I realized that I haven't updated my faithful readers on my dissertation topic quest since April. I've honed in on the terrestrial silica biogeochemical cycle as the topic. Namely, I'm interested in silica deposition, storage, and turnover rates for various soil environments (past and present). With that in mind, here is a new list of possible parts (or chapters) of my dissertation.
1. The effect of sediment mass accumulation rates on phytolith accumulation rates. I’ll compare times of pedogenesis to times of drought. There may actually be more phytoliths entrained in droughty times, due to rapid burial. I've already blogged about this one, and you can see my grant proposal on this subtopic here. Thus, I won't beat a dead horse.
2. Quantify silica (Si) dissolution rates in paleosols. The Si dissolution rate for any soil is pretty easy to calculate: it’s simply the total Si deposition rate (from plant litterfall) minus that which is stored in the soil long-term as phytoliths, and that which is exported out of the soil (by various means). The amount stored in a paleosol is easy to calculate: it is simply the amount present now. The total which was deposited originally is a bit harder to estimate. To do this, I’ll use a modern analog. In other words, I'll try to determine what the conditions were like when the paleosol was formed, and then find an area which has similar conditions today. To determine the modern analogs, I’ll use pollen reconstructions. I’ll need to get two things from the pollen reconstructions: 1) the paleoclimate, which will help me zero in on modern areas with similar climate; and 2) the local vegetation composition. I can also use the phytolith assemblages to determine vegetation composition. This one is important, because species can have differing phytolith production rates. Once the modern analogs are selected, I can use them to measure net primary productivity (NPP) and the phytolith production rate. This only leaves phytolith export to determine, which should be doable as well. Overall, if the dissolution rate can be determined for a paleosol, it should make paleoreconstructions that much more accurate.
3. The effect on soil particle size on Si accumulation/dissolution rates (sand vs. silt vs. clay). There may be more leaching of Si in sandy soils due to higher rates of water infiltration. The dissolution rate may be higher due to this as well. Thus, the Si cycle may be much faster in sandy soils.
4. The effect of soil grain size also has broader implications on the Si turnover rate: does vegetation growing in Si poor soils have a lower phytolith production rate? This one seems kind of obvious, but it may be that most of the Si is simply entrained in the biomass. That which is deposited as litterfall may be quickly recycled back into the biomass. Thus, areas with less overall Si in the terrestrial Si pool (soil, litterfall, and biomass) may have quicker turnover rates.
Saturday, June 30, 2007
My Hectic Schedule
Last night I was relaxing for the first time in many weeks. I got to thinking of all the activities and crises which have occurred in my life since May. Then I got to thinking of all the activities and crises which will occur in my life by September.
Early May
Submitted a manuscript for publication
Wedding planning
Mid May
Final exams, finished term papers
Final phase (frenzied mad dash) of wedding planning
May 19
Wedding
K’s grandpa has a heart attack, but survives. Wedding almost postponed
May 20
Visit grandpa in hospital
Gift opening
Pack for honeymoon
May 21 – 28
Honeymoon in St. Lucia
Early June
Manuscript denied for publication; must revise
Apartment hunting for K
Preparation for field work
June 9 – 10
Kidney stones (fun)
June 11 – 19
Field work in southwest Nebraska, northeast Colorado
My dad is fitted for a pacemaker, but otherwise fine
June 20
Work on lab methods, dissertation proposal
Pack for Minnesota
June 21 – 29
K’s grandpa back in hospital, this time much more serious. Many hours spent in waiting room over many days. He eventually is taken home, and begins physical therapy
Move K with one car and one pickup. This was especially tedious for these reasons:
The move took 12 car/truckloads
Road construction hampered our efforts
Due to K’s grandpa being in the hospital, we really had no time to pack
K must attend Bar classes
June 30
Work on lab methods, dissertation proposal
July
Lab work
Revise manuscript
My dad visits the Mayo for tests on his Pancreatitis recovery. This may or may not involve surgury
Visit Columbia Basin?
August
Move to new apartment
Continue lab work
Continue manuscript revision, if necessary
Visit BWCAW?
Take mini road trip?
Early May
Submitted a manuscript for publication
Wedding planning
Mid May
Final exams, finished term papers
Final phase (frenzied mad dash) of wedding planning
May 19
Wedding
K’s grandpa has a heart attack, but survives. Wedding almost postponed
May 20
Visit grandpa in hospital
Gift opening
Pack for honeymoon
May 21 – 28
Honeymoon in St. Lucia
Early June
Manuscript denied for publication; must revise
Apartment hunting for K
Preparation for field work
June 9 – 10
Kidney stones (fun)
June 11 – 19
Field work in southwest Nebraska, northeast Colorado
My dad is fitted for a pacemaker, but otherwise fine
June 20
Work on lab methods, dissertation proposal
Pack for Minnesota
June 21 – 29
K’s grandpa back in hospital, this time much more serious. Many hours spent in waiting room over many days. He eventually is taken home, and begins physical therapy
Move K with one car and one pickup. This was especially tedious for these reasons:
The move took 12 car/truckloads
Road construction hampered our efforts
Due to K’s grandpa being in the hospital, we really had no time to pack
K must attend Bar classes
June 30
Work on lab methods, dissertation proposal
July
Lab work
Revise manuscript
My dad visits the Mayo for tests on his Pancreatitis recovery. This may or may not involve surgury
Visit Columbia Basin?
