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New Issue: Water Pollution
Transcript of New Issue: Water Pollution
Pollution of Freshwater Lakes
Alice Coombs, Elaine Hong & Sharnia Navaratnam
Types, Effects, and Sources of Water Pollution
Pollution of Freshwater Streams
Preventing & Reducing Surface Water Pollution
Rivers and other flowing streams can recover rapidly from moderate levels of degradable, oxygen-demanding wastes and excess heat
But this natural recovery process does not work when streams are overloaded with pollutants or when drought, damming, or water diversion for agriculture and industry reduce their flows
Water pollution control laws enacted in the 1970s have increased the number and quality of waste water treatment plants in Canada and most other developed countries
The Credit River in Mississauga, Ontario, was heavily polluted
Then, in the late 1980s, volunteers took on the task of cleaning up the river. They picked up garbage, planted trees, and fenced livestock
Today the Credit River is a place for nature walks, wildlife, and water sports.
: System used for disposal of
in rural and suburban areas.
Primary sewage treatment
: A physical process that uses screens and a grit tank to remove
large floating objects.
Secondary sewage treatment:
A biological process in which aerobic bacteria remove up to 90% of dissolved and biodegradable,
oxygen demanding organic wastes.
Advanced or tertiary sewage treatment
: A series of specialized chemical and physical processes that remove specific pollutants left in the water after primary and secondary treatment.
Scientists can also monitor water pollution by using living organisms as indicator species.
Agricultural activities, such as ploughing fields to grow crops or raising large numbers of livestock, are by far the leading cause of water pollution.
Fertilizers and pesticides, bacteria from livestock and food-processing wastes, and excess salt from soils of irrigated cropland are major agricultural pollutants
Industrial facilities are another large source of water pollution, and mining is the third
Warmer water temperatures can threaten aquatic life by reducing dissolved oxygen levels, and can increase the growth rates of populations of harmful bacteria.
New Issue: Water Pollution
is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or that makes water unsuitable for desired uses
Biological oxygen demand (BOD):
the amount of oxygen consumed by aquatic decomposers
discharge pollutants at specific locations through drain pipes, ditches, sewer lines into bodies of surface water (ex: factories, sewage treatment plants, underground mines)
are scattered and diffuse and cannot be traced to any single site of discharge (ex: acid decomposition and runoff of chemicals into surface water from croplands, livestock feedlots, and logged forests)
Scientists use biological and chemical methods to measure water quality.
When looking at water pollutants, there are a number of categories which include:
Infectious Agents, Oxygen - Demanding Wastes, Inorganic Chemicals, Organic Chemicals
is the name given to the natural nutrient enrichment of lakes, mostly from runoff or plant nutrients such as nitrates and phosphates from surrounding land.
Excessive inputs of nutrients can upset aquatic ecosystems. Near urban or agricultural areas, human activities can greatly accelerate the input of plant nutrients to a lake. This process is called
In lakes and reservoirs, dilution of pollutants often is less effective than in streams for two reasons:
1) lakes and reservoirs often contain stratified layers that undergo little vertical mixing
2) they have little flow
Lakes and reservoirs are more vulnerable than streams to contamination by runoff or discharge of plant nutrients, oil, pesticides, and toxic substances such as lead, mercury, and selenium
These contaminants can kill bottom life and fish and birds
How To Reduce
Non Point Sources:
Prevent agricultural chemicals from affecting bodies of surface water
Reduce soil erosion
Maintain the usage of fertilizers
Don't use steeply sloped lands and planting on buffer zone
Avoiding pesticides and relying more on biological control
Controlling run-offs & infiltration
Using technology to help improve our environment
Steps Scientists Are Taking
Researchers are developing new methods to make renewable biodiesel fuel for vehicles
Planting poplar trees to suck up waste from contaminated hog waste lagoons
Figuring out better ways to use animal wastes (burn it , convert it to natural gases, extract valuable chemicals from manure to make plastic or even cosmetics)
Compress manure into fibre like particles to make furniture
Mainly use a set of laws and acts ( Fisheries Act 1985, Canadian Environmental Protection Act 1988, Canadian Water Act 1970)
Discharging trade policy (Industrialized nations)
Development of better technology
Using the septic tank
Depending more on sewage treatments
Drinking Water Quality
Rural and Suburban areas encourage the use of
One-fourth homes in North America are served by septic tanks
In Canada and U.S. urban areas water borne wastes
(homes, businesses, factories)
use networks of pipes to
sewage treatment plants.
