hygiene department, college of basic medical sciences, dalian medical university © 2006 1 chapter 3...

Hygiene Department, College of Basic Medical Sciences, Dalian Medical University © 2006 1

Chapter 3 Water and SoilChapter 3 Water and Soil


The Earth’s WaterThe Earth’s Water

80 percent of Earth’s surface is covered with water

97% of the earth’s water is salt water (oceans)

3% of the earth’s water is fresh water (rivers, lakes,

streams)

Only 1% of the fresh water is available for our use

The available fresh water amounts to a generous supply

that is continuously collected, purified, recycled, and

distributed in the solar-powered hydrologic cycle

Distribution of Water ReservoirsDistribution of Water Reservoirs

Oceans 97%

Atmosphere 0.01%

Rivers, Lakes, and Inland Seas

0.141%Soil Moisture 0.0012%

Ground Water 0.4 – 1.7%

Ice Caps and Glaciers 1.725%


Global Total Water and Freshwater Reserves Global Total Water and Freshwater Reserves


The Water CycleThe Water Cycle


Groundwater

• Available at point of need at little cost

Surface water

• Usually requires extensive purification

Ocean and brackish waters

• Costly to desalinate

Sources of FreshwaterSources of Freshwater


Body composition

• Body, 65% water; blood, 83%; bones, 25%

• Water loss: 1% thirst; 5% hallucinations; 15% death

Basic requirements for safe water

• Drinking: 2–3 liters/day

• Minimum acceptable standard for living (WHO)

--20–50 liters/day for cooking and basic hygiene

Freshwater FactsFreshwater Facts


Vulnerability of surface water to:• Drought (not replenished); i.e., lakes, reservoirs• Diversion of rivers for agricultural and urban use

Declining groundwater levels• Failure to replenish• Compaction of aquifers• Saltwater intrusion

Surface water pollution from nonpoint sourcesGroundwater pollutionIncreasing competition for water supplies

• World’s available freshwater is not distributed evenly

Current Water IssuesCurrent Water Issues


U.S. Water Consumption and Population Growth RatesU.S. Water Consumption and Population Growth Rates


Water is essential to life Our health depends on the quality and safety of water Every 8 seconds a child dies of water-related disease 5 million per year die of illnesses linked to

• Unsafe drinking water• Unclean domestic environments, and • Improper excreta disposal

Nearly ¼ of humanity remains without proper access to water and sanitation

Water pollution and poor water resources are the big problem in China. There are 700 million people in China, whose drinking water is not safe.

Water/Health FactsWater/Health Facts


Effects of Water ShortagesEffects of Water Shortages

• 40% of the world’s population are now facing the

experience of water shortages

• By 2025 at least 3 billion people in 90 countries are

expected to face severe water stress

• Threaten their agriculture and industry and the health of

their people


The last drop of water------ Human’s tear


Water Pollution


What is Water PollutionWhat is Water Pollution

• Definition: Any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses.

• A natural indicator of water pollution is the presence of coliform bacteria. 0 colonies is recommended, and 200 colonies per 100 milliliters is the maximum recommended level

• Most water pollutants are sediment and suspended matter. These consist of soil and solids eroded from land


Because of the water pollution……Because of the water pollution……

Today’s Dying WaterToday’s Dying Water

Child and Dying Fish Dying Duck by Oil Spill

Dying Ocean because of dumping and floating waste


For WaterFor Water

Make a choice, where do you want to live?Unfortunately, today’s water looks more like in the right picture.

Also, water condition is becoming even worse than ever.

What are causes of water pollution?What do we have to do for saving our water?


Sources of Water Pollution


Point SourcesPoint Sources

Pollution is discharged from a single point

These sources discharge pollutants at specific locations through pipes, ditches, or sewers into bodies of water.

Point Pollution is relatively easy to regulate, although not as easy to enforce.

