Feeds:
Posts
Comments

(Wrote this in December as a environmental writing sample)

 

The EPA To Regulate Asbestos and Other Toxic Chemicals

 

The EPA has released a list of ten chemicals to be regulated under a new amendment to the Toxic Substances Control Act.

 

By Glenn Nelson

 

On June 22, 2016, President Obama signed the Frank R. Lautenberg Chemical Safety for the 21st Century Act into law. The new law amends the Toxic Substances Control Act (TSCA), and will require the EPA to evaluate existing chemicals with “clear and enforceable deadlines,” according to an agency press release. The law aims for “increased public transparency,” while holding the chemicals to “new risk-based safety standards.”

On November 29, the EPA released a statement listing the first ten chemicals to be evaluated under the new law. These chemicals include asbestos, dioxane, and carbon tetrachloride, amongst other common chemicals.

Asbestos is perhaps the most commonly known chemical on the list and has already been classified as a known carcinogen by the U.S. Department of Health and Human Services. Asbestos is associated with mesothelioma, lung cancer and other health problems. According to the National Institute of Health, disturbing asbestos products can release fibers into the air, which can become trapped in the lungs for long durations.

In the past asbestos was commonly used by the building industry for insulation, fireproofing, roofing and sound absorption. In 1989 the EPA banned all new uses of asbestos, however uses predating the ban were not regulated. Despite there being no effective ban on asbestos, there has been a significant decline in consumer use.

The EPA chose the first ten chemicals from a list of 90. The chemicals were selected for evaluation on the basis of potential hazard, and the likelihood of public exposure. The EPA will be choosing additional chemicals to evaluate and must have 20 chemical risk evaluations ongoing by 2019. At least half of the chemicals evaluated by the EPA must come from the TSCA Work Plan, until the list of 90 chemicals has been exhausted.

 

 

Works Cited:

 

https://www.epa.gov/laws-regulations/summary-toxic-substances-control-act

 

https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/evaluating-risk-existing-chemicals-under-tsca#chemical%20selection

 

https://www.epa.gov/newsreleases/epa-names-first-chemicals-review-under-new-tsca-legislation

 

https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/frank-r-lautenberg-chemical-safety-21st-century-act

 

https://www.epa.gov/chemicals-under-tsca

 

https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/asbestos/asbestos-fact-sheet

 

 

 

 

fullsizerender

For the past six months I have been working on a “sustainable,” organic sugar bush. In that time I have seen a number of impacts, which seem like a necessary consequence of our activities, that certainly appear to impact the landscape. However, the industry maintains that when tapping is done right, the impact to the trees should be negligible and the woods should be preserved. In fact, one of the aspects my company brags about, is that the woods have been preserved from logging and development. While clearing the woods for logging or development may be more obviously impactful, there are still aspects of the process which should be more deeply investigated before we can call the industry sustainable.

 

The first (and probably most noticeable) impact which should be examined is the use of plastic piping to convey the sap down the mountain. Best practices suggest that the 5/16″ lateral lines be replaced every five years, drop lines every three to five years and one inch branches every ten to fifteen years. The plastic can sometimes be melted down and reused, but it is uncommon to see recycling of these materials on a large scale as of yet. Considering that we’ve used tens of thousands of feet of one inch piping and possibly hundreds of thousands of feet of 5/16″ lateral line, we are certainly creating untold tons of plastic waste, every few years. The University of Vermont claims that as many as 88 tons of maple tubing are replaced in the Vermont woods, per year, as of 2009. This number is surely higher by now, given that there are many more large producers taking up residence in the state. UVM then predicted that sugarmakers would make progress in recycling in the years to follow, and they have, but to what degree is not yet clear, and there is certainly still a large amount of waste being produced.

