Environmental Geochemistry - Science topic

Use R-package : psych

Another source could be oxidation of the methane (both biogenic and thermogenic). But even the 13C depleted thermogenic methane requires some biologically produced organic matter as starting materials. Sorry for this kind of loose answer. It would be great if you restructure/rephrase the question in more specific way.

Mohsen,

You are not going to infer much about paleoclimates based on geochem data from hydrocarbon reservoirs. The report you get from a lab such as Isotech will include concentrations of fixed gases (He, Ar, CO2, etc) and the C1-C6+ hydrocarbons, but there is nothing in the fixed gases that can be correlated to specifically to paleoclimates ... at least, I haven't seen anything. Many of the gases are mantle-derived. As such, their occurrences and concentrations are not related to atmospheric/climatic factors of the distant past. The matter is much different, however, if you consider geochem data from aquifer systems, specifically dO-18 and dD, the abundances of which are related to temperatures of condensation, sources of moisture, etc. You should look into the large body of literature compiled by the researchers whose works have been published by the Isotope Hydrology Program of the International Atomic Energy Agency. There is enough material there to keep you busy for a very long time.

Best of luck,

BK Darling

MDPI journals, 100s of them now, largely fall into the "predatory" journal category, promising editors of special issues that they do not have to deal with editing, since the journal does this. They do not have technical staff, just those who use an algorithm to choose reviewers and ask for a quick reply, then return these quickly to the author and accept whatever the author returns. A colleague reviewed one paper and requested major revisions; she saw the paper published a week later, none of her comments incorporated. This publisher is in business to publish lots of papers and make money on OA fees from most of them. Do your science a favor, and submit manuscripts to journals with serious reviewers and editors that will improve the quality of your research and the published papers.

You can get ASTER images for Nigeria and any part of the world, from the USGS (United States Geological Survey) Earth Explorer website.

I have attached a manual which I developed for my research students as guide to assessing satellite imageries .Please see attached copy. I hope this would be very helpful to you.

I have reported ratios (for plants, soils, porewater nutrients) using either molar or mass ratios, with the choice depending on where I was publishing and what I was doing with the data. If you are reporting the ratios as simple descriptors of the peat and soil scientists generally use mass ratios, go ahead and do that too. If you are comparing plant and soil ratios to assess relative nutrient limitation, I’ll suggest that it doesn’t really matter as long as you use the same mass or molar units for both plants and soil (although, as John L. Stoddard pointed out, there is a compelling argument for using molar ratios here). If you are specifically interested in stoichiometry (e.g., is there enough N and P to make a specific biogeochemical reaction happen), then molar ratios probably make the most sense.

Whatever you choose, please be sure to clearly report your units. There’s nothing worse than seeing ratios and not knowing if they are mass or molar ratios; numbers are pretty useless without units.

Ashok - H2O2 is used to remove organic matter from sediments - not carbonates. If you are trying to remove carbonates, but wish to leave any clay minerals unaffected, you should use a buffered sodium acetate/acetic acid solution (pH 5.3). If you aren't concerned about the clay minerals, dilute HCl would be fine. E-mail me if you would like the method.

A. Mannan Rouhani following document from USEPA should help you:

https://nepis.epa.gov/Exe/ZyPDF.cgi/2000Y544.PDF?Dockey=2000Y544.PDF

Also check this paper

https://www.omicsonline.org/open-access/determination-of-heavy-metals-in-blood-urine-and-water-samples-2155-9872.1000217.php?aid=33329

By studying the TIME FACTOR of soil genesis. There are factors that accelerate and those that retard soil profile development. Investigation of resistant and non-resistant parent materials can also give insights on past pedogenic activities.

Excellent question and answers, according to our team study in Iran: lead in water pipes , traffic intensity , residential wastes , vehicles and urban industries !

Please kindly see the attached article!

Terrific, now we know you are dealing with water wells and not monitoring wells. Interesting, your findings are the exception not the rule. Most water well samples collected over large periods show large variations in water composition due to vertical aquifer mixing dynamics arising from poor well construction practices. Accordingly, I will assume that the study wells in your region are reliably tapping a single confined aquifer. I will also assume that one of your central goals is to map chemical groundwater evolution from recharge to discharge over a substantial area. That being the case, mapping mean values for selected parameters may appropriate. You should still first test for normality and make the appropriate transformations as needed. I would first test and compare trends in conservative vs. reactive parameters (eg. chloride vs bicarbonate, or stable isotopes of water vs. stable isotopes of DIC). If you have sufficient temporal data from individual sites, you may find that measurements of variance quite instructive. These are the simplest parameters to examine first before continuing to more complicated factor/cluster type analyses. While you are at it, take a look at the work of Craig Bethke, Joseph Toth, Francis Chapelle and Derek Loveley for different approaches to examining regional GW transport in confined aquifers.

Dear Dimitry,

You may be interested in Chaboussou, Sante des Plantes, une revolutions agronomique, (1985) translated as Healthy Crops, A New agricultural Revolution. (2004). It describes how agrochemicals cause the proliferation of pests and diseases. We are starting a new project to bring this up to date and confirm/or deny the ideas. I would be happy to cooperate.

