Reactions of the heavy metal cycle to industrial activities in the deep sea: An ecological assessment

Abstract

This article focuses on possible geochemical consequences of potential industrial activities in the deep sea, such as manganese nodule mining, for the heavy metal cycle of the deep sea and possible reactions of the benthic ecosystem. The metal fluxes induced by sediment resuspension are compared with fluvial, atmospheric, and hydrothermal metal fluxes into the ocean. The results of geochemical laboratory experiments and analyses of deep-sea benthic organisms are discussed with respect to their ecological importance in case of a seabed disturbance. A limited short-term increase of heavy metal concentrations in the benthic layer will probably cause only negligible harmful effects on the biota. An essential precondition is that the geochemical milieu remains largely unchanged; especially variations of the redox conditions would result in changes in metal speciation, bioavailability, and toxicity.