WEBVTT 00:00:00.000 --> 00:00:02.000 Well, thank you very much. And Hi, everyone, I'm Rona. 00:00:02.000 --> 00:00:16.000 Iri was nephk, and today I'll be talking to you about compound specific isotope analysis for both source identification and cy characterization. 00:00:16.000 --> 00:00:30.000 So, as the name says, compound specific isotope, analysis, we'll be looking at isotopes in compounds and not analyzing I built in compounds to help us identify the source of these compounds. 00:00:30.000 --> 00:00:42.000 And these chemicals. So first, we're gonna take a short trip back to either high school or college chemistry and remind ourselves what our isotopes. 00:00:42.000 --> 00:00:49.000 So Isotopes, if you remember, atoms, elements like carbon, will use carbon for this discussion. 00:00:49.000 --> 00:00:57.000 They have the same number of proons. And they have protons and neutrons in their nucleus. 00:00:57.000 --> 00:01:13.000 Isotopes, however, have the same number of protons in their nucleus, but different number of neutrons, and the sum of the protons and the neutrons gives us the mass, and that just tells us the mass of the itself. No. 00:01:13.000 --> 00:01:16.000 Isotopes can be stable, or they can be radioactive. 00:01:16.000 --> 00:01:24.000 Carbon itself can have, I think, up to 20 isotopes, but only 3 of them actually exist in nature, and 2 of them are stable, and one is radioactive. 00:01:24.000 --> 00:01:28.000 The stable isotopes carbon, 12 and carbon, 13. 00:01:28.000 --> 00:01:38.000 That is what we will be using. We will be measuring for our compound specific isotopen, as these do not underco radioactive decay. So they're there. 00:01:38.000 --> 00:01:46.000 They're stable and available for us to measure. 00:01:46.000 --> 00:01:53.000 Okay. So a little bit more about what is compound specific isotope analysis. 00:01:53.000 --> 00:01:59.000 So this is where we measure the ratio of those stable isotopes that I just showed you. 00:01:59.000 --> 00:01:59.000 So looking at this people that I have at the bottom here, back to carbon. 00:01:59.000 --> 00:02:15.000 Remember, carbon had 2 stable isotopes, carbon, 12 and carbon 13 in nature, typically the lighter, but the lighter isotope is more abundant, so carbon 12. 00:02:15.000 --> 00:02:18.000 You see here in nature, it's 98. 00:02:18.000 --> 00:02:32.000 Percent. And whereas carbon 13 is just 1%. So let's say this picture here and hopefully you can see my cursor let's say this is like a mug of Tc, most of the carbons in that Tc would be carbon dioxide. 00:02:32.000 --> 00:02:44.000 And just about 1%, also with carbon, 13 so the isotope ratio is actually the ratio of the heavy to the light isotope carbon, 13 to carbon, 12. 00:02:44.000 --> 00:02:51.000 You, you can apply this to several different contaminants for inated solvents, which will give hydrocarbons, pesticides, and we can use Csi for source identification, which we will talk about today. 00:02:51.000 --> 00:03:01.000 And also to determine degradation. 00:03:01.000 --> 00:03:15.000 So next measuring isotope analysis. So you can do this in groundwater sample soil, air, sample, an example where you can extract your chemical out of it, and shoot it into a Gc. 00:03:15.000 --> 00:03:21.000 You can measure for isotope analysis. Typically, we use. 00:03:21.000 --> 00:03:25.000 Gc, I, R. M. S. Or Gcms, just so, you know. 00:03:25.000 --> 00:03:30.000 And if the data would be represented as Delta C. 00:03:30.000 --> 00:03:36.000 13. This is important, because during this presentation I will refer to this Delta C. 00:03:36.000 --> 00:03:42.000 13, or whatever elementary. Looking at Delta, chlorine, I will refer to it several times in the presentation. 00:03:42.000 --> 00:03:45.000 So so this is pretty important here. So the Delta C. 00:03:45.000 --> 00:03:59.000 13. They usually calculate that by measuring the ratio in the sample, and then comparing it to a standard, and then multiplying that by 1,000. 00:03:59.000 --> 00:04:02.000 So for carbon, it would be carbon sitting over common 12. 00:04:02.000 --> 00:04:10.000 Alpha was sample, minus carbon, 13 over carbon, 12 of of our standard and delta is usually negative. 00:04:10.000 --> 00:04:18.000 The reason why delta is negative is because our sample is usually lighter than the standard that has been chosen. 00:04:18.000 --> 00:04:22.000 The standard typically chosen for carbon. You'll see the Pdb. 00:04:22.000 --> 00:04:34.000 If you see that in the graph size, show that simply says data was collected in reference to this standard, and then for chlorine it's standard mean ocean coloring, as Moc. 00:04:34.000 --> 00:04:34.000 And the units. The units of this Delta, 13. 