Lecture 32- 'Marine Pollution" Flashcards
point source pollution
- a singularly identifiable source of pollution such as a direct industrial discharge sewage outfall
- easy to control
nonpoint source pollution
- a diffuse source of pollution
- largest cause of water pollution in the nation
oil spill
- point source oil pollution from oil tankers spills produces catastrophic damage to local waters
- hard to control
the largest source of oil discharge to the ocean overall comes from
nonpoint sources such as household drains and runoff from urban roadways
size of Gulf blow out relative to the Exxon Valdez
5 times bigger
Wild Harbor Marsh
oil is still present at toxic levels 40 years later
Argo merchant
- oil tanker broke apart in 1976
- served as a good controlled experiment
- high morality of pelagic fish eggs and larvae which were coated with oil
- oil can also affect food chains
tar ball
- sand with oil
- can go back into the ocean, making the oil even deeper than it started
Minamata Bay, Japan (1950s to 1960s)
- industrial mercury was discharged into the bay and it entered the fish populations that were consumed
- led to birth defects
the main source is not point source of industries discharging heavy metals into oceans but
discharging heavy metals from smoke stacks from burning coal
smoke stacks
- not only release CO2 into the atmosphere but heavy metal
- mercury in the air goes into the ocean when it rains and while low levels is not harmful, it builds up BIOACCUMULATION
unlike carbon, mercury
- are not easily lost in the transfer from one trophic level to the next
mercury concentrations
- increase as you go higher up the trophic level (increases by 10 fold)
- those at the top of the food chain will have the most concentration of mercury
marine debris
plastic
the biggest victims of plastics in oceans
- seabirds
- pick up plastic thinking it’s food and their chicks die from starvation
aggregation of plastic in subtropical gyre regions
- surface water (westerly winds and trade winds) converges into the center of the gyre bringing floating plastic with it
- water downwells but the plastic stays and accumulates over years
microplastic sources
- large plastic that degrades
- micro-beads in cosmetics
- synthetic clothing fiber
- industrial processes
microplastic
small plastic particles less than 5 mm in diameter
big concern of microplastic
- can absorb organics onto their surface and these potentially toxic organics are then moved up the marine food web
- also consumed by coral reefs
primary treatment
- simplest and least effective treatment
- solids are settled out of suspension
- fluid is discharged into the environment
primary treatment only removes
1/3 of the total organics and virtually none of the dissolved minerals
secondary treatment
- aerobic microorganisms consume the organic matter down to low levels
- most of the nitrogen and phosphorous remains in sewage effluent
primary and secondary treatments together can remove up to
90% of the total organic compounds
nitrogen and phosphorous from the effluent stream of secondary treatment
can cause phytoplankton to bloom and decrease the oxygen in the ocean
tertiary treatment/ advanced waste treatment
- remove plant nutrients to avoid eutrophication of surface water
- quite expensive
primary, secondary, and tertiary sewage treatment facilities employ a
cumulative process
secondary treatment facility implies
both solids and dissolved organics have been removed
tertiary treatment facility implies that
solid, dissolved organics, and plant nutrients have all been removed
getting outfalls offshore and below the thermocline
reduces the amount of effluent reaching the surface layer of the ocean
what is the largest pollution problem in the coastal waters of the United States?
plant nutrients (primarily nitrogen and phosphorous)
increased nutrient loads in coastal waters
stimulate exceptional algal (phytoplankton) growth which die and are consumed by microbes which will also consume oxygen
oxygen concentration near the bottom of the water column
brought down to very low levels which creates a dead zone
close connection between global increases in nitrogen flux to the coastal environment and
global increases in fertilizer consumption
increased fertilizer demand is largely driven by
- human population increases
- increases in per capita meat consumption
- increases in corn ethanol production
- transition to industrial farming practices
currently, more than — of all agricultural land is devoted to growing feed for livestock
2/3 for growing feed while 8% is used to grow food for direct human consumption
traditional way of farming
- spread manure to help grow corn (food for cows)
- recycle loop
modern farm
- grow corn and animals in two different places, no recycle
- buy 100% fertilizer, 37% enters the stream
corn
- leaky crop for nitrogen
- important driver of increased fertilizer use
- tile drains and bare fields in winter aggravate this
CAFOs
apply liquid animal land which often leaches into waterways
more than half of US rivers are unsuitable for aquatic life
due to nutrient pollution from industrial agricultural practices
dead zone
area where water at the bottom is low in oxygen
largest dead zone ever recorded (Gulf of Mexico)
summer 2017
blooms of toxic phytoplankton
- red tides
- brown tides
- sometimes colorless
- intense blooms can kill marine life
shellfish
toxins are concentrated to high levels in shellfish so it can be harmful to humans eating them
frequency and intensity of harmful algal blooms is tied to
increases in nutrient fluxes to the coastal zone
some actions that could help change things
- east less factory meat
- advocate for eliminating corn ethanol subsidies
two additional reasons factory meat is bad for the planet
- impact of freshwater demand
- impact on greenhouse gas emissions
— of the earth’s groundwater basins now under threat
1/3
going vegetarian reduces water footprint by almost
60%
greenhouse gas production from meat production
- methane release
- carbon dioxide
- nitrous oxide
livestock contributes — to total GHG emission
14.5%
overall contribution by livestock including land use changes
51% to total GHG emission
if everyone in the US substituted beans for beef
the US could come close to meeting its 2020 greenhouse gas emission goals
