Physical, Chemical, and Geological Changes of Marine Environment Caused by the Benthic Impact Experiment at the IOM BIE Site

摘要

In order to predict potential effects of mining of polymetallic nodules, Interoceanmetal Joint Organization (IOM) carried out, in 1995, a Benthic Impact Experiment (IOM BIE) in its pioneer area within the Clarion-Clipperton Fracture Zone. The IOM BIE study involved pre-disturbance (baseline), disturbance and post-disturbance stages as well as subsequent monitoring sampling in 1997. Comparison of data on physical and chemical characteristics of bottom sediment, near-bottom and pore water collected before and after experiment showed alterations in those characteristics. Contents of nutrients (silicates, nitrates, nitrites, and phosphates) and heavy metals (Cu, Zn, Pb, Cd) as well as the mineralogicai and grain size composition of the discharged sediments were determined on material collected by sediment traps, water bottles, and a multiple corer. Preliminary data on characteristics of the disturbed and resettled sediment layer obtained during the 1997 monitoring cruise are presented and discussed.