I would say that sediment cores from the bottoms of relict channels or ponded areas/lakes along the river would give you both heavy metal content and dates.

many thanks Dr,  Green

Dear Sisira, we developed a methodology for the geogenic background of heavy metal data in catchments (dissolved and suspended phase), to be used as justification of exemptions according to EC Water framework Directive. The first version of the methodology was developed for the National Environmental Agency of Germany, the upgrade of the methodology was done on the Federal States level. The methodology is based on a statistical method of a pre-selected data base. The details will be published soon. In Germany it was applied to the Harz Mountains, to Saxony-Anhalt, Thuringia and Northrine Westfalia. For all catchments is considered the pre-industrial situation. In case you are interested in further details please contact me via e-mail: [email protected]. Best regards, Petra

 Dear Prof Dr, Schneider, 

I highly appreciate your reply. I will write your yahoo mail soon. Regards Sisira

Dear Sisira, I worked in a bay in Brazil with 210Pb to calculate sediment accumulation, In Sepetiba bay some industrial activities started on mid 1970s, I used small drop cores in shallow water and analyzed the data along the core, We found elements in the stratigraphic profile and could find the stratigraphy horizon, knowing that in 1975 the industry start dumping the waste in the bay, such as Zn. Attached is the article to give you a better idea of the work. Best regards, Heloisa

 Dear Prof. Borges 

many thanks 

Hi Sisira, long-term global signatures of heavy metal levels are captured in ice deposition layers and have been analysed from deep ice cores, with comparisons of pre-industrial to industrial times. Suggest you investigate the literature on pollutant records in ice cores from Greenland and Antarctica. For example, see Boutron et al 2011 Heavy Metals in Antarctic and Greenland Snow and Ice Cores: Man Induced Changes During the Last Millennia and Natural Variations During the Last Climatic Cycles, in Persistent Pollution – Past, Present and Future. http://link.springer.com/chapter/10.1007/978-3-642-17419-3_3

Dear Colin

many thanks for your answer.

Sisira,

Are you wanting to identify the amounts of heavy metals being leached into the river from natural geologic deposits prior to human industrialization? Identify the increase in heavy metal concentrations by subtracting pre-industrialization amounts from the industrial era concentrations?

Trying to clarify question for participants.

Aquatic plants are excellent monitors of heavy metals in rivers.  See papers by B.A. Whitton and coauthors (several papers in the 1980s) for methods. A simple solution we have used is to see if there are historical herbarium specimens in local collections (university or museum) in your area.  Assuming botanists were active in late 1800s or early 1900s, they will reflect concentrations of water chemistry in those years. They can be compared with plants collected in more recent years.

Please refer to the paper attached below and the shale value in that.

https://www.researchgate.net/publication/303699950_Assessing_the_ecological_health_risk_in_a_conserved_mangrove_ecosystem_due_to_heavy_metal_pollution_A_case_study_from_Sundarbans_Biosphere_Reserve_India

https://www.researchgate.net/publication/301644037_Identification_of_metal_tolerant_plant_species_in_mangrove_ecosystem_by_using_community_study_and_multivariate_analysis_a_case_study_from_Indian_Sunderban

Article Assessing the ecological health risk in a conserved mangrove...

Article Identification of metal tolerant plant species in mangrove e...

This two papers might help you, in some ways;

Cheers.

To answer your question thoroughly requires some additional information. In case of airborne contamination (e.g. lead and platinum group elements in surficial sediments near highways) or agricultural activities (e.g. fertilizers or soil amendment) a comparison between surficial and deep sediments will yield pre-industrial data(pay attention to comparability of grain size).

in case if stream sediments the situation becomes more complex. Originating from huge catchment areas, generally far upstream, a comparison of deep (local) sediment and overlying stream sediment certainly yields differences in element composition. Also in a sediment series with decreasing element concentrations the lowermost part still could be contaminated and will not provide true pre-industrial data. This occurs in early cultured areas, due to e.g. Roman or medieval mining activities. In contrary, finding higher concentrations in surficial materials is not necessarily due to (anthropogenic) contamination.  Whether or not the surficial sediment is contaminated and to what extend requires discriminating the anthropogenic from the geogenic (pre-industrial) element load at the very same material. Keeping in mind that only the elements in most stable bonding forms (silicates, stable oxides) will survive the processes of rock disintegration, relocation and transport provides a clue to a discrimination approach. Element loads due to industrial processes and agricultural activities occur in less stable bonding forms which are not able to survive the rigid conditions of rock disintegration and fluviatile transport. Therefore, in contrast to geogenic loads, they can be stripped off with rather soft chemical digestion methods, e.g. by methods of sequential elution, leaving the geogenic conc. When we applied these methods at depth profiles of contaminated stream sediments (e.g. River Elbe area, Germany) or following several 100 km from the spill site along the river banks (Tisza; Romania, Hungary) shows constant residual concentrations in the range of ubiquitous sediment background (pre-industrial) values, whereas the contaminants show the well known decrease from top to down (Elbe) or from the spill site downstream (Tisza).

So, in the case of stream sediments I would recommend to use methods of sequential eution like the rather simple BCR method (Ure AM, Quevauviller Ph, Muntau H, Gripink B. Speciation of heavy metals in soils and sediments. An account of the improvement and harmonization of extraction techniques undertaken under auspices of the BCR of the Commission of the European Communities. Inter J Environ Anal Chem. 1993;51:135-151. )

In our studies we used a more elaborated method. You will find it via my Research Gate page (publication on contamination of Elbe sediments  (2013) and Tisza sediments (2006))

Kind regards

D. Zachmann

Hallo Prof. Dr Zachmann

Many thanks for your clarification. 

Can I use world average shale as background values while calculating the geoaccumulation index of trace metals ?

Sisira - I added a comment to your original question on this issue with reference to the GAI.