Circular impacts of hexavalent chromium pollution on the Opak River, Yogyakarta, Indonesia

Uncontrolled wastewater discharge containing hexavalent chromium Cr(VI) from tannery industries in Piyungan Industrial Area (PIA) in Yogyakarta, Indonesia, potentially disrupts ecological and societal elements downstream of the Opak River. We collected samples from the wastewater discharge point of several PIA connected sites and a control location. Samples consisted of river water and solid samples (sediment, aquatic plant, and fish). We also examined fish and rice samples that were dependent on the river ecosystem. Atomic absorption spectrophotometry was used to determine the Cr(VI) levels of the samples. To estimate potential economic loss from fish farming, current fish production and market price data were considered. No significant differences in Cr(VI) concentration between the examined sites and the control site (p<0.05) were found. The average Cr(VI) concentration in river water samples ranged from 0.117-0.397 mg/l, exceeding the required local standard of 0.05 mg/l. Increased distance did not result in lower Cr(VI) concentration in water and solid samples, except in rice grain. The potential economic loss of income is estimated at EUR 103 thousand/year. Our findings presented that persistent and intensifying Cr(VI) pollution potentially leads to a further decline in river ecosystem services, a deterioration in food production standards, and economic loss. Considering the wide distribution of the impact of chromium pollution, the management of and the local government immediately operated a communal wastewater treatment plant, increased supervision, and assistance to business actors to make efficient use of chromium and implemented a recycling process. To improve the decline in river water quality, river remediation, and restoration can be carried out by utilizing aquatic macrophytes such as water hyacinth (Eichhornia crassipes) or by using a wetland system. Thus, cases of chromium pollution can be reduced, and the quality of river water can meet the requirements as a source of water for agriculture and fisheries. © 2024, BIOFLUX SRL. All rights reserved.