You may
think of rainwater as an ultra pure form of water, but this is not actually
true. While high in the atmosphere, the
water droplets interact with numerous gases, which dissolve in the water
droplets before they fall to the ground.
Carbon dioxide (CO2) is the most important of these gases, as
it combines with water to form carbonic acid (H2CO3),
which is a small component of rainwater.
This small amount of carbonic acid causes natural rain to be slightly
acidic. But most other kinds of water
such as seawater, river and lake water, and water in the ground is slightly
basic, the opposite of acidic. How does
this transformation occur?
The answer lies in the fact that as
rainwater flows down through the soil and rocks on its way to the ocean, it interacts
with rocks in a process called “chemical weathering”. A major weathering reaction involves the
breakdown of the mineral calcite (CaCO3) by the acidic rainwater,
releasing calcium (Ca+2) and bicarbonate (HCO3-)
ions. The bicarbonate ion is slightly
basic, changing the water into a slight base.
This is a necessary process, as most aquatic and marine life could not
survive if the water were acidic like rainwater.
A lot of weathering reactions are
poorly understood however, and while I was an undergraduate, I undertook
research with a graduate student named Hyojin Kim to better understand how
water changes as it flows from cloud to stream to ocean. The site we studied was in a nature preserve
in Northern California, in the watershed of the Eel River.
The Location of Rivendell, the site we studied, within California the wells drilled are shown
The Elder Creek, which sits at the bottom of our hill slope and has basic water
We drilled
wells into the hill slope and devised a suction system to sample the
groundwater from these wells everyday for several years. We then analyzed these water samples for many
kinds of ions.
One of our auto sampling machines on the steep hill slope
The data
showed us that chemical weathering is a complex and dynamic process. Weathering reactions of all sorts of
different minerals made the groundwater chemistry change throughout the year
and up and down the hill slope. We
monitored the rainwater and creek water at the site to show how much the water
had changed during its time flowing through the soil and rock. Our data showed that different ion
concentrations vary differently throughout the year and across multiple years,
demonstrating that groundwater chemistry is a complex system waiting further
exploration.
Very clear language used throughout, and a nice general intro to the chemical weathering process. I don't know if it would be necessary to try to explain what is an acid, a base, and an ion, but maybe (harder for me to judge since this is all very familiar to me).
ReplyDeleteOne question--did you come across an elves in Rivendell?
This is a very nice simplification for me, a grad student that is vaguely familiar with geochemisty/chemistry, but my grandparents wouldn't understand this. The language is mostly very simple, but I wouldn't have included any chemical formulas, nor used many of the terms you used.
ReplyDeleteHow does water "transform?"
What is "chemical weathering?"
What's an "ion?"
What is a "system?"
This is a very nice simplification for me, a grad student that is vaguely familiar with geochemisty/chemistry, but my grandparents wouldn't understand this. The language is mostly very simple, but I wouldn't have included any chemical formulas, nor used many of the terms you used.
ReplyDeleteHow does water "transform?"
What is "chemical weathering?"
What's an "ion?"
What is a "system?"
Both the language and story are easy for me to follow. All the chemicals have their formulas, makes it easier for me to understand. I think we all kind of underestimated the knowledge level of grandparents, word like transform and system shouldn't be too hard to follow.
ReplyDeleteI liked that this was short and to the point - with lots of easily understandable pictures. I think the length makes it more approachable and less intimidating.
ReplyDeleteThis was a great undergraduate experience and generally well written and aimed for the general audience. Almost all of the language was accessible. I am interested to hear in the blog how the ion concentrations changed with relation to season, rainfall, etc. Give us some understanding of the results of the study more than general motherhood statements about the big picture.
ReplyDeleteI liked it, and found it easy to understand despite having only a few college intro chemistry courses. I would think this would have all kinds of applications and also ramifications to people, and would have liked to see more said about that, to show the relevance explicitly.
ReplyDeleteThis is really accessible and straightforward but maybe explain the topo map a little bit more. Most people probably aren't familiar with topographic maps and explaining what the map shows more clearly may help.
ReplyDeletei would try to make a little analogy about CO2 and how thats an emmission from cars, ect. to give my grandmother a perspective and an idea of what that gas even is. Also...why do we have to explain it to our grandmother....is our grandpa supposed to be smarter....?
ReplyDeletei would try to make a little analogy about CO2 and how thats an emmission from cars, ect. to give my grandmother a perspective and an idea of what that gas even is. Also...why do we have to explain it to our grandmother....is our grandpa supposed to be smarter....?
ReplyDelete