Lecture Nineteen - Pollution Flashcards
What is the inter nations geosphere biosphere programme?
An international scientific research program on global change.
Its objectives are:
“To describe and understand Earth System dynamics,
Focussing on interactive biological, chemical and physical processes,
The changes that are occurring in these dynamics,
And the role of human activities in these changes. ”
Studies interactions among biological, chemical and physical processes and human systems.
Collaborates with other programmes to develop and impart the understanding necessary to response to global change.
What is global change?
Global-scale changes that affect the functioning of the Earth System.
Much more than climate change.
Socio-economic as well as biophysical.
For example, changes in: Nitrogen fixation Temperature Biodiversity Atmosphere composition Population N in the coastal one Forest cover Fisheries exploitation.
“Global change can be viewed from one perspective as the sum of all environmental pollution” JT Trevors.
What percentage of oil reserves have human used?
- In the last 150 years humankind has exhausted 40% of the known oil reserves that took several hundred million years to generate
- Nearly 50% of the land surface has been transformed by direct human actionbig consequences for biodiversity, nutrient cycling, soil structure, soil biology, and climate.
Explain nitrogen in the context of climate change.
Nitrogen: controls plant diversity and productivity, dynamics of grazers and predators.
• microbes break down organic compounds.
• plants use inorganic NH4, NO3.
“Human activity has doubled the rate of nitrogen entering land-based N2 cycle.” Excessive N pollutes!
- Human-driven N2 fixation (exponential growth in fertiliser manufacture since 1940s).
- Fossil fuel burning, vehicle emissions, industry – release previously locked up N2 (from nitric oxide).
- Vast increase in N crops (soybean, peas, alfalfa).
These three dot points have lead to:
• Increased nitrous oxide (N20) in atmosphere - greenhouse gas; nitric oxide (NO) – smog, acid precipitation.
• Acidification of soils, increased NO3 in waterways – up to 20X.
• Increased nitrogen in rivers, estuaries and coastal waters.
Tonnes of N and P discharged by inland sewage plants each year.
Explain the phosphorus cycle in the context of climate change.
- No atmospheric component
- Plants absorb phosphate (PO4 )
- Soil particles bind PO4
- Dissolved PO4 leaches into waterways
- PO4 accumulates in sediment
- Human activity - X5 increase in P transfer from rocks
- Phosphorus essential for ATP, DNA, phospholipid molecules
Tonnes of N and P discharged by inland sewage plants each year.
What is water pollution?
• Substances at levels high enough to threaten health, survival or activity of humans or other critters.
Point sources:
• Discharge from specific location e.g. drain pipe, ditch, sewer outlet, oil refinery
*Relatively easy to identify, monitor and treat the wastes.
Non-point sources:
• No specific discharge location.
• Run-off from farms, lawns, logged areas, roads etc - into waterways.
*Harder to identify and treat.
What are water borne diseases?
Viruses, bacteria and parasites.
Can include typhoid, cholera, bacteria, dysentery, polio, hepatitis and parasites.
Largely form human and animal faeces.
Can be point or non-point.
What are oxygen demanding wastes?
Sewage, paper pulp and food waste.
Lowers dissolved oxygen content.
Usually point source.
How can plant nutrients be pollutants?
Fertilisers and sewage.
Causes nuisance algal blooms.
Impact on biodiversity.
Usually non-point source.
Explain cyanobacteria blooms.
Ponds and lakes covered in scum .
Poisonous to humans and livestocks.
Increase in bacterial decomposers, oxygen shortages and fish kills.
What are the toxins in blue green algae?
- Hepatotoxins (Anabaena, Microcystis, Nodularia) – liver failure, possibly tumours. Microcystins – the most significant drinking water quality issue re blooms in SE Australia*.
- Neurotoxins - (Anabaena, Nostoc) - paralysis.
- Endotoxins – dermatitis and allergies * 1.3ug/L = maximum permitted.
What causes red tides?
Red tide-causing dinoflagellates (phytoplankton): growth and reproduction stimulated by eutrophication – up to 1 x 106 cells ml-1.
What is PSP?
PSP - Paralytic Shellfish Poisoning.
Toxic dinoflagellates - concentrated by shellfish (eg. oysters, mussels). Saxitoxin – alkaloid.
Humans and birds - poisoned by eating toxic shellfish.
Seals and fish - affected by consuming contaminated fish (that have eaten toxic shellfish).
Also: NSP (Neurotoxic) DSP (Diarrhetic).
What are inorganic toxins as pollutants?
Heavy metals: mercury, lead, nickel.
• Highly toxic, persistent, bio-accumulate • result from mining activities.
Non-metallic salts: sodium chloride, selenium, arsenic.
• Result from irrigation in arid regions.
Acids:
• In coal mining run-off.
• Also derive from SO2 and nitrogen oxides in air – fall as acid rain.
Usually Non-point source.
What is acid rain?
Nitrogen oxides (NOx) and sulfur dioxide (SO2): • Dry deposition: fall to ground, converted into acids in water (from 20-50% of all ‘acid deposition’). • Wet deposition: dissolve & oxidize to form nitric acid (HNO3) and sulfuric acid (H2SO4).
Clean (unpolluted) rain is slightly acidic:
H2O (l) + CO2 (g) → H2CO3 (aq) – carbonic acid.
Carbonic acid then can ionize in water forming low concentrations of hydronium and carbonate ions: 2 H2O (l) + H2CO3 (aq) ↔ CO32− (aq) + 2 H3O+ (aq).
• Leaching of Ca and Mg --> lower NPP & soil buffering • Aquatic ecosystems • Mortality • Reproduction • Growth