 

Waste is not the only question raised, when we consider sustainability in this industry. There is also the question of tree health. The industry claims that when tapped properly, sugaring should have no negative impact to the health of the tree, or at least negligible impact. Producers have been using smaller tap sizes to reduce the amount of dead transport wood created in the tree, but they have also started using vacuum systems to create a pressure differential, tricking trees into thinking their is higher atmospheric pressure, and thus that it is an appropriate time for sap to run. The impacts of vacuum are still an open question, as far as how trees are impacted. On a basic level, the vacuum has allowed syrup producers to collect more sap per tap. This alone should be a red flag. Trees use the sap we wish to collect to build new structures each spring. This includes the leaves needed to photosynthesize and reproductive organs. The greater the sap we succeed in pulling from the tree, the less it has for itself. While research done by UVM would suggest that there are no known impacts, it seems obvious that there must be at least some detrimental effects, and that perhaps we just aren’t seeing them yet.

 

Furthermore, there is the open question as to whether the scarring is expanded by draining more of the tree’s transport wood. In experiments conducted by UVM, the trees subjected vacuum did not show statistically significant impacts, compared to those tapped with gravity. I would consider the results of the 2007 study to be inconclusive and requiring further investigation. I would hypothesize that trees subjected to multiple years of 25″ Hg of vacuum would show advanced scarring, compared to gravity taps of the same size, but there is no available data yet.

 

Finally, sugar bushes fragment habitat, in woodlands considered by the companies tapping maple trees to be “conserved.” The larger the sugarbush, the more infrastructure and development is necessary to get the sap out. First roads are needed to make the installation possible. Second, branches are often cleared of brush to make the installation of one inch pipe and main lines easier. The installation of tubing further fragments the woods. Many involved in the installation of sugaring infrastructure anecdotally claim the impacts on wildlife to be negligible, but this seems highly unlikely. The use of noisy machinery like chainsaws and ATVs disturb wildlife and often chase them from the immediate area. The infrastructure installation fragments the areas where animals need contiguous habitat to range.

 

Study has been done on how sugarbush management compares with biodiversity management standards. However, there seems to be an open research question in verifying whether the practices in use are, in fact, impacting habitat. Simply using observed control species-area relationships vs. experimental species area relationships on sugarbushes could help to answer this question.

 

While the industry continues to claim it is operating in an environmentally sustainable manner, I feel there are many open research questions that need to be resolved before we can use the term sustainable. My hope is that research institutions like UVM will continue to investigate these questions, and that best practices can be improved within the industry. It will take cooperation between the private industry, research institution and governmental regulatory agencies to advance the cause of sustainability.

I generally abstain from political writing in this context, but as this past election has so many implications for scientific research, especially as it concerns ecological issues, I feel it is important to say a few things. This evening I wrote the following letter to the editor of the New York Times:

 

 

