Drs Emma Gagen and Laura Sonter will give presentations on different aspects of this topic.

Biogeochemical processes in canga ecosystems

The protracted weathering of banded iron formations results in giant supergene iron ore deposits. An indurated iron duricrust known as canga covers these lateritic profiles making it extremely resistant to erosion and protecting the friable ore underneath. Canga is the ultimate weathering product of BIF and is mostly composed of detrital BIF and iron ore, cemented together by goethite. Canga forms the surface layer in these areas and underpins unique plant ecosystems. Effective post-mining rehabilitation strategies for tropical iron ore areas will ideally involve the re-formation of canga.
Geochemical evidence suggests that biogeochemical processes have played an important role in the cycling of iron in canga in the past and that these processes are active in the present day. Enhancing biogeochemical cycling of iron in canga is an ideal platform for re-formation of canga and thus the accelerated remediation of iron ore sites. In this seminar, I will give an overview of current research into iron cycling in canga ecosystems and using iron reducing microbial consortia to promote canga re-formation in the lab and in a field-scale system.

Co-authors: Anat Paz, Alan Levett, Guilherme Oliveira, Gene Tyson, Gordon Southam, Paulo Vasconcelos

Emma is a postdoctoral research fellow in geomicrobiology, in the School of Earth and Environmental Sciences, University of Queensland. Her research focuses on the role microorganisms play in iron cycling in geologic systems. Prior to this, she was at the University of Regensburg, Germany, investigating microorganisms in the deep biosphere (below the seafloor). Before that her PhD research at the University of Queensland was in gut microbial ecology and reducing methane emissions from ruminants. Emma’s research interests extend to all areas of environmental microbiology and she is fascinated by the role microorganisms play in geochemical processes.

Mining, deforestation and conservation opportunities in Brazil

Mining poses significant risks to tropical forests worldwide. However, the full extent of these impacts is rarely understood, let alone captured in environmental impact assessments or mitigation activities. This presentation will illustrate some of the causes and consequences of mining-induced deforestation in Brazil – a country where mining is vital to the national economy but forest conservation is a globally-important goal. Specifically, I will show that (1) mining causes extensive deforestation both within mining leases and up to 70 km beyond lease boundaries; (2) these impacts can have disproportionately large consequences for already threatened ecosystems; and (3) some specific impacts (e.g. deforestation to produce charcoal for iron and steel-making) are also major sources of greenhouse gas emissions. I will conclude by discussing management opportunities, such as biodiversity offsetting policies, to mitigate deforestation and achieve global conservation goals.

Laura Sonter is an ARC DECRA Research Fellow at the School of Earth and Environmental Sciences. Her research seeks to understand where, when and how to manage landscapes for the benefit nature and people. She uses land use change models, coupled with remote sensing and GIS datasets, to predict how development projects (e.g. mines, dams, roads) and conservation activities will impact biodiversity and ecosystem services.


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