Following reports by the Guyana Water Inc. (GWI) that tests on the Port Kaituma River had registered mercury contamination levels above WHO guidelines, a recent report from the Guyana Geology and Mines Commission (GGMC) has found that the presence of the metal in the river is not significant.
However, the report noted that high enough levels of mercury were found in the river sediment to indicate that aquatic species within the area may be affected. It was also noted, however, that further research would be required to provide evidence on this front and for an advisory to be issued regarding the consumption of aquatic species in the area.
Acknowledging the differences in readings, the report also recommended that not only are the results shared with GWI, but that the methodologies and results from the entities be compared. However, it should be noted that the GWI, after conducting follow up tests, had revealed that the mercury levels in the water of the River had abated. They had also said that further tests would be done to ensure that the results stay the same, as well as tests in other communities that are near to mining operations.
A joint team from the Environmental Protection Agency (EPA) and the GGMC was sent to Port Kaituma in July after the Environmental Division of the Commission received a letter from GWI stating that they had tested the water being supplied to the residents of Port Kaituma from the Kaituma River, and found that it was contaminated with mercury in concentrations higher than the guideline set out by the World Health Organisation (WHO).
The report related that as a result, GWI ceased pumping water from the Port Kaituma River and requested an intervention from relevant authorities. The investigation followed and a final report was subsequently produced.
“The findings of this investigation indicate that mercury concentration in the waters of the Port Kaituma River, near the GWI Pump Station, were not appreciable when compared to international guidelines for drinking water quality,” the report noted in its conclusion.
It said that with respect to the mercury analysis done on the river water samples, it was found that at all sample points the concentrations were within the WHO guideline of 0.006 mg/L with the concentrations ranging from 0.000016 mg/L to 0.000219 mg/L. The average concentration recorded was 0.0000761 mg/L.
Even when measured against the drinking water Maximum Contaminant Level (MCL) – 0.002mg/L – that is enforced by the United States Environmental Protection Agency (USEPA), it was found that all sample points were within the standard.
The report also noted that while the Canadian interim sediment quality guideline (ISQG), also known as threshold effects level (TEL), and the probable effects level (PEL) for mercury in fresh water sediment are 0.174 and 0.486 mg/kg dry weight, respectively, when examined, four samples were found to exceed the guideline value. However, all concentrations were below the PEL level.
This means that while the quality of the water was found to be safe, there were “high enough” levels of mercury contamination of the river sediment suggested by the findings to indicate that there may be some effect on the aquatic species in the area.
Given the overall findings of the research, it was recommended that “Officers assigned to the mining districts should undertake, where relevant, to ensure that sample points at and near pump stations or known water sources are included in their routine water quality monitoring. Further, the Environmental Division should endeavour to lead investigations to ascertain the status of rivers/creeks within mining districts where GWI pump stations are located and where contamination from mining operation poses an imminent threat to the community.”
In terms of the methodology used to conduct the investigation, the report noted that a reconnaissance survey starting at the confluence of the Kaituma Canal and the Kaituma River, also known as Pump Creek, and ending at the Walabaka Creek was first conducted on July 26, and was done in order to ascertain whether there was any influence of mining in the river and to establish sample locations.
After the survey was done, 11 sample points were selected and five team members were involved in collecting samples of water and sediment to be analysed for the presence of mercury, arsenic, cadmium and lead.
One sediment sample was taken at each of the 11 sample points using the Ekman grab sampler, while two water samples were taken at each point (for a total of 22 water samples). Those samples were delivered to the Kaizen Environmental Services.
An additional five water samples for mercury had also been collected and were sent to the Act Lab last month.
For the other heavy metals – Arsenic, Cadmium and Lead – nothing unusual was found as the results of the tests showed that all three were well within the normal levels.
