Water Chemistry Notes Mr. Distasio

Carbon Dioxide (CO 2 ) Colorless, odorless gas Source: Respiration Removal: Photosynthesis Highest Levels: at night, on cloudy days and at high temp. Fish Tolerance: 20 ppm or mg\L H 2 O + CO 2  HCO 3 (carbonic acid)

Chlorine (Cl) Greenish- yellow, poisonous gas (Free Cl - short term) Dissolves in H 2 0, combines with decaying material to form trihalomethanes - persistent & carcinogenic Sources: pools, sewage treatment, textile industry. 0.5 ppm kills bacteria,.37 ppm max for fish (coats gills) Becomes more poisonous as pH drops Chlorides are salts containing Cl and metal (CaCl, MgCl, NaCl) Tests: Free: only measures Cl dissolved in H 2 O Total: measures free Cl and combined

Dissolved Oxygen (DO) Sources: Rapids, diffusion from atmosphere, photosynthesis 75% of the world's O 2 comes from phytoplankton Reasons for low O 2 : Algae blooms (fertilizer runoff, sewage) High temperature High cloud cover High bacteria, Aquatic Animals Desirable: 5-18 ppm : < 3 = All fish die Fish use more oxygen when the H 2 O is warmer eg. 77`F =300 mg\hr 40`F= mg\hr

H 2 O Hardness Calcium (Ca) and Magnesium (Mg) Natural Source: Limestone (CaCO 3 ) Limestone is dissolved by acidic H 2 O (Releases CO 2 ) < 250 ppm to drink Specific amounts are necessary for exoskeletons & bone development Soft H 2 O= 0-60 mg\L = Makes nonmetals (like Ammonia) more toxic = increases rate for heart attacks in humans = Better to wash clothes in Hard H 2 O = mg/L Carbonates = Act as buffers to neutralize acids H 2 SO 4 + CaCO 3  H 2 CO 3 + Ca H 2 O + SO 3  H 2 SO 4 (in acid precipitation)

Nitrates and Nitrites (NO 4, NO 3 ) Inorganic: Ammonia, gaseous N Organic (contain C): Amino Acids (Recycled plants and animals) Source: fertilizer runoff, sewage Excessive phytoplankton uses up O 2 in decomposition process "Brown Blood disease" - in fish with high nitrites Blue Baby syndrome - humans, cannot transport O2 Nitrates converted to nitrites Intestines ("Toxic Shock") (dangerous)

Phosphates (PO 4 ) Sources: soil, pesticides, rocks, detergents, organic waste Increases plankton growth when concentrations are too high..025 mg/L necessary for eutrophication : < 0.1 ppm desirable

pH acidic basic 0 14 Potential for Hydrogen ions [H+] Each unit represents a 10x change in [ ] best for fish Older lakes are more acidic due to decomposition & eutrophication Hg, Pb, Al (metals) become more toxic in an acidic environment. Acid precipitation " = PA #1 in USA, H 2 SO 4 and HNO 3 (see notes)

Other chemical parameters Zn = 5.0 max Cu = 1.0 max Detergents = <0.5 max Fe = 0.3max Pb = 0.05 max Al = < 0.05 max Silica = <60 ppm desirable Cadmium = 0.01 max NH 4 = 0.06 max Alkalinity (Desirable 110 ppm) - a measure of the buffering capacity for a water sample

Synergistic effect - Two or more substances combine to produce greater effects than their sum >2 Eutrophication – aquatic succession Titration – a chemical test used to determine the concentration of a given substance found in a solution.