This picture shows a scientist on a research ship. He is getting ready to lower some instruments into the ocean. These instruments measure the chemistry of the ocean.
Click on image for full size
Image courtesy of NOAA, photograph by Captain Robert A. Pawlowski.
The oceans are full of water. Ocean water is not just pure water, though. Ocean water has many different chemicals in it, especially salt.
The salt in sea water is a lot like the salt we sprinkle on food. Sea salt has other chemicals in it too. The main other chemicals in sea salt are magnesium, sulfate, calcium, and potassium.
Why is the ocean salty? When it rains on land, some of the water dissolves minerals in rocks. That water flows in rivers to the sea. It carries the minerals with it. When the water evaporates back out of the ocean, it leaves the minerals behind. The minerals make sea water salty.
Some parts of the ocean have more salt than others. For example, melting glaciers dump lots of fresh water into the ocean. Places in the ocean near melting glaciers aren't as salty as the rest of the ocean.
Some gases are dissolved in sea water too. There is carbon dioxide (CO2) from the atmosphere dissolved in sea water. That is important because carbon dioxide is a greenhouse gas. Scientists want to know how much carbon dioxide the oceans can hold. It will help them predict climate change. When carbon dioxide dissolves in water, it makes an acid. Too much acid can harm corals, shellfish, and other creatures that live in the seas.
People and other living things can also change the chemistry of the oceans. If farmers use too much fertilizer, some of it gets washed into rivers. The rivers carry the fertilizers to the sea. Some tiny creatures in the ocean love the nitrogen from the fertilizer and grow like crazy. As they grow, they use up lots of oxygen. When large areas of the ocean lose oxygen, fish and crabs and other animals die.
Shop Windows to the Universe Science Store!
The Spring 2010 issue of The Earth Scientist
, focuses on the ocean, including articles on polar research, coral reefs, ocean acidification, and climate. Includes a gorgeous full color poster!
You might also be interested in:
Raindrops form when tiny water droplets collide together in clouds to form bigger ones. When they get too heavy, rain falls out of the clouds. Rain is more than 5mm in diameter. The types of clouds that...more
Minerals are the building blocks of rocks. There are many different types of minerals. All of them are solid and all are made of atoms of elements. Minerals can grow even though they are not alive. Most...more
Almost 3/4 of the Earth is covered with water. Almost all of that water is in the oceans. Have you ever been swimming in the ocean? If you have and you accidentally got water in your mouth, you know the...more
This page is not yet developed at the elementary level. Please check back for updates or click on the "Intermediate" button above for information....more
Carbon dioxide (CO2) is a kind of gas. There isn't that much carbon dioxide in Earth's atmosphere, but it is still very important. Carbon dioxide is a greenhouse gas. That means it helps trap heat coming...more
Only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases. But they have a huge effect on climate. There are several different types of greenhouse gases, but they all have something in...more
Not all of the energy from the Sun that arrives at Earth can leave easily. After being transformed into heat, it can become trapped by certain gases in the air. This is a natural process called the greenhouse...more