Bài giảng slide water pollution

Chapter 15 Water Pollution Water Pollution While it is true that substantial quantities of fresh surface and ground water are unpolluted by human activities, much of this water is far removed from population centers Mean while, the quality of most of the accessible water has been degraded Geochemical Cycles Many naturally occurring elements, minerals and chemicals are naturally cycled through the environment (it is similar to the hydrologic cycle) The elements pass thru a series of “reservoirs” Residence Time How much time each element spends in a liquid reservoir, such as a river stream, lake or ocean, is called the residence time Residence Time The capacity, for a naturally occurring, dissolved substance, is the concentration that can be reached before the reservoir becomes saturated and the substance precipitates Residence Time Residence times will differ for any given element in different reservoirs with different capacities The rate of influx of additional material is also important Residence time is an average For example, if a specific chemical has a residence time of 20 years, then after 20 years about half of the chemical should be gone from the reservoir Residence Time Note that the residence time for sodium and chlorine in the oceans is a very long time In contrast, iron can precipitate out of seawater very easily and the residence time is only 200 years Pollution & Residence Time We can also apply the concept of residence times to toxic chemicals that are introduced into nature as human-created pollution Unfortunately, there is very little scientific information about the behavior of many toxic chemicals and pollutants in the environment Pollution & Residence Time Also, it makes a tremendous difference whether the pollution is a one-time event or continues over time In the worst case scenario, pollution can overwhelm a reservoir Pollution Sources Pollution sources may be divided into Point sources Nonpoint sources Leadville, Colorado Investigators picked one pile of mining wastes and made an airborne spectral traverse and then took ground samples to compare Leadville, Colorado Comparing the air borne spectral data to the analysis of the ground samples, they were able to identify zones of different mineralogy Leadville, Colorado These zones of mineralogy were found to correspond with varying degrees of acidity from the mine drainage (This is an example of ground truthing remote sensing data) Leadville, Colorado Next they applied the info gained from the ground sampling of this one area to all of the mine wastes in the entire area around Leadville, creating a regional map of toxic metal pollution to be used to plan a Superfund clean up Leadville, Colorado Opps!! The White House and Congress has killed the superfund Therefore, Leadville is not being cleaned up Rocky Mountain Arsenal The Rocky Mountain Arsenal was a U.S military chemical weapons manufacturing center located in the in Commerce City, Colorado near Denver The manufacture of these weapons continued from WWII until 1969 Through the 1970s until 1985, RMA was used as a demilitarization site to destroy munitions and chemically related items Rocky Mountain Arsenal Coinciding with these activities, from 1946 to 1982, the Army leased RMA facilities to private industries for the production of pesticides One of the major lessees, Shell Oil Company, along with Julius Hyman and Company and Colorado Fuel and Iron, had manufacturing and processing capabilities on RMA between 1952 and 1982 Rocky Mountain Arsenal The first reports of water contamination were reported in the early 1950s and RMA began to use asphalt lined containment ponds By the early 1970s, there were renewed reports of crop and animal damage The state of Colorado investigated and the true extent of the pollution was finally realized Rocky Mountain Arsenal The primary contaminants include chlorinated pesticides, organophosphate pesticides, insecticides, organic solvents and chemicals used as raw products or intermediates in the manufacturing process, heavy metals, and chemical warfare materiel and their related breakdown products The groundwater contamination was so extensive, the only feasible approach was to contain the further spread was to halt the pollutants at the RMA boundary Rocky Mountain Arsenal A physical barrier of clay-rich material was placed along the arsenal side of the boundary at several locations, where the natural groundwater flow was outward from the arsenal Rocky Mountain Arsenal On the arsenal side, wells extract the contaminated water and it is treated by a variety of processes, including filtration, chemical oxidation, air stripping and activated charcoal The clean water is released outside of the arsenal boundary Rocky Mountain Arsenal About $25 million has been spent cleaning up RMA and today, it is a national wildlife refuge Rocky Mountain Arsenal They even allow fishing “The Rocky Mountain Arsenal National Wildlife Refuge Sport Fishing Program has provided recreational opportunities to many people in Denver and the surrounding communities since 1990 Statistics show a catch rate of greater than one fish per hour during the past ten years.” Rocky Mountain Arsenal Would you eat the fish? Chapter 16/17 Air Pollution [...]... source of pollution in water Almost all treated and untreated human sewage is dumped into bodies of water The Psyttalia Wastewater Treatment Plant in Greece is Europe’s largest sewage treatment facility Organic Matter Feedlots and other animal-husbandry activities create large concentrations of animal wastes Food-processing plants are another major source of organic matter discharged into water Typical... nutrients into the water Oxygen Concentrations Dissolved oxygen concentration in the U.S Oxygen dissolves more readily in cold water than in warm, accounting for some regional differences Phosphates Phosphates in sewage and waste water behave as plant nutrients and are harmful to the environment Phosphates were added to laundry detergents to enhance their cleaning ability by softening the water, but their... wastes to local groundwater and streams Organic Matter Human and animal wastes are major vectors for spreading disease Sewage can cause the outspread of infectious diseases such as cholera, typhoid, yellow fever, malaria and various other mosquito diseases Organic Matter In nature, over time, organic matter in water is broken down by microorganisms If there is ample oxygen in the water, aerobic decomposition... than running water Eutrophication The breakdown of excess organic matter not only consumes oxygen, but it also releases a variety of compounds into the water, such as nitrates, phosphates and sulfates The nitrates and phosphates are plant nutrients that encourages the rapid and excessive growth of aquatic plants, especially algae When this occurs, it is described as the eutrophication of the water (or... When this occurs, it is described as the eutrophication of the water (or the body of water is described as eutrophic) Sources of Eutrophication Algal Bloom The exuberant algal growth is called algal bloom and appears as slimy green scum floating on the water Once this condition starts, it acts to rapidly worsen the water quality The scum blocks out the sunlight and the aquatic plants begin to die Algal.. .Pollution Sources Point sources are sources from which pollutants are released from one readily identifiable spot Examples include a sewer outlet, steel mill or septic tank Pollution Sources Nonpoint sources are more diffuse Examples include fertilizer runoff from a farm or acid drain from a strip mine BOD The organic load in a body of water is described by a parameter... their cleaning ability by softening the water, but their use in now restricted Industrial Pollution The National Research Council compiled a list of 66,000 drugs, pesticides and chemical used in industry No toxicity data at all were available for 70% of them Only 2% had complete health hazard evaluations Industrial Pollution Toxic metals are industrial pollutants of special concern Manufacturing and mining... by microorganisms in both fresh and salt water These methylmercury compounds are taken up by aquatic plants and small organisms at the bottom of the food chain Eventually, the methymercury accumulates in fish, which are at the top of the food chain in aquatic environments The problem is that people eat fish Mercury Testing of mercury level in fresh and salt water fish in the 1960s and 1970s produced... demand (BOD) The BOD of a system is the amount of oxygen needed to break down the organic matter aerobically Specifically, BOD measures the rate of uptake of oxygen by microorganisms in the sample of water at a fixed temperature (20°C) and over 5 days in the dark BOD Most pristine rivers will have a 5 day BOD of less than 1 ppm Heavily polluted rivers will have a 5 day BOD greater than 10 ppm Oxygen... Testing of mercury level in fresh and salt water fish in the 1960s and 1970s produced alarming results People were advised to limit their intake of fish, especially tuna It took many years of enhanced pollution controls to reduce the mercury levels Mercury The occurrence of methylmercury in ppb Minamata, Japan “Minamata is a small Japanese fishing town living in the shadow of the chemical factory of