Heavy Metal Pollution - Science topic

Biogenic synthesis techniques can enhance heavy metal extraction in plants by creating nanoparticles that improve uptake and tolerance, along with genetic engineering to overexpress relevant genes. Additionally, combining these nanoparticles with growth promoters and using sensors can optimize phytoremediation efficiency in contaminated soils.

Depends on a reagent that you use for adjusting pH.

Phreeqc modeling shows that pH of 1 m Pb(NO3)2 solution is close to 5.4.

Adjusting pH to higher values requires addition of base and can cause precipitation of Pb(OH)2.

Hello Noor,

I downloaded the previous paper through the library. It's nice work but I did wonder how much Ag and Cu might be released into the environment at the industrial scale.

Industrially, my guess is that you would have two filters operating at any one time in series. In operation, the second would be promoted to first then replaced with a new unit. You'd need some type of indicator to prompt this change.

That's the best I can do, Paul.

Artificial intelligence (AI) and machine learning techniques can be effectively utilized to predict, monitor, and mitigate antimony contamination through a combination of data analysis, modelling, and decision support systems.

This means that you want to have complete imaginable knowledge about the quality of measurement and analysis results and no doubts as to the correctness of the method of determining the total uncertainty of these results. Methodologically, this is a very correct approach and very forward-looking. Many books and even more articles have been written on each of these four problem groups that you distinguished. What has already been established and proposed on these topics certainly needs to be somehow organized and introduced into existing research methodologies, e.g. by creating recommendations and requirements. Research and government institutions do it. However, the crux of the matter is whether these recommendations and requirements are applied in research work, including in the work of analytical laboratories. Current requirements, e.g. regarding the obligation to provide uncertainty estimates of measurement and analytical results, are treated rather formally. This could change if the recipients of analytical information were dependent on the uncertainty values of specific results, and not only on average values, in their scientific conclusions and assessments of the state of the environment. But this is my point of view as an analytical chemist (retired). And as we know, the point of view depends on the point of sitting. Regards.

ZJ

Perhaps ok for undergraduate thesis.

Dear Kennedy O. Ouma please do recommend my answer if helpful

Guideline values for metals in stream sediments of sub-Saharan Africa can vary depending on the specific regulations and standards set by individual countries or international organizations. There isn't a single universal set of guideline values that applies to the entire sub-Saharan African region. Instead, different countries may have their own environmental quality standards and guidelines for metals in sediments based on factors such as local geological conditions, environmental priorities, and potential risks.

For guidance on acceptable levels of metals in stream sediments, researchers, environmental agencies, and mining companies in sub-Saharan Africa typically refer to:

Given the variability in guidelines and regulations across sub-Saharan African countries, it's essential to consult with local environmental authorities, research institutions, and relevant stakeholders when conducting sediment quality assessments or environmental impact assessments. Additionally, international organizations like the United Nations Environment Programme (UNEP) and the African Union (AU) may provide guidance on environmental standards and regulations that can be applicable to the region.

According to a review and meta-analysis of potential impacts of ocean acidification on marine calcifiers from the Southern Ocean, heavy metal pollution is not a direct cause of defects in CaCO3 crystals from marine calcifiers 1. However, heavy metals can indirectly affect the formation of CaCO3 crystals by altering the pH levels of seawater. Heavy metals can also cause oxidative stress and damage to the cells of marine calcifiers, which can lead to defects in CaCO3 crystals 2.

1: Figuerola, B., Hancock, A. M., Bax, N., Cummings, V. J., Downey, R., Griffiths, H. J., Smith, J., & Stark, J. S. (2021). A Review and Meta-Analysis of Potential Impacts of Ocean Acidification on Marine Calcifiers From the Southern Ocean. Frontiers in Marine Science, 8. https://doi.org/10.3389/fmars.2021.584445

2: Heavy Metal Pollution: Source, Impact, and Remedies. (2011). In Heavy Metals in Water: Presence, Removal and Safety (pp. 1-28). Springer Netherlands. https://doi.org/10.1007/978-94-007-1914-9_1

Learn more:

Heavy metals enter the environment through various natural and anthropogenic (human-caused) processes. While some heavy metals occur naturally in the Earth's crust, human activities significantly contribute to the release and accumulation of these metals in the environment. The primary sources of heavy metal pollution include:

Once heavy metals enter the environment, they can persist for long periods and bioaccumulate in the food chain, becoming more concentrated as they move up the trophic levels.

