Organic Geochemistry - Science topic

Dear Harald S Poelchau sir thanks for answering this above question, I'm unable to access the first article (if possible, please send me a pdf version of this article).

In 2nd article, I'm unable to find any relationship between the volatile matter and vitrinite reflectance.

You may use this link:

Hi dear Megan,

You can read this paper and download the one inreference

Gustafsson, Ö., Bucheli, T. D., Kukulska, Z., Andersson, M., Largeau, C., Rouzaud, J. N., ... & Eglinton, T. I. (2001). Evaluation of a protocol for the quantification of black carbon in sediments. Global Biogeochemical Cycles, 15(4), 881-890.

Dear Mr. Mokri,

I, happy to share ASTM D7708 - 14 standard with you. I sure it will help you.

Please find the attached pdf file.

Regards

Alok

Thank you so much. Will check that.

Unyime Umoh

Yes, I am totally agree your comments. As the sampling area is a big shallow urbanized lake, many sources was generally mixed and biodegraded. I have already tried to apply the proxy as your recommend, and I got a higher contribution of terrestrial and sometimes petroleum contribution. But what I am confusing is that the particles have lower C/N ratios and relative low POC/chla (<100 microgram per Litter) as I said in my questions. And actually I am not expecting the higher contribution of terrestrial, because the lake is highly eutrophication, and cyanobacteria bloom (I thought they are main contributors to C17 in my case) is serious issues in this lake. So I am wondering if the alkanes indicators are still robust in my case, since I saw some articles showed the diagenesis effect could cause higher contribution of long chain n-alkanes in sediments, even though the allochthonous inputs is few.

And I am very grateful for your suggestion, I will try to test them. Could you tell me the approximate retention time of these compounds basing my TIC graphs, it will be helpful for quickly locating them.

Yes and no, it all depends on the depth of your question and the scope. If it is a classic source rock evaluation integrated into a larger program that includes petrophysical and basin modelling components , you might get away with it for an initial assesment. However, if your main focus is the holistic evaluation of the source rock potential, you MUST include Organic Petrography (using both transmitted and reflected white light and UV light), as well as sulfur speciation work (the Rock-Eval 7S can now do that and you get differentiation between S2-sulfur and S4 sulfur from that coming from sulfides and sulfates), Pyrolysis-Gas Chromatography (if possible). In addition, if you samples are thermally mature, you need to use a modified pyrolysis program (Shale Play, MHR, Reservoir, etc.), the basic temperature program might not be adequate.

Please see the following article

Best Regards Suresh Kumar Govindarajan

Porosity calculation from images is a hard task. There are some issues:

1) only ex-situ porosity you can determine. you can interpolate the pores inside the material, but not a recommended one. Solution: you can use gas adsorption techniques to get an estimation.

2) Detecting pores is also challenging. If the pores are irregular than complexity arises. I have used Atomic force microscopy images (AFM), where I used height data based images to detect pores.

3) SEM requires vacuum condition to operate. To take image in ambient condition you might take AFM images. I know this is not a big issue, sometimes image taken in ambient condition might provide some extra information.

You can see my paper:@Yacine Mokri

Thank you for your answers! Jai Ghosh Bayan Hussien Steven L. Larson

Dear Ali Gadalla Najem

Thank you for your help

Hi Moamen,

The following links could be useful:

https://www.tdi-bi.com/analytical_services/environmental/NOAA.../TOC.pdf

https://www.researchgate.net/.../How_does_calculate_the_organic_carbon_concentration.

https://www.mhnederlof.nl/srlog.html

Regards!

I agree with Matthieu. Cycling in this context means the movement of elements within soil, from soil to plants as they take up nutrients, to animals who eat the plants, back to soil or into air/water when plants and animals die, , back into plants as they grow etc.. It is a cycle because the elements are continuously moving around in the environment in repeating "cycles". There are some very well-known and well identified cycles such as the carbon cycle (see https://en.wikipedia.org/wiki/Carbon_cycle), or the nitrogen cycle (https://en.wikipedia.org/wiki/Nitrogen_cycle).

Dear Mr. Hamed,

even if English is not my mother tongue I do not see any difference between material, matter, substance and “stuff” as has been underscored by Dr. Towe. Maybe there are more serious linguistic connotations in geosciences which should be subjected to a semantic debate. The important dictionaries used in geosciences do not discuss this issue of matter or material.

We should not do it either and do not create artificially differences and rifts H.G.Dill

Pleased to meet you!

