THE NITROGEN AND PHOSPHOROUS CYCLES
2. Atmospheric fixation - lightning.
3. Nitrification - ammonia (NH3) converted by nitrosomonas to nitrite (NO3). Nitrite converted by nitrobacteria into Nitrate. These processes lower dissolved oxygen and pH. What does this mean in terms of water quality testing?
4. Denitrification - release nitrogen from nitrates back to the atmosphere.
2. Runoff from feedlots and other areas where large numbers of domesticated animals are kept contains much nitrogen. This can be a significant problem that not only results in surface water contamination but also contamination of shallow aquifers.
3. Also, agricultural lands are fertilized and irrigated. Runoff
carrying nitrogen can be significant. As much as 75% of applied
synthetic fertilizers can leach down and pollute subsurface waters.
In cities, storm sewer systems are also a major source of nitrogen pollution.
In rural and suburban environments, septic tanks and similar small treatment
systems discharge nitrogen contamination directly to the subsurface soils.
Sources of Phosphorous in the Aquatic Environment
2. Birds - waste from sea birds, called guano, as a result of their food chains.
3. Red Clay (sediment)
4. Detrital breakdown of phosphorous in benthic sediments (internal loading); upwelling of deep ocean waters makes this source available to organisms in the water column.
5. 1 mg of organic phosphorous in a lakeís cycle will require about
130 mg. of oxygen to break it down to orthophosphate. Can cause anaerobic
About 20-30% from detergents
Eutrophication -Phosphorous is first limiting element. It is largely a freshwater problem in lakes and shallow water bodies. When phosphorous levels are above .05 ppm, excessive growth of algae can occur. Small changes in the phosphorous concentration can have dramatic effects.
Three categories of phosphorous:
Most trouble for freshwater aquatic systems
The kind used in fertilizer (soluble in water)
Contribute significantly to Eutrophication.
2. Condensed phosphates:
3. Organically bound phosphorous:
Results in nuisance algae blooms and potentially fish kills.
Algae blooms can make drinking water smell and taste like petroleum and/or fish.
2. Urban runoff contaminated by fertilizer.
2. Setting phosphorous limit of 1 mg/L in NPDES permits.
3. Buffer zones.
4. No more chem-lawn.