In recent days, the blame has already begun to circulate concerning the clownish travesty that is the election of a racist pervert to the highest office. Is James Comey to blame for his remarks regarding the Clinton email investigation, or perhaps the votes could have been found in some third party candidate’s tally (perhaps in the 11,000 that voted for a deceased gorilla). The truth is the DNC and Hillary herself bear most of the responsibility. The democrats, by running a lackluster candidate (see John Kerry in 2004), with a long list of past indiscretions, failed to present the type of vision that the Obama coalition so strongly responded to. In the end, her own  disingenuous reputation and a Regan Democrat’s policy platform, ensured that only those who strongly feared four years of rabid nationalism would “hold their nose” for her. I only hope that this is a wake up call to the whole party going forward. We want genuine progressives.
The subtext to this letter may not immediately be apparent, and this seems an appropriate place to expound upon what was truly at stake, and how the Clinton campaign missed that.
I have, too many times to count, criticized secretary Clinton for not being a true progressive. Her support of foreign wars has led to neoconservative endorsements, something that should trouble anyone who, like me, came of age under George W. Bush. Her economic policies seemed too centrist, and even those policies may have been to the left of her actual stance (exhibited by her Wall Street speech leaked by wikileaks). However, none of these issues troubles me more about her, and the Democratic Party in general, so much as the failure to acknowledge the greatest challenge of our time… Ecological Overshoot.
The concept of ecological overshoot was first popularized by the Club of Rome’s book Limits of Growth. This book, first published in 1972 and then updated every ten years since, used computer models to show how human population would continue to grow until it overshot the ecological carrying capacity of the earth. The models predicted a disastrous crash prior to the year 2100, which would, for perhaps a millennia, negatively impact the resources which are necessary for human survival. The book highlights three necessary conditions for overshoot: 1. Accelerating Growth, 2. Limit or Barrier to sustained growth (i.e. finite resources), and 3. Delayed Response to the impending crisis.
Overshoot is often perceived in economic crises, such as the housing bubble. Growth in the market continued past the point of sustainability. Loans were given to increasingly unqualified borrowers to artificially inflate demand, and this continued long after evidence of the problem was perceptible.
Recent developments in ecology should illustrate that we indeed have an impending problem. First, temperatures are rising from excessive CO2 consumption, causing climate disturbances such as large scale droughts, super storms, polar ice melt etc. Second, wildlife has shown signs of massive decline, on the scale of a mass extinction (30% of North American Birds are in Decline, the world’s wildlife populations have decline by 50% in 40 years). Third, pollution is causing ecosystem declines (see ocean acidification). Finally, we are experiencing shortages of water and food within the human economic system. These are all symptoms of the main problem… The mythology of sustained growth.
Certainly one candidate was worse than the other on these issues. The perverted clown that has inherited the privilege to serve as Commander in Chief has called Climate Change a hoax and expressed broad skepticism about environmental science. However, Clinton failed to significantly differentiate herself from his agenda, and failed abjectly to identify the problem. Hillary Clinton did as all politicians in America have done before her, she has called for economic growth to solve the problems of the world. This was the Regan answer, and the Democrats have come to embody that agenda, rather than present an opposing vision.
Climate Change, given the growth model our political system espouses as the treatment of economic ills, is the elephant in the room. No Democrat, Clinton especially, has succeeded in presenting a vision for sustainable economic development based on system equilibrium. It has become apparent that wild fluctuations are required in a growth model, while equilibrium models are more resilient to disturbances (see an old growth forest). That is not to say equilibrium are completely stable, they aren’t. They are dynamic, but as mentioned resilient. That resiliency is precisely what the nation needs. Wealth disparity is out of control, and when disturbances hit they effect those of us at the bottom harder and for a longer period of time. There are those still suffering nearly ten years after the start of the great recession and six years after it was declared over.
An economy should be able to recognize a stable state and seek to elongate it. Instead, our system seeks to outdo itself each year, quickening the pace of destruction and depletion at an exponential rate. However, if population stabilized, food systems could stabilize and resource consumption and pollution could stabilize. With growth you take the good with the bad, and we’ve been led to believe, erroneously, that that is preferable.
Clinton tried to stick to an old playbook, one that is obsolete, one that no longer brings millennial out to the voting booths. If the Democrats wish to perform better in the future, they will have to analyze the old laissez faire capitalism model, and start looking toward sustainability. They are dealing with a youth vote that is increasingly aware of their ecological impacts, and wish to make a real, positive change. If the Democratic Party wishes to go forward it will have to retire its bench candidates in favor of those with progressive visions. People no longer want to “hold their nose” for the “lesser of two evils.” The lesser evil is still evil.

img_1449

 

 

 

Trees are a source of fascination, largely because of the length of their individual lifespan, and their impressive size. They are living things that seem almost inert, because of the long time scale through which their reactions occur. We often regard trees as more of a community than a population, because they rarely exist in pure stands… The more we come to understand about trees, the more this seems the correct approach.

 

Recent discoveries about the relationships between trees and soil fungi have opened some new and very fascinating philosophical questions about how to define an organism and what constitutes intelligence.

