Phosphorus and Nitrogen

Download Phosphorus and Nitrogen

Post on 12-Jan-2016




0 download

Embed Size (px)


Phosphorus and Nitrogen. Phosphorus. How is P used in organisms? Biomolecules ADP and ATP nucleic acids phospholipids (cell membranes) apatite (bones and tooth enamel). Forms of Phosphorus. Phosphorus in aquatic systems is usually categorized how we measure it. - PowerPoint PPT Presentation


<ul><li><p>Phosphorus and Nitrogen</p></li><li><p>PhosphorusHow is P used in organisms?BiomoleculesADP and ATPnucleic acidsphospholipids (cell membranes)apatite (bones and tooth enamel)</p></li><li><p>Forms of PhosphorusPhosphorus in aquatic systems is usually categorized how we measure it.Dissolved P = Any P that goes through a 0.45um filterPO43- polyphosphatesDissolved organic phosphates</p><p>Particulate P = Any P that is retained on the filter in algae, zooplankton, detritus, attached to sediment particles.</p><p>Total P = Dissolved P + Particulate P</p><p>Reactive P = P that reacts with molybdenum to form a blue color. </p><p>The most commonly measured forms of P are Total Phosphorus (TP) and Dissolved Reactive Phosphorus (DRP)</p></li><li><p>Limiting nutrientsTheoretically, phosphorus is usually the most limiting nutrient in freshwater systems as determined by Liebigs Law of the Minimum and Ecological stoichiometry</p></li><li><p>Liebig LawGrowth is limited by the nutrient that is in shortest supply.PNFeC</p></li><li><p>Limiting nutrientsEcological stoichiometryRatios of elements in plankton and other organismsImportant in addition to Liebigs law</p></li><li><p>Stoichiometry gives the recipe for phytoplanktonCake Example2 1/4 cups sifted cake flour 2 teaspoons baking powder 1/2 teaspoon salt 1/2 pound Butter2 cups sugar 4 large egg yolks 2 teaspoons vanilla 1 cup sour cream 4 large egg whites </p></li><li><p>Recipe for phytoplankton is the Redfield RatioIn the 1950s Alfred Redfield found in the deep ocean an average phytoplankton composition (by number of atoms) of C H O N PS Fe 106263 110 161 0.7 0.01</p><p>Note that C, H, O, and N are required in greater proportion than P.Why then are these NOT the generally nutrient limiting? </p></li><li><p>In freshwater systems P is usually limiting because the amount of P available to primary producers is much less than the amount required relative to the other elements.P makes up only ~1% of organic matter which implies that if nothing else is limiting, then increasing P can theoretically generate &gt;100X the weight of added P in algaeC H O N P S Fe 106263 110 161 0.7 0.01</p></li><li><p>2 1/4 cups sifted cake flour 2 teaspoons baking powder 1/2 teaspoon salt 1/2 pound Butter2 cups sugar 4 large egg yolks 2 teaspoons vanilla 1 cup sour cream 4 large egg whites Suppose you were a baker and wanted to sabotage a rival baker by stealing supplies from his storehouse. You can carry 50 lbs. of any ingredient with you. What do you steal in order to prevent him from making the most cakes?The Burglar Baker</p></li><li><p>2 1/4 cups sifted cake flour 2 teaspoons baking powder 1/2 teaspoon salt 1/2 pound Butter2 cups sugar 4 large egg yolks 2 teaspoons vanilla 1 cup sour cream 4 large egg whites i.e. If you have plenty of everything else, then with only teaspoon of salt, you can bake a cake.</p></li><li><p>Phosphorus and Lake ClassificationThe productivity of a lake is often determined by its P loading and its volume (mean depth)</p></li><li><p>Lake Productivity ClassificationTotal Phosphorus mg/LUltra-oligotrophic100</p></li><li><p>Sources of PhosphorusWeathering of calcium phosphate minerals, especially apatite [Ca5(PO4)3OH] from sediments of ancient oceans. There are no important gaseous sources of P.Anthropogenic P is now often much greater than natural inputs of P in many watershedsSewage, agriculture, etc.