August
Move to new apartment
Continue lab work
Continue manuscript revision, if necessary
Visit BWCAW?
Take mini road trip?
Friday, June 29, 2007
Tentative Si extraction methods
I've compiled a list of procedures which I plan to follow in my attempt to more completely understand the phytolith enigma. You can view it here. This is an amalgamation of my own previous phytolith extraction techniques, plus those of other researchers (namely Piperno). Note: this list is tentative, and will probably change...substantially. The notes in italics are areas of experimentation: I'll modify these with some lab time.
Friday, June 22, 2007
Central Great Plains flooding and roadcuts
Check out some of the pictures I took out in western and southwestern Nebraska in early June here.
Friday, June 8, 2007
Perceptions of the anti-liberal agenda
I read this article, and thought you might find it interesting: Bush's War on Whole Foods. It’s about the FTC stopping a merger, which some view as the Bush administration bashing on liberals. I thought the article totally missed the point: the author says there is no harm in two organic grocery chains merging, since they are hardly ever in the same towns. But the FTC says that they can’t merge because it will reduce competition. I think the FTC is right, since there aren’t that many hippy grocery stores out there. If you get rid of the only two organic grocerry chains out there, then you effectively have a monopoly. Sure you can go to Cub Foods and get some organic stuff, but that isn't their main product.
Sunday, June 3, 2007
Which is harder: J.D. or Ph.D.?
Karla recently graduated from law school (PDF here). This is a great occasion, and I'm very happy for her. However, we have an ongoing debate amongst ourselves: which is harder, law school or Ph.D.? What do you think?
St. Lucia plant and animal tour
Check out the PDF I made of the interesting plants and animals of St. Lucia here. This took me a long time to make, so you better flippin' enjoy it!
St. Lucia Volcanics
After receiving an inquiry from T-Bone, I decided to take a closer look at the volcanics of St. Lucia. I put together a PDF file of some images I took while on the island, and you can download it here. I have attempted to speculate as to what created the stratigraphic sequences as best I can; however, I'm not a volcanologist and many of my interpretations are undoubtedly wrong. If anyone has a better interpretation, I'd love to hear it.
Some background information: St. Lucia is located in the Caribbean, at about 13 degrees north latitude. The island is part of the Lesser Antilles island arc, which is itself located on the edge of a subduction zone. The Lesser Antilles are created from volcanoes similar to those found on Japan or in the Cascades mountain range. These volcanoes are highly explosive, with great amounts of volcanic ejecta such as pyroclastic debris and ash (tephra). Known as composite volcanoes, they tend to erupt rarely, but violently. The images in the PDF were all taken on the western edge of St. Lucia, and are in close proximity to the several volcanoes on the island. You'll notice in the images that there seems to be a great deal of volcanic debris along the western edge, which could lead one to believe that the volcanoes of St. Lucia erupt frequently. I cannot attest to the frequency of eruptions on the island; however, I think the last major eruption was in the late 18th century. The large amount of volcanic debris on the western edge is most likely due to the prevailing wind patterns. St. Lucia is located within the Trade Winds, which blow from east to west. This would lead to a greater amount of debris deposition on the western side of the island.
Some of the images show what appears to be tephra layers which fine downward. In other words, thre are rocks and pebbles which are underlain by finer material, probably ash. I have two possible explanations for this. First, erosion may have carried away smaller grains (tephra) at the top of the tephra layer, leaving only the larger pebbles and rocks. Second, almost pure tephra may have been deposited, followed by larger unsorted colluvium from mass wasting. The second scenario may be more likely, as I don't see many cobbles intermixed in the ash layer.
Other images show what appears to be unsorted rocks and boulders mixed into tephra. I would speculate that these are mostly pyroclastic flows, but I may be wrong. They simply may be the result of mass wasting. I would guess pyroclastic flows, as I didn't see any organic material within the strata.
Many of the stratigraphic sequences appear to be loosely cemented, probably due to calcite percolation and precipitation. The loose cementation is a testatment to the young age of these sequences. You'll also note the high angle of repose on these cliffs. This shows that the cliffs are eroding rapidly, which I would guess would be the result of the loose cementation.
Other images show sequences which may have been deposited underwater, and later uplifted. This may be the case, but I am unsure as I didn't see any corals or other macrofossils. My ultimate conclusion is that most of these cliff faces are the result of volcano cone-building (not sure if that's the proper term). Many of these sites are immediately adjacent to old volcanoes, so it seems likely that repeated small eruptions would deposit layer upon layer of debris and ejecta.
