• TN:Total Nitrogen

  TN: TPN (Total particulate nitrogen) + TDN (Total dissolved nitrogen). Dissolved nutrients are nominally defined as those that pass through a 0.45 micron filter. Particulate nutrients are those nutrients that filter out. Excess nutrients, such as nitrogen, in a system can lead to eutrophication.

  
  
  
• N+N: Nitrate + Nitrite
  N+N: (Nitrate NO3 + Nitrite NO2) Nitrate cannot be measured directly. It is first reduced by chemical reduction to nitrite and then measured colorimetrically. Nitrate test results are expressed this way to indicate "nitrogen in the form of nitrate".
  
  
  
• TDN: Total Dissolved Nitrogen

  TDN: DON (Dissolved Organic Nitrogen) + DIN (Dissolved Inorganic Nitrogen) This is a component of Total Nitrogen (TN) in a system.

  Common sources of excess inorganic nitrogen in a system include fertilizer runoff, leacheate from landfills, and urban stormwater runoff. Common sources of organic nitrogen include leaky septic systems and runoff from livestock.

  
  
  
• TP: Total Phosphorous

  TP: TPN (Total particulate phosphorus) + TDP (Total Dissolved Phosphorous) Phosphorous occurs in natural waters in the form of phosphates, naturally and unnaturally. Dissolved nutrients are nominally defined as those that pass through a 0.45 micron filter, while particulate nutrients are those nutrients that filter out.

  Excess nutrients such as phosphorous in a system can lead to eutrophication. Biscayne Bay is particulary sensitive to excess phosphorous, as research indicate it is a phosphorous-limited system.

  
  
  
• PO4: Phosphate
  PO4: Phosphorous occurs in natural waters in the form of phosphates. See TP Total Phosphorous above for more information on PO4.
  
  
  
• TDP:Total Dissolved Phosphorous

  TDP: DON (Dissolved Organic Phosphorous) + DIN (Dissolved Inorganic Phosphorous) This is a component of Total Phosphorous in a system.

  Phosphates in our waterways come from industrial effluent, detergent wastewater from residences, and fertilizers applied to agricultural and residential lands. Organically bound phosphorous come from plant and animal matter and wastes.
  

  
  
  
• DOC: Dissolved Organic Carbon
  DOC: The decomposition of organic matter in soil, and its chemical interaction with water leads to dissolved organic carbon in water. Waters contaminated with runoff from landfills or septic systems contain high levels of dissolved organics, resulting in high DOC rates.
  
  
  
• NH4: Ammonia
  NH4: High levels of ammonia can be toxic to invertebrates and fish. The nitrogen in ammonia can also contribute to excess nutrients in a system, which can lead to eutrophication.

High concentrations of Ammonia usually results from polluted stormwater runoff from urbanized areas, sewage contamination, or from leachate (water that has percolated through and is leaking from a location) from landfills or old dumps that have not been properly closed. High levels of ammonia can be toxic to invertebrates and fish, and contribute to nutrient loading by supplying excess available nitrogen.

In the above graph, the only sampling site that appears to consistently fall within standards is Bill Sadwoski Park. Matheson Hammock appears consistenly to fall out of range, while the Coral Gables Waterway spikes at the the highest level of 0.74mg/L. This spike could be a result of an event such as a major rainfall, the opening of flood gates, etc., or be due to sampling inconsistencies. The levels of NH4 in the canals are considerably higher than those observed in Biscayne Bay. Fortunately for the Bay, the concentrations of NH4 drop to more acceptable upon mixing with Bay waters. However, more research is needed to define acceptable levels of nutrients concentrations for a near shore estuarine mixing zone.

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Nitrate cannot be measured directly; a chemical reaction is performed to convert the nitrate to nitrite. However, to avoid confusion test results are expressed as combined nitrate + nitrite nitrogen, which is often abbreviated as (NOx-N). Phew, that's a mouthful.

The Biscayne Bay ecosystem naturally exists on very low levels of nitrogen and phosphorous and is vulnerable to excess nutrient loading. In order to prevent degradation of water quality in Biscayne Bay, concentrations of nitrate-nitrite should not exceed 0.01mg/L. Unfortunately, nitrate-nitrite levels found in tributaries feeding the Bay frequently exceed this standard, particularly in the south Miami-Dade, where canals (such as the Mowry and Princeton canals, whose averages are hundreds of times greater) receive runoff from the agricultural lands typical in this area. Fortunately for the Bay, the concentrations of nitrate-nitrite drop to more acceptable upon mixing with Bay waters. However, more research is needed to define acceptable levels of nutrients concentrations for a near shore estuarine mixing zone

Sources of nitrates include wastewater treatment plants, runoff from fertilized lawns and cropland, failing septic systems, runoff from animal manure storage areas, and industrial discharges that contain corrosion inhibitors.

With this data set, the only waterway that consistently fell within desired limits was Matheson Hammock. Matheson Hammock may have high ammonia rates due to the large amount of decomposing plant material around the site, but low nitrate-nitrite levels due to it's proximity to Biscayne Bay (perhaps the salinity of the water at this site prevents bacterial decomposition in nitrate, in addition to high levels of flushing). Four different sites show a spike in N+N levels in the sampling event on 8/14/2004, while Mahi canal consistently showed nutrient levels higher than the other sampling sites.. Additionally, there appears to be a trend towards rising nutrient levels for nearly all sites over this sampling period, however statistical analysis needs to be done to determine whether these observations are significant.

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Dissolved Organic Carbon (DOC) is a measure of the amount of dissolved organic material (carbon that passes through a 0.45 micron filter) present in a waterbody. DOC is produced from the decay of plankton, grazing by zooplankton, the decomposition of leaf litter, precipitation, and leaching from soils. DOC is of interest to ecologists as it can help chacterize the physical, chemical, and biological properties of water. For instance, high DOC can protect microorganisms from UVB radiation and depress primary productivity by afffecting the depth light penetrates through the water column (euphotic zone).

DOC may even affect the amount of toxic metals in an ecosystem. In the Everglades, current research indicates high levels of DOC (typically found in a wetland ecosystem due) may reduce levels of mercury in the ecosystem that can enter the bodies of wildlife, by binding with mercury and reducing its reactivity and availability. Read more about mercury and DOC in the Everglades from the USGS...

DOC can be influenced by human activities on a local and global scale. Activities such as deforestation, development, or land use can alter the amount of DOC entering into a waterbody by changing leaf litter decomposition or erosion rates, while pollutants entering the atmosphere can affect the amount of DOC entering the waterbody through precipitation and chemically reacting with DOC. While research is ongoing in this subject, current research indicates that these activities reduce the amount of DOC remaining in the waterbody.