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Introduction
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Fertilizer Numbers
On August 27, 2009 the State-Epa Nutrient Innovations Task Group issued an urgent call to action to Epa Administrator Lisa Jackson. The task group studied documented levels of excess nutrients in our nations waterways. Current, and past, efforts to control these pollutants have been inadequate on the national and statewide scale. Efforts to date have been predominantly "regulation at the pipe" and have not addressed the non point sources that are the root cause of elevated concentrations of nutrients in ground and surface waters. Nutrient pollution significantly impacts all of us. It impacts our drinking water, our recreational water, such as beaches and rivers and lakes, and it affects, and even kills, aquatic life. None of us want a bunch of dead rivers, but what can we do? What are Nutrients? Nutrients are elements that are primary to life. Being primary to life they are also primary components of the molecules that make up living tissue. Decaying organic matter and human and animal waste are primary sources of nutrient pollution in ground and surface water. The chemicals we produce and use in day-to-day life may also comprise nutrients, as well as the fertilizers that we spread on our yards and farms. It is the broad application of fertilizers, the animal feeding lots, the overall use of septic tanks, and runoff water from rainfall to school kid carwashes that are responsible for the immeasurable amounts of nutrients that find their way into the watershed. These are the non-point sources that cannot be no ifs ands or buts regulated. For 30 years the Clean Water Act has regulated industrial and municipal effluents. Limits are getting lower and lower. It is easy to take a sample at the end of a pipe. It's easy to know where the sample comes from, and who is responsible if pollutants are too high. Unfortunately, 30 years of regulation of commerce has not significantly reduced the problem. Obviously, there are other sources. And the sources are us. Our everyday activities of washing our cars, fertilizing and watering our lawns, irrigating farms, and even desiring green golf courses. The primary nutrients that are in the fertilizers and detergents are entering the groundwater, not by an industrial effluent but down the gutter and into the storm drain. Rainfall is washing nutrients into creeks and rivers and carrying them into basins such as the Gulf of Mexico or Chesapeake Bay. Hypoxic zones, also known as dead zones, are forming where excess nutrients are deposited. The excess nutrients cause a rapid growth of algae. The algae grow so rapidly that they cut off their own light and die. This is a normal, geologic process, occurring more rapidly than normal. As the algae dies it decays and the decay process consumes oxygen. Without oxygen aquatic life cannot breathe. What is Nutrient Pollution? Nitrogen and Phosphorus are the primary elements referred to when discussing nutrient pollution. Other primary elements, such as carbon, silica, and sulfur are not included in this discussion. Organic nitrogen and organic phosphorus are linked with the organic matter we part and record as Toc. Nitrogen and phosphorus are primary elements in Dna, Rna, and nitrogen is a major component of protein and urine. Nitrogen and phosphorus occur as both water-soluble and water insoluble species. Unfortunately, both soluble and insoluble come to be bioavailable. Seeing at this table, we see that Nitrogen and Phosphorus are somewhat similar chemically, for instance, the plus 5 ions known as nitrate and phosphate are very stable and very water-soluble. Nitrogen Nitrogen is an primary nutrient for plant growth ranking only behind carbon, hydrogen and oxygen in total quantity needed. The nitrogen gas manufacture up about 80% of the climate is largely inert and unavailable to life directly. Lightning will turn small amounts of nitrogen to nitrate. Nitrogen in fertilizers largely comes from the chemical reaction in the middle of nitrogen and hydrogen gas to form ammonia. The ammonia can then be oxidized to form nitrate. Fertilizers will often comprise ammonia, nitrate, and/or urea as the sources of nitrogen. Organic matter, referred to as humic matter, manure, mulch, etcetera contains about 5% Nitrogen. This nitrogen is moderately converted to ammonia by bacteria and is ultimately oxidized to nitrite then nitrate. During a storm event, or During irrigation the nitrate in soil is no ifs ands or buts leached into the runoff. Dissolved inorganic nitrogen includes nitrate, nitrite, and ammonia. Dissolved organic nitrogen includes water-soluble proteins, amines, amides, and so forth. Basically decayed organic life and some man made chemicals that are dissolved in water. Total Organic nitrogen is the sum of dissolved organic nitrogen and particulate organic nitrogen. Particulate organic nitrogen is, well obviously, the insoluble organic compounds, or organic matter, in the water. Total Dissolved Nitrogen is the dissolved organic nitrogen plus the dissolved inorganic nitrogen, and Total nitrogen includes all