Summary on XRF

SUMMARY ON XRF

XRF works through the process of exciting electrons within an atom. Generally, waves of high energy and low frequencies are used (x-rays or gamma). When the electron within an atom becomes excited, it then ejects from the atom. As a result the atom becomes unstable and an electron from an outer shell must fill the spot. The difference in energy levels between the the electrons is then released in the form of photons. Each element releases a specific energy and that is how we are able to identify elements.

I must have read this summary about a thousand times by now. Yet, looking especially at what I underlined, " When an electron within an atom becomes excited, it then ejects from the atom", a question was raised. I was requested by Dr. McColgan to then find out what energy level is needed to eject the electron. Also, why does the HD Prime need three energy levels in the form of x-rays to complete its task? What amazed me was the lack of detail many articles went into about ejecting at electron.

Finally I found my answer.

First I have to say, let's forget about the math. To put it in simplest terms, we know that there are several shells within an atom including: K-shell, M-shell, and L-shell. Within each shell there are electrons, all of which have their own energy level (that is the closest we will get to math). To knock an electron out, all we need is for the x-ray to have an energy level at least the same amount as the electron we intend to knock out. 

So then why don't we just use a really high energy level to get all of the electrons to react?

Yes, by doing that you would get all of the elements to react and release electrons, but it would be very hard to identify all of the elements. Especially when looking at an energy level graph, all we would see is an overlapping of peaks. Thus, we would be unable to identify all of the elements, especially those that would only require a small amount of energy to react. That is why the HD Prime has three energy levels. As the energy output decreases, elements that require lower amounts of energy will react stronger and we will be able to see them. Also, with the three energy levels we will get K, L, and M series. This way if we are still getting overlapping we could look at a different series to identify the element.

Side note:

X-ray fluorescence has come a long way in the world of atomic physics. It amazes me what I have accomplished in these eight weeks. Thank you so much for the opportunity and I hope what I have recorded will help the next student along the way in his or her research.

Reference Samples and Data

Intro: 

You might remember awhile ago when I was testing the calibration of the machine by using a tile that contained 5 metal samples and a plastic sample. But, because m1y study focuses on both aqueous and soil samples, I need to test the limits of detection using liquid, certified reference materials. I have already tested lead, nickel, chromium, and cadmium using AA standards. I just bought arsenic, mercury, and antimony to test.

How checking the calibration of the machine works is by creating a sample in which you know the exact measurements in it. Using simple math you could calculate the ppm for an element you wish to put into a sample, measure it out in a syringe, and put it into the HNO3. Then when you run it through an x-ray analyzer, you would know what to expect for numbers. What we need to be cautious of is the LOD (limits of detection). The LOD tells us the lowest concentration (ppm) that an element can be examined in a sample. For my CRMs they are:

Sb= 6 ppm

As=.2 ppm

Hg=None

What this means is if I go below the LOD, the x-ray analyzer will not be able to pick up on the concentration. That is why we created a calibration sample that contains the following:

Sb= 9.89 ppm

As=10.10 ppm

Hg=10.04 ppm

Data:

A large concentration of the reference material was created.  I then put the reference material into four different measuring samples that were individually run through the x-ray analyzer. A total of nine data sets were collected throughout the four samples. The numbers calculated included:

Sb= 12.9, 13.3, 14, 13.3, 18.7, 14, 11.9, 16.1, 12.8 (ppm)

As= 2, 2.2, 2.2, 2.1, 2.2, 2.1, 2.3, 2.1, 2 (ppm)

Hg= 3, 3, 2.9, 2.6, 2.9, 3, 2.8, 3.1, 2.7 (ppm)

Conclusions:

The data does not seem very close to the expected values. Because of this, I now need to have the machine calibrated and adjust all values for experiments done. 

Al-Tech Steel and the Kromma Kill Watershed

Intro:

The Albany area is supported by the Kromma Kill Watershed. Al-Tech Steel was a hazardous factory that closed in 1994 (http://wikimapia.org/1836689/Al-Tech-Steel-Abandoned). It has since become a Superfund site. By "superfund", I mean a hazardous brownfield that must be cleaned up as part of the Superfund Act in order to protect human health. The EPA plans to clean the area in 2015. Below is a photo of the factories area (Siena College is under the zoom key).

