PollutionThe contamination of the Earth and atmosphere to such an extent that normal environmental processes are adversely affected.This includes natural causes and is subjective to the strength of the ecosystem:
Point Source Pollution• comes from a specific source, like a pipe• factories, industry, municipal treatment plants• can be monitored and controlled by authorities
Nonpoint source pollution• Nonpoint source pollution is pollution associated with storm water or runoff• It cannot be traced to a direct discharge point and so is harder to regulate
Sources of pollution 8% Sewage 27% Mining 20% 8% Agriculture Construction and Livestock 9% Domestic 17% and Industry commercial 11% Dredging
5.2 DETECTION ANDMONITORING OFPOLLUTION
What to measureWater quality Air quality• Dissolved oxygen • Sulfur dioxide (SOx)• pH • Oxides of nitrogen (NOx)• Phosphate • Ozone (O3)• Nitrate • Volatile organic• Salt compounds (VOCs)• Ammonia • Particulate matter (PM) (Can use secondary data)
How to measure water qualityIndicator Method InterpretationDissolved Use a test kit or meter or sensor for • healthy clean water shows >75% oxygen saturationoxygen dissolved oxygen. Follow instructions to • polluted water shows between 10-50% oxygen measure the amount of oxygen saturation saturation in a sample of water. Oxygen is usually • raw sewage contains 10% saturation of oxygen or measured in percentage saturation. lesspH Dip pH or universal indicator paper into a • pH 1 -6 indicates that the water is acidic, pH 1 is very sample of water. Compare the colour of acidic the pH paper with the pH colour chart.. • pH 7 indicates a neutral solution Record the pH number (e.g. pH 8). • pH 8-11 indicates that the water is alkaline, pH 11 is very alkalinephosphate Use a test kit. Follow instructions to • clean water contains >5 mg dm-3 measure the amount of phosphate in a sample of water. Phosphate is measured in • polluted water contains 15-20 mg dm phosphate -3 mgdm-3.nitrate Use a test kit. Follow instructions to • clean water contains 4-5 mgdm-3 measure the amount of nitrate in a sample of water. Nitrate is measured in mg dm-3. • polluted water contains 5-15 mg dm-3 nitratesalt (as Use a test kit or meter or sensor. Follow • seawater contains 20 000 mg dm-3chloride) instructions to measure the amount of chloride in a sample of water. Salinity is • tidal or brackish water contains 100-20000mgdm-3 measured in mg dm-3. chlorideammonia Use a test kit. Follow instructions to • clean water contains 0.05-1.00 mg dm-3 measure the amount of ammonia in a • polluted water contains 1-10mgdm-3 sample of water. Ammonia is measured in • raw sewage contains 40 mg dm-3 ammonia mgdm-3.dissolved Use a test kit or meter or sensor for • healthy clean water shows >75% oxygen saturationoxygen dissolved oxygen. Follow instructions to • polluted water shows between 10-50% oxygen measure the amount of oxygen saturation saturation in a sample of water. Oxygen is usually • raw sewage contains 10% saturation of oxygen or measured in percentage saturation. less
Example method 1: soil pHSoil pH can be measured using a universal indicator as follows.1. Take a small soil sample from a known depth (horizon) of soil.2. Place about 1 -2 cm of soil in the bottom of a test tube.3. Add 1-2 cm of barium sulfate (this causes the clay to settle leaving a clear solution).4. Fill the tube with distilled water and shake.5. Add a few drops of universal indicator to clear the solution. Compare the colour of the liquid to the colour of the chart provided. The pH can be read off to the nearest 0.5. Report write up: DCP, DCE
Example method 2: air qualityVariations in the amount of dust and solid matter in an area can be assessed by placing a large number of clean, empty yoghurt pots around the area. The area should include a mix of locations (e.g. road junctions, commercial areas, residential areas, parks and woodlands, rivers, power stations and so on). If possible, attach the pots to buildings or structures (e.g. lampposts) at 2-3 metres high in as many different locations as possible. Setting the pots this high reduces the chance of interference from the public. Leave the pots for a period of time - this could be up to a number of weeks over the summer vacation. At the end of the time period, collect the pots and measure the amount of dust and particulate matter. Alternatively, with a digital camera, photograph the material in the pot and estimate the percentage of the base that is covered with dust.As an alternative to using pots, coat cards with a sticky substance such as Vaseline. Hang the cards in a variety of locations (e.g. around your school) and estimate the percentage covering of dust or amount of discolouring after a set time period (e.g. 1-7 days). It is possible to combine either of these methods with a survey of the variation in the amount of weathering of local rocks. Report write up: DCP, DCE
Indirect methods1. BOD (Biochemical oxygen demand)2. Biotic index
BOD – biochemical oxygen demand• Biochemical oxygen demand is a measure of the quantity of oxygen used by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter.• Oxygen consumed in the decomposition process robs other aquatic organisms of the oxygen they need to live decreasing diversity.• BOD is the difference in oxygen levels after the sample is incubated for 5 days in the dark at 20ºC.
