Chapter 9
how much of the population lacks safe drinking water? What percent of developing countries don't treat sewage water?
20%, 90%
Facts:
200 million people live in water stressed areas. Estimates suggest that by the year 2025 approximately 2.8 billion people will live in 48 countries that will experience water stress or water scarcity. These numbers will increase by the year 2050 to 54 countries with a combined population of 4 billion people.
how much freshwater is there on Earth? How much of that can we (as humans) use?
3%, 0.01%
Of the freshwater...
75% is found in frozen polar ice caps and glaciers, 1% of readily available freshwater comes from surface water - this is restored by the hydrological system.
water stress
A country faces water stress when its annual supply of renewable freshwater is between 1,000 and 1,700 cubic meters per person.
Aquifer
A layer or section of earth or rock that contains freshwater, known as groundwater (any water that is stored naturally underground or that flows through rock or soil, supplying springs and wells).
How long can a human survive without food or water?
Although it is possible for a human being to live up to a month without food, that same individual can survive for only about a week without water.
Process of treatment
Aluminum sulfate is a coagulation agent, then filtered by sand and activated charcoal, treated with a disinfectant such as chlorine to destroy pathogens.
Transmission
Contaminated surface water sources and large, poorly functioning municipal water distribution systems contribute to transmission of waterborne bacterial diseases. Chlorination and safe water handling can eliminate the risk of waterborne bacterial diseases.
Trends
Despite global efforts, improvements in water and sanitation infrastructure have barely kept pace with population increases and migrations in the developing world.
Incidence of Waterborne Diseases
Each year, an estimated 4 billion episodes of diarrhea result in an estimated 2 million deaths, mostly among children. Waterborne bacterial infections may account for as many as half of these episodes and deaths.
Enteric protozoal parasites
Entamoeba histolytica • Giardia intestinalis • Cryptosporidium parvum • Cyclospora cayetanensis
Example of diseases
Examples of waterborne diseases are cryptosporidiosis and giardiasis (both caused by protozoan agents), cholera (agent Vibrio cholerae), and infection with E. coli O157:H7.
Petroleum Spills
Exxon Valdez - one of the worst in US history - spilled 10.9 million gallons, impacted over 1,100 miles of non-continuous coastline in Alaska, 350,000-390,000 birds killed, 3500-5500 Sea Otters (60% fatality rate), 200 harbors seals January 28, 1969 - extensive oil spill off the coast of Santa Barbara, operated by Union Oil Company, 11 days and 3 million gallons of oil escaped, 3,600 birds were killed - killed many more things as well Deepwater Horizon, April 20-July 15, 2010- largest accidental marine oil spill in HISTORY 60,000 barrels perday - 5 millions barrels of oil into the Gulf of Mexico
Sequelae
Many deaths among infants and young children are due to dehydration, malnutrition, or other complications of waterborne bacterial infections.
Freshwater Lakes
Most freshwater lakes are located at high latitudes, with nearly 50% of the world's lakes in Canada alone. Many lakes, especially those in arid regions, become salty through evaporation, which concentrates the in flowing salts. The Caspian Sea, the Dead Sea, and the Great Salt Lake are among the world's major salt lakes.
Risk Groups
Over 2 billion persons living in poverty in the developing world are at high risk. Certain US groups (residents of periurban "colonias" and remote rural areas with poor water treatment and delivery systems) are also at risk.
Filtered Water
The drinking water delivered to distribution system after treatment
How much do we use in US?