Best wishes, Ulrich

Dear Mohammad Javad Navid Nematollahi

I am adding some ideas to achieving your complicated target.

If you add some persistence organic compound compound to the environment, fraction is move to the water table by leaching. this potential and can be estimated using Kd (Soil:water) and you can proved by the laboratory and field experiments. you can incorporation impact of organic matter for the partition using Koc values. Also, you can predicted fraction transported to offsite by erosion and runoff by a calibrated model and can be proved by field experiments.

I have attached one resorption study, and model study to understand my idea.

Piyal

Use pattern of pesticides and their predicted mobility into shallow groundwater and surface water bodies of paddy lands in Mahaweli river basin in Sri Lanka

Sorption of Carbofuran and Diuron Pesticides in 43 Tropical Soils of Sri Lanka

CIA = {Al2O3 / (Al2O3 + CaO* + Na2O + K2O)} x 100

PIA = {(Al2O3 – K2O) / ((Al2O3 - K2O) + CaO* + Na2O)} x 100

CIW = {Al2O3 / (Al2O3 + CaO* + Na2O)} x 100

CIW´ = {Al2O3 / (Al2O3 + Na2O)} x 100

In the above equations the major oxides are expressed in molar propotions and 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*).

@ Ashok Shaw

CIA = {Al2O3 / (Al2O3 + CaO* + Na2O + K2O)} x 100

PIA = {(Al2O3 – K2O) / ((Al2O3 - K2O) + CaO* + Na2O)} x 100

CIW = {Al2O3 / (Al2O3 + CaO* + Na2O)} x 100

CIW´ = {Al2O3 / (Al2O3 + Na2O)} x 100

In the above equations the major oxides are expressed in molar propotions and 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*).

@ Jhedy Amores

There are two main sources of sulfate to the groundwaters of the Bengal Basin. 1] brackish connate water - estuarine water trapped in the sediments as they were laid down and now preserved in odd patches where later freshwater flushing has been poor. This is typically found at depths > 50 m. 2] Septage. That is, water leaking from pit latrines (villages) and leaking sewers (towns). As most groundwaters are anoxic, sulfate has been removed (or its concentration lessened) from much of the deeper groundwater by sulfate-reduction. See McArthur et al. Waste-water impacts on groundwater: Cl/Br ratios and implications for arsenic pollution of groundwater in the Bengal Basin and Red River Basin, Vietnam. STOTEN 437 (2012) 390–402.

Dear Sir

I think the links below will benefit you in your search

Best Regards

Thanks @Osama Rahil, these papers look interesting, and I'll read them carefully

As John M McArthur has pointed out, you need to ascertain how your water samples have been analysed. Irrespective of the instrumental method (isotope ratio mass spectrometry or cavity ring-down laser spectrometry) it is important to find out of sample d2H and d18O values were scale normalized to VSMOW on the basis of contemporaneously analysed reference water VSMOW and SLAP (or VSMOW2 and SLAP2).

Another crucial point is sample storage. Samples should be sterile (e.g. by sterile filtration) and stored cold (not frozen) in hermetically sealed glass vials (e.g. crimp-sealed) that are fully filled (no void headspace).

Once you are satisfied your sample data are artefact-free, you can begin to consider explanations for your observations. Processes such as evaporation (and condensation) are associated with isotopic fractionation. Associated isotopic fractionation factors are larger for hydrogen than they are for oxygen. For example, equilibrium fractionation factors for precipitation (condensation) of water at 25°C are 1.0793 and 1.00938 for 2H and 18O respectively. Isotopic fractionation associated with precipitation depends on temperature but is also influenced by amount effects (e.g. massive cloud burst).

A good (and free) resource on this subject of water(s) and stable isotopes can be found in the website of the IAEA.

Hello dear Nabil,

tank you for your quik answer!

I respect your opinion, all journals édirors around the world say the same thing!

and I understand it very well, considering your position in this Journal and in in this conference,

for the acceptance I do not generalize but I know works with errors of beginner, and with a english of google translation.

So by respect to the authors, I do not want to mention name or works published in this journal

  .

 must we accept criticism to improve and advance?

   cordially

Hassan IBOUH

Dear Mr. Morad,

such chemical indices are attractive to those who do not know the side effects and cast aside other processes leading to similar datasets. The ratios pretend to be all-embracing if you ignore the "small print". In my opinion they should be used with a stark warning and always supported by other methods from different geoscientic disciplines such as geology, mineralogy and shallow geophysics.

Best regards

H.G.Dill

Once you get a geochemical set of data, you may use the following indices. But, bear in mind they 1) are all indicative and may not always represent the composition.

1) Enrichment factor( Ergin et al. 1991)

2) contamination factor classification (Pekey et al., 2004)

3) Pollution Load Index (PLI) (Tomlinson et al., 1980)

4) Index of Geo accumulation proposed by Muller (1979)

Check with ERL limits

Since you are interested in last 100 years, look at radionuclides 210Pb, 137Cs, 7Be... for dating as well as to see if any mixing takes place. The estuarine areas are prone to intense sediment mixing and removal from tidal forcing, so may not be ideal sites for studying the chronology of human impacts.

