Application of Soft Data in Nodule Resource Estimation
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https://doi.org/10.1007/s11053-020-09777-2
Original Paper
Application of Soft Data in Nodule Resource Estimation Steinar Løve Ellefmo
1,3
and Thomas Kuhn
2
Received 27 April 2020; accepted 31 October 2020
Minerals and metals are of uttermost importance in our society, and mineral resources on and beneath the deep ocean floor represent a huge potential. Deciding whether mining from the deep ocean floor is financially, environmentally and technologically feasible requires information. Due to great depths and harsh conditions, this information is expensive and time and resource consuming to obtain. It is therefore important to use every piece of data in an optimum way. In this study, data retrieved from images and expert knowledge were used to estimate minimum and maximum nodule abundances at image locations from an area in the Clarion-Clipperton-Zone of the equatorial North East Pacific. From the minimum and maximum values, box cores and the spatial correlation quantified through variogram, a conditional expectation and associated uncertainty were obtained through the Gibbs sampler. The conditional expectation and the uncertainty were used with the assumed certain abundance data from the box cores in a kriging exercise to obtain better informed estimates of the block by block abundance. The quality assessment of the estimations was done based on distance criterion and on kriging quality indicators like the slope of regression and the weight of the mean. From the original image locations, alternative image configurations were tested, and it was shown that such alternatives produce better estimates, without extra costs. Future improvements will focus on improving the estimation of the minimum and the maximum values at image locations. KEY WORDS: Ordinary kriging, Conditional expectation, Gibbs sampler, Variance of measurement error, Resource classification.
INTRODUCTION Society needs minerals. Minerals and metals constitute important ingredients in everything from cars, over toothpaste to mobile phones. To replace petroleum-based energy production with renewable energy and e-mobility requires significant amounts of certain metals such as copper, nickel, cobalt and rare earth elements (REEs) to name a few (Ma˚n1
Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway. 2 Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany. 3 To whom correspondence should be addressed; e-mail: [email protected]
berger and Stenqvist 2018; Teske 2019). Although the remaining metal resources onshore seems to be abundant for, e.g., copper (Singer 2017), the uneven global distribution of minerals and metals as well as the growing ecological pressure on terrestrial deposits call for alternative sources due to high future demand (Elshkaki et al. 2018). The deep sea offers a great potential for mineral resources (Cathles 2011; Hannington et al. 2011; Hannington 2013; Singer 2014; Ellefmo et al. 2019), but there is still a significant amount of uncertainty ass
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