IB ESS HL 4.4.5 Eutrophication Questions

Explain causes and consequences of eutrophication.

Exam points

define eutrophication and identify nutrient sources such as untreated sewage, fertilizer runoff and organic waste, together with algal blooms and hypoxia
explain the eutrophication sequence from nitrate or phosphate enrichment to algal growth, shading, decomposition, increased BOD, oxygen depletion, anaerobic conditions, hydrogen sulfide and possible pathogen impacts
analyse and evaluate eutrophication evidence in aquatic and terrestrial contexts, comparing nutrient benefits in soil with pollution risks in water and considering prevention, monitoring and stakeholder trade-offs

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Study 4.4.5—Eutrophication conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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Pollutant	Unit	2011	2012	2013	2014	2015
Nitrate	kt	32.80	32.60	31.30	37.10	32.90
Phosphate	kt	4.50	4.40	4.00	4.80	4.40
Lead	kg	186.18	215.91	201.00	41.21	3.57
Chromium	kg	508.68	460.10	438.05	266.65	93.59

Pollutants in wastewater discharged into Beijing rivers, 2011-2015

Figurewastewater pollutants
• Nitrate (kt): 2011 32.80; 2012 32.60; 2013 31.30; 2014 37.10; 2015 32.90.
• Phosphate (kt): 2011 4.50; 2012 4.40; 2013 4.00; 2014 4.80; 2015 4.40.
• Lead (kg): 2011 186.18; 2012 215.91; 2013 201.00; 2014 41.21; 2015 3.57.
• Arsenic (kg): 2011 28.09; 2012 21.34; 2013 15.11; 2014 8.00; 2015 11.04.
• Mercury (kg): 2011 1.72; 2012 0.49; 2013 0.64; 2014 0.10; 2015 0.33.
• Cadmium (kg): 2011 12.44; 2012 17.90; 2013 17.45; 2014 0.58; 2015 0.70.
• Chromium (kg): 2011 508.68; 2012 460.10; 2013 438.05; 2014 266.65; 2015 93.59.

With reference to Figure, identify the year in which eutrophication was most likely to have occurred.

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IB ESS HL 4.4.5 Eutrophication Questions question 1