NEIGHBORHOOD WATER QUALITY Lesson 2. Pollution and Water Quality Keywords: pollutants, water pollution, point source, non-point source, urban pollution, agricultural pollution, atmospheric pollution, smog, nutrient pollution, eutrophication, organic pollution, herbicides, pesticides, chemical pollution, sediment pollution, stormwater runoff, urbanization, algae, phosphate, nitrogen, ion, nitrate, nitrite, ammonia, nitrifying bacteria, proteins, water quality, pH, acid, alkaline, basic, neutral, dissolved oxygen, organic material, temperature, thermal pollution, salinity Pollution Sources Water becomes polluted when point source pollution. This type of foreign substances enter the pollution is difficult to identify and environment and are transported into may come from pesticides, fertilizers, the water cycle. These substances, or automobile fluids washed off the known as pollutants, contaminate ground by a storm. Non-point source the water and are sometimes pollution comes from three main harmful to people and the areas: urban-industrial, agricultural, environment. Therefore, water and atmospheric sources. pollution is any change in water that is harmful to living organisms. Urban pollution comes from the cities, where many people live Sources of water pollution are together on a small amount of land. divided into two main categories: This type of pollution results from the point source and non-point source. things we do around our homes and Point source pollution occurs when places of work. Agricultural a pollutant is discharged at a specific pollution comes from rural areas source. In other words, the source of where fewer people live. This type of the pollutant can be easily identified. pollution results from runoff from Examples of point-source pollution farmland, and consists of pesticides, include a leaking pipe or a holding fertilizer, and eroded soil. tank with a hole in it, polluted water leaving a factory, or garbage being Atmospheric pollution comes from dumped into a river. These sources small particles that are carried in the of pollution are easy to identify air. A good example of atmospheric because the cause of the pollution pollution is smog. These pollutants can be observed. are carried around the world by winds, and reach the ground through Non-point source pollution is more rain. Acid rain is rain that has a high common, and contributes more concentration of atmospheric pollution to surface water than does pollutants. ©PROJECT OCEANOGRAPHY 13 NEIGHBORHOOD WATER QUALITY FALL 2000 NEIGHBORHOOD WATER QUALITY Types of Pollution Nutrients such as phosphate-containing rocks Plants living in the water require a and from human sources such as sufficient supply of nutrients to grow fertilizers, pesticides, detergents, and mature properly. The most and industrial wastes. common nutrients found in our waters are nitrogen, phosphorous, Organic Pollution and carbon. Human sewage, animal waste, and plant residue also contain organic However, large amounts of nutrients material, which can pollute water. in the water can cause problems Bacteria in the water decompose the such as algae blooms. Algae is a organic material, producing general term for small, chlorophyll- additional nutrients for plant growth. containing plants such as seaweed This can cause further decreases in and pond scum. When a body of oxygen content in the water. Human water has a high level of nutrients, and animal wastes can also carry aquatic plants will grow and harmful bacteria and viruses that can reproduce quickly. If algae grows in spread diseases. high density on the surface it will block sunlight from reaching plants Pesticides and Herbicides at greater depths. This will cause the Pesticides and herbicides are used plants to die. When algae die, the to kill weed and insects on lawns and decaying process uses oxygen in the food crops. They also kill fish, birds, water. Decreasing the amount of and beneficial insects when they are dissolved oxygen will cause aquatic not used properly. They contribute to animals to die. water pollution through stormwater runoff. When it rains the water The process of aquatic overgrowth, washes these chemicals off the followed by death, decay, and lawns and into water bodies. oxygen depletion is called eutrophication. Eutrophication can result from human influences on the Chemical Pollution chemicals that enter our waters. This Chemical pollution is usually caused process causes an imbalance by improperly disposing of poisonous between plants and animals in the materials such as paints, batteries, water. automobile exhaust, tires, and household cleaners. The pollution Phosphates are one of the more from these materials can harm many common nutrients to move through organisms, including humans. the