Lake Tanganyika shows pcrmancnt thermal stratification with deep-water temperatures that have been stable over the period of observation (since 1939). The lake is anoxic below -150-m depth. In general the nutrients show Redficld behavior save in the deep waters of the northern basin where large excesses of phosphate and ammonia are prcscnt. Bacterial disproportionation of organic material probably plays an important role in producing these excesses. Inorganic dcsorption from fluvial detritus is also a possible source of excess phosphate in deep waters, The oxic-anoxic boundary at -150 m is a sink for all forms of fixed nitrogen. Thus the nutrient budget of the lake probably involves fixation of nitrogen in the surface layer in addition to substantial inputs from rainfall and runoff, with the phosphate supplied by vertical mixing. Because these processes arc in approximate balance under present conditions, the productivity of the lake must be very sensitive to changes in climatic forcing.

A study has been made of carbon-13 and oxygen-18 variations in Greek marbles from the ancient quarry localities of Naxos, Paros, Mount Hymettus, and Mount Pentelikon. Parian, Hymettian, and Pentelic marbles can be clearly distinguished by the isotopic relationships; Naxian marbles fall into two groups characterized by different oxygen-18/oxygen-16 ratios. Ten archeological samples were also analyzed; the isotopic data indicate that the "Theseion" is made of Pentelic marble and a block in the Treasury of Siphnos at Delphi is probably Parian marble.

Mt. Everest (known as Sagarmatha and Qomolangma in Nepal and China, respectively) is an iconic peak sitting within the vulnerable water tower of high-mountain Asia. This issue of One Earth features initial outcomes from the 2019 National Geographic and Rolex Perpetual Planet Everest Expedition, which examined the effects of climate change on the world's highest mountain.

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