Ex. Factories, sewage treatment plants, active and abandoned mines, off-shore oil wells, and oil tankers


Sources of Point PollutionSources of Point Pollution


Nonpoint SourcesNonpoint Sources

They are diffused across a broad area and their contamination cannot be traced to a single discharge point. usually large land areas that pollute water by runoff, subsurface flow, or depletion from the atmosphere

These pollutants including:– Excess fertilizers, herbicides, and insecticides from

agricultural lands and residential areas;– Oil, grease, and toxic chemicals from urban runoff and

energy production;– Sediment from improperly managed construction sites,

crop and forest lands, and eroding streambanks;– Salt from irrigation practices and acid drainage from

abandoned mines;– Bacteria and nutrients from livestock, pet wastes, and faulty

septic systems


Nonpoint SourcesNonpoint Sources


Nonpoint-source pollutionNonpoint-source pollution

• Runoff!!

• Nonpoint source pollution can enter the water system from many different ways and is more difficult to control.

• 96% of water pollution is nonpoint source.


Sources of Nonpoint PollutionSources of Nonpoint Pollution


Types of Water Pollution


Classes of Water PollutantsClasses of Water Pollutants


Major Causes of Stream and River PollutionMajor Causes of Stream and River Pollution


Typical Contaminants Found in Raw WaterTypical Contaminants Found in Raw Water


More Typical Contaminants Found in Raw WaterMore Typical Contaminants Found in Raw Water


Types of Water PollutionTypes of Water Pollution

Inorganic chemicals and minerals Synthetic organic compounds Oxygen-demanding wastes Diseases-causing agents Thermal pollution Sediments Oil


Heavy metal (cadmium, chromium, lead, mercury, copper, etc.), Cyanide, ammonia, hydrogen sulfide, etc.

Toxic substances (arsenic, fluoride, etc) Sources:

• Industrial discharges, like bleaching and dyeing, gold milling • Marine sediments

Toxic effects (direct or long term) • Cancer• Nervous system damage• Harms aquatic life• Lowers crop yields• Corrosion of metals • Odour

Inorganic chemicals and mineralsInorganic chemicals and minerals


Pesticides, gasoline, oil, plastics, solvents, detergents, PCBs, paints, DDT, etc.

Sources: • Domestic sewage, agricultural, industrial and commercial

operations, etc. Certain chemicals, including PCBs, dioxin, and DDT, are very

poisonous and non-biodegradable. They are resistant to biological breakdown and persist and accumulate in the environment

Toxic effects (threaten human and aquatic life)• Cancer• Nervous system damage• Directly toxic to aquatic life• Causing odours

Synthetic Organic CompoundsSynthetic Organic Compounds


PesticidesPesticides

During raining, flow into river or lake, cause immediate toxic effects on aquatic life or may accumulate along the food chain until a toxic level is reached

Toxic non-biodegradable Soluble in fat DDT was previously used and banned in many parts

of the world


• The detergents forms a foamy layer on the surface that reduces the penetration of light and the dissolution of oxygen.

• They also contain high phosphate content.

• It will causes algae bloom.

DetergentsDetergents


Water-soluble phosphates, nitrates, potassium, etc.

Sources:• Fertilizers application in farming

• Sewage treatment plant effluents

Cause overgrowth of algae which leads to the

depletion of dissolved oxygen and the death of fish

( eutrophication and algal blooming)

Plant nutrientsPlant nutrients


DetergentsDetergents

• Excessive plant growth

• Depletion of oxygen in water

• Fish kills


All organic materials and wastes that can be decomposed by aerobic bacteria

It degrade water quality by depleting water of dissolved oxygen Sources

• Sewage from domestic and animals sources • Industrial wastes from food processing, papermills, tanning

operations, meatpacking plants, etc• Decay of dead plant and animals

Broken down or decomposed by bacterial and other biological activity (biodegradation)

• It consumes oxygen (oxygen demanding)• It causes oxygen depletion in water

Oxygen-Demanding WastesOxygen-Demanding Wastes


Oxygen in WaterOxygen in Water

Importance of oxygen in water– Basic requirement of almost all plant and

animal life-forms in water body except for some anaerobic organisms

– Insufficient amount of oxygen Bacteria will use up oxygen in the water. damaging the ecosystem by killing other aerobic organisms

What else can affect the amount of O2 in the water– Temperature– Speed of water flow– Roughness of surface over which water flows


