Chapter 16 Fresh water resources
Fresh water is a limited source.
16.1 Water circulates through the hydrologic cycle
（水文循环）
? The Earth’s water is constantly circulating,
powered by the heat of the sun and the force of
gravity.
? Water evaporated from ocean precipitates (降水 )
into the ocean,direct route,
? Water evaporated from ocean is blown by winds
until it is over the land and precipitates,(1)
evaporates beck into atmosphere,(2),Infiltrate
the ground,(3),Become part of the snow or
glacier,(4),Drain to a river and back to the sea.
Water table (地下水位 )
Ground water and surface water
? Over-use of ground
water leads to
subside (沉降 ) of land.
16.2 Collectively,we consume huge amounts of water
16.3 Water treatment facilities make water safe for
drinking
? Remove dirt particles and pathogens
Aeration of water improves the odor and flavor of
water.
Final step is to treat water with a disinfectants,
chlorine gas or ozone.
400 people die every hour from diseases caused
by drinking contaminated water.
Water from deep wells may be contaminated by
heavy metals.
16.4 Fresh water can be made from salt water
? Desalinization （淡化）
The two main methods to removing salts from
seawater are distillation and reverse osmosis (反渗
透 ).
16.5 Human activities can pollute water
? Point source is a well defined location where a pollutant
enters a body of water,(waste water from a factory)
? Nonpoint source,agriculture runoff and house-hold
chemicals.
? Polluted underground water
Municipal solid-waste disposal sites are a common
source of ground –water pollution.
16.6 Microorganisms in water alter levels of
dissolved oxygen
? Microorganisms break down organic compounds.
? Aerobic bacteria and anaerobic bacteria
? Biochemical oxygen demand (BOD)
Inorganic wastes,such as nitrate and phosphate
ions lead to eutrophication (富养化 ).
16.7 Wastewater is processed by treatment
facilities
Advanced integrated pond systems treat
wastewater
Low energy cost,smaller amount of sludge
16.8 There are many ways to conserve water
Fresh water is a limited source.
16.1 Water circulates through the hydrologic cycle
（水文循环）
? The Earth’s water is constantly circulating,
powered by the heat of the sun and the force of
gravity.
? Water evaporated from ocean precipitates (降水 )
into the ocean,direct route,
? Water evaporated from ocean is blown by winds
until it is over the land and precipitates,(1)
evaporates beck into atmosphere,(2),Infiltrate
the ground,(3),Become part of the snow or
glacier,(4),Drain to a river and back to the sea.
Water table (地下水位 )
Ground water and surface water
? Over-use of ground
water leads to
subside (沉降 ) of land.
16.2 Collectively,we consume huge amounts of water
16.3 Water treatment facilities make water safe for
drinking
? Remove dirt particles and pathogens
Aeration of water improves the odor and flavor of
water.
Final step is to treat water with a disinfectants,
chlorine gas or ozone.
400 people die every hour from diseases caused
by drinking contaminated water.
Water from deep wells may be contaminated by
heavy metals.
16.4 Fresh water can be made from salt water
? Desalinization （淡化）
The two main methods to removing salts from
seawater are distillation and reverse osmosis (反渗
透 ).
16.5 Human activities can pollute water
? Point source is a well defined location where a pollutant
enters a body of water,(waste water from a factory)
? Nonpoint source,agriculture runoff and house-hold
chemicals.
? Polluted underground water
Municipal solid-waste disposal sites are a common
source of ground –water pollution.
16.6 Microorganisms in water alter levels of
dissolved oxygen
? Microorganisms break down organic compounds.
? Aerobic bacteria and anaerobic bacteria
? Biochemical oxygen demand (BOD)
Inorganic wastes,such as nitrate and phosphate
ions lead to eutrophication (富养化 ).
16.7 Wastewater is processed by treatment
facilities
Advanced integrated pond systems treat
wastewater
Low energy cost,smaller amount of sludge
16.8 There are many ways to conserve water
