Water Quality

Water Quality is a Division B event running in 2012-2013, which test students' ability to identify aquatic organisms and understanding of the indicators of water quality. Topics that may be included in the testing are aquatic ecology, the water cycle, nutrient cycling, aquatic chemistry, potable water treatment, waste water treatment, aquatic food chains and webs, community interactions, population dynamics, watershed resource management issues, sedimentation pollution, and harmful species.

A comprehensive list of organisms that must be able to be identified are located here.

The Basics
Water quality includes the physical, chemical and biological characteristics of water. In countries around the world, especially in the U.S., standards are set to determine whether water is potable, or safe to drink, under the direction of the EPA.

The Water Cycle
For more information on the Hydrologic Cycle (water cycle), please see the Hydrologic Cycle main page.

Macroorganisms
The teams must also be able to identify both immature and adult forms of certain macroinvertebrates and aquatic nuisance organisms, and know their importance as indicators of water and wetland quality. Division C teams must also know the general ecology, life cycles, and feeding habits of all these organisms. For more information about these macroorganisms, see the Macroorganism List

Each team is also responsible for knowing these same facts about the following Aquatic Nuisance Plants and Animals.

Wastewater Treatment
Treatment in the US costs $12 billion a year, and is expected to double in 10 years.

Septic-Tank Disposal Systems: This is the conventional method for treatment. A sewer line from the house leads to an underground septic tank in the yard. This tank is designed to separate solids from liquid, digest and store organic matter, and allow the treated sewage to seep into the surrounding soil. As the wastewater moves through the soil, it is further treated by the natural processes of oxidation and filtering.

This method can fail if the tank isn't pumped out when it's full of solids or if there is poor drainage in the surrounding soil.



Wastewater Treatment Plants: Raw sewage is delivered to the plant through a network of sewer pipes. Following treatment, the wastewater is discharged into rivers, lakes, or the ocean.



Wastewater treatment is divided into three categories: primary, secondary, and advanced. Primary and secondary treatment is required by law for all municipal plants in the US. When secondary treatment isn't enough to clean water, advanced treatment is used.

Nutrient Cycles/Biogeochemical Cycles
This event covers nutrient cycles such as the carbon, nitrogen, sulfur, and phosphorous cycle.

Analysis
A major part of Water Quality deals with the analysis of a particular body of water, such as a stream, for different properties. These properties include salinity, pH, alkalinity, phosphates, nitrates, turbidity, dissolved oxygen (DO), temperature, fecal coliform, total solids, and biological oxygen demand (BOD)

Salinity
Salinity is a property of water, which describes its salt concentration. Salinity is measured by dissolved salts in parts per thousand (ppt). Fresh water has a ppt of <0.5, which means that there are 0.5 molecules of dissolved salt for every 1000 molecules of solution, or 1 molecule of salt per every 2000 molecules of solution. Brackish water has a ppt between 0.5 and 30, saline water has a ppt between 30 to 50, and brine has a ppt of >50. The only water safe for human consumption is fresh water.

Constructing a Salinometer
In order to test salinity, your team must construct a homemade salinometer/hydrometer capable of measuring saltwater concentrations from 1-10%. Typically, this section will be worth about 5% of the test. The vast majority of salinometers are based on the principles of density and buoyancy. Since saline solutions contain dissolved NaCl, their densities are higher than that of distilled water. Due to the elevated density, the solution exerts a higher buoyant force, causing the hydrometer to float higher than in distilled water. There is a direct relationship between salinity and and buoyant force - the more saline the water, the higher your hydrometer will float.

To make a rudimentary salinometer, get a drinking straw and some clay. Place a ball of clay on one end of the salinometer, completely covering the opening of the straw. Then make some solutions of water and salt, with the salt concentration being between 0% and 10%, and mark the meniscus of the water solution on the straw with a permanent marker, Sharpie, etc. Repeat for any number of solutions for a more accurate calibration. The amount of clay and the length and diameter of the straw affect the distance between marks on the salinometer.

Note that this is not the only way in which to make a salinometer, and you may create and invent ways to do it yourself.

pH
The pH is a measurement of the hydrogen ion concentration in a substance. It is a logarithmic scale that ranges from 0 to 14, meaning that a solution with a pH of 5 has 10 times the concentration of hydrogen ions as a solution with a pH of 6. A pH of 0 to 7 is acidic, and a pH of 7 to 14 is basic. A pH of 7 is neutral.

pH is an important water quality indicator because organisms can only tolerate water that is not too acidic nor too basic. The normal pH of rivers in the United States is 6.5 to 8.5, and values between 6.0 and 9.0 can support life for fish and invertebrates. This makes acid rain an important factor in water quality, since it will make water more acidic, and once the pH value approaches 6.0, negative effects begin to appear. The natural environment of an area can also affect pH. Limestone is a base when dissolved in water, so it can neutralize the effects of acids. Volcanoes, geysers, and hot springs will make water more acidic, as well as the presence of sulfur in nearby minerals.

Alkalinity is the ability of a solution to neutralize an acid. There are several ions that contribute to alkalinity, including bicarbonate, carbonate, hydroxide, and phosphate. Thus, limestone contributes to alkalinity, since its formula is calcium carbonate, and carbonate is one of the ions listed above.

Competing
You may bring in one two-sided page of resource notes and 2 non-programmable/graphing calculators. You must bring Class 4 eye protection. You may also bring a salinometer as well.