00:04:34.000 --> 00:04:44.000 Is per mill parts per 1,000. You could think of it as a percent which is parts for 100. 00:04:44.000 --> 00:04:53.000 But in this case we use parks per 1,000 because we're dealing with really small, really small changes and differences. 00:04:53.000 --> 00:05:01.000 So the Delta, c. 13, cl. 37. Whatever you're looking at will be a number like minus 30. 00:05:01.000 --> 00:05:20.000 And what that means is that your sample is 30% lighter than the standard that was used so what I want you to get from this slide is you'll be seeing Delta C, 13 or Dl 37 or H one throughout the presentation it's gonna be a negative number and it's compared to a 00:05:20.000 --> 00:05:26.000 standard, and it's usually less lighter than that standard. 00:05:26.000 --> 00:05:34.000 So in terms of benefits and limitations of Csi it's pretty sensitive and can detect some subtle differences. 00:05:34.000 --> 00:05:49.000 It's very useful in fingerprinting, and often it doesn't rely on concentration trends, limitations you can't use it for age dating. It's not gonna tell you how old your chemical is and if you're measuring 2 different sources it's not going to 00:05:49.000 --> 00:05:55.000 tell you there's a lot more of one source than the other source. 00:05:55.000 --> 00:06:04.000 Cool. Csi really tells you, if 2 samples are isotopically different or not. 00:06:04.000 --> 00:06:24.000 Okay. So now, that we've gone through the basics, let's jump into what we wanna know and how we can use Csi for source identification and site characterization so Csi can be used on several different contaminants of concern earlier in the presentation. 00:06:24.000 --> 00:06:32.000 I showed you that table there are isotopes of carbon, hydrogen, oxygen, chlorine. 00:06:32.000 --> 00:06:32.000 I know a few different additional elements. So as long as your chemical has these elements, you can typically do, stabilize it. 00:06:32.000 --> 00:06:46.000 Top analysis on it, you can differentiate between whether degradation is taking place or if it's just dilution. 00:06:46.000 --> 00:06:46.000 Sometimes we see reduction in concentrations, but it's just dilution. 00:06:46.000 --> 00:06:57.000 Csi will be able to tell you the difference. Then Csi should be used in a multi-line of evidence. Approach. 00:06:57.000 --> 00:07:04.000 It's not standalone. You need to collect other data like chemical data. 00:07:04.000 --> 00:07:12.000 Geo-chemical data, and it can differentiate between different sources and the reason why which I have in this key point. 00:07:12.000 --> 00:07:32.000 The reason why you can differentiate between different CC sources is typically the isotope ratio of a chemical is dependent on both the raw material that was used to make that chemical and also the manufacturing process so often different manufacturers the chemical they produce would have 00:07:32.000 --> 00:07:38.000 different isotope ratios. No, you and the beginnings of Csa. 00:07:38.000 --> 00:07:41.000 When we realized that that was a slam down for us. 00:07:41.000 --> 00:07:47.000 But then we found out, even between batches of different chemicals, you can have different isotope analysis. 00:07:47.000 --> 00:07:56.000 But then we had to take another another look at how we would interpret this data. 00:07:56.000 --> 00:08:06.000 So this graph just shows you what the isotope ratio of different chemicals from different manufacturers, how much it can actually vary. 00:08:06.000 --> 00:08:16.000 So you look at PC. E. Here from 11 different sources, and it can range from minus 25 all the way to minus 35. 00:08:16.000 --> 00:08:20.000 That's a pretty wide range you look at choral form C, 13. 00:08:20.000 --> 00:08:30.000 For chloroform, 4 different samples. These are just 4 samples and it ranges from minus 45, and by to minus 16. 00:08:30.000 --> 00:08:43.000 So you see here, even with the delta of chorine, we have a pretty wide range here for tce from plus 4 to minus 4, and even for 1 1 one Tca. 00:08:43.000 --> 00:08:55.000 So yes, these differences happen. But we'll talk about how we can overcome this when we analyze Dsia, first source identification. 00:08:55.000 --> 00:09:09.000 Oh, if you if the person who received the chemical to copious notes recorded a manufacturer, the batch number, the even saves a little bit of the chemical in the warehouse, feed analyze later. 00:09:09.000 --> 00:09:09.000 That's great, wonderful! But we know that very, very rarely happens. 00:09:09.000 --> 00:09:19.000 Typically, we don't have pretty good history on any of the chemicals we have. 00:09:19.000 --> 00:09:29.000 So if it's not known, if you don't know this information, or even if you know it, you should consider analyzing multiple elements. 