Figure 1. Al-Tech Steel area.http://wikimapia.org/1836689/Al-Tech-Steel-Abandoned

Figure 2. Al-Tech steel.
http://blkmsk.pvdind.com/explore.php?id=00000000014

The company was famous for using heavy metals within the factory (especially nickel). But, because the factory used heavy metals for so many years and now they are just sitting there until clean up, it is expected the hazardous waste is going into the soil. That is why I collected soil samples from areas around the outside of the abandoned factory. Using X-ray fluorescense I will test the quality of the soil and make infrences on how the company has affected the area. 

Figure 4. Factory side of the street.

Figure 5. Across from the factory.

Besides soil, a stream that collects a large amount of water throughout the Kromma Kill watershed is just across the street from the factory. In figure 3, the stream is behind the trees which is just across the street from the factories main gates. What is important is that the stream then dumps into the Hudson River, but not before traveling through several neighborhoods. If the water comes back with dangerous levels of heavy metals it could already be endangering the locals' health.

When I was examining the stream I noticed an area dumping into it as well. That is why I also decided to test the dumping water as well as the stream water.

I ended up collecting just four samples (mainly because I only had enough room to carry that many). I collected soil from an area close to the factory gates and next to the stream. Then I collected one water sample from the stream and one from the dumping area. Each sample was run through the HD Prime 3 times. If any samples came back significantly high, I will then go out to form a larger study on the topic. I will decide what constitutes high levels based on the average soil chart  I used before and the standards for aquatic life in water. Below are the charts I will be using.

Charts:

Figure 6. Average element concentrations in soil.Comparing Soil Samples from the Albany Pine Bush to Average Soil Contaminants

Figure 7. Limits for trace elements allowed in water for aquatic life.Comparing Soil Samples from the Albany Pine Bush to Average Soil Contaminants

Data/Soil:

Figure 8. Factory soil 1.

As above average, Zn above average, Cr above average, Cu above average, Mn above average, Ni above average, Pb above average, Rb above average, Sb above range,

I could not find any thing on Fe, but I did read that a lot of it comes from steel mills.

Figure 9. Factory Soil 2.

As above average, Au above average, Cr above range, Cu above range, Mn above average, NI above average, Pb above average, Rb above average, Sb above range, Zn above average

Fe seems high

Figure 10. Factory Soil 3.

As above average, Cu above range, Cr above range, Mn above average, Pb above average, Rb above average, Zn above average

Fe seems high

Figure 11. Stream Water 1.

C above average, Cu above average, Mn above average, Ni above average, Pb above average, Rb above average, Zn above average

Fe seems high, but not as high as other soil 

Figure 12. Stream Water 2.

As above average, Ba above average, Cr above average, Cu above average, Hg above range, Mn above average, Ni above average, Pb above average, Rb above average, Sb above average, Zn above average

Fe seems high, but not as high as factory soil

Figure 13. Stream Water 3.

As above average, Cr above average, Cu above average, Hg above range, Mn above average, Ni above average, Pb above average, Rb above average, Ab above average, Zn above average

Fe seems high, but not as high as factory soil

Data/water:

Note: Cr can be as high as 20 ppm in rivers, but most often around 5 ppm. Pb has a zero tolerance level. These things are not listed in the chart.

Figure 14. Drain Water 1.

Pb and Sb are high. Assuming Cl is high

Figure 15. Drain Water 2.

Pb is high. Assuming Cl is high 

Figure 16. Drain Water 3.

Pb is high. Assuming Cl is high

Figure 17. Stream Water 1.

Sb is high. Assuming Cl is high 

Figure 18. Stream Water 2

 Sb is high. Assuming Cl is high

Figure 19. Stream Water 3.

No data.

Conclusions:

Based on observation, i would say that both sample sets contained soil that was well above safety regulations. Surprisingly the water was not nearly as toxic as I suspected. Elements that concern me are Fe, Hg Pb, and Sb. Fe came in very large quanitties. Online I found that any substance where Fe makes up half of it or more is considered lethal. Several samples of soil also contained Hg which is very alarming. Lastly, Pb and Sb constantly appeared to be to high in both soil and water.

