9 Jun 2011

Lake Sediments

From Our Changing World, 9:20 pm on 9 June 2011

lake sediments

Chris Hendy with a sediment core from Lake Ngapouri (image: A. Ballance)

The lakes of the Taupo Volcanic Zone are very deep lakes, and much of the very fine silica-rich sediments that accumulate on the lake floors at rates of up to a centimetre a year are derived from summer diatom blooms. Many of these lakes are now impacted by eutrophication, caused by high nitrogen run-off from surrounding farms and forestry blocks. Chris Hendy is an environmental geochemist at Waikato University. He is interested in the chemical processes that take place in pore water within lake sediments, and in the benthic boundary layer – the layer of water sitting directly above the sediments. He explains to Alison Ballance how his research has recently identified a new process of denitrification, able to operate in anaerobic conditions.