You're welcome @ Pezhman Rasekh

CaO* is the content of CaO incorporated in silicate fraction. McLennan (1993) proposed an indirect method for quantifying CaO content of silicate fraction assuming reasonable values of Ca/Na ratios of silicate material. Procedure for quantification of CaO content (CaO*) of silicate fraction involves subtraction of molar proportion of P2O5 from the molar proportion of total CaO. After subtraction, if the “remaining number of moles” is found to be less than the molar proportion of Na2O, then the “remaining number of moles” is considered as the molar proportion of CaO of silicate fraction. If the “remaining number of moles” is greater than the molar proportion of Na2O, then the molar proportion of Na2O is considered as the molar proportion of CaO of silicate fraction (CaO*).

Most shales are formed in a non-oxygen medium. In the zone of serozarazheniya. This affects all chemical and physical processes of formation and transformation of petroleum matter. We study this in detail on the shales of Tatarstan. This has its own criteria.

Thank you for your comment Yacine Mokri, and your previous comments Mr Bencini and Mr Idan. It shows the problem with this topic, there is a lot of personal believe and interpretation involved, leading to very different schemes. Just comparing the schemes submitted by you both, Bencini & Idan, we see significant differences. So who is right???

And you are fully right, Yacine Mokri, that different palynomorphs show different colours at the same maturation levels. Pollen are different from spores, which are different from algae, or dicocysts or acritarchs. And even within each group we see clear differences, depending on wall thickness, density and thickness of ornament, preservation (chemical & microbial alteration). So you have to use very similar types of palynomorphs to have good colour correlation. And because the kerogen we study is from sedimentary rocks, which are mostly recycled to some degree, you can have similar types of palynomorphs in different colours in one sample, due to recycling of higher mature material in your less mature sample. So you see, it's pretty complex.

Unfortunately also the documenting of our results brings additional uncertainty, because the colour of our photoplates depend on the specific of microscope, magnification, lightning system and so on. Therefore the same sample will show three different pictures in three microscopes. And if you take paper, the colours in ptinted papers are effected by printing, in digital documents colours are effected by your system, programs or the settings of your screen.

Working with Vitrinite reflectance and palynomorph colours for several years now, I realized also an age dependence of palynomorph colours. So stratigraphy is another point making it more complex.

So it's even more complicating. And the dream of a simple TAI chart working for everything is finally gone, I guess. Sorry Cristiana.

On the other hand palynomorph colours are just a fast initial tool to determine maturation on a relative rough scale (immature, low/medium/upper oil or gas) and for this we can ignore a lot of the difficulties above.

As one solution, I would like to encourage you to work with the palynomorph darkness index (PDI) from Goodhue & Clayton, which might be a good way out of the troubles with the previous colour analysis schemes.

cheers

Hartmut

Dear Sir

I think the links below will benefit you in your search

Best Regards

Dear Sir

To get the best answer, read the following papers

The solubility of EPS varies greatly, depending on its composition. Even within a single organism, such as certain Lactobacilli, homopolymers can vary greatly, depending on their structure. For example, Streptococcus spp. produce two types of glucose polymers: water-soluble dextran and water-insoluble mutan, as well as intermediate combination forms of both.

Regarding the pKa and acidity, that also depends on the EPS structure. In the case of neutral polysaccharides, composed of neutral sugars like glucose or mannose, it's not much of an issue. In the instance of acidic polysaccharides like bacterial alginate, it MAY be an issue. However, these usually exist in the salt form at physiological pH, rather than in the protonated, acidic form. The presence of acidic carboxylate groups will definitely affect the buffering capacity and metal-binding capacity of such biofilms. So, yes, it can depend on the functional groups within the EPS.

You can use the LC-NH2 powder to pack into the glass pipette as the NH2 column, it's very easy way to make your own column. And you can download the specific procedure from the Yongsong's lab procedure in Brown University.

Good luck!

prezentácia od luis pedra z uniovi neviem, či pomôže, ale pod obrázkami je väčšinou zdroj a teda možno v tých zdrojoch nájdeš, čo potrebuješ.

Dear Dr. Peng,

I routinely use a cross plot of  PI versus Tmax to identify samples containing migrated (non-indigenous hydrocarbons) - see attached word document.  This cross plot is based on comments from Peters et al (1986) Guidelines for Evaluating Petroleum Source Rock Using Programmed Pyrolysis. AAPG Bull. 70, p. 318-329

The following quotes from that reference are of specific relevance here"Oilbased mud contamination or migrated oil is likely for immature rocks (Tmax less than about 435°0 where PI or Sl/TOC is greater than 0.2 or 0.3, respectively"

"Pyrograms of contaminated or reservoir rocks, such as that from 2,090 ft (637 m) in Table 4 (Figure 13), commonly show an SI peak greater than 2 mg HC/g rock, an anomalously high PI and low Tmax (compared to adjacent samples), and a bimodal S2 peak."

