ENGR 0011
R09
Engineering and the Nitrogen Cycle
Nick DeLuca (ncd8@pitt.edu)
know the demise of the world that may come from this cycle
will not affect me, but somewhere in the future people will
be affected by the deteriorated ozone layer and I want to
help them out.
INTRODUCTION: WHAT IS THE
NITROGEN CYCLE?
What is the most abundant element in our
atmosphere [1]? What element is absolutely necessary in
allowing plants to process food? What element is also an
essential component of a nucleotide? The answer to all
these questions is nitrogen. The nitrogen in the air,
unfortunately, is not ready at any point to be used by living
organisms. The chemical processes of microbes and
lightning strikes produce the energy needed to break up the
nitrogen molecules and allow living things to use them [2].
This is a part of something called the nitrogen cycle. “The
nitrogen cycle is the process whereby nitrogen passes from
the atmosphere into living things and ultimately back into
the atmosphere.” [1] The nitrogen cycle is very important in
the sustainability of life, and humans need to limit producing
too much nitrogen, which would unleash the dangers that
appear when there is too much of it.
STEPS IN THE NITROGEN CYCLE
In establishing a basis for what exactly the nitrogen
cycle is, it is important to understand the five 5 steps of this
cycle. They are nitrogen fixation, nitrification, assimilation,
ammonification, and denitrification.
The first step of the nitrogen cycle is called
nitrogen fixation. Nitrogen fixation is a process that
involves gaseous nitrogen (N2). It “is converted to ammonia
(NH3 or NH4+) via biological fixation or nitrate (NO3-)
through high-energy physical processes.” [3] As I stated
earlier, the nitrogen in the air (N2) is very stable and cannot
be used by living things unless it is converted to a different
form. This is the major part of the cycle and will be what the
majority of this paper will be about.
Nitrification is next and is a two-step process.
During this, NH3/NH4+ is converted to NO3-. During the
first step, the soil bacteria Nitrosomonas and Nitrococcus
convert NH3 to NO2-. The second step involves another soil
bacterium, Nitrobacter, it oxidizes NO2- to NO3-. [3] The
bacteria stated here, gain energy through this process. They
need oxygen in order to survive [3].
Assimilation is the process where the NO3- and
ammonia that is formed through the first two steps of
nitrogen cycle is absorbed by plants and animals. [3] Plants
receive the nitrogen through their roots, while animals
absorb the nitrogen through plants’ tissues [3].
Ammonification is the forming of ammonia from
organic nitrogen. This ammonia is propelled into the
environment and is then available for the steps of
nitrification or assimilation. [3] This process allows for large
quantities of organic nitrogen, including proteins, amino
acids, and nucleic acids to be produced [3].
Denitrification is the forming of N2 from the
elimination of NO3- by anaerobic bacteria. [3] This only
occurs where there is very little oxygen. It can be deep in
the soil in areas such as wetlands [3]. This is a process we
need to increase, but do so safely.
Why am I Researching the Nitrogen Cycle?
The Nitrogen Cycle is an important issue in the area
of chemical engineering. I am majoring in that field and one
day may try to solve this issue. While trying to understand
what the nitrogen cycle is, I also need to look two more
ideas. First, what is the ethical way or the proper way of an
engineer to solve this problem or any other problems?
Second, is researching an engineering problem useful to the
freshman engineering curriculum at Pitt and worldwide. In
this paper I will discuss problems of the nitrogen cycle
currently such as why humans are disrupting it, what
engineers can do to help this problem using the code of
ethics, can evaluating engineering problems through writing
actually help the field of engineering in the long run, some
various “dark sides” to nitrogen, the various steps of the
cycle, ways cattle can “excrete nitrogen across a pasture.”
Through this paper I want people to know what the nitrogen
system is and explain how the problem in this system is
affecting all of us. As I said earlier, one day I may be
looking into this problem through being a chemical engineer.
That is the reason I chose this topic and just reading about it
in some of my sources made me really interested in this. I
University of Pittsburgh, Swanson School of Engineering
10/9/12
1
Nick DeLuca
Impact Cattle can have on the Nitrogen Cycle
THE PROBLEM: HUMAN PRODUCTION
OF TOO MUCH NITROGEN
I mentioned briefly earlier that animal excretion
really also has a major impact on the nitrogen cycle. When
animals such as cattle eat, they take in a lot of nitrogen. This
nitrogen is then excreted through their urine into the ground.
It gets into the soil and some of this nitrogen can form into
nitrous oxide [5]. As already stated, this nitrous oxide is a
bad greenhouse gas. Farmers need to try to find a way to
control cattle urine, and this can change the nitrogen cycle in
a very positive way.
