Upload
marshall-parker
View
219
Download
0
Tags:
Embed Size (px)
Citation preview
F.6 BIOLOGY PROJECTF.6 BIOLOGY PROJECTRENEWABLE RESOURCE:RENEWABLE RESOURCE:
FRESHWATERFRESHWATER
Chui Wing Chi(7) Wong Suet Yee(28)
Facts about freshwater:
• Freshwater lakes, rivers, wetlands and underground hold only 2.5% of the world's water. By comparison, saltwater oceans and seas contain 97.5% of the world's water supply.
• Over two thirds of the earth's fresh water exists as ice in the form of glaciers and ice caps.
• Of the total world's freshwater supply, about one third is
found underground.
In Hong Kong• Reservoirs
The Tai Lam Chung Reservoir (大欖涌水塘 ) The Shek Pik Reservoir (石壁水塘 )
Plover Cove Scheme(船灣淡水湖) The High Island Reservoir(萬宜水庫)
Importance of freshwater:• Agriculture (Most of the water used by human)
• Heavy industrial processes (e.g. pulp and paper manufacturing, food processing, totally 2/3 of water used.)
Causes of freshwater contamination or pollution:• Hot water from factories discharged into rivers
• Untreated agricultural and industrial wastes including toxic chemicals are dumped into riverspollute drinking waterkill freshwater fishalgal bloom in costal areas
runoff from agricultural fields that contain nutrients, sediment, animal wastes, salts and pesticides cause pollution.
the level of oxygen decreaseskill aquatic organisms
• Toxins leach into groundwater through soil from petrol storage tanks, landfills, and industrial waste sitesdrinking groundwater contains high conc. of heavy metals
Toxins seep into the soil at riverside landfills.
Underground petrol storage tanks pollute groundwater.
Problems of overuse of groundwater:• Water Out > Water In
decrease in groundwater volume• Pumping > Groundwater Recharge
decrease in water table• Drop in water table
higher cost for pumping (electricity)
• Produce irreversible ground subsidence in regions built
on former lake beds, floodplains and deltas • Active and passive saltwater intrusion
Land subsidence
• Occurs in a small spot collapse of the land surface
(sinkhole)
• Occurs over large areas
(may not notice by people)
A sinkhole in Florida, US.
This is the agricultural area of California. Years and years of pumping ground water for irrigation has caused the land to drop. The top sign shows where the land surface was back in 1925! Compare that to where the man is standing (about 1977).
Reference:• http://www.freshwaters.org• http://nature.org/initiatives/freshwater• http://www.biology-online.org• http://www.lakeshoreenvironmental.com• http://www.ec.gc.ca/water• http://www.umac.org/ocp/freshwater/over.htm• http://www.pacificislandtravel.com/nature_gallery/freshwatercontaminatio
n.html• http://lnweb18.worldbank.org/ESSD/ardext.nsf/18ByDocName/Sectorsan
dThemesGroundwater• http://www.geology.sdsu.edu/classes/geol351/08overuse/overuselect.htm• http://wwwga.usgs.gov/edu/earthgwlandsubside.html• http://www.photo.net/ca/sierra• http://www.astroshow.com/west• http://www.uscg.mil/lantarea• http://hktraveler.com/staff/angusli/hkmw-certificate.html