Best Regards,

James Collister

Dear Dr. Censi,

Thanks for your helpful questions.

Best wishes

Mansour

Thank you Razgar

From: https://www.researchgate.net/publication/240430744_Refinement_of_organic_methods_for_kerogen_characterization

"The amorphous kerogen components (amorphinite) are subdivided based upon fluorescence properties into fluoramorphinite (fluorescent) and hebamorphinite (non-fluorescent)."

Probably, the non-fluorescent Hebamorphinite is poor in fluorescent components ("live" hydrocarbons).

Therefore, it may represent "spent" source rock (a former source rock that expelled all possible hydrocarbons after reaching very high thermal maturity ).

Alternatively, a totally immature source rock would also contain no hydrocarbons.

It should be easy to establish, from the geological setting of your samples, if you are dealing with totally immature sediments from a thermal viewpoint, or nearly metamorphosed sediments.

Hi Rasiq,

Prior to adding an answer to your question some questions back. are you considering organic or inorganic geochemical proxies? For what purpose would you want to reconstruct paleoproductivity and on what time scales - e.g. Do you want to see changes over glacial/interglacial cycles to see the monsoon intensity or are you interested in the anthropogenic influence on the environment?

There is a lot of published work - though most of it in the marine environment. These may give you a start - but there are hundreds of papers linking d13C to productivity.

 Kemp A, GSoL Vol 116 1996,

Boyer et al, PPP, 306. 2013,

Goudie & Viles ESR, 113 2012

La Porte et al PPP, 276, 2009.

PPP is probably the best journal to start with some key word searches...

Dear Erik,

The answer is YES. Please read the following publication: 

ARTICLE in BULLETIN DES SOCIETES CHIMIQUES BELGES 88(7‐8):577 - 597 · SEPTEMBER 2010 with 8 READS

DOI: 10.1002/bscb.19790880711

ABSTRACT

In an attempt to improve our knowledge of bimetallic catalysts usually used in reforming we studied three series of catalysts: Pt-Re, Pt-Ir and Ir-Os.For our Pt-Re catalysts, both metals are reduced to the metallic state and a catalytic effect of platinum on the reduction of rhenium oxide has been evidenced. The infrared spectra of carbon monoxide adsorbed on those catalysts have shown that platinum and rhenium interact together, they are probably alloyed.The catalytic activities of those Pt-Re, Pt-Ir and Ir-Os bimetallic catalysts were determined for various organic reactions. The effect of alloying is different for the various reactions, but the activity of the bimetallic catalysts for a given reaction is never the sum of the activities of the two metals separated. Some important synergistic effects were found. Surprisingly, a marked analogy between the curves activity for given reaction versus the composition of the catalysts has been found for the three series Pt-Re, Pt-Ir and Ir-Os. Some interpretations for those observations are discussed.The use of bimetallic catalysts has been a considerable improvement in catalytic reforming [1–8]. Pt-Re [1–4] and Pt-Ir [5–8] are among the most widely used in this area and the catalytic effects of adding metallic promoters to platinum are multiple. Those promoters act by i)changing the initial selectivityii)decreasing the sintering rateiii)decreasing the coking rate during reaction of hydrocarbonand iv)maintaining the initial selectivity despite coke deposition and activity loss.However little is known on the reasons of those effects and many questions are still pending. For example, what is the degree of interaction between the two metals. Even the oxydation state of rhenium is still a matter of controversy.This is why we started a few years ago a study on bimetallic catalysts containing platinum, rhenium, iridium or osmium in collaboration with a group of research of the Institut de Recherches sur la Catalyse of Villeurbanne.The bimetallic catalysts have been characterized by their physico-chemical properties and their catalytic properties for various organic reactions. 1)The investigation of the reduction by hydrogen by means ofi)differential thermal analysisii)thermogravimetryand iii)volumetry2)The study of the metallic phase after reduction by hydrogen-oxygen titration and IR study of CO chemisorbed3)The study of the activity of the catalysts in the following reactions:-dehydrogenation of cyclohexane and 1,1,3-trimethyl-cyclohexane [9]-hydrogenation of benzene-epimerization of 1,2-dimethyl-cyclohexane [10]-hydrogenolysis of cyclopentane and butane [11,12]-benzene-deuterium exchange.