00:09:29.000 --> 00:09:34.000 Typically we just do custom 30 or chlorine, 37. 00:09:34.000 --> 00:09:48.000 But if you don't have a lot of history on your contaminant, we recommend doing multiple elements chlorine and carbon for chlorinated solvents and carbon and hydrogen for hydrocarbon. 00:09:48.000 --> 00:09:52.000 And this definitely increases the validity of your data. 00:09:52.000 --> 00:09:59.000 And as we go through the presentation we'll see how this kind of helps us with the data. 00:09:59.000 --> 00:10:03.000 So look at this graph here. So this shows us Delta C. 00:10:03.000 --> 00:10:11.000 13, and delta chlorine 37, looking at different manufacturers let's look at Tca first. 00:10:11.000 --> 00:10:17.000 So Tca. From Ppg. In 1999, 95. 00:10:17.000 --> 00:10:20.000 So Delta c. 13 is pretty close on the same manufacturer. 00:10:20.000 --> 00:10:27.000 However, when we look at the Delta C L. It varies quite a bit. 00:10:27.000 --> 00:10:31.000 So if we had analyzed just the cl. 37, we would think, okay. 00:10:31.000 --> 00:10:32.000 Oh, this must be pretty different, maybe a different manufacturer. 00:10:32.000 --> 00:10:50.000 But we can see the same manufacturer how the Delta varies with the cl, and it's the same for the carbine and then look at Tca here like a tce made by Dow. 00:10:50.000 --> 00:10:57.000 The C. 37 is pretty close, but then, when we look at the common 13, it varies it very spite a bit. 00:10:57.000 --> 00:11:12.000 So this is why we say, analyze more than one element when you're doing conf one specific isotope analysis, especially if you're trying to do source identification. 00:11:12.000 --> 00:11:16.000 So next we'll talk about sampling for Csi. 00:11:16.000 --> 00:11:16.000 Oh, remember thinking of sampling first. You need to know as much site history as you can. 00:11:16.000 --> 00:11:25.000 There any remediation done, any injections, instructions? 00:11:25.000 --> 00:11:29.000 Is there ground water, extraction, treatment system that could have? 00:11:29.000 --> 00:11:34.000 Taken contamination from one place, and maybe even deposited it elsewhere. 00:11:34.000 --> 00:11:58.000 So investigate your site history as much as possible, and then design your sampling strategy based on the conceptual site model, and where you think your sources are me, recommend at least 3 samples within your source, whether it's groundwater or soil or air we recommend taking at least 3 which it 00:11:58.000 --> 00:12:17.000 within the source. If you have an apple, definitely measure your apple or Csi of carbon and hydrogen, and then you wanna take samples across your plume as well follow the groundwater flow path and take some samples around that groundwater flow path and see what they isotopic 00:12:17.000 --> 00:12:26.000 ratio. Looks like with Csi. The higher the concentration of your contaminants, the better the data. 00:12:26.000 --> 00:12:43.000 This graph that I show here to the right. So this is actually the study done by done by Apa, that showed if they had really low concentrations of the chemical in water, the noise in the isotope data was pretty large. 00:12:43.000 --> 00:12:47.000 If you have like, point one or point 2 micrograms per liter. 00:12:47.000 --> 00:13:06.000 So it tends to work best when you have concentrations of about point 2 or greater maybe greater than even point 5, then you will get much less variability in your data and your your isotope ratio is more valid at that point. 00:13:06.000 --> 00:13:14.000 So keep that in mind. You need slightly higher consensations to have good Csi data. 00:13:14.000 --> 00:13:18.000 So how can we use Csi in forensics? 00:13:18.000 --> 00:13:32.000 We can use it for methane to differentiate methane sources, whether it's from biodegradation or from from gas, pipeline gases, methane tends to be lighter. 00:13:32.000 --> 00:13:38.000 Isotope, because it's coming from Cs, just because it's coming from food oil. 00:13:38.000 --> 00:13:42.000 Then there's perchlorate. It could be natural, synthetic. 00:13:42.000 --> 00:13:51.000 Some of you may have heard of the chlorate and the the Chilean fertilizers, and and that that crooked existed naturally. 00:13:51.000 --> 00:13:57.000 So there's a difference in the signature between preclorate whether it's natural or synthetic. 00:13:57.000 --> 00:14:06.000 We talked about vocals already where we saw multiple sources at different signatures, and then nitrate nitrate can have a few different sources. 