However, these systems have the disadvantage of overflow and blockage when too many people use it.
How is it purified?
First start off by storing surface water in a reservoir (improves taste and clarity by increasing dissolved oxygen content)
Then transferred to a purification plant, it is filtered and chlorinated to meet government standards.
Extra treatment of disinfection depending on area
Drinking Water Quality
Instead of depending on electronic treatment,they depend on hand made
exposing clear plastic bottle filled with contaminated water to intense sunlight (Painting one side of the bottle black to help purify)
Reduces 30-40 % of diseases
Using strips of cloth
Adding a small amount of Chlorine disinfectant solution to plastic or clay water storage vessels
Is it worth the price?
Not as Pure as tap water, yet still more expensive (240-10,000 times more expensive
1.4 million tonnes of plastic water bottles thrown away each year (globally)
Bottled water consists of:
one-fourth of tap water
one-third of bacteria contaminate
one-fifth of various potentially harmful organic chemicals
Groundwater Pollution Overview
Groundwater pollution is a serious problem because these sources supply much of our drinking water
Groundwater can easily become contaminated because it cannot effectively
and create and distribute pollutants
When it becomes polluted, it can't cleanse itself of degradable wastes because it has a very
, much lower concentrations of
, which help decompose waste, smaller populations of
, and the water's cold temperatures slow down chemical reactions that decompose waste
Because of this, it can take anywhere from one hundred to several thousands
of years for polluted groundwater to decontaminate itself
Groundwater Pollution Overview
Groundwater can become polluted when:
people spill gasoline,
, paint thinners and other
onto the ground
chemical storage ponds or underground
and piping have leaks
Tens of millions of people in China and India drink polluted groundwater daily, with high levels of fluoride, which causes them serious tooth damage, and damage to the vertebrae of the neck and back. During this century, scientists expect groundwater contamination to become a major global health problem. Solving this problem is very expensive, and can cost anywhere from $12,000 to over $300,000.
Ocean Pollution Key Terms
oxygen-depleted zones that result from excessive non point inputs of fertilizers and animal wastes from land runoff and deposition of nitrogen compounds from the atmosphere.
materials, often laden with toxic metals, scraped from the bottoms of harbours and rivers to maintain shipping channels
a gooey mixture of toxic chemicals, infectious agents, and settled solids removed from wastewater at sewage treatment plants
harmful algae caused by excessive amounts of nitrate and phosphate plant nutrients
Ocean Pollution Overview
Oceans can break down large amounts of degradable pollutants if they aren't overloaded
This has sparked great debate between scientists
Some say this makes it safer to dump waste into the ocean than bury it on land, while others point out that it may not be a good idea, since we know less about the oceans than the moon, and it would promote further ocean pollution
Coastal waters are greatly affected because many coastal countries are irresponsible about ocean pollution
Deeper waters are also affected because that is where sewage sludge is disposed of
Our pollution of the oceans causes:
other sea creatures
• Freshwater in the world is only 2.5% of the total water available on this planet
• Around 70% of industrial waste is dumped into large bodies of water
• Fourteen billion pounds of garbage ( mainly plastic) is dumped into the ocean each year
• The Ganges River in India is one of the most polluted in the world. It contains sewage, trash, food and animal remains
• Around 250 million people worldwide are affected by disease caused by water pollution
• Water from rain, storm drains, and ditches flows directly to streams and bays with little or no treatment. Storm drains and ditches are DIFFERENT than sewers. They are NOT CONNECTED to a treatment plant
• 1 in 8 people worldwide do not have access to safe and clean drinking water
• Nearly 1 out of every 5 deaths under the age of 5 worldwide is due to a water-related disease
• Globally we use 70% of our water sources for agriculture and irrigation, and only 10% on domestic uses
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