Glossary

Ammonia

Ammonia is a compound composed of nitrogen and hydrogen (NH3) that is necessary for many biological processes, but can be harmful to humans and the environment in high concentrations. It is produced naturally by bacteria in soil and is present in plants and animals.  Therefore, ammonia in the environment can come from leaching of decaying plants and animals and from animal waste (including human waste).  It is also produced by humans and used widely in fertilizers, plastics, and explosives among other things.

Anoxia

Anoxic water is water that lacks oxygen.  Causes of oxygen depletion include lack of water circulation and excess nutrients in the water column causing excessive phytoplankton blooms that use up oxygen when they start to decay.

Chlorophyll

Chlorophyll is the green pigment used in the process of photosynthesis in plants (including algae) and some bacteria.  Chlorophyll is measured in the water column to help determine how much algae and bacteria are present, indicating when there are large numbers, or blooms, of these organisms, which may in turn lead to low dissolved oxygen.

Density

The density of water is defined as its mass or weight per unit volume.  The density of water can change with changes in temperature and salinity. This is an important parameter to monitor when looking at stratification of the water column, which is usually caused by density differences between two water masses.

Dissolved Oxygen

Dissolved Oxygen is amount of oxygen gas present in the water column.  Oxygen is present in the water column from the atmosphere and generated by phytoplankton through the process of photosynthesis.  Oxygen is required by all organisms, even those living in the water.

Enterococci

Enterococci are a genus of bacteria commonly found in the digestive tracts humans and other warm-blooded animals.  Enterococci concentrations are used as indicators of the potential health risk for individuals exposed to water, due to the presence of pathogens from untreated wastewater.  It is thought that presence of Enterococci, rather than fecal coliform, is a better indicator of the presence of pathogens in the water column.

Fecal Coliform

Fecal coliform are a type of bacteria that are commonly found in the digestive tracts humans and other warm- and cold-blooded animals.  Fecal coliform concentrations are used as indicators of the potential health risk for individuals exposed to water, due to the presence of pathogens from untreated wastewater.

Hypoxia

Hypoxia is a term used to describe low dissolved oxygen conditions in the water column.  Hypoxic conditions are commonly defined as 3 mg/L or less.  Causes of oxygen depletion include lack of water circulation and excess nutrients in the water column causing excessive phytoplankton blooms that use up oxygen when they start to decay.

Nitrate

Nitrate is a compound composed of a nitrogen atom and three oxygen atoms (NO3-).  This compound is classified as ion since it has an overall negative charge.  Nitrate is a naturally occurring and is formed as a breakdown product of animal or human waste, more specially, nitrifying bacteria oxidize nitrite to form nitrate.  Nitrate is commonly used as a fertilizer, so it can be present in the water column in high concentrations from agricultural runoff.

Nitrite

Nitrite is a compound composed of a nitrogen atom and two oxygen atoms (NO2-).  This compound is classified as ion since it has an overall negative charge.  Nitrite is a naturally occurring and is formed as a breakdown product of animal or human waste.  More specially, nitrifying bacteria oxidize ammonia to form nitrite.

Orthophosphate

Orthophosphate is a compound composed of one phosphorus atom and four oxygen atoms (PO4).  It is a naturally occurring form of phosphorus.  Phosphorus is a building block of life and plants need it to grow and the orthophosphate form of phosphorus is the form most biologically available to organisms.  If excess phosphorus is present in the water column, algal blooms may occur potentially leading to conditions of low dissolved oxygen.

pH

pH is a measure of the acidity or alkalinity (basicity) of a liquid solution.  This is measured using a pH scale which ranges from 0 to 14.  This scale is based on the concentration of hydronium ions (H3O+) in a solution.  The pH of a solution of pure water is 7, which is considered neutral.  Anything below 7 is acidic and anything above 7 is basic or alkaline. Most aquatic environments (streams, lakes, rivers, estuaries) range in pH from 6 to 8 and anything out of that range may cause stress to aquatic organisms.  Some organisms are more susceptible to changes in pH and the young of most species are more sensitive than older plants and animals.