Hoping this will be helpful,

Rafik

Your question takes me back 40 years ago, back to my thesis work on organic geochemistry (1973 !). As I can remember, biosynthesis of natural fatty acids is from Acetyl-CoA and produces even number fatty acids. Green leaves contains large amounts of epicuticular waxes to protect them from heat and water (same for insect pupae such as blowfly). These waxes are long chain aliphatic esters (up to C60 and sometimes above) from long chain even numbered fatty acids and even numbered fatty alcohol. Upon burial, bacterial degradation, ...,fatty acids can be released, and together with natural fatty acids, can be decarboxylated, yielding odd numbered alkanes. Further burial and thermal degradation tends to flatten the difference between odd and even numbered alkanes. I guess that there are numerous papers in the literature that have reported this observation, and it is a characteristic difference between recent and ancient sediments.

Note that long chain waxes are often hidden as they do not elute easily from a GC column, and should be first transesterified and derivatized. As for LC, they show no response under UV detection, only by LC/MS under APCI or ESI.

These are just old souvenirs !

Thanks!

Dear Dr Md. Salah

Actually i am working totally in REE species. The REE (e.g., La) less affected by diagenesis when go down to ground profiling even though the iron is REE transporter.  However regarding the lanthanum - As-DOC or anaerobic  condition in  where intention on the role of humic and fulvic of REE in groundwater system. How far the reactive and conservative behavior between thus metal ions also play important role either in dissolve or solid state be considered. The rebound problem should consider of Mn oxide or coated Mn-Fe-Ox-hydroxide complexation between dissolve and particulate before scavenging to surface sediment until certain level of equilibrium. Again according to your research kindly, please refer:

Johan Schifjf, Emily A. Christenson and Robert H. Byrne 2015, YREE scavenging in seawater:  A new look at an model. Marine Chemistry

Robert H.Byrne and Ki-Hyun Kim, 1990. Rare earth element in seawater. Geochemica et Cosmochimica Acta.

Hein de  Baar and Johan Schijf,1991. Solution chemistry of rare earth element in seawater. Europe Journal of Solid state and inorganic Chemistry.

Regard's

Zolhizir Daud

You can use the Passey method or the CarboLog method. Both methods combine an eletric log and a porosity log (sonic) for calculation. Please take a look for those methods.

these two companies have performed such soil surveys for us.

Did you run the pattern through CrystalSleuth against the RRUFF database ? If you send me a copy of the spectrum data in CSV format I can run it against a RRUFF extract that is both cleaner and more extensive than the one released with CrystalSleuth from the RRUFF website.

Dear Dr El Nady,

Organic Geochemistry in a simple sense is the study of the chemical components of any organic materials that might have decomposed under certain geological conditions/processes to become hydrocarbons (gas, condensate or oil).

Petroleum Geology again in a simple sense is a Geological Setting (usually basins) on a regional scale where it is most likely to generate & accumulate hydrocarbons. There are at least some critical geological factors (source, maturity, migration, reservoir, seal, trap) that one has to asses for any basins if they worth prospecting for.

Both Petroleum Geology & Organic Geochemistry go hand-in-hand if you want to understand the whole petroleum system of a basin.

Regards

shadrach

The type of OM which is derived from aquatic environment is already consist mainly from Algae's ,Bacteria ,these particulate OM have bio polymer and mainly content Carbohydrates , Proteins ,Fats and other pigments and so on ..Already determines S1, S2, and S3, promising to generate oil mainly, other wise Higher plants which the mentioned above biopolymer lacking with it, but rich in Lignin (responsible for keeping the plants standing ,is promising to generate gas only .

Regards

Dear Chin,

Thank you for your question but I have no competence to respond. I am sorry.

All the best,

Nathalie

Dear Professor Connan,

Thankyou for the guidance.

Basin modeling based on the burial thermal history ,and determination of lithology for each formation overburied the source rocks and vitrinite reflectance ,and other agents could enable to setup model to indicate transformation ratio that declare the time and extent of oil generation and increasing of tempreature accordingly .

We have a Thermo iCAP 6300 DV running extracts / digests of soils, rocks, plant and animal tissues, as well as natural waters and experimental solutions. As others have noted, the dual view is a big plus if you are dealing with a wide range of analytes, matrices, or concentrations. I was not involved in the purchase of this instrument but I believe that was the rationale for choosing it.

You will want to consider operating costs including torch lifetime as well as upfront costs. The iCAP eats its torches more rapidly than either of the older instruments I previously used, though their lifetime depends strongly on what matrix we're running. An argon humidifier has helped with this, especially in high dissolved solids and high organic matter matrices (e.g. soil extracts). We have also seen big price increases for high purity N2 and Ar that have put our run costs way up over the last couple of years.

Our instrument is excellent for transition metals and REE at trace levels (mostly ppb), and it is good for metalloids (tens of ppb As and Se in plant / soil digests, probably better if we really spent some time on it). Even alkaline earths are good. For alkalis... I wish we had an AA for the soil fertility people to use, because K is just awful.

Good luck!

Leslie