Preliminary results of the 2011 KODOS cruise in the NE Pacific: Part II. Environmental studies in the Korea Licensed Mn-nodule field

Abstract

In the 2011 KODOS cruise exploration, the aims of environmental studies were to obtain chemical, biological and sedimentaolgical properties of water columns and bottom sediments as background data for environmental assessment. To characterize water columns, depth-dependent water samples and basic physico-chemical information were acquired at six stations within the Korea licensed Mn-nodule field. In addition, sediment core samples were collected at five stations to analyze the distribution of benthic organisms including bacteria and meo- and macro-benthos in sediments. Finally, mooring systems composed of sediment traps and recording current meters (RCM) were recovered from two stations that were deployed in August 2010. We redeployed these two moorings and deployed two additional systems (total four stations) to identify time-series variations in sediment flux and current flow for a one year period. Beyond the onboard limitation of analytic instruments, several intrinsic features expanding to suspended microorganism and sea water chemical components were identified. In particular, biomass within the top water layer dramatically decreased according to the increase of water depth. This feature is well matched with vertical distribution patterns of organic particles. Fluorocene data showed peak values at ~60 - 120 m water depths in the study area. Dissolved oxygen content showed positive