Presentation on theme: "Recall How can we monitor air, water and soil pollution?"— Presentation transcript:
1Recall How can we monitor air, water and soil pollution? Write down what BOD stands for and the definition.How can BOD be used to identify pollution?
2Learning outcomes You should all be able to: Describe an indirect method of measuring pollution levels.Most of you should be able toExplain an indirect method of measuring pollution levels – biotic indexExplain how BOD can be used to assess pollution levels in water.
3Biochemical Oxygen Demand A measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity.
4Biochemical Oxygen Demand Amount of oxygen in the water required to decompose organic wastes (dead plants, leaves, grass clippings, manure, sewerage, food waste, etc.)Indirect measure of pollution
5StarterAnalyse the diagram and explain what is happening.
6How can BOD be used to assess pollution levels? High BOD means low Dissolved Oxygen for plants / fish / invertebrates.High BOD = a lot of organic pollutionDetermined by number of organisms that are present and the rate or respiration.BOD indicates organic matter pollution
7How to measure BOD Take a sample of water Measure the oxygen level Place it in a dark place at 20°C for 5 days.After 5 days measure the oxygen againBOD = difference between 2 measurements.
9Test yourselvesFour factories discharge effluent containing organic matter into rivers. The table shows the volume of discharge into the river and the resulting biological oxygen demand.FactoryVolume of Effluent / 1000 l day-1BOD / mg l -1A14.027B1.053C3.0124D0.833Explain whether these pollution data are for point source or non-point sources.Which pollution source, point source or non-point source is easier to regulate? Explain your choice.Which factory is adding most to the BOD of the river into which it discharges?
10Indirect methods of measuring pollution BODAbiotic factorsBiotic factors
11Pollution Indicators What are pollution indicators? The organisms in polluted water tell you that there is something wrong.
12Examples of pollution indicators Lichens are plants that grow in exposed places such as rocks or tree bark. Air pollutants dissolved in rainwater, especially sulfur dioxide, can damage lichens, and prevent them from growing. This makes lichens natural indicators of air pollution. For example:bushy lichens need really clean airleafy lichens can survive a small amount of air pollutioncrusty lichens can survive in more polluted airno lichens air is heavily polluted with sulfur dioxide.
13Examples of pollution indicators Some invertebrates like bloodworms and rat-tailed maggots, are able to survive in polluted waters
14Examples of pollution indicators While others like mayfly nymphs and stonefly nymphs can only be found in very clean water.
15This is what happens when a stream or river becomes polluted Pollutant is added, which kills some living things.Micro-organisms decompose them, they respire and use up the oxygenLack of oxygen kills other organisms, but a few species stay aliveAs the water flows, oxygen levels gradually increaseOther living things recover too.
16Sewage pollution and invertebrates Distance downstream from where sewage enters the river (m)What the water is likeInvertebrates found (not drawn to scale)Oxygen levelsSewage enters here 0-10Dark and cloudy v. smellyChironomous larva rat-tailed maggotFalling quickly10-100Cloudy bad smellTubiflex worm mosquito larvaVery low
17Sewage pollution and invertebrates Slight smell beginning to clearFlatworm caddis fly larvaGradually rising200+ClearStonefly larva mayfly larvaFreshwater shrimpBack to normal
18Stonefly nymphStonefly nymphs prefer rocky, stony, or gravel bottoms in cool, well-oxygenated, swift- moving streams or small rivers. Any effluent that reduces the oxygen content of the stream quickly kills the nymphs.Biological Monitoring Working Party (BMWP) = 10
19Flattened Mayfly Nymph These are only found in very clean water containing lots of oxygen. They absorb oxygen from the water through their gills.They are primary consumers that eat plants and algae.BMWP = 10
20Cased caddis Fly Larvae Caddisflies use silk (like butterflies) to build cases from gravel, twigs, needles, or sand. Different species build distinct cases, but they often lose them when removed from a stream.BMWP = 8 -10
21Cranefly LarvaeUp to four inches long with a Fleshy, plump, rounded segmented bodyIts digestive track (internal organs) can be seen moving back and forth as it crawls.No legs and the back end usually has several extensions or finger-like lobes.BMWP = 5
22Flatworms Flatworms are unsegmented worms with flattened bodies. Their flatness allows them to shelter beneath stones.Being flat increases the area of skin exposed to the water, which improves the flatworm's oxygen uptake.BMWP = 5
23Freshwater Mite Tiny animals related to spiders. Up to 8mm. They have an oval body and 8 legs.Many are brightly coloured.BMWP = 4
24Leeches Flat, Worm-like, segmented body. Many are scavengers or feed on other invertebrates.Suckers at both ends are used for attachment, feeding, and locomotion.They swim gracefully and quickly in an up-and-down motion.BMWP = 3
25Red Midge Larvae (Bloodworms) These are sometimes called 'bloodworms' because of their bright red colour, but they are not worms at all.They are midge larvae.They eat dead organic matter and can tolerate very low oxygen levels.BMWP = 2
26Tubifex WormsThese are thread-like worms that live in the mud on stream bottoms.They are filterfeedersThey can tolerate extremely low levels of oxygen and are therefore found in polluted water.BMWP = 1
27This shows freshwater fauna as indicators of river pollution.
28Let’s do some monitoring of our own… Read the student instructions and divide the activities between the group – who will take what role?Make sure that you have all the necessary equipment.Visit areas A-D and decide which you think is the most polluted.Complete your results table and method as follows:
29Freshwater species present Example of how to present your findings:Monitoring PollutionOur Group’s methods:Roles: Julio = scribe, Emilia = rain analyst, Rodrigo = particulate analyst, Melanie = photographic investigator, Megan = Freshwater species investigator.pH testing of rain samples using UI paperAnalysis of particulate levels using dust collector cards & hand lenses – given % cover scoreResearch into lichens & analysis of photographic evidence – given score of present/absent/abundantResearch into preferred habitats of freshwater species, and analysis of communities presentOur Group’s findings:AreapH of RainParticulate %Lichen scoreFreshwater species presentRank 1-4ABCDWhat we would do next to help the polluted areas:Find source of pollution – traffic survey & check local industryLobby local council to introduce traffic calming measuressend leaflets to local industry to inform them of measures to reduce the pollution produced
30bushy lichens need really clean air leafy lichens can survive a small amount of air pollutioncrusty lichens can survive in more polluted airno lichens air is heavily polluted with sulfur dioxide.