of the above. Notice, there is no ifs ands or buts no such thing as total inorganic nitrogen. This is because inorganic nitrogen compounds are all water-soluble. Chemical analysis of Nitrogen Compounds Total dissolved nitrogen, or the supervene you get when analyzing total nitrogen on a filtered sample consists of dissolved organic nitrogen, nitrate, nitrite and ammonia. Methods used to settle Tdn normally rely on an alkaline persulfate digestion that converts all of the nitrogen present to nitrate and then the nitrate is determined colorimetrically. Analyzing inorganic nitrogen alone will only recover about 30 - 40 % of the total dissolved nitrogen in the natural environment. Sewage treatment and industrial plant effluents, on the other hand, are predominantly inorganic nitrogen (nitrate) since the treatment process is designed to wholly oxidize dissolved organic nitrogen and ammonia to nitrate. Total nitrogen, or the supervene you get when analyzing total nitrogen on a non-filtered sample consists of dissolved organic nitrogen, nitrate, nitrite and ammonia plus particulate nitrogen. Since all inorganic nitrogen compounds are soluble, particulate nitrogen is approximately entirely organic nitrogen, or Pon. Methods used to settle Tn can rely on the same alkaline persulfate digestion used to settle Tdn with the irregularity that samples are not filtered. Since samples are not filtered, the automated version is not applicable if there is a primary amount of sediment (or solids) in the sample. In other words, the automated inline digestion methods part Tdn and are only applicable if Tdn and Tn are essentially equal (there is no particulate organic nitrogen). The Din fraction, measured to fancy the Total Organic Nitrogen article can be, and should be, analyzed on a filtered sample. Remember that there is no such thing as Total Inorganic Nitrogen since it is equal to Dissolved Inorganic Nitrogen. Another infamous parameter in the total nitrogen world is, of course, Tkn (Total Kjeldahl Nitrogen). Tkn, as routinely used, does not part nitrate or nitrite. It is essentially a part of organic nitrogen plus ammonia nitrogen. Tkn is the classical, if you will, analysis for total organic nitrogen. Tkn has its roots in food and feed analysis as a way to quantify the amount of protein. Tkn has been extrapolated to environmental analysis and is the regulated parameter for Total Nitrogen. Unless steps are taken to comprise nitrate and nitrite the quarterly Tkn formula does not part it. Tkn essentially measures organic nitrogen and ammonia. Tkn is enough in Potw or municipal influents because these samples rarely have nitrate in them anyway. Recall the nitrogen reactions. An influent to a Potw will comprise particulate nitrogen, dissolved organic nitrogen, and ammonia. The particulate nitrogen mostly settles as sludge removing it from the equation. Organic nitrogen and ammonia are oxidized to nitrate During the treatment process. The Tkn digestion boils the sample in concentrated sulfuric acid in the presence of a metallic catalyst to speed the reaction. Potassium sulfate is added to raise the boiling point to about 380 C. The digestion will not wholly recover all organic nitrogen compounds manufacture the Tkn supervene no ifs ands or buts less than or equal to the Tn determined by alkaline persulfate oxidation. According to the Epa definition, Total Nitrogen equals Tkn plus nitrate plus nitrite. Phosphorus Phosphorus is an primary nutrient found in living organisms as part of Dna among other prominent molecules. Phosphorus is all the time found in nature bound to other atoms and normally as the inorganic phosphate. It is phosphate that is ready to plants and used as a fertilizer. It is phosphate that is consumed by algae and has the possible to cause algal blooms. Measurement of total phosphorus is prominent because it can, with time, turn to bioavailable soluble phosphate. Dishwashing, laundry, and many hand detergents and/or soap comprise phosphorus. The phosphorus article in detergent can be as high as 8.7%. Phosphate is a very productive way to enhance soap quality, especially in waters that comprise high amounts of calcium and magnesium. Unfortunately, the phosphates in these detergents find their way into the environment. In the 1970's green rivers and lakes were becoming tasteless and phosphate usage in soaps began its eventual reduction. Although there is not a federal ban on phosphate is soap many states are taking action. For example, Washington State has small the amount of phosphate in dishwasher detergent to 0.5% Chemical analysis of Phosphorus Phosphorus can exist in water in distinct forms. The suitable formula for phosphorus is meant to part only phosphate, also called reactive phosphate. This is because what is no ifs ands or buts measured is defined by the molybdate reaction itself. Phosphorus species are considerable from each other empirically by filtration, and then a series of digestions that selectively turn phosphorus to phosphate. After the digestion phosphate is measured. Thus, to analyze organic phosphorus only, one digests for total phosphorus in one sample aliquot, and hydrolysable phosphorus in