Hiroshi Sakugawa

The increase in industrial activities has raised concerns regarding air quality in urban areas within Malawi. To assess the source apportionment of air quality parameters (AQPs) and noise levels, concentrations of AQPs (CO, TSP, PM _2.5, PM₁₀) and noise levels were monitored at 15 sites in Makata, Limbe, Maselema, Chirimba, and Maone during dry and wet seasons, respectively. Active mobile multi-gas monitors and a Dylos DC1100 PRO Laser Particle Counter (2018 model) were used to monitor AQPs, while Integrated Sound Level Meters were used to measure noise levels. Monitoring and analysis were guided by the World Health Organization (WHO) and Malawi Standards (MS). A Positive Matrix Factorization (PMF) model was used to determine the source apportionment of AQPs, and matrix trajectories analysed air mass movement. In the wet season, the average concentration values of CO, TSP, PM₁₀, and PM_2.5 were 0.49 ± 0.65 mg/m³, 85.03 ± 62.18 µg/m³, 14.65 ± 8.13 µg/m³, and 11.52 ± 7.19 µg/m³, respectively. Dry season average concentration values increased to 1.31 ± 0.81 mg/m³, 99.86± 30.06 µg/m³, 24.35 ± 9.53 µg/m³, and 18.28 ± 7.14 µg/m³. Noise levels remained below public MS and WHO standards (85 dB). Positive correlations between AQPs and noise levels were observed, strengthening from weak in the dry season to moderately strong in the wet season. PMF analysis identified key factors influencing AQP accumulation, emphasizing the need for periodic sampling to monitor seasonal pollution trends, considering potential impacts on public health and environmental sustainability. Further studies should look at factors affecting the dynamics of PMF in Blantyre City.

We assessed the contamination, dynamics, and health risks of the pesticides cyanazine, simetryn, fenarimol, isoprothiolane, diazinon, irgarol, fenitrothion, and diuron in marine samples (seawater, sediments, plankton, fish, and other edible organisms) at various locations in the Seto Inland Sea in Japan in 2016 and 2017. Pesticide concentrations were highest at sampling sites close to the coastline, and mean concentrations in seawater were slightly higher in surface water than in bottom water. All eight pesticides were detected in plankton. Diazinon concentrations (77–387 ng/g dw) were highest in sediments and cyanazine was the most frequently detected pesticide (88%, n = 17) in sediments. Only cyanazine (2.7–41.9 ng/g dw), simetryn (1.0–34.3 ng/g dw), and diazinon (6.3–308.8 ng/g dw) were detected in fish and other edible marine organisms. Based on the calculated bioconcentration factor, the results showed that plankton, fish, and marine animals bioaccumulated pesticides. The highest hazard quotients were calculated for diazinon in red seabream and greenling, indicating a possible risk to consumers. It is, therefore, imperative to promote strict implementation of pollution control, integrated pest management practices, and policy formulation on pesticides. Usage of diazinon must be controlled and monitored to ensure large residues do not reach aquatic ecosystems and marine coastlines.

Polycyclic aromatic hydrocarbons (PAHs) were analyzed to elucidate the distribution, ecological risk, pathways, and fluxes of these pollutants in and around the Seto Inland Sea, an industrialized coastal region of Japan. High molecular weight PAHs (5–6 rings) were primarily found in regions close to the bay estuaries, and their proportions decreased at distances further from the estuaries (offshore areas), where low molecular weight PAHs (2–4 rings) were more ubiquitous. Screening-level risk assessments revealed that the PAHs found in the sediments should have no adverse effects on benthic communities. A mass balance for PAHs in the Seto Inland Sea, calculated based on data collected in the field and published literature findings, showed the PAH flux into the Seto Inland Sea from atmospheric deposition were ca. 6 times higher than that from riverine inflows. Comparison of the amount of the PAH mass flux between the Seto Inland Sea and the sea of the Europe and Asian countries indicated that the Seto Inland Sea is less polluted than the Gulf of Lion, the Mediterranean Sea, and the Bohai Sea, China and more polluted than the Yellow Sea. This paper is the first to determine the fluxes of PAHs in the coastal region of Japan.

This study conducted an integrated approach combining monitoring and risk assessment of pesticides in Kurose River and its catchment area, Japan. Water samples (n = 168) were collected every month for 1 year (March 2016 to February 2017). Pesticides (cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon) were extracted by Sep‐Pack C18 cartridges and analyzed using a reversed‐phase HPLC‐UV system. The pesticides were also determined in non‐target organisms Red algae (Audouinella sp.) and diatoms (Cocconeis placentula) from the river. Based on the residual concentrations, an ecotoxicological risk assessment was conducted using the risk quotient (RQ) index. The human health carcinogenic and non‐carcinogenic risk assessments were evaluated using hazard quotients (HQ). Results showed that cyanazine was the most commonly detected (64%), followed by simetryn (58%), and diazinon (57%) in all the sample sites (n = 12). Except for isoprothiolane, the pesticides were highest in spring followed by summer, autumn and winter. Based on extreme values (ex), non‐acceptable ecotoxicological risk was obtained for diazinon (RQ_ex = 21.317), cyanazine (RQ_ex = 3.129), simetryn (RQ_ex = 8.577) and fenarimol (RQ_ex = 10.855), while that of isoprothiolane (RQ_ex = 0.013) was negligible. Based on the HQ estimates, all the pesticides were below the threshold value of 1, hence pose no significant health risks to humans.Practitioner Points: Pesticides affect non‐target organisms in rivers and other aquatic systems Pesticides were frequently detected in spring and summer and accumulated in red algae and diatom The detected pesticides posed high ecotoxicological and human health risks

Polycyclic aromatic hydrocarbons (PAHs) were analyzed to elucidate the distribution, ecological risk, pathways, and fluxes of these pollutants in and around the Seto Inland Sea, Japan. High molecular weight PAHs (5–6 rings) were primarily found in regions close to the bay estuaries, and their proportions decreased at distances further from the estuaries (offshore areas), where low molecular weight PAHs (2–4 rings) were more ubiquitous. Ecological risk assessments revealed that the PAHs found in the sediments should have no adverse effects on benthic communities, with the exception of fluorene, which was detected in high levels in the sediment from Beppu Bay. A mass balance for PAHs in the Seto Inland Sea, calculated based on data collected in the field and published literature findings, showed the PAH flux into the Seto Inland Sea from atmospheric deposition were ca. 5 times higher than that from riverine inflows. Comparison of the amount of the PAH flux between the Seto Inland Sea and other seas suggested that the Seto Inland Sea is less polluted than the Gulf of Lion and the Bohai Sea, and more polluted than the Yellow Sea.