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.
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.
Zinc is frequently reacting with inorganic species in water to form zinc species. Thus, the chemical speciation of Zinc in the aquatic environment has become a significant concern nowadays due to its adverse effect on humans and its potential toxicity in the water system. In this study, to investigate the interaction between dissolved zinc and hydro-chemical factors and to estimate the Zn speciation form, samples of river water were collected spatially from the Umeda River mainstream and tributaries in different seasons for one year. The hydrochemistry and dissolved zinc pollution characteristics of the samples were analyzed. Zn speciation was assessed by PHREEQC simulation. The result show that the main form of Zn speciation was Zinc free ion (Zn2+) in all seasons. However, in summer and spring season, the ZnCO3 and ZnOH+ concentration was higher than the other season. These speciation form may be attributed to the activities around the river in different season according to the similarities in downstream and upstream areas by the hierarchical cluster analysis result.
Unlike other potentially toxic metals, zinc (Zn) is indispensable to life but also poses environmental risks to aquatic organisms. Aichi Prefecture has the Japan's fourth-highest discharges of Zn into water bodies. It is likely that the Zn fluxes in Aichi's water bodies originate from industrial wastewater. This study evaluates the spatial-temporal and diel variability of Zn on sunny days during weekdays and weekends in the Umeda River. The most downstream point is considered as the most polluted section according to the monthly survey [dissolved Zn (D-Zn): 0.0046-0.0719 mg L −1 , particulate Zn (P-Zn): 0.42-2.01 mg g −1 ] that varied between seasons (coefficient of variation: 95% for D-Zn; 53% for P-Zn). The total Zn (T-Zn) concentrations on weekdays (0.015-0.043 mg L −1 ) at the most downstream point exhibit much higher concentrations than those during the weekends (undetected-0.032 mg L −1 ). Given the dissolved phase of these Zn levels (77 ± 11%), the Zn are likely discharged by industrial facilities on weekdays. The T-Zn loading on weekdays (56 g km −2 d −1 ) is approximately three times higher than that on weekends. At least 67% of the T-Zn and 70% of the D-Zn fluxes from industrial point sources are potentially discharged on weekdays.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.