Always analyse refractory elements (such as Al,Ti..) which will help you to assess non-crustal sources.

If you wish to see bioavailable fraction, you may carry out sequential extraction studies.

Good luck

Thanks Drs. Ayub and James for your concern

It depends on the nature of the copper mineralisation in the particular area. REE will be more enriched in some types than other types of copper mineralisation (different genetic processes produce copper deposits with differing element associations). However, in general REE are not greatly enriched in most Cu mineralisation (however REE can be quite enriched in some IOCG type copper deposits, e.g. in the minera; bastnaesite in Olympic Dam ore deposit, South Australia). Likewise I think REE may be enriched in the Palabora (South Africa) carbonatite copper deposit. It also depends on what you mean by enriched - it will have a different meaning to you compared with an economic geologist (the latter will commonly be more interested in it if it is an economic by-product, e.g. I don't think it is recovered commercially from ore at Olympic Dam). So your question needs to be more specific.

Both tests relate the mean difference to the variance (variability of measurements) (and to the sample size). The z-test assumes that the variance is known, whereas the t-test does not make this assumption.

Usually one does not know the variance, so one needs to estimate it from the available data. If there is a lot of data available (large sample size), this estimate will be very precise and one can take this estimate as "essentially known". The test statistic calculated from your data will then have a standard normal distribution under the null hypothesis, which is used to calculate the significance of your data. Because the quantiles of the standard normal distribution are often denoted by "z", this test is called "z-test".

If the sample size is not so large, the estimate of the variance is uncertain. For small samples (n<10, say), this uncertainty is quite large. So we only have a rough, uncertain guess what the variance is. If we correctly propagate this uncertainty into the probability model, we find that the distribution of the test statistic is a t-distribution, and the test is called "t-test".*

You will find that the results ("p-values") of these two tests are very similar for large samples. For small samples, the p-values of the t-test will be larger than those from the z-test.

The t-test is always the "more correct" test, and the z-test was only used in ancient times because the normal distribution but not the t-distribution was tabulated in books. Today, as we all use computers, there is no need to use z-tests at all. However, it is not wrong to use the z-test for large samples, because there it really makes no difference.

---

* the t-distribution is a family of distributions. The shape depends on the sample size used to estimate the variance. The larger the sample size, the more does the t-distribution approximate the standard normal distribution.

Here goes some relevant work..

Abstract; To determine the extent of metal association in natural iron oxides, a combination of XRD and chemical selective dissolution techniques was applied to four samples from laterites developed on peridotites in East Africa. The reagents used were dithionite-citrate-bicarbonate (DCB), citrate-bicarbonate (CB), hydroxylamine hydrochloride (HH), and oxalic acid-oxalate (Tamm). From the results obtained, it appears that: (1) the difference DCB minus CB is a better estimator of the metal fraction in Fe oxides than the difference DCB minus oxalic acid-oxalate, especially in presence of gibbsite; (2) the use of HH allows to be distinguished the specific contribution of Mn oxide; and (3) geochemical models for goethite must provide for the existence of ternary solid solutions (Fe, Al, Cr).With regard to the geochemical properties of the elements, it can be concluded that: (1) Cr substitutes for Fe in the same proportions in goethite, hematite, and maghemite; (2) in contrast, A1 substitutes largely for Fe in goethite, little in hematite, and not at all in maghemite; (3) Mn substitutes partly for Fe, but forms discrete phases when total Mn content is high; (4) Ti substitutes for Fe in hematite, but not in goethite; (5) the major Cu-bearing phase is a spinel; and (6) Ni is closely associated with goethite and not with Mn oxides and spinel.

Abstract—Geochemical and mineralogical investigations, including measurements of major and trace elements, Sr isotope ratios, and 238U-234U-230Th activity ratios, were made on an old African laterite to reconstruct its formation steps and assess recent chemical mobilization. The present data support a scenario of discontinuous formation for the laterite, with different bedrock weathering conditions during the formation of each unit, rather than a scenario of continuous formation. Absolute accumulation of Fe, U, and lanthanides in the uppermost ferruginous unit suggests an autochthonous origin of this iron cap by leaching of an older overlying profile. Present chemical distributions of lanthanides, as well as of Rb, K, Ba, and Sr, within the profile cannot be linked to the mineralogical distribution of both relictual primary and authigenic secondary phases.  Complementary lanthanide patterns indicate that these elements were primarily accumulated in the uppermost ferruginous unit before further remobilization and accumulation in the underlying horizons. These redistribution processes may be related to the chemical instability of the ferruginous cap. The 238U-234U-230Th disequilibria indicate that recent U mobilization occurs in the whole profile and that, as for lanthanides, there is a vertical redistribution of U from the uppermost ferruginous unit to the underlying horizons. Moreover, these data show that both U losses and gains exist at each level of the profile. A simple modeling of this double U mobilization process is proposed to interpret the 238U-234U-230Th data. Differences in the mobilization and fractionation intensities of the U input and removal processes can account for the two evolution trends, whichdistinguish the ferruginous unit from the underlying ones. Furthermore, on the basis of this modeling, the profile appears to be in a transient state because of recent changes in the U mobilization conditions, whichcould correspond to major Pleistocene climatic variations. PDF enclosed for further reading...