 

The cell, as should be common knowledge, is the smallest unit of life–meaning that it is the smallest thing that carries out all the functions we define as biotic functions (i.e. growth, response to stimuli, reproduction, etc). Cells make up networks that function together known as organs, and organs function together as organisms… This is just the beginning of telescopic categories in the organization of life.

 

One of the systems in our own bodies in which cells function together is the nervous system. Our nerves receive a stimulus, that is transmitted by electrical signals to our brain. The brain then decides to respond and this is transmitted back to the part of the body that received the stimulus.

 

The more we come to understand the relationship between trees, the more forests begin to resemble vast networks of nerves in an organism. Trees receive a stimulus, from an insect pest for instance, and they send a chemical message down to their roots. Attached to tree roots are tiny fibrous fungi, that transfer these chemical signals between trees. The trees can than produce tannins to give their leaves a foul taste and prevent insect damage.

 

The mycorrhizal fungi play an important role as a sort of nutrient exchange economy in terrestrial ecosystems. The tree transfers sugars made during the photosynthesis process, and the fungi transfer minerals and nutrients from the soil, namely phosphorus and nitrogen. The fungi gain these nutrients by decomposing living things in the soil. In times of normal growth, there is an exchange, but in times of stress, the tree can regain sugars it loaned to the fungi. They can also transfer from one tree to another tree, and this is the method by which chemical signals are sent.

 

Trees do not just transfer nutrients between others of the same species. As Suzanne Simard discovered, birch and Douglas fir transfer carbon back and forth through mycorrhizal fungi, with older trees often helping younger trees, more often than not of different species. This mutualistic relationship questions the Darwinian supposition that different species are in constant competition for resources (though mutualism has long been known in nature, and does not challenge evolution). However, this does suggest that forests are perhaps macro organisms, with the various parts (trees and fungi) functioning for the survival of the whole.

 

This is further supported by Simard’s work, which suggests that trees generally allocate their resources to trees more likely to survive in current conditions. For instance, spruce trees passed nutrients to Ponderosa pines (a tree more resilient to climate change), even when young spruces were present). This suggests that, not only are trees cooperating between species, but they may be doing so intelligently.

 

This is a body of research that is far from established, but many of the results are shedding light on aspects of ecology that many could not have before imagined. It is changing, slowly as a tree’s time scale, the belief that trees, or better, forests are passive and unintelligent.

 

Certainly, the idea that trees or forests possess intelligence, self-awareness, consciousness, is a controversial, but not impossible idea. Just because trees do not react in a time frame people can easily observe, does not mean that they do not possess some sort of intelligence… But how, if not through a brain? How do we understand the anatomy of a forest? How do we measure its intelligence? These are all questions for future research.

 
Citations:
http://www.waldwissen.net/wald/baeume_waldpflanzen/oekologie/wsl_mykorrhiza_lebensgemeinschaft/index_EN
https://www.boundless.com/biology/textbooks/boundless-biology-textbook/soil-and-plant-nutrition-31/nutritional-adaptations-of-plants-188/mycorrhizae-the-symbiotic-relationship-between-fungi-and-roots-716-11940/
http://www.bbc.com/earth/story/20141111-plants-have-a-hidden-internet

FullSizeRender

As I hiked Haystack Mountain in Pawlet, Vermont yesterday, I was impressed with the amount of diversity preserved in just a small tract of land. The North Pawlet Hills Natural Area preserves a little over 1,000 acres, yet from the trail it is possible to observe a strikingly large number of distinct habitats. Part of this is undoubtedly because the elevation changes so drastically, but it is also noteworthy that the Nature Conservancy intentionally focused on the preservation of land of high conservation value.

The conservation movement, over the years, has made strides in putting high value lands in the public trust, but it has also been a strategy with limits. This is why land trusts are so valuable. Land trusts can step in to conserve parcels  when there is not the political will to conserve the land in the public parks systems available.

