Although the simplification of multivariate histopathological data into univariate indices can be useful for the assessment of environmental quality, this implies a great loss of information. The objective of the present study was to evaluate the effectiveness, in the context of environmental quality assessment, of an approach that integrates individual histopathological responses in a discriminated manner with the results of contaminants by means of multivariate analyses. This analysis was compared to the diagnosis of environmental quality provided by the use of the univariate Bernet histopathological index. Contaminant loads (sediments and fish) and the liver histopathology of Cathorops spixii were integrated through multivariate analysis. Integrated individual histopathological responses allowed classifying environmental quality from more to less impacted sites, while the univariate index showed some inconsistencies with chemical loads and allowed identifying only the most impacted site.

PURPOSE OF REVIEW: This paper reviews recent advances in a membrane bioreactor (MBR) and focuses on the features and performance of MBR configurations. Special attention is given to MBR configurations developed for improving pollutant removal and fouling control. RECENT FINDINGS: The first development discussed in this review is related to pollutant removal. Modified MBR configuration can enhance pollutant removals, such as those observed in baffled, osmotic, aerobic granular sludge, and electric field-assisted MBR. In addition, fouling is still the major problem in MBR applications. Fouling affects membrane performance stability as well as operational and capital costs. Several new MBR configurations have been developed to address fouling issues. By using dynamic membrane and free-moving particles, these new configurations make MBR operation more stable with fewer cleaning operations. In addition, lower cleaning frequency will decrease operational expenditure and capital investment. Due to their unique features, newly developed MBR configurations are proved to display high pollutant removal in wastewater treatment. Meanwhile, MBR with dynamic membranes and moving particles can decrease membrane fouling due to mechanically induced shear with lower energy consumption than shear by conventional aeration.

Microplastics pretreatment of prior to biodegradation is an efficient approach for their bioremediation. We isolated Achromobacter denitrificans from compost and used it for biodegradation of thermo-oxidative pretreated polyvinyl chloride (PVC) and low-density polyethylene (LDPE). About 12.3 % and 6.5 % weight loss, and 326.4 and 112.32 mg L⁻¹ extracellular protein were observed in bacterial flasks with PVC and LDPE, respectively. The pH in treated PVC reached to 5.12 and the thermal stability increased by 29 °C. The chemical modification in LDPE was demonstrated through oxidation of antioxidants (Phenol group), formation of new groups (Aldehyde group), and chain fracture in the main backbone by Fourier transform infrared spectroscopy. Formation of peaks at the range of 1700–1850 cm⁻¹ in LDPE attributed to formation of carbonyl groups as the degradation result. Scanning electron microscopy confirmed LDPE and PVC degradation by surface alterations. Consequently, thermo-oxidative pretreatment can be considered as a suitable strategy for improving microplastics biodegradation.

The structural characteristics of phytoplankton communities and their relationship with environmental factors were analysed based on survey data from the central South China Sea in summer 2020. A total of 416 separate taxa from 90 genera and 4 phyla were identified, with an average cell abundance of 572.98 cells/L. The dominant phytoplankton species were Nitzschia spp., Gyrodinium spp., Synedra spp. and Navicula spp. The Shannon-Wiener index ranged from 2.25 to 4.98, and the evenness index varied from 0.48 to 0.93. Correlation analysis showed that total cell abundance was negatively correlated with salinity, nitrate and silicate and was positively correlated with nitrite. Compared with the historical data, Thalassionema nitzschioides was cited repeatedly in previous researches as the dominant species. In addition, the Shannon–Wiener index showed an overall increasing trend over time, and the community structure is becoming more stable.

During the COVID-19 pandemic, face masks became a common type of litter invading many different environments, including tourist beaches. However, the presence of face masks on beaches threatens the marine environment with a new form of plastic pollution. In this study, we monitored the occurrence and density of face masks on five tourist beaches along the Moroccan Mediterranean during five months starting from February until June 2021. A total of 321 face masks were recorded on the five beaches, 96.27% of which were single use. The mean density of face masks was 0.0012 ± 0.0008 m⁻². Recreational beaches were the most polluted in the study area. This is related to the important influx of beachgoers on urban beaches compared to resort beaches. With the large number of masks introduced on the beach, we hypothesize that microplastic pollution could increase drastically in the Moroccan Mediterranean in the coming years. Significant efforts are required to reduce this type of waste.

