Dirt Samples in Siena Woods

As a part of the summer project to analyze some dirt samples using the SEM, we decided to collect some data from Siena itself. We collected the sample from the woods next to the friary. The following is a video of Tristen Protzmann collecting the sample from the woods.

For further clarification and verification we also analyzed the same dirt sample using the XRF HD Prime. 

The data that was obtained using the SEM is shown below;

The raw image of the section of the dirt sample we used to analyze the sample is shown below;

The image above shows a better picture of a sample of dirt we obtained. We can clearly identify the particles or sand.

The following picture is the data of the map of chemical composition that was obtained after running the X-ray for 9 minutes. The map also contains an outline of the raw image shown above.

All the elements that were found is represented using different colors. The map of chemical composition itself is shown below;

The results for the map shows very accurate readings. Remember that Carbon and Oxygen has been neglected from the calculations due its presence in the Carbon tape and its adhesive. In general, the goal when obtaining the data is to fill the dark spots as much as possible. The dark spots in the image above obtained after the scan represent places where C and O were present. The above image was filled when elements Carbon and Oxygen were included. Some elements were removed because of the insufficient the percentage of weight composition. 

We can clearly identify the location of the dirt using the element map itself. From the map itself we can conclude that the dirt (sand) has a excessive amount of Silicon.

The spectrum of the elemental composition for this particular dirt sample is shown below;

As predicted before there is large amount of Silicon compared to Carbon or Oxygen. A particular amount of Aluminium, Magnesium, Calcium and Iron is also found.

The raw data for this particular dirt sample is shown below;

Element	AN	series	[wt.%]	[norm. wt.%]	[norm. at.%]	Error in wt.% (1 Sigma)
Sodium	11	K-series	0.308793342	0.732120085	0.952649625	0.0479557
Magnesium	12	K-series	0.391885914	0.929124788	1.14357309	0.048852974
Aluminium	13	K-series	4.733096044	11.22172731	12.44166441	0.262844268
Silicon	14	K-series	30.28211244	71.79605167	76.47225685	1.371095323
Phosphorus	15	K-series	0.662497963	1.570720604	1.517017244	0.053941113
Sulfur	16	K-series	0.311531603	0.738612245	0.689060288	0.03822406
Calcium	20	K-series	1.155747413	2.740168842	2.045298919	0.060313921
Titanium	22	K-series	0.14078829	0.333795847	0.208551008	0.030172134
Iron	26	K-series	2.95020217	6.99465296	3.746725094	0.101191226
Cadmium	48	L-series	1.241308284	2.943025652	0.783203475	0.065317055
		Sum:	42.17796346	100	100

A 71.8% of Silicon was found, which is almost 3/4th of the elemental weight composition of the whole sample. The other primary element that is found is Aluminium with a percentage of 11.2%

The potentially harmful substance that was found is Cadmium. Cadmium is a soft, malleable, bluish white metal that is usually found in the Zinc Ores. There are some harmful effects from the element.

"Occupational exposure to cadmium can lead to a variety of adverse health effects including cancer. Acute inhalation exposure (high levels over a short period of time) to cadmium can result in flu-like symptoms (chills, fever, and muscle pain) and can damage the lungs. Chronic exposure (low level over an extended period of time) can result in kidney, bone and lung disease."

References;

https://www.osha.gov/SLTC/cadmium/index.html

The next analysis done is using the XRF HDPrime. For a larger amount of dirt, the HDPrime will give you better results regards to the composition. The SEM looks in the sample in a molecular level. The HD Prime uses X-rays to penetrate the sample and identifies the elements in the sample.

The Results that were obtained using the XRF HD Prime is shown below. The cam view (wide view, Side view) of the sample is also included in the data. The row of elements after the view shows the common elements that are expected to be seen in the sample. However to get a accurate results, we should look into the full results table shown in the second image. We will be looking into the counts column in this part to identify the elements with the most amount of counts that were detected.

From the full results seen above, we observe 195,498.6 counts of Iron which is the most significant amount of substance that was found in the dirt sample using XRF HD Prime. There was also 24,261 counts of Strontium found in the same dirt. Strontium is a soft, silvery metal that burns in air and reacts with water. It is commonly used in fireworks because of the red flare its salts give out. It's not known to be dangerous or toxic but it does have radioactive isotopes. 

References;

http://www.rsc.org/periodic-table/element/38/strontium

The advantage of using the HD Prime is that there is a better chance of detecting elements with a bigger atomic number. The grid of elements that is found in the first picture are common elements that are found in samples. The green color in the grid represents that there is only a moderate amount of the element found in that sample. The other possible colors can vary from orange to Red mentioning that there is an excessive amount of a specific element detected as the colors become darker starting with green, yellow....ending with Red.

The Results from the SEM and the XRF HD Prime do not really correlate because they are different types of instruments. The SEM uses weight composition to measure the amount of elements present in a sample whereas the HD Prime uses counts (parts per million). However, measuring more data using a different type of instrument makes analyzing the data more comprehensive.