When the government protects land, it protects lands that are valuable for recreation or for natural resources. Ecology is more often than not a secondary concern. The Forest Service manages forest resources for what it deems to be a sustainable timber harvest. In other words, a rate of timbering that does not degrade the forest in the long term. This is a useful strategy, seeing as we live in a society dependent on forest products. The Parks Service, on the other hand, manages lands for the recreational experience of National Park visitors. In the case of many of our previously wild parks, this has meant developing the kind of infrastructure that can handle the ever increasing (and under-educated in regards to leave-no-trace principles) visitorship. In both cases, governments have an anthropocentric management style, and this has resulted in a long term degradation of the resource, (barring the occasional, but rare wilderness area, where greater restrictions exist).

Even this anthropocentric management style has dried up in recent years. As budgets have become tighter, political will for conserving land has all but evaporated. This all during a time when the scientific community has raised concerns about biodiversity loss, due often to habitat fragmentation. As more land becomes developed for human interests, and the government fails to push back, land conservation has been left in a vacuum.

Fortunately, many non-profit land trusts have cropped up, in order to nickel and dime properties deemed to be of high conservation value, but often too small, or too lacking in recreational opportunities, to be of public interest. Often times, the trust will buy a tract in fee simple (meaning full ownership), but more often land trusts utilize scenic and conservation easements that spell out rights, restrictions and responsibilities of both the property owner as well as the land trust. Land trusts monitor the properties periodically to ensure the terms of the easement are met. Easements are backed by law, and there are legal ramifications for violating the agreed upon terms, however they are entered into voluntarily by private landowners interested in preserving  their property for future generations.

This is not a great strategy for large land acquisitions, but it has worked, piece-meal, to make additions to conserved lands, or fill in the gaps that the government is not willing to. For instance, in the Essex Chain of Lakes acquisition, in the Adirondacks State Park in New York State, it was uncertain whether the Department of Environmental Conservation would have the resources necessary to take over the property, which had previously been held by the timber company Finch Prine. As it became clear that the paper company wanted out, the Nature Conservancy acquired the parcel in fee and then sold it at a discount to the State of New York for admittance into the Adirondack Park. This process took years, but the Nature Conservancy was able to identify a parcel with high conservation value, and protect it.

Haystack, similarly is a property with high conservation value. As one walks up the mountain, you start in a typical example of Northern Hardwoood Forest, along rolling terrain that varies from wet to mesic, and often consists of Rich Northern Hardwood forest matrix communities. These communities are dominated by Sugar Maple, Beech and Yellow Birch. There is one point in the beginning of the trail, where a wetland is visible, though it is unclear whether it is a bog, fen or swamp (from the trail). However, with wetlands being home to immense biodiversity, being providers of essential ecosystem services, and being highly productive ecosystems, it is clear the area is of high ecological value.

Through the lower forest, one can hear an incredible diversity of bird life. From canopy birds like the blue-headed vireo to the elusive hermit thrush, it is well worth stopping to take the varied calls in.

There is also great diversity in the understory, from the common witch hopple, blue cohosh, jack-in-the-pulpit, blue-bead lily, red trillium, cranesbill and various ferns, to the poisonous nightshade.

As the elevation picks up, the change from wet northern hardwod foorest to mesic oak habitat becomes clear. The southern exposure is dominated by northern red oak and white pine, as well as a wide array of understory shrubs and plants. The herbaceous layer, once dominated by jack-in-the-pulpit and blue-bead lily, and blue nightshade, is now taken over by foam flower and witch hopple. As the elevation rises, the understory becomes thinner and there are more hemlocks, though the dry southern exposures still contain oaks.

IMG_0992

White oak trunk, surrounded by maple leaves.

At the summit, there is almost an alpine meadow. Here there is only a stunted canopy of Northern Red Oak. Here and there there are speckled alders, but mostly there is an abundance of alpine bilberry, three-toothed cinquefoil and pale corydalis. There area few sedges lining the rocky escarpments, but the soil is very thin and dry at the peaks.

IMG_1001

pale corydalis

IMG_0988

View from  the summit of Haystack, Mt, Pawlet, Vt.