00:14:06.000 --> 00:14:13.000 So it's important to understand the source. So we can interpret the Csi data. 00:14:13.000 --> 00:14:24.000 So now we're gonna look at a few of these here to see how we can use Csi to differentiate these sources. 00:14:24.000 --> 00:14:30.000 First thing we're gonna look at is perchlorate. 00:14:30.000 --> 00:14:30.000 And I tried to put the reference where I got a lot of this information on the slide. 00:14:30.000 --> 00:14:34.000 If it's not on the slide, it's gonna be at the end of the presentation. 00:14:34.000 --> 00:14:46.000 If anybody wants to do any additional reading after so synthetic per chlorate, the man made perchlorate. 00:14:46.000 --> 00:14:54.000 Tends to have oxygen. 18 signature that ranges from about minus 10 to about minus 30 or so. 00:14:54.000 --> 00:15:00.000 That's a pretty wide range, which is wrong. Why, we want to do also chlorine 37. 00:15:00.000 --> 00:15:12.000 Notice the chlorine, 37 of the synthetic perchlorates hangs around right at this 0 there was a natural perchlorate that's coming from minds, and may have come from fertilizers. 00:15:12.000 --> 00:15:21.000 Thanks to have a lighter chlorine, 37 more around the minus 10. 00:15:21.000 --> 00:15:35.000 So these lines that you see here, that's what happens when these compounds decrease, when they degrade, it becomes more and more less sorry, less negative or heavier. 00:15:35.000 --> 00:15:40.000 So let's say you had taken a sample, and you got a result around here. 00:15:40.000 --> 00:15:47.000 Let's say, I understand chlorine 37, and about 708 oxygen, we would say. 00:15:47.000 --> 00:15:55.000 Most likely that sample came from a natural, and it has undergone some type of degradation. 00:15:55.000 --> 00:15:58.000 So you see, it's a really important to understand the history. 00:15:58.000 --> 00:15:58.000 Where did the perchlorate come from, or the Csa. 00:15:58.000 --> 00:16:12.000 Can help you figure that out. So this is one way you can see how perchlorate differs, whether it's synthetic or it's natural. 00:16:12.000 --> 00:16:20.000 Okay, so next for tce, a Tc study here. So this side had 2 hotspots. 00:16:20.000 --> 00:16:31.000 PC. Will present it very close to concentrations. 00:16:31.000 --> 00:16:31.000 So we think Deafa was present. Very few daughter products, and there were 2 political zones at this site. 00:16:31.000 --> 00:16:37.000 Well pretty complex site. So the question was, is the contamination in the lower zone? 00:16:37.000 --> 00:16:42.000 Is that coming from the upper zone? Is it a separate source? What's happening? 00:16:42.000 --> 00:16:50.000 What is happening as this contamination moves. So let's take a look at this and see what we found out. 00:16:50.000 --> 00:16:56.000 So here, 6. Different wells, round water comes. 6 different wells was analyzed. 00:16:56.000 --> 00:17:02.000 PC. Concentrations were measured and also carbon isotope ratio was measured. 00:17:02.000 --> 00:17:10.000 In this case only one element was looked at. Carbon. That's the only element that was looked at here so let's take a look at the opera zone. 00:17:10.000 --> 00:17:19.000 This is in the source area, upper zone concentrations 390,000 micrograms per liter. 00:17:19.000 --> 00:17:22.000 So this here is telling us, okay, I think we have some here. 00:17:22.000 --> 00:17:28.000 Then we go to the lower zone. Concentrations lower 15,000 micrograms per liter. 00:17:28.000 --> 00:17:34.000 But the signature is quite different. It's a minus 32 per mill. 00:17:34.000 --> 00:17:36.000 So we see the upper zone has a minus 38. 00:17:36.000 --> 00:17:39.000 The lowestone has a minus 32. 00:17:39.000 --> 00:17:44.000 I would consider that pretty pretty different. So we go to the lower zone. 00:17:44.000 --> 00:17:54.000 Now the lower zone. We have a 48,000 concentration low zone, one and lower zone, 2, 3, 7,000, and look at the signature lowestone. 00:17:54.000 --> 00:17:58.000 One signature is a minus 38 per mill. 00:17:58.000 --> 00:18:01.000 Low zone, 2 is a minus 33 per metal. 00:18:01.000 --> 00:18:13.000 So what are we seeing here? We're seeing that the signature of Upper zone, one and low zone, one very similar, minus 38, minus 38. 00:18:13.000 --> 00:18:23.000 The signature of Upper zone, 2 lower zone, 2 very similar, minus 32, and minus 33, so that's that's significant. 00:18:23.000 --> 00:18:32.000 Let's keep that in our mind. The upper and lower zones of the sources are very similar when they're right under each other. 00:18:32.000 --> 00:18:36.000 Okay. Now, we're trying to move it down, down the plume signature. 00:18:36.000 --> 00:18:42.000 Minus 35, minus 35, okay, minus 35 is between the minus 38 and minus 33. 