WATER POLLUTION

• What is a Pollutant?– Is a waste material which pollutes air, water or soil– The terms “pollutant” and “contaminant” more or less

synonymous.– Pollutants may be in the form of

• organic or inorganic substances ,• light, • sound• thermal energy• biological agents • invasive species and • wide range of human activities including the combustion of fossil fuels.

– Pollutants may be Primary (active on emission) or secondary (arising from primary pollutants undergoing physical or chemical change)

• WATER POLLUTION• groundwater & surface water• influence human and other biological systems.

• KNOWLEDGE & UNDERSTANDING:– sources.

• variety of freshwater & marine pollution – Types of aquatic pollutants

• floating debris, • organic material, • inorganic plant nutrient (nitrates & phosphates),• toxic metals, • synthetic compounds, • suspended solids, • hot water, • oil, • radioactive pollution,• pathogens, • light, • noise & biological pollutants (invasive spp).

– Biodegradation of organic material • utilizes oxygen, lead to anaerobic decomposition, • in turn leads to formation of methane, H2S and ammonia (toxic

gases).– BOD (Biochemical Oxygen Demand)

• is 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.

• used to indirectly measure the amount of organic matter within a sample.

– Indicator Spp.:• Some species can be indicative of polluted waters and can be

used as indicator spp.– A biotic index indirectly measures pollution

• by assaying the impact on spp within the community according to their tolerance, diversity and relative abundance.

– Eutrophication • Lakes, estuaries, coastal waters• receive inputs of nutrients (nitrates & phosphates), which

results in an excess growth of plants and phytoplanktons.– Dead zones

• Oceans & fresh water• when there is not enough O2 to support marine life.

– Water management strategies • Reducing human activities that produce pollutants

– ex alternatives to current fertilizers & detergents• Reducing release of pollution into the environment

– ex treatment of waste water to remove nitrates and phosphates• Removing pollutants from the environment & restoring

ecosystems – ex removal of mud from eutrophic lakes & reintroduction of plant &

fish spp.

• GUIDANCE– Sources of freshwater pollution

• include runoff, sewage, industrial discharge and solid domestic waste.– Sources of marine pollution

• include rivers, pipelines, atmosphere and activities at sea (operational and accidental discharges).

– The role of positive and negative feedback in the process of eutrophication .• Coastal eutrophication can lead to red tide blooms.

• INTERNATIONAL MINDNESS– Countries with limited access to clean water often have higher

incidences of water illnesses.• TOK

– A wide range of parameters are used to test the quality of water and judgments are made about causes and effects of water quality- how can we effectively identify cause-effect relationships, given that we can only ever observe correlation?

• CANCER VILLAGES-village of Xiditou, SE of Beijing, the

cancer rate is 30 times the national average.-because of water and air pollution by

chemical factories.