Harmful algal blooms (HABs) have induced severe damage worldwide. A novel high-efficient antialgal natural chemical, 3-indoleacrylic acid (3-IDC) with a 5-day half-maximal inhibitory concentration (IC₅₀, ₅d), was discovered from canola straw, and its algal inhibition mechanism was investigated. Adverse effects were observed on the growth of P. donghaiense with 3-IDC addition, following an increase in reactive oxygen species (ROS) production. 3-IDC also hindered the photosynthetic mechanism of P. donghaiense cells. Transcriptional results showed 3-IDC inhibiting the functions of all the nutrient assimilating genes, down-regulated ribulose-1,5-bisphosphate carboxylase/oxygenase II, and cytochrome f genes. The expression of heat shock protein (HSP) 70 and 90 and rhodopsin genes were also suppressed. The binding affinity of investigated receptors was observed. The conformational changes induced by the spatial microstructural alteration through 3-IDC may further contribute to the perturbation of those enzyme catalytic activities. The present results provide new insights on controlling HABs using 3-IDC.

The combined effects of copper and polyvinyl chloride (PVC) microparticles were investigated on the metal accumulation, histopathological biomarkers, and targeted transcriptomics in Cyprinus carpio liver. The fish were exposed to 0.25 mg/L copper and/or 0.5 mg/L PVC microparticles over a 14-d period. The results showed that hepatic copper accumulation is facilitated by the PVC microparticles presence in water. All treatments induced significant hepatic stress and inflammation; however, the transcriptional responses involving in detoxification pathways and apoptotic mechanisms were mixed and often down-regulated in the fish exposed to copper and/or PVC microparticles. Exposure to copper and/or PVC microparticles induced hypermeia, leukocyte infiltration and increase in melanomacrophage centers number and area. Generally, the severity of the lesions was in the following order: PVC microparticles < copper < copper+ PVC microparticles. In conclusion, PVC MPs act as a copper vector, facilitating accumulation of copper in the fish liver and increasing the tissue damage.

Possible access routes of macro and mesoplastics, acting as the main sources of pollution in the coastal ecosystem, are examined as a case study on four beaches along the Istanbul coast. A total number of 3787 items belonging to 12 categories of debris types were collected as follows: macroplastics 47.8%; mesoplastics 9.2%; and others 43.0% such as paper pieces, glass pieces and metal beverage cans. Clean-coast and carbonyl indexes were also used to identify the level of cleanliness of the sampling sites. The clean-coast index revealed that all of the sample sites were categorized as extremely dirty. Moreover, carbonyl index results indicate that 35.7% of the samples were at a high oxidation level indicating that some of the particles relatively spend more time on beaches. The litter concentration and surface oxidation results were addressing issues that should be taken into consideration to improve litter management strategies of the beaches.

The world production of farmed Whiteleg shrimp was 5,812,180 t in 2020. Ecuador, Mexico, and Brazil produced 1,012,830 in that year according to data FishStatJ. Environmental impact studies were scarce given the rapid growth of this activity, mainly on cummulative impacts, loss of ecosystems services or resilience of wetlands and mangroves. Aspects of the management of environmental impacts published on American studies during 1986–2020 are analyzed. The main impacts included the loss of mangroves and their transformation of these ecosystems and their water bodies by receiving enriched effluents from shrimp farms. Different management measures are discussed between Ecuador, which contributes 63.76 % of American production of white leg shrimp; Brazil which published 46.2 % of the environmental studies of the analyzed period, and Mexico, in an intermediate situation. Finally, alternatives are discussed to improve the management of shrimp aquaculture with emphasis on the Ecuadorian context.

In this study selected marine species from north Persian Gulf ecosystems were collected to investigate the concentration of 15 trace elements (Al, As, Co, Cr, Cu, Fe, Li, Mo, Ni, Pb, Se, Sr, V, Zn and Hg) in muscle and liver tissues for the purpose of evaluating potential health risks for human consumers. The results indicated that Fe, Zn, Sr, Cu and As are the most abundant TEs in the tissues of the species. The concentration of Cu in P. semisulcatus and As in most investigated species pose the highest risk of exposure. The carcinogenic risk values indicate that As and Ni concentrations in the species are above the acceptable lifetime risk for adults and children in most of the species. The margin of exposure risk approach indicated that the risk of detrimental effects due to dietary Pb intake for age groups is low, except for consumers of T. tonggol.