00:18:42.000 --> 00:18:48.000 So we're trying to figure out, okay, what's going on here? 00:18:48.000 --> 00:18:53.000 Our concentrations 13,000, and then 49,000. 00:18:53.000 --> 00:19:01.000 How many times at sites we see data like this. Hi, concentration, in sauce, then a decrease is downgraded, and oh, there it is! 00:19:01.000 --> 00:19:05.000 It's going up again, and we're trying to figure out what's going on. 00:19:05.000 --> 00:19:14.000 Combining these data. Csi, as well as chemical data as well as geochemical data, can help us figure out what's going on. 00:19:14.000 --> 00:19:19.000 So the conclusion here was that they were 2 different Hotspots, and the upper and lower zone contamination was from the same hotspot. 00:19:19.000 --> 00:19:35.000 So upper zone, lower Zone had some subtype of interaction that the hotspot was leaking down your Dean apple was leaking down. 00:19:35.000 --> 00:19:52.000 Carmen only Csi. In this case he was sufficient information to know that I was sources was the same in the up and low zone, but we had 2 different 2 different sources, same as the upper and lower zone in terms of what's going on in the Downgradient wells we need some 00:19:52.000 --> 00:19:59.000 more information, to really see what's going on, but it seems that it may be influenced by both Hotspots. 00:19:59.000 --> 00:20:04.000 The additional information I would recommend in this case would be daughter products. 00:20:04.000 --> 00:20:16.000 Dce. Final chloride. Do we have those showing up we have the concentrations so that the geochemistry isn't does the geochemistry fit some type of degradation? 00:20:16.000 --> 00:20:21.000 So I'd recommend looking at that. 00:20:21.000 --> 00:20:26.000 So, then, looking at nitrate, nitrate can come from few different sources. 00:20:26.000 --> 00:20:31.000 It can come from acid rain. It can come from nitrate, which is a Moff explosive. 00:20:31.000 --> 00:20:34.000 It can come from Rdx. Which is an explosive. 00:20:34.000 --> 00:20:44.000 It can come from fertilizer. It can come from your septic system so sometimes it's challenging to figure out where is your nitrate coming from? 00:20:44.000 --> 00:20:44.000 So in this case they looked at oxygen. Ate, and nitrogen. 00:20:44.000 --> 00:21:05.000 15 these circles. These circles represent the samples that they took in the wells and the soil samples, and the samples that they took fell in the range of the septic source of nitrate. 00:21:05.000 --> 00:21:07.000 The Rdx sauce all the way down here at minus 25 or so. 00:21:07.000 --> 00:21:16.000 So we were pretty sure it didn't come from there in terms of shen acid rain. 00:21:16.000 --> 00:21:25.000 It's unlikely. It's 2020 per mail of 18 oxygen. 00:21:25.000 --> 00:21:30.000 So possibly didn't come from there. Nitrate a mark explosive. 00:21:30.000 --> 00:21:34.000 I think you'd know if you use that at your site. 00:21:34.000 --> 00:21:41.000 So when the nitrate on the goes denitrification which is typical, this is what happens. 00:21:41.000 --> 00:21:47.000 The delta, oxygen gets heavier. It's heavier, and so does it. 00:21:47.000 --> 00:21:54.000 Delta nitrogen. So the samples from the wells were actually following this denitrification trend line. 00:21:54.000 --> 00:21:59.000 So the source in this case was assumed to be from a septic system. 00:21:59.000 --> 00:22:06.000 This shows how you can differentiate where you nitrate is coming from. 00:22:06.000 --> 00:22:08.000 So next, let's talk about Vita. Intrusion. 00:22:07.000 --> 00:22:18.000 Is Ccnpc. Coming from stuff you have in the house, or is it coming from chemicals? 00:22:18.000 --> 00:22:27.000 Underground. So this study was done at 5 different residences to see what was happening. 00:22:27.000 --> 00:22:33.000 So first, one residence, one residents, one. They only did. 00:22:33.000 --> 00:22:39.000 Carbon, 13, isotope analysis, and that was sufficient to tell them where it was coming from. 00:22:39.000 --> 00:23:03.000 Consumer products. This is something that we know. They tend to be in the minus 25 to minus 32, also range the indoor air at the Resident was more around the minus 10, much heavier groundwater near the Resident V varied quite a bit so in this case we knew 00:23:03.000 --> 00:23:09.000 that it was coming from the groundwater, not from the consumer products. 00:23:09.000 --> 00:23:25.000 So in this case, just doing C. 13 was done enough to let us know that our source at this house was the groundwater and not the consumer products and it's hardly likely to see in your house is degrading. 00:23:25.000 --> 00:23:30.000 So in this case we think it came from the groundwater. 00:23:30.000 --> 00:23:35.000 Okay. Let's look at residents 2 and 3. 