During this practical we used Ion Chromatography (IC) and Inductively Coupled Plasma Spectrometry (ICPS) analysis to measure the concentrations of several potentially toxic metallic elements including Arsenic, Cadmium and Lead in water, sediments and plant tissue samples from ponds and reservoirs in Harpurhey, Northern Manchester.



Samples were compared from several locations and considered the accumulation of metals by different species of semi-aquatic macrophytes. The effect of on-going remediation at the sites and possibility of human exposure to potentially toxic metals were considered.



MATERIALS

1. Gloves and safety glasses

2. White plastic trays

3. 4 x aluminium foil beakers

4. Buchner apparatus

5. 4x30ml universal tubes

6. Deionised water bottles

7. 3 different plant samples

8. Marker pen

9. Scalpel and scissors

10. 25ml volumetric flask

11. Whatman grade 3 (6um) filter paper

12. 4 x 50ml flasks

13. Two point weighing balance

14. Sediment sample and water samples



METHODS

. Collect and dry samples



1. Collect and dry sediment= Cut a small section from a sediment core and put it into a labelled foil beaker and place it in the oven at 80 degree Celsius to dry for about 1 hour.



2. Wash and identify plants= At a sink, wash any superficial sediment off your plants and dab dry with paper towel.



3. Collect and dry plant tissue= Cut samples of leaves from two different species (each about 5g at this stage). Clean the samples with deionised water. Shred the tissue and place in separate, labelled foil beakers. Put in the oven at 80 degrees Celsius to dry.



. SUBSAMPLING AND ACID-DIGESTION

Acid Digestion MUST be performed in a fume cupboard/hood to protect you from fumes. You must wear plastic gloves and safety glasses at all times.



1. Collect subsample of dried sediment for Hot Acid Digest= Remove your dried sediment from the oven. Weigh a 2g subsample into a labelled 50ml flask. In the fume cupboard, add 5ml of 65% Nitric acid (HNO3). Place a marble on the top of the flask. Set on a hot-plate at about 85 degrees Celsius to digest. Allow the samples to evaporate almost to dryness. NB: It si important that none of the samples carbonise- it is therefore vital that one of your group watches the samples at all times.

When the acid has evaporated (or after 1 hour whichever is sooner), remove the flask form the hotplate and allow to cool; you may need to add a small amount (say up to 10ml) of deionised water to re-suspend the residue.



2. Collect subsamples of plant tissue for Cold Acid Digest= Remove the dried plant tissue from the oven. Weigh a 1g subsample of each type into labelled 50ml flasks. In the fume cupboard, add 5ml of 65% Nitric acid and set on a tray to digest for about 45 minutes. This tissue should digest quite easily without heating. However, keep an eye on your samples- if they prove recalcitrant, you may need to warm them slightly on the hotplate to speed the digestion process.



. Filtration

3. Filter the re-suspended, digested samples= Use a Buchner funnel for filtration under reduced air pressure. Use a 4.5um disposable filter paper. Decant the filtrate into a 25ml volumetric flask and make up to volume with deionised water. Decant into a labelled 25-30ml universal tube and set for ICPS. Results were collated and analysed using MS-Excel and SPSS.





The report should have



1. Report layout and presentation (10%)

2. Brief introduction (10%)

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

4. Data synthesis, analysis, interpretation and discussion, including evidence of integration with published reports and scientific journal articles (40%)

5. Use supporting figures and tables (20%)

6. Brief conclusion (10%)