The Origin Of Water On Earth

From the 1960s through the 1980s, my Aunt Shirley was a third grade teacher in Lancaster County, Pennsylvania. After she retired, she gave me a copy of one of the science text books that she had used. In the section about water on Earth, there was a sentence that said “all of the water on the Earth has been here since it was formed.” My response to reading this sentence was a derisive chortle.

As any reader of Common Science or anyone who has taken a chemistry class will know, the products of combustion are water and carbon dioxide. Therefore, I could print this column out on a piece of paper, burn it to make new water molecules and thus disprove the statement in the old science book. How, I thought, could they have been teaching such incorrect information in my beloved home state? Upon reflection, my reaction to the book was a bit unjust. While my criticism was correct – I can make new water with a match and a piece of paper – as I will explain, the text book did get part of the story right.

There is a staggering amount of water on the Earth, 300 million cubic miles of it which cover 75% of the surface of our planet. With all of this water sloshing around, it is not surprising that people have been curious to know where it came from. It turns out that this question has sparked a fair bit of controversy over the years.

The story of water on Earth has its origins in the seconds after the Big Bang. During the first millisecond, all of the energy and matter in the universe coexisted in a sort of primordial plasma. As things cooled, matter began to take shape. Quarks formed which coalesced into protons, neutrons, and electrons, which then formed atoms. The first atoms formed were the smallest ones: hydrogen, helium, and a little bit of lithium.

Once hydrogen was formed, the universe was well on its way to being able to make water, but needed to wait for a while until oxygen would be available. Approximately one billion years after the Big Bang, the universe had cooled sufficiently to allow stars to form. Then fusion reactions within stars formed all of the larger atoms in the universe, such as carbon, nitrogen, lead, iron and, notably for this column, oxygen. Hydrogen and oxygen react easily to form water. Therefore, as soon as both were available, the universe became a much wetter place.

As even more time passed and the universe continued to cool, planets began to form, including the Earth, approximately 4.5 billion years ago. Among the molecules which coalesced to form the Earth there would have been a lot of water. That part of the story is undisputed. The controversy stems from the fact that, since the surface temperature of the Earth would have been approximately 230ºC at that time, many scientists have claimed that any water present would have boiled off and floated away into space.

If all the water present during the formation of the Earth had all wafted away, then, as the theory went, it must have been transported here afterwards. For decades, many scientists have suggested that water could have been brought to the Earth by a series of comet impacts, since comets contain a lot of frozen water. This theory has pretty much fallen by the wayside in recent months.

To understand why, first we need to talk about isotopes and atomic mass. Recall that an atom consists of a nucleus, which contains protons and almost always neutrons, surrounded by electrons. A particular type of atom contains the same number of protons and electrons. For example, all carbon atoms have six protons and six electrons. Most carbon atoms have six neutrons along with the six protons in their nuclei. The atomic mass of an atom is the sum of the number of protons plus the number of neutrons. Therefore, most carbon atoms have an atomic mass of 12. Some carbon atoms have eight rather than six neutrons, giving them an atomic mass of 14. Different types of the same atom with different numbers of neutrons are called isotopes and referred to by their atomic mass. For example, one could say, “the two most common isotopes of carbon are carbon-12 and carbon-14.”

Just like carbon, hydrogen also has isotopes. The nucleus of most hydrogen atoms consists of a single proton and thus has an atomic mass of 1. However, some hydrogen atoms contain one or two neutrons as well. Those with one neutron are called deuterium and those with two neutrons are called tritium.

In November of 2014, the European Space Agency landed a probe on a comet known as 67P. Among other interesting observations, the probe measured the ratio of the different hydrogen isotopes in the water which formed the ice crystals on 67P. The measurements showed that water which exists on comets contains a lot more deuterium and tritium isotopes than water on Earth. Given that the process for the formation of comets is consistent, we can safely assume that water on 67P is similar to the water on all comets. This result rules out comets as the water source for the Earth.

So if the newly formed Earth was really hot, 230°C, and comets didn’t bring water to the Earth, where did the oceans come from?

The answer comes from the fact that the boiling point of water is not constant but rather is dependent on pressure. For example, given the current conditions on Earth, water boils at 100°C at sea level. At higher elevations, such as Denver where atmospheric pressure is lower, water boils at 95°C. During the Earth’s early history, conditions, and thus atmospheric pressures, were much different.

While some disagreement remains, it appears likely that early in its existence, the Earth was struck by a large planetary body. The impact, often called the Big Splash, created the Moon and also contained enough energy to melt much of the Earth to create an atmosphere comprised primarily of carbon dioxide and melted rock vapor. The atmospheric pressure under these conditions was much, much higher than it is today, and thus prevented water from escaping even with the surface temperature of 230°C.

So while it may be that during the period of time between the formation of the Earth and the Big Splash that water was escaping the Earth’s atmosphere, afterwards it stayed put, cooled further and formed our oceans. This chain of events is not so very different from the description in Aunt Shirley’s science book. So let me officially apologize for my derisive chortle.

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Climate Change Harms Fresh Water Quality

A study published in Global Change Biology claims that the quality of fresh water is beginning to diminish in lower elevation forests, and that climate change is to blame.

The director of the Institute for the Environment, and distinguished professor of geography at the University of North Carolina at Chapel Hill, Lawrence E. Band, states that the lower elevated watersheds are becoming greatly stressed due to the recent frequency of droughts in those areas. “If we become more dependent on upper elevation catchments for our water supplies,” Band warns, “they become much more valuable.”

