ENST Midterm 2
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. What would you like to do?
What are the primary sources/reservoirs of drinking water
- Rain & Snow (collected and precipitated)
- Surface Water (rivers, lakes oceans)
- Groundwater (aquifers, water table)
- All together <1% of global water supply
What are the Pros of desalination?
Reduce strain on limited water sources (replenish habitats), increase water supply, improve water quality and sanitation, useful for agriculture and residents, we are in a water crisis, population will be increasing, demands will go up but supply will go down, ocean water is nearly limitless, more sustainable
What are the Cons of desalination?
Energy, money (very expensive), can hurt environment (heated water), loss of habitat, kill fish (impingement), alter water flow, scaling issue, brine waste sent to landfill
Under what circumstances (geographic, economic etc.) would a desalination plant be an ideal institution?
- If freshwater costs exceed desalination costs
- If the energy it requires runs on renewable resources
What are the three types of threats to drinking water
- 1)Source-related (groundwater contamination, logging/mining runoff)
- 2)Treatment-related (chlorine, fluoride)
- 3)Distribution-related (copper, lead in pipes)
How is drinking water monitored and/or regulated? What are the challenges associated with this?
- Regulated by EPA, water utilities notify public if contaminants are found above MCLs set by the Safe Drinking Water Act
- 1)Laboratory needs to know what specific chemicals to look for
- 2)Standard methods of analysis not available for unregulated pollutants
- 3)Economically impractical (even for large community water systems)
- 4)Social issue of large cleaning systems only available for certain class types
Whats bad about bottled water?
Regulated by Food and Drug Administration (not EPA) so not as stringent looking at bacteria/viruses, flavoring, plastic leeching, costs, TSS data. Private enterprises, hard to regulate.
What precipitates from hard water?
Ca and Mg
What do Dissolved Organics do in water?
Cause color, odor, and taste problems; need activated carbon filter to remove organics with high temp and adsorption filters
What were the "eras" of development in trying to control risk?
- Pre-1950s--Engineering-era: structures built large and strong
- 1950-70s--Behavioral-era: environment is �engineered�
- 1970-90s--Developmental-era: resources determine vulnerability
- 1990---Complexity-era: emphasizes mutual interactions between nature and society
What is the difference between hazard and risk?
- Hazard = Potential threat or danger to humans and their welfare
- Risk = Probability of hazard occurring or creating loss; hazard x exposure x fragility; probability, type/severity, size, certainty, distribution/timing
What are the methods of Risk Assessment?
Objective/Scientific and Subjective/Value-based
What is involved in Objective/Scientific Risk Assessment?
- a.Hazard identification- health threat?, qualitative chemical evaluation
- b.Dose-response analysis / Toxicity assessment- uses mathematical modeling or safety factor approach
- c.Exposure assessment- demographics at risk
- d.Risk characterization- uses likelihood / consequence charts
What is involved in Subjective/Value-based Risk Assessment?
- a.Who will bear the burden
- b.Risk philosophy (precautionary [business bears burden] v. free market [public])
- c.Risk reduction- both on nature and humans
What are some risk assessment case studies?
- Risk of Caulerpa seaweed case study- aquariums spreading the plant in the ocean
- Risk of Mono Lake and the CA Aqueduct
- Risk of Channel Islands and decimation of fisheries
What is the Risk Equation to Determine Risk?
- Acceptability Quotient = Benefit * (Cost/Risk)
- If AQ > 1, then acceptable risk
- Likelihood / Consequence Table
Name the 6 Federal Water Quality Regulations
- National Environmental Policy Act- environmental impact statements
- Clean Water Act- water pollution control, navigable waters only
- Endangered Species Act- threatened/endangered biodiversity [and habitats] (majority are marine species)
- Safe Drinking Water Act- EPA sets MCLs, protected human health, protected aesthetic water quality
- Resource Conservation and Recovery Act- hazardous waste management and disposal
- Superfund (CERCLA)- mitigation of abandoned or uncontrolled sites
What are Environmental Impact Statements regulated under?
What is NPDES?
National Pollutant Discharge Elimination System, authorized by the EPA under the CWA; permit program to control water pollution from point sources; industrial/municipal facilities must obtain permits to allow their discharges to go directly to surface waters; has significantly improved our water quality; EPA delegation to state agencies for implementation- e.g. State Water Resources Board, Regional Boards, Waste Discharge Requirements
What is Nitrogen Fixation?
Process of converting inorganic, molecular nitrogen (N2) in atmosphere to ammonia (NH3) or nitrate (NO3)
What are the three types of fixation?
- 1) Atmospheric fixation- lightning
- 2) Industrial fixation- pressure and heat, N-fixing crops (legumes), fertilizers, Haber-Bosch process to create NH3
- 3) Biological fixation- free-living and symbiotic bacteria (largest percentage of fixators) making NH3 and NH4 for organism consumption
Define and describe the source of molecular nitrogen (N2). What function does nitrogen serve in the ecosystem once fixed?
Triple bond N, inert, unusable for most organisms. Fixated nitrogen (nitrate or ammonia) in soil useable by plants/algae to grow (nucleic acids/amino acids)
How have humans impacted the nitrogen cycle? Why is this something we should be concerned with?
Development of intensive agriculture and industrial processes on massive scales, burning fossil fuels; nitrogen cycle off-balance
Define and describe the primary components of the nitrogen cycle. Discuss the primary organisms involved with this process. Where do these organisms live?
- Fixation- from N2 to nitrate or ammonia, done by symbiotic and free-living bacteria (cyanobacteria in marine ecosystems and on land in other organisms), industry, agriculture, and nature (lightning)
- Dinitrification- done by nitrifying bacteria
What would you like to do?
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