Nutrient Pollution

<body> <p align="center"><strong>What is Nutrient Pollution</strong></p> <ul> <li><a href="nutr1.cfm#What">What are nutrients?</a></li> <li><a href="nutr1.cfm#Ecosystem">How are nitrogen and phosphorous used in the ecosystem?</a></li> <li><a href="nutr1.cfm#Howpollutants">How can nutrients become pollutants to the Bay and its rivers?</a></li> <li><a href="nutr1.cfm#Sources">What are the sources of nutrients?</a></li> <li><a href="nutr2.htm" target="_top">How is the Bay Program involved in nutrient reduction?</a></li> </ul> <hr> <p><a name="What"></a><b>What Are Nutrients?</b></p> <p>Nutrients, like nitrogen and phosphorus, occur naturally in water, soil and air. Just as the nitrogen and phosphorus in fertilizer aids the growth of agricultural crops, both nutrients are vital to the growth of plants within the Bay and rivers. </p> <hr> <p><a name="Ecosystem"></a><b>How are nitrogen and phosphorous used in the ecosystem?</b></p> <p>Nitrogen is essential to the production of plant and animal tissue. It is used primarily by plants and animals to synthesize protein. Nitrogen enters the ecosystem in several chemical forms and also occurs in other dissolved or particulate forms, such as in the tissues of living and dead organisms. </p> <p>Some bacteria and blue-green algae can extract nitrogen gas from the atmosphere and transform it into organic nitrogen compounds. This process, called nitrogen fixation, cycles nitrogen between organic and inorganic components. Other bacteria release nitrogen gas back into the atmosphere as part of their normal metabolism in a process called denitrification. Denitrification removes about 25 percent of the nitrogen entering the Bay each year. </p> <p>Phosphorus is another key nutrient in the Bay's ecosystem. In the water, phosphorus occurs in dissolved organic and inorganic forms, often attached to particles of sediment. This nutrient is essential to cellular growth and reproduction. Phytoplankton and bacteria assimilate and use phosphorus in their growth cycles. Phosphates, the organic form, are preferred but organisms will use other forms of phosphorus when phosphates are unavailable. </p> <p> In the presence of oxygen, high concentrations of phosphates in the water will combine with suspended particles. These particles eventually settle to the Bay bottom and are temporarily removed from the cycling process. Phosphates often become long-term constituents of the bottom sediments. Phosphorus compounds in the Bay generally occur in greater concentrations in less saline areas, such as the upper part of the Bay and tributaries. Overall, phosphorus concentrations vary more in the summer than winter. </p> <hr> <p><a name="Howpollutants"></a><b>How can nutrients become pollutants to the Bay and its rivers?</b></p> <p>Although nutrients are essential to all plant life within the Bay, an excess of these same nutrients can be harmful. This is called "nutrient pollution". </p> <p>Nutrients have always existed in the Bay, but not at the present excessive concentrations. When the Bay was surrounded primarily by forest and wetlands, very little nitrogen and phosphorus ran off the land into the water. Most of it was absorbed or held in place by the natural vegetation. Today, much of the forests and wetlands has been replaced by farms, cities, and suburbs. As the use of the land has changed and the watershed's population has grown, the amount of nutrients entering the Bay's waters has increased tremendously. </p> <p>Excess amounts of phosphorus and nitrogen cause rapid growth of phytoplankton, creating dense populations, or blooms. These blooms become so dense that they reduce the amount of sunlight available to submerged aquatic vegetation. Without sufficient light, plants cannot photosynthesize and produce the food they need to survive. Algae may also grow directly on the surface of SAV, blocking light. </p> <hr> <p><strong>What are the <a name="Sources">Sources</a> of Nutrients?