Socioeconomic cost of dredge boat gold mining in the Tapajós basin, eastern Amazon

Abstract

With the rapid expansion of artisanal small-scale gold mining (ASGM) in the Brazilian Amazon, an increasing number of studies have attempted to estimate the impacts and socio-environmental costs of ASGM using economic valuation methods. However, most studies focused on alluvial gold mining and few examined dredge boat mining, leading to an under-estimation of the overall impact of ASGM in some regions. The objective of the present study was to develop a methodology for assessing the socio-environmental costs of dredge boat mining in the Tapajós watershed. We developed a method linking the type of gold mining, type of pump, motor power required, time spent in exploration, and mercury use with the average socioeconomic cost. We identified 13 boats in the Tapajós basin in 2020 using satellite images. The total socioeconomic cost of dredge boat mining was US $6.4 million in 2020 (i.e., US $142,556 per kilogram of gold or US $588,887 per ferry). The estimated dredging impact cost may reach US $14.7 million for an optimistic scenario, which would reach US $443.9 million when considering accumulated impact over 30 years. These findings can contribute to a more accurate economic valuation of illegal dredge boat mining, providing valuable information for estimating compensation fines and planning law enforcement investments to prevent illegal ASGM.