2 Part 6: Water PollutionPoint source pollution - source is from drain pipes, ditches, sewer outfalls, factories and power plants - easy to monitor and regulateNonpoint source pollution - runoff from farm fields and feedlots, lawns and gardens, golf courses, construction sites, atmospheric deposits - no specific location so harder to monitor and regulateWater pollution is defined as any physical, biological, or chemical change in water quality that adversely affects living organisms. There are many different potential sources of water pollution, but commonly all sources are divided into two distinctive types: 1) point source pollution is where water is collected into a single place before being discharged; and, 2) nonpoint source pollution is where pollution has a scattered or diffuse source (from an area rather than a single point). Urban pavement and rooftop runoff during storms are examples of non-point source pollution.One of the major advantages associated with controlling point source pollution is that typically a single entity can be identified as its source; thus, efforts at water pollution control have been very successful in cleaning up point sources of pollution. In the 60's, Lake Washington was cleared of point-source pollution (mostly sewage), but today it is suffering from non-point source (urban runoff) pollution. Usually, nonpoint source pollution is a harder problem to fix compared to a nonpoint source problem such as that of Lake Washington in the 60's.
3 Types and Results of Water Pollution Infectious agents - 25 million deaths a yearOrganic materials - biological oxygen demand (BOD) increase resulting in oxygen sagPlant nutrients - eutrophication, toxic tidesMetals - mercury and lead poisoningNonmetallic salts - poison seeps and springsAcids and bases - ecosystem destabilizationOrganic chemicals - birth defects, cancerSediments - clogged estuaries, death of coral reefsThermal pollution - thermal plumeThe actual agents of water pollution are numerous, including biologically infectious materials, organic materials whose effect is primarily through the reduction of dissolved oxygen and water (termed biological oxygen demand or BOD), plant nutrients that can lead to excess biological growth, toxic metals such as lead and mercury, acids and bases, toxic organic compounds, eroded sediment material that can clog waterways, and heat, which can change the nature of biological systems.As a trout fisherman, for instance, I know that trout prefer cold, highly oxygenated water. When thermal pollution or excess BOD is introduced into a stream, typically other species of fish (such as bass or even carp in extreme cases) replace the trout,.
4 Infectious AgentsMain source of waterborne pathogens is untreated or improperly treated human waste.Animal wastes from feedlots and fields is also an important source of pathogens.In developed countries, sewage treatment plants and pollution-control devices have greatly reduced pathogens.Tests for water quality are done for coliform bacteria (intestinal bacteria). Such tests are easy and cheap.Escherichia coli (E. coli) is the major coliform bacterium speciesWhenever coliform (intestinal) bacteria are present in high concentrations, other more pathogenic microorganisms are also present. A relatively quick and inexpensive method of testing for these organisms is to use a serial dilution of a known quantity from water collected from the site of interest. After incubating the tubes, the diluted samples can be plated on a petri dish with agar and the number of colonies that result can be used to calculate the original concentration of coliform bacteria. Presumably, each colony was originally derived from a single bacterium cell.
5 Environmental Implications of Oxygen-Demanding Wastes Oxygen – the life-giving gasadded to water by diffusion from wind and waves, and by photosynthesis from green plants, algae, and cyanobacteria.removed from water by respiration and oxygen-consuming processes.Water with a Dissolved Oxygen Content (DOC) content > 6 parts per million (ppm) supports desirable aquatic lifeWater with < 2 ppm oxygen supports mainly detritivores and decomposers.The next slide summarizes the detailed text for this slide. Read this slide first and then see if you can explain what the figure on the following slide is depicting. Oxygen sag refers to the shape of the dissolved oxygen curve downstream from the point source of pollution (it sags and then slowly comes back).
6 Biochemical Oxygen Demand (BOD) - the amount of dissolved oxygen consumed by aquatic microorganisms in respiration.When organic wastes are added to rivers, microorganisms use more oxygen in consuming the increased food resource.Thus, DOC levels decline downstream (oxygen sag) from a pollution source as decomposers metabolize organic waste materials.
7 Plant Nutrients and Cultural Eutrophication Oligotrophic - Bodies of water that have clear water and low biological productivity.Eutrophic - Bodies of water that are rich in organisms and organic material.Eutrophication - Process of increasing nutrient levels and biological productivity.Cultural Eutrophication - Increase in biological productivity (plants & algae) and ecosystem succession caused by human activities (excess fertilizer).An excess of nutrients in water causes accelerated plant growth. Though this is a natural process, it is accelerated when nutrients higher than natural levels enter the water body. Typically, this stimulates the growth of algae and aquatic plants, alters the composition of other species, and makes the water body unsuitable for recreation and other uses. Lake Sammamish, for instance, has had increasing levels of phosphorous enter the lake since the 1960's. Nearly every year now, there are major algal blooms on Lake Sammamish. Such algal blooms are not documented in the history of Lake Sammamish prior to the increase in phosphate levels from urban sources.
