Dr. McColgan Dirt Sample

Here is a Dirt Sample given to our research group by Dr. McColgan. She was interested to see what elements may be found in her yard, so we used our skills in the SAInT Center to examine the dirt for her and find out. First, the dirt sample was very dark and well hydrated. We had to dry it out in the oven before looking at it under the Scanning Electron Microscope (SEM). The purpose of this is to remove all water from the sample because if not it will distort our data. Any water that may be in the sample when placed in the SEM can easily be seen skewing our data analysis. The SEM is the only machine we used that is water sensitive. The X-Ray Flourescence (XRF) or HD Prime is not water sensitive and below is our data obtained from it.

The XRF is a non-destructive analytical technique used to determine the elemental composition of materials. XRF analyzers determine the chemistry of the sample by measuring the fluorescent (or secondary) X-rays emitted from a sample when it is excited by a primary X-ray source. 

Below is the raw image of the dirt sample that we looked at under the SEM. You may notice some irregularities in the image of the sample. In some spots the image looks blurry or skewed, and we apologize. We believe that this may be because of some excess water still remaining in the sample. Even though we left the sample in the oven from 11:23am-1:38pm at a range from 104.5°F-106.3°F, the dirt still managed to retain water. Overall, the sample still provided us with a successful analysis.  

Below is the raw image as well as the element analysis on top of it. We color coded elements to make it easier for us to see what elements are where in our sample.

 When the raw image is removed it looks like the image below. Only the elements remain in the image below.

 Below is the spectrum of our sample. The spectrum helps us to see what elements are actually in the sample. Sometimes in the analysis of the sample initially, some elements may appear in the image, but not in the spectrum. These elements need to be manually removed to make sure our data is as accurate as possible. For this specific sample, we had to get rid of Oxygen, Carbon, and Zinc. Oxygen and Carbon must always be removed because they are found in the adhesive tape and cannot be accounted for. Zinc was found initially, but on the spectrum there was little to no bump. Therefore, it had to be removed from our data.

Below is our Microsoft Excel Spreadsheet of our dirt sample. By looking at the Normal Weight Percentages (norm. wt%) we can see that the element that was mostly found is Silicon(52.17%). Elements like Sodium(0.42%) and Sulfur(0.53%) were barely found. These percentages are a little off because when we remove major elements like Oxygen and Carbon the other elements' percentages get raised to account for it. Overall, the elements we found were Sodium, Magnesium, Aluminium, Silicon, Phosphorus, Sulfur, Potassium, Calcium, Titanium, and Iron. 

Bruker Nano GmbH, Germany				6/6/2016
	Quantax
Results	Soil/Dirt 1
Date:	6/6/2016
Element	AN	series	[wt.%]	[norm. wt.%]	[norm. at.%]	Error in wt.% (1 Sigma)
Sodium	11	K-series	0.166842317	0.42346555	0.575252218	0.038333473
Magnesium	12	K-series	0.550105072	1.396231789	1.794059074	0.058105604
Aluminium	13	K-series	7.083148859	17.97787024	20.80876716	0.380489085
Silicon	14	K-series	20.55680007	52.17559191	58.01764117	0.939273613
Phosphorus	15	K-series	0.524899439	1.332256909	1.343287257	0.047965921
Sulfur	16	K-series	0.211745376	0.537434828	0.523426687	0.03419496
Potassium	19	K-series	1.779920733	4.517649512	3.60852321	0.080661384
Calcium	20	K-series	2.073569294	5.262964319	4.101089316	0.087020899
Titanium	22	K-series	0.296523543	0.752611853	0.490898556	0.034394252
Iron	26	K-series	6.155710965	15.62392309	8.737055346	0.181731978
		Sum:	39.39926567	100	100

Something that we found exceptionally interesting and worth noting is that we found more Silicon in the sample than Carbon. If you refer back to the image of the spectrum you can see three major bumps that are clearly larger than the rest. These major bumps (going from left to right) are Carbon, Aluminium, and Silicon. The right most bump is Silicon, and it is clearly larger than the Carbon bump. This is intriguing because the adhesive tape we use to collect the samples is Carbon tape. For all of our other samples, Carbon is the most prominent bump in our spectrums. However, for this dirt sample in particular, Silicon is the largest bump.

Below is a picture we took of when we first discovered this. Dr. Kolonko joined us in our analysis of the sample. He confirmed that there was indeed more Silicon found than Carbon.

Overall, Dr. McColgan's Dirt Sample proved to be very interesting and beneficial to look at and we Thank her for letting us examine her dirt.