UGRC 144 Science and Technology in Our Lives/Geohazards · •Air pollutants can be natural or human-produced, and they could be primary or secondary in origin. •Primary pollutants

College of Education

School of Continuing and Distance Education2014/2015 – 2016/2017

UGRC 144

Science and Technology in Our

Lives/Geohazards

Session 13 – Environmental Pollution

Lecturer: Dr. Patrick Asamoah SakyiDepartment of Earth Science, UG

Contact Information: [email protected]

Session Overview

• This session looks at some important categories of pollutants and the nature of the problems each presents.

• Most of the activities we engage in our homes, schools, offices and industries cause pollution to the environment.

• We shall, therefore, discuss the possible solutions to existing water-, air-, and land-pollution problems.

Dr. Patrick A. Sakyi, Dept. of Earth Science Slide 2

Session Outline

The key topics to be covered in the session are as follows:

• Topic One – Water Pollution

• Topic Two – Air pollution

• Topic Three – Soil Pollution


Reading List

• Chapters 15, 16 and 17 of Environmental Geology 4th

Edition, Wm. C. Brown Publishers – by Carla W Montgomery (1995)

• Chapter 15 of Geology and the Environment. 3rd

Edition. Brooks/Cole Thomson Learning – by Pipkin, B. W. and Trent, D. D. (2001)

• Unit 3, Sections 4 & 5 of UGRC 140 II Geohazards –Institute of Continuing and Distance Education.


WATER POLLUTIONTopic One


Water Pollution

• Water pollution is any chemical, physical or biological change in the quality of water that has a harmful effect on any living thing that drinks or uses or lives (in) it.

• Any natural water, be it rainwater, surface water, or groundwater, contains dissolved chemicals. Some of the substances that find their way naturally into water are not healthy to us or other forms of life.

• Water pollution can also make water unsuited for the desired use.


Water Pollution

What is a Water Pollutant

• From a public health or ecological point of view, a pollutant is any substance in which an identifiable excess is known to be harmful to human beings and other living organisms.

• For example, excessive amounts of heavy metals, certain radioactive elements, phosphorous, nitrogen, sodium, fluoride, and other useful elements, as well as certain pathogenic bacteria and viruses, are all pollutants.


Water Pollution

What is a Water Pollutant

• The residence time of pollutants in water is also very important.

• For example, water in rivers have short average residence time of about two weeks, and therefore, one time pollution event such as sewerage spills, will be relatively short-lived. This is because the water will soon leave the river environment, accompanied by the pollutant.

• Groundwater have long residence times, ranging from hundreds to thousands of years. Therefore, natural removal of pollutants from groundwater is a very slow process, and correction is very costly and difficult.


Water Pollution

Point and Nonpoint Pollution Sources

• Point Sources are sources from which pollutants are released at specific readily identifiable locations into the surface water. Examples are; a sewer outlet, a steel mill, and a septic tank.

• Nonpoint Sources are sources that are more diffuse, cannot be traced to a single site of discharge. Thus, the source is more spread out.

• Examples include; fertilizer runoff from farmland, acid mine drainage from abandoned strip mine, acid deposition from the air, or runoff of sodium (Na) or calcium (Ca) chloride from road salts.


Water PollutionSelected Water Pollutants

• Many different materials and substances may pollute surface water or groundwater. These include;

– Oxygen-demanding waste - substances are those that react with dissolved oxygen in water, thereby depleting the amount of oxygen in water (e.g. urban sewerage and dead leaves)

– Nutrients such as phosphorous (P) and nitrogen (N) are released from fertilizers, detergents, and the products of sewerage treatment plants, in the form of phosphates and nitrates, to pollute rivers.

– Pathogenic organisms are disease-causing organisms that are responsible for the waterborne human diseases such as; cholera, typhoid infections, hepatitis, dysentery, urinary tract infection, diarrhoea.


Water PollutionSelected Water Pollutants

– Oil discharged into surface water, usually the ocean, has caused major pollution problems resulting in the death of aquatic organisms. . These discharges usually involve oil tanker accidents, spillage and leakages from ruptured pipelines

– Heavy metals are inorganic industrial pollutants that are potentially toxic. are produced by manufacturing, mining and mineral processing activities, and include mercury, lead, cadmium, plutonium, zinc and arsenic.

– Hazardous chemicals are synthetic organic and inorganic compounds that are toxic to humans and other living things. They include organic chlorine compounds, acids, organic solvents and fluorides.

– Sediment pollution is caused by rock and mineral fragments of silt-, clay-and even finer size particles that can be suspended in water. It causes water to be murky and unpleasant to look at, swim in, or drink. It also reduces the light available to underwater plants and blankets food supplies and the nests of fish, thereby reducing fish and shellfish populationsDr. Patrick A. Sakyi, Dept. of Earth Science Slide 11

Water Pollution

Causes of Water pollution - by natural processes and human activities.

