Earth's Water: Surface Water and Groundwater

• Water makes up 71% of Earth's surface and is essential for all organisms.

• Water shapes the earth's surface, moderates climate, dilutes pollutants, and is vital for global health, security, economics, and the well-being of women and children.

• Water is considered cheap.

• Earth contains 326 quintillion gallons of water; Only 0.024% of it is available freshwater.

• Oceans hold 97.4% of the Earth's water volume, which is unsuitable for drinking, irrigation, or industrial use.

• Surface runoff is precipitation that doesn't infiltrate the ground or return to the atmosphere via evaporation.

• A watershed/drainage basin is a region where water drains into a stream, lake, or wetland.

• Groundwater is water that has infiltrated the ground and percolates through soil and rock voids.

• Aquifers are porous, water-saturated layers of sand, gravel, or bedrock through which groundwater flows.

• Confined aquifers are located between impermeable rock or clay layers.

• Unconfined aquifers are directly connected to the surface, recharged by rainfall, and able to rise and fall.

• A recharge area is land where water percolates to replenish aquifers.

• Agriculture is the largest consumer of water; Irrigation has the largest increase in water withdrawal over the last 100+ years.

Freshwater in the U.S.

• The Eastern U.S. has ample precipitation, while the West does not.
• In the East, freshwater is used for energy production, cooling, and manufacturing.
• In the West, freshwater is primarily used for irrigation.

Ways to Increase Freshwater Supplies

• Building dams and reservoirs
• Bringing in surface water from another area through tunnels, aqueducts, and underground pipes can cause environmental problems.
• The Aral Sea water transfer disaster led to increased salinity levels and extinction of native fish species due to climate change.
• Converting saltwater to freshwater (desalination)
• Withdraw groundwater year-round without evaporation loss, making it less expensive than surface water systems.
• Groundwater usage can lead to water table lowering, aquifer depletion/subsidence, and saltwater intrusion.
• Chemical contamination can occur.
• Importing food reduces water use, and wasting less water to grow food can be achieved through methods like gravity flow, drip irrigation, and center pivot.
• Desalinization involves two methods of salt removal but is expensive and produces wastewater.
• Reverse osmosis is used in desalinization.
• LEPA (Low Energy Precision Application) irrigation is a method to conserve water.
• Xeriscaping involves using vegetation adapted to dry climates, reducing water use by 30-85%.
• Gray water (from bathroom sinks, showers, tubs, and washing machines) can be used for irrigating lawns and nonedible plants.

Water Quality Tests

• Physical tests assess turbidity, temperature, and flow rate.
• Chemical tests measure pH and dissolved oxygen (DO).
• Biological tests analyze coliform bacteria and macroinvertebrates.
• Biological Oxygen Demand (B.O.D.) is also measured.

Floodplains & Wetlands

• Floodplains are productive wetlands that provide flood and erosion control, maintain water and soil quality, and recharge groundwater.
• Wetlands are important ecosystems.

Eutrophication

• Eutrophication is the natural nutrient enrichment of lakes via nitrogen, phosphorus, and potassium (N, P, K).
• Algae blooms form and block sunlight.
• DO levels drop due to increasing aerobic bacteria.
• Eutrophic lakes are nutrient-rich with murky water and high life diversity.
• Oligotrophic lakes are nutrient-poor with clear, cold water and low life diversity.
• Cultural eutrophication is nutrient enrichment due to human activities with inputs from farms, sewage plants, and fertilizer.
• Combat cultural eutrophication through wastewater treatment, limiting fertilizer use, banning certain chemicals, and soil conservation.

Water Pollution

• Water pollution is any chemical, biological, or physical change in water quality that harms living organisms or makes water unsuitable for desired uses.
• Pollutants include infectious agents, heat, plant nutrients, sediment, organic/inorganic chemicals, radioactive materials, and oxygen-demanding wastes.
• Non-point sources of pollution cannot be traced to a single discharge site (runoff of chemicals, agricultural runoff, car exhaust, acid deposition from mining).
• Point sources discharge pollutants at specific locations through pipes, ditches, or sewers (factories, sewage treatment plants, oil tankers).
• Chemical analysis: Dissolved oxygen (DO), nitrates, pH.
• Physical analysis: Temperature, turbidity, stream flow.
• Biological analysis: Indicator species (coliform bacteria).
• Coliforms are human intestinal bacteria found in mammals but can thrive in soil and water and may be of fecal/non-fecal origin.
• Escherichia and Enterococci are examples of coliforms.
• Fecal coliforms are a specific group of intestinal bacteria that grow at elevated temperatures and are associated with the fecal material of warm-blooded animals.
• Escherichia coli is an example of fecal coliform.