I really like the saying “If it’s not broke don’t fix
it.” This can be used to describe the ever-changing nitrogen
cycle. When talking about the nitrogen cycle, humans are
now producing additional nitrogen, affecting the normal
nitrogen cycle. The three ways humans are producing
additional nitrogen is through using fertilizers, planting
legumes, and using of fossil fuels [2]. First, planting a lot of
fertilizer has increased nitrogen output. The fertilizer
provides an excellent ground for the microbes I explained
earlier to break up nitrogen molecules and add usable
nitrogen to the environment [2]. Second, planting legumes
such as soybeans and alfalfa also provide a fertile
environment for microbes to live and do the same thing as in
fertilizers. In contrast from natural occurrences to the
nitrogen cycle, lastly, by burning fuel through transportation
and other means, additional usable nitrogen is added to air
and the atmosphere because the air becomes too hot, and that
allows the nitrogen molecules to break apart [2]. These three
ways that humans produce additional nitrogen are a problem
because too much nitrogen is a bad thing. The effects of too
much nitrogen include “worsening of the greenhouse effect,
reducing the protective ozone layer.” [3]
WHAT ENGINEERS CAN DO TO SOLVE
THIS PROBLEM
The biggest thing engineers need to keep in mind
when trying to solve this problem is how to keep the means
of food production the same. With this point said, they
cannot limit the means of fertilizers to a large degree.
Engineers can try to increase the amount of denitrification
being done, but must utilize and make fixed nitrogen
molecules, not dangerous nitrous oxide [2]. Engineers also
are working hard on improving fossil fuels that are
exhausted from cars and other technological items so the
heat does not produce nitrous oxide.
Another thing
engineers are working on is the leaks in the food system.
Fixed nitrogen molecules leak out at points such as from the
feed lot, to the sewage system, and the farms [2]. The
engineers need to find the holes here in the system and fix
them. Finally engineers need to just take care of and recycle
organic waste. Manure and food waste can lead to increased
levels of releasing greenhouse gases [2]. Engineers need to
find ways to control the gases these two things give off and
use them for more beneficial purposes. In conclusion,
engineers can not entirely disrupt fertilizers and the food
cycle. Changing these drastically can raise prices of food
and extend poverty in certain areas [2]. Engineers cannot
make this affect the present with decisions on fixing the
nitrogen cycle for the future. They also though, need to use
ethics when evaluating this problem.
The Dark Side of Nitrogen
Nitrogen clearly has a bad and obvious dark side to
it. When nitrogen breaks apart from its N2 molecules, bad
things can happen. One problem is when nitrogen is
produced during fossil-fuel combustion, it causes severe air
pollution. It also can combine with water, creating nitric
acid in rain. This rain joins with nitrogen from fertilized
fields, farm animal excretion, human sewage, and
leguminous crops. [4] This animal excretion idea and the
nitrogen cycle will be discussed later. Another dark side is
when there is an increased amount of nitrogen in the air,
biodiversity can decline, and there is a greater possibility for
human diseases to occur [4]. Third, a “single nitrogen atom
from a factory, vehicle or farm can acidify soil and
contaminate drinking water before entering rivers where it
can travel to the oceans and help fuel toxic algal blooms and
coastal dead zones.” [4] Lastly bacteria can form into nitrous
oxide at any time along this chain. Nitrous oxide is a
greenhouse gas that can also help deteriorate the ozone layer
[4].
Ethics of Engineering
While it is obviously important in understanding
the actual ways to improve a problem, it is just as important
in understanding the right way to go about it, the engineering
way. This right way that engineers follow when trying to
solve problems, such as the nitrogen cycle, and further
2
Nick DeLuca
building the field of engineering for the future is by abiding
by the code of ethics. There are four areas I focused on in
the code of ethics that I found extremely important in
understanding and further teaching the engineering way. The
areas include: honesty/integrity, promoting the safety and
welfare of the public, accepting criticism and accepting
responsibility for their actions, and finally doing everything
in their power to “enhance the honor, reputation, and
usefulness of the profession.” [6] The code of ethics of all
engineers starts off by saying, “engineers are expected to
exhibit the highest standards of honesty and integrity.” [6]
This statement is probably set forth by many occupations,
but cheaters never win, and a true successful organization
always strives for integrity and honesty. Only solving the
nitrogen cycle in an honest way will be and should be
accepted by the public. Another point made in the code of
ethics is engineers should put at the top of their priority list
“the safety, health, and welfare of the public.” [6] Earlier I
discussed how engineers cannot make decisions that would
drastically impact the food cycle and extend poverty. That
would be a direct violation of the code of ethics and
demonstrates a way in which engineers must look out for the
general public. Third, being responsible for your actions and
accepting criticism is extremely important. [7] This paper
shows that this nitrogen cycle problem will not be easy to
solve. Engineers will fail in attempts to find a solution and
will need to know how to handle adversity. Engineers will
be criticized by the public. Accepting it and being
professional about it is paramount, and handling their
business under state laws stated clearly in the code of ethics
[6]. Engineers should seek criticism and also give it out to
their colleagues. [7] Helping each other out can be a major
step in solving the nitrogen cycle. Lastly, engineers need to
prestige and strive for more competiveness that is needed in
improving the engineering profession [7]. The dedication to
further enhance the engineering profession is a major point
in the code of ethics, and that starts from the bottom, the
freshman year of college in the engineering curriculum.