Yes there is a strong relation.For example, concentration of trace elements emerged from the net stock of parent material and other related soil forming processes..

Iron oxides, iron hydroxides, and iron oxy-hydoxides can all be those colors you describe, as well as they are some of the most common. Depending on the oxidation state and crystal arrangement colors can vary from silver to brown to red to orange to yellow. These minerals include things such as the minerals hematite, goethite, and limonite. Common mineral associations can be in the sulfur realm of things, with elements such as pyrite, which is iron sulfide, and other sulfate-reducing mineralizations.

Hello Dr Latha,

I presume from what you described that you have a U-Pb TIMS lab capable of low blank (sub pg common Pb), single zircon work and supported by decent mineral separation facilities and zircon prep.  The issue to consider with fracturing and deformation of the host rocks is mainly lead loss from zircon surface domains and your ability to remove those by say chemical abrasion, which post dates my experience with air abrasion.   An additional problem in your case, distinguishing the ages of basement and intrusive granitoids, is inheritance.   I cannot say much about the Rb-Sr systematics from limited experience except to say I have seem protolith ages preserved in domains within granulite facies gneisses.

Where I would start is to classify the granitoids by composition and in particular I vs S type.  With I type you might also find titantite, which would help confirm lower end ages and with S type, monazite or maybe xenotime, also useful for direct igneous crystallization ages, metamorphic ages and major hydrothermal events.  S type granitoids are more susceptible to zircon inheritance although this has to be suspected in any case.   I would also look out for clastic sedimentary rocks in the basement as sources of older detrital zircon and the proximity of both basement and later granitoids. Cathodoluminescence  may help with 

You mentioned that the zircons are very scarce so that is another reason to look for monazite or titanite.  However, you should also check your mineral separation facilities if you suspect that you are getting low recoveries of zircon.  Smaller zircons can be washed out in the light fraction on a Wilfley table if it is not operating at the right speed.  Or you might be losing them in inefficient magnetite separations if you are dealing with e.g. gabbros and have a lot of magnetite or a propylitically altered rock and have a lot of pyrite.   On the other hand a scarcity of zircons is not a reason to consider the rocks unsuitable for U-Pb dating.  You may only need a few zircon grains.

The problem in your situation also depends on the age, and age difference of the basement and intrusive, mineralized granitoids and therefore the precision you need to distinguish them.  If they are both Archean you may be fine with just the zircons so long as you do not have significant lead loss events.  With younger .e.g. Mesozoic granitoids I would back up the zircons with monazite or titanite.  

thanks to Dr. Prasad sir and  all for give a detailed explanation about seasonal concentration changes in groundwater.  

Mohamed:

You are an expert in the field of organic geochemistry applications in Petroleum Exploration. What is the purpose of posing this question?

Best

Syed

HCl is by far the easiest method if this acid does not alter other mineral phases such as clay minerals. You can also try to use warm formic, acetic or citric acid I presume.  

An Fe value less than zero is clearly an artefact, but the problem remains.  Once you thaw and subsample for anions why not acidify the solution to dissolve the Fe, measure it  and adjust for the volume removed?

Eh does not correspond well (sometimes) to the concen­tration of the dissolved oxygen and such a situation is given in the literature [Rose S., Long A. 1988].

Rose S., Long A., 1988. Monitoring Dissolved Oxygen in Ground Water: Some Basic Consider­ations, Groundwater Monitoring & Remediation, Vol. 8, Issue 1, 93–97.

Dear James: A little correction, I quote....To do this simply divide the atomic weight of Fe (55.85) by the "atomic weight" of FeO ....wanted to say " molecular weight or formula weight" FeO.

Regards

You didn't indicate how Ca was extracted, e.g. 'exchangeable' or total.  The dunes may well contain shells or shell fragments.  In the lab this CaCO3 will supply Ca into salt solutions such as NH4Cl, unless the pH is 8.5 and the solution is alcoholic.  

Dear Mrs/Mr. De,

Your questions are strongly differing from each other although they have one thing in common, organic matter.

As to your question 1:

There are sapropelitic shales or black shales reflecting a fully euxinic redox regime, the equivalent sediments with a lesser reducing regime may be called gyttia or grey shales.

As to your question 2:

There is a link between organic rich shales and U, because tetravalent U becomes fixed, whereas under more oxidizing conditions U in its hexavalent state is very mobile. U deposits are encountered in the black shales. Due to the high U content, these black shales are also called "hot shales" . High gamma read-outs in wireline logs as such stand for euxinic conditions, high U contents and high TOC (total organic carbon). There is a direct correlation between these chemical and radio-physical components. Please take care. You do not measure U but U equivalents re-calculated from Bi-214. Uranium U-238 emits alpha ray mainly. Thorium is rather immobile, exists only in its tetravalent state and does not respond to these redox changes and is normally transported in heavy minerals such as xenotime, zircon or monazite which do not come to rest in argillaceous but arenaceous sediments

In the attached file the chemical changes are illustrated for black and gray shales being enriched in U.

