Unit Three

“Fresh Water: Rivers, Lakes, & Wetlands”

Freshwater Systems

• Freshwater is categorized by whether it is flowing or still.

• Freshwater is also categorized by whether it is at the surface (surface water) or below the surface (groundwater).

• Most freshwater discussed in the following slides is surface water. However, especially in the state of Florida, the presence of groundwater should not be understated. Why?

Freshwater Systems cont’d

– Surface freshwater can be subdivided as follows:

– Flowing StillStream PondRiver Lake

SwampMarshBog

Freshwater Systems cont’d

• Streams, Creeks, or Brooks are small channels that carry water. The water in these structures flows.

Freshwater Systems cont’d

• As a river ages, it develops Meanders (twists and turns). The Kissimmee River prior to dredging in the 1960’s was a good example of an “old” river.

Freshwater Systems cont’d

• Rivers are bodies of freshwater that flow in a generally well-defined path, and eventually release their freshwater contents into an ocean

• Some terms associated with rivers– Mouth: where a river meets and ocean– Watershed: area of land drained by a river and all its

tributaries– Tributary: small river flowing into a larger one– Floodplain: areas on either side of a river that are

flooded periodically

Freshwater Systems cont’d

• Wetland is a generic term that describes a body of freshwater that is still and contains aquatic vegetation.

• It is different from another type of still freshwater known as a pond/lake. Ponds/lakes do not have emergent aquatic vegetation throughout.

Florida Swamp

Florida Marsh

Lake Okeechobee

Freshwater Systems cont’d

• Wetlands are categorized as one of the following:– A Swamp is a wooded area (trees) that has standing

water for at least a few months per year; common in Florida

– A Marsh is an area that has standing water for at least a few months per year and also has reedy/grassy vegetation that emerges from the water

– Bogs are ponds thoroughly covered with thick floating mats of vegetation

Freshwater Systems cont’d

• Ponds/Lakes are usually deeper than marshes, swamps, and bogs, and they usually have at least some water present at all times.

• Ponds/Lakes are divided into zones:– Littoral Zone – edge of pond/lake where vegetation is

found– Limnetic Zone – the surface water where light

penetrates– Profundal Zone – the depth of water where sunlight

does not reach– Benthic Zone – the bottom of the pond/lake

Pond/Lake Zones

Freshwater Systems cont’d

• Freshwater that moves below the surface is groundwater.

• Groundwater plays an important role in the Hydrologic Cycle. Why?

• 1/5 of the Earth’s freshwater supply comes from groundwater, and groundwater is found within an aquifer.

Freshwater Systems cont’d

• The Floridan Aquifer is the freshwater supply for the state of Florida

• Surface water can percolate through the soil horizons and subsequently be absorbed into the Limestone that composes the Floridan Aquifer.

Freshwater Systems cont’d

• Eventually the water contained in the limestone caverns of the Floridan Aquifer makes its way back up to the surface in one of three ways:– 1. Natural spring (vertical opening from

aquifer to surface)– 2. Artificial well (requires mechanical pumps)– 3. Artesian well (once dug, flows naturally)

Floridan Aquifer

Freshwater Systems cont’d

• It is important to understand freshwater is not distributed equally around the globe. (map on page 260)

• The above fact reinforces the idea from Unit One: resources are not distributed equitably throughout the world.

• Even though one may live where there is an abundance of water, one may have access to very little of it. Why?

How We Use Water

• There are two types of freshwater:– Consumptive - water that is removed from

aquifer or surface water and is not returned.• Example industrial use

– Nonconsumptive - water that is temporarily removed from aquifer or surface water, or is not removed at all.

• Example hydroelectric dams

How We Use Water cont’d

• Most human-related use of water is consumptive. Some examples are as follows:– 1. agriculture– 2. industry– 3. residential– 4. commercial

How We Use Water cont’d

• Humans are reducing the groundwater supply more quickly than it can be replenished.