The presence of heavy metals in the environment can have detrimental effects on ecosystems and human health. They can lead to toxic effects in plants, animals, and humans, causing various health issues such as neurological disorders, kidney damage, and cancers. To mitigate heavy metal pollution, proper waste management, wastewater treatment, and pollution control measures are essential. Additionally, adopting cleaner technologies and sustainable practices can help reduce the release of heavy metals into the environment.

On SpringerLink I found the complete article with the two missing pages of the list of references. Interestingly enough, there was no Muller (1979) reference in the list. Makes me wonder if it even exists. The GeoJournal that everybody uses in their references didn't even exist in 1969.

From now on I will use the article that you shared. Thanks.

Noor Ul Ain , Generally atomic adsorption spectroscopy will be better. You have better selectivity and lower quantification limit.

The heavy metal pollution index is a measure of the levels of heavy metals present in a particular environment, such as soil, water, or air. It is typically calculated by measuring the concentration of a number of different heavy metals in the environment and combining these measurements into a single index value.

There are several different ways to calculate the heavy metal pollution index, and the specific method used can depend on the specific heavy metals being measured and the goals of the analysis. Some common methods for calculating the heavy metal pollution index include:

Summing the concentrations of individual heavy metals: In this approach, the heavy metal pollution index is calculated by summing the concentrations of each heavy metal being measured, with each metal being given a weight based on its toxicity or potential for harm to human health or the environment.

Using a standardized index: There are several standardized heavy metal pollution indices that have been developed, such as the Pollution Load Index (PLI) or the Geoaccumulation Index (Igeo). These indices use a formula that takes into account the concentrations of different heavy metals and the potential for these metals to accumulate in the environment or affect human health.

Using statistical methods: In some cases, statistical methods such as factor analysis or principal component analysis may be used to identify the most important heavy metals contributing to pollution in a particular environment and to calculate an overall heavy metal pollution index.

It is important to note that the heavy metal pollution index is just one tool that can be used to assess the levels of heavy metals in an environment and the potential risks associated with these metals. Other factors, such as the presence of other contaminants and the sensitivity of the local ecosystem, may also be taken into consideration when evaluating the potential impact of heavy metal pollutants.

The chitosan is a biopolymer that is considered an eco-friendly and efficient alternative of biological origin. Chitosan has become an actor in water treatment. Its use in coagulation/flocculation, adsorption and chitosan-assisted ultrafiltration processes.

By its properties of non-toxicity and biodegradability, chitosan can represent an effective substitute for mineral salts and synthetic polymers for the removal of turbidity in the treatment of drinking water but has the defect of increasing the TOC of the treated water.

Materials of biological origin such as chitosan appear to provide alternative and innovative solutions. This amino polysaccharide has great potential in water treatment due to its biological nature, its origin (obtained mainly from waste from the fishing industry), its non-toxicity, its polycationic character which distinguishes it from other polysaccharides and natural polymers, and its technological versatility. This biopolymer has indeed aroused growing interest since the 2000s to recover and eliminate contaminants present in industrial effluents due to its wide range of applications.

Regards

Graphene based adsorbents for remediation of noxious pollutants from wastewater is used.Adsorption is one of the most efficient techniques for removing all most all types of pollutants i.e. inorganics and organics.After using in the wastewater purification as adsorbents of different toxic species (e.g., heavy metal ions and organic compounds), the spent graphene-based materials should be separated from the medium, regenerated, and then recycled. The separation of these materials is a boring process due to their small size. It depends on the nature of materials. Different techniques have been employed to effectively separate graphene-based materials from wastewater, among which the most substantial are centrifugation, cross-flow filtration, field-flow fractionation, and electric field (Ali et al., 2018c; Kim et al., 2006; Moeser et al., 2004. The recyclability of spent graphene-based materials is the other emergent problem.