Best regards

H.G.Dill

It depends on the parameter you would like to measure.

For organic matter i prefer NIRS than IR because it behaves like a physical filter to produce a fingerprint of soil organic matter. I have no experience with Raman

In the NIRSqual project, the approach is qualitative. We compare the fingerprint of soil organic matter we know (from well described ecosystem), compiled in a referential, with soil organic matter we would like to know better (from deep horizon or palaeosoil).

If you are interested to compare your palaeosoil with our NIRSqual referential, please contact me by email or check Ertlen et al. 2010 EJSS.

Best regards

this is not an easy question. As a basic approach the comparison with the Earth Crust Abundance values is quite correct.  I also would recommend comparing with average shale values; the values are, by good reasons, generally in the range of the upper crust. You may find tabulated values in the internet,  e.g. at Yuan-Hui Li (author); A Compendium of Geochemistry: From Solar Nebula to the Human Brain; Table VI-5a.

The main problem is the question of sample grain size you are using and the digestion method. A common recommendation to find background values is the use of fine grain sediments, meaning < 2 mm grain size. However, this range of grain size may contain a lot of sand fraction, which in river sediments generally consists of quartz. Due to transport mechanisms there is a general shift to quartz enrichment in river sediments. The more quartz grains in the sample the less will be the metal concentration, and you cannot compare with average values from literature. So, for sampling you should prefer backwater situations in Feni River or sections with slow moving water where you will find fine grained sediment (< 63 µm); or you have to sieve the material. You also should keep in mind that literature values rely on total digestion. So, with only few exceptions, you also have to do total digestion prior to analysis (e.g. digestion by HF, which is a really awkward job).  Some metals will be easily extracted nearly to total by aqua regia digestion, like Pb, Zn, Cd. These element concentrations can be compared to literature. An additional question is whether a comparison to literature values is really helpful when looking for enrichment of metals. A better proposal is comparison to local background values. For this you have to find out stream sediments from uncontaminated sections in your region, possibly rivers with a high catchment area. With some effort uncontaminated sediments can also be found in the lower part of sediment cores from bayous.

Possibly a look to our sediment surveys on Chilika Lake (India) or Elbe bayou sediments (Germany), both in Research Gate, will give you additional ideas, e.g. on the question of availability of heavy metals.

Good luck and kind regards

D. Zachmann

Neither of your analytical techniques would be suitable to tell you whether you have ferric or ferrous iron in your sediments. XRF determines only total Fe - to see if you have either ferrous or ferric iron you need to carry out XAS. XRD identifies a mineral phase - do you know wich mineral is present? Only with the identification of the mineral you can tackle that question. Because there are many possible ferric oxides, which all have different stabilities.

Some river sections can be either gaining (groundwater discharge) or losing (groundwater recharge, infiltration). The composition of groundwater discharge will vary depending on fluid residence times in the aquifer from recharge to discharge. Recharging groundwater is likely to change composition along the flow line from Ca-Mg HCO3  and Ca-SO4 type fluids (in more arid environments) to NaSO4 type fluids (typical in alluvial aquifers) and then to Na-HCO3 and Na-Cl type fluids. These hydrochemical changes are primarily governed by bacteria, cation exchange, junction potential type reactions that occur as aquifer water changes confinement from unconfined, to semi-confined, and finally confined conditions.  Sulfate at recharge most commonly originates from weathered shales and coals containing pyrite. Sulfate reducing bacteria living in aquifer matrix will gradually consume sulfate along the flow line of in semi-confined aquifers until it is exhausted.  In most basins, sulfate will not be detectable beyond a distance from recharge of a few kilometers or less than 1/2 to 1 km at depth.  So, you may be seeing discharge of water into the river from semi-confined aquifers.  By doing mass balance calculations (using milliequivalents in solution) you should be able to differentiate whether the sulfate discharge is derived from unconfined (Ca-SO4 type fluids) or semi-confined (Na-SO4) type fluids.  Your studies can be supplemented with baseflow analytical methods to help identify zones of discharge.  Here are some useful review articles that will help your understanding.

Sophocleous, M., 2002, Interactions between groundwater and surface water: the state of the science: Hydrogeology Journal, v. 10, p. 52–67, doi: 10.1007/s10040-001-0170-8.

Winter, T.C., 1999, Relation of streams, lakes, and wetlands to groundwater flow systems: Hydrogeology Journal, v. 7, p. 28–45.

Potter, K.W., 2001, A simple method for estimating baseflow at ungaged locations: Journal of the American Water Resources Association, v. 37, p. 177–184, doi: 10.1111/j.1752-1688.2001.tb05484.x.

