After spending a while learning our way around the Caylor lab and bouncing between miscellaneous short-term tasks, my two fellow Princeton interns (Princeterns?) and I were each assigned an individual project to focus on for the rest of the summer. As I have possibly mentioned before, the Caylor lab group is working on modeling the hydrologic cycle of the dry savannah ecosystem, an endeavor that requires collecting data on several different subsets of the ecosystem. So for the next two months, Alice will be collecting data on vegetation, Kathleen will be collecting data on rainfall, and I will be collecting data on soil.
Alice (left) and Kathleen
One of the major components of my project involves a lab experiment designed to investigate the way water percolates through sandy savannah soil. The plan is to fill six big plastic buckets with the savannah sand, pour water into the buckets, and then use a bunch of devices and sensors to track the water as it moves through the sand and out the drainage hole.
Sophisticated science in action |
For the past ten days or so, though, there’s been an activity lull as I’ve been waiting for all of the sand for my buckets to oven-dry. Since our oven capacity is limited, since all of the sand must spend at least 24 hours oven-drying, and since I have a crapload of sand to dry, this is taking a while.
In the interim, I’ve been trying to understand devices. Professor Caylor seems to have a bit of a penchant for devices: soil moisture probes, infiltrometers, temperature sensors, isotope analyzers, water potential sensors, and so on.
A sampling of devices. Clockwise from top left: a datalogger, a Mini Disk Infiltrometer, the WP4 Water Potential Sensor, and an EnviroSense Soil Moisture Probe
Kind of like this |
Case Study: My current device, the HYPROP
The HYPROP in action. Don't be fooled by its deceptively simple appearance. |
Answer: Use this device to find out how tightly different kinds of dirt hold on to water.
To set up the HYPROP, you first have to remove the dissolved gas from several different water samples using a system of hand-operated vacuum syringes and tubes. The water must be left to degas for a minimum of two hours, but preferably longer. The manufacturers recommend a full day. Then you have to screw the two Tensiometer shafts into the base, but do NOT touch the ceramic tips with your fingers. Or let them dry out. Or let them come into contact with non-distilled water. Also, when you’re screwing in the Tensiometers, be aware of the pressure sensor inside the base: “It is very sensitive and must never be touched! It can be destroyed even by slightest contact.” Now saturate your soil sample for a minimum of 24 hours. And then put the whole thing on a digital balance connected to a computer by a cable, but be careful, because “even a breeze can move a dangling cable causing variance in the measurement.” Finally, let the HYPROP sit for a week to take measurements until it is fully air-dried, but make sure to check the data-logging software constantly, because it tends to go buggy and suddenly stop collecting measurements.
And then you know what you get from this whole process? One sample.
I’m plugging through on my own, but I miss my Princeton engineering team. You know who you are.
SIDE NOTE: The secretary bird is a large, mostly terrestrial raptor endemic to sub-Saharan Africa. It is the only raptor to hunt prey on foot, which it kills either by striking with its beak or trampling with its feet. It is by far my favorite African animal, and I wanted to share the great picture I got of one a little while back:
You got to see a wild secretary bird? Damn, that's cool.
ReplyDeleteNever has there been such a discrepancy between coolness of common name and coolness of Latin name.
Common name: Secretary bird.
Latin name: Saggittarius Serpentarius.
Bad. Ass.
Hi! What a great description of what you are doing! Although to my seriously non -engineering brain, it makes no sense whatsoever. Good for you for persevering and learning all about those barely decipherable machines.
ReplyDeleteLove the secretary bird, he looks very cool. How big is it?