mexican oil industry in the area since the 1970s. Our findings showed the critical role of seagrass meadows as PTEs sinks. This information is useful for decision-makers to develop restoration projects for a vulnerable site within the largest coastal lagoon ecosystem in Mexico.

Total mercury (T-Hg) was examined in 8 threadfin bream species (Nemipterus spp.) caught in the Gulf of Thailand (GoT). The T-Hg contents ranged from 11.3 to 374 μg kg⁻¹ wet weight, with the lowest in Nemipterus peronii and the highest in Nemipterus nemurus and Nemipterus tambuloides. Accumulation of T-Hg in fish tissue was found to be related to fish size, trophic levels, feeding habits and habitat. Threadfin bream caught in the upper GoT exhibited significantly (p < 0.05) lower T-Hg than those in the middle and lower parts of GoT, which possibly due to local mercury sources e.g., internal anthropogenic activities in the GoT and external from terrestrial input via river discharge. The estimated daily intakes were ranged from 0.03 to 0.07 μg kg⁻¹ bodyweight day⁻¹. All threadfin breams in the GoT have HQ <1. To prevent the associated potential risk, the maximum safe daily consumption is recommended at 95.3 g day⁻¹.

With several observable responses and sensitivity of protozoans to nitrofurazone (NFZ), the toxic effects of NFZ on protozoans can be an early warning signal of NFZ contamination in the aquatic environment. To evaluate the toxic dynamics induced by NFZ, protozoan samples were collected using microscopy glass slides and exposed to the five concentrations of NFZ: 0, 1, 2, 4, and 8 mg ml⁻¹. Substantial differences in the species composition and toxic-dynamics patterns were observed among all concentrations. Briefly, periphytic euplotids and pleurostomatids were the most prevalent at each concentration level, while dysteriids were less dominant among all treatments. Multivariate analysis revealed significant (P < 0.05) differences in the taxonomic patterns of the test organisms among the five treatments. Furthermore, significant deviation of protozoan communities from the expected taxonomic breadth was observed to occur in a dose-dependent manner. Based on these findings, it is suggested that protozoan periphytons could be used as bioindicators to assess the ecotoxicity of NFZ in the marine environment.

The last decades have shown that human activities damaged environmental quality and biodiversity. As accepted the need of sustainable development, there should be balance between economic, social and environmental issues in the long term. Ecological footprint is an important indicator that shows how human activities reduce environmental quality among a specific region or country. In addition, human capital is mostly used indicator to estimate economic and environmental development level. In this study, it is aimed to explore the effect of human capital on fishing footprint for 10 Mediterranean Countries during the period 1995–2018. According to empirical evidences, it is concluded that for relatively low human capital level, human capital has negative effect on sustainability and in the relatively high level, it has positive effect on sustainability.

Potassium hydroxide (KOH) digestion protocols are currently applied to separate microplastics from biological samples, allowing efficient digestion with minor degradation of polymers in a time- and cost-effective way. For biota samples with high-fat content, KOH reacts with triglycerides generating an overlying soap layer, making difficult the digestion and solubilization and subsequent microplastics extraction. Here we studied the addition of Tween-20 in different concentrations to evaluate the effect on the soap layer of post-digested samples. Addition of 10 % of Tween-20 presented higher flow rate during filtration, being set as optimal value. Incorporation of Tween-20 in the extraction procedure increased recovery rates of LDPE, PC and PET and appears to have a protective effect on PC and PET degradation. Tween-20 did not interfere in FTIR spectrum of polymers available in the marine environment. Being low-toxic, makes addition of Tween-20 a simple and economical way to optimize KOH digestion protocols for microplastics extraction.