Because water has different colors in different places

The color of the water provides us with information on its content.

Which image comes to mind when you think of water? A cold and refreshing drink? A crystalline blue ocean that extends to the horizon? A lake that reflects the mountains? Or a small and dark pond?

You would probably be more instigated to swim in some of these waters than in others. And those who seem more clean would probably attract you more.

Even if you don’t know, you are applying concepts of physics, biology and chemistry to decide whether to make an immersion.

The color of the water provides us with information on its content. As an engineer who studies water resources, I thought about how I can use the color of the water to help people understand how contaminated the lakes and beaches are and if they are safe to swim and fish.

The light and color of the water

Drinking water usually seems clean, but lagoons, rivers and oceans are full of floating particles. They can be small fragments of land, rock, plant material or other substances.

These particles are generally brought to water during storms. All the rain that falls and is not absorbed by the ground turns the floods, dripping down the hill and transporting melted materials along the road until you reach a water body, like a river, a lake.

The particles present in the water interact with the sun radiation that focuses on the surface. They can absorb this radiation or reflect it in another direction, in a process known as dispersion.

What we see with our eyes is a fraction of radiation that is reflected by the surface of the water. This considerably affects our perception of water, including its color.

Depending on the properties of the particles in the water, they will absorb and disperse the radiation in different wavelengths. The wavelength of the light determines the color we see in the water.

In waters with large quantities of sediments, such as the Missouri river in the United States, nicknamed the “great sludge”, the light that affects is reflected with shades ranging from yellow to red. This makes water seen orange and cloudy.

In cleaner and purer waters, the light is reflected in the shadow of blue, which shows us this color.

A well -known example is the crater of the lake in Oregon, which is located in a volcanic crater and is fueled only by rain and snow, without receiving sediments.

The deep waters, like those of the lake crater, usually have a dark blue tone, while shallow and clearer waters, like the Caribbean islands, appear in a tone of turquoise. This is because the light is reflected in the white and sandy background.

When the water contains a lot of plant material, chlorophyll (a pigment that plants produces on their leaves) absorbs blue light and reflects the green light.

This usually happens in the waters that receive flows from very urbanized areas, such as Lake Okeechobee, near Miami, Florida.

This flow contains fertilizers of farms and gardens, composed of nutrients that guide the growth of plants in the water.

Finally, some waters have a large amount of organic matter dissolved by decomposition organisms and plants, as well as human and animal waste.

This can happen in forest areas with many wildlife and densely populated areas, where waste water is downloaded in waterways and rivers.

This material absorbs most of the radiation and reflects very little light, which makes water dark.

Growth of harmful algae

Scientists expect water in nature to contain sediment, chlorophyll and organic matter. These elements help to support all living organisms in the water, from the small microbes to the fish we eat. But the excess of some of these substances can become a problem.

For example, when the water contains many nutrients and heats up on sunny days, the growth of plants can escape control.

Sometimes this leads to excessive growth of harmful algae, forming columns of toxic algae that can cause diseases in people swimming in the water or consume the derives that derives from it.

When the waters are thus polluted to threaten fish, plants and people who consume it, state and federal laws (USA) determine governments to act to clean them. And the color of the water can help guide these efforts.

My students and I collected water samples on High Rock Lake, a popular place for swimming, boat and fish in the center of the North Carolina.

Due to the high levels of chlorophyll, the growth of algae has become increasingly common, which generates concern in residents and visitors, who are afraid that these proliferations will become harmful.

Using the satellite images of the lake and the data of the samples we have collected, we can generate water quality maps.

State authorities use these maps to monitor chlorophyll levels and observe how they vary in time and space. This information can help notify the population of algae excessively and create new rules to make the water cleaner.

*Courtney Di Vittorio is an engineering professor assistant at Wake Forest University in the United States.

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Source: Terra

Ben

Ben Stock is a lifestyle journalist and author at Gossipify. He writes about topics such as health, wellness, travel, food and home decor. He provides practical advice and inspiration to improve well-being, keeps readers up to date with latest lifestyle news and trends, known for his engaging writing style, in-depth analysis and unique perspectives.