Pathogenic microorganisms • Bacteria (E. coli with diarrhea, fecal coliform and

pathogens)• Viruses (hepatitis outbreaks, meningitis)• Protozoa (Giardia and cryptosporidium causing diarrhea,

cramps and fatigue)• Parasitic worms (Tapeworms and roundworms – children)

Sources:• sewage and untreated waste from human and other

animals (hosts) Spread diseases through drinking water consumption or

through other water contact activities

Disease-Causing AgentsDisease-Causing Agents


Caused by the heat absorbed by the water used to cool industrial and power plants

Sources:• Industrial and commercial operations• Power plants

Heating up the aquatic environment• Aquatic organisms may become physiologically stressed or

even be killed• Interference of the natural life processes, e.g. reproduction,

growth rates, distribution of species• Decreasing dissolved oxygen (DO) in water

Thermal PollutionThermal Pollution


Release of weathered sediments through runoff to water bodies; Ex. Insoluble particles of soil and other solids

Sources:• Clearing and developments adjacent to water bodies• Natural weathering of soils• Sewage discharge• Littering in water bodies

Effects• Directly smother and kill aquatic life• Directly destroy habitats and spawning areas• Reduce the sunlight penetrating into water, reduce

photosynthesis.

SedimentsSediments


Caused by accidental spillage or illegal washings from oil tankers or seeping from ships (crude oil, petroleum, gasoline, etc)

Sources:• Wastewater discharges,

leaching,• Recreational boating, • Underground tank leakage

Oil PollutionOil Pollution


• Oil covering the water surface prevent oxygen from dissolving in water

• Oil soaked on the feathers of the sea birds prevents them from flying. It also reduce their insulating property to cause them die of clod.


The crude oil kills marine living things

like fish-eating birds by suffocation .

Destroys food chain

The shading may restrict light

penetration and reduce photosynthesis

of marine plant.

Destroys scenery

The effects caused by oil pollutionThe effects caused by oil pollution


Ocean PollutionOcean Pollution

• Pollution of the ocean is a major concern. All water flows into the ocean, so runoff is a major problem.

• Each year about 37 million gallons of oil are spilled into the ocean by tanker accidents.

• Runoff is responsible for 200-300 million gallons a year.


A special case: GroundwaterA special case: Groundwater

• What forms of pollution can affect groundwater• All of them except thermal pollution!• Renewal time of groundwater is important

– Rivers: 12-20 days– Soil Moisture: 280 days– Groundwater: 300 years


Ground Water PollutionGround Water Pollution

• Pollutants are filtered as they travel through the permeable soil

• BUT: not all pollutants are removed. The rest find their way into the aquifers. A threat is now posed by an ever-increasing number of soluble chemicals from urban and industrial activities and from modern agricultural practices.


Sources of Groundwater ContaminationSources of Groundwater Contamination


Point and nonpoint sources of surface water contamination

Surface Water ContaminationSurface Water Contamination


Pollution in LakesPollution in Lakes

• They receive inputs of nutrients and silt from the surrounding land as a result of natural erosion and runoff.

• Human activities accelerate the input of nutrients- a process called cultural eutrophication

• Increase in nitrate- and phosphate-containing effluents from sewage treatment plants, fertilizer and waste runoff, and erosion.


What is EutrophicationWhat is Eutrophication

It means “well fed”: Nutrients such as nitrates and phosphates (from organic matter

such as fertilizers, manure) enter the water body algae growth is stimulated some algae release toxins and result in fish deaths. Also, algae start dying and settle at the bottom. Decomposing bacteria decompose the algae. As bacterial population explodes (especially in warmer

temperatures), oxygen supply in the water decreases. Eventually decomposing becomes anaerobic and foul smell

results. Fish and plants are deprived of oxygen (hypoxia) and die off.


