Work

Particle and carbon export from a restored goldmine in an Amazonian catchment: hydro-sedimentary source tracing

Year: 2026

Type: article

Abstract: Artisanal and small-scale gold mining (ASGM) is prevalent in South America and the Amazon. It involves soil reworking, leading to an increase in downstream river turbidity and ecosystem degradation. In French Guiana, restoration, including landscaping and tree-replanting, is mandatory for legal gold mines, but the fate of post-exploitation sites is poorly characterised. To investigate the extent of particle export originating from a restored gold-mining site, high frequency suspended solid concentrations (SSC) and discharge measurements were performed upstream and downstream of a site in French Guiana. Two flood events were followed with geochemical tracers involving multielemental concentrations and Fourier-transformed infrared spectroscopy (FTIR) data in the particulate and filtered fractions, to unravel the origin of water (overland flow and groundwater), and particles (forest topsoil, mine topsoil, or riverbed sediments) within the watershed. Results show that within the year following restoration, the mining site remains a significant source of particles and carbon to the river, with an excess 100–300 kg km −2 (1.5–2.4 times increase) of particles exported due to the mining site, and specific carbon exports amounting to 9.8 ± 0.6 t C yr −1 km −2 , comparable to exports observed in larger watersheds in the Amazon region. Hydrogeochemical and mineralogical data in the particulate fraction hint towards riverbank erosion and riverbed sediment remobilisation as an important source of suspended particles rather than mining site surface erosion. This underlines the importance of restoring and stabilising the riverbed in the goldmine rehabilitation process.

Source: Journal of Hydrology

DOI: 10.1016/j.jhydrol.2026.135926