8 Inorganic Pollutants Metals Many metals such as mercury, lead, cadmium, and nickel are highly toxic.Highly persistent and tend to bioaccumulate in food chains.Lead pipes are a serious source of drinking water pollution.Mine drainage and leaching are serious sources of environmental contamination.Nonmetallic SaltsMany salts that are non-toxic at low concentrations can be mobilized by irrigation and concentrated by evaporation, reaching levels toxic to plants and animals (selenium & arsenic).Leaching of road salts has had detrimental effect on many ecosystems.Acids and BasesOften released as by-products of industrial processes.Human activities (in particular, mining)speed up the movement of toxic inorganic chemicals from rocks and dirt to water. Heavy metals are the biggest concern including elements such as mercury, lead, cadmium and nickel all of which can be highly toxic in minute quantities.Soils of arid climates often have high concentrations of soluble salts including toxic selenium and arsenic. Irrigation drainage of arid soils can mobilize these substances. Non-toxic such as sodium chloride (table salt) can also be mobilized by irrigation and can reach surface levels that are toxic to animals and plants.Acids are released as by-products of industry and especially coal mining. Sulfur compounds in coal react with oxygen and water to make sulfuric acid. Acid rain is increasing in the amount of surface-water systems it effects. Acids leach aluminum and other elements from rocks and soil resulting in damage to living organisms.
9 Organic ChemicalsThousands of natural and synthetic organic chemicals are used to make pesticides, plastics, pharmaceuticals, pigments, etc.Two most important sources of toxic organic chemicals in water are:Improper disposal of industrial and household wastesRunoff of pesticides from high-use areasFields, roadsides, golf coursesSome dissolve out of the products we usePerhaps the most famous of organic chemicals is DDT and we earlier covered its implications on birds with respect to lower viable reproductive rates. Chlorinated hydrocarbons accumulate in the fat of fish, in fish-eating birds and in humans causing health problems.
10 SedimentHuman activities have accelerated erosion rates in many areas.Cropland erosion contributes about 25 billion metric tons of suspended solids to world surfaces each year.Sediment can either be beneficial (nourish floodplains) or harmful (smother aquatic life).Sediment fills lakes, obstructs shipping channels, clogs hydroelectric turbines and makes water purification harder. Sediment is the largest source of water pollution in the U.S. Sediments smother gravel beds where insects seek shelter and fish lay eggs.
11 Sediment & industrial waste flowing into Lake Erie
12 Thermal PollutionRaising or lowering water temperatures from normal levels can adversely affect water quality and aquatic life.Oxygen solubility in water decreases as temperatures increase.Species requiring high oxygen levels are adversely affected by warming water.Higher temperatures affect coral growthIndustrial cooling systems often use heat-exchangers to extract excess heat, discharging heated water back into original source.Thermal PlumeProduce artificial environments which attract many forms of wildlife.May also adversely affect local lifeEffluent from cooling plants (especially power plants) changes water temperature, and this change has a negative impact on aquatic life. Water temperatures are generally more stable than air, and so abrupt changes in water temperatures disrupts biological systems where aquatic organisms are not adapted to such temperature ranges. Altering vegetation and runoff patterns can also cause thermal pollution.Warm water plumes from power plants attract fish and birds in cold weather. This can be fatal, however, as shown with the endangered Florida manatee. The manatees use the thermal plumes as winter refuge, but if the power plants shut down, the manatees die from themal shocks
13 Part 7: Water Quality Today This figure shows the percent of water quality impaired U.S. rivers in 1998 (U.S. EPA). It's important to notice that in some cases the percentages seem more a function of political boundaries then they are likely of reality, as this information is reported by states voluntarily. According to this data, Washington State is among the least polluted states in the United States. The State of Mississippi is by far the most polluted. It is a known fact that Washington State has suppressed the release of information on mercury contamination in the upper reaches of the Columbia River. Also, there are different standards by which states determine whether water is impaired in quality; however, it's obvious from this figure that water quality impairment is a serious issue in U.S. rivers.
