Chapter I Intro & Objectives - SPREP

PHOENIX ISLANDS PROTECTED AREA MANAGEMENT PLAN
Chapter III. Background, 1. Physical Setting of the Islands
Draft 1 March 2007
The highest manganese nodule abundance was at depths between 5,100 to 5,400 m (Cronan
et al 1991; 5,000 to 5,600 m according to Cronan and Hodkinson 1991; 5,200 to 5,300 m
according to Kinoshita and Tiffin 1993). Kinoshita and Tiffin (1993) estimated that there
were about 571 million tonnes (630 million tons) of manganese nodules in the Phoenix Island
EEZ. More than 272 million tonnes (300 million tons) of nodules may exist in the southeast
part of the Phoenix Islands EEZ.
The highest Ni and Cu concentrations were also at this depth range (Cronan et al 1991 and
Cronan and Hodkinson 1991; see Figure III-1.20). The total amount of Ni in nodules within
the EEZ around the Phoenix Islands was about 11.8 million tonnes (see also Cronan and
Hodkinson 1989 and 1991) According to Kinoshita and Tiffin (1993), the manganese nodule
nickel content needed to be more than 2.67 percent for mining to be cost effective. Phoenix
Islands manganese nodules had an average of 1.35 percent nickel content. Therefore these
nodules (and nodules from all of Kiribati’s EEZs) are of low grade and have no economic
value for commercial harvest in the foreseeable future.
Figure III-1.20. Metal quantity distribution in the EEZ around the Phoenix Islands
(Source: Cronan et al 1991 and Cronan and Hodkinson 1989 and 1991).
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