Sources of Fecal Contamination

• Wildlife
• Sewage via leaky septic systems, "straight pipes", and poorly designed/maintained sanitary sewers/wastewater treatment plants
• Agricultural waste via "direct deposit" from farm animals (lack of stream-side fencing), improper manure application, and poorly constructed/maintained waste storage.
• Human uses of surface water (irrigation, drinking, eating, recreation) are pathways for disease.
• Dissolved Oxygen (DO) is essential for healthy lakes and rivers.
• Biological Oxygen Demand (BOD) is the amount of dissolved oxygen needed by aerobic decomposers to break down organic materials in water over 5 days at 20°C.

Pollution of Freshwater Rivers/Streams

• River/streams are very resilient due to bacterial decay, moving water, and dilution.
• Pollution occurs from the release of chemicals by industry, fish kills, nonpoint runoff of pesticides/nutrients, malfunctioning sewage treatment plants, and drinking water contamination.
• Resilience depends on volume, flow rate, temperature, and pH level.

Pollution of Freshwater Lakes

• Lake pollution can be more problematic than river pollution because lake water is not moving.
• Lake pollution is affected by stratified layers, little flow, small volumes, and vulnerability to contamination (toxic chemicals, pesticides, mercury).
• Eutrophication is the natural nutrient enrichment of lakes.
• Oligotrophic Lake (nutrient-poor).
• Eutrophic Lake (nutrient-rich).
• Cultural eutrophication is added enrichment due to human activities.
• Wastewater treatment, limit fertilizer use, soil conservation, ban certain chemical agents, stop farm runoff needed.

Ocean Pollution

• Oceans are the ultimate sinks for waste (dilute, disperse, degrade).
• Ocean pollution can impact coastal areas, wetlands, estuaries, coral reefs, and swamps.
• Hypoxia is very low oxygen.
• Anoxia is zero oxygen (parts of the Gulf of Mexico).
• Harmful Algal Blooms (red tide, brown tide, rust tide).

Sludge Digestion

• Sewage sludge is a mixture of toxic chemicals, infectious agents, and settled solids removed from wastewater.
• Dredge spoils are materials, often laden with toxic metals, scraped from the bottoms of harbors and rivers.
• Pollution of groundwater with nitrogen leads to blue baby syndrome.
• Other contaminants: 1,4-dioxane, PFAS (PFOS & PFOA).

Wastewater Treatment

• Wastewater Treatment Objectives: Take human and industrial liquid wastes and make them safe enough (from the public health perspective) to return to the aquatic or terrestrial environment.
• Sewage/wastewater is composed of domestic used water/toilet wastes, rainwater, industrial effluent, and livestock wastes.
• Goal:Good microbes degrade organic compounds (and elimination of pathogens)
• Sewage Treatment
• Primary Treatment (Physical Process): Removal of large objects using grates/screens, settling to remove suspended solids (primary sludge), flocculating chemicals added to enhance sedimentation.
• Secondary Treatment (Biological Process): Lower BOD (Biological Oxygen Demand), aeration to stimulate aerobic degradation.
• Advanced Treatment (Physiochemical Process): Reverse osmosis, filtration, chlorination, UV or ozone.
• Trickling Filter Reactor: Sewage is sprayed over a bed of rocks/molded plastic where a slimy, gelatinous film of aerobic microorganisms grows on the rocks’ surfaces to remove about 80-85% of the BOD from sewage.
• Feces compacted used as fertilizers
• Methane is produced from these huge barrels and it creates electricity
• Methana runs turbines
• Methane generates heat which boils water and creates water vapor
• Wastewater bioreactors, wastewater gardens.

Oil Pollution

• Oil is released by normal operation of offshore wells, ashing tankers and releasing oily water, pipeline/storage line leaks, and activities on land (waste oil dumped, spilled, or leaked).

Cleaning Up Oil Spills

• Chemical: Coagulating agents clump for easier pickup, or surfactant agents disperse.
• Mechanical: Floats trap the oil/booms, skimmer boats gather oil and transfer barges, absorbent pads soak up oil.
• Bacteria- some species ‘eat’ oils
• Winds and waves will disperse oil
• Fire: burns off oil
• Water: spray beaches to move oil into collectible pools
• Subsidence occurs when water is pulled so fast from the ground that the ground collapses.

Dams

• Dams provide irrigation water above and below, provides drinking water, and reduces downstream flooding.
• Dams also have risks of failure, disrupt fish migration, and large water loss through evaporation.