Presentation on theme: "Water Pollution: How clean is your water?"— Presentation transcript:
1Water Pollution: How clean is your water? Chapter 22 By Lakshmi
2Read wastewater treatment system in Arcata, California and list the effective use of the system followed in Arcata.
3What is water pollution? Any physical, biological or chemical change in water quality that adversely affects living organisms or makes the water unsuitable for desired usesTwo Major CategoriesPoint source pollutionNon-point source pollution
4Can you give some examples? Non-point source pollutionPoint source pollution
5Point Source pollution Water pollution that can be traced to a specific origin. It is discharged into the environment through pipes, sewers, or ditches from specific sites such as factories or sewage treatment plants.A cyanide spill contaminated the Tisza and Danube rivers in Europe in 2000, killing millions of fishes and shutting off downstream water supplies.
6Nonpoint source pollution It is also called polluted runoff, and is caused by land pollutants that enter bodies of water over large areas rather than at a single point. It occurs when precipitation moves over and through the soil, picking up and carrying away pollutants that eventually are deposited in lakes, rivers, wetlands, groundwater, estuaries, and the ocean.It includes agricultural run off(such as fertilizers, pesticides, livestock wastes, and salt from irrigation), mining wastes, municipal wastes, and construction sediments. Soil erosion, logging operations, eroding stream banks, and construction sites is a major cause of nonpoint source pollution.
7Eight categories of water pollutants The main water pollution issue is lack of disease-free drinking water. water pollutants are divided into eight categories:SewageDisease causing agentsSediment pollutionInorganic plant and algal nutrientsOrganic compoundsInorganic chemicalsRadioactive substancesThermal pollution.
8Pollution problems caused by Sewage Carries disease-causing agents and poses a threat to public health.Causes two environmental problemsA) enrichment and b) oxygen demandEnrichment is by the addition of high levels of plant and algal nutrients such as nitrogen and phosphorus.Decomposition of the sewage requires oxygen and use up most of the dissolved oxygen, leaving little for fishes and other aquatic organisms. At extremely low oxygen levels, fishes and other animals leave or die.
9Sewage and BODBiochemical oxygen demand (BOD), or biological oxygen demand is usually expressed as milligrams of dissolved oxygen per liter of water for a specific number of days at a given temperature.A large amount of sewage in water generates a high BOD, which robs the water of dissolved oxygen.When dissolved oxygen levels are low, anaerobic microorganisms produce compounds with unpleasant odors, further deteriorating water quality.
10EutrophicationEutrophication is a natural process that increases the nutrient load of lakes over time as sediment washes into themArtificial or cultural eutrophication is when human activities speed up this process
11Eutrophication: An Enrichment Problem Lakes, estuaries, and slo-flowing streams that have minimal levels of nutrients are unenriched or oligotrophic. Such lakes have clear water and support small populations of aquatic organisms.Eutrophication is the enrichment of a lake, estuary by inorganic plant and algal nutrients such as phosphorus, and such a water body is said to be eutrophic. This increases photosynthetic productivity.
17Next step…When the algae die, they sink to the lake bottom to be eaten by decomposers. Decomposers deplete oxygen and create Hypoxia (low oxygen levels) or Apoxia (no oxygen).This kills the organisms in the water and creates a “dead” zoneWhat can be done? Aerate the water, like the fountains in our lakes and Glenwood Lake
18Disease causing Agents Municipal wastewater usually contains many bacteria, viruses, protozoa, parasitic worms that cause human or animal diseases.In the year 1993, a microorganism (Cryptosporidium) contaminated the water supply in the greater Milwaukee area. About 370,000 developed diarrhea, making it the largest outbreak of a waterborne disease ever recorded in the United States.In 2000, the first waterborne outbreak in North America of the deadly strain of Escherichia coli occurred in an Ontario town (Walkerton) in Canada.
