Water Flashcards
How much cubic miles of rain falls on the continents?
27,000
What are the sources of freshwater?
Glaciers and ice caps
Rivers and streams (flowing or lotic habitats)
Lakes, wetlands and reservoirs
Groundwaters
Statistics on safe drinking water and sanitation
884 million without access to safe drinking water (2008) estimated 672 million 2015
2.6 billion without access to basic sanitation
Points on water quality and human health
Lack of safe water and sanitation is worlds single largest cause of illness
~5-10 million people die per year of water borne diseases
Millions more seriously debilitated
What is guinea worm disease?
Cause by large nematode (roundworm) Dracunculis medinensis
Life cycle - human drinks unfiltered water containing Copepods with L3 larvae
- larvae released when Copepods die where they penetrate the stomach and intestinal wall, mature and reproduce
- fertilised worm travels to surface of skin and causes blister, then discharges larvae
- L1 released into water where they are consumed by copepod
- undergo 2 molts in the copepod and become L3 larvae
No effective drug or vaccine, can be completely eradicated by providing clean drinking water
What is schistosomiasis?
Affects 200 million people worldwide in more than 70 countries in tropics and sub tropics
Flukes (schistosomes) transmitted by freshwater snails
Parasite gains entry via skin, travels to liver and causes liver failure
Name three protozoan parasites and two bacterial diseases associated with water
Cryptosporidium
Giardia
Acanthamoeba
Cholera
Legionnaires disease
What is cryptosporidium?
Most common non-viral cause of diarrhoea in humans and domestic animals
Invades epithelial cells of the intestine
Particular problem for immunocompromised
Resistant to drinking water disinfectants
No effective drugs
Criminal defence to provide water in the UK with more than 1 cryptosporidium per 10L
What is cholera?
7 cholera pandemics since 1817
Caused by Vibro cholerae - produces endotoxins which act on small intestines
What are the four main groups of toxic chemicals?
Persistent organic pollutants (POPs)
Metals
Nanotoxicants
Endocrine disrupters
What are POPs? And why are they bad for the environment?
Resistant to degradation Long range transport Tendency to accumulate in fatty tissues Low water degradability and reactivity Low water solubility Lipophilic Toxic
Example of a POP
DDT
caused egg shell thinning in birds due to bioaccumulation
Points on pollution
Total world production has reached 1.2 million tonnes
Only 4% has been destroyed by incineration
31% is reckoned to have reached the open environment
Remaining 65 percent still either in use or in landfill sites
