Water Quality Tests

Basic Overview of Our Water Quality Parameters:

• Animals: Animals can be used as an indicator for ecological health in and around the water. For example, if there were dead fish and creatures floating in water, it would be a sign that the water is not very supportive of life. Many organisms in the water are very sensitive to Ammonia and Nitrite, and somewhat sensitive to pH, and rapid increases in Salinity (salt) level, so if there is too much of either of these, animals will not flourish. However, if the water was teeming with life, it would be an indication that the water is able to support life well. Macro invertebrates, organisms without spines, can be especially sensitive or tolerant to pollution, some that are very sensitive are, Stonefly, Caddisfly, Water Penny, and Gilled Snail. Some that are not at all sensitive to pollution are, Midge fly Larvae, Black fly larvae, Leeches, and Lung Snails. Some that are some-what tolerant are, Crayfish, Beetle larvae, Scuds, Clams, Whirligig, and Sowbugs.

• Temperature: Temperature is an important factor to consider when assessing water quality. Water temperature exerts a major influence on biological activity and growth. Temperature governs the kinds of organisms that can live in rivers and lakes. All of these organisms have a preferred temperature range for the water that they live in. As the temperature of the water fluctuates from the organisms preferred temperature ranges, the number of organisms in the water decreases until the water is completely abandoned. Temperature is also important because of its influence on water chemistry. The rate of chemical reactions generally increases at higher temperatures. Warm water holds less dissolved oxygen than cool water, and may not contain enough dissolved oxygen for the survival of different species of aquatic life. Some compounds are also more toxic to aquatic life at higher temperatures.

• Turbidity: Turbidity is the most visible indicator of water quality. The turbidity of water can come from soil erosion, runoff, discharges, stirred bottom sediments or algal blooms. Clear water is usually considered an indicator of healthy water, unless it is a stream that has a naturally high level of suspended solids. High levels of suspended solids will cause an increase in water temperature and a decrease in dissolved oxygen levels. This is because the suspended particles will absorb more heat from solar radiation than the water molecules will, and this heat is then transferred to the surrounding water by conduction. Warmer water cannot hold as much dissolved oxygen as colder water, so the dissolved oxygen levels will drop. Turbidity can also inhibit photosynthesis by blocking out sunlight from trespassing through to plants in the water. Reduced photosynthesis causes less dissolved oxygen to be produced, which is unhealthy for the water and the organisms living in it. The lack of sunlight causes plants to die off, minimizing the amount of food organisms have to eat.

• Plants: Observing the plants around your site can tell you if the water is fresh or not. If most of the plants look dead then the water might not be clean. Which plants are there can also tell you what quality the water is. For instance, Rosemary can withstand high levels of salinity in water, American Holly trees are moderately tolerant, and American Beech trees slightly. For finding out what plant is what you can use a field guide or take a small sample or photo back with you.

• Salinity: Salinity is the ratio of salt in water to the amount of water. Specifically, it is measured in ppt (parts per thousand). It is important to study the salinity in water because of the bad effects on fresh water wildlife that can happen if the salinity level increases too rapidly.  Animals that are not adapted to saltwater will often die of dehydration, because their bodies try to even the amount of salt inside them with the amount outside, pushing out their own body fluid to achieve this. Testing for salinity in the water is important for the plants and animals living off of it. If the salt in the water is too high or too low the fish and bacteria living in the water can be hurt. During the snowy months the rock salt used to melt the snow can get into the water and create more salinity in the water.

• Bacteria: Coliform Bacteria is in many things including plants, dirt, and animals. However it is most common in fecal matter. This means that if the test for coliform in water is positive there is a large amount feces in the water. Coliform also can carry diseases. If a water test comes positive for coliform the water is not safe to drink. Chemical Reaction Behind the Coliform Bacteria Test: The coliform bacteria test kit works not by reacting with the bacteria, but with their metabolism. The tablet that dissolves into the water sample is made up of food for the bacteria, a pH indicator, and a gel-like substance (caesin). If there are any coliform bacteria they will consume the tablet and as they do they will release carbon dioxide (CO2). This CO2 gets trapped in the caesin, causing it to rise and lose density. The CO2 lowers the pH level, therefore changing the initial color of red to yellow, and signaling a positive test result.

• pH: pH is the test of acidity in the water. We test the pH by first getting a sample of the water. We then drop 3 drops of a chemical solution into a 5 mL test tube of the water we sampled from alewife brook. We then shake the vial vigorously for a few seconds until the color is easily identifiable. We then match it up to a color chart and see the pH level. PH is on a scale come on 1-14, 1 being the most acidic and 14 being the least. 7 is the neutral measurement. You always want it to be neutral because if it's too little or too much It can be detrimental to the organisms in the water.The pH test works because the liquid you drop in sees how many hydrogen ions are in the water. The higher amount of hydrogen ions makes the water more acidic and lower on the PH scale. Hydrogen ions are when a atom of hydrogen has its electron taken away, electrons have a negative charge making the ion positively charged.

• Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD): DO and BOD are both important to study when it comes to water quality because DO measures the amount of Dissolved Oxygen in the water and Biochemical Oxygen Demand is the amount of oxygen consumed by the microorganisms organic matter in the water. They both indicate the healthiness of the water.

• Nitrogen Compounds (Overview) Ammonia comes from the breakdown of pee. Of these three main nitrogen compounds, Ammonia is the most toxic, Nitrate is the second most toxic, and Nitrate is the third, being not nearly as toxic as the first two. Ammonia can then be changed to Nitrite by bacteria, which can then be changed to Nitrate. 

• Ammonia: Ammonia is important to test for in water because too much of it can be bad for aquatic life. Ammonia is a highly toxic chemical compound and is one of the nitrogen compounds. Ammonia can grow from various forms of waste, human or animal. In other words, Ammonia comes from urine and fertilizer. Once the Ammonia is formed, bacteria called Nitrosomonas can convert that ammonia to nitrite, another nitrogen compound toxic to life. Another species of bacteria, Nitrobacteria can then convert this nitrite into nitrate, a nitrogen compound that is far less toxic.

•  Nitrite: is one of the many ways we test the water at Alewife brook. Nitrite is part of the Nitrogen cycle which goes, Ammonia -> Nitrite -> Nitrate, Ammonia is toxic to the water and the animals in it. Nitrite's chemical formula is NO2-. 

• Nitrate: One of the most important uses of Nitrate is its effectiveness in fertilizer.