19Disease-causing Agents Infectious organisms that cause diseasesOriginate in the wastes of infected individualsCommon bacterial or viral diseases:Typhoid, cholera, bacterial dysentery, polio, and infectious hepatitis
20Some human diseases Transmitted by Polluted water Infectious AgentType of organismMajor symptomsCholeraVibrio choleraeBacteriumSevere diarrhea, vomitingDysenteryShigella dysenteriaeInfection of the colon causes painful diarrhea with mucus and blood in the stoolsEnteritisClostridium perfringensInflammation in the small intestine causes general discomfort, loss of appetite, and diarrhea.TyphoidSalmonella typhibacteriumHeadache, fever, followed by rash and sometimes with hemorrhaging in the intestinesInfectious hepatitisHepatitis virus AVirusInflammationof liver causes jaundice, fever, nausea.
21Human diseases contd..Cryptosporidiosis caused by Cryptosprodium sp a protozoan. Symptoms include diarrhea and cramps.Amoebic dysentry caused by Entamoeba histolytica, a protozoan. Symptoms: infection of the colon causes painful diarrhea with mucus and blood in the stools.Schistosomiasis caused by Schistoma sp. a fluke. It is a tropical disorder of the liver and bladder causes blood in urine, diarrhea, abdominal pains.Ancylostomiasis caused by hookworm. Symptoms are anemia and bronchitis.
22Effects of Sewage on Human Health Untreated or raw sewage can transmit disease such as cholera, dysentery and typhoidAbout 4 billion cases of diarrhea per year cause 1.8 million deaths, over 90 per cent of them (1.6 million) among children under five (data from UNICEF, 2010)Famous Case of Typhoid MaryYou can make use of the above link to know about the famous case of Typhoid Mary
23Effects of Sewage on Ecosystems As sewage is eaten by decomposers, it reduces the dissolved oxygen (D.O.) content of the water.All aquatic species have a range of tolerance for D.O. and if the level is too low, they die. This can result in fish kills.
24Dissolved Oxygen Levels Healthy water has a high level of dissolved oxygen (> 8ppm)Oxygen-poor water (<2ppm) only supports detritivoresOxygen is added to the water by diffusion from air (affect of temperature) and photosynthesisOxygen is removed by respiration of plants and animalsThe addition of sewage and wastes stimulates oxygen consumption by detritivores
25How do you know if water is safe to swim in? A test called the fecal coliform test tests for E. Coli bacteria present in feces.one colony of bacteria per 100ml or greater is considered unsafe to drinkSafe swimming water should have no more than 200 per 100 mL of waterRecreational water should have nor more than 2000 per 100 mL of water.Raw sewage may contain several million coliform bacteria per 100 mL of waterA good rule to follow: don’t go to the beach after it rains
26Disease-causing Agents Monitored by testing for presence of E. coli in the water via a fecal coliform testIndicates the presence of pathogenic organisms
27Monitoring for sewageBacterial source tracking (BST) attempts to make the proper identification. It has successfully identified the source of coliform bacteria in several cases.
28Sediment and suspended solids Largest pollutant by volume in most parts of world25 billion metric tons of topsoil from runoff and erosion50 billion from grazing, construction etc.Erosion of agricultural lands, forest soils exposed by logging, degraded stream banks, overgrazed rangelands, strip mines…
29Effects of sediment pollution Reduces light penetration, covers aquatic organisms, brings insoluble toxic pollutants into the water, and fills in waterways.Makes the water turbid, which inturn decreases the light penetration.This in turn reduces productivity.Extreme turbidity reduces the number of photosynthetic organisms which in turn results in decrease in number of consumers.Sediments can clog gills of organismsAdversely affect water quality by carrying toxic chemicals.Disease causing agents are also transported into water via sediments.
