Pollution Characteristics and Decline in Seawater Quality with Rapid Change in Land Use: Case Study of Bima Bay, East Nusa Tenggara, Indonesia

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Document Type : Original Research Paper

Authors

1 Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung,Jl. Ganesha 10, Bandung, 40132, Indonesia

2 Faculty of Earth Science and Technology, Institut Teknologi Bandung,Jl. Ganesha 10, Bandung, 40132, Indonesia

3 Environmental Engineering Study Program, Faculty of Engineering, Universitas Singaberbangsa Karawang, Karawang, 41361, Indonesia

4 Department of Cultural Anthropology and Development Studies, Faculty of Social Science, Radboud University

10.22059/poll.2025.397309.2991

Abstract

Increased anthropogenic activity in coastal areas has led to a significant decline in marine ecosystem quality, particularly due to the influx of nutrient-rich waste that triggers eutrophication. This study highlights a case of extreme pollution in Bima Bay, West Nusa Tenggara, marked by the appearance of massive brown sea foam in April 2022, covering an area of over 10 hectares. The research was conducted through water quality analysis, acute toxicity testing (LC50), microalgae identification, and satellite image interpretation. Results showed BOD concentrations of 20.8 mg/L, oil and grease at 28.5 mg/L, orthophosphate at 0.037 mg/L, and NO₃-N up to 1.194 mg/L, all exceeding the quality standards set by PP No. 22 of 2021. Toxicity testing yielded an LC50-96 hour value as low as 0.081%, categorized as highly toxic. Microalgae identification revealed a dominance of the Diatom group, such as Nitzschia sp., Navicula sp., and Surirella sp., which thrived due to high nutrient content and favorable water conditions (pH 6.92 - 7.70, high light intensity). Analysis of Sentinel-2 and Landsat 8/9 imagery showed the appearance of foam beginning on April 24 and its disappearance after May 4, 2022. This pollution is closely related to massive land use changes in the upstream area for corn farming expansion, poor domestic sanitation systems, and the semi-enclosed geographical position of Bima Bay, which hinders seawater mixing and accelerates pollutant accumulation. These findings highlight the importance of pollution mitigation based on spatial planning and integrated waste management in tropical coastal areas.

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Pollution

Articles in Press, Accepted Manuscript
Available Online from 21 December 2025

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