Microplastics have received widespread attention as an emerging contaminant, but limited information was available during wetland restoration. The occurrence and characteristics of microplastics and their interaction with heavy metals in surface sediments from the Jinjiang Estuarine restored mangrove wetland were investigated. The abundance of microplastics ranged from 490 ± 127.3 to 1170 ± 99.0 items/500 g dry sediment, and the restored regions were much higher than mudflats, indicating mangrove restoration promoted its accumulation. Polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) were the main materials of microplastics after Raman spectroscopy identification. SEM-EDS images illustrated the mechanical erosion and chemical weathering on microplastics' surface, and Cr, Zn, Pb, and Cd were observed in elemental composition. The contents of Cr, Ni, Cu, Zn, Pb, As, and Cd accumulated in microplastics were not correlated with their total concentrations in sediments except for Hg, indicating that they might not be derived from sediments.

The Lumparn Bay, due to its nature, is prone both to natural and anthropogenic environmental pressures. It is a semi-enclosed rather large, but relatively shallow bay filled with glacial and postglacial sediments. Unlike any other areas in the world the seafloor in this area is filled with gas domes. Comparison with the chemistry of some 2000 surface core samples from the Gulf of Finland revealed that the concentrations of arsenic, cadmium, chromium, copper, mercury, molybdenum, nickel, lead, zinc, and sulphur from the Lumparn Bay were in general on a low level, indicating only minor pressures on the seafloor. However, when compared to established sediment quality guidelines there are a few points of possible concern as some samples exceed the probable effects level for arsenic and quite a few samples exceed the effects range – median level for nickel. Also a few comparably high molybdenum concentrations exceed the lowest effects level.

The effects of two harmful algae Alexandrium tamarense and Gymnodinium catenatum on ecological quality status were identified using biofilm-dwelling ciliate assemblage as test organism communities. The body-size spectra of the test ciliates were observed at a gradient of cell concentrations of both algal species: 10⁰ (control), followed by10², 10³, 10⁴ and 10⁵ cells ml⁻¹. The test ciliates showed clear variations in body-size spectra along the concentration gradients of both algal species. In terms of probability density, the ciliates generally peaked at low levels of algal concentrations (10⁰–10⁴ cells ml⁻¹) in small size forms, followed by the forms with large sizes at the concentration of 10⁵ cells ml⁻¹ of both algal species. Bootstrapped-average analysis demonstrated a significant change in body-size spectrum when algal concentrations were higher than 10⁴ cells ml⁻¹. It is suggested that the body-size spectrum of the ciliates may be used to indicate the effects of harmful algal bloom.

This study delineates the impact of a man-made hydrological barrage [Thannermukkom barrage (TB)] on the concentration of selected trace metals (Fe, Zn, Cu, Co, Cr, Mn, Ni, Pb) in mesozooplankton from the Kochi backwaters (KBW). The overall results point out that during Pre-Southwest Monsoon (PRM), the concentration of trace metals in mesozooplankton was high in the upstream due to the closure of the barrage, which essentially causes stagnancy of the waters. Trace metal concentrations in the downstream and upstream regions of KBW were found to be lower during Post- Southwest Monsoon (PSWM) compared to the rest of the seasons. In general, trace metals in mesozooplankton from the KBW showed the following order of concentration: Fe > Mn > Zn > Ni > Cu > Cr > Co > Pb. A comparison with earlier data across the globe showed that trace metal concentration in mesoplankton in the KBW is lower than the values reported from other parts of the world.

The largest-scale green tides in the world caused by Ulva prolifera have been recurring annually in the Southern Yellow Sea since 2007. In this study, spatio-temporal variations of green tides and nutrients were investigated in the spring and summer of 2017, and the roles of different nutrients in the development of green tides are discussed. The results showed that the development of green tides could be divided into two parts according to the distinct growth phases of green tides: (1) the development area (DA), which was located south of 35°N and characterised by the quick expansion of green tide and high-content nutrient; (2) the accumulation area (AA), which was located north of 35°N and characterised by high U. prolifera coverage area and low-content inorganic nutrients. Through calculation of nutrient reductions, we found that DA provided 96% of nitrogen and 87% of phosphorus for the development of green tides in 2017, and the dominant nutrient species were dissolved inorganic nitrogen and dissolved organic phosphorus. Regarding AA, the dominant nitrogen component was dissolved organic nitrogen. Thus, we conclude that reducing the level of nutrient input in order to alleviate the eutrophication of seawater in the Jiangsu coastal area may be an important measure for reducing the scale of green tides.

Plastic litter in nearshore waters is an environmental pollutant with increasing impact on coastal environments. At present, knowledge on basic plastic particle dynamics and the interaction with complex hydrodynamics is lacking. The present laboratory study, performed under controlled wave and wind conditions, demonstrates the dispersion of plastics in shallow waters. The study presents a simple case looking solely at cross-shore particle transport. The results show that both wind and waves as well as plastic properties (shape and density) govern the behaviour of plastic litter in the nearshore zone. Heavy particles behave like natural sand with accumulation in the wave breaking zone. Light particles have varying accumulation along the coastal profile depending on the wind, waves and particle shapes. More extensive characterization remains to be done in future studies.

