particle_size_and_contamination
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| particle_size_and_contamination [2024/11/04 01:24] – nefcadmin | particle_size_and_contamination [2025/04/28 10:09] (current) – [19th October 2023 - MLA/2015/00088 - Mid-licence sampling] nefcadmin | ||
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| Much of the contamination within sediment is due to the adsorption of waterborne contamination onto the surface of the particles within the sediment. | Much of the contamination within sediment is due to the adsorption of waterborne contamination onto the surface of the particles within the sediment. | ||
| - | Smaller particles have a higher area per unit weight of material: | + | Smaller particles have a higher area per unit weight of material, so for 1litre of material (10cm x 10cm x 10cm cube with a surface area of 0.06m< |
| * 1 cm diameter spheres: Total surface area ≈ 0.6m< | * 1 cm diameter spheres: Total surface area ≈ 0.6m< | ||
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| The level of contamination is controlled by many factors, local contamination release, flow of the river etc.. So the role of surface area can be difficult to determine in the chemical analyses of different sediments. | The level of contamination is controlled by many factors, local contamination release, flow of the river etc.. So the role of surface area can be difficult to determine in the chemical analyses of different sediments. | ||
| - | The overspill from dredging barges and the resuspension which happens during dredging is mainly composed of the finest particles within the sediment. | + | The overspill from dredging barges and the resuspension which happens during dredging is mainly composed of the finest particles within the sediment. |
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| + | It should also be born in mind that PCBs and other long lived organic contaminants bioaccumulate in seals through their food sources and then passes to the pup during lactation. | ||
| ===== 19th October 2023 - MLA/ | ===== 19th October 2023 - MLA/ | ||
| - | The set of samples taken as part of the mid-licence sampling of the River Tees dredge disposal licence show a strong correlation between relative total surface area and the level of polycyclic aromatic hydrocarbon contamination. | + | The set of samples taken as part of the mid-licence sampling of the River Tees dredge disposal licence show a strong correlation between relative total surface area and the level of polycyclic aromatic hydrocarbon contamination. |
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| Particles less than 1um in size account for between 75 and 95% of the surface area of the sediment. | Particles less than 1um in size account for between 75 and 95% of the surface area of the sediment. | ||
| - | ==== Gorham-Test PAH Toxicity Measure | + | ==== Polycyclic Aromatic Hydrocarbons ===== |
| + | All the analysis carried out has ignored the sediment sample taken at the Chart 7 position, near to South Bank Quay, as this area had been extensively dredged to clean up after the spills and contamination of the River Bed which occurred during the construction of the new quay. This sample showed the highest total surface area being composed of almost entirely clay / silt and a relatively low level of contamination. | ||
| + | [[Teesworks - Recorded Contamination of Tees by Closed Bucket Dredging]] | ||
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| + | ==== Gorham-Test PAH Toxicity Measure ==== | ||
| {{this> | {{this> | ||
| + | Aside from the sediment sample taken in Chart 7 area, there is a strong relationship between surface area and long term toxicity of the sediment due to high molecular weight PAHs. | ||
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| + | ==== Role of Surface Area and Total Hydrocarbon Content on Individual PAHs ==== | ||
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| + | Graphical for many of the PAHs there is a visibly strong relationship between surface area and the measured level of PAH. Many PAHs are hydrophobic and are known to adsorb to mineral surfaces, it is also likely that many will be soluble in other hydrocarbon contamination present. | ||
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| + | This composite plot shows each PAH plotted against surface area, the chart title is the chemical name, followed by the R-squared values for the linear fit to total surface area and total hydrocarbon conent. | ||
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| + | {{this> | ||
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| + | ==== Role of Surface Area and Total Hydrocarbon Content on Individual PCBs ==== | ||
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| + | The same plots and fitting are reproduced for PCBs below: | ||
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| + | {{this> | ||
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| + | ==== Role of Surface Area and Total Hydrocarbon Content on Individual Organochlorines ==== | ||
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| + | The same plots and fitting are reproduced for organochlorines below: | ||
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| + | {{this> | ||
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| + | ==== All PAHs ==== | ||
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| + | {{this> | ||
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| + | ==== HMW PAHs ==== | ||
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| + | {{this> | ||
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| + | {{this> | ||
| + | {{this> | ||
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| + | ==== LMW PAHs ==== | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | === Other PAHs ==== | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
| + | {{this> | ||
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particle_size_and_contamination.1730683462.txt.gz · Last modified: by nefcadmin