Magnetic responses for heavy metal pollution recorded by the sediments from Bohai Sea, Eastern China

The Bohai Sea is facing multidirectional pressure from economic development and pollutant emissions. Magnetic minerals and heavy metal concentrations in the sediments of core M5 from the Bohai Sea were performed. The results of concentration -related magnetic parameters, heavy metal contents, and PLI (Tomlinson pollution load index) illustrate there are essential linkages of the sources, migration, and deposition. The predominant magnetic mineral was magnetite. Based on the chronological data from 210 Pb and 137 Cs activities, the increasing magnetic parameters and heavy metal concentrations at a depth of 81 cm were dated to 1950 CE, which corresponded to the establishment of the People's Republic of China; the decrease at depths of 37-45 cm and 16-18 cm may be related to the decline in steel production in 1960 CE and the Tangshan earthquake in 1978 CE, respectively. This study enriches relevant theories of environmental magnetism via the ecological and environmental protection of the coastal zones.