Another aliquot. Reactive phosphate is then determined in each absorb and Organic Phosphorus is calculated by difference. Total Phosphate is water-soluble. Instrumental methods need that samples be filtered, or the turbidity and/or solids will interfere. Therefore to accurately part total phosphate you must filter the sample. Since total reactive phosphorus is equal to filterable reactive phosphorus the results are the same. Remember though, that for best results, filtration should be in the field. The part for the total analysis is not filtered. If the particulates (Tss or Ss) are high, then continuous flow methods should not be used for the analysis of Total Phosphorus. Total phosphorus is batch digested that converts all phosphorus compounds to phosphate. The absorb is filtered and phosphate is then measured, normally by molybdenum blue. The continuous flow formula for Tdp utilizes 254 nm Uv irradiation to support in the digestion of organic material. Since continuous flow methods cannot be used to adequately absorb samples containing high amounts of solids and continuous digestion should not be used unless the total phosphorus is essentially equal to the dissolved phosphorus. Tkn is the classical digestion for total organic nitrogen. The Tkn absorb can also be used to analyze for total phosphorus. The advantage in this is not added recovery, for the acid persulfate quantitatively recovers all of the total phosphorus. The only advantage in the Tkp is the ability for the laboratory to test for Tkn and Tp in a singular digest. The perceived advantage is time and labor savings. Because of the higher acid and salt concentration of the resulting Tkp absorb compared to persulfate digests, Tkp detection limits are normally higher that limits found by persulfate. The other advantage to Tkp is, of course, that it is Epa approved. All of the colorimetric methods used for the Measurement of phosphate by molybdenum blue are very dependent upon final acid concentration and the amount of molybdate. Attempts made at analyzing total phosphorus digests without particular concentration to acid concentration are often not successful. After the digestion is complete, you are measuring orthophosphate. Any formula used to part phosphate can be used. The question with extending a total P Measurement to Ion Chromatography, for instance, comes from the inordinate sulfate ion introduced in the digestion. Earlier methods utilizing persulfate in sulfuric acid neutralized the sample and then analyzed orthophosphate. Some continuous flow methods part the phosphate in the acid clarification adjusting the acid in the reagent accordingly. The Tkp digestions have no ifs ands or buts only been tested using a mercury catalyst, and excess chloride must be added to preclude interference from the mercury. Like Tkn, the blue color of a copper catalyst may interfere with the method. The auto dialysis formula helps to control the final acid concentration and some of the residual color introduced by the copper. Dialysis is essentially an online dilution prominent to a higher detection limit than the cleaner persulfate digest. To sum up, for lower total phosphorus numbers (say below 0.1 ppm) it is recommended to use the acid persulfate digestion because the matrix will be easier to control and work with. For concentrations above 0.1 ppm, the Tkp digestion is adequate. Conclusion The clean water act was signed amid stories of weighty fish kills and rivers catching on fire. We all know that these things rarely happen in the Us anymore. We have monitored sewage treatment effluents and in many cases applied numerical maximums on the amount of nutrients that can be discharged. We still have a ways to go. Our chemical analysis methods were written for very polluted water. The methods we use were not validated at the lower concentration levels we need to part today. Many of the conditions of these methods assume higher concentrations will be present, and the previous rigid nature of the Clean Water Act rules did not let us turn anything. Fortunately, in 2007 the Epa added Part 136.6 to the Cfr allowing us to make modifications to our nutrient methods providing the modifications enhance formula performance. These modifications are going to allow us to monitor more water, with great accuracy and detection limits. We have more to go, because regulation of point sources has not solved the problem. Much of the question is the non point sources we call storm water run off and irrigation water. We need to watch what we do when we apply fertilizers and watch what goes down our storm drains. But more importantly, what we need is increased monitoring of our rivers and streams. The only way we can begin to solve our problems is to know exactly what they are. To understand this question we need more data, and the data we need is accurate, low level quantitative analysis of nutrients.
I hope you obtain new knowledge about Fertilizer Numbers. Where you possibly can put to utilization in your evryday life. And above all, your reaction is passed about Fertilizer Numbers. Read more.. Introduction to Nutrient Pollution.
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