Cultural EutrophicationCultural Eutrophication

Discharge of untreatedDischarge of untreatedmunicipal sewagemunicipal sewage

(nitrates and phosphates)(nitrates and phosphates)

Nitrogen Nitrogen compoundscompounds

produced by carsproduced by carsand factoriesand factories

Discharge of treatedDischarge of treatedmunicipal sewagemunicipal sewage

(primary and secondary(primary and secondarytreatment:treatment:

nitrates and phosphates)nitrates and phosphates)

Discharge of Discharge of detergentsdetergents

( phosphates)( phosphates)

Natural runoffNatural runoff(nitrates and(nitrates andphosphatesphosphates

Manure runoffManure runoffFrom feedlotsFrom feedlots(nitrates and(nitrates andPhosphates,Phosphates,

ammonia)ammonia)

Dissolving of Dissolving of nitrogen oxidesnitrogen oxides

(from internal combustion(from internal combustionengines and furnaces)engines and furnaces)

Runoff and erosionRunoff and erosion(from(from cultivation,cultivation,

mining, construction,mining, construction,and poor land use)and poor land use)

Runoff from streets,Runoff from streets,lawns, and constructionlawns, and construction

lots (nitrates andlots (nitrates andphosphates)phosphates)

Lake ecosystemLake ecosystemnutrient overloadnutrient overload

and breakdown ofand breakdown of chemical cyclingchemical cycling


Surface water quality in lakes and riversSurface water quality in lakes and rivers

EutrophicationEutrophication


Preventing Lake PollutionPreventing Lake Pollution

• Advanced waste treatment• Bans or limits on phosphates in household detergents• Soil conservation• Land –use control to reduce nutrient runoff• Bans on certain pesticides


Lake Cleanup MethodsLake Cleanup Methods

• Dredging bottom sediments

• Removing excess weed

• Controlling undesirable plant growth with herbicides and algicides

• Pumping air through lakes and reservoirs to avoid oxygen depletion

• Remove excess nutrient buildup

IndustryNitrogen oxides from autosand smokestacks; toxicchemicals, and heavymetals in effluents flowinto bays and estuaries.

CitiesToxic metals andoil from streets andparking lots pollutewaters; sewageadds nitrogen andphosphorus.

Urban sprawlBacteria andviruses from sewersand septic tankscontaminate shellfishbeds and closebeaches; runoffof fertilization fromlawns adds nitrogenand phosphorus.

Construction sitesSediments are washed into waterways,choking fish and plants, cloudingwaters, and blocking sunlight.

FarmsRun off of pesticides, manure, andfertilizers adds toxins and excessnitrogen and phosphorus.

Red tidesExcess nitrogen causes explosivegrowth of toxic microscopic algae,poisoning fish and marine mammals.

Healthy zoneClear, oxygen-rich waterspromote growth of planktonand sea grasses, and support fish.

Oxygen-depleted zoneSedimentation and algaeovergrowth reduce sunlight,kill beneficial sea grasses,use up oxygen, and degrade habitat.

Toxic sedimentsChemicals and toxic metalscontaminate shellfish beds,kill spawning fish, andaccumulate in the tissuesof bottom feeders.

Closed shellfish bedsClosed

beach Oxygen-depletedzone


Effects of Water Pollution


• Human and animal fecal wastes• Domestic waste water• Waste water of agriculture and industry

Waterborne DiseasesWaterborne DiseasesSources of waterborne pathogens

Pathogenic MicroorganismsPathogenic Microorganisms• Bacteria

– Typhoid fever, Cholera, Shigella (dysentery), Salmonella• Viruses

– Hepatitis A, poliomyelitis and Rotavirus– Are resistant to disinfection by chlorination

• Protozoans– Giardia Lambia, Cryptosporidium, amoebic dysentery.– Are resistant to desinfection by chlorination.


Classification of water-related illnessesClassification of water-related illnesses


Epidemic Characteristics of Waterborne DiseasesEpidemic Characteristics of Waterborne Diseases

Outbreak prevalence when water contaminated by a lot of pathogenic bacteria at one time

Cases happened continuously all the year round when water is contaminated frequently

Incidence is in accord with water supply and distribution

Epidemic can be controlled after water treatment


Chemical Contaminants in Drinking WaterChemical Contaminants in Drinking Water

Nitrates– Sources: from fertilizers or septic tanks – Example: “blue babies” methhemoglobinemia

Mercury– Sources: Natural occurrence; Man-made sources – Example: Minamata-disease

Arsenic– Sources: Natural occurrence– Example: Endemic arsenicosis

Fluoride– Sources: air; water; soil; living organisms – Example: Endemic fluorosis