So too much important to understand advantages and disadvantages of the processes.

Tannery effluent have large amount of Cr. Iron also may be present in many type of wastewater due to treated systems and pipe. Cu I don't find it in most copper industries wastewat such as wire. Ni and Co in the military industries wastewater. In fact the presence of heavy metals depending on both industry effluent and regulation limits. I mean some regulations accepted high concentration of heavy metals in wastewater.

Indeed, This clay has a low retention capacity

Its interfoliar distance is of the order of 7 A, low compared to other kinds of clay

Kaolinite forms in well-drained soils, by acidic pH.

Il faut voir les rapports des nations unies

Tshivute Iipinge you may contact Dr Ibrahim A. Allamin in Nigeria for further advise as he did the experiment in our lab. Would be interesting to see the capability of this hardy plant to remediate the contaminated soil. In addition you can do metagenomic studies to see population shifts/succession.

The workers in secondary lead smelters lead normally suffer from the lead poison. It is body accumulated poison which causes by the time a sever effect on the lungs, kidneys, blood, bones, and brain. I worked for several years in lead smelters and suffer from this poison. The treatment of such poison is to follow the following points:

1. The importance of staying away from sources of pollution until starts to go down, or reduce the exposure time.

2. Make sure to wear personal protective clothing and focus on appropriate respiratory masks.

3. The lead in the lungs and blood need to be extracted by special medicines, The pomegranate drink is a good extracted liquid for the heavy metals like lead.

I would like you to focuses on the first point as soon as possible in order to get raped to reduce lead poison concentration.

Is frog a model organism for metal toxicity assay? How much heavy metal-containing meals do frogs consume? What does the literature say about effect of heavy metals on frogs? How many people consume frog meat? People in terms of cultures. These are some of the areas of your research that you must tidy up. My answer is Yes! you can. However, your ecotoxicological model will be localized.

Sure! i also need the same for Africa (Sub Sahara))

How many mechanisms are there between heavy metal pollutants and microorganisms? This question isnt directional as too many heavy metals or microorganisms are involved and of course mechanism differs

Thanks Anju Baroth

Hi Xinlin, Would you kindly put some parameters around the claim? Paul.

Brassica juncea is the most suitable plant for phytoremediation of heavy metals.

First of all, It depends on the type of adsorbent material that you used.

In heavy metal removal processes, desorption/regeneration of adsorbents is one of the essential aspects as it controls the economy of water treatment technology.

For effective regeneration of adsorbents and metal recovery, acids (such as HCl, H₂SO₄, HNO₃, HCOOH and CH₃COOH), alkalis (such as NaOH, NaHCO₃, Na₂

CO₃, KOH and K₂CO₃), salts (such as NaCl, KCl, (NH₄)₂SO₄, CaCl₂2H₂O, NH₄NO₃, KNO₃ and C₆H₅Na₃O₇2H₂O), deionized water, chelating agents and buffer solutions (such as bicarbonate, phosphate and tris) were used in various studies.

I think phytoremediation is the most feasible method for removal of heavy metals from contaminated soil.

Chemical Speciation and Potential Mobility of Heavy Metals ...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3330713/

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!

Guideline value; 0.02 mg/l (20 µg/l) Occurrence; Concentrations in groundwater less than 0.001 µg/l; concentrations in surface water less than 0.2 µg/l; concentrations in drinking-water appear to be less than 5 µg/l .

Tolerable daily intake (TDI) 6 µg/kg body weight, based on a NOAEL of 6.0 mg/kg body weight per day for decreased body weight gain and reduced food and water intake in a 90-day study in which rats were administered potassium antimony tartrate in drinking-water, using an uncertainty factor of 1000 (100 for interspecies and intraspecies variation, 10 for the short duration of the study).

No permissible limits for Copper (Cu) and Chromium (Cr) in waste water.

