Chapter 7 Ocean Chemistry课件.ppt

Chapter 7 Ocean Chemistry;Water is a powerful solvent and we have it everywhere – the hydrological cycle;Ocean Salinity;Fig. 6-14, p. 167;Mid Ocean Average Surface Salinity;Surface Salinity Northern Hemisphere Summer;Fig. 7-3, p. 189; Dissolved salts Major constituents and trace elements Conservative/nonconservative constituents;A few ions (charged particles) account for most of the salinity of the oceans. ;Regulating the major constituents in seawater;Residence time: the average time a substance remains in solution in the ocean Total amount divided by rate of input (or output);The ratio of dissolved solids in the ocean is constant: Well-mixed solution Principle of Constant Proportions : the ratios between the concentrations of major conservative ions in open-ocean water are constant ;Salt composition constant for last 1.5 billion years 5*1022g= total dissolved material 2.5*1015g=total run off per year salinity is not increasing! therefore: rate of addition ~ rate of removal;salinometer;Seawater’s constituents may be conservative or nonconservative Conservative = concentration changes only as a result of mixing, diffusion, and advection Non-conservative = concentration changes as a result of biological or chemical processes as well as mixing, diffusion, and advection;Distribution with depth Photosynthesis removes CO2 and produces O2 at the surface Respiration produces CO2 and removes O2 at all depths Compensation depth (Photosynthesis = Respiration) CO2 O2;Oxygen and CO2 profiles;metric tons C (106);Some words to keep in mind: Ion – charged atom cat-ion (+) – positively charged ion an-ion (-) – negatively charged ion Dissociation = to break apart into ions OH- H2O (all 3 will be in water solutions) H+ ;Non-pure water solutions;;Seawater;CO2 combines readily with seawater to form carbonic acid (H2CO3). Carbonic acid can then lose a H+ ion to become a bicarbonate ion (HCO3