Previous studies indicate coastlines are at risk of wastewater contamination from injection wells, cesspools, and septic systems. In this study, common marine algae were used to ground-truth modeled loading of wastewater-derived N to coastlines of Oʻahu, Hawaiʻi. Macroalgae were collected and/or deployed at 118 sites and analyzed for tissue δ¹⁵N and N %. Wastewater source locations were used to estimate wastewater-derived N in groundwater with the modeling software MT3DMS/MODFLOW. Algal bioassays identified six coastal regions subjected to elevated wastewater-derived N loading. In a case study, submarine groundwater discharge (estimated by ²²²Rn mass balance) was related to wastewater loading from onsite sewage disposal systems (OSDS) and municipal wastewater injection wells in Waimānalo. The highest ²²²Rn-derived SGD rate and N flux were 21.4 m³/m/d and 62.6 g/m/d, respectively. The results of this study suggest that OSDS and injection wells discharge substantial volumes of wastewater and N across broad regions of coastal Oʻahu.

PURPOSE OF REVIEW: Different selenium species released into the environment by anthropogenic activities pollute surface and ground water resources and can cause severe damage to the environment and ecosystems due to bio-accumulation. Though several physico-chemical methods are available to treat selenium oxyanion-containing wastewater, biological methods have gained significant importance due to their capability to convert selenium oxyanions to elemental selenium nanoparticles. The purpose of this review is to summarize the literature available on biological removal of selenium oxyanions and their recovery as elemental selenium nanoparticles. RECENT FINDINGS: In recent times, the capability of several bacterial and fungal strains to reduce selenate and selenite to form elemental selenium nanoparticles has been reported. The shape, size and location of these selenium nanoparticles along with the selenium oxyanion removal efficiency depend on the operating parameters. Moreover, bioreactor configurations and operation strategies greatly influence the selenium removal and recovery efficiency. Several conventional bioreactor systems can be used to remove selenate and selenite from wastewater and form selenium nanoparticles. However, the selenium nanoparticles are mostly entrapped in the biomass and require a secondary treatment to recover them. On the other hand, some novel bioreactors, viz. inverse fluidized bed bioreactor, rotating biological contractor, horizontal rotating packed bed bioreactor, moving bed biofilm reactor, and hybrid bioreactor, can possibly recover selenium nanoparticles following bioreduction of selenium oxyanions in a single stage system. Thus, this review will help in finding research gaps in this area and providing solutions for resource recovery from selenium oxyanion-containing wastewater.

Plastic pollution has become a major environmental concern worldwide, and marine ecosystems have become polluted with ubiquitous microplastic particles (MP). MP can contain chemical additives and can also scavenge pollutants from the surrounding environment, and these co-contaminants may threaten the marine biota when MP become inadvertently ingested and transferred up the food chain. However, our understanding of the sorption-desorption kinetics of chemical compounds bound to MP remains limited. Moreover, whether MP are better transport vectors of co-contaminants than other natural particles (e.g. sediment) has not received much attention. Here, we used radiotracers to examine the partition coefficients (Kd) of three trace metals (¹⁰⁹Cd, ¹³⁴Cs, and ⁶⁵Zn) to virgin MP (32–75 μm polyethylene beads) and to natural sediment particles of a similar size (35–91 μm) in seawater. After 72 h, sediment particles adsorbed 2.5% of ¹⁰⁹Cd, 68.0% of ¹³⁴Cs, and 71.0% of ⁶⁵Zn, while MP adsorbed <0.8% of these three elements. Results highlight that under these experimental conditions, virgin polyethylene MP may not be effective transport vectors for these trace metals. Important variations in Kd were observed between elements, inciting for further studies to decipher how chemical characteristics, MP composition, and associated-biofilms, all interact in these biokinetic processes. These results demonstrate how radiotracers can allow us to address important knowledge gaps and broaden our understanding regarding the interactions between waterborne contaminants, naturally occurring particles and marine wildlife.

In this study, we aimed to identify impacts of plastic ingestion by the ecologically important rocky shore crab Pachygrapsus transversus. We sampled individuals from August 2019 to January 2020 in a reef environment and determined their body condition and diet diversity. In order to test our hypothesis that plastic retention in the foregut is able to decrease the condition factor, we compared it between contaminated and non-contaminated individuals. A correlation test of number of ingested plastic fibres against trophic diversity was made to corroborate the hypothesis that plastic ingestion modifies the feeding patterns. Our results demonstrated that contaminated individuals had lower body condition. Also, we confirmed that debris ingestion can influence feeding patterns. These outcomes were probably linked to starvation and nutrient loss effects. We discussed that this crab is a potential sentinel specie for addressing impacts of solid pollution and a candidate for monitoring plastic contamination in reef environments.