WATER AND THE ENVIRONMENT - FINAL EXAM

How is Dissolved Oxygen Content (DOC) and Biochemical Oxygen Demand (BOD) used as indicators for water quality guidance?

amount of oxygen need to decompose organic matter is called Biochemical Oxygen demand. The measure of oxygen in the water is called dissolved Oxygen content. large amounts of organic and biological matter (contaminant) in the water requires lots of oxygen to decompose, which depletes the oxygen in the water causing what is called a dead zone. dissolved oxygen content can be used as an indicator of poor water quality because water with with high dissolved oxygen content implies less contaminants in the water.

What is acid mine drainage (AMD), and how is it caused?

it is the outflow of acid water from METAL MINES or COAL MINES. Metals are predominantly some form of SULFIDE METALS (Lead, gold) it is caused by SULFIDE RICH METALS dissolving into the water resulting in SULFURIC ACID and releasing HEAVY and TRACE METALS. * this process can be enhanced by bacterial action *

what is dissolved oxygen content?

measure of oxygen in the water.

summary of sources of contamination (first 3 are most important)

most important to know (mainly first two): category 1 - sources designed to discharge substances: *septic tanks. *injection wells. category 2 - sources designed to store, treat, and/or dispose of substances: *landfills. *waste tailing. * waste disposal site. category 3 - sources designed to retain substances during transport and transmission: *pipelines. less important to know: category 4 - sources discharging substances as a consequence of other planned activity: *pesticides. *fertilizers. *acid mine drainage. category 5 - sources providing conduits or inducing discharge through altered flow patterns: *production wells. *monitoring wells. *excavation. category 6 - naturally occurring sources whose discharge is created and/or exacerbated by human activity: *seawater intrusion. *GW - SW interaction.

are all trace metals harmful to humans?

no

How does each kind of contamination differ in their transport or spreading pattern with the groundwater flow?

APL: APL flows with the GW flow. it moves away from the contamination source in the direction of GW flow and it creates a plume in the aquifer as it gets farther away from the source. LNAPL: LNAPL flow on top of the water table and moves in the direction of GW flow. some of its dissolves in GW. DNAPL: DNAPL flows downward until it reached relatively impermeable rock and then it flows down the slope of the impermeable rock layer.

What is a contaminant (contamination)?

a contaminant is any physical, chemical, biological or radiological substance or matter in water. drinking water may reasonably be expected to contain at least small amounts of some contaminants. some contaminants may be harmful if consumed at certain levels in drinking water. *the presence of contaminants does not necessarily indicate that the water poses a health risk.

What is a dead zone, and how is it caused?

a dead zone is an area where fish are unable to live due to very little dissolved oxygen content as a result of high levels of contamination.

What are two different kinds of groundwater contamination based on their solubility?

a. Miscible water contamination (APL) b. Immiscible water contamination (NAPL)

Examples of AMD or ARD

abandoned mine in Ohio have cause acid mine drainage into many waterways. Some examples include the Cuyahoga river, the Tuscarawas river, the scioto river back in the 1980s COLORADO -20,000+ mines -1,300 miles of stream MONTANA -20,000+ mines -1,000 miles of stream ARIZONA -80,000+ mines -200 miles of streams

why is acid mine drainage especially harmful?

- it can occur INDEFINITELY - it will continue to cause harm long after mining has ended. * many mine may require water treatment for HUNDREDS TO THOUSANDS OF YEARS *

How does groundwater pumping affect the characteristics of contaminant transport? (know at least 3)

1) accelerates GW flow toward well. 2) captures contamination within cone of depression. 3) may reverse GW flow. 4) can draw contamination up hill. 5) spreads the contamination. 6) will cause saltwater intrusion.

What are 3-4 examples of technologies that can be used to remediate groundwater contamination?

1) bioremediation. 2) permeable reactive barrier. 3) chemical treatments. 4) thermal treatments. some other examples: 5) multiphase extraction. 7) phytoremediation.

How does the office of technology assessment (OTA) classify sources of groundwater contamination? (5 different ways) *Note; USEPA uses this classification criterion to allow permits for various needs of our society

1) by way of release. 2) by origin. 3) by chemical type. 4) by location. 5) by character.

What are the different drinking water standards laid out by USEPA?

1) maximum contaminant level (MCL). 2) maximum contaminant level goal (MCLG) 3) maximum residual disinfectant level (MRDL) 4) maximum residual disinfectant level goal (MRDLG)

3 examples of wastes.