NitrateNitrate

Sources

industrial and domestic wastewater

Runoff from fertilizer use

natural environment


nitrate nitritenitrite

nitrite nitrosaminenitrosamine

amine

Nitrate in natural environment or in vivo in GI tract


Potential Health EffectsPotential Health Effects

Nitrate concentrations ( > 10 mg/L NO3-) may cause

Methemoglobinemia (Blue Baby Syndrome) in infants

The toxicity of nitrate in humans is a result of the

reduction of nitrate (NO3-) to nitrite nitrite (NO2

-)

By reacting with hemoglobin, nitrite forms methemoglobinmethemoglobin

(MHb), a substance that does not bind and transport

oxygen to tissues. Thus, methemoglobin formation may

lead to asphyxia


Mercury Mercury

Minamata Disease

In the 1950s, industries around Minamata Bay in Japan discharged so much mercury into the bay that people were poisoned by mercury that had found its way into the local seafood.


Mercury (Hg) and the environmentMercury (Hg) and the environment

Mercury—its properties

Natural occurrence

Man-made sources


Physical and chemical properties of mercuryPhysical and chemical properties of mercury

A heavy, silver white liquid at ambient temperature (density 13.5g/ml)

A long liquid range of 396 (Melting point 38.89 ℃; Boiling point 357.25 )℃ ℃

Low electrical resistivity--- one of the best metallic electrical conductors

Highest volatility of any metal Formation of amalgams (alloys) with silver and tin

for dental fillings


Natural occurrenceNatural occurrence

Degassing of the earth’s crust

Emission from volcanoes

Evaporation from natural bodies of water


The uses of mercury by manThe uses of mercury by man

Chlor-alkali industry

Electric industry

Dental amalgam fillings

Gold extraction

Paint

Agriculture

Pharmaceuticals


The biological impactsThe biological impacts

Mercury amplification in Food-Chain

• Methylmercury compounds are amplified by

common food-chain, including man’s

Biologically methylated mercury can be converted

non-enzymically or through microbial action into

highly toxic methymercury


Rainbow smelt1.04 ppm

Zooplankton0.123 ppm

Phytoplankton0.0025 ppm

Water0.000002 ppm

Herring gull124 ppm

Lake trout4.83 ppm

Herring gull eggs124 ppm


Epidemics of Mercury PoisoningEpidemics of Mercury Poisoning


Main Symptoms of Methymercury PoisoningMain Symptoms of Methymercury Poisoning

Methylmercury is neurotoxic to man. Clinically, diverse nervous signs and symptoms are manifest with high frequency.

Sensory disorders

Ataxia

Impairment of hearing

Constriction of the visual field

Central disequilibrium


Fetal type of methylmercury poisoning is said to be far more serious than adult type.

In the fetal type of this disease, cerebral infantile paralysis like symptoms are observed, such as mental retardation, retardation in development of speech, mastication, salivation and swallowing, and disturbances body morbidity

Congenital Methylmercury PoisoningCongenital Methylmercury Poisoning

Congenital methymercury poisoning


FluorideFluorideFluorides are organic and inorganic compounds

containing the fluorine element. Only inorganic fluorides are the focus

Fluoride in water is dependent on • source of water• type of geological formation • amount of rainfall

Surface waters generally have low fluoride while ground waters may have high concentrations of fluoride as has been found in many parts of the world.

It occurs in humans as dental and skeletal fluorosis


chalkiness of teeth brown stain on teeth

brown wavy striations on teeth severe mottling

Symptoms of Dental fluorosis Symptoms of Dental fluorosis


Symptoms of Skeletal Fluorosis Symptoms of Skeletal Fluorosis A 30-year old adult affected by skeletal fluorosis with stiff neck and vertebral column. He has to turn his whole body sideways to see someone there; and has to lie on bed to see an airplane


Arsenic is a semi-metal element in the periodic table. It is

odorless and tasteless

Arsenicosis is an endemic disorder caused mainly by drinking

water having an arsenic content ranging from 10-50 g/l

The symptoms of arsenicosis are seen more commonly in

hands, feet and chest and include spotted melanosis, lesions

and keratosis, and skin cancer (Bowens carcinoma)

ArsenicArsenic

Pigmentation and depigmentation

Melanosis on hand Keratosis on feet

Skin cancer (Bowens carcinoma)

Symptoms of ArsenicosisSymptoms of Arsenicosis


Blackfoot disease (BFD) is a severe form of peripheral

vascular disease (PVD), in which the blood vessels in

the lower limbs are severely damaged, resulting

eventually in progressive gangrene. It has been

observed in Taiwan.