Biotic indexAdvantages of an indirect method:- More accurate in that it allows the monitoring over a longer time span through a plant or animal rather than an instantaneous measurement of a chemical- Provides a real measurement of the environment – if a factor was missed (eg. lead concentrations), this method may better account for all pollutionWhat are the disadvantages?(other factors influencing biotic index, undiagnostic to actual problem…)
Whatrelationshipscould beimplied here?
5.3 APPROACHES TOPOLLUTIONMANAGEMENT
ApproachPollution management can be strategically engaged with using a three stage system of1. replace with alternatives2. regulate the release3. restore the environment.
DDT case studyAdvantages:• Kills insects that cause disease drastically decrease cases of disease( eg. Ecuador: malaria cases dropped over 60% during 1993 to 1995 )• Malaria kills about 1-3 million people annually
DDT case studyDisadvantages:• Insects populations can become resistant within six years• Chemical builds up in the food chain (bioaccumulation)
Other case studies• Rutherford text p282-284
5.4 EUTROPHICATION Video: Water pollution in general Animation
What have the following images got to do with the environment? Red algal pollution Sewage Microscopic animals & plants A polluted lake
Nitrates are found in very lowFACT 1: concentrations in the environment Rapeseed plant: nitrate deficient – older, lower leaves yellow This limits how fastFACT 2: plants can grow + - Tomato plant +/- nitrate
Farmers then add fertilisers toFACT 3: improve the soils fertility. If a farmer adds too muchFACT 3: fertiliser it runs into rivers and streams…….fertilising them!
This is called ….. …..EUTROPHICATION
BEFORE EUTROPHICATION AFTER EUTROPHICATIONEutrophication will kill all animals and plants in the water
Eutrophication is a 6 stage processLACK OF OXYGEN DEATH OF PLANTS GROWTH OF BACTERIA GROWTH OF PLANTS SUFFOCATIONADDITION OF NITRATES & PHOSPHATES You have 5 minutes to put these into the correct order!
Eutrophication is a 6 stage process Here is the correct sequence….ADDITION OF NITRATES (& PHOSPHATES) Farmer adds too much NPK fertiliser. When not absorbed by plants nitrate and phosphate runs off the land into the water.
GROWTH OF PLANTS N & P fertilises the water, leads to major plant growthDEATH OF PLANTSGROWTH OF BACTERIA Bacteria feed on dead material and use up all the oxygenLACK OF OXYGEN Anoxic conditions means most animals dieSUFFOCATION
Eutrophication is a 6 stage process Here is the correct sequence….ADDITION OF NITRATES & PHOSPHATES GROWTH OF PLANTS DEATH OF PLANTS GROWTH OF BACTERIA LACK OF OXYGEN SUFFOCATION