SUCCESS!
Here's a "quick post" to bring you all up to date with the basic results of yesterday's continuation of the drilling and sampling. We completed our quest for the bottom of the Pond's basin with the aid of Russ Lanoie's expertly designed and fabricated tripod/come-along retrieval system, his small Yanmar tractor and trailer, and the able assistance of the project's staff and several volunteers. I will be posting another "Thank You" in the next day or so to recognize each of these folks and their specific contributions. But for now, many thanks to everyone!!
We were able to reach a total and final depth of approximately 33 feet beneath the Pond's bottom or approximately 79 feet beneath the water surface of the Pond. These depths will be more specifically defined after we reduce the field data taken during the driving and retrieval process for each sample. Meantime, the precise GPS information for the hole location is: Latitude 43-56-29.7678; Longitude 71-07-5.2484; and elevation 647 feet above sea level.
Sample recovery from the two days of work (3/11 & 3/17) includes approximately 30 feet of greenish brown to dark brown, lightly to moderately compacted gyttja (organic pond muck, as described in earlier posts) and approximately 3 feet of gray to light gray, moderately to well-compacted, glacially derived clayey silt. The gyttja sample just above the clayey silt seems (preliminarily) to show a gradual transition from cold immediate post-glacial conditions to gradually warmer conditions in the Pond's local area as glacial ice receded away from the area - just what we were hoping to find.
We did not find the absolute "hard bottom" of the Pond's basin (e.g. bedrock or in-place glacial till) because of the difficulty we finally had in driving the sampler into the substantially compact post-glacial sediments. However, the presence of these sediments and the nature of their compaction suggests we stopped drilling and sampling close to their base and thus the bottom of the Pond's basin.
The exact nature of these sampled materials and the specific circumstances of the transitions they reveal has to await the results of the laboratory work that will start after the next step in our process. That is for the project staff to get together to split, carefully describe/photograph, and extract specific samples for lab testing from the cores retrieved. Due to pre-existing professional and business commitments of project staff (ugh), this activity is scheduled to take place in early May over at the cold walk-in storage facility at Plymouth State University. Thereafter, and as the results of the various lab tests (C-14, pollen, chironomids, etc.) come in, we will begin to fill-out the details of the Pond's geologic, biologic, and climate history - probably by the mid to late summer.
So, the first and most logistically challenging step in the project is complete. Now on to the really interesting stuff. Stay tuned here on the blog. We'll keep you posted.
4 comments:
Congrats on a successful day! Looking forward to pics of the rig! I suspect Bob Denoncourt may want the tripod and comealong to haul those big trout and pickerel he catches out of the water! ... Bob
You have to picture a whole group of supposed adults whooping for joy as light gray (i.e., glacial) and not just dark brown (i.e., organic)muck came extruding from the corer after the last and deepest thrust! Most of us haven't done that since we were 6 years old anticipating a session with mud pies!
Lee
it has been fun to see your progress. we have even wished we might be there with you ( for a few hours.)
i have a question about the BPPP map of the fish and game dept. They classify our pond as oligotrophic! the definition i look up ( lacking nutrients, having large amounts of dissolved oxygen ) doesnt sound that good for us, but maybe i am misunderstanding. Perhaps the lack of nutrients means low plant life which is really good. So which is it, good or bad?
thanks for you great work.
dick
Hi Dick
No, oligotrophic is what we want to be. All lakes go through an evolutionary process in time. They may start life, for example, after glacial scouring and then its retreat, as rocky basins containing little bottom sediment and filled with pure meltwater that has very few nutrients in it. These conditions make it tough for phytoplankton (i.e., algae) to grow very robustly – plenty of light but few nutrients. But they do increase some, but then they die and slowly sink to the bottom where, over months, they decompose and break down, releasing back to the overlying water the nutrients they did manage to capture and incorporate into their bodies. The next year, as winds cause the water in the lake to mix top to bottom, these nutrients are returned to surface waters where the sunlight is present, providing that year's phytoplankton with the two ingredients they require - light and nutrients. But in addition to getting back those recycled nutrients, there is an influx of more nutrients rinsed into the lake from erosion in the surrounding watershed. So this year there are more nutrients than last year, and the phytoplankton can grow more and be more productive. And so it goes, year after year, adding this year's new watershed rinsings to last years recycled nutrients, incrementally building up nutrient levels and stimulating more and more phytoplankton growth and productivity. The process is called "eutrophication" and it starts in a "few-nutrients" or oligotrophic circumstance, but then builds to lots of nutrients = eutrophic conditions. It's a natural process over time. The rate at which nutrient build-up, and thus plankton productivity, depends on the chemicals available in the surrounding watershed (esp. phosphorus, nitrogen, potassium, iron, and others key nutrients that plants require) and how easily these nutrients can be eroded from the rocks and rinsed downhill into the lake.
Now enter humans and their excess fertilizers and sewage wastes - all of which are rich fertilizer sources of N, P, K, Fe etc. Adding these to the natural nutrient enrichment described above can easily accelerate the nutrient buildup process and overwhelm the ability of the lake to cope. Excess nutrients produce huge blooms of algae that can turn the water green or brownish or reddish colors related to the pigments of the dominant algae. Excess nutrients can also throw the competitive advantage to less desirable types of algae - such as the blue-greens that produce toxic by-products or foul tasting or smelling products. As the excessive growth of algae eventually dies and sinks through the water column to the bottom, it can stimulate excessive decomposition down there by the bacteria, fungi, et al. As a result these oxygen-consuming microbes can strip the deep waters of the lake of its oxygen - driving higher quality oxygen-loving critters - trout, bass, etc. away (or killing them outright) - and favoring low oxygen tolerant "trash" species like carp, suckers, and catfish. Also anaerobic decomposition that follows proceeds at only 1/10th the rate of aerobic (oxygenated) decomposition, and it will produce products like H2S (rotten egg smell), NH3 (ammonia - toxic as concentrations build), CH3 (methane gas), etc. This human-accelerated eutrophication (since it still is nutrient enrichment driving (or over-driving) the process) is referred to as "cultural eutrophication", and is the process that all the septic system maintenance, and getting Phosphorus out of laundry soaps, keeping farmers from spreading fertilizers on still frozen ground, and Shoreland Protection Act regulations controlling the use of such stuff within a 100 ft of water bodies is all about.
So while oligotrophic bodies have less nutrients and productivity, the water is clear and tastes good. Reservoirs are managed to continue to be oligotrophic to keep treatment costs down.
Among the several fascinating questions emerging initially from our coring of Big PPP are these. How come the cored sediments some 20 ft beneath the current lake bottom are apparently so rich in organic matter (so dark brown in color)? The surrounding watershed is comparatively small, and its forest cover (especially until the "recent" development of the last 50 years) is usually good at holding back erosion and sedimentation - limiting the amount of import of sediments from outside the lake (i.e., so called "allochothonous material"). A clear-water, oligotrophic lake shouldn't be producing lots of organic matter within the lake (i.e., so called "autochothonous material") either. If anything, Big PPP has very poor growth of larger pond weeds. So where are all these organic rich sediments coming from???
Related to these issues, I've always pondered the "pea porridge" name for the pond. You'd think that would refer to a pond late in its eutrophic sequence - rich in nutrients and pea-soup green with excessive algae. In some ways, that could explain all the organic sediments we are coring. But eutrophication doesn't work in that direction - from lots of nutrients to few - unless there were some rich source of nutrients available in the past that has somehow been turned off in recent years?! But what that could be, I haven't a clue. Hmmmmm....many curious pieces to the story.
Lee
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