《环境化学》课程PPT教学课件讲稿（英文版）Unit 11 Properties of Water

Properties of Water

Properties of Water

Water content of selected organism and foods of mass of mass Marine 97 Broccoli 90 invertebrates Human fetus 93 Milk 88 (1 month) Fish 82 Apples 85 Human adult 70 Grapes 80 Eggs 75

Water content of selected organism and foods % of mass % of mass Marine invertebrates 97 Broccoli 90 Human fetus (1 month) 93 Milk 88 Fish 82 Apples 85 Human adult 70 Grapes 80 Eggs 75

Distribution of water on the earth Saline lakes (. 003% 0.01 Oceans 97.2% Polar ice Freshwater d 2.8% glaciers 0.3% 2% Saltwater 0.12% 0.167% Underground water Only a small percentage(<3%)of water on Earth is fresh water. Lakes and rivers account for just Over0 1% of the earth's total water

Distribution of Water on the Earth Only a small percentage (<3%) of water on Earth is fresh water. Lakes and rivers account for just 0ver 0.1% of the earth’s total water

Global water use(1900-2000) s00 49 4500 4000 3.500 Agricultural use 奥3 2.000 1500 L000 50 d Domestic use 19001920194019601980 2000

Global water use (1900-2000)

Hydrologic cycle Evaporation (hal formation Transpiration Precipitaton wapor Condensation Precipitation Processes that cycle water between air and earth surface

Hydrologic cycle Evaporation Transpiration Condensation Precipitation Processes that cycle water between air and earth surface

Evaporation and transpiration HyO Hyo (rain or 以4 4,, H HO Transpiration is a process in which water escapes through the pores on leaf surfaces

Evaporation and transpiration Transpiration is a process in which water escapes through the pores on leaf surfaces

Composition of natural waters Fresh water: dissolved solids <0.1% Drinking water standard: dissolved solids <0. 05% Major constituents: Ca2+, Mg2+, HCO3 Sea water: dissolved solids N3.5%(Dead sea: 25%) Major constituents C- 9,000ppm Na* 10, 600 ppm SO4- 2, 600 ppm Mg2+ 1, 300 ppm HCO3 140 ppm Ca2+ 400 ppm Br- 65 ppm 380 ppm

Composition of natural waters • Fresh water: dissolved solids <0.1%. – Drinking water standard: dissolved solids <0.05% – Major constituents: Ca2+, Mg2+, HCO3 - . • Sea water: dissolved solids ~3.5% (Dead sea: 25%) – Major constituents Cl- 19,000 ppm Na+ 10,600 ppm SO4 2- 2,600 ppm Mg2+ 1,300 ppm HCO3 - 140 ppm Ca2+ 400 ppm Br- 65 ppm K + 380 ppm

Water as solvent and as ecosystem e Water is a remarkable solvent dissolves and transports a wide range of materials Interacts with soil and particles and gases in the air Water houses ecosystems A large percentage of the biosphere lives in some form of aqueous environment Water quality is often defined in terms of the ability of the aqueous environment to support the normal ange of biological species

Water as solvent and as ecosystem • Water is a remarkable solvent, – dissolves and transports a wide range of materials. – Interacts with soil and particles and gases in the air • Water houses ecosystems. – A large percentage of the biosphere lives in some form of aqueous environment. – Water quality is often defined in terms of the ability of the aqueous environment to support the normal range of biological species

Water molecule and hydrogen bonding Oxvgen … Hvdrogen bonds Hydrogen la H-bonds have a profound effect on the physical properties of water in both its liquid and solid states

Water molecule and hydrogen bonding H-bonds have a profound effect on the physical properties of water in both its liquid and solid states

Boiling point and melting point FREFZING POINIS 34 HaTe Without H-bonds, water would be a gas at the temperature found on earth and our form of life and environment would not be possible

Boiling point and melting point Without H-bonds, water would be a gas at the temperature found on earth, and our form of life and environment would not be possible