Shown below are the results of water quality analyses of the Thames River in London. If the water is treated with 58.5 mg/L of alum to remove turbidity, how mu (mg/L as CaCO3) alkalinity will remain? Ignore side reactions with phosphorus and assume all alkalinity is HCO3. Constituent Milligrams per litre Expressed as CaCO3 260.0 Total hardness Calcium hardness CaCO3 235.0 Magnesium hardness CaCO3 25.0 Total iron Fe 1.8 Copper Cu 0.05 Chromium Cr 0.01 Total alkalinity CaCO3 130.0 Chloride Ci 52.0 PO4 1.0 Phosphate (total) Silica SiO₂ 14.0 Suspended solids 43.0 Total solids 495.0 pH₂ 7.4 "Not in mg/L.

Poorly treated municipal wastewater is continuously discharged directly into a lake. The discharge from the wastewater plant into the lake occurs at a flow of Qd = 1 m3/hr. The concentration of phosphate (PO43, M = 95 g/mol) in the discharge flow (Cxd) that is decaying with first-order kinetics is 100 mg/L. The lake is a well-mixed water body of 100 m3. (Phosphate is naturally uptaken by algae with a first- order decay rate constant equal to 0.20/day.) The concentration of phosphate in the incoming river (Cx,r) is 10 mg P/L. The incoming river flow rate is Q, = 10 m3/hr. %3D a) Which of the following equations represent the correct mass balance equation? O va = CxQr - CxdQd -QoutCxvout" kCx,outV %3D O 0 = Cx,Qr + CxdQd -QoutCxvout" kCx,outV X,r O 0 = CxQr + CxdQd -QoutCxvout- kV O 0 = Cx,dQr + Cx,,Qd -QoutCxout- kCxoutV

Calculate the alkalinity of a water containing 10−4.5 M total carbonate at pH 11. Express your answer in units of mg/L–CaCO3. State all relevant assumptions.

6. Identify the two species within the carbonate system that are the most relevant to the following situations, and identify the associated equilibrium constant: a. Dissolution of an Alka-Seltzer tablet (sodium bicarbonate, citric acid, aspirin) in water to create an effervescent pain-relieving drink. b. The effects of ocean acidification on the health of coral reefs.