There are a couple of images of lava fields in the PDF. A couple things to note here. First, I toured just about the entire western side of the island, but only saw this one lava field; the rest appears to be volcanic ejecta. This is typical of composite volcanoes, which don't produce large amounts of lava. Second, note the strange cleaveage pattern of the lava. These large blocks break apart and fall into the water quite frequently, where they can become hazards for boats. In fact, the locals call this area the "Cemetery", due to a large number of boat accidents here.
Some background information: St. Lucia is located in the Caribbean, at about 13 degrees north latitude. The island is part of the Lesser Antilles island arc, which is itself located on the edge of a subduction zone. The Lesser Antilles are created from volcanoes similar to those found on Japan or in the Cascades mountain range. These volcanoes are highly explosive, with great amounts of volcanic ejecta such as pyroclastic debris and ash (tephra). Known as composite volcanoes, they tend to erupt rarely, but violently. The images in the PDF were all taken on the western edge of St. Lucia, and are in close proximity to the several volcanoes on the island. You'll notice in the images that there seems to be a great deal of volcanic debris along the western edge, which could lead one to believe that the volcanoes of St. Lucia erupt frequently. I cannot attest to the frequency of eruptions on the island; however, I think the last major eruption was in the late 18th century. The large amount of volcanic debris on the western edge is most likely due to the prevailing wind patterns. St. Lucia is located within the Trade Winds, which blow from east to west. This would lead to a greater amount of debris deposition on the western side of the island.
Some of the images show what appears to be tephra layers which fine downward. In other words, thre are rocks and pebbles which are underlain by finer material, probably ash. I have two possible explanations for this. First, erosion may have carried away smaller grains (tephra) at the top of the tephra layer, leaving only the larger pebbles and rocks. Second, almost pure tephra may have been deposited, followed by larger unsorted colluvium from mass wasting. The second scenario may be more likely, as I don't see many cobbles intermixed in the ash layer.
Other images show what appears to be unsorted rocks and boulders mixed into tephra. I would speculate that these are mostly pyroclastic flows, but I may be wrong. They simply may be the result of mass wasting. I would guess pyroclastic flows, as I didn't see any organic material within the strata.
Many of the stratigraphic sequences appear to be loosely cemented, probably due to calcite percolation and precipitation. The loose cementation is a testatment to the young age of these sequences. You'll also note the high angle of repose on these cliffs. This shows that the cliffs are eroding rapidly, which I would guess would be the result of the loose cementation.
Other images show sequences which may have been deposited underwater, and later uplifted. This may be the case, but I am unsure as I didn't see any corals or other macrofossils. My ultimate conclusion is that most of these cliff faces are the result of volcano cone-building (not sure if that's the proper term). Many of these sites are immediately adjacent to old volcanoes, so it seems likely that repeated small eruptions would deposit layer upon layer of debris and ejecta.
There are a couple of images of lava fields in the PDF. A couple things to note here. First, I toured just about the entire western side of the island, but only saw this one lava field; the rest appears to be volcanic ejecta. This is typical of composite volcanoes, which don't produce large amounts of lava. Second, note the strange cleaveage pattern of the lava. These large blocks break apart and fall into the water quite frequently, where they can become hazards for boats. In fact, the locals call this area the "Cemetery", due to a large number of boat accidents here.
Friday, June 1, 2007
A few wedding pictures 1
One of the bridesmaids posted a few pics from the groom's dinner and wedding here.
Would you blog on your honeymoon?
To my devoted blog fans: I apologize for not updating my blog while on the honeymoon. Even though I said I would. I have several reasons (excuses) for not blogging. I've posted some pics here. In honor of Roth's recent graduation, I have decided to make a spin-off of his famous top-ten list. So here it is: Reyersony's top ten resasons for not blogging while on honeymoon. Buckle your seat belts and return your seat backs to the upright position.
10. There was no internet service in the hotel room. In fact, there was only one internet enabled computer at the resort.
9. I only blog when avoiding homework.
8. Even though the resort was all-inclusive, I could not convince the maid to blog for me.
7. I was too inebreated on rum punches (what an awesome drink).
6. My cumulative brain power was focused on the volcanology of the island.
5. My lack of knowledge of tropical phytoliths kept me too depressed to blog.
4. There are no cartographers on Saint Lucia to make fun of.
3. There are no critical geographers on Saint Lucia to make fun of.
2. I was too busy sweating from the heat.
1. I was on my honeymoon. I had husbandly duties to attend to.
10. There was no internet service in the hotel room. In fact, there was only one internet enabled computer at the resort.
9. I only blog when avoiding homework.
8. Even though the resort was all-inclusive, I could not convince the maid to blog for me.
7. I was too inebreated on rum punches (what an awesome drink).
6. My cumulative brain power was focused on the volcanology of the island.
5. My lack of knowledge of tropical phytoliths kept me too depressed to blog.
4. There are no cartographers on Saint Lucia to make fun of.
3. There are no critical geographers on Saint Lucia to make fun of.
2. I was too busy sweating from the heat.
1. I was on my honeymoon. I had husbandly duties to attend to.
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