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1、Main problem,What is EL NINO? What disaster does the EL NINO produce? How does the EL NINO form? What should do human beings to face EL NINO?,Section 5 Environmental Action of EL NINO,Video 6 The Fury of EL NINO 004646,CHAPTER 3 WATER RESOURCES,We live, quiet literally, in a watery world. All living
2、 things depend absolutely on a supply of water. The biochemical reactions of every living cell take place in aqueous solution, and water is the transport medium for the nutrients and waste products it excretes. Water is abundant on the planets surface, but about 97 percent of Earths supply of water
3、is in the oceans, where it is too salty to be used by humans or other land creatures.,SECTION 1 GLOBAL PERSPECTIVE,Every day, however the suns rays distill a large quantity of water that falls back to the surface as rain. Proportionately more rain falls on land than on the oceans, providing a contin
4、ual supply of freshwater. We treat water as if it was free, and, In a sense, it is freea by-product of the enormous flux of solar energy on Earth. The hydrologic cycle accounts for about half of solar energy absorbed by Earths surface.,The global movement and storage of water is illustrated in Figur
5、e 10.1. Every year, 111,000km3 water falls on land, and 70, 000km3 returns to the atmosphere via evaporation from wet surfaces and transpiration from plants; there two processes are called collectively evapotranspiration. The remainder, 41,000km3, is the runoff, which eventually reaches the oceans.,
6、If the runoff divided evenly, it could provide each person with 6,760m3 a year of freshwater. But of course it is not divided evenly. Some continents are rainier than others, and the variation within continents is even greater (see Table 10.1).The runoff per km2 of land area in South America, for ex
7、ample, is over four times as much as in Africa, while within Africa, the runoff per km2 in the Congo is 12 times as much as in Kenya.,TABLE 10.1 ANNUAL WATER SUPPLY AND WITHDRAWAL FOR CONTINENTS AND VARIOUS COUNTRIES,SECTION 2 U.S.WATER RESOURCES,To gain a more detailed perspective on water resource
8、s, we examine the pattern of distribution and use in the continental United States. A schematic of the water flows is given in Figure 10.4. As in the global water cycle, about two-thirds of the precipitation is returned to the atmosphere via evapo- transpiration(蒸发蒸腾); the balance goes to runoff, am
9、ounting to about 2,000km3/yr. Most of the water is in the east of the country, and flows to the Atlantic and Gulf coast. A quarter of annual runoff(468 km3) is withdrawn for various uses, of which three-quarters(338km3) is subsequently returned to the streamflow and the remainder is “consumed,” most
10、ly through evapotranspiration after or during use; eventually, of course, all the water is returned to the global cycle.,The pattern of water utilization is graphed in Figure 10.5. Of the 470 km3 of freshwater used in 1995, 77percent was from surface supplies and the rest was from groundwater, which
11、 is eventually recharged from the surface. Water usage is dominated by agriculture and by the cooling of electric generators, each of which requires about 40 percent of the supply. The remaining 20 percent is divided between industry and mining on the one hand (8percent), and domestic and commercial
12、 uses on the other(12 percent).,Major industrial users are the steel, chemical, and petroleum industries; the mining uses include water extraction of minerals and fossil fuels, and milling and related activities. Most of the industrial and mining water is obtained directly from surface and groundwat
13、er, but about 20 percent of it comes from public supplies, which also provide most of the domestic and commercial water. Domestic uses (drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and watering lawns and gardens) amounted to about 380 liters(100gallons)per day p
14、er person. The total was about three times higher than for commercial uses (hotels, restaurants, office buildings, and so on ),While agriculture is a heavy user of water throughout the country, irrigation is especially important in the arid west, where extensive diversion of the major waterways has
15、permitted large scale crop production. California and Idaho are the largest users of irrigation water, together accounting for 34 percent of the national total.,The influx of citydwellers also strains the water resources of arid regions. The south-western metropolises of Los Angeles, San Diego Las V
16、egas, Tucson, and phoenix all experience serious water management problems and conflicts over access to distant supplies of water.,The total water capacity in the earth is about 1.3861018 m3，but only fresh water of 0.3 is available. In China, surface water is about 2.81012m3，ground water is about 81
17、011m3, glacier is about 51010m3. the total available water resource is about 1.11012m3, average quantity per person is only 2700m3.,SECTION 2 CHINA WATER RESOURCES,SECTION 3 COMPOSITION OF NATURAL WATER,1. Water body definition,Water is different from water body.,2. Composition,Suspended material Co