• It takes longer for water to percolate through the soil horizons and eventually be deposited into an aquifer than it takes for humans to retrieve it.

• Sinkholes are the result of depleted aquifers; Lake May in Winter Park, FL

Lake May Sinkhole, 1981

How We Use Water cont’d

• The prognosis for surface water is no less bleak.• Humans divert surface water for a variety of

reasons such as:– 1. prevent flooding– 2. irrigation of fields– 3. water supply for populated areas

• Surface water diversion has many negative ecological effects– Example Dams alter hydrology of river

ecosystems

How We Use Water cont’d

• Reoccurring theme: Humans are just a part of the biosphere yet we have a large impact on the function of it. (the impact is usually negative)

• Recall from Unit One: only finite amount of water in the biosphere as is seen in the Hydrologic Cycle.

• The key is sustainability!

Solutions to Freshwater Depletion

• 1. Desalinization - taking salt out of ocean water then preparing it for distribution

• 2. Adopting efficient irrigation methods in reference to agriculture

• 3. Conserve water in urban areas via:• Watering lawns two to three times per week• Turn off water when not using it• Maintain leek-free faucets

Freshwater Pollution and Its Control

• Pollution – matter or energy released into the environment that causes undesirable impacts on the health of all species.

• Two Categories:– Point Source – can be traced back to a

discrete location– Nonpoint Source - cannot be traced back to a

discrete location

Freshwater Pollution and Its Control cont’d

• Additionally, pollution can be subdivided by substance in the water that is considered to be the pollutant:

• 1. Nutrients – fertilizer• 2. Pathogens – bacteria and viruses• 3. Toxic Chemicals – Mercury • 4. Sediment – result of mining or deforestation

Freshwater Pollution and Its Control cont’d

• Groundwater pollution is of serious concern.

• Many toxic chemicals as well as pathogens can become part of the groundwater system– Examples:

• 1. Pathogens from sludge removal • 2. Household chemicals

Freshwater Pollution and Its Control cont’d

• Water Quality is determined by analyzing several factors such as:– 1. pH - acidic or basic– 2. Turbidity – the amount of sediment in

water– 3. Nutrient content – Phosphorus and

Nitrogen– 4. Color – presence of Tannins cause the

water to have tea stained appearance – Florida streams and rivers

Freshwater Pollution and Its Control cont’d

• To protect the water supply in the USA, the federal government has instituted many regulations.– “Clean Water Act” of 1977 – water quality

requirements on businesses and industry

http://www.epa.gov/region5/water/cwa.htm

- EPA is in charge of enforcing the water regulations within the USA

Freshwater Pollution and Its Control cont’d

• Potable water, that is, drinking water, is put through a process before it is distributed to homes and businesses.– 1. Pumped from aquifer– 2. Aerated to release sulfur (rotten egg odor)– 3. Chlorine and Fluoride are added to reduce

pathogen potential and for benefits to teeth, respectively

Wastewater and Its Treatment

• Water Reclamation Facilities convert wastewater into water that is suitable for irrigation.

• There are several steps to cleaning up wastewater:– 1. Gritch Chamber – entry point of

wastewater where particulates removed – “sludge”

– 2. Clarifier – oils and grease removed

Wastewater and Its Treatment

– 3. Aeration – microbes consume organic matter

– 4. Secondary Clarifier - remaining oils and grease removed

– 5. Disinfection – addition of chlorine to kill any remaining pathogens

*** Water leaving plant looks clean and clear*** Good way to conserve water and reduce

pollution

Wastewater and Its Treatment

• The “sludge” that is a byproduct of the reclamation process is dehydrated by sending it through a belt press

• The resulting dehydrated sludge, now known as Biosolids, is then taken offsite to landfills, agricultural areas, or ranchland to be used a fertilizer

• Areas where this “fertilizer” is spread are tested for the presence of pollutants in the groundwater as a possible result of this addition at the surface

• http://www.youtube.com/watch?v=XDyj_bzoezg