GEO 101 Environmental Geology

Class notes for October 10, 2007

   

Selected Water Pollutants
   Oxygen Demanding Waste     -Biochemical Oxygen Demand -- When organic rich waste uses up oxygen needed for aquatic life.

 
  

Diseases resulting from contamination by Fecal matter: 

Pathogenic Organisms
      -Fecal Coliform Bacteria -- found in fecal matter. Used to measure sewage presence in water. Not dangerous for the most part. However, there are strains that are deadly. 
      -Cryptosporidium -- Bacteria, can be lethal. Infested Milwaukee water supply at one point.
       -Giardia -- Found in beaver, deer and other animals. Why you shouldn't drink from wild streams without filtering water first.
                       
                             -Cryptosporidiosis:  caused by cryptosporidium.  Symptoms:  watery diarrhea and abdominal cramping: No treatment, 155 cases in NY in 2006
                             -Giardisis caused by Giardia. Symptoms:  diarrhea, abdominal cramps, bloating and fatigue. Treatment antibiotics: 938 cases in NY 2006
                            Those at Risk:
                            -People residing in institutional settings
                            -people in day care centers
                            -foreign travelers
                            -Individuals who drink improperly treated surface water
                            -Homosexual or bisexual males.
        

                           Flow of Pollutants

     Ground water  flows along the gradient in the water table, taking a path that is perpendicular to the contours. Pollutants in the groundwater will flow in plumes along the same path.

 

-When a pollution source is introduced into the groundwater, the resulting plume will only affect areas down gradient from the source. Areas up gradient of the source, to the sides of the plume or below the plume will not be contaminated. Groundwater flows relatively slowly. On Long Island a typical rate of flow is about one foot per day near the water table, slower at greater depths. As the contaminant plume travels it becomes somewhat broader and more dilute as it slowly mixes with the surrounding cleaner water. Depending upon the original concentration of the plume and the distance the plume travels the contaminants may become so diluted that eventually the concentrations are lower than drinking water standards.


Pollution Sources for Groundwater
 
 

 

Overabundance of Nutrients such as nitrogen as nitrate or ammonium and phosphate -- can cause Eutrophication.


        -Anoxia -- When the overabundance of nutrients causes an alga bloom in the spring and early summer. Later in the summer these algae settle to the  bottom and bacteria feed on the algae which uses up the free oxygen in the bottom waters of the body of water.
        -Hypoxia -- When the algae bloom  and decay results in a low level of oxygen within the water body which will not sustain normal bottom dwellers or fish.

          The lack of oxygen causes the existing life, such as fish, crabs, lobsters, clams etc., within the water body to die.

This is happening in areas of the bottom of the Gulf of Mexico and Long Island Sound.

See links on algal blooms http://oceanservice.noaa.gov/topics/coasts/hab/welcome.html
 

  
        - Hazardous Chemicals (Toxic organic and Inorganic compounds).  Dry Cleaners dumping their used dry cleaning chemicals in the back of their establishments is still a major source on Long Island. 
        -Heavy Metals -- Lead, Mercury, Zinc, Cadmium
       - Radioactive Chemicals
       - Sediments -- In zones of high erosion, sediments can really clog up many streams and ponds. These sediments are often top soil which is rich in plant nutrients and pesticides. These contribute to eutrophication and poisoning of the aquatic life.
       -Thermal Pollution- Many industries use water to cool their equipment. They then dump this warm water back into it's source. This is pretty harmful to  the native life of the region, as it has generally evolved to survive in a particular range of temperatures.

Many of these issues are a strong concern on Long Island. Many groups have been formed that study and focus on them. For example, the Peconic Estuary in the eastern part of Long Island. The Long Island Groundwater Research Institute here at Stony Brook does detailed studies on the structure, movement, and contamination of groundwater in the Long Island region.

                           Flow of Pollutants 

     Ground water  flows along the gradient in the water table. Pollutants in the groundwater will flow in plumes along the same path.    


 

 - Factories and underground storage tanks are a source of groundwater pollutants. If a tank with a water soluble liquid leaks the liquid travels down to the water table. It then dissolves in the groundwater.  These pollutants flow as a plume along with the groundwater. They can pollute wells and surface water fed by the groundwater along the plume path.

 


 

  - If the liquid that leaks is less dense than water and insoluble in water, it floats on top of the groundwater table. If the liquid is highly volatile, for example gasoline, some of the liquid will evaporate, traveling upwards to the surface in the form of vapor fumes. All chemicals are somewhat soluble in water. The dissolved fraction will travel as a plume in the groundwater. . Liquids that are denser than water sink through the groundwater until they reach an aquitard. They then move slowly along the top of the aquitard along with the groundwater.

Cemeteries

Cemeteries are another source of pollution for groundwater. They are often located at the top of  hills, and are thus up gradient from the local groundwater  flow. Decomposing bodies within the cemetery release bacteria, breakdown products from decay and the chemicals used for embalming into the local groundwater supply.

 

If you were limited to 55 gallons of water per week, how would you use it?

Salt Water Intrusion

--Areas surrounded by the saltwater, such as Long Island, need to be concerned about contamination by sea water. Since the specific gravity of fresh water is less than that of salt water (1.0 vs. 1.025), fresh water floats on top of sea water, forming a fresh water lens.



     For For every foot of fresh water above the sea level, there are 40 feet of freshwater below sea level. Below the fresh water salt water saturates the aquifer. When you pump out fresh water rapidly, you lower the height of the freshwater in the aquifer forming a cone of depression. The salt water rises 40 feet for ever 1 foot of freshwater depression and forms a cone of ascension. Seawater may eventually enter a well that was once pumping fresh water, making it unusable.



     Areas like Great Neck and Montauk suffer from this phenomenon. In Montauk this especially a problem in the summer time , when the population increases greatly due to tourism and vacationers.

How Can We Protect Our Water From Hazardous Waste?

Minimize use of fertilizers, herbicides and pesticides to the greatest extent possible.

Never pour chemical products down the drain or on the ground.

Buy small quantities and use them up.

Prevent spills and leaks and clean up immediately if they occur

Share leftovers with friends and neighbors.

Store carefully. Seal tightly with labels intact.

Use safer alternatives whenever possible.

Bring up to 5 gallons of waste oil to local service station.

Report suspicious dumping activities to the police.

Bring hazardous waste to local hazardous waste site or save for local collection on special days.