Nutrients - Total Nitrogen and Total Phosphorus:

Definition and importance: Nitrogen and phosphorus are elements required in large amounts (macronutrients) by plants and animals to synthesize proteins, nucleic acids, and phospholipids. Total nitrogen is the sum of different forms of nitrogen found naturally in water bodies, including nitrate, nitrite and ammonia, while total phosphorus includes both, ortho-phosphate (the chemically active dissolved form of phosphorus used directly by plants) and the phosphorus from plants and animals’ fragments suspended in the water.

Soil and rocks are the primary natural sources of phosphorus, usually in the form of phosphates. Natural nitrogen sources include leaves and other organic debris from terrestrial vegetation. However, human activities such as wastewater treatment plants, runoff from farmland or fertilized lawns, failing septic systems, runoff from animal manure and storage areas, and industrial discharges have increased the amounts of nutrients going into natural aquatic ecosystems.

Elevated concentrations of nutrients, but especially phosphorus (it is usually the limiting nutrient) can lead to an excessive growth of algae and aquatic plants. In extreme conditions, it causes eutrophication, once large densities of algae can decrease the penetration of sunlight through the water, preventing photosynthesis by submerged plants. In addition, the death and decay of algae can lead to decreased concentrations of dissolved oxygen. These changes can affect the diversity of plants, animals, and other aquatic organisms, and interfere with human uses of the water.

Method: The analyses include chemical digestion followed by colorimetric or spectrophotometric analyses. Here, the total concentrations are presented in milligrams (TN) and micrograms (TP, milligram divided per 1000) per liter of water.