Just in the course of an hour, the trail traverses this entire diversity.

It is clear that the Nature Conservancy considered recreational value to the community in preserving the North Pawlet Hills property. However, the biodiversity preserved on the property is extensive, and provides an oasis of habitat for species that might otherwise be threatened by fragmentation, caused by extensive farming in the region. For its size, the preserve accomplishes a lot of positive goals.

 

There can often be public confusion at the decision of a land trust to preserve properties with low recreational value, as is the case with the Natural Lands Trust’s preservation of wetlands in western New Jersey. However, when you consider that the protected worm-eating warbler utilizes this habitat for nesting, and the wetlands are home to plants that are rare and endangered in the state, it becomes clear that the land has high conservation value. However organizations like the New York-New Jersey Trail Conference have been clamoring for more access and the right to build extensive trail improvements for the Highlands Trail through these habitats. Many in the hiking community cannot see why there is resistance from the land trust. However, this lays bare the argument in favor of protecting lands through the use of land trusts. The mission of the Natural Lands Trust is to preserve biodiversity, not improve recreational opportunities or garner public interest. Thus, land trusts such as this have the ability to resist public pressure, in order to do the right thing ecologically.

 

The benefits of land trusts are many. While sometimes those benefits align with public interest, often times they are able to take a longer view, for the purpose of serving the greater good. As the will to preserve large tracts of land continues to dissipate, it will become increasingly important to ensure the resources are available to protect the smaller habitat corridors, that enable extensive ecosystems like the north woods to function.

In recent years, it has been court ordered that new structures and trails built on federally protected land must accommodate the Americans with Disabilities Act. The idea of this certain comes from the well meaning idea that people with disabilities have a right to access all the places that individuals without disabilities can access. In principle I understand this idea, but in practicality and ecologically, this ends up being that well known road to hell, paved with best intentions.

ADA structures and trails are considerably larger and more expensive to build. But to use this logic alone would be a contradiction of my principles that environmental regulation should be implemented without regard for economic costs, since it involves the greater good for both human and non-human life. However, there is a point to be made, that by enlarging these structures, we are bankrupting the agencies and non-profits tasked with their building and upkeep. This is a very real problem, when you consider that the National Parks Service already has a multi-billion dollar maintenance backlog. So, you have to consider that, with agency charged with the stewardship of natural places, there is now an opportunity cost between doing the good work they were originally tasked with, i.e. ensuring we continue to have natural wonders worth appreciating, and providing for the onerous stipulations of the ADA requirements.

 

More than just dollars and cents, there is also the issue of its impracticality. For trail spec, ADA requires that treads be hardened with a specific type of well compacted gravel (not available easily in wilderness areas, where the wilderness act requires no motors be used) and that the grade not exceed (if I remember correctly) 3% (a task near impossible on rocky outcrops, or in the beaver inhabited north woods).

 

Furthermore, the ecological footprint of ADA structures and trails is much greater than those built for sustainability. Wilderness trails have gone through much evaluation as to how to use available materials to minimize erosion and to concentrate traffic through sensitive areas. ADA trails are much wider and require materials that are just plain unavailable in backcountry sites. The require, also, a greater degree of site disturbance, both because of the logistics of getting materials to the site, and because of the higher engineering standards. If we made every new trail construction project to meet ADA requirements, it’s unlikely many would make it through the NEPA process, and truthfully they shouldn’t.

 

There are someplace where people should not go, for the betterment of highly sensitive ecosystems. Take alpine zones for instance. Which have a high occurrence of plants which are endangered and delicate. No foot traffic whatsoever should be allowed on areas where that foot traffic may disturb the last of a species. There are degrees of delicacy however, and some sensitive areas can manage light foot traffic. Take rich northern hardwood forest. There are a great many species that only grow in this limited habitat, because of the high level of resource availability. A small degree of foot traffic minimally disturbs a limited area, but allows the vast majority of the habitat to survive. This habitat, if paved over and altered to accommodate a 3% grade, would not allow for the integrity of unfragmented habitat.

