• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Ross Sea; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.603.6519; http://www.aslo.org/lomethods/free/2004/0091.pdf

We needed to measure nutrient concentrations in a contin-uous stream of seawater delivered to a shipboard laboratory from a towed undulating vehicle (the Lamont Pumping Sea-Soar [LPS]; Hales and Takahashi 2002) at rates faster than stan-dard flow-injection analysis (FIA) systems could achieve dur-ing a field expedition in the Ross Sea, Antarctica. To this end, we modified a Lachat QuikChem 8000 autoanalyzer system to greatly increase its sample throughput. Several minor modifi-cations were important in achieving this goal; the most important of these was the development of a new Cd column for the reduction of nitrate to nitrite. Oceanographic background—Nitrate, phosphate, and silicate in seawater are the most abundant of the nutrients thought to limit phytoplankton growth in many parts of the oceans. The availability of micronutrients, such as iron, and the presence of grazers in the planktonic community may also be impor-tant factors regulating productivity. There are still large areas of the ocean, however, where the supply of these macronutri-ents is the key factor in determining the timing and magni-tude of phytoplankton blooms. Another important factor shaping the distribution and mag-nitude of plankton biomass and growth rate is physical forcing on horizontal scales of 10 to 100 km (the mesoscale). Satellite imagery shows significant and coincident variability in surface ocean properties such as temperature and chlorophyll content on these length scales. The development of towed undulating vehicles has led to great advances in high-speed, high-spatial