SCI 209

In Week Three we assess Chemical Oceanography.  We begin by looking at seawater and its chemical and physical properties. We also compare the methods by which scientists alter seawater. Finally, we identify the main types of marine pollution.   

Consider the reading and activities that you have completed this week. 

Which method of altering seawater do you find to be the most efficient? Why? What solution would you propose to reduce marine pollution?  

There are many populations of people on Earth who lack sources of clean drinking water. Fortunately, for some, scientists have devised several methods for desalinating seawater, which offers alternative sources of freshwater. Heat distillation involves boiling seawater using large amounts of heat energy. This process can be very expensive because of the electricity required to heat large quantities of water. It is more cost and energy efficient to use the waste heat of a power plant rather than generating that much heat energy just for the purpose of distillation. The evaporated water vapor is captured and condensed to form liquid water. Salt molecules are too large and heavy and are not evaporated along with the water vapor molecules. Solar distillation (solar humidification) is similar to the aforementioned process, but it does not require boiling of the seawater; instead it relies on the direct energy from the sun. This process would be beneficial for some who do not have the ability to heat large quantities of water, but the process is much slower because of the difficulty of concentrating sunlight into a small enough area to have accelerated evaporation. Our chapter also references electrolysis, reverse osmosis and freeze separation. Heat distillation is more efficient than electrolysis and could benefit countries who have already have seaside power plants. From our reading this week, it seems the most efficient method is reverse osmosis. New technology and materials will alleviate some of the problems with the membranes and will continue to allow this process to produce large quantities of fresh water in the future. With any of these processes, it is important to release clean, unpolluted water back into the oceans. There can be no by products that will increase marine pollution. Perhaps heat distillation and reverse osmosis could eliminate some of the pollutants from the sea water before returning the desalinated water into the ocean?