Module 5 Water Resources & Pollution PDF

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This material has been reproduced and communicated to you by or on behalf of University of the Philippines pursuant to PART IV: The Law on Copyright of Republic Act (RA) 8293 of the “Intellectual Property Code of the Philippines”. The University does not authorize you to reproduce or communicate this material. The Material may contain works that are subject to copyright protection under RA 8293. Any reproduction and/or communication of the material by you may be subject to copyright infringement and the copyright owners have the right to take legal action against such infringement. Do not remove this notice. © Institute of Environmental Science & Meteorology, College of Science, University of the Philippines Diliman 1 Fig. 1. The Pantabangan Reservoir in Nueva Ecija. Photo by CLRingor Module 5 University of the Philippines Diliman Water Resources & Pollution Learning Outcomes ! Discuss the water cycle ! Determine the environmental problems associated with water use ! Describe water management & conservation practices 3 The Water Cycle Earth's water is always moving, & the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, & below the surface of the Earth, driven by the sun’s energy & gravity. Water is always changing states between liquid, vapor, & ice, with these processes happening in the blink of an eye & over millions of years. One thing about water does not change. There is only a certain amount of water on Earth— no more, no less—& that total does not change. What changes is how it is distributed in the biosphere, atmosphere, geosphere, & the hydrosphere (reservoirs) & its residence time in each reservoir. Fig. 2. Upstream of Laoag River (left). Photo by CLRingor. 4 Fig. 3. The processes that take place in the cycling of water are the following: rain but also includes snow, sleet, drizzle, & hail. Groundwater: underground water flow Evaporation: process where liquid water changes into water vapor. Condensation: (aquifers). Deposition: process where water vapor (gas) changes into ice (solid), skipping process where water vapor (gas) changes into water droplets (liquid). Plant uptake: the liquid phase. Sublimation: process where ice & snow (solid) change into water vapor water taken from the groundwater flow & soil moisture. Transpiration: evaporation of (gas), skipping the liquid phase. Infiltration: movement of water into the ground from the liquid water from plants & trees into the atmosphere. Transportation: movement of solid, surface. Percolation: movement of water past the soil going deep into the groundwater liquid, & gaseous water through the atmosphere. Runoff: river, lake, & stream transport of (NOAA). Retrieved from https://www.weather.gov/jetstream/hydrocycle_max 15 Sep 2020 water & transport of ice in glaciers. Precipitation: water that falls to the earth, mostly as 5 Distribution of Water on Earth About 71% of the Earth's surface is covered with water, & almost all of it, 97.5%, is saline & found in oceans. Only 2.5% of Earth's water is freshwater - the amount that sustains terrestrial life. Water keeps us alive. We have no substitute for this vital form of natural capital. Unfortunately, we are using available freshwater unsustainably by extracting it faster than nature can replace it, & by wasting, polluting, & underpricing this irreplaceable natural resource. Fig. 4. Surrounding waters of Batan Island (right). Photo by CLRingor. 6 Most of the Earth’s freshwater is not readily available to us. Only a tiny fraction, about 0.0071% of the planet’s water supply, is readily available to us as liquid freshwater (Miller & Spoolman, 2016). They are stored in lakes, rivers, & streams. The rest is in frozen polar ice caps & glaciers & in deep underground deposits or aquifers (Fig. 5). Fortunately, the world’s freshwater supply is continually recycled, purified, & distributed in the Earth’s water cycle, unless we alter it, overload it with pollutants, or extract it faster than natural processes replenish it. On a global basis, we have plenty of freshwater, but it is not distributed Fig. 5. Freshwater sustains terrestrial life. However, only about 0.0071% of the total amount of water on evenly. Earth is freshwater that is readily accessible to us through lakes & rivers. Data from Miller & Spoolman, 2016. Freshwater are also found beneath us. rivers, & streams. However, most lakes, reservoirs, wetlands, streams, When precipitation infiltrates the ground aquifers recharge extremely slowly, & rivers, estuaries, & the oceans. & percolates downward through spaces because so much urban areas have Precipitation that does not infiltrate the in soil, gravel, & rock, the freshwater in been built on or paved over, freshwater ground or return to the atmosphere by these spaces underground is called can no longer penetrate the ground to evaporation is called surface runoff. groundwater. We use pumps to bring recharge aquifers. In addition, in dry The land from