• Climate influences water quality because temperature, precipitation, and wind affect the physical, chemical, and biological characteristics of water.

• Vegetation also falls into water, mixes with it breaks apart, decomposes and becomes part of the water, potentially changing its colour.

• Geology - Groundwater, moving through rocks and soils may pick up a wide range of compounds such as magnesium, calcium, fluorides and chlorides, thereby increasing their concentrations above acceptable limits.


Water Pollution

Causes of Water pollution - by natural processes and human activities.

• Domestic discharges mainly in septic systems and sewerage treatment plants can be a source of contaminants, including bacteria, viruses, nitrates from human waste, and organic compounds.

• Wastewater from Industrial-manufacturing and service industries have high demand for water (for cooling, processing and cleaning purposes).

• Agricultural: Pollution from agriculture runoff of fertilizers during storm into surface water, spillage of fertilizers and pesticides during handling, runoff from the loading and washing of pesticide sprayers or other application equipment.

• Other sources of contamination are solid waste disposal, storing hazardous materials, and leakages from storage tanks holding petroleum products, acids, solvents and chemicals


Water Pollution

Effects of Water pollution

• Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and subsequently to the humans who eat them

• Heavy metals can slow development, result in birth defects and some are carcinogenic.

• Toxic compounds in industrial can cause immune suppression, reproductive failure or acute poisoning.

• Microbial water pollution often result in infectious diseases such as cholera and typhoid fever being the primary cause of infant mortality.


Water Pollution

Effects of Water pollution

• Organic matter and nutrients causes an increase in aerobic algae and depletes oxygen from the water column. This causes the suffocation of fish and other aquatic organisms.

• Suspended particles in freshwater reduces the quality of drinking water for humans and the aquatic environment for marine life.

• Suspended particles can often reduce the amount of sunlight penetrating the water, disrupting the growth of photosynthetic plants and micro-organisms.


Water Pollution

Controlling Water Pollution

• Some of the best opportunities available for preventing water pollution involve the 3Rs, namely; reduce, reuse, and recycle.

– When we reduce our generation of garbage and other refuse, less solid waste ends up in landfills. Less solid waste in landfills provides less opportunity for creating leachate.

– Reusing treated and disinfected wastewater for irrigation or reusing process waters for wash down or cleanup.

– Recycling paper helps prevent water pollution by lowering the demand for raw timber, allowing more trees to remain in the forest for stabilizing the soil, cooling tributary waters, and otherwise benefiting water quality.


AIR POLLUTIONTopic Two


Air Pollution

• Air Pollution is the release of pollutants in excess quantities into the atmosphere that affect the quality of air and has a harmful effect on any living that inhales it.

• Increased urbanization and industrialization has caused urban air in particular, to become increasingly polluted, with the consequent environmental effects.


Air Pollution

Types and Sources of Air Pollution

• There are two major kinds of air pollution sources, namely stationary and mobile.

• Stationary sources are those with a relatively fixed location, and these include point sources, fugitive sources and area sources.

– Point sources emit air pollutants from one or more separate controllable sites, such as smokestack of industrial power plants.


Air Pollution

Types and Sources of Air Pollution

– Fugitive sources generate pollutants from open areas exposed to wind processes. These include dirty and dusty roads, construction sites, farmlands, and surface mines.

– Area sources are locations that emit air pollutants from several sources within a well-defined area. Examples include small urban communities or areas of intense industrialization within an urban complex.

• Mobile sources are those which move from place to place, while producing emissions, and include automobiles, aircraft, ships, and trains.


Air Pollution

Air Pollutants

• Most air pollutants are either gases or particulate matter (particles)

• Air pollutants can be natural or human-produced, and they could be primary or secondary in origin.

• Primary pollutants are emitted directly into the air and include particulate matter, SO2, CO and NO2.

• Secondary pollutants are produced when primary pollutants react with normal atmospheric compounds.


Air Pollution

Air Pollutants

• Most air pollutants are either gases or particulate matter (fine solid particles, mostly containing Pb, As, Cd and asbestos particles)

• Air pollutants can be natural or human-produced, and they could be primary or secondary in origin.

• Primary pollutants are emitted directly into the air and include particulate matter, SO2, CO, H2S, HF and NO2.

• Secondary pollutants are produced when primary pollutants react with normal atmospheric compounds. Examples are the ozone (O3)Dr. Patrick A. Sakyi, Dept. of Earth Science Slide 22

Air Pollution

Acid Rain

• Acid rain is rain that is more acidic than normal, causing the pH of the rain water to less than 7.