 

Ecologists have learned more and more how ecosystems function as a whole system… That many organisms require sizable unbroken area to thrive. Studies have elucidated how even foot traffic can disturb the distribution of organisms. Surely, if we build easily accessible paths through sensitive habitat, we are inviting a degree of human disturbance that could alter and limit the capacity of many systems.

 

That the ADA has been ruled to supersede even the Wilderness Act has been much to the detriment of natural resources and the organizations tasked with the management of those areas. While disabled people should be accommodated where possible, we need to recognize that there are certain things that are inaccessible to certain people. Wild places should be that, wild, and man should only be a visiter to the wilderness. When we pave over it to accommodate recreation, we are saying that we no longer value protecting places from the negative influence of human presence. The loss of wildness in our wild places would truly be a much greater tragedy than the idea that their beauty is not accessible to all. We must acknowledge this, because their beauty is not for us to begin with, but for the sake of its own mysterious function. Ecosystems are unaware of beauty. They exist because of millions of years of evolution, selecting perfectly for the exact conditions necessary for survival. Our presence in such places is unnecessary and accidental, and should remain so, to allow such places to exist that are not influenced by the hand of man.

INTRODUCTION:

The effects of extreme pH are known to effect enzymatic function in organisms. Extremes on either end of the pH scale can denature enzyme proteins and impede function. The goal of this experiment was to test whether pH extremes, (of 2 on the acidic side and 10 on the alkaline side), would register a discernable effect on enzyme function during fermentation.

To understand how to measure enzyme function, it is first necessary to understand how fermentation works. Fermentation is an anaerobic process, in that oxygen is not necessary during the process. Following glycolysis, pyruvate remains to be metabolized, which in an aerobic environment happens through the citric acid cycle. Lacking oxygen, pyruvate can either be converted into alcohol using alcoholic fermentation or lactate through lactic acid fermentation. During alcoholic fermentation, NADH and ATP created during glycolysis is broken down to NAD+ and ADP and inorganic phosphate to be reused in glycolysis. Also released is ethanol and carbon dioxide. The output of alcohol and CO2 are the best methods for measuring fermentation productivity. (http://www.nature.com/scitable/topicpage/yeast-fermentation-and-the-making-of-beer-14372813).

There is a good deal of experimental evidence that suggests yeast productivity is optimized in a pH environment of about 5. Many of the studies focused on the medium acidity range of 5.5 to 4, and not environments of extreme acidity. Furthermore, most of the available research focused on ethanol output, likely for its usefulness in aiding brewers of alcoholic beverages. (https://www.researchgate.net/publication/233755737_Factors_affecting_ethanol_fermentation_using_Saccharomyces_cerevisiae_BY4742, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1087585/, http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.1988.tb04312.x/full).

For our experiment we are particularly interested in the output of carbon dioxide as a result of exposure to extreme pH. Typically, when concerning enzyme function, it would be reasonable to hypothesize that extremes in pH will lead to the denaturing of enzymatic proteins, reducing their ability to function and thus their output. However, since carbonic acid results from CO2 released in fermentation reacting with water, it is possible that the carbon acid would neutralize the basic solution, reduce the pH of the control and buffer the more acidic solution back toward neutrality. If this is the case, the extremes could function with relative normality, in relation to the neutral solution. (http://ion.chem.usu.edu/~sbialkow/Classes/3650/Carbonate/Carbonic%20Acid.html).

 

METHODOLOGY:

The experiment was conducted by making three 9ml solutions (9ml being constant). The independent variable being pH, the control group lacks a pH buffered solution, but contains distilled water (6ml), corn syrup – diluted to 50% (1ml) and a yeast suspension (2ml). The alkaline solution consists of no distilled water, corn syrup (1ml), yeast suspension (2ml) and a buffer solution with a pH of 10 (6ml). The acidic solution was made with no distilled water, corn syrup (1ml), yeast suspension (2ml) and a buffer solution with a pH of 2 (6ml).

