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IMPLICATION OF CLIMTE CHANGE ON IOB LIFE

In open oceans systems that are full of dissolved iron, the IOB is ubiquitously and influences significantely the iron cycle. Nowadays this biogechemical cycle is undergoing major modifications, due to pollution and climate change. Infact the normal distribution of this metal in the ocean could be affected by the global warming, the ocean water hypoxia and acidification, and the shifting of ocean currents.

These are all consequences of the substantial increase in CO2 emissions into the atmosphere from anthropogenic sources. Infact, nowadays the carbon dioxide concentration in the atmosphere is 380 ppm ( 80 ppm more than 20 million years ago). About a quarter of the total CO2 emitted in the atmosphere enters the oceans (2.2 pg C year–1) where, reacting with sea water, it produces bicarbonate causing, consequently, the decrease of carbonate of approximately 30 μmol kg–1, and an increase in acidity of 0.1 pH units.

Furthermore, the temperature of the oceans has increased by almost a degree (0.74 ° C to be precise) causing the melting of big quantities of glaciers with a consequent sea level rise and the lowering of O2 solubility by inhibiting the oxygen exchange between surface waters, where the O2 is very abundant, and hypoxic deep waters.

All these changes in the marine parameters of temperature, acidity and oxygenation that obviously impact on Iron biogeochemical cycle and therefore on IOB could have several and critical implications. For example hypoxic and acid conditions could improve primary productivity in the superficial and costal waters because them could lead to increase the availability of ferrous iron Fe(II) promoting microbial iron oxidation. But, at the same time, that could also perturb the sediments cascade in deep water and cause the death of benthonic animals. Moreover is very important to consider that iron and phosphate cycles are strictly interconnected and balanced, so that a small change in the first could have substantial consequences on the second.