Environmental work carried out by KORDI

Abstract

To access the environmental impact by the deep-sea mining activity through the environmental baseline study in Clarion-Clipperton Fracture Zone, the environmental baseline studies were carried out from 1998 to 2010. The study area is covered from the equator to 17 °N, and from 128 °W to 136 °W, including the Korean claim area. From 1998 to 2005, the environmental surveys carried out a wide scale including our claim area. After then, the surveys have been carried out only in our claim area until now. We investigated the distribution and the natural variability of environmental parameters including 5 categories such as physical, chemical, biological, geological, bioturbation and sedimentation which was proposed by ISA environmental guideline (ISBA/7/LTC/1/Rev.1**). The study area is characterized by 3 major surface currents : the south equatorial current (SEC), North equatorial counter current (NECC), and North equatorial current (NEC). Surface water convergence occurred at the boundary of the westward flowing SEC and eastward flowing NECC, and divergence occurred at the boundary of the NECC and westward NEC. The range of NECC was varied from 2 °N to over 4 °N. The sea surface temperature was varied from 26.74 to 28.65℃(average 27.95℃) at a long term monitoring station (KOMO: 10.5°N, 131.33°W) during 15 years (1995 - 2009). The chemical parameters of surface water show typical ocean characteristics with sustaining constant component ratios. The depth of thermocline was annually varied with a few tens of meters. The spatial and vertical distribution of inorganic nutrients and organic matter in surface water was significantly affected by the physical features.Biomass and productivity of pelagic ecosystem in study area show the latitudinal gradient with decrement from equator to higher latitudes. The distribution of benthic fauna also shows the tendency to decrease biomass in the higher latitudes. There is also longitudinal variations of biological factors