18、lloid Soluble substances,Sea water,River water,3. Main ion,River water: HCO3- SO42- Cl-， Ca2+ Na+ Mg2+,Sea water: Cl- SO42- HCO3-， Na+ Mg2+ Ca2+,Microelement is at ng/mL level.,4. Microelement,5. Nutrimental material,N, P, Si, Mn, Fe, Cu-mg/mLng/mL,6. Organic material,Humus,7. Dissolved gas,In seawa
19、ter,CHAPTER 4 WATER POLLUTION AND WATER TREATMENT,The quality of surface and groundwater is of concern from two overlapping but distinct points of view: 1) human health and welfare; and 2) the health of aquatic ecosystems. Both aspects of water quality are enhanced by minimizing the impacts of human
20、 activities, but the specific issues and control measures are different.,SECTION 1 WATER USE AND WATER QUALITY: POINT AND NONPOINT SOURCES OF POLLUTION,Water quality is as important an issue as water quantity. Although most of the water supply is returned to the stream flow after use, its quality is
21、 inevitably degraded. The effects are summarized in Table 4.1.,The cooling of power plants by circulating water raises the temperature (thermal pollution), with adverse effects on the biota of the receiving waters. Discharge of sewage from homes and commercial establishments reduces the dissolved ox
22、ygen content, again upsetting the biological balance of surface waters.,1. Point source of pollution,Industrial and mining activities contaminate water with a variety of toxic materials. Agriculture can foul surface and ground waters with excess nutrients, and can lead to salinization of soil when i
23、rrigation waters evaporate, leaving salts behind.,TABLE 4.1 EFFECTS ON WATER QUALITY FROM WATER USE,TABLE 4.2A TOP TEN INDUSTRIES FOR SURFACE WATER DICHARGE(1999),TABLE 4.2B TOP TEN CHEMICALS IN SURFACE WATER DISCHARGE (1999),Figure 4.1 shows the reduction of U.S. discharges from 1988 to 1996 of che
24、micals included in the Toxic Release Inventory (TRI) that is maintained by the EPA. Discharges to surface waters were reduced by nearly a factor of four, while transfers to publicly owned treatment works (POTWs) were nearly halved. The POTW transfers are particularly significant because treatment wo
25、rks are designed to handle domestic sewage, primarily, and have often been disabled by industrial discharges in the past. Figure 4.1 actually understates the improvement in pollutant discharges because the TRI is an aggregate of all toxic chemicals, the most abundant of which are the least toxic (se
26、e Table 4.2b). Releases of the most toxic chemicals have been cut more sharply.,Figures 4.2 and 4.3 show that POTW transfers have been cut by factors of five and nine for benzene and chromium, respectively, two chemicals that are known to cause cancer. (The discharges to surface waters have been cut
27、 less, because they were relatively small to begin with.),Nonpoint sources represent a much harder problem. They include emissions from transport vehicles, agricultural runoff, which can carry excess nutrients, pesticides, and silt(淤泥) into streams and ground waters, and urban runoff, which can carr
28、y toxic metals and organics through storm drains into sewage treatment plants, or directly into rivers and lakes (see Figure 14.4). The progress made in controlling point sources of pollution has drawn attention to nonpoint sources, which account for an increasing fraction of the total pollutant loa
29、d. For example, the relative contribution to the cadmium (Cd) load to the Rhine River from point and nonpoint sources changed dramatically between the mid 1970s and mid 1980s (see Figure 4.5).,2. Nonpoint source of pollution,While most of the Cd came from point sources in the 1970s, this is no longe
30、r the case, thanks to industrial controls. Now the greater share of Cd derives from nonpoint sources from urban and agricultural runoff (Cd is a contaminant in urban dust as well as in phosphate fertilizer). As discussed above, nonpoint sources are responsible for the overfertilization of lakes and
31、bays.,Section 2 Water Body Pollution,1. Water body pollution and its self-purification,Definition,Physical self-purification Chemical self-purification Biological self-purification,2. Pollutants in water body,(1) Pathogenic pollutant,For instance, Virus, germina, parasite,Schistosomiasis, cholera, d
32、ysentery, hepatitis,In 1848 and 1854, ten thousands people died of cholera because of water pollution in England. In 1892, 750 people died of cholera in Germen.,Characteristic of pathogenic pollutant： Big quantity wide distributing long life fast reproduction drug-fast good life-force,(2) Oxygen con
33、sumed pollutant,Carbohydrate, protein, grease, xylogen,Sulfureted hydrogen, ammonia,(3) Plant nutriment,Nitrogen and phosphorus is from sewage, fertilizer, waste, trash.,Definition of eutrophication,(4) Venomous pollution,Heavy metal: mercury, cadmium, chromium,Inorganic ion: NO2-、F-、CN-,Definition,