It is caused by arsenic poisoning

Blackfoot DiseaseBlackfoot Disease


Health Effects of Other Chemicals in Drinking Water Health Effects of Other Chemicals in Drinking Water

Asbestos• lung disease; cancer

Cadmium • kidney, liver, bone and blood damage

Chromium • damage to liver, kidney circulatory and nerve

tissues; skin irritation Lead

• stroke and kidney disease; cancer Copper

• gastrointestinal disturbance ; liver or kidney damage


Cyanide• weight loss, thyroid effects, nerve damage

Thallium • changes in blood chemistry; damage to liver, kidney,

intestinal and testicular tissues; hair loss Selenium

• hair and fingernail loss; damage to kidney and liver tissue, and the nervous and circulatory systems

Volatile Organic Chemicals (VOCs) • cancer; liver and kidney damage

Dioxin • a variety of reproductive effects, from reduced fertility

to birth defects; cancer

Health Effects of Other Chemicals in Drinking Water Health Effects of Other Chemicals in Drinking Water


Water Treatment


Simplified Flowchart of Drinking Water TreatmentSimplified Flowchart of Drinking Water Treatment


Must destroy bacteria, viruses in water within a

reasonable time despite all variations in water

temperature, composition, and concentration of

contaminants

Must not be toxic for humans and domestic animals,

unpalatable, or otherwise objectionable

Water Disinfection RequirementsWater Disinfection Requirements


Must be reasonable in cost and safe and easy to store,

transport, handle, and apply

Residual concentration in the treated water must be

easily and, preferably, automatically determinable

Must be sufficiently persistent so that the

disappearance of the residual would be a warning of

contamination

Water Disinfection RequirementsWater Disinfection Requirements


ChlorineChlorine


The Shortcomings of ChlorineThe Shortcomings of Chlorine


Chlorination has the potential of reacting with some organic compounds present in the water supply to create trihalomethanes (THM; chloroform)

Surface water supplies, high in dissolved natural organic material (humics), are especially vulnerable to THM formation

Chlorine Reaction ProductsChlorine Reaction Products

When free chlorine is the disinfectant, THM levels are generally higher in communities using rivers and treams as their source of drinking water than in communities using wells

THMs are potentially carcinogenic


Activities Permitted for Various Coliform LevelsActivities Permitted for Various Coliform Levels

ConclusionConclusion


Soil Pollution Soil Pollution

• The introduction of substances, biological organisms, or energy into the soil, resulting in a change of the soil quality, which is likely to affect the normal use of the soil or endangering public health and the living environment.


• Soil contaminants are spilled onto the surface through many different activities.

• Most of these are the result of accidents involving the vehicles that are transporting waste material from the site at which it originated to the site at which it is to be disposed.


• Others involve accidents involving vehicles (automobiles, trucks and airplanes) not transporting wastes, but carrying materials, including fuel, that when spilled contaminate the soil.


• Still other spills are the direct action of humans pouring potentially toxic materials (solvents, paints, household cleaning agents, etc.) onto the ground surface rather than disposing these materials by more appropriate means.


Pollutant on surface of soilPollutant on surface of soil

• When any liquid pollutant is on or just below the ground surface for any period of time, one of three things could happen to it, if it is not cleaned up first.


pollutant might be washed away by precipitation, causing little or no harm to the ground on which it was found ( however, pollutants will simply accumulate somewhere else)

the pollutant, if volatile, could evaporate, again causing little harm to the soil ( however, not a solution to the bigger pollution problem, as it might become a source of air pollution).

pollutant could infiltrate through the unsaturated soil, in much the same way as ground water.

Pollutant on surface of soilPollutant on surface of soil

hygiene department, college of basic medical sciences, dalian medical university © 2006 1 chapter 3...

Documents

earths water

water consumption

ground water

safety of water

water blood

water loss

water cycle slide

dalian medical university