The available permissible limits in guidelines are for drinking water

Cu = 2 mg/L

Cr = 0.05 mg/L

Please see the following link

These biomass types serve as a basis for newly developed metal biosorption processes foreseen particularly as a competitive means for the detoxification of metal - bearing industrial effluents.........Plants absorb heavy metals along with essential elements from the soil and evolved different..... Atomic absorption spectrophotometry, and reflectance spectrometry can be used .For details consult https://www.science.gov

You can also use the ICP-OES, for this you must incinerate the sample at 450 degrees and dissolve it in 1.5% nitric acid

I think that if possible, but doing the analyzes separately

Hi Mirza,

Indices are efficiently utilized in pollution evaluation of water resources, and their application depends on the purpose and objectives to which they are intended for. Besides pollution monitoring of water resources, creation of indices may cover trend analysis and enforcement of standards.

If you want to develop an index to answer or solve your research problem, you need to follow the sequence below;

1- Identify and select the relevant parameters as a good candidates for the index.

2- Calculate the subindex of each parameter.

3- Assign weightage (Priority or importance) to the selected parameters.

4- Aggregate the subindex and weightage to get the overall index which can be used practically to classify the water for various uses.

Find the attached publication and links for more references;

Best regards.

Hello Asmat,

I have published a paper that reported extreme metal pollution load indices of up to 31. However this was NOT in marine sediments. It was in peri-urban freshwater dams that received a lot of urban run-off and effluent discharges. I suppose it is possible to have values of up to 100 after a prolonged period of pollution. This is because metals generally adsorb onto sediments, therefore keep accumulating over time. You also need to be sure that the metal levels you are detecting in sediments are not due to the geochemistry of the bottom surface (as opposed to pollution).

Here is a link to our publication.

All compiled environmental guidelines and standards are shown here in the below link:

Dry-ashing and wet oxidation are the two widely adopted methods for extraction of heavy metals. For details go through this important descussion. https://www.researchgate.net/post/Which_method_should_I_us_for_extracting_heavy_metals_from_plants

Interesting

Interesting

If you see the philosophy of treatment of waste, we are only changing the form of pollution.

It can not be completely treated. Wastewater is treated, sludge is produced, land pollution is created. Air pollutants are absorbed, water pollution is created. Solid waste are scientifically burnt air pollution is created and so on..

Similar is the case in Phyto- remediation the phyto- accumulation helps saying that heavy metals are reduced.

The treatment technology is basically pollution transformation process.

I am very sorry sir. Thanks for your co-operation. If possible please try to provide me. If not possible then its ok.

Dear Mr. Kan,

Thank you for your mesage.

The parameters I have set are seperate for environment and processing.

It is true that heavy metals will not disappear no matter what process is applied. However, could it be possible that heavy metals in water that is used for wet processing could accumulate on green coffee? If yes, how could that be possible and what are the possible risks.

My thesis is to research the presence of these contaminants on a risk based approach. I am currently working as a graduate intern at Jacobs Douwe Egberts in Utrecht and this thesis is to improve the Material Monitoring Program of JDE. Unfortunatley there are not many specific research reports about these topics. At least I have not been successful finding a lot.

I hope that you could help me further in my study.

Kind regards,

Munish Bidjai

m.bidjai@hotmail.com or munish.bidjai@JDEcofee.com 

Thank you your suggestions.

I have worked with few metal combinations................

Please follow EPA protocol for heavy metal analysis.

Not sure exactly what you need.  A spreadsheet such as Excel would give you different options for fitting you data (linear, exponential, polynomial, etc.) to a model as well as giving you an R^2 as a "goodness of fit"  that can be used to provide a statistical probability of a trend.  If you just need to determine the probability of whether a trend exists, you might consider a Mann-Kendall statistical test for trend.    

Explain Nisso softness? 

Hi Linee

Toxicity of Chromium III is very different from that of Chromium VI

That is the first thing you need to define

Dear Linus Aposu

You can following the attached paper too.

regards

Dear Davina

Please kindly  Follow : 

Food and Agriculture Organization (FAO) Heavy Metal Regulations – Faolex. Legal Notice no. 66/2003. 2003. http://faolex.fao.org/docs/pdf/eri42405.pdf.

