WITH THE DATA FILE SUBMITTED PLEASE USE ONLY SHEET FIVE (5) as it is the only corrected data. PLEASE DO NOT USE SHEET 1-4 ONLY SHEET 5 YOU HAVE TO USE.







North Wales Dee Estuary field and laboratory activity. Field sites visited were 



A. Prestatyn (eastern end)

B. Talacre (Point of Ayr)

C. Holywell (next to the recycling centre)

D. Flint (next to the castle)



In a group of 5 five individuals, each group sampled the following from each site visited;



1. Surface sediment sample ( it is worth qualitatively noting the grain size and organic content of sediment, since these parameters can influence the metal content of sediments, via surface area of absorption and chemical bonding.



2. Seaweeds (Fucus vesiculosus (common name bladder wrack) and Cladophora spp.



3. Other salt marsh vegetation (only for Holywell and Flint where salt marshes are located; e.g. Halimione portulacoides ( common name sea purslane).



4.l Sediment cores (only for Holywell and Flint where the sediments are cohesive enough to support coring). Note: sediments cores were sub-sampled (i.e. subdivided) into 2cm depth segments.



All samples were labelled as; group number followed by relevant letter that is assigned to each field site as listed above. the following abbreviations were used as suffixes to identify the sample type:



SS= Surface sediment

SC=Sediment core (the depth intervals also were included, e.g SC2-4 for sample between 2 and 4 cm depth in the core)

FV= Fucus vesiculosus

Cs= Cladophora spp.

HP= Halimione portulacoides







METHOD

Laboratory Session #1



. Samples collected from Dee estuary and subsequently dried in an oven

. Pestle and mortar

. plastic spatula

. 50 ml centrifuge tubes and tube racks

. Access to an analytical balance

. Small beaker, in which to stand 50 ml centrifuge tubes on an analytical balance

. Concentrated HNO3 (Nitric acid) obtained from a bottle with a dispensing pipette.

. deionised water

. Ultrasonic bath

. white paper towel



1. Label one 50 ml centrifuge tube for each sediment and vegetation sample collected during the Dee estuary fieldtrip. Note: use the sample labelling notation described in the fieldwork section of the Dee estuary activity booklet.

2. Carefully grind and homogenise each of the dried sediment and vegetation samples in turn using a pestle and a mortar. Note: between samples you should ensure that the pestle and mortar is washed thoroughly with deionised water and dry them with the white papers.

3. Using a plastic spatula and analytical balance carefully weigh about 0.5 grams of ground and homogenised sediment or vegetation sample into a separate 50 ml centrifuge tubes.

4. Take the 50 ml centrifuge tubes containing the weighed samples to one of the two fume cupboards and use the bottle dispensing pipette to slowly and carefully add 5 ml of concentrated nitric acid (HNO3) to each of the samples

5. Each group should also prepare one procedural blank by adding 5 ml of concentrated HNO3 to an empty 50 ml centrifuge tube. This tube will be labelled as follows: 1Blank if group one etc.

6. Place the rack closed to 50 ml tubes containing the samples and concentrated HNO3 (including procedural blank) into the ultrasonic bath for 10 minutes. This procedure is done so that the samples are agitated within the HNO3 such that all of the particles are in contact with the concentrated HNO3. Wipe the outside of the sample tubes dry when they are removed from the ultrasonic bath.

7. Place the 50 ml centrifuge tubes, containing samples and 5 ml of concentrated HNO3, in the identified location and leave for 7 days for a cold nitric acid extraction of metals. Note: the procedure adopted will not dissolve chemically resistant silicate grains and will only take the extractable metals into solution in the concentrated HNO3.









Laboratory session #2

Each group should have the following:



. 50 ml centrifuge tubes containing ground and homogenised Dee estuary samples and 5 ml of concentrated nitric acid (HNO3)

. ICP-OES autosampler tubes

. Buchner filtration apparatus, including filter papers

. Deionised water and dispensing bottles

.Funnels

. 50 ml volumetric flasks

1. Label the ICP-OES autosampler tubes with labels that match the Dee estuary samples as described in the Dee estuary activity booklet

2. Take the 50 ml centrifuge tubes containing samples and 5 ml of concentrated HNO3 to a fume cupboard and add deionised water approximately to the 20 ml mark on the tubes

3. Take the sample tubes, now containing 25 ml diluted HNO3, back to the group’s laborately bench area and use the Buchner filtration apparatus to filter each sample ( including the procedural blank. In turn.

4. Once the has been filtered through the Buchner filtration apparatus pour the filtrate, using a funnel into a 50 ml volumetric flask and make up to the mark with deionised water. Hold the cap on tightly and mix the contents of the volumetric flask thoroughly.

5. Fill the labelled ICP-OES sample tubes with the diluted HNO3 extract solutions, place in a rack and submit for metal determination by ICP-OES.

6. Record all sample data on to the master Excel file.





Your report should have the following:



1. Report layout and presentation (10%)

2. Introduction (10%)

3. Summary of field and laboratory methods (10%)

4. Data synthesis, analysis, interpretation and discussion including evidence of integration with published and scientific journal articles (20%)

5. Use of supporting figures and tables (20%)

6. Consideration of other marine pollutants that could be included in a more comprehensive follow-up environmental risk assessment study (20%). What else could we have done to improve the research or the study?

7. Conclusion (10%).



The report should include statistical analysis of the metal concentration data generated by the whole class. For example, for the metal concentration data it should be possible to consider and statistically test the following questions (and any other that can be identified):



1. Are there statistically significant differences between sampling sites?

2. Are there statistically significant differences between sample types?

3. Do certain metals behave in similar (or different) ways to other metals?

4. Do certain metals and sampling sites cluster together in their behaviour?

5. Are there statistically significant differences within (i.e. between different depth/time intervals) sediment cores?

6. Are there statistically significant differences between sediment cores?