Nutrient Decline and Metal Pollution Since the Second Industrial Revolution: The Red Sea

Abstract Reconstructing element concentrations in sediment cores helps identify historical natural or human-induced environmental changes. This study investigates variations in 15 element concentrations in Red Sea (a hot spot for biodiversity) sediment cores over the past five centuries. The findings reveal a significant change in sediment element accumulation rates (EAR) following the Second Industrial Revolution (~1870) and the opening of the Suez Canal. In the North, where industrial activities become prevalent, we observe an increase in the mean EAR of Fe, Cd, V, Zn, Cu, and Cr from 4.56% to 17.6%, with positive slope change rates ranging from 332% (Fe) to 1003% (Cu). Conversely, in the South, we observe a decline in the mean EAR of Mg, total N, total organic C, and Ca from -8.5% to -17.8%, with negative slope change rates ranging from -83% (Ca) to -13980% (Mg). The results reveal the increasing accumulation of trace metals from human activities in recent decades in the North, whereas the South is experiencing a decline in nutrient input from the Indian Ocean associated with ocean warming. These two challenges may be synergistic and have a detrimental effect on the Red Sea ecosystems.