To understand the transport of Fukushima Dai-ichi Nuclear Power Plant Accident (FDNPPA)-derived nuclear contaminated water, which will be discharged into the Pacific Ocean in the future, the distributions of ¹³⁴Cs and ¹³⁷Cs in seawater in the public areas east of Japan in winter 2011 were reported in this study. The ranges of ¹³⁴Cs and ¹³⁷Cs activities were <MDA (Minimum Detectable Activity) -68.9 Bq/m³ and 1.3–85.9 Bq/m³, respectively. The average decay corrected FDNPPA-derived ¹³⁴Cs/¹³⁷Cs activity ratio was 0.97. The FDNPPA-derived radiocesium existed in the seawater at a relatively high level at most stations. The ¹³⁴Cs and ¹³⁷Cs activities were comparable throughout the upper 50 m at each station. The FDNPPA-derived radiocesium was mainly distributed north of 36.5°N due to the boundary formed by the Kuroshio Extension. The temporal variations of FDNPPA-derived ¹³⁴Cs and ¹³⁷Cs suggested that their environmental half-lives in the study area were 61 d and 63 d in the period of June 2011 to June 2012, respectively.

In this research, we have developed and validated a modified version of the U.S.EPA method 506 using a liquid-liquid extraction method followed by gas-chromatography mass spectrometry analysis to assess the occurrence and spatial and seasonal variation of six phthalates (di(2-ethylhexyl) phthalate-DEHP, dibutyl phthalate-DBP, butyl benzyl phthalate-BBP, diethyl phthalate-DEP, dimethyl phthalate-DMP, and di-n-octyl phthalate-DOP) in surface and tap waters from South Florida, collected during the wet and dry seasons. The most frequently detected phthalate was DEHP, with concentrations up to 1.56 μg/L in surface water. Higher DEHP concentrations were observed in tap water during the wet season, which aligns with the higher temperature during the summer months facilitating leaching from plastic materials. Preliminary ecological and human health risk assessments suggested low hazard risk based on concentrations observed in tap and surface waters, respectively. PAEs could however still constitute a great concern to sensitive marine species, including early stages organisms and coral reefs.

Seasonal distribution of four metals (Cd, Cu, Pb, and Zn) in eight shellfish species collected from the heavily contaminated Cuddalore coast in Tamil Nadu, Southern India, were analyzed. Metal concentrations in all shellfish species were determined using atomic absorption spectrometry. All metals were present in all seasons in most of the species, however, with a few exceptions. Overall, the metal concentration was in the descending order: Zn > Cu > Pb > Cd. Metals might have emerged from both natural and anthropogenic sources as per multivariate statistical analysis. Bioaccumulation factor results showed that cadmium was more bioaccumulated and beyond the threshold limit. Hazard index (HI) values revealed that consuming shellfish from Cuddalore coast can pose hazards to human health, with all HI values beyond threshold limit across all seasons — premonsoon (1.33), monsoon (1.73), postmonsoon (2.55), and summer (2.64). It is evident that consumption of shellfish across all seasons may have adverse health impacts to the people.

This study investigated the structure and function of macrobenthic community in Bohai Bay upon improvement of water quality due to pollution abatement. A total of 166 species were collected in the summer and autumn sampling, with an increase in sensitive species recorded as compared to data from previous studies. While historical variations in species richness indicated signs of improvement in community structure, results of functional diversity indices revealed that the macrobenthic community in Bohai Bay was still in an early stage of recovery. From BIO-ENV analysis, habitat instability may hinder how community responded to water quality improvement. Results of the benthic habitat quality assessment also indicated that the ecological status in most areas of Bohai Bay was classified as good, while a few estuarine regions were categorized in a poor status.

Investigate the growth adaptation law of the Tamarix chinensis root system in response to the groundwater level in a muddy coastal zone. The high groundwater level (0.7–0.9 m), medium groundwater level (1.1–1.3 m) and low groundwater level (1.5–1.7 m) T. chinensis forests on the beaches of the Yellow River Delta were used as the research objects. Full excavation methods were used to excavate root systems with different groundwater levels; then, the aboveground biomass, root biomass, root spatial distribution, root topological structure and fractal characteristics of T. chinensis response characteristics to groundwater level were measured and analysed. The results showed that with the decrease in the groundwater level, the soil water content and soil salt content showed upward trends. At high groundwater levels, T. chinensis reduced root biomass allocation to reduce the damage to roots caused by salinity. At low groundwater levels, T. chinensis strengthened the development of root systems, which greatly enhanced the ability of T. chinensis to balance its water intake. The root biomass at the high groundwater level was 43.06% lower than that at the low groundwater level. The relationship between root and shoot growth of T. chinensis at high groundwater levels and medium groundwater levels indicated allometric growth, and at low groundwater levels, roots and shoots grew uniformly. The root distribution of T. chinensis tended to be shallow at the different groundwater levels, showing the characteristics of a horizontal root type. At high groundwater levels, the root topological structure tended to be dichotomous, and the fractal dimension and fractal abundance values were both large, at 1.31 and 2.77, respectively. The branch complexity increased to achieve spatial expansion and increase plant stability. However, the topological structure of the medium and low groundwater level T. chinensis tended to be herringbone-like, the fractal dimension and fractal abundance values were small, the second branch was limited, and the structure was simple. The topological structure and fractal characteristics of the T. chinensis root system responded to different groundwater levels in a coordinated manner. Based on the differences in the growth and architecture of the T. chinensis root system, the T. chinensis root system has strong phenotypic plasticity to the heterogeneous water-salt habitat of the groundwater-soil system, and the T. chinensis root system shows strong root adaptability to water and salt stress.