United States the average person uses about 100 gallons (about 400 liters) of water per day, and the average residence uses over 100,000 gallons (about 400,000 liters) during a typical year, 50-70% is used for outdoor purposes, 5% loss to system leaks
Source Water, surface water
Untreated water used to produce drinking water, all water on the surface
Runoff (2)
Urban runoffresults in loss of wetlands, which act as natural water filtering mechanisms - excessive amounts of nutrients that enter the oceans may cause harmful blooms of algae which reduce oxygen exposes swimmers to waterborne disease storm water runoff is a leading cause of ocean pollution
Runoff
Water originating as precipitation on land that then runs off the land into rivers, streams, and lakes, eventually reaching the oceans, inland seas, or aquifers, unless it evaporates first.
wetlands
Wetlands include swamps, bogs, marshes, mires, lagoons and floodplains. Earth's 10 largest wetlands are: West Siberian Lowlands, Amazon River, Hudson Bay Lowlands [in Canada], Pantanal [in mid-South America], Upper Nile River, Chari-Logone River [in Africa], Hudson Bay Lowlands in the South Pacific, Congo River, Upper Mackenzie River [in northwestern Canada], and North America prairie potholes
water scarcity
a country faces water scarcity when its annual supply of renewable freshwater is less than 1,000 cubic meters per person.
Guinea Worm Disease
also called dracunculiasis, little larvae grow to be big and when human host goes in water, the baby larvae are release to continue living happy larvae lives
reserviors
artificial lakes, constructed by physical barriers across flowing rivers allowing water to pool
How much water does one need?
average requirement for human consumption of water per day is approximately 2.5 liters
Viral Hep A and Hep E
can be spread via fecal-oral route by contaminated food and water, linked to clams and mollusks
Legionnaires' Disease
case-fatality rate = 15%, fever, cough, chest pain, pneumonia, freshwater lakes, stream and rivers
Water Disinfection Byproducts (DBPs)
chemicals associated with byproducts of chlorination called DBPs are Chlorine, Chloramines, chlorine dioxide, and ozone, Trihalomethanes (THMs) are most common and widely measured DBPs = cancer and bad reproductive outcomes There are two studies researching reproductive outcomes and chlorine in water little is known about the potential adverse health effect
4 Stages of Water Treatment (in most plants)
coagulation, sedimentation, filtration, and disinfection.
Waterborne Diseases
conditions that are "transmitted through the ingestion of contaminated water and water acts as the passive carrier of the infectious agent."
Glaciers and icecaps
cover about 10% of the world's landmass, These are concentrated in Greenland and Antarctica and contain ~70% of the world's freshwater. 96% of the world's freshwater is at the north and south poles
Fluorosis
describe the dental condition in which teeth have been discolored by fluoride, 50-70 % reduction of dental caries was observed in a clinical trial in grand rapids, MI.
Amebiasis
dysentery, colitis, and appendicitis) and extraintestinal amebiasis (e.g., abscesses of the lungs and liver). avoid fresh fruits and veggies in places where the water sanitation is iffy, because the parasite comes from water that feeds the plants, so grows in plants
Natural Resources Defense Council (NRDC)
estimates half the world's coastal areas are endangered approximately 1 billion people live near coastal areas, population growth rate near coasts is twice the overall global population growth rate.
renewable water
freshwater that is continuously replenished by the hydrological cycle for withdrawal within reasonable time limits
2 main sources for drinking water?
ground water, surface water
Hydrological (water) Cycle
natural water cycle where water evaporates from oceans and other bodies of water, accumulates as water vapor in clouds, returns to oceans and other water bodies as precipitation, 90% of the water returns to the oceans directly
Disease Causing Agents Present in the Water Supply
parasites, viruses, bacteria, chemicals
Study Questions
pg 429
enteric
relating to the intestines
water withdrawel
removal of freshwater for human use from any natural source of reservoir
non renewable water
water in aquifers and other natural reservoirs that is not replenished by the hydrological cycle
Groundwater and groundwater system
water that is contained in the interconnected pores in an aquifer (Water in an underground aquifer), a well or a spring (extracts underground water)
Other Agents
• Dracunculus medinensis • Legionella pneumophila
Viral pathogens
• Enteroviruses • Adenoviruses • Noroviruses (formerly called Norwalk-like viruses)
Bacterial enteropathogens
• Salmonella • Shigella • Escherichia coli • Vibrio cholerae • Campylobacter
