by Curious Kids is a series for children of all ages. If you have a question you want to answer from an expert, send it to curiouskidsus@theconversation.com.
Why are water different colors in different areas? – Gina T., 12 years, Portland, Maine
What do you imagine when you think of water? An icy, refreshing drink? A crystal blue ocean that extends to the horizon? A lake that reflects majestic mountains? Or a small pond that looks dark and cloudy?
They would probably be more excited to swim in some of these waters than in others. And those who appear cleanest would probably be the most attractive. Regardless of whether you recognize it or not, use concepts in physics, biology and chemistry to decide whether you should jump into it.
The color of the water provides information about what is in it. As an engineer who studies water resources, I think about how I can use the color of water to understand people how dirty lakes and beaches are and whether they are safe for swimming and fishing.
Light and the color of the water
Drinking water usually looks clear, but ponds, rivers and oceans are filled with floating particles. It can be tiny fragments of dirt, rock, plant material or other substances.
These particles are often worn into the water during the storms. Every precipitation that hits the floor and does not go into the ground flows, flows downhill until it reaches an open water and absorbs loose materials on the way.
Particles in the water interact with radiation from the sun, which shines on the water surface. The particles can either absorb this radiation or reflect in a different direction – a process that is referred to as scatter. What we see with our eyes is the fraction of the radiation that is scattered again from the water surface. It strongly influences how water looks for us, including its color.
Depending on the properties of the particles in our water sample absorbed and it scores the radiation at different wavelengths. The wavelength of the light determines the color we see with our eyes.
Water that contains a lot of sediment – like the Missouri River, named the nickname “Big Muddy” – back lamp over the yellow to the red. This makes the water appear orange and muddy.
Cleaner, pure water shears in the blue area, which makes it look blue. A famous example is Crater Lake in Oregon, which is located in a volcanic crater and is fed by rain and snow without streaming sediments.
Deep waters like Crater Lake look dark blue, but flat water that are very clear, such as in many Caribbean islands, can be light blue or turquoise. This happens because light reflects from the white, sandy soil.
When water contains a lot of plant material, chlorophyll – a pigment plants in their leaves – absorbs blue light and a green light. This often happens in areas that contain a lot of drain from highly developed areas such as Lake Okeechobee in Florida. The drain contains fertilizers from farms and lawns consisting of nutrients that cause plant growth in the water.
After all, some water contains a lot of material, which is referred to as organic substance that is triggered in terms of color-frequently from decomposing organisms and plants as well as human or animal waste. This can be done in forested areas with a lot of animal life or in heavily populated areas that release wastewater in streams and rivers. This material mostly absorbs radiation and backlights very little light in the spectrum, so that the water looks very dark.
Bad flowers
Scientists expect water to contain sediments, chlorophyll and organic substance in nature. These substances help to maintain all living organisms in the water, from tiny microbes to fishing that we eat. But too much good can be a problem.
For example, if water contains many nutrients and heats up on bright, sunny days, plant growth in the water can get out of control. Sometimes it causes harmful algae flowers – springs of toxic algae that people can make very sick when they swim in the water or eat fish that came from it.
If waters are so dirty that they threaten fish and plants, or people who drink water, state and federal laws, governments have to clean up them. The color of the water can help to guide these efforts.
My students and I collect water samples at High Rock Lake, a popular place for swimming, boating and fishing in Central North Carolina. Due to high chlorophyll levels, algae flowers occur more often. Residents and visitors fear that these flowers become harmful.
We can create water quality cards with satellite photos of the lake and our sampling data. State officials use the cards to pursue chlorophyll levels and see how they change in space and time. This information can help you to warn the public when algae flowers are present and develop new rules to make the water cleaner.
Hello, curious children! Do you have a question you want to answer from an expert? Ask an adult to send your question to curiouskidsus@theconversation.com. Please tell us your name, your age and the city where you live.
And since curiosity has no age limit – adults, let us know what they are wondering. We will not be able to answer every question, but we will do our best.
This article will be released from the conversation, a non -profit, independent news organization that brings you facts and trustworthy analyzes to help you understand our complex world. It was written by: Courtney di Vittorio, Wake Forest University
Read more:
Courtney di Vittorio receives funds from the North Carolina Attorney General Environmental Enhancement Grant Program (Award WFU021PRE1) to collect data at High Rock Lake, NC. She is connected to the Yadkin Riverkeepers, a non -profit group of the environmental representative and the North Carolina Lake Management Society.
