Young Hydrologic Society

A Streams of Thought contribution by Hayat Nasirova

The deep sea, the largest ecosystem on earth and one of the least explored, is home to high biodiversity and offers an abundance of resources (Ramirez-Llodra et al., 2011).

The Ocean Foundation (https://oceanfdn.org/) defines deep sea mining (DSM) as a commercial industry aimed at mining mineral deposits on the sea floor to extract commercially valuable minerals such as manganese, copper, cobalt, zinc and rare earth elements. Although humans have exploited the oceans for millennia, technological developments now allow the exploitation of fisheries resources, hydrocarbons, and minerals below 2000 m depth (Ramirez-Llodra et al., 2011). The mineral deposits are found in three seafloor habitats: the abyssal plains, seamounts and hydrothermal vents (Gollner et al., 2017). Abyssal plains are large parts of the deep ocean floor covered with deposits of sediment and minerals, also called polymetallic nodules and this is currently the main goal of DSM. With an increasing demand for mineral resources, deep-sea mining brought a critical threshold to the ecosystem (Gollner et al., 2017). This is because the depletion of minerals has irreversible consequences that can lead to the loss of habitats, species, and ecosystem services which are unlikely to recover to their original state (Thompson et al., 2018).

A Streams of Thought contribution by Hayat Nasirova

The Caspian Sea (CS) is the largest lake on Earth. It is located at the intersection of Europe and Asia. It is called “sea” because it has an ocean-type earth layer at the bottom as being a remnant of the Tethys Ocean and has the dimensions of a sea. The water level is variable, currently it is approximately -28 meters below the ocean level.

The current worry of some hydrologists is whether the CS will follow the same fate as the  Aral lake. NASA’s Global Water Monitor, which uses radar altimetry data collected by multiple satellites, shows changes in water levels in the CS since the mid-1990s (Figure 1).