00:23:35.000 --> 00:23:42.000 Where is our pce coming from here? So in this case the black circle is in the air. 00:23:42.000 --> 00:23:48.000 The X is your soil gas, the groundwater is the open square at Residence 2. 00:23:48.000 --> 00:24:01.000 This is the iotope ratio of the indoor air isotope of ratio of the ground water, which is the similar for chlorine, but different from C. 00:24:01.000 --> 00:24:10.000 13, at residence, too. They also analyze the commercial product that was in the house, and found that the Csi. 00:24:10.000 --> 00:24:11.000 Showed okay, Pce was actually from a chemical that was being stored in the house. 00:24:11.000 --> 00:24:23.000 In this case they needed additional data. The commercial product analysis also provided additional date. 00:24:23.000 --> 00:24:28.000 Let them know. That is where the PC. Was sourced from. 00:24:28.000 --> 00:24:33.000 So then we look at Resident 3. 00:24:33.000 --> 00:24:41.000 That's the indoor air signature, the X is the soil gas signature, the square is the groundwater signature. 00:24:41.000 --> 00:24:48.000 You look at this, the groundwater signature that's quite, quite different from the indoor air and the soil gas. 00:24:48.000 --> 00:24:56.000 So in this case the assumption was made that the Pce came from a commercial product in the home. 00:24:56.000 --> 00:25:04.000 And then for residents 4 and 5 it's getting a little more interesting here and a little little tricky here in the Fourth Resident. 00:25:04.000 --> 00:25:11.000 The, tce. They looked at Cl. 37, and they looked at carbon 13. 00:25:11.000 --> 00:25:18.000 And what they found is that groundwater was discharging to the sewer lies. 00:25:18.000 --> 00:25:28.000 So in this case, Csia said, Okay, the source is the groundwater, and it will, coming from the fact that groundwater was entering the saw lines. DC. 00:25:28.000 --> 00:25:35.000 Would sweep arising into the whole, and then Resident 5 was no, no conclusion could be made. 00:25:35.000 --> 00:25:38.000 There's a lot of data. Nothing really lined up. 00:25:38.000 --> 00:25:44.000 So possibly multiple sources. We're not sure. So I'll move on in the interest of time. 00:25:44.000 --> 00:25:46.000 Just a few more slides here, so in terms of site characterization, we can try to figure out a degradation occurred. 00:25:46.000 --> 00:25:58.000 How much of it has occurred. We talked about the source of different chemicals. 00:25:58.000 --> 00:26:03.000 Have there multiple sources, is it dissolves or non-acre space? 00:26:03.000 --> 00:26:12.000 So let's look a little bit more at how we use Csi and side characterizations how many times have we seen data aware our chemical of concern concentration is decreasing with this and relax. 00:26:12.000 --> 00:26:20.000 Okay, maybe it's degrading. 00:26:20.000 --> 00:26:25.000 But we really can't take just this data to a regulator and say, Hey, my plumes going away? 00:26:25.000 --> 00:26:32.000 Its concentrations are decreasing. So that's why we take additional data. 00:26:32.000 --> 00:26:36.000 In this case we do cover on 13, and you see the common 13 of the Tc. 00:26:36.000 --> 00:26:40.000 Here. It's the same throughout the plume. So this is a clair case of dilution. 00:26:40.000 --> 00:26:52.000 It's simply being the greeting here. So this is gives us an idea. 00:26:52.000 --> 00:26:57.000 What happens, what is happening to this? DC, and then this shows a lab study here. 00:26:57.000 --> 00:27:07.000 This is Mtv aerobic degradation has a very different signature from Anaerobic degradation. 00:27:07.000 --> 00:27:10.000 The black circles are our site data. Can we look at this and definitively say, what's happening? 00:27:10.000 --> 00:27:21.000 I don't think so. So this is why we need some other data to also support Csi A, we need some. 00:27:21.000 --> 00:27:27.000 Chemical data, Geo. Chemical data, microbial data to help us understand what's happening at this site there's been a lot of work done done at the site with conclusions changing over time. 00:27:27.000 --> 00:27:41.000 I'm not sure what the final analysis was, but I know this site has undergone quite a lot of work. 00:27:41.000 --> 00:27:47.000 And then the last. I think this is the last slide on that characterization. 00:27:47.000 --> 00:27:52.000 This study was actually done on eb concentrations were decreasing over time. 00:27:52.000 --> 00:27:58.000 They didn't know the mechanism of the degradation. 00:27:58.000 --> 00:28:06.000 It was an anoxic site. Literature says that Edb can degrade both biologically and abiotically. 