Smakhtin, V.U., 2001, Low flow hydrology: a review: Journal of Hydrology, v. 240, p. 147–186.

In addition,  you can check out the following articles

1, Similar V/Sc systematics in MORB and arc basalts: implications for the oxygen fugacities of their mantle source regions

CA Lee, WP Leeman, D Canil, ZXA Li - Journal of Petrology, 2005

2, Water and the oxidation state of subduction zone magmas

KA Kelley, E Cottrell - Science, 2009

3, Fluid processes in subduction zones

SM Peacock - Science, 1990.

The described conditions (relatively high TOC, very low S1, low S2 and S3) indicate spent and stripped source rock, i.e. a rock that originally was very rich in TOC, but excessive maturity generated all the hydrocarbons that could be generated from that rock, and such hydrocarbons left the rock altogether, leaving behind only residual, cocked carbon, unable to generate more hydrocarbons but still counting as Organic Carbon. Such rocks would be black, but are not source rock. They are former source rock. You could check the rock maturity indicators (vitrinite reflectance for post-Devonian rocks, other thermal maturity indexes including illite crystallinity).

See for example http://geomuseu.ist.utl.pt/IGR2012/Petroleum%20Geochemistry%20/basic_petroleum.pdf

Interesting question . deep saline acquifers are considered an effective option for carbon sequestration due to their wide distribution  and proximity to emitting source .deep saline acquifers are present in dfferent  geological formations  as revealed by different exploratory drillings  for delineation of deep acquifer zones.

Source-Sink matching for large concentrated CO2 sources in India indicates one very high priority target, a fertilizer plant in the city of Narmadanagar, Bharuch District, Gujarat Province, India, that is <20 km from old oil and gas fields in the Cambay Basin. Two pure CO2 sources are <20 km from deep saline aquifers and one is <20 km from a coal field. source ; Trans.Nonferrous Met. Soc. China. 21(2011) s494-s498.

Please have a look at this link also.

Best of luck with your research, Ambika.

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

Pezhman:

This link would offer some insights:

Best

Syed

Dear Prof. Selvarajah,

Thank you very much. I learn a lot from your advice.

Happy New Year! 

Jiawei 

I CSC sono sparsi poi nei vari pareri ISS, citati poi in decreti specifici

es: parere ISS 23/06/2015-0018668 per PFAS nei suoli Veneti (non agricoli) PFOA-Suoli ad uso verde /residenziale CSC: 0,5 mg/kg

PFOA-Suoli ad uso industriale/commerciale CSC: 5 mg/kg

oppure in Dm Ambiente 12 febbraio 2015, n. 31

Regolamento recante criteri semplificati per la caratterizzazione, messa in sicurezza e bonifica dei punti vendita carburanti, sono citati CSC: Il limite proposto da Iss per MTBE ed ETBE nei suoli verde pubblico e residenziali è 10 mg/kg ss e per i suoli industriali è 250 mg/kg ss (Parere del 2001 n. 57058 IA/12).

** Il limite proposto da Iss per piombo tetraetile nei suoli verde pubblico e residenziali e' 0.01 mg/kg ss e nei suoli industriali è 0.068 mg/kg ss (Parere del 17 dicembre 2002 n. 49759 IA.12).

Dr. George E. Mustoe - Yes,  you have understood my question.

The last sentence of your answer is very important - the role of local environmental conditions in the chemistry of groundwater. The paper you have attached is useful to understand the bacterial activities in the concentration of Mn and Fe. Thanks

Good look in your interesting  research

Julio

You're welcome dear ahmed.

Thank-you Dr Igwe for taking the time to answer this question. While I do understand the need for this type of normalization procedure to harmonize models of sorption derived using different underlying assumptions of surface site density, my problem relates to that it does not seem to work for the surface protonation reactions. The change in delta_pKa implicit in the pKa normalization procedure fundamentally changes the shape of the sorption edge so that a match is not possible, irrespective of the specific surface area or fluid volume/sorbent mass ratio used in the calculation. This, at least appears to be the case when making forward calculations of models described in the literature at different site densities using PhreeqC, which I have now also replicated in VMinteq so it doesn't seem to be a code related issue. Basically, normalization only seems to "work" if it is applied only to the solute binding reactions and not the surface charging (protonation) model. This is at odds with the NEA sorption project recommendations (& the analyses by Kulik, Sverjensky, and others), thus my confusion.

For Fe2+ in solution it is better to try Volumetric analysis and the accuracy of the procedure can be checked by standard solution which is available in market. However ICP-MS is also a alternative.

Mr. Sangsefidi

Ion exchange usually yields secondary calcite during Na-activation of bentonites (smectite rich clays) at industrial scale. The same process may easily occur in nature when Na-rich pore waters flow through Ca-bentonites in saline/alkaline environments. Similarly ion exchange between smectites and zeolites may retain K in the system which during diagenesis may facilitate illitization (see the attached paper). On the other hand one should not confuse ion exchange with specific adsorption due to fundamental differences (stoichiometric vs non-stoiciometric process).