The three solutions were added to test tubes labeled “control,” “tube 1” (pH 10), and “tube 2” (pH 2). The test tubes were sealed with a rubber stopper with tubing leading to a second test tube filled with water and placed upside down under water in a beaker. The starting air pocket in the test tube was marked with a wax crayon on each of the test tubes, and each tube was marked again at 5 minute intervals (another constant). The experiments were placed in a water bath of 45 degrees Celsius, to keep temperature constant during the experiment’s duration. Finally, following the experiment, each group was tested with a pH buffer strip, to see whether the solutions had changed pH over time.

 

Materials:

6 – test tubes

3 – rubber stoppers with tubing

3 – beakers

5 – pipettes

1 – metric ruler

1 – wax pencil

3 – pH buffer strips

6 ml – distilled water

3 ml – corn syrup (1 ml for each group)

6 ml – yeast suspension (2ml for each group)

6 ml – pH 10 buffer solution

6 ml – pH 2 buffer solution

 

RESULTS:

The results of our experiment did not entirely confirm our initial hypothesis. We intended to run our experiment for 30 minutes, but only made it to 10 minutes with 2 of the 3 groups. The control group performed best, with tube 2 (pH 2) achieving similar results, while tube 1 (pH 10) performed poorly. With the control group, the air had been displaced by 38mm after five minutes and 110mm after ten minutes. The 15 minute mark was not reached, as the size of the test tube was exhausted. Tube 1 (pH 10) reached only 8mm after five minutes and 10mm by ten minutes and remained at that level at fifteen minutes. Tube 2 (pH 2) reached 40mm by five minutes and 74mm by ten minutes, and had also exhausted the size of the test tube by the fifteen minute mark.

The starting pH for the control was 7 and had departed to 4 by the end of the experiment. The starting pH for tube 1 was 10 and had departed to 8. Finally the pH for tube 2 started at 2 and ended at 4. This shows that for the lower pH range our hypothesis was largely confirmed, but was only partially confirmed for the alkaline group.

 

Table 1

Test Tube # 0 min 5 min 10 min 15 min
Tube 1 0 38 110
Tube 2 0 8 10 10
Tube 3 0 40 74

 

 

Fig. 1

Yeast figure

CONCLUSION:

Both high and low pH extremes tend to denature enzyme proteins, reducing their ability to function. Thus it would logically follow that our results should mirror this. However the internal chemistry of organisms often have mechanisms for buffering high and low pH to maintain equilibrium. This experiment exhibited both this capacity for buffering, as well as the limitations. As was seen in the alkaline experimental group in test tube 1, the solution of pH 10 buffered to 8 neutral, but failed to make it all the way before function ceased. This is still impressive because the final result was a solution with a pH 100 times less basic. In the case of the acidic experimental group in test tube 2, the pH buffered back to a pH of 4, or 100 times less acidic than the original solution. Both solutions were able to use carbonic acid to neutralize, but enzymatic function was considerably better in an acidic solution.

The original hypothesis stated that both solutions would be able to buffer enough toward neutral to function with relative normalcy. This assumed that yeast enzymes functioned optimally at a neutral pH, and that tolerable departure from neutral would be the same in both directions. Through research it was discovered the yeast function better in mildly acidic environments and through experimentation it was show that yeast toleration to acidity is much higher than its toleration of alkalinity. The original assumptions were not verified by this experiment, and future experiments would be useful to determine what degree of acidity is tolerable to yeast enzyme function.

This experiment, while able to offer valuable information feel short in some important regards. Mainly, the test tube size proved too small to appreciably handle the amount of CO2, and limited the length of time the experiment could be conducted. This also limited the results to only 2 data points instead of 6. More data would have given a higher degree of confidence in the results. That said, the experiment was not inconclusive and did offer useful information.