• Even though many gases in the atmosphere contribute to the acidity of rain, discussions on acid rain focus on the sulphur gases that react to form atmospheric sulphuric acid (H2SO4), which is a strong acid that dissociates extensively.

• All natural precipitation is actually somewhat acidic as a result of the solution of gases such as CO2 to form carbonic acid H2CO3. However, carbonic acid is not as strong as sulphuric acid.


Air Pollution

General Effects of Air Pollution

• Air pollutants affect human health, ecosystems, and the biosphere. The most serious of these effects are damage to plants and aggravation of chronic illness in human beings.

• Effects on Soil and Water: when air pollutants are deposited, soils and water may become toxic. Soils may also be leached of nutrients by pollutants that form acids.

• Effects on Vegetation include damage to leaf tissue, or fruit, reduction in growth rates or suppression of growth

• Dust settled on the surfaces of green plants may interfere with their absorption of carbon dioxide and release of oxygen and water.Dr. Patrick A. Sakyi, Dept. of Earth Science Slide 24

Air Pollution

General Effects of Air Pollution

• Effects on Animals: the effects of air pollution on vertebrate animals include injury to the respiratory system, damage to eyes, bones and increased susceptibility to disease and other stress-related environmental hazards. Heavy dust may affect the breathing of animals.

• Effects on Human Health: this include toxic poisoning, eye irritation, and irritation of the respiratory system.

• Effects on Human Artifacts such as buildings and monuments include discoloration, erosion, and decomposition of construction materials.


Air Pollution

Controls of Air Pollution

• Reducing air pollution requires a variety of strategies tailored for specific sources and types of pollutants. The best strategy is to reduce emission through conservation and efficient measures, such as burning less fossil fuel.

• Control of Particulates - particulates emitted from stationary sources are easier to control than are very small particulates of primary or secondary origin released from mobile sources such as automobiles. For example, particulates from waste piles can be controlled by covering the waste pile with plastic or other material.


Air Pollution

Controls of Air Pollution

• Dust on a road can be controlled by spreading water or a combination or water and chemicals to hold it down.

• Soil piles on the other hand can be protected by planting them with vegetation that inhibits wind erosion.

• Control of Automobile Pollution - Automobile pollutants like CO2, NO2, and hydrocarbons can best be controlled by regulating automobile exhaust, which is the source of most of the anthropogenic portion of these pollutants.

• Control of Sulphur Dioxide – SO2 emissions from stationary sources as power plants can be reduced by removing the oxides from the gases in the stack before they reach the atmosphere.


SOIL POLLUTION – SOIL CONTAMINATION AND LAND DEGRADATION

Topic Three


Soil Pollution

• Soil pollution occurs when materials that are harmful to human and other living things are accidentally or deliberately released into soils, thereby increasing their concentration above the natural levels.

• Many of these materials, including chemicals may act as soil contaminants.


Soil Pollution

• Among the most significant soil pollutants are;– Hydrocarbons

– Heavy metals - e.g., arsenic (As), cadmium (Cd), mercury (Hg),

– Lead (Pb)

– Herbicides - substances used to kill unwanted weeds

– Pesticides - substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest

– Chlorinated hydrocarbons

– Pathogens - microorganisms that have the capacity to cause disease


Soil Pollution

Sources of Soil Pollutants

• There are several different sources from which pollutants may enter the soil and eventually contaminate groundwater.

– Sewerage treatment plants

– Incinerators, where solid wastes are burned

– Automobiles

– Agricultural lands

– Industrial plants

– Spillage and leakage from tanks and pipes.


Soil Pollution

Sources of Soil Pollutants• Most of these sources have been described in the two

previous subsections under Water and Air Pollution.

• Once the soil is polluted, it becomes a source for future release of contaminants to both surface water and groundwater.

• Polluted soils or land may modify the soil quality inhibit the growth of vegetation on land.

• A polluted soil reduces nutrient supplies to plants, thus changing food supplies to humans and the breeding habitats and grazing patterns of certain animals.


Summary

• In this session we looked at the three main types of pollution, namely water, air and soil pollution, and the variety of pollutants released into the environment.

• We also discussed the various sources of pollutants, including solid and liquid wastes, industrial plants, automobiles, and power plants that burn fossil fuels.

• Some of the pollutants are oxygen-consuming organic compounds, nutrients, gases, particulates, heavy metals, hazardous chemicals, pathogenic organisms, etc.

• The harm caused by the pollutants to both humans and other living organisms include diseases in humans and animals, reduced amount of nutrients in the soil, intake of toxic substances, breathing difficulties, etc.


END


Documents

UGRC 144 Science and Technology in Our Lives/Geohazards · •Air pollutants can be natural or human-produced, and they could be primary or secondary in origin. •Primary pollutants