Unit 8 - Aquatic and Terrestrial Pollution
8.1 Sources of Pollution
- water pollution - point source & nonpoint source
* water quality standards set by EPA
* point source - pollution from a clearly identified single source
* ex. wastewater plants, paper/pulp mills, oil refineries, CAFOs, gas tanks, etc.
* industries required to get permission from state/EPA to release waste into water + have the plan to treat waste before release
* nonpoint source: pollution that cannot be traced back to a single source; comprised of multiple sources built up over time
* ex. fertilizers, insecticides, herbicides, runoff from precipitation, sediment from construction sites and croplands
* managed through business and landowner partnerships
8.2 Human Impacts on Ecosystem
- coral reefs → support 25 percent of marine species underwater
* affected by destructive fishing practices
* bottom trawling: crushes coral as nets scrape ocean floor
* marine debris: damages reefs and organisms that are dependent on them
* overfishing: removes fish and inhibits regulated algae growth
* cyanide fishing: poisons coral; done to catch large amounts of fish for commercial use easily - sedimentation → traps coral from sunlight → no photosynthesis → death of coral
* optimal: middle portion of range of tolerance; implies homeostasis and proper maintenance
* coral bleaching: releases symbiont resulting from heat (rising temperatures) → loss of food and color - dissolved oxygen: decreases as a result of algal blooms caused by runoff
* measured in ppm
* displayed in the oxygen sag curve → dissolved oxygen levels in relation to distance from the source
* clean zone: balance of oxygen and dissolved oxygen levels; biologically diverse species
* septic zone: very few species; dangerously low oxygen levels;
* recovery zone: demand is lower; dissolved oxygen increases
* increase in the distance from the source = increase in dissolved oxygen levels and decrease in biological oxygen demands - oil spills affects wildlife and ecosystems negatively
* impairs birds ability to fly by coating their feathers
* impairs temperature regulation and waterproofing of ocean mammals as their fur is saturated with oil
* can poison organisms from hydrocarbons
* alter food chains by killing organisms living at the bottom of the ocean
* damages fisheries financially and hinders their development
* decreases oxygen levels in water
* smother eggs/larvae of aquatic organisms - toxic metals found in drinking water → cancer, organ damage, neurological issues
* ex. mercury poisoning → methylmercury → neurological damage/birth defects
* includes lead arsenic cadmium mercury copper and chromium
* metals infiltrate groundwater reserves when released by miners in nearby water reserves
* plastic waste threatens wildlife in ocean
* blocks digestive system of organisms
* leads to entanglement/suffocation
* acclamation of microplastics → increased toxicity
8.3 Endocrine Disruptors
groups of different chemicals that interfere the process of hormones being used in the body
- cell signaling is disrupted by mimicking its structure or block the signal from reaching the receptor
- leads to reproductive abnormalities, birth defects, and neurological changes
- found in toxic waste from natural and synthetic processes
- can be accumulated and magnified in high-level organisms by eating prey with endocrine disruptors in body tissue
8.4 Human Impact on Wetlands & Mangroves
- wetlands: areas filled with mostly water on the surface during all or most of the year
* fluctuates in level and sanity from tidal influence or seasonal change
* can be mitigated through filtration
* plant roots take up excess nutrients from runoff for growth or decomposition
* controls flood by holding water
* recharges groundwater reserves during dry periods
* home to diverse habitats and filled with resources to thrive - mangroves provide shelter for animals & absorb great deal of CO2
* threatened by commercial development ad dam construction
* dam construction: reduces water flow and inhibits fish migration
* protected by the wetlands protection and restoration act
* overfishing → removing some essential fishes from the ecosystem
* impacts by CAFO pollutants (ie. waste)
8.5 Eutrophication
- algal blooms in water which occurs as a result of nutrient excess
* nutrient excess caused by agricultural and waste runoff
* also sourced from phosphorus in detergents
* ex. sewage, excess fertilizer, phosphate, nitrogen from animal manure
* washed into bodies of water by precipitation and irrigation
* causes rapid growth - eutrophic: waterway with high levels of algae with excess nutrients, low dissolved oxygen
- oligotrophic: waterway with low amounts of nutrients stable algae growth and high dissolved oxygen
- hypoxic aquatic system: algal bloom dies → sinks to ocean floor → dead cells consumed by microbes → oxygen is consumed additionally → decreases dissolved oxygen → low oxygen levels
* leads to mass dieoff of fish → creates more waste → creation of dead zones - dead zones: areas of low oxygen in bodies of water caused by nutrient pollution
- oxygen sag: plot of dissolved oxygen far from the pollution source
8.6 Thermal Pollution
- waste resulted from heated water that is discharged after use
* often from power/industrial plants
* other sources: soil erosion, deforestation, wastewater discharge, urban runoff - has many adverse effects on aquatic ecosystems
* warm water holds less dissolved oxygen → decreased dissolved oxygen levels → dieoffs from low DO levels
* doesn’t affect marine mammals (ie. manatees) as they come up to the surface for air
* can impact the survival of organisms with narrow ranges of tolerance
* alteration of feeding, behavior, and migration behaviors
8.7 Persistent Organic Pollutants (POPs)
- organic: often in rings with chlorine outside of it
* synthetic & nonpolar (made with carbon) & cyclical (chlorine atoms)
* fat-soluble: not easily removed once bound on chlorine strands → accumulation over time
* can travel long distances: based on wind directions or waterways - DDT (dichloro-diphenyl-trichloroethane): crystal-like insecticide banned in the US
* used to reduce agricultural pests (ie. mosquitos)
* can cause harm to nearby organisms - PCBs (polychlorinated biphenyl): yellow industrial fluid also banned in the US
* used as a cooler and lubricant
8.8 Bioaccumulation & Biomagnification
8.9 Solid Waste Disposal
8.10 Waste Reduction Methods
8.11 Sewage Treatment
8.12 Lethal Dose 50% (LD50)
- amount of a chemical that is lethal to half of a species’ population
* measured in mg/kg
* used to predict its effects on humans and compare the strength of different substances
* ex. water - least toxic, cyanide - most toxic known to humans
* can be amplified by bioaccumulation
8.13 Dose-Response Curve
- graph that displays the effect of toxins on the human population
* used to determine LD50
* uses data from testing drugs/toxins on a given population
* typically an S-shaped curve
* x-axis: dose (mg/kg)
* y-axis: response% (ie. number of individuals dead)
8.14 Pollution & Human Health
- difficult to establish the relationship between pollutants and human health issues due to the various chemicals/toxins humans are exposed to
* dysentery: inflammation of intestines resulting from bacteria/parasites
* causes bloody stools and cramping
* caused by untreated sewage in rivers/streams
* can be found by fecal coliform testing
* mesothelioma: type of lung cancer resulted from asbestos exposure
* damages heart, lungs, and abdomen
* respiratory issues arises from exposure to ground level ozone (NOx, VOCs, etc.)
* can be mitigated by interpreting AQI
* can compromise lung function by inflaming the linings in the lungs