地理漫步·世界地理英语30篇（1）

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里海到底是湖还是海

The Caspian Sea is Earth’s largest inland body of water, covering 371,000 square kilometers but lacking oceanic connection.
Its salinity averages 1.2%, one-third that of seawater, varying from fresh near Volga inflows to brackish in southern basins.
Tectonic origin distinguishes it from lakes—it sits in a remnant oceanic basin formed by the collision of Arabian and Eurasian plates.
Unlike true lakes, it has marine species like sturgeon and endemic plankton adapted to fluctuating salinity and pressure gradients.
Sea-level changes—up to three meters since the 1970s—reflect climate-driven evaporation and altered river inputs from the Volga and Ural.
Oil and gas platforms operate offshore using marine drilling standards, though jurisdiction falls under littoral state treaties rather than UNCLOS.
Sediment cores reveal ancient marine fossils, confirming its Pliocene connection to the Paratethys Sea before isolation.
Its stratified water column features oxygen-rich surface layers and anoxic deep basins over 1,000 meters deep.
Coastal management requires transnational coordination because shoreline erosion in Turkmenistan affects sediment supply to Kazakh deltas.
Geographers classify it as a 'sea' functionally due to size, hydrodynamics, and biogeography—even if legally defined as a lake by some states.