This study investigated the year-to-year variability in the occurrence, abundance and sources of oil spills in the Eastern Arabian Sea (EAS) using sentinel-1 imagery and identified the potential oil spills vulnerable zones. The four consecutive year's data acquired from 2017 to 2020 (March–May) reveal three oil spill hot spot zones. The ship-based oil spills were dominant over zone's-1 (off Gujarat) and 3 (off Karnataka and Kerala), and the oil field based over zone-2 (off Maharashtra). The abundance of oil spills was significantly low in zone-1, only 14.30km² (1.2%) during lock-down due to the covid-19 pandemic. Whereas, the year-to-year oil spills over zone's 2 and 3 are not significantly varied (170.29 km² and 195.01 km²), further suggesting the influence of oil exploration and international tanker traffic are in operation during the lock-down. This study further recommends that manual clustering is the best method to study the distribution of unknown oil spills.

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.

Sediments are considered to be important sinks of microplastics, but the enrichment process of microplastics by blue carbon ecosystems is poorly studied. This study analyzed the spatial distribution and temporal changes, assessed the polymer types and morphological characteristics of microplastics in sediments of five ecosystems, i.e. forests, paddy fields, mangroves, saltmarshes and bare beaches on Ximen Island, Yueqing Bay, China. The trapping effect of blue carbon (mangrove and saltmarsh) sediments on microplastic was further explored. Temporal trends in microplastic abundance showed a significant increase over the last 20 years, with the enrichment of microplastics in mangrove and saltmarsh sediments being 1.7 times as high as that in bare beach, exhibiting blue carbon vegetations have strong enrichment effect on microplastics. The dominant color, shape, size, and polymer type of microplastics in sediments were transparent, fibers and fragments, <1 mm, and polyethylene, respectively. Significant differences in the abundance and characteristics of microplastics between intertidal sediments and terrestrial soils reveal that runoff input is the main source of microplastics. This study provided the evidence of blue carbon habitats as traps of microplastics.

This review assesses the leachate quality from waste disposal sites in tropical climate zone. Through this review, data from 228 leachate samples from 145 waste disposal sites from 18 countries in the tropical region were analyzed. The 12 types of sites were considered for the analysis based on the climatic conditions, age, and the operating condition of the site. Tropical rainforest, tropical monsoon, and tropical savanna climates were identified for the climatic zone classification. Age of site was classified as young and old. The operating conditions were classified as engineered landfill and open dump site. Eighteen leachate quality parameters were included in the analysis. Leachate pollution index indicated that young sites from tropical rainforest zone and tropical monsoon zone have higher pollution potential, while the pollution potential in tropical savanna zone did not demonstrate considerable difference in pollution potential in terms of age of the landfill. Considering the operating method of the sites, open dumpsites pose higher pollution potential. Positive correlation could be seen among biological oxygen demand, chemical oxygen demand, total dissolved solids, and total Kjeldahl nitrogen. pH negatively correlated with organic pollutants as well as heavy metals. Analysis of emerging contaminants present in landfill leachate is limited in tropical region; thus, it is recommended to conduct studies on emerging contaminants. Further, the leachate treatment options considered in tropical region are discussed in this review.

Trace elements have the potential to bioaccumulate in marine organisms and to biomagnify towards the upper levels of marine trophic webs, resulting in a range of negative effects on organisms. Elasmobranchs are highly susceptible to bioaccumulation of trace metals, while their consumption by humans is increasing worldwide. Therefore, it is important to monitor the trace metal content in the edible tissues of elasmobranchs. This work reveals the content of 12 trace metals in the edible tissues of 10 elasmobranch species caught in Greek waters. Levels above the permissible limits for Hg and Pb were found in some species, while analysis of the lifetime consumption risk for adults and children using the Target Hazard Quotient (THQ), revealed a high risk for two of the most toxic substances on the priority list for substances, namely As and Hg. These are preliminary results, and further research is required to understand better the issue.