FAO/WHO (FAO/World Health Organization) (2002) Codex alimentarius—general standards for contaminants and toxins in food. schedule 1 maximum and guideline levels for contaminants and toxins in food. Reference CX/FAC 02/16. Joint FAO/WHO Food Standards Programme, Codex Committee, Rotterdam, The Netherlands

A . Fish and Fisheries Products Hazards and Controls Guidance. 3. College Park: Center for Food Safety and Applied Nutrition, US Food and Drug Administration; 2001.

they have been listed by the US Environmental Agency (USEPA) based on their potential for human exposure and health risk (Birungi et al. 2007).

The joint FAO/WHO Expert  Committee recommended a PTWI concentration

under 5 lg/kg body weights for mercury(Torres-Escribano et al. 2010).

Best regards, parisa

Samantha - I understand the kind of diagram you are looking for. I dont recall seeing one and Leonardo is right, such a diagram would be deceptively and potentially dangerously simple (actually so is the pH/nutrient one). "Availability" or toxicity/risk is a function of many things not least redox potential, pH, organic matter content, source of contamination, age of contamination, sequioxide content, CEC etc etc. There has been some progress trying to develop "models" for estimating risk / toxicity from commonly measured soil parameters (such as pH, CEC, OM, Fe). Take a look at previous discussion on the topic - link below.

Kindly read the articles and follow the links

Regards,

Rabbul

old book of "Colorimetric determination of traces of metals" Sandell, E.B. NY 1944 you can find methodology for heavy metals

It depends on the forms of metals, solubility of the metal forms, the demands of the organism in terms of the metal (e.g. essential metals like Fe, Si for e.g. the exoskeletion of marine organisms) or their analoges, the life cycle of the organism etc. Usually, pollutants are concentrated in the organisc phase of the sediments.

Dear Patricia

Extracting and analysing metals from areial parts   and roots and purification of metals in order to get it back into industry could be done.

Best regards

Thank you all for answering my question!

Well, you have to read and search about Hg sources in the environment and then study your area and see if there is discharge source which may contain Hg. also you can make the same for other metals.

also you have to keep in mind that metals are present in marine environment but in a low or high concentrations varying according to the metal so you have to know the background concentrations of metals in environment. 

regards

 Dear Safia Habila

Thank you so much for feedback. I need the permissible limit of  soil not water.

Dear Shaimaa Sabeh

This lead and after that cadmium. But in camel milk: 

please follow : https://doaj.org/toc/1678-457X/36

2016;36(1):132-139 DOI 10.1590/1678-457X.0069.

Evaluation of mineral content and heavy metals of dromedary camel milk in Iran. Food Sci. Technol (Campinas) [online]. 2016, vol.36, n.4, pp.717-723.  Epub Oct 13, 2016. ISSN 0101-2061.  http://dx.doi.org/10.1590/1678-457x.16116.

The aim of this study was to determine the amount of major mineral compounds and heavy metals of camel milk in Iran. For this purpose camel milk samples were collected from seven regions of Iran include Qazvin, Golestan, Semnan, Sistan-Baluchestan, Khuzestan, Bushehr and Tehran. The samples were analyzed using Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) method. The results showed that among the mineral contents, iron and zinc of camel milk were greater than bovine milk. Based on the codex standard 193-2007 standards, the maximum acceptable limit for lead and cadmium is 20 µg/kg and 10 µg/kg, respectively. The results of this study showed that the measured amounts of lead, cadmium and nickel in all samples were less than the acceptable limit for bovine milk. Bovine milk and dairy products are a poor source of iron, while the obtained data revealed that camel milk is a major source of minerals, especially iron. The camel milk’s iron was 10 times more than bovine milk. However, variations in mineral content in camel milk could be due to feed, stage of lactation, milk collection time, drought conditions, environmental conditions and associated analytical methods. Camel milk recommended as a valuable source of food for the human.

Keywords : camel milk; mineral element; heavy metal; Inductively Coupled Plasma (ICP).

 my dear, i agree with Paul Milham ·

The case of bacterial multimetal resistance  is a bit different from resistance to single metal but is more worthy as a tool for bioremediation. I am particularly interested to tolerance and resistance strategy and the cellular, biochemical and molecular mechanism involved there. How does escape mechanism and tolerance in course of time evolves as an adaptive  strategy and means of detoxification and/or removal?