On the other hand, multi-valence cations such as REE do not easily exchange in clay minerals, but may be specifically adsorbed on the clay edges at non-permanent charge sites especially at relatively low pH below the pzc of the edges. Bearing in mind that REE are usually bound in trace heavy minerals, sometimes reported to have formed diagenetically by authigenic processes (e.g. monazite-see the attached paper), it is expected that specific adsorption of REE of clay minerals may restrain authigenesis of such REE minerals.

Regards

G. E. Christidis

Hi there, it can be useful for you:

Bauxite is composed of alumina, silica, iron, titania etc constitutents and mineralogically it contains gibbsite, boehmite. diaspore, kaolinite, quartz, hematite etc minerals. During calcination /thermal treatment at various temperature and time, transformation of minerals/ change in phase occurs. may be the reason for colouration 

1. Introduction to Geochemistry Principles and Applications by Kula C. Misra

It goes even beyond: Nitrate adsorbed to nano may be adsorbed to soil because nano adsorbs to soil. I know just one code capable of modelling co-transport and co-sorption. (You may consult: Totsche K.U., Knabner P. & Kögel-Knabner I. 1996. The modelling of reactive solute transport with sorption to mobile and immobile sorbents - Part II: Model discussion and numerical simulation. Water Resour. Res. 32, 1623-1632.). Kai Totsche is a Professor at Jena University in Germany

Your only practical choice is to look for what you require from mineral dealers, or collect your own minerals, but the latter is a challenge if the minerals are rare.  And when you obtain what you need you will typically have to check the purity yourself, usually by some combination of say XRD and chemical analysis.  Unfortunately, this is often the only practical solution.  Checking what you have is even prudent when you buy  'minerals' from chemical suppliers, as often they can be mixtures rather than pure phases.

Part of your understanding must come from watershed analysis, evaluating land use, sediment sources and sediment sinks (such as dams, low gradient sections).  Sediment movement can be episodic, but if high energy monsoons tend to erode more than aggrade, that suggests the supply of sediment becomes limited, and the channel materials with increased velocities are able to adjust and degrade to pass the higher flows.  If the braided system strongly stabilizes (anastomozed) with roots extending into channel, adjustments would be less than one would expect.  In an aggrading system, you might be able to carefully balance sand mining, so a more normal main channel system that will hold bankfull flow can be maintained.  The problem with braided systems may include riparian tree burial and mortality, able the unpredictable channel adjustments as the multiple channels are unable to sustain enough stream power to pass sediment or water efficiently.  But during monsoon, as mentioned, the remnant main channel system that has aggraded in past, may reestablish due to the increased flow velocity, rapidly eroding the channel (evulve something like a gully response), but during periods of lesser flows, the velocity is insufficient to pass sediment.  There may be measures to apply that might limit the degree of aggradation/degradation fluctuations if that is your intent, such as cross vanes or j hooks to reduce bank stress and provide grade and gradient control.  The ability to assess conditions and prescribe treatments is not easily accomplished through the stardard courses of my college days.  I still feel that the Rosgen training is best to help understanding, but may not be affordable or practical for you.  Rosgen did include a chapter in the USDA-NRCS Engineering Handbook, Part 650 on stream restoration that is on the internet.  Even with basic information, I would suggest you partner or interact with experienced hydrologist, soil scientist and possibly civil engineer that is used to going beyond the typical structural solutions.

"Accelerating redox" can involve either oxidation or reduction, so the contributing factors can be rather different depending on the direction of the change.  As noted in previous replies, water saturation can be an important factor, and it is in turn related to exposure of the soil to atmospheric oxygen. As Anicet Beauvais noted, other important factors include degradation of organic matter, and possible presence of inorganic elements like S, Mn, and Fe. I think it is important to note that for all these materials, redox reactions are usually related to microbial activity. For these processes, the electron transfers that occur during redox changes may me related to enzymatic processes, so that oxidation and reduction may occur in environments that lack the chemical extremes (eg., high or low pH) that are found  in envirrnments where redox reactions are the result of a  purely inorganic process . Examples would be  situations like industrial pollution, or acid mine drainage. For more typical soil environments, I suspect that water saturation and presence of organic matter are the most important factors. I'm attaching a reprint of an example of microbial redox processes that involve Fe, Mn.

Best wishes,George

Yes, these three point are the ones defining some direction, a "trend". The rest of points are just a "cloud". At what probability (alpha) is your correlation significant?

It's difficult to reach any conclusion just by looking at your data, but it looks like if your data violates a fundamental principle because your distributions "do not look" normal from what I can see, just from "eyeballing". If so, all your R2 calculations would be wrong.

If you think the three points are in fact valid results as those in the larger cluster, try transforming your total non-normal datasets using Box-Cox transformation, and then test again your regressions

It's a shame not interest isotope 13C values of CO2 and CH4 to confirm origin the cause "degradation M.O". In this case hight concentration it is possible that the CO2 values DIC and CH4 are high. I agree que le high CO2 and methane concentration Was reasonable in wetland ( and peat).