14 Groundwater and Drinking water Pollution About half the US population, and 95% of rural residents, depend on underground aquifers for drinking water.For decades, groundwater was assumed impervious to pollution.Soils/rocks above aquifers would somehow take care of any pollutants (years ago, just wastes)The Earth’s a big place, right?The EPA estimates that 4.5 trillion liters of contaminated water seep into the ground in the U.S. every day. A gasoline additive (MTBE), a suspected carcinogen, is present in many urban aquifers. In agricultural areas, fertilizers and pesticides commonly contaminate aquifers and wells.
16 Underground storage tanks – an example That’s where the gasoline is stored at your local gas stationOver time, they (and the pipes going to the pumps) leakThe gasoline seeps downward into shallow aquifersBenzene, toluene, xylenes, methyl tertiary butyl ether (MTBE)Benzene & MTBE known carcinogensBenzene can degrade somewhat quickly; MTBE is more stubborn
17 Progress and Problems in Other Countries Sewage treatment in wealthier countries of Europe generally equal or surpass the US.In Russia, only about half of the tap water supply is safe to drink.In urban areas of South America, Africa, and Asia, 95% of all sewage is discharged untreated into rivers.Two-thirds of India's surface waters are contaminated sufficiently to be considered dangerous to human health.The situation in most of the undeveloped world is very different than in the U.S., Canada, and most of the developed world. This slide shows a slum in Haiti. It not only looks bad, but it is deadly in many different ways. The water in the ditches is likely filled with toxic and infectious materials. Health risks to humans under these conditions are very high. In particular, infant mortality is almost always extremely high under these conditions.Is easy to talk about people in these situations as being uneducated and backward. It is very difficult, however, for people dealing with acquiring the very necessities of life to think about the impacts of water quality on others. In the U.S., we take clean water for granted, as we have any number of professionals protecting the quality of our water. There are no such professionals protecting surface water quality in this scene in Haiti.
18 Part 8: Pollution Control Nonpoint Pollution Sources and Land ManagementReduce nutrient loading thru land use regulationsSource reduction is cheapest and most effective way to reduce pollution. To work society must get public and business leaders to avoid producing or releasing substances into the environment.Studies show as much as 90% less road salt can be used without significantly affecting winter road safety.Soil ConservationBanning phosphate detergentsSewage TreatmentRemediationThe most effective and most cost-effective way of pollution control is to avoid having the pollution produced and released in the first place. This is called source reduction. Once the pollutants have been released into the environment, it normally takes much more money to clean that pollution from the environment. The benefit of such an unnecessary clean up to the environment is lower. In particular, where potential pollutants can be collected and recycled or reused, money can actually be made in the process of preventing pollution.For instance, it is a nearly universal practice in the photography business to include silver traps that removed the saw silver from waste water produce during photographic development. Prior to the development and use of these traps, millions of dollars worth of dissolved silver contaminated water supplies. Soluble silver is highly toxic.The banning of DDT as an insecticide in the U.S. has reversed the negative impacts this pesticide caused on the top food chain predators. Alternative pesticides were developed that did not show these negative impacts, but still control the same insect pests. These might not have been developed as quickly if DDT was not banned. Major efforts toward pollution control presently include efforts to limit nonpoint source pollution through land management practices. Other current approaches to remove pollution include adding more sewage treatment facilities to smaller municipalities and remediation of polluted sites.
19 Sewage Treatment Rationale More than 500 pathogenic bacteria, viruses, and parasites can travel from human or animal excrement through water.Natural ProcessesIn many areas, outdoor urination and defecation is the norm (do bears do something in the woods?).When population densities are low, natural processes can quickly eliminate waste.Artificial Wetlands Are a Low Cost MethodNatural water purificationEffluent can be used to irrigate crops or raise fish for human consumption.The rationale for continuing to improve on sewage treatment procedures and number of facilities is unquestionable. If for no other reason, the large improvement in water quality has resulted in a massive drop in mortality rates in developed countries during the 20th century. Many less developed areas, however, cannot afford or operate high technological water purifying facilities. In such areas, natural systems might be used to clean water. In fact, at low population densities, natural processes quickly eliminate wastes.As water infiltrates soil and moves through wetlands, it is also purified. Recently, artificial wetlands have been developed as an inexpensive means of purifying water. Similarly, forest soils clean water of organic compounds and pathogens. Wetlands, in particular, have become a partial solution to cleaning water for areas where there is currently not enough money or know-how to develop sewage treatment facilities.
