Water Chemistry and Nutrient Dynamics
What do you see when you think of a beautiful, healthy stream? Your picture probably does not include trash, muddy water, or the smell of a latrine. But looks can sometimes be deceiving and just looking may not tell the whole picture. Sometimes we need a different perspective with very definite standards to really “see” the health and subsequent beauty of a stream. All living things are dependent on water, with fresh water streams providing a major habitat. What do we mean by “stream health”? Generally, we mean the ability of the stream to maintain life (both internally and externally). How do we quantify it? We still use as standards for comparison the historical reports of John Smith and the present day ability of Bernie Fowler to see his toes. However, technology provides us with ever increasing capabilities to measure and quantify the chemical and physical properties of our streams.
The Fall 2009 Marsh Notes reported on Andreas Moshogianis’ intern studies in establishing physical baseline information for each of the Jug Bay stream watersheds. Following this and similar studies of the surrounding environs of the Sanctuary in 2009 (Marsh Notes Winter 2009/2010) a new focus was directed toward research and education about the land practices impacting the three watersheds at Jug Bay: Galloway Creek, Two Run, and Pindell Branches. Since 1987 volunteers at Jug Bay have conducted a bi-monthly study of the Patuxent River and Two Run, measuring dissolved oxygen, water temperature, degrees of acidity, salinity, concentration of suspended particles, and the presence of chemical compounds (nitrates, phosphates, and ammonia) as well as the conductivity of the water. With this new emphasis in mind, the Volunteer Water Chemistry program regrouped in January 2010 to focus on these three streams. The new program included the same measurements as the earlier study, but emphasis was shifted from the River to two sites at each of the three contributing streams. This effort was aided by new instrumentation funded by CBNERR and is currently undergoing an ongoing trial and error study by staff and volunteers to establish new standards and protocol. The following parameters are currently being measured in the three streams.
- Dissolved oxygen (DO) - Dissolved oxygen analysis measures the amount of oxygen (O2) dissolved in the water. Oxygen is a necessary element to nearly every form of life. As dissolved oxygen levels in water drop below 5.0 milligrams per liter (mg/l), aquatic life is put under stress; the lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills.
- Acidity (pH) - The degree of acidity not only limits life within the stream, but also affects those animals who need streams for everything from drinking to breeding to a food source. A pH of 6.5 to 8.2 is optimal for most organisms.
- Turbidity, or cloudiness in water, is caused by suspended materials that scatter light passing through the water. The water chemistry program uses a turbidity tube which measures the depth at which one can see the water. More precise instrumentation for measuring total suspended solids (TSS) has been added.
- Temperature -Temperature is one factor in determining which species may or may not be present. Temperature affects the feeding, reproduction, and metabolism of aquatic animals. Thermal pollution (water running off hot roads and roofs) is a growing threat to species of cold-water streams. Temperature can also be used as a measure of standard for differences in other parameters.
- Salinity - By definition, streams are not the place for salinity-loving creatures. Increased salinity due to erosion or runoff can change the basic nature of a freshwater stream.
- Chemical compounds - The concentrations of nitrates, phosphates, and ammonia determine the nutrient level of the stream.
- Nitrogen/ Nitrate (NO2+3) is essential for plant growth, but the presence of excessive amounts in water supplies presents a major pollution problem. Nitrogen compounds may enter water from agricultural fertilizers, human sewage, industrial wastes, and livestock wastes. Nitrate level should be less than 0.5 mg/l
- Phosphates (PO4) are naturally occurring. However when found in excess they can accelerate the growth of algae and aquatic plants, causing eutrophication. Phosphate levels should be less than 0.05 mg/l.
- Ammonia (NH4) is found in fertilizers. It is also used in refrigeration. As a decomposition product of urea and protein, it is found in wastewater. Toxic levels of NH4 are pH- and temperature-dependent. Ammonia concentrations should be less than 0.05 mg/l.
- Conductivity is a measure of the ability of water to pass an electrical current. Conductivity in water is affected by the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, and phosphate anions (ions that carry a negative charge) or sodium, magnesium, calcium, iron, and aluminum cations (ions that carry a positive charge). The basic conductivity measurement unit is the mho or siemens. Conductivity becomes critical only when studying other indicators of water quality, and is not in and of itself a major indicator.
Two other volunteer programs complement the Watershed Stream Study. First is the quarterly study of macro-invertebrates. This study has focused on the three streams of Jug Bay since November 2009. A stream can be judged by the macro-invertebrate company found within it (Index of Biotic Integrity). These bottom-dwelling creatures differ in their sensitivity to water pollution. Thus macro-invertebrate studies may provide a broader picture of the health of a stream than is seen in just a single water chemistry sample. Second is the fish survey, which is also conducted on a seasonal basis and provides a picture of the health of the fish and variety of species found in our streams. Together the three programs provide a broad picture of the health of the three streams of Jug Bay.
Over time we hope the Watershed Stream Study will serve to document the impacts of developmental growth and global warming on our streams, the impact of our streams on the continued existence or loss of species, and most important, will reflect positive changes to the environs that influence these three streams.
Water Chemistry surveys are conducted by trained volunteers on the third weekend of each month throughout the year. Individuals interested in participating in the program are encouraged to contact Volunteer Coordinator Lindsay Hollister. Background knowledge in water chemistry is not necessary, and ongoing training is provided. Click for procedures manual.