Not exactly sure, but if you are not rinsing well enough between samples, or particles of lime are picked up or disturbed on the contacts and eventually dissolve showing higher resistsnce (lower conductity).  10 readings seem excessive for stability, but unsure how you added lime and how you are sampling, adding water to soil or sampling water table or adding soil tomambeaker and mixing it up.  I dont know about any realignment of ions, the resistivity measures resistance to electrical current, higher resistance, purer water with fewer ions and cations to carry current.  If in sampling you are kicking in a bit of lime dust, and lowering probe, the lime dust will be temporarily concentrated in the probe and diluting to equilibrum, increasing restance.  This might be a possible explanation, but if the meter is jumping wildly about, I would check for a loose wire connection or faulty contact in probe or probe to instrument.  If you can borrow one or take a sample over to another lab, see if you have same result.

SI is dependent on the temperature and pH of the sample. do they have the same pH and temperature. If these parameters are higher in the sample #2, this would be the reason you got a higher number for SI. Since both SI numbers are positive, it denotes that both samples are over-saturated with the ferrihydrite and will cause precipitation.

I hope this answer helps. When are you going back to Sri Lanka. I might be back probably next year.

Dear Ebrahim:

Look at the formula for the thickness of the diffuse electric double layer in the Gouy-Chapman theory. The charge of the ion is in the denominator . Therefore the thickness of the diffusion layer decreases with increasing ionic charge.

Regards.

I work on a Mac, and have found a convenient way to run Phreeqc has been through the R environment using the R package that supports connection to Phreeqc.  I use R for much of my geochemical interpretation and graphics display so adding a connection to Phreeqc made sense to me since it gave me access to graphical display in a system I was familiar with.

Most of what I have worked on recently is evaporation modelling but the basics are the same.

The following R code starts up and runs a model:

library(phreeqc)

library(ggplot2)

phrLoadDatabaseString(pitzer.dat)

phrSetOutputStringsOn(TRUE)

phrRunFile("evaporate bulk sample 15C.txt")

model2 <- phrGetOutputStrings()

selectedOutputGFL15 <- data.frame(phrGetSelectedOutput())

writeLines(model2, "bulk run 15C prop steps.txt")

path3.K2.Mg.SO4.GFL <- as.data.frame(cbind(selectedOutputGFL15$n1.K.mol.kgw.,

selectedOutputGFL15$n1.Mg.mol.kgw.,

selectedOutputGFL15$n1.S.mol.kgw. ))

names(path3.K2.Mg.SO4.GFL) <- c("Kraw", "Mgraw", "Sraw")

... and now we can start making composition plots of the K2, Mg and SO4 data I pulled out of the run.

1) the file you run in phreeqc is just a text file (see below).

2) make sure to turn on OutputStrings, you will need them.

3) You get two outputs a) model2 in the code ends up with the normal run output, easy to read, but not east to do anything else with, and b) selectedOutputGFL15 is variables selected in the run file that are available in a matrix-like form.  I take out the parts I need for building graphics.

I'm using ggplot2 for graphics in R.  Very flexible and publication quality.  Lots of examples available.

The run file look like:

TITLE Brine Project (pitzer)

SOLUTION 1 Bulk Sample Initial Composition

units mg/L

pH 7.0

temp 15.0

density 1.21

Ca 427

Na 109312

... other elements 

S(6) 13542 as SO4

C(4) 300 as HCO3

EQUILIBRIUM_PHASES 1

Anhydrite 0.0 0.0

Bischofite 0.0 0.0

Bloedite 0.0 0.0

Borax 0.0 0.0

..pick which phases you want to dissolve/precipitate

Thenardite 0.0 0.0

Trona 0.0 0.0

INCREMENTAL_REACTIONS true 

REACTION 1

H2O -1

7.72 6.64 5.72 4.92 4.24 3.65 3.14 2.71 2.33 2.01 1.73 1.49 1.28 1.10

0.95 0.82 0.70 0.61 0.52 0.45 moles

SELECTED_OUTPUT

-alkalinity

-water

-reaction

-totals Ca Mg ... and any other elements you want to track

-equilibrium_phases

Anhydrite Bischofite Borax Boric_acid,s Bloedite

Calcite Carnallite CO2(g) Dolomite

Epsomite Glaserite Glauberite Gypsum Halite Hexahydrite

Kainite Kieserite Leonite Magnesite Mirabilite Polyhalite

Schoenite Sylvite Thenardite

END

You may want to use incremental steps as well, but perhaps not, I'm not sure exactly what you need.  I am doing evaporation, so my reaction is to remove water.  You will want to modify pH in steps either as a reaction or as multiple solutions.

This is a very rough start I know, but I hope it helps you see ways to get started.  Using phreeqc from R is not the only option, but it has worked very well for me on a Mac (the interactive and graphical interfaces are only available for people stuck on Windows ;-)

EPMA

 oky thanks Kenneth M Towe 

 THANK YOU DEAR FREIND SO YOU MEAN HYDROCHEMICAL SIMULATION BY SATURATION INDEX CALCULATION M

Dear Hassan,