Differential effects of gallium and indium addition on metal bioavailability and toxicity in paddy soils: Insights from a soil–water–fish exposure system
Journal
Environmental Pollution
Journal Volume
395
Start Page
127733
ISSN
0269-7491
Date Issued
2026-04
Author(s)
Abstract
Gallium (Ga) and indium (In) are critical metals widely used in semiconductor and optoelectronic industries, where their compounds are indispensable to modern electronic devices. However, improper disposal and industrial effluents have led to their emergence as environmental contaminants, particularly in agricultural systems such as paddy fields. Their environmental fate, ecological toxicity, and potential risks to food safety remain poorly understood in these agroecosystems. In this study, a static soil–water–fish exposure system was developed using juvenile rice fish, medaka (Oryzias latipes), as a model organism to investigate the bioavailability and toxic effects of Ga and In in two contrasting paddy soils: acidic, aluminum (Al)-rich Pingzhen (Pc) soil and neutral, low-Al Sangkang (Su) soil. Sequential and KCl extractions revealed that exchangeable Al in Pc soil increased markedly with rising Ga or In concentrations. Soil pH strongly influenced metal mobility and bioavailability—Su soil released more soluble Ga, while Pc soil released more soluble In, with Ga notably enhancing Al mobilization from soil to water phases. Medaka exposed to highly contaminated Pc soils (>1 mmol/kg Ga or >4 mmol/kg In) exhibited significant mortality, likely due to Al displacement and release. In Su soils, no significant mortality was observed, but exposed fish accumulated Ga or In in a dose-dependent manner, resulting in sublethal effects such as growth inhibition and altered swimming behavior even at lower exposure levels. These findings demonstrate that Ga and In contamination in paddy soils can disrupt soil–water chemical equilibria, increase Al release, and induce both lethal and sublethal toxic effects in rice fish. The soil–water–fish exposure system established provides an effective framework for assessing the agroecological risks of emerging high-tech-related metals. It underscores the need for environmental monitoring and soil quality guidelines to ensure sustainable rice production and food safety.
Subjects
Aluminum (Al)
Ecotoxicity
Emerging contaminants
Gallium (Ga)
Indium (In)
Medaka (Oryzias latipes)
Paddy soil
Publisher
Elsevier BV
Description
Article number 127733
Type
journal article