1. chemical wastes (industrial). 2. radioactive (nuclear) wastes. -energy wastes. 3. agricultural wastes.

which contaminant is the most hard to remove from aquifers?

1. oil spills (can take decades to cleanup).

what are the most insidious/harmful contaminants in order from greatest smallest?

1. radioactive (nuclear) wastes. -hard 2 find suitable sites for storage of radioactive waste. 2. chemicals wastes (industrial) -oil spills. 3. sewage and wastewater -agricultural wastes.

USEPA: types of contaminants

1. radioactive contaminants. 2. Trace Metals - aluminum, arsenic, lead, zinc. 3. nutrients - nitrates (NO3), NH4, pesticides. 4. other inorganic species - common anions and cations 5. Organic Contaminants - most serious problems; hydrocarbons; solvents. 6. biological contaminants - bacteria, virus

what is a pollutant (pollution)?

A POLLUTANT is a harmful substance. POLLUTION is the introduction of harmful substances [pollutants] into the environment by human action or natural processes.

what is miscible water contamination (APL)? What characterizes it? What is an example of miscible water contamination?

Aqueous phase liquid (APL) contaminant. characteristics: It is able to dissolve in water. dissolved contamination travels with GW flow. contamination can be transported to water supply aquifers down flow. pumping will draw contamination into water supply. An example of this is salt water intrusion.

concerns and challenges related to hydraulic fracturing?

CONCERNS: 1) concern: that fracturing will fracture so much that it will contaminate the groundwater. (this is unlikely because fracturing occurs far (>4000feet) beneath aquifer) 2) concern: fracking causes earthquakes. >fracking is NOT causing most of the induced earthquakes!!! >RATHER wastewater disposal is the primary CAUSE of the recent increase in earthquakes in central US. > we are injecting wastewater even DEEPER than where the oil is being produced. this allows the fluids to migrate to deeper fault systems. CHALLENGES - The water cycle around hydraulic fracturing: 1. a lot of water is needed for the drilling operations. 2. a lot of the water undergoes chemical mixing during fracking process. once it mixes with various chemicals IT CANNOT BE RECYCLED --> this water is called PRODUCED WASTE WATER

what are the similarities and differences between contamination and pollution?

CONTAMINANTS are not necessarily HARMFUL substances, they are just any type of substance or matter found in water. POLLUTANTS on the other hand are HARMFUL substances. *however some contaminants can become harmful when the reach a certain concentrations.* CONTAMINATION is the introduction of any substance of some foreign origin into the environment/water. POLLUTION on the other hand, is the introduction of specifically HARMFUL substances into the environment/water. CONTAMINATION does not = POLLUTION. BUT POLLUTION does = CONTAMINATION.

What is a challenges associated with hydraulic fracturing in the past?

Challenges: >1990: it was known that low hydraulic conductivity Oil and Gas reserves existed BUT they could not be mined because of low hydraulic conductivity (not economical)

what is DNAPL? what characterizes it? give an example.

DNAPL stands for: dense non aqueous phase liquid, which means that it is denser than water. characteristics: sinks past water table. flows down the slope of an impermeable layer. contaminates deeper portions of aquifers. an example of DNAPL is a dense solvent like DRY CLEANING FLUID.

What are some examples of remediating AMD?

Dilution, filtering (V. expensive) CONSTRUCTED WETLANDS alkaline beds limestone channels other chemical engineering solutions (anhydrous ammonia, hydrogen peroxide, calcium oxide) the best method to treat AMD is prevention.

What is the history of hydraulic fracturing?

HISTORY OF HYDRAULIC FRACTURING: >The birth of fracking (in general) began in the 1860s during the CIVIL WAR. >(At this time fracking was LIMITED to shallow wells - Done out of necessity for the war - Not yet done for oil and gas extraction). >The birth of 'modern-day' hydraulic fracturing - to extract oil and gas - BEGAN in 1947. >On march 17, 1949, Halliburton conducted two commercial experiments to see if injecting fluids at a high pressure would produce MORE GAS or OIL. >The experiment was SUCCESSFUL. >(still not as deep - no horizontal drilling yet) ****MODERN DAY FRACKING DIDN'T BEGIN UNTIL THE 1990'S**** >George P. Mitchell created a new technique, which took hydraulic fracturing and combined it with horizontal drilling. >At first could only drill 500ft down. Over time we could drill deeper

What is hydraulic fracturing?