This study has been carried out by researchers from UNC, the University of Minnesota, the University of Georgia, and the U.S. Forest Service. The research is being conducted in the Southern Appalachian Mountains near the border of North Carolina and Georgia. Through studying the leaf-fall data of the low elevation areas and researching the diverse ecosystem of the area, these researchers have concluded that droughts brought on through drastic climate change is vastly affecting the availability of high-quality fresh water.

Chelcy Miniat of the US Forest Service and member of the research team states, “Water quality and quantity are two ecosystem services that are derived from forests. It is important to understand what affects these services, especially in the face of climate change and increasing U.S. population.”

UNC’s The Water Institute Celebrates World Water Day

As activists across the globe celebrate World Water Day on Saturday, UNC’s The Water Institute is working on campus and internationally to help make safe water and sanitation a reality for all people.

Dr. Jamie Bartram, Director of The Water Institute, is currently in Brisbane, Australia, delivering a keynote address for The International Water Centre’s: Water, Sanitation and Hygiene (WASH) International Conference.

Ashley McKinney, a Communications Specialist for the institute, says that Bartram and his team published a study which estimated that 28 percent of the world’s population, or 1.8 billion people, had used unsafe water in 2010. That estimate was one billion people more than the estimate by UNICEF and the World Health Organization.

“The study really questioned how you define what is safe water. It has really pushed the essence of who is living without safe water much higher,” McKinney says.

In response to the global water crisis, The Water Institute was created three years ago with two main missions: to teach and to research.

The institute, along with other partners, launched the ‘Water In Our World” campus-wide theme for 2012-2015 school years.

“The whole campus will be united around this academic theme of ‘Water.’ The goal really is to think about how each of us, and the choices that we make, can have an impact locally and globally,” she says.

The theme for World Water Day this year is “Water and Energy.”

“We need to really think forward. We need to think ahead. Of course the demand for water is increasing widely. The demand is increasing because the population is increasing. The demand for fresh water and energy will continue to increase over the coming decades. It will put a lot of challenges and strains on our resources,” McKinney says.

World Water Day has been observed since 1993 when the United Nations General Assembly declared March 22 as the global day of awareness for clean water.

McKinney explains The Water Institute holds three conferences annually to bring together people from diverse disciplines to tackle water and public health issues.

In 2010, the institute launched the “Water and Health: Where Science Meets Policy” conference. In 2013, more than 500 researchers, policy-makers, students and entrepreneurs from 45 countries attended the event.

In March, the institute launched the first “Nexus 2014: Water, Food, Climate and Energy Conference.” And, coming up on May 5 through May 7, the institute is hosting the 2014 Water Microbiology Conference.

McKinney adds there are ways the community can contribute.

On March 26, the Aveda Institute on Franklin St. is hosting a “Cut-A-Thon” from 9:00 a.m. to 6:00 p.m. McKinney says all donations go to The Water Institute in efforts to support the clean water initiative.

Water Contamination Notice Issued For North Chatham

A water system malfunction in Chatham County has authorities urging residents to boil their water, according to the News and Observer.

Areas directly affected include Fearrington Village, Briar Chapel, Hudson Hills, Galloway Ridge, Woods Charter School, Manns Chapel, Hamlet Grove, Prestonwood, and Monterrane.

The issue was first noticed when reports of low water pressure and outages came in from residents. Those problems could allow bacteria to get into the water pipes.

The cause of the malfunction is under investigation, but an official told the N&O that boiling water for one minute should eliminated any disease-causing bacteria.

The warning will remain in place until a written notice is delivered.

UNC System Cuts Energy/Water Costs By 20/40%

CHAPEL HILL – The UNC Board of Governors is working to cut energy and water costs for the schools to make a more efficient system and President Tom Ross says the schools are making small changes to save big.

“You may recall that our strategic plan identifies some key areas of work, like including energy-related research, analysis, instruction, and outreach, where with targeted investments UNC, we believe, can make a real and meaningful difference,” Ross says.

The UNC system averages $225 million per year on energy and water costs.  Since last year the university system has saved $63 million in energy costs and $13.7 million in water costs.  Since the 2002-2003 school year the total equals $297 million in savings.

System wide, the schools have managed to cut electricity by 20 percent and water by 40 percent, and President Ross says there are more plans to continue making the University more efficient.

“To date, this board has authorized 15 guaranteed energy performance projects across the system,” Ross says. “Ten of these projects are currently under contract producing energy savings of more than $10 million per year.”

Current energy sources can be costly in terms of money and for the environment.  The UNC system has often been at the forefront of innovation and new ideas, and energy is no different.  Ross says that UNC will stay at the forefront when dealing with energy and water to improve the system.

“Recognizing that most sources of easily accessible energy are limited and that many are non-renewable, the plan calls for UNC to be in the forefront, in collaboration with private industry and non-profit organizations and making discoveries that will fuel our state and the world in the future,” Ross says.

The University schools have worked to reduce costs of energy and water by substantial amounts.  However, Ross says that they will continue to work and cut costs for expenses like water and energy.

“But we know we can do more, and we have as a collective goal in our university system to save $1 billion over the next 20 years in water and energy costs,” Ross says. “And while the financial savings are important, we will also be helping to preserve our natural and environmental resources for future generations. “Water, for example, is, we believe, the new precious metal, and we have to be sure its preserved as a public asset and that we protect our water supplies and find new ways to reduce consumption.”

UNC has implemented many ways to conserve water, like grey water in the bathrooms.  The University says plans like these will continue to appear as it works to conserve resources.

Beat the Heat- Hydrate!