The Effect of Different Levels of Nitrate and Phosphate

on the Macroinvertebrate Populations in Different Streams

                                  

            Phosphates and nitrates occur in small amounts in all aquatic environments and are required to maintain the growth and metabolism of plants and animals. However, in excess amounts, these minerals can prove to be quite harmful. Through the process of eutrophication, dissolved minerals and nutrients flow into streams, lakes, and other bodies of water. A good portion of these dissolved minerals consists of phosphates and nitrates. Levels of phosphates and nitrates that are intolerable to local organisms have been known to deplete dissolved oxygen levels by causing algae blooms. Eutrophication, bringing with it high amounts of phosphates and nitrates, is a main cause in the destruction of lake ecosystems around the world. (Ansar & Khad, 2005) Several scientists have studied mineral levels in different bodies of water, and have found that the levels of phosphates and nitrates heavily impact the overall health of the water and its inhabitants. (Yanamadala, 2005)

            First one must understand exactly how organisms use phosphates and nitrates. Proteins in organisms require nitrogen to function. Nitrogen is a very common gas, making up about 79% of Earth’s atmosphere. However, living things cannot use nitrogen in this state. They must use nitrogen that has been fixed through nitrogen fixation, in which atmospheric phenomena, industrial methods, or certain bacteria transform the unusable form of nitrogen into useful nitrogen compounds. Plants use these compounds, and animals can acquire these compounds by feeding on the plants. Phosphorus is an essential element in DNA, ATP, and RNA, so it is needed by all living things. Plants use phosphorus to form more complex cells, and animals can get phosphorus by feeding on these producers. (Schmid-Araya, 2003).

            How exactly does eutrophication indirectly affect aquatic life? It is already known that excess nutrients cause algal and bacterial growth. It also causes a burst of growth in plants and phytoplankton, forming a layer of green slime across the surface of bodies of water. This layer inhibits light movement into the water and also lessens the amount of oxygen that can get into the water from the air. Plants below the water’s surface may die from lack of light, and the resulting decay and decomposition of these plants causes the water to grow foul smelling and turbid. The loss of oxygen in the water causes aerobic organisms to suffer while anaerobic organisms are favored. More fish die from this loss of oxygen, and the total water quality of the water is lowered as the balance of life shifts. Eutrophic water is often scummy, cloudy, soupy-green in color, and overgrown with plants and algae. When an algal bloom resulting from phosphate and nitrate addition ends, the resulting decay of the algae often leads to the growth of disease-causing bacteria. Obviously, excess phosphates and nitrates significantly change the body of water for the worse. (Ansar & Khad, 2005)

            In a recent study of bodies of water near Morris Williams' Municipal Golf Course, located in Austin, Texas, showed the runoff of chemicals used to treat the turfgrass included significant amounts of phosphates and nitrates. The French drains located beneath the golf course are used to regulate and control underground runoff. While these drains typically do a good job of keeping pollutants away from the major water bodies in the area, the design of this drainage system and the way it directed the flow of water actually facilitated nitrate and phosphate movement to surface waters. This goal of this study was to quantify the flow of nitrates and phosphates from two French drains below the golf course and figure out the relationship between the data and the course’s layout and the management of the drains, as well as local seasonal climate patterns. The data showed that the nitrate levels coming from the drains were fairly low, but that seasonal changes played an important role in controlling the level of nitrate: nitrates were in much higher concentration during the winter months due to increased rainfall, turfgrass dormancy, and decreased microbial and bacterial activity. Phosphate levels were not as affected by the seasons as nitrate was. However, scientists were alarmed by the phosphate levels they found coming from the drainage system: they were significantly higher than those of most agricultural runoff sources. This could potentially cause great harm to nearby surface water systems and the many diverse organisms that inhabit them. (Balogh et al. 2006)

            Increased levels of phosphates and nitrates often indirectly harm the environment by causing bacterial growth and huge algae blooms. (Yanamadala, 2005) Harbor Lake Machado is located near Los Angeles, California. Many unique species call the lake home, and hundreds of migratory birds visit it annually. While organizations do their best to clean the water of Lake Machado, pollutants continue to pour in from storm drains and agricultural runoff. This brings large levels of phosphates and nitrates into the lake’s ecosystem, which most likely accounts for the recent rise in bacterial and algal growth in the lake. This body of water, located on a major migratory route, is said to be becoming increasingly dangerous for animals and plants. The phosphate and nitrate levels are well beyond standard safety limits set by the U.S. Environmental Protection Agency. Pollution of water bodies is almost entirely the fault of humans and industrialization. If high-mineral content runoff continues to pour into water from, the quality of water-dwelling organisms and that of the water itself will continue to decline. (Engel et al. 2006) Some new techniques, such as the resin-based system developed by Stormwater Management of Portland, Oregon that targets and removes dissolved phosphorus from stormwater runoff, are being developed to reduce the pollution that goes into bodies of water. (Kreuzer 2000)

                       

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ansar, A., & Khad, F. (2005, December). Eutrophication: An Ecological Vision.
     The Botanical Review, 71(4), 449-82.

Balogh, J., Fausey, N., Harmel, R., Hughes, K., & King, K. (2006, January/February).
     Nitrate-nitrogen and dissolved reactive phosphorus in subsurface drainage
     from managed turfgrass. Journal of Soil and Water Conservation, 61(1), 31-41.

Engel, B., Lim, K., & Tang, Z. (2006, January). Effects of calibration on L-THIA
     GIS runoff and pollutant estimation. Journal of Environmental Management,
     78(1), 35-43.

Kreuzer, H. (2000, September). Iron-infused media traps dissolved phosphorous.
     Pollution Engineering, 32(9), 25.

Schmid-Araya. (2003, September). Biogeochemical Cycles: The Nitrogen and the

      Phosphorus Cycles.

Yanamadala, V. (2005, November/December). Calcium Carbonate Phosphate Binding
     Ion Exchange Filtration and Accelerated Denitrification Improve Public
     Health Standards and Combat Eutrophication in Aquatic Ecosystems. Water
     Environment Research, 77(7), 3003-3012.