So here we have an example problem that wants us to indicate if the following environmental factors of aquatic biomes are physical or chemical. Notice that we've got these five different environmental factors of aquatic biomes listed below. We need to label each of them as either physical or chemical. A chemical aspect of the environment, as its name implies, refers to the presence, absence, amount, or composition of some chemical that's dissolved in the water. Whereas, the physical aspects refer to essentially everything else. You can think of it as the non-chemical characteristics of the environment that do not refer to the amounts or the compositions of chemicals.

Notice the first one here says salinity, and salinity refers to the amount of salt dissolved in the water. So, that is going to be a chemical aspect. The next one here says water depth, and the depth of the water literally is just referring to how deep we're looking into the water—how many meters below the surface of the water, if you will. This isn't referring to any specific presence, absence, or composition of a chemical. So the water depth is going to be a physical aspect of the environment.

Next, we have nutrient and oxygen concentration, and, of course, this refers to specific chemicals dissolved in the water. So this is going to be a chemical aspect. Light intensity refers to the amount or intensity of light, and light is not going to be dissolved in the water. Thus, light intensity is more so considered a physical aspect of the environment. The temperature refers to the average amount of energy and speed, the kinetic motion that the molecules have. It is not referring to the presence, absence, or composition per se. For that reason, this is also going to be a physical aspect of the environment.

That here concludes this example problem, and I'll see you all in our next video.