00:28:06.000 --> 00:28:11.000 They looked for microphones, no microbes so measure C. 00:28:11.000 --> 00:28:13.000 13. I believe this was a lab study. This was a lab study and measuring. C. 13. 00:28:13.000 --> 00:28:24.000 In the lab study, and what they saw in the biological bottles. 00:28:24.000 --> 00:28:28.000 Not much was happening abiotic degradation, bubbles. 00:28:24.000 --> 00:28:39.000 13. Signature suggesting that Ebb was actually degrading a bioterrorist at this site. 00:28:39.000 --> 00:28:44.000 So you see how Csia can give you some really, we need valuable information here. 00:28:44.000 --> 00:28:50.000 So just a few things to keep in mind as I as I wrap up here. 00:28:50.000 --> 00:28:59.000 So if you do take Csi data, and you see, there's no difference in the ratio between different locations. 00:28:59.000 --> 00:29:02.000 Chances are it's a single source. It's one source. 00:29:02.000 --> 00:29:11.000 Look at some other data to confirm that. But if there's no difference in your ratio, possibly the same source. 00:29:11.000 --> 00:29:19.000 Then, if you look at samples from different locations with different plumes and flow pads have different, isotope, ratio. 00:29:19.000 --> 00:29:25.000 Chances are you have multiple sources at website. 00:29:25.000 --> 00:29:37.000 And if your samples, partitioning into groups, and it really doesn't match your Csm, then you wanna take a second look at your Csm and say, Okay, am I really understanding my site correctly? 00:29:37.000 --> 00:29:44.000 And if most of your samples are isotopically different from each other, you may have had some degradation taking place. 00:29:44.000 --> 00:29:51.000 You may have multiples sources, will review additional additional site, detail so just a few key points. 00:29:51.000 --> 00:29:57.000 I'd like you to take from this presentation. Dsi is a tool. 00:29:57.000 --> 00:30:06.000 It's available out there that it can be used for sauce, identification, and it can be used to determine if degradation is happening at your site. 00:30:06.000 --> 00:30:06.000 However, the isotope ratio varies even from the same manufacturers of sources. 00:30:06.000 --> 00:30:17.000 It varies even by batch, because it's based on it's based on the method of analysis and your raw materials. 00:30:17.000 --> 00:30:29.000 You have to keep that in mind. And Csi works best in a multi-line of evidence, approach with other characterization techniques. 00:30:29.000 --> 00:30:35.000 So I would not recommend it stands alone, use it with other techniques as well. 00:30:35.000 --> 00:30:43.000 And it's better to determine the isotope ratio of more than one element, not just carbon, but more than one element. 00:30:43.000 --> 00:30:46.000 Collect multiple samples in the past what we've been doing. 00:30:46.000 --> 00:30:48.000 We've just been taking. Css. Csi samples, sometimes ones just ring side characterization. 00:30:48.000 --> 00:30:57.000 But it's important, like, how we do chemical analysis to take these Csi samples multiple times. 00:30:57.000 --> 00:31:08.000 So take a few samples along the flow path. First time you go out there in 6 months or so, take the samples again. You know. 00:31:08.000 --> 00:31:14.000 See what's going on. Don't just take it once and expect an answer. 00:31:14.000 --> 00:31:24.000 So in terms of references, I put these references here because if you want more information, these are pretty good as an EPA reference, there's a sort of environmental Wiki page. 00:31:24.000 --> 00:31:24.000 Itrc. Has a document. I was actually on that team, and we prepared that document. 00:31:24.000 --> 00:31:41.000 And most recent, napha actually produced a fact sheet on chemical-based environmental molecular diagnostics, tools, so I would say, these are probably the best references out there. 00:31:41.000 --> 00:31:47.000 Just to get more information on see it. So now I'll open up the floor. 00:31:47.000 --> 00:31:51.000 If somebody has experience with Csi, they wanna share with everyone, or if anyone has a question, I'll see how best I can answer it. 00:31:51.000 --> 00:31:59.000 So thank you. 00:31:59.000 --> 00:32:05.000 Alright! Thank you. Round of applause. 00:32:05.000 --> 00:32:05.000 I'm waiting to see if any hands come up here. 00:32:05.000 --> 00:32:17.000 I do have some that were online so if it's Ok, I'm going to start with the remote questions, Ramona, earlier in your presentation. 00:32:17.000 --> 00:32:24.000 Someone posed this question, why is the Delta mill positive on your nitrate slide? 00:32:24.000 --> 00:32:29.000 So in that case, nitrate, measured would have been heavier than the standard. 