which surface runoff this groundwater to the surface for areas of the world, there is little drains into a particular stream, lake, irrigating crops & supplying households precipitation available to recharge wetland, or other body of water is called & industries. Most aquifers are aquifers. Another crucial resource is its watershed, or drainage basin. replenished naturally by precipitation or surface water, the freshwater from rain by lateral recharge from nearby lakes, & melted snow that flows or is stored in 7 Water Consumption Worldwide, we use 70% of the freshwater we withdraw each year from rivers, lakes, & aquifers to irrigate cropland & raise livestock (Fig. 6). In arid regions, on average, 90% of all water withdrawn is used for food production. Industry uses roughly another 20% of the water withdrawn globally each year, & cities & residences use the remaining 10% (UNWWAP, 2017). FAO estimates global freshwater Fig. 6. Consumption & wastewater production by major water use sector (circa 2010). Agriculture uses 70% withdrawals at 3,928 km³ per year. of the freshwater we withdraw each year from rivers, lakes, & aquifers (UNWWAP, 2017). About 44% (1,716 km3 per year) of this water is consumed, mainly by wastewater treatment is generally a Agriculture accounts for 92% of agriculture through evaporation in reflection of its income level: the higher humanity’s water footprint. See the irrigated cropland (cited in UNWWAP, the income, the more wastewater is world map on the next page to see 2017). The remaining 56% (2,212 km3 treated. Another one of life’s ironies, which countries have the largest per year) is released into the poor countries do not have enough footprint (Fig. 7). environment as wastewater in the form resources to treat wastewater, which of municipal & industrial effluent & they so badly need. We use many times more freshwater agricultural drainage water. It is very alarming how much water is wasted. If indirectly. This water is called virtual we can adequately treat wastewater, it Our water footprint is a rough water, the freshwater that is not directly can be a resource that can be used to measure of the volume of freshwater consumed but is used to produce food address water supply shortages. that we use directly & indirectly to stay & other products. It makes up a large However, a country’s level of alive & to support our lifestyles. part of our water footprints, especially in 8  1 pair of shoes (bovine leather) 8000 1 microchip (2 g) 32 The global average water footprint is 1240 m3 cap/yr Fig. 7. Average water footprint per country per person per year in the period 1997-2001 (Hoekstra & Chapagain, 2007). The water footprint of a country is defined as the volume of water needed for the production of the goods & services consumed by the inhabitants of the country. Green means that the nation’s water footprint is equal to or smaller than global average. Countries with red have a water footprint beyond the global average. The Philippines has higher water footprint per person than global average. 3 Fig. 2 Average national water footprint per capita (m /capita/yr). Green means that the nation’s water footprint is equal to or smaller than global average. Countries with redchain, more developed countries. Producing & delivering a typical havethe a water footprint beyond the global average higher will be the virtual water content of the hamburger, for example, takes about 2,400 liters of freshwater product. However, the virtual water content of products — most of which is used to grow grain that is fed to cattle. In strongly varies from place to place, depending upon the The size general, of products livestock the global have a water footprint higher virtual water contentis largelyclimate, determined technology by theforconsumption adopted of food farming & corresponding than crop products. This is because a live animal consumes a yields. See Table 1 to know the virtual water content of various andlot other agricultural of feed crops, products drinking water (Figure & service water 3). The estimated in its lifetime products percontribution of agriculture to the unit of consumption. 3 total water before use some it produces (6390 GmWith/yr) output. isstep every even bigger than suggested by earlier statistics due to the of food processing we loose part of the material as a result of inclusion selection &of green water inefficiencies. usewe The higher (use go upofinsoil water). If we include irrigation losses, which globally the product add up to about 1590 Gm3 /yr (Chapagain and Hoekstra, 2004), the total volume of water used 9 in agriculture becomes 7980 Gm3 /yr. About one third of this amount is blue water withdrawn for irrigation; the remaining two thirds is green water (soil water). The four major direct factors determining the water footprint of a country are: volume of consumption (related to the gross national income); consumption pattern (e.g. high versus Product Virtual water Reducing Springer content (liters) " Wastewater ' ☕ Worldwide, the vast majority of wastewater is neither collected ) nor treated (UNWWAP, 2017). Furthermore, wastewater % collection per se is not synonymous with wastewater treatment. In many cases, collected wastewater is merely * discharged directly into the environment without any + treatment. Agricultural runoff is almost never collected or $ treated, so that metrics for these types of wastewater flows. are practically non-existent. We can use freshwater more sustainably by cutting water - waste, raising water prices, slowing population growth, 1 & protecting aquifers, forests, & other ecosystems that 2 store freshwater (Miller & Spoolman, 2016). Although higher , prices for freshwater encourage water conservation, it make it # difficult for low-income people to buy enough water to meet / their needs. We can address this issue through the user-pays 0 approach, which give each household a set amount of free or & low-priced water to meet basic needs. When users exceed this amount, they pay increasingly higher prices as their water use increases. The government should also provide subsidies Table 1. Global average virtual water content of some products (Hoekstra & for improving the efficiency of water use. Withdrawing some of Chapagain, 2007). the subsidies that encourage inefficient water use & replacing them with subsidies for more efficient water use would sharply reduce water losses. That is, water prices could be higher for 10 commercial & industrial uses. their water use & water treatment costs. Even so, most industrial processes could be redesigned to use much less We can also improve efficiency in irrigation. The Table 2 below water (Table 3). shows some of the ways we can reduce wastewater in irrigation. Reducing Water Losses in Industries & Homes Redesign manufacturing processes to use less water Reducing Irrigation Water Losses Recycle water in industry Avoid growing thirsty crops in dry areas Fix water leaks Import water-intensive crops and meat Landscape yards with plants that require little water Encourage organic farming & polyculture to retain soil moisture Use drip irrigation on gardens & lawns Monitor soil moisture to add water only when Use water-saving showerheads, faucets, appliances, necessary & toilets (or waterless composting toilets) Expand use of drip irrigation & other efficient Collect & reuse gray water in & around houses, methods apartments, & office buildings Irrigate at night to reduce evaporation Raise water prices & use meters, especially in dry urban areas Line canals that bring water to irrigation ditches Table 3. Ways to reduce freshwater losses in industries, homes, and Irrigate with treated wastewater businesses (Miller & Spoolman, 2016). Table 2. Ways to reduce water losses in irrigation (Miller & Spoolman, Finally, as an individual, each of us can reduce our water 2016). footprints by using less water & using it much more efficiently. We can also cut freshwater losses in industries & homes. There are several more sustainable ways to use freshwater Producers of chemicals, paper, oil, coal, primary metals, & (Table 4). processed foods consume a lot of the freshwater. Some of these industries recapture, purify, & recycle water to reduce 11 Reducing Water Use & Waste Use water-saving toilets, showerheads, & faucets Water Pollution Take short showers instead of baths Water pollution is any change in water quality that can harm Turn off sink faucets while brushing teeth, shaving, or living organisms or make the water unfit for human uses such washing as drinking, irrigation, & recreation (Miller & Spoolman, 2016). It can come from single (point) sources or from larger & Wash only full loads of clothes or use the lowest dispersed (nonpoint) sources. Point sources discharge possible water-level setting for smaller loads pollutants into bodies of surface water at specific locations Repair water leaks through drain pipes, ditches, or sewer lines (Fig. 8). Nonpoint sources are broad & diffuse areas where rainfall Wash your car from a bucket of soapy water, use washes pollutants off the land into bodies of surface water. gray water, & use the hose for rinsing only Examples include runoff of eroded soil & chemicals such as fertilizers & pesticides from cropland, feedlots, logged forests, If you use a commercial car wash, try to find one that urban streets, parking lots, lawns, & golf courses. recycles its water Replace your lawn with native plants that need little if any watering Water lawns & gardens only in the early morning or evening & use gray water Use drip irrigation & mulch for gardens & flowerbeds Table 4. Some ways to reduce water use & waste. Individual efforts when taken collectively can make a huge impact (Miller & Spoolman, 2016). Fig. 8. Point source of water pollution from an industrial plant. Photo from nrdc.org. 12 Agricultural activities are by far the leading cause of water produced by coal-burning power plants, use of certain As- pollution (Miller & Spoolman, 2016). Sediment eroded from containing