Grant: Research Tools and Instruments - Category 1 (<$150,000)

Distributions of biological activity in the world's oceans over a range of time and space scales are controlled, in large part, by the flux of nutrients to the surface waters. These nutrients (largely nitrate, phosphate, silicate, reduced nitrogen forms, and iron) support the primary formation of organic matter by the phytoplankton, which in turn form the base of the entire marine food web. The rate at which these nutrients are supplied to the upper ocean therefore fundamentally constrains the rate of biological production. Under an assumption of steady-state, the net supply of inorganic nutrients is balanced by losses of organic matter, in either dissolved or particulate form. This export is referred to as "new production"; it results in a redistribution of carbon between the surface and deep ocean, and in a complex fashion, can also influence the exchange of carbon between atmosphere and ocean. The rate of nutrient supply therefore has climate implications. As well, in the coastal region, abundant supply of nutrients from terrestrial sources can result in what is termed eutrophication. This is manifested in an overabundance of algae and a depletion of oxygen as a consequence of this nutrient input; increasingly often, these algae are toxic and the accumulation of toxins in shellfish is a human health hazard. For the reasons above, the accurate and precise measurement of the concentration of inorganic  nutrients in seawater is fundamental to a broad cross-section of oceanographic study.      We request funds to purchase an automated nutrient analyzer which can meet these objectives. The device takes a flow-segmented  approach,and routinely measures the concentrations of nitrate, silicate,phosphate and ammonium. The request is to replace a unit that we currently have which is >30 years old (older than all of our graduate students, techs, and pdf's!), and which no longer functions. The result will be a large step in our ability to handle the large number of samples that are currently being taken in our studies of the open ocean, coastal oceans on a global basis, and   intensive studies of the physical and biological dynamics of Canadian coastal embayments.