30Inorganic Plant and Algal Nutrients Chemicals such as nitrogen and phosphorus that stimulate the growth of plants and algaeHarmful in large concentrationsSources:Human and animal wastes, plant residues, atmospheric deposition, and fertilizer runoffCauses:Enrichment, red tides, bad odors,a high BOD, “dead zones”
31Red TideWhen some pigmented marine algae experience explosions or blooms, their great abundance colors the water orange, red, or brown.Some of the algal species that form red tides produce toxins that attack the nervous systems of fishes leading to massive fish kills.Water birds like cormorants which eat the contaminated fish die.The toxins work their way up the food web to marine mammals and people.
32Red tide (Read more on Red Tide Page number 512)
33The Dead Zone in the Gulf of Mexico Every spring and summer, fertilizer runoff from midwestern fields andmanure runoff from livestcok operations in states such as Iowa, Wisconsin,Illinois, find their way into the Mississippi River and from there into theGulf of Mexico.Other than bacteria no lifeExists in the Dead Zone. TheWater does not have enoughDissolved oxygen. This oxygen-Free condition is known asHypoxia, when algae grow rapidlyAnd are decomposed.
34What do we do?Reduce nitrogen runoff coming down the Mississippi River.Modify farming methods so that less fertilizer is needed.Reduce phosphorus as well.Sewage treatment plants and airborne nitrogen oxides from automobile emissions to be addressed.Restoring former wetlands will retain nutrients such as nitrogen and phosphorus.
35Organic ChemicalsPesticides, oils, plastics, pharmaceuticals, pigments, detergents, cleaning solutions, and paintsSome are carcinogenic and some act as endocrine disruptors and cause hormonal effects.Alternative organic compounds which are less toxic and degrade more readily so that they are not persistent in the environment can be developed.Tertiary water treatment effectively eliminates many synthetic organic compounds in water.(Page 514-List of synthetic organic compounds found in polluted water)
36Organic compounds Chemicals that contain carbon atoms Natural examples: sugars, amino acids, and oilsHuman-made examples: pesticides, solvents, industrial chemicals, and plasticsHuman examples are more common
37Toxic Inorganic materials Heavy metals:mercury, lead, cadmium and nickelmining wastes, mine drainageArsenic in ground water
38LeadSource – lead based paint, lead containing anti-knock agents in gasoline.Effects : develop hypertension.High levels of lead in pregnant women increase the risk of miscarriages, premature deliveries and stillbirths.Children will suffer from a variety of mental and physical impairments, including hearing loss, attention deficit, lowered IQ, and learning disabilities.Lead accumulates in bone.
39MercurySource: coal-fired power plants release the largest amount of mercury.Municipal waste and medical waste incinerators also release mercury. Fluorescent lights and thermostats are examples of municipal wastes that contain mercury, whereas thermometers and blood pressure cuffs are examples of medical waste.Smelting of metals such as lead, copper, and zinc.Mercury is used in the chemical plants that manufacture chlorine and caustic soda. Some of the mercury vaporizes and enters the atmosphere.
40Contd..Once mercury enters a body of water it settles into the sediments where bacteria converts it to methyl mercury compounds, a more toxic form that enters food web. (biomagnification occurs)Exposure to methyl mercury causes kidney disorders and damages the nervous and cardiovascular systems.The exposure of the developing fetuses to mercury is linked to diminished cognitive function, cerebral palsy, and developmental delays.Low levels caues headache, depression.
41Radioactive Substances Contain atoms of unstable isotopes that spontaneously emit radiationSourcesMiningProcessing radioactivematerialsNuclear power plantsNatural sources
42Effects of thermal pollution Less oxygen dissolves in warm water than in cold water. when the level of dissolved oxygen is lowered due to thermal pollution, a fish ventilates its gills frequently and puts a great deal of stress on the fish.It also affects the reproductive cycle, digestion rates, and respiratory rates.At warmer temperature fishes require more food to maintain body weight.In extreme themral pollution they die.
43Thermal PollutionWater temperatures are usually stable so organisms are poorly adapted to rapid changeoxygen solubility decreases as temperature increasesmost happens in industrial coolingPower plants release warmed water into rivers