Hydraulic fracturing: is an OIL and GAS well 'development' that typically involves injecting water, sand, and chemicals UNDER HIGH PRESSURE into a low hydraulic conductivity formation using a well. This process is intended to CREATE NEW FRACTURES in the rock as well as INCREASE THE SIZE, EXTENT, AND CONNECTIVITY OF EXISTING FRACTURES.

what are extremely contaminated sites called?

superfund sites

What is hydraulic fracturing used for?

It is used to extract oil and gas from the deep within the earth.

What is the produced wastewater?

It is water that undergoes chemical mixing during the fracking process. due to the chemical mixing it can never be recycled. It is called produced wastewater because it is water we've turned into wastewater through the process of fracking.

Contamination classification: source and modes

surface water groundwater

water are two types of Immiscible water contamination (NAPL)?

LNAPL and DNAPL

what is LNAPL? what characterizes it? give an example.

LNAPL stand for: light non aqueous phase liquid, which means that it is less dense than water. Floats on water table. dissolves in GW. transported by GW. contaminates shallow aquifers. an example of a LNAPL is leaking gasoline.

what is POINT SOURCE CONTAMINATION? and give an example of it.

This is contamination that is located at a specific place. I they are easy to identify, monitor, and regulate. examples: leaking tanks, spills, landfills, tar pits.

what is Immiscible water contamination (NAPL)? What characterizes it? what is an example of immiscible water contamination?

Non-aqueous phase liquid (NAPL) contamination. characteristics: It is any liquid that does not dissolve in water - no mixing. an example of this is crude oil.

What is the difference between primary and secondary water standards?

PRIMARY standards are enforced by the EPA, but SECONDARY standards are not enforced by the EPA.

is Deepwater Horizon Blowout in the Gulf of Mexico an example of point source contamination or non-point source contamination?

Point source.

what are the biggest WATER contamination challenges of our society and why?

Sewage and wastewater is the biggest challenge (more than 80% of the world's wastewater flows back into the environment without being treated or reused, according to the UN). due to lack of infrastructure. another big challenge is fossil fuels (oil & gas) pollution.

Some things to note about hydraulic fracturing from the Ted Ed video shown in class...

The creation of hydraulic fracturing wells, starts out by creating a wellbore. This wellbore is created by VERTICAL DRILLING to about the DEPTH OF 2500-3000 METERS. This depth is the KICKOFF POINT where the process of HORIZONTAL DRILLING CAN BEGIN. The direction of the well turns 90˚ and EXTENDS HORIZONTALLY for about 1.5 KILOMETERS through the SHALE rock formation.

what is/are the challenges in identifying most of the contaminants?

The majority of contaminants are invisible: gases (CO2, CH4). Aqueous phase contaminant (SW & GW) - industrial released - farm releases. however trash and oil are visible.

what is NON-POINT SOURCE and give an example of it.

This is broad contamination diffuse over large areas. They are very difficult to identify and control. They are expensive to clean up. Hard to determine who exactly is responsible. example: agricultural chemical application (fertilizers/pesticides). Large scale mining.

What can be the challenges associated with the management of produced wastewater?

figuring out how to dispose of it in a way that its not polluting the environment.

which is true? contamination = pollution OR pollution = contamination

pollution = contamination

Why and how does AMD get harmful to our water and the environment?

resulting fluids may be highly toxic, and when mixed with groundwater, surface water and soil, may have harmful effects on humans, animals, aquatic life, and plants.

what does this mean?: contaminant ≠ pollutant, and contamination ≠ pollution BUT pollution = contamination

the Implication of this is that CONTAMINATION is A BROADER CONCEPT THAN POLLUTION, which involves introducing a substance of some foreign origin to the environment, but not necessarily of polluting components. POLLUTION is a more specific term, referring to the introduction of only one kind of substance (harmful) whereas, CONTAMINATION is an umbrella term, referring to the introduction of any kind of foreign substance.

What is biochemical oxygen demand?

the amount of oxygen required to decay a certain amount of organic matter.

What are the various contamination challenges of our society?

the biggest challenge is air pollution (90% of the worlds children are breathing toxic air). Climate change. (will affect everyone on planet earth).

summary of toxic metals

toxic metals when in high concentration include: -copper -aluminum -cadmium -arsenic -lead -mercury low pH (acidic enviro) enhances their mobility to pollute vast areas. These metals particularly the iron may coat the stream bottom with an orange-red colored slime called YELLOWBOY.