ecosystem in large quantities. Phosphates enter the waterways through runoff from natural sources ©PROJECT OCEANOGRAPHY 14 NEIGHBORHOOD WATER QUALITY FALL 2000 NEIGHBORHOOD WATER QUALITY Sediment Pollution the amount of sunlight available to Sediment pollution occurs when aquatic plants. Sediments are also loose soil is carried off streets, dangerous because they carry other parking lots, buildings, and pollutants such as chemicals from construction sites by rain. When lawns and petroleum products from these particles enter the water, they automobiles. clog the gills of fish, and decrease Stormwater Runoff Stormwater runoff is the leading Stormwater has become a problem cause of water pollution. When it due to increased urbanization. rains, the ground is not able to soak Urbanization occurs when streets, up all the water. This excess water parking lots, and buildings begin to flows into stormwater drains which cover the soil. These structures do often lead directly into nearby bodies not allow storm water to soak into of water such as streams, rivers, and the ground. When there is not oceans. As the rainwater flows over enough open space for water to soak paved surfaces it picks up in, stormwater runs over covered pesticides, fertilizers, bacteria, soil, surfaces, washing pollutants into grease, oil, and litter. lakes, rivers, and bays. Stormwater ©PROJECT OCEANOGRAPHY 15 NEIGHBORHOOD WATER QUALITY FALL 2000 NEIGHBORHOOD WATER QUALITY can be treated by using stormwater aquifer. Freshwater ‘floats’ on top of ponds. These man-made ponds the denser, or thicker, saltwater. collect and filter rainwater before it When large amounts of freshwater can reach a larger body of water. are removed from the aquifer the saltwater will move upward because Saltwater Intrusion it has less pressure (less freshwater) In coastal areas, groundwater can on top of it. Once the saltwater become contaminated through moves into the freshwater the saltwater intrusion. Some aquifers groundwater is contaminated and may contain a layer of saltwater becomes very expensive to clean. above or below the freshwater The Nitrogen Cycle Nitrogen, like phosphate, is This form of nitrogen can be easily essential to plants and animals for absorbed by plants. proper growth and productivity. The air we breathe is composed mainly Nirtrate is present as an ion, or of nitrogen gas (N2). However, this charged species in water. The form is impossible for aquatic plants nitrate ion is composed of a single to use. Therefore, most plants rely nitrogen atom and three oxygen on bacteria, which "fix" or convert the atoms (NO3). Nitrate forms the nitrogen gas found in the important materials necessary for atmosphere to a form called nitrate. life, such as proteins and vitamins. ©PROJECT OCEANOGRAPHY 16 NEIGHBORHOOD WATER QUALITY FALL 2000 NEIGHBORHOOD WATER QUALITY When animals digest these proteins nitrate. Ammonium oxidizers convert they are converted to ammonia ammonia to nitrite, and nitrifying (NH3). Ammonia in high bacteria convert nitrite to nitrate. concentrations in the body is toxic. Both types of bacteria require All organisms, including fish, must oxygen to perform these reactions. get rid of ammonia through Algae also help recycle nitrogen by excretion. Ammonia is also produced converting ammonia into plant when plants and animals decay. material. Harmful concentrations of ammonia hardly ever build up in Two kinds of bacteria work in natural waters due to recycling by sequence to transform ammonia into algae and bacteria. Water Quality Testing Water quality is a term used to pollutants, which are endangering describe the chemical, biological, plants and animals. Water quality and physical characteristics of water. has become an important issue Water quality is not simply "good" or because of the increasing population "bad", but usually is applied to its size. As the population increases so purpose. For example, water that is does development, which creates suitable for washing a car may not greater potential for harmful be suitable for drinking. For most substances to enter our water purposes water quality refers to supplies. water for drinking, swimming, and fishing. Chemical tests have been developed to determine water quality. The Often these days we hear about factors that affect water quality are illnesses from water contaminated by pH, dissolved oxygen, temperature, microorganisms and chemical and salinity. pH pH is a measure of a sample’s acidic) and 14 the lowest (most acidity and is the most commonly basic). used water quality test. Some examples of acids include vinegar and lemon juice. Basic pH is a measure of the hydrogen ion substances include baking soda and concentration, which is high in acids drain cleaner (lye). A substance that and low