Graphs on Albany Pine Bush Water and Soil Samples

SOIL

After plugging in all of the data points collected from the Albany Pine Bush, you can see a comparison of element concentrations between soil samples. The graphs show the amount of each element found within the samples. Note that each sample was ran twice on default (example: sample 1 and 1.2) and once on extended (example: sample 1E). The first graph mainly shows the highest element concentrations. In the second graph I deleted the two highest element concentrations (Ba and Cl) so that smaller peaks could be observed.

To get an even closer view of the remaining elements I again deleted the next two largest elements (Sb and Pb).

Again I deleted the next highest element (Cr). Also note because Hg and Cd only had ND as its results, no numerical stat apeared. ND stands for "no data", but what that actually means is the concentrations were so low they could not be detected.

From these graphs we can see just how much higher the concentrations of Ba and Cl were as compared to any of the other elements. We as well can visually see which elements had lower concentrations (As, Br, Cd). Although Ba and Cl were the highest, they had large variation as compared to Cr and Sb that were consistent throughout the samples. Below is the data I collected on the averages of all the elements. One thing that should be noted is that the averages only include data from numerical values and ignored ND. Because ND generally is a very low amount, the averages are not very reliable.

WATER

For the water samples I used the same idea when making graphs. The first graph includes Cl that was very high only in one sample. In the second graph I removed Cl so that other elements can be looked at.

Below is also the averages computed for each element. Again the averages only included data with numerical values and ignored ND.

Comparing Albany Pine Bush Water and Soil Samples to Each Other

Comparing Albany Pine Bush Water and Soil Samples to Each Other

 Into:

After examining the Albany Pine Bush's water and soil independently, I will now compare them to each other. The water samples came from a natural well and the soil samples came from close by (approximately 1 m away from each well). I can look to see if there is a pattern with the soil and water, where they share high concentrations of the same elements. With these comparisons I will be able to link data sets produced from the HD Prime. A strong link would prove both the accuracy of x-ray analysis, but also that correlation between water and soil.

Data:

• Note- The first data set belongs to soil and the second one is water's. Also I will be referring to                   comments made from previous blogs.

Sample 1-

 Low shrub area, houses near by

Both sets have high levels of Sb.  While in soil Cl is high, Cr is relatively high in water.

Sample 2- 

Shrub/wooded area, recent control fire

Cl ia above average is soil along in soil and most likely water. Both have high levels of Sb. 

Sample 3-

Shrub/wooded areas, control fire, near highway

Sb is high is soil, but not in water. Cr and Ba is high in water.

Sample 4-

Same as 3

Sb is high in soil, Cr is high in water.

Sample 5-

Low shrubs, near landfill

Sb is high in both samples. Cr is high in water.

Sample 6-

Same as 5, also near wetlands

Sb is high in soil. Cr is high in water as well as Pb (has a zero tolerance law).

Sample 7-

Same as 6

Sb is high for both and Ba is relatively high for both.

Sample 8-

Same as 6

Sb is high for both. 

Sample 9-

Especially close to landfill

Sb is high in soil. Pb is an issue in water.

Sample 10-

In swamp, near landfill

Ba readings are high in soil. Sb is high in both.

Sample 11-

Same as 10

Sb is high in both sets. Pb is an issue in water.

Sample 12-

Near Albany Pine Bush Center, close to parking lot

Ba is high in soil. Sb is high in both sets.

Conclusions:

Seeing as almost every sample came back with high Sb readings, it would be safe to say that Sb is an issue in the area. 8 of the 12 sets came back with readings that were high for specific elements in both the water and soil (example: both had high Sb readings). As well, water with high Pb readings came from landfill areas. There does not seem to be any outstanding concentrations of heavy metals from areas closer to the landfill as compared to wooded/natural areas. My best guess is that there is leeching going into the soil first that then makes it into the water. This becomes more apparent when the heavy metal concentrations is almost always higher than the water readings.