pesticides) agricultural lands is the most common pollutant. Other major agricultural pollutants include fertilizers & pesticides, bacteria In Bangladesh, groundwater used for drinking has been from livestock & food processing-wastes, & excess salts from contaminated with naturally occurring inorganic As. It is soils of irrigated cropland. Industrial facilities, which emit a estimated that of the 125 M inhabitants of Bangladesh variety of harmful chemicals, are a second major source of between 35-77 M are at risk of drinking contaminated water water pollution. Mining is the third biggest source of water (Smith et al., 2000). The primary drinking-water sources for pollution. Surface mining disturbs the land, creating major the patients were tube-wells, which drew groundwater. Tube- erosion of sediments & runoff of toxic chemicals. Another form wells have been used in Bangladesh since the 1940s. of water pollution is caused by the widespread use of human- However, the problem of As contaminated water has only made materials such as plastics used to make millions of recently come to light due to the increasing number of tube- products. Much of the plastic that is improperly discarded wells used over the past 20 years & the subsequent increase eventually winds up in waterways & in the oceans. In addition, in the number of individuals drinking from them. Historically, one of the major water pollution problems that we face is surface water sources (i.e. from rivers & lakes) in Bangladesh exposure to infectious bacteria, viruses, & parasites that have been contaminated with microorganisms, causing a can be transferred into water from the wastes of humans & significant burden of disease & mortality. Infants & children other animals. suffered from acute gastrointestinal disease resulting from bacterial contamination of stagnant pond water. Consequently, during the 1970s, UNICEF worked with the Case Study 1: Arsenic Bangladesh government to install tube-wells to provide what contamination of drinking-water in was presumably a safe source of drinking-water for the population. At the time the wells were installed, As was not Bangladesh recognized as a problem in water supplies, & therefore 4 Archives of Environmental Contamination and Toxicology (2018) 75:1–7 Arsenic (As) can get into water supplies in two ways: (1) standard water testing procedures did not include tests for through natural deposition such as volcanism As. Inin1993, action of oxygen led to a reasonable decrease & weathering, & As contamination organic car- Even worse are of skin water in tube-wells maligna (Guha Mazumder was et al. bon which was not observed with organic carbon of paddy 1998). Additionally, senso- andspatial vaso-motoric disorders are as part of the natural elements of the earth's crust; fields (2) (Neumann et al. 2010). The impact of observed, which can result in a collapse of the patient. of ground&waters confirmed. The map on Fig. 9 shows the distribution through industrial & agricultural pollution (e.g. BDOC coal burning, on the Cu of arsenic As mobilization contaminated groundwaters also was observed in in Bangladesh (BGS & DPHE, Both mobility and accumulation of arsenic strongly sediments of & Pb smelting, municipal trash incinerators, wood-preservingthe Mekong delta in 2001). Cambodia The (SeyfferthBangladesh et al. depend standard on the for As presence incompounds of its drinking in water is (50 the environ- 2014). This is of particular interest, asug/L) while both the the geological WHO guideline ment, is 10 i.e., its chemical ug/L. speciation. Examples are the inor- treatments, leaching from landfills containing As-laden ash and anthropogenic settings are quite different. Due to the ganic compounds arsenite [As(III)] and arsenate [As(V)], much higher population density in Bangladesh, anthropo- as well as the organic compounds monomethlylarsenite genic influences do have a much greater impact than in the [MMA(III)], monomethlylarsenate [MMA(V)], dimethyl- Mekong delta. Further and intense research activities will arsenite [DMA(III)], and dimethylarsenate [DMA(V)]. The 13 be necessary to clarify the relationship between the nature latter is transformed from the inorganic arsenic compounds and the impact of organic carbon on the mobilization and by biomethylation (Cullen and Reimer 1989). The order of thus the biogeochemistry of arsenic in Bangladesh and other toxicity of the compounds is as follows: MMA(III) > DMA contaminated regions. (III) > As(III) > As(V) > MMA(V) > DMA(V). The Toxicity of Arsenic Groundwater Contamination and Implications for Human Health The toxicity of arsenic has been knownFig. for centuries. 9. Map on Promi- the left shows the concentrations of As in shallow wells in nent examples are the arsenic poisonings of NapoleonABona- Bangladesh. survey ofThe problem 3,534 of groundwater well waters has shown contamination that waterby arsenic from 27%also parte and Arsenic ()..LgDescartes, L-1) as well as the German murderer of the shallowGesche concerns (