Then as I started researching my topic, the light bulb in my
head went off. Writing clearly and effectively will make
engineers a better-rounded person [8]. I feel it is important to
research a topic like the nitrogen cycle, or whatever field of
engineering a person may be looking to go into. I was
unaware of what a chemical engineer truly is; now I know at
least one topic that Chemical Engineers study and work at. I
also found out that engineering has a business side to it, and
writing and researching a topic like this helps add to an
engineer’s tool box [8]. I believe other major schools should
have writing assignments like this one in their freshman
curriculum. Students will learn the various problems of the
field of engineering that they may encounter some day in the
real world. At first this project seemed useless to me. I really
had no desire to do this, but as I read over this completed
paper, I realize this was very beneficial to me. Engineers say
writing is possibly one of the most important parts of their
job [8]. I will thank Pitt one day for forcing me to write this
assignment and research a problem in engineering.
CONCLUSION
Engineers have the job of solving problems. They
need to not only solve problems efficiently, but do them the
proper way using the code of ethics. Without the code of
ethics, this profession will not have any rules to abide by.
This paper also clearly describes the major problem in the
nitrogen cycle. Engineers have to identify the problem,
understand the dark sides of nitrogen, and look for effective
ways to solve it while not affecting the lives of people in a
negative way. This problem will impact everyone. I will be
a future engineer and may be attempting to solve this
problem someday with my future colleagues. Hopefully my
colleagues have to do a similar paper like this one. This has
opened my eyes to the real problems in engineering out
there, and also made me realize how truly important writing
is to me as a future engineer. To all the non-engineers, who
will not be tasked with solving and being aware about the
nitrogen cycle, global warming is a big problem. It may not
affect our generation, but future generations down the road
will be affected. We should all be aware of this, and
engineers of the present and future will be working tirelessly
to fix it, the right way.
Writing Papers in Engineering
In deciding what to major in going into college, I
really had no clue what engineering was. The main thing that
I was told was that it was solving problems and to take CHS
physics my senior year. I had an interest in both of those and
decided on engineering. Now that I am here in taking
engineering during my freshman year, ENGR 11 at Pitt
forces us to do writing assignments. At first I thought why
do I have to do these? I chose engineering for a reason.
REFERENCES
3
Nick DeLuca
[1] 2009. "The Nitrogen Cycle." Chemical Business 23, no.
8: 52-56. Business Source Complete, EBSCOhost (accessed
October 6, 2012).
[2] 2009. “Manage the Nitrogen Cycle.” National Academy
for Engineers. Page 1. October 6, 2012.
[3] 2010. The Fondriest Staff. “The Nitrogen Cycle.”
Environmental Monitor. Page 1. October 6, 2012.
[4] 2010. Townsend, Alan R., and Robert W. Howarth.
2010. "FIXING THE GLOBAL Nitrogen Problem."
Scientific American 302, no. 2: 64-71. Business Source
Complete, EBSCOhost (accessed October 6, 2012).
[5] 2011. Julia Haggerty and Hugh Campbell. “Farming and
the environment”. Te Ara - the Encyclopedia of New
Zealand. Page 1. October 6, 2012.
[6] 2012. “NSPE Code of Ethics for Engineers” National
Society of Professional Engineers. Page 1. October 29, 2012.
[7] 2012. “Code of Ethics” American Institute of Chemical
Engineers. Page 1. October 29,2012.
[8] 2012. “Writing for Engineers” American Society of Civil
Engineers. Page 1. October 29,2012.
ACKNOWLEDGMENTS
I would like to thank my roommate Bob Deithorn,
for keeping my sanity and getting through this paper.
I would also like to thank the English Department for
allowing me to find and pursue this topic, as it is part of my
major, and I may be trying to solve this problem someday.
Lastly, my best friend Alex Kajari helped me with problems
along the way from outside sources and kept my attention on
this paper to finish it in an orderly fashion. She is great.
4