Analyses Conducted by SPMC's Marine Chemistry Facilities
These basic measurements of the chemical and physical properties of seawater provide information that is relevant to a variety of environmental and ecological processes. For example, measurements of seawater temperature can provide useful information about climate change when they are made over long periods of time. Shorter-term measurements of seawater temperature can also be useful when studying how organisms adapt to daily and seasonal temperature fluctuations in their enviroment. Measurements of salinity and conductivity can provide information about inputs and trajectories of freshwater from rivers into marine waters as well as information that is useful when studying how organisms adapt to changes in the salt content of the water that they live in. Dissolved oxygen measurements can be used to locate areas of low oxygen that occur because of the decay of algal blooms as well as providing information about how marine plants and animals tolerate or adapt to hypoxic conditions. At SPMC, temperature, salinity, dissolved oxygen, and conductivity measurements are made with a YSI 85 meter.
Seawater pH has been a topic of increasing interest due to concerns about ocean acidification, which is predicted to occur as a result of increases in the carbon dioxide content of the atmosphere. Routine analyses of pH at SPMC are conducted with a Symphony pH meter.
Nitrate and nitrite are dissolved forms of nitrogen found in seawater. In the Puget Sound region, the availability of nitrate can limit algal growth, so measurements of nitrate can be important in predicting or explaining rates of algal growth or the presence of algal blooms. MCF conducts measurements of nitrate and nitrite in seawater with an AlpKem autoanalyzer.
Ammonia is another form of dissolved nitrogen that can be important to the growth of phytoplankton and seaweeds. MCF is planning to expand its list of chemical analyses to include measurements of ammonia in the future.
Although nitrogen is the nutrient that most often limits algal growth, there are times and locations where the availability of dissolved phosphorus can be limiting. MCF uses colorometric methods to measure orthophosphate concentrations in seawater.
The availability of dissolved silicate is important to the growth of several types of phytoplankton, especially diatoms, one of the most abundant phytoplankton groups in the Puget Sound region. MCF uses a colorometric method to silicate measure concentrations in seawater.
Chlorophyll a is a photosynthetic pigment that is found in phytoplankton. Measurements of chlorophyll a are good indicators of the overall abundance of phytoplankton in the water. MCF uses a fluorometric method to quantify chlorophyll a.
Measurements of phaeopigments can be used to estimate the abundances of diatoms in marine waters. Phaeopigments are quantified by MCF with fluorometry.
Because nitrogen is often the primary factor that limits the growth of algae and plants, measurements of the concentrations of carbon and nitrogen in their tissues can provide information about nitrogen limitation of primary production over longer times scales than is provided by single measurements of nitrogen in seawater. MCF measures tissue carbon and nitrogen concentrations with an EA 1112 elemental analyzer.
In addition to the analyses routinely conducted by MCF, individual researchers at the Shannon Point Marine Laboratory conduct other types of chemical analyses as part of their research programs. These analyses include measurements of dopamine in marine seaweeds, measurements of sulfur compounds such as dimethylsulfoniopropionate (DMSP) and dimethyl sulfide (DMS) in phytoplankton, invertebrates, and seaweeds, and measurements of algal pigments in phytoplankton. Although training in these analyses is not provided by MCF, the researchers conducting these analyses may be willing to engage in collaborative research on a time-permitting basis.