</strong></p> <div align="center"> <center> <table cellspacing="2" cellpadding="6" cols="3"> <tr> <td> <p align="center"><img src="images/tractor.jpg" alt="tractor.jpg (7899 bytes)" width="157" height="108"><br> <font face="Arial" size="1">Farmland</font> </td> <td> <p align="center"><img src="images/city.jpg" alt="city.jpg (10711 bytes)" width="156" height="107"><br> <font face="Arial" size="1">Urban Landscape</font> </td> <td> <p align="center"><img src="images/source.jpg" alt="source.jpg (8342 bytes)" width="155" height="107"><br> <font face="Arial" size="1">Wastewater Treatment Plant</font> </td> </tr> </table> </center> </div> <p>The main causes of the Bay's poor water quality and aquatic habitat loss are elevated levels of two nutrients, nitrogen and phosphorous. These nutrients occur naturally in soil, animal waste, plant material, and even the atmosphere. In addition to these natural sources, sewage treatment plants, industries, vehicle exhaust, acid rain, and runoff from agricultural, residential and urban areas contribute nutrients to the Chesapeake Bay and its rivers.</p> <p>Virtually all individuals and industries in the watershed, and some even beyond the watershed, contribute the nutrients that ultimately reach the Bay.  In the Bay region, excess nutrients are supplied to the system through two sources: <strong>point</strong> and <strong>nonpoint</strong> sources.  <ul> <li>A <strong>point source</strong> is a specific location or point of entry, such as a pipe, where nutrients enter waterways.  Point sources, like industrial sites and wastewater treatment facilities, are usually federally regulated.   </li> <li><strong>Nonpoint sources</strong> deliver nutrients from broad areas of the watershed, rather than from one specific point, which makes these sources very difficult to control.  For example, storm water picks up nutrients from cities to rural areas as it pours over roofs, through suburban developments, over eroding streambanks, through farm fields and into rivers.  </li> </ul> <div align="center"> <center> <table border="1" cellpadding="0" cellspacing="0" bgcolor="#C6C68C" width="100%"> <tr> <td><strong>Other Sites of Interest:</strong> <ul> <li><a href="http://www.agnr.umd.edu/users/agron/nutrient/" target="_top">Maryland Cooperative Extension's Agricultural Nutrient Management Program</a></li> <li><a href="http://wwwrvares.er.usgs.gov/nawqa/circ-1136/h8.html" target="_top">National Water-Quality Assessment Program</a> - USGS</li> <li><a href="http://www.state.va.us/%7Edcr/sw/index.htm" target="_top">Soil and Water Conservation Programs</a> - Virginia Department of Conservation and Recreation</li> <li><a href="http://www.mda.state.md.us/geninfo/gen5.htm" target="_top">Maryland Department of Agriculture - Environmental Programs</a></li> <li><a href="http://www.cbf.org/state_of_the_bay/pollution_factor.htm" target="_top">The Pollution Factor: What we put into the Bay</a> - Chesapeake Bay Foundation</li> <li><a href="http://www.nhq.nrcs.usda.gov/land/env/wq2.html" target="_top">Water Quality: Nutrients</a> - USDA</li> </ul> </td> </tr> </table> </center> </div> <hr noshade> <p align="center"><font size="2">To bookmark this page, please use this URL: <a href="http://www.chesapeakebay.net/nutr1.htm" target="_top">http://www.chesapeakebay.net/nutr1.htm</a> </font></p> <p align="center"><font size="2">For more information, contact the Chesapeake Bay Program Office, 410 Severn Avenue, Suite 109, Annapolis, MD 21403 /  Tel: (800) YOUR-BAY /   Fax: (410) 267-5777. </font></p> <p align="center"><font size="2"><a href="javascript:print()"><img src="images/print.gif" width="34" height="38" border="0" alt="Print Current Page" align="right"></a><a href="http://www.chesapeakebay.net/directions.htm" target="_top">Directions to the Bay Program Office</a><a href="http://www.chesapeakebay.net/cims" target="_top"><img src="images/cims1.gif" height="19" width="51" border="0" align="left"></a></font></p> <p align="center"><font size="2">Last modified: 09/18/01</font> <p> </p> </body>