</p></li><li><p>Sources of Phosphorus</p><p>Increased production of algae due to increased Anthropogenic P input is cultural eutrophicationAnthropogenic P may come from point sources (think of a pipe)nonpoint sources (diffuse, like agriculture runoff)</p></li><li><p>Point and Nonpoint</p></li><li><p>External vs. Internal P LoadingLoading refers to input of a nutrient per unit timeUsually calculated for rivers as concentration x flowExternal loading refers to sources outside the lake (as in previous slide)If all external sources of P were removed, a lake would continue to grow algae for many years. This is because P is recycled within the lake. This recycling is termed Internal Loading</p></li><li><p>Lake sediments can trap P under oxic conditions or release P under anoxic conditionsP diffusionDiffusion BarrierOxygen profile of sediments in oxic conditions</p></li><li><p>Internal P LoadingP may be recycled in the food web several timesPhytoplankton are extemely efficient at absorbing any P that is released by excretion or decompositionEventually P will be lost from lake either by outflow or by sedimentation to the lake bottom.P is bound in lake sediments under oxic conditions, but may be regenerated from sediments under anoxic conditions (iron and microbes play an important role) </p></li><li><p>Internal P LoadingDeep lakes with oxic hypolimnia and long WRT may retain 70-90% of incoming P in the sedimentsLakes with Anoxic hypolimnia retain only half as much P as lakes with oxic hypolimniaTherefore external loading may result in a positive feedback loop that amplifies </p></li><li><p>Positive Feedback Loop</p></li><li><p>BioturbationPhysical re-suspension by organisms living in oxic sediments may also increase the regeneration of Phosphorus from sediments into the overlying waterJ. ChaffinWithout MayfliesWith Mayflies</p></li><li><p>Phosphorus RemediationEutrophication can be ugly: high algal biomass (sometimes toxic), hypoxia, fish kills, foul smellsOne answer is to reduce P loading byRemoving P from waste water (tertiary treatment)Diverting waste water (see Lake Washington)Using natural or constructed wetlands to trap PUsing buffer strips to trap agricultural runoffUsing pumps to aerate the hypolimnion </p></li><li><p>Wastewater Addition of alum to precipitate P</p></li><li><p>Buffer NRCS</p></li><li><p> Hypolimnion Aeration</p></li><li><p>The importance of the Maumee River watershed in phosphorus loading to Lake Erie</p></li><li><p>D. Dolan, LEMN conf. 2010</p></li><li><p>A look at P in the Maumee River(from P. Richards and D. Baker, NCWQR)Study completed in 1995 showed almost all trends improving, now they are getting worse.</p></li><li><p>Both river flow and DRP concentration have increased, therefore much greater DRP loading</p></li><li><p>The Maumee River watershed is causing a high degree of stress to Lake ErieJ. Kelly, LEMN Conf. 2010</p></li><li><p>Where is the dissolved P coming from? Investigation by the Ohio Phosphorus Task ForceAgricultureConservation TillageReduces soil erosion, butFertilizer remains near the soil surface and is more easily washed into tributaries</p></li><li><p>Stratification of P in soils</p></li><li><p>Conservation Tillage may have unintentional side effects</p></li><li><p>Where is the dissolved P coming from? Investigation by the Ohio Phosphorus Task ForceAgricultureConservation TillageFertilizer is not incorporated into the soil and is more easily washed into tributariesFall application of fertilizersContinuation of old P-building practiceCAFOS (concentrated animal feeding operations)Produce large amounts of animal waste with poor waste treatment practicesMunicipalitiesCombined sewer overflows (CSOs)Addition of P to water supply as anti-corrosive</p><p>See Ohio Lake Erie Phosphorus Task Force Final Report</p></li><li><p>The Microcystis-Anabaena bloom of 2009 was the largest in recent years in our sampling region </p><p>2011until 2011</p></li><li><p>Phosphorus loading is important, but what about Nitrogen?Phosphorus remains high throughout the growing season.Nitrogen loading and concentration drop during the summer, leading to Nitrogen-limited conditions.</p><p>****************************</p></li></ul>


View more >