Wheal Maid Field Trip

Our aim

It was important to us that the design of both our parts, our filter and the intended implementation for the project was a reflection of a real-world problem. This insight was largely given to us by the RRI framework, as it stressed the significance of society's role in science and it underlined the problem with innovating in an isolated manner. Motivated by our desire to base our science on our own data taken outside of the lab, we went on a field trip.

Wheal Maid forms part of the Consolidation Mine, part of the Cornwall and West Devon Mining Landscape World Heritage Site. Wheal Maid was mined until the 1870s, and then became site for taking fine-grained mineral processing waste (tailings) from the mill facilities at the former Mount Wellington tin mine during the 1970s and 80s. The waste was taken to a valley infill at Wheal Maid consisting of two lagoons separated by three dams and contains approximately 220,000m³ of tailings. An investigation by the Environmental Agency to conduct an inspection into environmental quality, which took place in 2007, concluded that Wheal Maid is a contaminated site. It was also showed that the site is causing pollution of the St. Day Stream by leaching of arsenic, cadmium, copper, chromium, iron, lead, nickel and zinc through the toe of the lower lagoon. (Carrick District Council, 2008). For this reason we decided to conduct our primary field work at this site, collecting water samples from these lagoons.

Figure 1: One of the lagoons at Wheal Maid.

Methods

In order conduct our data collection safely, we completed the appropriate risk assessment forms. We also used protocol, designed to enable efficient collection and filtration of the samples at the site before they were to be transported back and placed in a cold store for analysis. We also had a standard operating procedures for sample analysis using the ICP-OES machine. We were given permission to use Greenpeace's ICP-OES machine following our stakeholder meeting with them. Details of the protocols and risk assessments can be found on our safety page.

On 14th July 2017 we arrived at Wheal Maid with a PhD student from the Cambourne School of Mines at the University of Exeter, miss Tomasa Sbaffi. She met us in order to help us with taking water samples due to her experience with the process and knowledge of the site. We sampled one of the lagoons and the pond shown in figure 2.

The water bodies were sampled by taking 1L of water from each of the 4 sites at the lagoon (A-D) and the pond (E-H) as labelled in figure 2.

Figure 2: Satellite map of Wheal Maid site with the lagoon marked A-D and the pond marked E-H.

Figure 3 was created using Vidana software to determine the percentage decrease in size of the lagoon and the pond since the Google Maps satellite photo was taken in January 2017. This reduction in surface area could be due to a number of factors, such as seasonality, which is likely to have caused an increase in the concentration of metal ions.

Figure 3: The percentage cover of the lagoon (left) and pond (right), sampled on 14th July 2017, has reduced by 78% and 77% respectively since January 2017. This area was determined from the location of the sampling sites around the edge of the lake and visually from Figure 2. (Geoplaner.com , 2017) (Hedkey, 2017)

We then filtered 150ml of each sample into three falcon tubes using yellow 100µm filter and then preceded to filter them further through a smaller 0.2µm filter. We treated the blanks containing Mili Q water as controls and processed them the same way as the samples. The pH of all of the samples was tested using litmus paper which all came out as ~pH 3. The samples were sealed in bags and transported back to Exeter to be placed in a cold room to await further analysis.

Figure 4: Laura and Jake B preparing and analysing the samples at Wheal Maid

Results

pH of the Water Bodies

Analyising the samples, we found the pH, and this has been displayed in table 1. An ANOVA (analysis of variance) was performed on the pH of the samples after storage from the different water bodies to see if there was a statistical difference between the two, shown in table 2.

Table 1: pH of the lagoon and pond sites at Wheal Maid.
Site	Lagoon	Pond
	pH
N	24	11
Mean	2.80	2.77
Standard deviation	0.155	0.180
Standard error	0.0317	0.0514

Table 2: ANOVA statistic output testing the variation in pH of the lagoon and pond sites at Wheal Maid.
Comparison	ANOVA p-value	Significant
Lagoon pH vs pond pH	0.640	No

Metal ion composition ICP-OES results

Dissolved Metals	Standards (mg/L)	Lagoon (mg/L)	Pond (mg/L)
Aluminium (Al)	0.200	6.726	50.584
Boron (B)	0.300	0.090	0.246
Cadmium (Cd)	0.003	0.007	0.027
Copper (Cu)	2.000	1.065	4.334
Iron (Fe)	0.200	3.445	16.307
Nickle (Ni)	0.020	0.023	0.197
Thallium (Ti)	0.0005	0.0280	0.0004
Zinc (Zn)	3.000	2.897	25.738

Table 3: Dissolved metal ion composition of samples taken from the Lagoon and Pond sites at Wheal Maid. Stars indicate which elements are found to have higher concentrations than the drinking water standards. (Defra, 2017) (Lenntech.com , 2017) (US EPA, 2015)

Discussion and Conclusion

Analysis of the results from the field trip to Wheal Jane helped inform our work in the laboratory. Specifically it allowed us to identified which the metal binding proteins we wanted to use in our constructs in order to bind to metal ions that were significantly above their standards. The proteins we to investigate were Mouse Metallothionein (binding to Cd, Cu and Zn), Synechococcus Metallothionein (binding to Cd and Zn), Synechococcus Plastocyanin (binding to Cu) and a histidine (to bind Ni).

References

Carrick District Council, Record of Determination of Wheal Maid Tailings Lagoons (2008) Available at: https://www.cornwall.gov.uk/media/3625647/2008-09-16-Record-of-Determination.pdf [Accessed 7 August 2017]

Screen shots of % cover credit: Hedkey, J. (2017). Vidana. Marine spatial ecology lab.

Screenshots of maps credit: Geoplaner.com. (2017). GPS Geoplaner online. [online] Available at: http://www.geoplaner.com/ [Accessed 07 Aug. 2017]

Defra (2017). Drinking water inspectorate. [ebook] London, pp.1-5. Available at: http://Dwi.defra.gov.uk/consumers/advice-leaflet/standards.pdf.

Lenntech.com. (2017). WHO's drinking water standards. [online] Available at: http://www.lenntech.com/applications/drinking/standards/who-s-drinking-water-standards.htm [Accessed 12 Sep. 2017].

US EPA. (2015). National Primary Drinking Water Regulations | US EPA. [online] Available at: HTTPS://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations [Accessed 12 Sep. 2017].

Team:Exeter/HP/Fieldtrips