Photic Zone

The photic zone is the depth in the water column where sufficient amount of light from sun is able to penetrate and support photosynthesis.

Photosynthesis

Photosynthesis is the process in which plants, phytoplankton and algae use the energy from the sun (i.e. sunlight) to convert carbon dioxide (CO2) and water into oxygen (O2) and sugar, which the plants, phytoplankton and algae use as food.  The chemical equation used to express this process is:
6 CO2 (carbon dioxide)
+ 6 H2O (water)
à(with sunlight)à C6H12O6 (sugar) + 6 O2 (oxygen).

Photosynthetically Active Radiation (PAR)

Photosynthetically Active Radiation (PAR) is the amount of light available for photosynthesis, which is light in the 400 to 700 nanometer wavelength range. PAR changes seasonally and varies depending on the latitude and time of day.

Phytoplankton

Phytoplankton are small organisms found in the water column that use sunlight and carbon dioxide to make sugars that they use as food, the process which is commonly called photosynthesis.  These organisms are the base of the food chain in waters of the world.

Salinity

Salintiy is the concentration of salt in water.  Freshwater (rivers, streams, lakes) usually has a salinity of less than 0.5 ppt, whereas ocean water has an average salinity of 35 ppt and in estuaries, where fresh river water meets salty ocean water, salinity can range anywhere between these concentrations.  Narragansett Bay is an estuary, with freshwater from rivers mixing with the salt water of Rhode Island Sound.  Certain organisms are adapted to live only within a certain salinity range and some are designed to be able to be in saltwater as well as freshwater.

Secchi Disk

A Secchi disk is a circle of usually metal.  They come in various sizes, but the standard is 8 inches in diameter.  The disk is separated into four sections alternating in color between black and white.  From a dock or boat, the disk is lowered into the water column to the point where the disk is no longer visible.  The disk is then raised to the point where the disk can first be seen and this depth is recorded.  This depth represents the water clarity of the water column and is very valuable information when the data is recorded on a regular basis and can be compared throughout the year.

Silicate

Silicate is a mineral compound composed of four hydrogen atoms, one silicon atom and four oxygen atoms (H4SiO4).  Silicate is a very important compound for a specific type of phytoplankton called diatoms.  Diatoms use silicate that is dissolved in the water column to construct a protective covering on the outside of their bodies.

Stratification

Stratification of the water column is when the water column is no longer mixed and is separated into two distinct water bodies with different properties.  Stratification is usually caused by differences in temperature, salinity or density.  Prolonged periods of stratification can be detrimental to organisms, since it prevents bottom waters from replenishing the dissolved oxygen concentrations from the surface.

Temperature

The temperature is the physical measure of the amount of heat energy present in the water column.  Temperature is measured with a thermometer.  The temperature is an important parameter to measure for many reasons.  First, most organisms are very sensitive to temperature and can survive in a very narrow temperature range.  Secondly, the temperature of the water limits the amount of dissolved oxygen water can hold.  High temperature water can only hold a limited amount of dissolved oxygen, while colder water can hold much more. Finally, temperature is important because differences in temperature in the water column can lead to stratification.

Total Suspended Solids (TSS)

Total Suspended Solids (TSS) is the amount of particles suspended in the water column and can include a wide variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage. High concentrations of suspended solids can cause many problems for stream health and aquatic life and can block light from reaching submerged vegetation.

Turbidity

Turbidity is the cloudiness or opacity in the appearance of water caused by solids, particles and other pollutants. Turbidity measurement provides an indication of the clarity of water and water quality.

Water Quality Sonde

Water Quality Sondes are instruments used to take measurements of various water quality parameters.  The NBC uses YSI sondes that measure temperature, salinity, dissolved oxygen, pH, chlorophyll and turbidity simultaneously.  These instruments look like a big tube with sensors on one end and can be deployed in the water for many days.  They collect measurements of these parameters at set time intervals and store the data within the instrument or in a separate data logger device.  These instruments are helpful for spot sampling and continuous monitoring of water quality.