Potential of geophagous earthworms in ecofriendly and sustainable biomining of gold from auriferous soils

Abstract

Earthworms are the major contributors of soil invertebrates. Earthworms play a major role in soil amendments, nutrient turnover and participate in the aeration as well as in mixing of various soil horizons. Earthworms are mentioned as one of the Uparasa in Indian Ayurvedic medicine due of its ability to uptake heavy metals. They are soil feeders and hyperaccumulators of heavy metals. There are studies on the bioavailability of Au nanoparticles from soil and biodistribution within earthworms. Goa is situated in the north western part of the metallogenic archean Western Dharwar Craton (WDC) and there are various reports on presence of gold in the WDC. This paper reports how geophagous earthworms can be used in ecofriendly and sustainable biomining of gold from auriferous soils of Goa. Exploration and collection of vermicasts from mining and non-mining areas of Goa was carried out. Detection of gold in the vermicasts samples was done, morphological and typological classification of vermiform gold and fractal analysis of the vermicasts of Goa was carried out. The gold in ppm ranged from 0.66 to 1.77 ppm. We also present the future roadmap of ecofriendly and sustainable biomining of vermiform gold from auriferous soils of Goa.