To help you understand water quality and how it is measured, you will be collecting and analyzing water samples from several areas surrounding LUMCON. We will provide you with the tools needed to collect your samples and to measure several water quality parameters. Once you are finished, you will enter your data into a database located on the internet. This will allow you to access your data (and that of other students) all year long to see how water quality changes with the seasons.
The temperature of a given body of water is determined by the local climate (air temperature, solar radiation), by the volume of water, and by other processes that can add heat (e.g. industry) to the system. As marine scientists we measure temperature because it is a key factor that determines the rate of biological and chemical reactions. For example, many organisms are adapted to live within a certain range of temperatures. If the temperature varies outside of this range for prolonged periods, then certain organisms may not survive. We will be using a simple glass thermometer to measure water temperature in our study area.
LUMCON is situated within the Barataria-Terrebonne Estuary complex, which is the interface between freshwater flowing from northern uplands and the salty Gulf of Mexico to the south. The amount of salt dissolved in the water controls which types of organisms can live in the estuary, and also affects our ability to use certain waters for drinking and industry. You will be using a refractometer to measure salinity.
With some exceptions, estuarine plants and animals require oxygen to survive. Access to plentiful oxygen is usually not a factor on land where oxygen concentration in air does not change from about 21%. However, oxygen concentration in aquatic habitats varies in space and time. For example, cold water can hold more dissolved oxygen than warm water. Areas with plentiful plant life may have higher concentrations of oxygen because of photosynthesis. However, under some conditions too many plants can lead to low oxygen conditions (hypoxia) as the plants die and decompose. We will be using a technique called a Winkler titration to measure the concentration of dissolved oxygen in our study sites.
pH is a measure of the concentration of hydrogen ions in a solution. Measured on a scale from 0 to 14, pH varies due to variables including temperature, dissolved gases, and pollution. Marine scientists use pH as an indicator of water quality. Most marine organisms can tolerate only a narrow range of pH and depend on the natural buffering system of saltwater to maintain pH readings between 7.5 and 8.4. Handheld portable probes makes measuring pH in the field easy and accurate.