20 Municipal Sewage Treatment Primary Treatment - Physical separation of large solids from the waste stream.Secondary Treatment - Biological degradation of dissolved organic compounds.Effluent from primary treatment transferred into trickling bed, or aeration tankEffluent from secondary treatment is usually disinfected (chlorinated) before release into nearby waterway.Tertiary Treatment - Removal of plant nutrients (nitrates and phosphates) from secondary effluent.Chemicals, or natural/constructed wetlands.In many US cities, sanitary sewers are connected to storm sewers (ummmmm… maybe, Atlanta???).Heavy storms can overload the system, causing by-pass dumping of raw sewage and toxic runoff directly into watercourses.To really get sewage water drinkable, fishable and suitable for natural systems, a 3 step treatment process is required (primary, secondary and tertiary). A problem in many cities, including Seattle, is that sewer pipes are often incorporated into drains for precipitation runoff. When floods occur, these systems overflow and the sewage is often dumped untreated into lakes, rivers and streams.
21 Sewage TreatmentThis figure shows the processes of a typical secondary treatment sewage plant such as those at the Renton and West Point plants in Seattle. The first step of treatment is water collection into the treatment plant. As mentioned on the last slide, if systems are not well maintained or with natural disasters overflows occur and raw sewage can be lost from the collection system.Primary treatment of wastewater includes removing suspended solids in the wastewater by sedimentation and screening. You can imagine what the screened and sedimented material looks like. It is called primary sewage sludge. In Seattle, the primary sludge is further processed by a process called anaerobic digestion, which reduces its potential BOD and stabilizes it.Secondary treatment includes several potential processes, but typically nutrients and air are added to the waste water to stimulate microbial growth. In the process of growing, microbes absorb dissolved nutrients from the water and many other substances stick to the microbial bodies. These microbial cells are then sedimented from the wastewater and further processed, often by mixing with the primary sewage sludge.In Seattle's case, chlorine is then added to the water to disinfect it and most of it is discharged into Puget Sound. Some is recycled as cooling water by Boeing, in some misapplied to golf courses, conserving potable water. The environmental impacts of discharge are unknown but likely very small. If the nutrient load that is removed as sewage sludge were discharged the effect would be substantial due to the fertilization of the water.Typical organic compounds in released wastewater. Concentrations in micrograms per liter. (numbers as of 2002)
22 Water RemediationContainment methods confine liquid wastes in place, or cap surface with impermeable layer to divert water away from the site.Extraction techniques are used to pump out polluted water for treatment.Oxidation, reduction, neutralization, or precipitation.Living organisms can also be used effectively to break down polluted waters.There are many ways to clean water. Containment methods keep dirty water from spreading. Chemicals may be added to toxic water to precipitate, immobilize or solidify contaminants. Pollutants may be outright destroyed of detoxified by chemical reactions that oxidize, reduce, neutralize, hydrolyze, precipitate the pollutant chemical composition.Bioremediation is the process of using living organisms to clean contaminated water. This method can be effective and cheap. Wetlands are a general type of bioremediation. A small flowering plant called duckweed (lemna spp.) is used to remove organic nutrients from water. The duckweed can also be harvested and used as feed, fuel or fertilizer.
23 Part 9: WATER LEGISLATION Clean Water Act (1972)Established uniform, nationwide controlsGoal was to return all U.S. surface waters to "fishable and swimmable" conditions.For point sources, discharge permits and “best practicable control technologies” are required.Set zero discharge requirement for 126 priority toxic pollutants.Amended in 19851972 was a benchmark year for the improvement of water quality. It was this year that the first Clean Water Act was passed. This initial act has been followed by an increasing awareness by U.S. politicians that sometimes effective legislation is the best and fastest way to solve water pollution and that most Americans want clean water. There is disagreement on what the priorities are and just exactly how we go about getting things right. Chapter 15 will deal with legislation progress and evolution in more detail.
24 Other important legislation Safe Drinking Water Act (1974)Minimum safety standards for all community water suppliesResource Conservation & Recovery Act (RCRA) (1976)Regulates storage, shipping, processing & disposal of hazardous wastesToxic Substances Control Act (TOSCA) (1976)Categorizes toxic & hazardous substancesRegulates use & disposal of poisonous chemicals
25 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA; “Superfund”) (1980) and Superfund Amendments & Reauthorization Act (SARA) (1984)Sealing, excavation, or remediation of toxic & hazardous waste dumpsFunded mainly by a tax on petroleum & chemical companies in the past (you know who payed that?......)
26 Emergency Planning & Community Right-to-Know Act (1986) Part of SARA Not really water-relatedHas to do with chemicals present in the workplaceFor any chemicals used by a company, a Material Safety Data Sheet (MSDS)must be readily availableGives the product’s makeup, it’s properties, hazards, and lots of other fun stuffTechnically, an MSDS is also needed for water in the water cooler