A stringent environmental quality standard for zinc (Zn) has been enacted by regulators because of its toxicity to aquatic life. This study’s objective was to evaluate the variability of Zn concentrations and fluxes in the baseflow and stormflow and to estimate the contribution of Zn from point and non-point sources. By using high-resolution temporal sampling, the suspended solids (SS), iron (Fe), and Zn concentrations were measured in a small agricultural river catchment. Fe, as the natural non-point source, and Zn were evaluated using the end member mixing analysis (EMMA) to identify the source apportionment (point and non-point). The results indicate that in the baseflow, Zn mainly originated from point sources and was possibly discharged by manufacturing industries. By contrast, the non-point sources (diffuse sources) were responsible for extremely high SS, Fe, and Zn levels in the stormflow. In addition, Zn discharge during the stormflow was 93 times higher than that during the baseflow. According to the EMMA, approximately 74% of the Zn was from point sources. River management can be improved if Zn point sources are adequately treated. During a storm event, it is also important to control the particulate Zn released into the river.

Due to the adverse effects of zinc (Zn) on the aquatic organisms, environmental quality standards (EQS) for zinc of 0.03 mg/L in surface water has been enacted in Japan since 2003. However, “zinc elevated sites” persist, including Aichi Prefecture. This study aims to assess the spatial and temporal variability of zinc contamination for 14 months in surface water of the Umeda River, Aichi Prefecture. The water samples were analyzed using Flame Atomic Absorption Spectrometry. The zinc concentrations tended to be higher in a downstream direction. The concentration means of nine sampling stations in surface water in August 2019 to July 2020 varied from 0.011 to 0.031 mg/L. The annual mean concentration value has already exceeded the EQS. Meanwhile, the yearly concentration means of the industrial wastewater were 0.036 to 0.079 mg/L, lower than the National Effluent Standards of 2 mg/L in Japan. All sampling points had relatively high concentrations ranged from 0.021 to 0.062 mg/L in February during the winter season. The reduced precipitation causing low river discharges might consequently elevate the zinc concentrations. The total zinc load at the most downstream section was approximately 0.012 t/km²/year. According to this study, the Umeda River has been affected by anthropogenic activities.

Music concerts have increasingly raised concerns due to their contribution to noise pollution in urban environments. Aim: this study aimed to analyze noise levels and their characteristics during outdoor music concerts in Makassar City, examine the spatial distribution of noise from the source to surrounding areas, and evaluate the effectiveness of vegetation and buildings as noise barriers. Methodology and results: Observations were conducted at 16 sampling points in the Mandala Monument area and nearby urban zones. Noise mapping was carried out using the inverse distance weighting (IDW) method, and statistical analysis was performed with paired t-tests. Results indicate that even without concerts, certain urban locations exceeded the noise standards, suggesting that urbanization alone contributes significantly to noise pollution. During concerts, noise levels surpassed the Indonesian regulatory standards, with concrete structures identified as the most effective noise barriers, reducing noise intensity by up to 17.5 dB. Conclusion, Significance, and Impact Study: The findings emphasize that outdoor music concerts substantially increase environmental noise risks in urban areas. The effectiveness of structural barriers highlights their role in urban noise management. This study underscores the urgency of implementing stricter urban planning and regulatory frameworks for concerts to mitigate environmental noise and safeguard public health.

This study quantified the linkage between the watershed abundance of agricultural mulch film and its accumulation along riverbanks in Hamada River catchment, Japan, by integrating riverbank monitoring, catchment-wide surveys, hydrological connectivity assessment, and delivery ratio estimation. Black film was predominantly associated with red perilla, while silver film was almost exclusively used for tobacco. Riverbank monitoring from 2023 to 2025 showed that mulch film contributed disproportionately more to surface area coverage than to weight density, reflecting its thin, sheet-form geometry. Its accumulation was significantly associated with episodic hydrological connectivity, whereas other macroplastics showed few significant hydrological associations. This study provides quantitative estimate of the delivery ratio of agricultural mulch films from agricultural land to river systems, a linkage rarely quantified in prior studies. Annual delivery ratio of silver film ranged from 0.17% to 0.31%, with the highest value in the year for the lowest watershed abundance, indicating that delivery was not determined solely by abundance. In 2025, the delivery ratios were 0.18% for silver and 0.06% for black film, both below 1% but differing by a factor of three despite black film’s greater watershed abundance. These findings highlight the need for an abundance-based plastic mulch management strategy at the catchment scale.

Conceptual diagram of agriculture as cryptic plastic pollution hotspot, linking mulch sheets, macroplastics on river banks, runoff pathways, microplastics in water and sediment, and leakage bar charts. Macroplastics and microplastics are increasingly being documented in riverine systems, yet their pathways remain poorly understood, especially in agricultural catchments. In this study, macroplastics along riverbanks and microplastics in surface water and sediments of the Hamada River in Toyohashi, Japan, were examined, complemented by a survey of mulch sheet and sewage sludge usage. Sampling and analyses were conducted based on the Japanese Guidelines of Riverine Microplastic Survey and were determined using attenuated total reflectance Fourier transform infrared spectroscopy. The abundance of macroplastics was 2.06 ± 0.56 pieces/m2. Almost half the macroplastics found were mulch sheets with polyethylene of varying colors, such as white, black, transparent, and gray, corresponding to an estimated leakage rate of 0.013% from tobacco mulch sheet applications. Mesoplastics averaged 0.01 ± 0.001 particles/m3 in surface water and 20 ± 15 particles/kg in sediment, while microplastics averaged 0.038 ± 0.02 particles/m3 and 75 ± 87 particles/kg, respectively. Films were the dominant type in water, and coated fertilizers were the major type in sediment. The polymer composition was dominated by polyethylene and polypropylene. The dominance of film-shaped plastics in both macroplastic and microplastic fractions suggests that agriculture is a major source of plastic pollution, which may help to inform mitigation strategies and proper waste management in agricultural catchments.