The pollution of the Siberian Arctic seas bottom by anthropogenic debris is assessed for the first time based on the results of bottom trawl surveys conducted in the Chukchi, East Siberian, Laptev, and Kara seas in 2019. In the East Siberian Sea and the Laptev Sea, no seabed litter was detected. The debris on bottom and near bottom was found in the Kara and Chukchi seas only. Plastic was the most frequently occurring type of seabed litter. The main source of the garbage encountered in the Kara Sea is the waste related to fishing activities in the Barents Sea.

During 2015–2020, 26 cruises were carried out in a bay scallop farming area, North Yellow Sea, to study the dissolved oxygen (DO) dynamics and its controlling factors. Significant DO depletion (deoxygenation) was observed in the summertime with the decrease rates of 0.31–0.55 and 0.96–2.10 μmol d⁻¹ in the surface and bottom waters, respectively, which were comprehensively forced by temperature, photosynthesis and microbial respiration. Seasonally, temperature was the main driver of the deoxygenation processes. In the surface water, DO dynamics were dominated by temperature-induced solubility changes, while the photosynthesis offset the effects of physical processes to a certain extent; in the bottom water, its dynamics were mainly attributed to the comprehensive control of temperature-induced solubility changes and biological respiration. Overall, the results suggested that the occurrence of hypoxia and acidification in the coastal waters were highly associated with the formation of temperature-induced stratification under complex hydrodynamic processes.

A yearlong seasonal survey was carried out during 2016–2017 at 26 stations representing four tidal channels of the north-western part of the Gulf of Gabès (Tunisia). The area studied (characterized by a maximum tidal range of 2.3 m) was subjected to diverse anthropogenic pressures: from the phosphate industry and its metallic pollution, unauthorized bottom trawling in shallow water (known locally as ‘Kiss’), and organic pollution from the nearby urbanized areas. A total of 23,506 invertebrates representing 311 taxa were collected. Dominant taxa were the polychaetes with 51.4% of the individuals collected and 39.3% of the taxa, the amphipods (18.6% and 15.5%), the tanaids (12.3% and 2.6%), and the molluscs (11.5% and 18.3%). The mean annual abundances varied widely from one channel to another: from 300 to 3700 ind·m⁻². The stations located in deeper waters exhibited greater variability. Measurements of abundance revealed seasonal changes with maximum values in winter, spring, and lower numbers in summer. Each tidal channel was characterized by specific features in the fauna. The macrofauna were dominated by the polychaete Cirratulus cirratus (mainly in spring) and the amphipod Microdeutopus anomalus (mainly in winter), whilst both of the tanaids, Apseudopsis gabesi (the first sighting reported for the area) and A. mediterraneus, were found to be abundant in winter in at least one of the four channels. Species are mainly deposit feeders, herbivorous and omnivorous. The analyses on spatial and temporal changes of the macrofauna population revealed variations according to the composition of the fauna increasing or falling along the channels and as a function of seasonal changes. In spite of a high level of anthropogenic activities, the Ecological Status (ES) assessment (applying the AMBI and M-AMBI indices) attributed High or Good ES for 10 stations, Moderate ES for 11 stations and five stations showed a poor ES at least during one season. Sampling subtidal stations in the future to survey long-term degradation of such ecosystems of the coastal environment of the Gulf of Gabès in Tunisia is proposed.

The anthropogenic marine debris in the Mediterranean Sea represents a growing concern because of its potentially harmful impact on marine ecosystems. In this paper, we investigated the composition of marine debris in the Iskenderun Bay seafloor. Between November 2009 and April 2010, a total of 34 trawl operations were conducted. Hauls lasted 60–385 min, and the towing speed varied between 2.7 and 2.8 knots. The estimated average marine litter concentration was 450.94 item/km² (90.34 kg/km²). Plastic was the dominant material type (87%) at all stations. Single-use plastic items represented about 74.9% of the total marine litter. Our results showed that there is severe plastic pollution on the seafloor of Iskenderun Bay that may cause significant damage to both the fisheries sector and the marine environment.

The effects of two harmful algal bloom (HAB) species Alexandrium tamarense and Gymnodinium catenatum on ecological quality status were studied using 14-day protozoan samples as test organisms. A fuzzy coding system with four traits and 11 categories of the test organisms was used for biological trait analysis. Five treatments were designed following the concentrations of 10⁰, 10², 10³, 10⁴ and 10⁵ cell ml‐¹ of each algal species. The community-weighted means were used to summarize the functioning process of the test organism assemblages. The community functioning of the protozoa showed a significant change in the treatments with high algal concentrations (10⁴ and 10⁵ cell ml⁻¹). The functional richness of the test organisms showed continuous increasing trend from 10² to 10⁴ cell ml⁻¹, and sharply dropped. These findings suggest that the BTA may be used as a useful tool for assessing the effects of HABs on ecological quality status in marine ecosystems.

