To explore the utility of artificial sweeteners (Acesulfame: ACE; sucralose: SUC; saccharin: SAC; cyclamate: CYC) as molecular markers and to establish a historical benchmark of the water pollution status in the 2010 decade, 272 surface water samples, including river water, sewage, and livestock wastewater, were collected from African (Ghana, Kenya, Mozambique, South Africa), Asian (Vietnam, Indonesia, Thailand, Philippines, Cambodia, Malaysia, India, and Japan) and Middle Eastern (Iran and Lebanon) countries during 2010–2019 and were analyzed for the artificial sweeteners by high performance liquid chromatograph with tandem mass spectrometer coupled with online solid-phase extractor. ACE was most frequently detected (87% of the samples) due to its widespread use and lower detection limit (2 ng/L). SUC was less frequently detected (51%) because of its lower sensitivity and detection limit of 100 ng/L, and less widespread use in some low-income countries, probably due to its higher price. SAC and/or CYC were abundant in surface waters of most countries, despite their biodegradable nature. This was ascribed to intensive usage of SAC and CYC and extensive inputs of untreated sewage to rivers due to limited installation of sewage treatment systems. Concentrations of the sweeteners were higher in urbanized rivers (~1 μg/L to ~100 μg/L) than those in corresponding suburban and rural sites, reflecting spatial patterns of sewage inputs. Furthermore, concentrations of the sweeteners were positively correlated with those of linear alkylbenzenes (LABs) for all countries except Malaysia. These results confirm the utility of artificial sweeteners as indicators of sewage inputs. SAC and CYC could be indicators of untreated sewage inputs. ACE has proved to be the most sensitive and reliable marker to assess inputs of sewage, i.e., both treated and untreated, to surface waters. However, ACE concentrations in secondary effluents and receiving waters in Tokyo decreased two orders of magnitude from 2011 to 2019, while sucralose did not show such a marked decrease. This is probably due to the upgrading of activated sludge treatment, i.e., introducing anaerobic-anoxic-oxic (A2O) treatment and resultant higher removal of ACE. Therefore, the measurement of multiple markers, including SUC, is recommended for long-term monitoring.

There has been little research on the pollution of drifted debris in terrestrial ecosystems in coastal areas compared to research focusing on aquatic environment and aquatic organisms. In this study, two species of terrestrial hermit crabs and three species of coastal plants were collected from a polluted site (Nita) and a control site (Furuzamami) in Zamami Island, Okinawa, and analysed to evaluate element contamination in order to evaluate the risk of drifted debris as a source of trace element pollution in terrestrial ecosystems. In both species of terrestrial hermit crabs, Cd was detected at significantly higher concentrations in both the muscle and hepatopancreas of individuals collected from the polluted site. In addition, Pb, often contained in polyvinyl chloride products along with Cd, had higher concentrations in the hepatopancreas of terrestrial hermit crabs in the contaminated site than in the control site. Among the three coastal plants, Pandanus tectorius was the most sensitive to trace element pollution via drifted debris. In general, plants tended to accumulate elements in accordance with their leachability from plastics. This result suggested that trace elements, leaching from drifted debris to soils, accumulated in the plants. These results indicate that leaching rates from drifted plastics have a greater effect on element accumulation in plants than in terrestrial hermit crabs. The degree of influence of the leaching rate of elements from drifting debris differed between the hermit crabs and plants. In addition, the accumulation of elements that were easily adsorbed by plastics was observed in each species. In the environment, drifted debris is potentially hazardous as a medium of contamination to organisms, as it adsorbs various elements during their transport in the ocean.

Organohalogen compounds (OHCs) are persistent environmental contaminants that can pose health risks to both humans and animals. This study aimed to assess the contamination levels of OHCs in dry and wet pet foods sold in Japan and evaluate their potential health implications for companion animals.

Results indicated that OHCs were widely present in all types of pet foods analyzed, with dry foods generally exhibiting higher contamination levels than wet foods. Polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), and decabromodiphenyl ethane (DBDPE) were detected in varying concentrations across different pet food types. The contamination profiles differed based on the raw materials and country of origin. Estimations of OHC concentrations from raw materials highlighted potential contamination sources beyond ingredient-related contributions, including the manufacturing process.

Moreover, risk assessments were conducted to evaluate the potential health risks posed by OHCs exposure through pet food consumption. While PBDEs, CHLs, and DDTs generally posed low risks, PCBs were found to be of concern, particularly in pet foods containing salmon as a primary ingredient. The results underscored the importance of considering the type of pet food and its raw materials when assessing exposure risks.

Three monitoring methods, including manual monitoring methods based on active and passive samplings and an automatic active monitoring method, for atmospheric mercury (Hg) concentrations are recommended in the guidance on monitoring Hg based on Article 22 of the Minamata Convention on Mercury, which entered into force in 2017. However, among these methods, the dataset obtained by manual monitoring based on active sampling and automatic active monitoring has not yet been verified. Parallel observations using these two methods were conducted in one month for each season from May 2021 to February 2022 at urban and rural sites in Japan. The main objective of this study was to evaluate the comparability of the observations obtained using the two methods. Because the sampling duration of the manual monitoring method based on active sampling using the Japanese monitoring network was 24 h, the data on the daily mean concentrations of atmospheric Hg obtained by both methods were compared, and their consistency was evaluated using t-test, correlation analysis, and Bland–Altman analysis.

The observation values obtained by the two methods were consistent (correlation coefficients=0.99 or higher) in all seasons, despite the large seasonal variation in meteorological conditions, and the unpaired t-test indicated that there were no differences between them in each season. Moreover, the Bland–Altman analysis showed that more than 96% of the data points were found to be within the 95% limit of agreement. Therefore, the manual monitoring method based on active sampling used in this study was in better agreement with the automatic active monitoring method. These results indicate that the data obtained by both methods are comparable. Additionally, manual monitoring based on active sampling can be used to build mercury monitoring networks at a lower cost than automatic active monitoring. Overall, the data obtained by both methods were proven to be beneficial for the effectiveness evaluation of the Minamata Convention.

The Karnaphuli River in Bangladesh, a lifeline for socio-economic activities, plays a crucial role by providing a considerable water supply. However, the aquatic environment is under threat from contamination originating from several sources such as industrial wastewater discharge, maritime operations, wastages from garments and leather industries, fertilizers industries, and the discharge of urban runoff. This study revealed the total petroleum hydrocarbon contamination of the Karnaphuli River. This study delves into the total petroleum hydrocarbon concentrations at several key points along the Karnaphuli River. Near the Amanat Shah Bridge, the total petroleum hydrocarbon level is at 29.70 mg/L, whereas it spikes to 84.67 mg/L in Chaktai Khal, indicating substantial variability across different locations. Mahesh Khal registers a total petroleum hydrocarbon concentration of 52.07 mg/L, followed by 31.09 mg/L in Sadar Ghat, 70.04 mg/L in Khal No 10, and 31.87 mg/L in the KAFCO outfall. These findings illustrate the pervasive nature of total petroleum hydrocarbon contamination throughout the river, thereby posing a grave threat to its ecological integrity and the well-being of communities reliant on it. Comparative analysis with a previous study spanning an 18-year interval unveils a decline in total petroleum hydrocarbon concentrations, hinting at potential improvement in environmental conditions. Although this trend offers a glimmer of hope, it underscores the persistent need for vigilant monitoring and concerted efforts to curtail pollution sources. By elucidating the evolving landscape of total petroleum hydrocarbon contamination in the Karnaphuli River, this study furnishes invaluable insights into its environmental implications and paves a way for informed decision-making in environmental management.