34、Sort,Organic pesticide, PCB,Carcinogen: PAHs, heterocyclic compound, aromous amine,Common organic compound,(5) crude oil pollutant,(6) Radioactive pollutant,(7) Acid, base and salt inorganic pollutant,(8) Heat pollution,40K、238U、286Ra、210Po、14C、3H,SECTION 3 QUALITY EVALUATION OF WATER BODY,Pollution
35、 index for organic substances,1. DO (dissolved oxygen),Natural water body, DO is about 814 mg/L,Analytical method for DO in water. Chemical method and instrumental method.,When DO4 mg/L，fish die.,2. BOD (biochemical oxygen demand),mg(O2)/L,First phase, organic substances are changed into CO2, H2O an
36、d NH4+,Second phase, NH4+ are changed into NO2-, NO3-,20，5 d, BOD5,3. COD (chemical oxygen demand),Method of KMnO4 Method of K2Cr2O7,In general, K2Cr2O7 CODBOD5 KMnO4 COD,mg(O2)/L,4. TOC (total organic carbon ) and TOD (total oxygen demand ),Chemical combustion method,Weak relativity among TOC, TOD
37、and BOD5,Quality criterion for surface water（mg/L）,SECTION 4 REGULATION OF WATER QUALITY,Governments around the world try to regulate water quality in the interests of public health and Environmental protection. In the U.S. , the legal instruments for regulation are two basic laws, the Clean Water A
38、ct (CWA) of 1972 and the Safe Drinking Water Act (SDWA) of 1974 , both of which have been amended several times. Under these acts, the EPA is required to set standards that protect from harmful effects of contaminants-discharges of point-source pollutants are subject to a permitting process, industr
39、ies are advised with respect to the best available pollution control technologies, and resources are provided for the construction of municipal treatment plants.,Similar initiatives have been undertaken in most other industrialized countries. These measures have helped to produce marked reduction in
40、 pollutant discharges to water bodies , as noted in the preceding section.,Under the SDWA, standards have been set for mircroorganisms, radionuclides, and 54 organic and 14 inorganic chemicals, which can sometimes be found in drinking water. The standards are set as maximum contaminant levels (MCL),
41、 which are as close as is technologically feasible to the maximum contaminant level goal (MCLG). The MCLG is the level of a contaminant in drinking water below which there is no known or expected risks to health. Although sensible-sounding, the MCLG is a difficult quantity to establish. As more data
42、 on health effects accumulate, and more sensitive measures are used, the MCLGs tend to be readjusted downward. In many cases there may be no threshold below which some health effect could be expected. Indeed, several MCLGs have been set at zero (e.g., benzene, dichloromethane, carbon tetrachloride,
43、dioxin, PCBS, lead), although zero is an unattainable goal.,The legally enforceable MCLGs are set by considering the best available technology that is economically feasible. The MCLGs range from a high of 10 mg/L (nitrate ion) to a low of 0.0002mg/L heptachlor epoxide(七氯环氧化合物) and lindane（林丹）. For m
44、icroorganisms, the rule is that filtration and disinfection must remove or inactivate 99.9 percent of Giardia(贾第鞭毛病虫) and 99.99 percent of viruses, and no more than 5 percent of samples in any month can test positively for coliform(大肠菌) bacteria. In the case of copper and lead, the source of drinkin
45、g water contamination is generally the plumbing(管道) system, and water utilities are required to take treatment steps if 10 percent of tap water samples exceed 1.3mg/L of lead.,For surface waters generally, the quality issue comes down(涉及到) to the ability to support aquatic ecosystems, and human uses
46、 such as swimming and fishing. The Clean Water Act of 1972 established a mechanism for protecting these waters by requiring states to set a total maximum daily load (TMDL) of pollutants at a level that ensures water quality standards in a given waterway. If the TMDL is exceeded, required pollution r
47、eduction are to be allocated among the pollution sources.,This provision of the CWA was not enforced for many years, until lawsuits brought by environmental groups in more than 30 states led the EPA to propose an implementation rule in 1999. The need for action was justified by the results of a 1998
48、 survey that indicated that some 40 percent of assessed streams, lakes, and estuaries(河口) in the U.S. were not clean enough to support uses such as swimming or fishing. The EPAs rule specifies procedures for states to follow in identifying impaired waterways, establishing a budget of pollution reduc
49、tion, and producing an implementation plan.,Although the rule is intended to implement a 30-year-old law, and gives states up to 15 more years to do so, it has run into strong opposition because of the difficulty of controlling nonpoint sources of pollution, which have become the new battleground of environmental protection. Some of the provisions of the EPAs rule are intended to bring pollution generated by forestry and agriculture under the CWA regulations, although these sectors have previously been exempted（免除）. Much of the opposition cente