Aidity | Alkalinity | Ammonia | BOD | CBOD | COD | Conductivity | Dissolved Oxygen | Fecal Coliform | Hardness | Metals | Nitrate | TKN | Organic Nitrogen | Nitrogen | Nitrogen as Ammonia | Phosphorus | pH | Total Solids | Temperature | Turbidity Acidity
Acidity of water is its quantitative capacity to react with a strong base to a designated pH. Acidity is a measure of an aggregate property of water and can be interpreted in terms of specific substances only when the chemical composition of the sample is known (19th Edition, Standard Methods, 1995) Alkalinity
The Alkalinity or the buffering capacity of a stream refers to how well it can neutralize acidic pollution and resist changes in pH. Alkalinity measures the amount of alkaline compounds in the water, such as carbonates, bicarbonates and hydroxides. These compounds are natural buffers that can remove excess hydrogen (H+) ions (1991, Streamkeeper's Field Guide: Watershed Inventory and Stream Monitoring Methods) . BOD
The Biological Oxygen Demand (BOD) is the amount of oxygen consumed by bacteria in the decomposition of organic material. It also includes the oxygen required for the oxidation of various chemical in the water, such as sulfides, ferrous iron and ammonia. While a dissolved oxygen test tells you how much oxygen is available, a BOD test tells you how much oxygen is being consumed. BOD is determined by measuring the dissolved oxygen level in a freshly collected sample and comparing it to the dissolved oxygen level in a sample that was collected at the same time but incubated under specific conditions for a certain number of days. The difference in the oxygen readings between the two samples in the BOD is recorded in units of mg/L. Unpolluted, natural waters should have a BOD of 5 mg/L or less. Raw sewage may have BOD levels ranging from 150 – 300 mg/L (1991, Streamkeeper's Field Guide: Watershed Inventory and Stream Monitoring Methods) .
Conductivity is a measure of how well water can pass an electrical current. It is an indirect measure of the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, phosphate, sodium, magnesium, calcium, iron and aluminum. The presence of these substances increases the conductivity of a body of water. Organic substances like oil, alcohol, and sugar do not conduct electricity very well, and thus have a low conductivity in water. Inorganic dissolved solids are essential ingredients for aquatic life. They regulate the flow of water in and out of organisms’ cells and are building blocks of the molecules necessary for life. A high concentration of dissolved solids, however, can cause water balance problems for aquatic organisms and decrease dissolved oxygen levels (1991, Streamkeeper's Field Guide: Watershed Inventory and Stream Monitoring Methods) . Dissolved Oxygen
The amount of Dissolved Oxygen (DO) in water is expressed as a concentration. A concentration is the amount of in weight of a particular substance per a given volume of liquid. The DO concentration in a stream is the mass of the oxygen gas present, in milligrams per liter of water. Milligrams per liter (mg/L) can also be expressed as parts per million (ppm). The concentration of dissolved oxygen in a stream is affected by many factors: • Temperature: Oxygen is more easily dissolved in cold water. • Flow: Oxygen concentrations vary with the volume and velocity of water flowing in a stream. Faster flowing white water areas tend to be more oxygen rich because more oxygen enters the water from the atmosphere in those areas than in slower, stagnant areas. • Aquatic Plants: The presence of aquatic plants in a stream affects the dissolved oxygen concentration. Green plants release oxygen into the water during photosynthesis. Photosynthesis occurs during the day when the sun is out and ceases at night. Thus in streams with significant populations of algae and other aquatic plants, the dissolved oxygen...