00:32:29.000 --> 00:32:37.000 I'm not sure what they used for the standard. In that case, but that just means it was heavier than the standard that was used. 00:32:37.000 --> 00:32:43.000 The standard is assumed to be 0, and your sample is compared to the standard. 00:32:43.000 --> 00:32:52.000 So it was heavier meaning. There was more of the heavy isotope in it. 00:32:52.000 --> 00:33:00.000 Okay? And our next question, did you complete some mass-balance calculations in media samples? 00:33:00.000 --> 00:33:16.000 For example, soil, groundwater, and the vapor phase to adequately characterize the distution and fate of both the tracers and chemical compounds. They then go on to ask, how is the mass balance influenced in the individual sampled media? 00:33:16.000 --> 00:33:21.000 Okay, so, yes, we're always interested in what's going on with the mass balance. 00:33:21.000 --> 00:33:28.000 It doesn't always work out the way we want. We don't always get a good, a good mass balance. 00:33:27.000 --> 00:33:44.000 Intrusion, measuring multiple media on the soil, the water, the air, if you can to help develop that mass balance, I would recommend it. 00:33:44.000 --> 00:33:54.000 It's not perfect, though you very rarely get a good mass balance, because it's so complex. 00:33:54.000 --> 00:33:58.000 Okay. Ian, you have a comment in the room. Yeah, I was curious. 00:33:58.000 --> 00:34:02.000 What commercial laboratories are offering. Csia. 00:34:02.000 --> 00:34:02.000 If you're familiar with any. 00:34:02.000 --> 00:34:07.000 Okay, so there, yeah, there will be out there. I'm just calling names. 00:34:07.000 --> 00:34:11.000 I'm not saying I'm not endorsing them. 00:34:11.000 --> 00:34:18.000 Just so, you know, but they's Microsoft is microbial insights, and I know the University of Washington of Waterloo in Canada. 00:34:18.000 --> 00:34:28.000 They also have now opened an official commercial lab, where they can for Csi. 00:34:28.000 --> 00:34:33.000 So those are the 3 that I know of. 00:34:33.000 --> 00:34:33.000 I heard recently that microbial insights may no longer be offering that. 00:34:33.000 --> 00:34:39.000 So I was looking for other resources. 00:34:39.000 --> 00:34:43.000 Microsoft, and Waterloo like. What do I know? 00:34:43.000 --> 00:34:48.000 Most recent. I've heard of them doing it. 00:34:48.000 --> 00:34:52.000 Thank you. All right, Bobby. I see another question in the room. 00:34:52.000 --> 00:34:57.000 Just, a remote, excellent presentation. That's really good technique to think about. 00:34:57.000 --> 00:35:00.000 My question is regarding the A method that you use and the technique did you use? 00:35:00.000 --> 00:35:12.000 Icp, Gc, mass, Pic, or just Gcm mass, pick, and what kind of analytical error you are looking for in order to make the conclusion. 00:35:12.000 --> 00:35:19.000 Okay, so typically I thought, ratio mass spec, that's typically what's used. 00:35:19.000 --> 00:35:30.000 Gc. Irr, Ms Gcms. Can also be used and in terms of the error around the point 5 per mill, I would say, is within the era. 00:35:30.000 --> 00:35:47.000 So if you see samples 28 minus 28 to minus 26, we would consider that a true difference. If it's minus 28 to minus 28.5, maybe not, because that's within the. 00:35:47.000 --> 00:35:49.000 Just the following question, do you believe I think we're using laser application technique? 00:35:49.000 --> 00:36:04.000 Icpgc mass paper. Do you think this could use legislation, technique or solid samples? 00:36:04.000 --> 00:36:07.000 And you could get the same accuracy. 00:36:07.000 --> 00:36:20.000 I guess if you can extract you can extract your chemical out of you'd have to do an extraction to get it out of there and then inject it into your Gc. 00:36:20.000 --> 00:36:25.000 Yes, you should be able to get good data. 00:36:25.000 --> 00:36:34.000 I think, even with Did you say Icp? And then Gcms. 00:36:34.000 --> 00:36:37.000 Thank you. 00:36:37.000 --> 00:36:37.000 Alright, we did have a couple of other individuals who chimed in with other laboratory services that do. 00:36:37.000 --> 00:36:50.000 Csia. So, Em, if you need some extra names, the audience has been charming in isotope, tracer technology and a few other have come in so I'll be happy to share those. 00:36:50.000 --> 00:37:06.000 We do have another question that came in online. And I'm just going to read it as written used on Source Id for pfast pfoa question. Mark. 00:37:06.000 --> 00:37:21.000 Good question. Not that I know out most recently, last year we were trying to find some label the P-fast to use in lab studies, and they was one place offering it. 00:37:21.000 --> 00:37:27.000 However that life of it was pretty short, but I have not been one attempt. 00:37:27.000 --> 00:37:34.000 Pfas, source, identification.