In the event of an oil spill, emergency responders must quickly deploy cleanup and protection equipment using guidance provided by a forecast trajectory. Forecasting the location of the surface oil over time is standard practice; however, current performance metrics used for assessing the quality of the spill forecast lack both an appropriate numerical model accuracy score and specification of the expected spatial resolution limit for useful forecast information. This paper adapts the Fractions Skill Score method, commonly used in weather forecasting, to oil forecasting. A subset of satellite images and trajectory forecasts from the Deepwater Horizon oil spill are used as an example of the method.

PURPOSE OF REVIEW: Hydrothermal carbonization (HTC) is an innovative technique by which a wet feedstock is converting into valuable product, hydrochar, without drying as a pretreatment step. Over all other thermal converting process, HTC is counted as the most cost-effective and environmentally friendly technique. The purpose of this review is to highlight the current research trends of HTC and the application of hydrochar derived from biomass in heavy metal removal. RECENT FINDINGS: This review provides an overview about HTC fundamentals including its ecotoxicology and the factors such as biomass type, reaction temperature, retention time, catalysis, and pH medium, which affect hydrochar composition and performance. Moreover, various modification agents in order to function the hydrochar was discussed. It is proposed that the co-hydrothermal carbonization of two or more biomasses with the addition of other materials can enhance the functional groups and change the features of the produced hydrochar. This paper also reviews the kinetic analysis and adsorption isotherm as well as the hydrochar applications in heavy metal removal. Acacia arabica waste is produced annually in huge amount, which adversely affect the environment. Up to now, it has no specific reuse in a proper way. In this respect, biomass such as Acacia arabica wastes can successfully be valorized by converting into hydrochar via hydrothermal carbonization. Moreover, application as a green adsorbent to remove heavy metal contamination from wastewater due to its high porosity and great surface area is counted as a promising technique that contributes to this field of research.

Blooms of the non-toxic dinoflagellate Prorocentrum donghaiense are common in the East China Sea; however, the in situ impacts of these blooms on zooplankton community functions have not yet been conducted in this area. Using functional trait-based methods, we found that P. donghaiense bloom significantly changed the zooplankton community structure and functions in the coastal water of the East China Sea. Zooplankton species richness and biodiversity increased after the bloom. Based on body length, feeding type, trophic group and reproductive mode, we categorized zooplankton into four functional groups and characterized their dynamics. Before and after the bloom, the zooplankton community was dominated by herbivorous- and free-spawner- lineages represented by copepods and tunicates, while during the bloom, the zooplankton community was dominated by carnivorous- and egg-brooding- lineages represented by small jellyfish, chaetognaths and copepods.

This study assessed the concentrations, sources, and risks of polycyclic aromatic hydrocarbons (PAHs) in sediments from the Rivers Niger, Ase and Forcados in the western Niger Delta. The concentrations of PAHs (in μg kg⁻¹ dry weight), as determined by gas chromatography–mass spectrometry, in sediments from these rivers varied from 2400 to 19,000, 2930 to 16,100, and from 1620 to 19,800 for the Niger, Ase and Forcados Rivers respectively. High molecular weight (HMW) PAHs were the most prevalent compounds present in these sediments. An assessment of the possible ecological and human health risks suggested high risks for both organisms and humans. The PAH source analysis suggested that sediments from these river systems were contaminated with PAHs arising from burning of biomass, gasoline/diesel emissions, burning of natural gas, and oil spillages.

This work presents the structural and functional traits of benthic amphipods in the Saudi waters of the Arabian Gulf. Sixty-two species belonging to 37 genera and 17 families were recorded. Sensitive species such as Grandidierella bonnieroides, G. exilis, Gammaropsis atlantica and Caprellidea indet., were mostly dominant. The average values of richness, density and diversity (H′ log₂) were 11 ± 1, 512 ± 232 ind. m-2 and 3.1 ± 0.1 respectively. The density decreased with increased in depth (nearshore (NS) - 784 ± 445 and offshore (OS) - 222 ± 28, p = 0.023), while evenness (NS – 0.93 and OS -0.94) and diversity (NS – 3.10 and OS - 3.18) were unaffected by depth. Interstitial space dwellers (56.76%) and surface deposit feeders (60.16%) were dominant in the nearshore sand substratum. However, domicolous (72.2%) with suspension and surface deposit feeders (71.7%) were more in offshore silt sediments. The combination of depth, pH and TPH (p = 0.249) influenced the distribution of amphipods.