Hi Nursyasya,

In terms of the species I won't be much help, but if you look into the literature on phytomining, I'm sure someone will have an example of a tropical plant that is a good bioaccumulator of gold. 

With regard to the analysis you have plenty of options, particularly with the low detection limits of ICP-MS. Firstly the soil - this depends on whether a significant proportion of your gold is associated with silicates, if not then it's relatively simple. Make sure your sample is dry, then digest the soil sample in aqua regia (3 parts conc HCl, 1 part conc HNO3) with a solid to liquid ratio of no more than 0.1. Due to the hazard involved in this stage, do this in small batches, generally a few grams in 50 mL depending on the expected content in the sample. Then filter and dilute the sample for analysis. Where you have silicate-associated gold, you may need to grind the sample significantly finer to release it. This is because silica phases will not dissolve to a significant extent in aqua regia.

The plant samples are most likely best dealt with by burning the plant matter and treating the ash as with the soil above. The issue here is trying to make the procedure reproducible so that you're experiments can be compared to each other. Therefore, you'll need the same part of the plant, with similar moisture contents, etc. The moisture is best removed by freeze drying to minimise potential plant decomposition during conventional drying. 

I'll add a caveat here that I'm by no means a biologist and so am happy to be corrected about my suggestion for the plant treatment.

If you need more detail or advice just ask. Good luck!

Cheers,

Laurence

Thank you all for your responses with valuable attachments.

 Dear   Khouloud BOUKADIDA 

Please follow the 

standard EPA documents

and also the best references which dear Mikhail reffered.

Best Regards

Parisa Ziarati

Maximum permissible levels in food based on WHO recommendations for the listed elements are:

Cd - 0.003 mg/L.

Cr - 0.05 mg/L.

Mn - 0.2 - 0.4 mg/L.

Ni - 0.02 mg/L.

Cu - 1.0 mg/L

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

 Dear Raj Singh

Thank you !!

Saif ultimate lelan

4.o9% = 4.09 Gm  Fe  in  100 Gm  crust

I have no study in this project.

Ms Excel is suitaible and easier for calculating Igeo. Simply draft your formula in Excel, input the metal conncentation in the sediment and the reference/background concentration of the particular metal and the correction factor......

Good luck to you

Hi Dear Farhad 

Please follow the articles: 

@Henrik

You are correct, assuming each sample is exactly 1.00g, and the volume is 50 mL.  Your calculation assumes that all 15 weight measurements are exactly 1 gram.  The spreadsheet should have separate columns for the weight extracted and volume used of each sample. 

Dear Md. Abdus Satter,

Please see the attached file. I wish  could be useful to you

Please check the following link.

With all due respect Prof. Ewald Schnug, but using HR-ICP-MS for measuring the concentration of "some heavy metals" in water is like using sledgehammer for cracking the nut. This technique is good for advanced measurements like isotope dilution for high precision purposes (et. forensic) etc., but not for measuring concentration of metals in water. In this case "regular" ICP-MS is enough. 

But Mr Ali abd-elrahem asks about simple method. I would suggest FAAS for elements with high concentrations (Ca, K, P, Mg) and GFAAS for elements at trace concentrations. These techniques are relatively easy in comparison to ICP-MS and even not mentioning HR-ICP-MS that requires skilled and experienced staff to operate.

Try using the command "type="none" in the plot line, then you add what you need using the command "text".

e.g.: 

plot(rdaf,type="none",scaling=2, main="RDA")

> text(rdaf,display="bp",cex=1.2,col="blue")

> text(rdaf,display="wa",cex=0.9)

Copper salts are not recommended for soils.Samall qauantities may be allowed

Lead nitrate is toxic and absorben by plants. Mercury  salts are hihgly toxic and is prohibited.  Chromates are soluble and end in freactic waters and is toxic

Hello

might be able help you do a book.

with regards

There is information and a useful spreadsheet available via the attached link Avinash (Water Quality Index 1.2). It takes into account most of the parameters you list and it can probably be adapted to meet your specific requirements. There are numerous other indices available.

Dear Eleni

Please follow the page : 

As I have done this method many times.

Best Regards