A study which assessed heavy metals in the water collected from the mine sumps and bore-wells of an abandoned copper mine in Lasail, northern Oman, has found that the water is extremely acidic with very high electrical conductivity and high heavy metal concentrations. The study, conducted by researchers from Sultan Qaboos University (SQU), recommended proper remediation measures to cleanse the area to avoid further ground water contamination. The Lasail copper mine in northern Oman was one of the largest single ore deposits which operated from 1983 to 1994. The mine was abandoned in 1994, but large amounts of waste piles were left behind. The mine area includes two mine sumps and two open bore-wells. Water samples were collected in the months of July 2016 and January 2017 to represent summer and winter seasons.

The main objective of this study was to determine the water quality of this abandoned copper mine area by evaluating the composition and concentrations of heavy metals. Abandoned mining sites are largely responsible for the release of heavy metals into water systems. Thenmozhi M Palanivel, a PhD scholar in the Department of Biology at the College of Science at SQU, conducted this study under the supervision of Prof Reginald Victor.

The researchers assessed heavy metals in the water collected from the mine sumps and bore-wells. They evaluated the physicochemical parameters of the water using moder methodology. The results show that the waters are extremely acidic with very high electrical conductivity. Aluminium (Al), Boron (B), Copper (Cu), Iron (Fe), Mercury (Hg) Manganese (Mn) and Zinc (Zn) are in very high concentrations, well above the limits recommended by Oman and World Health Organization (WHO) standards.

The findings of this study have been published in the January-June 2019 issue of Inzynieria Mineralna, Journal of the Polish Mineral Engineering Society, under the title Water Pollution Assessment of an Abandoned Copper Mine in Lasail, Sultanate of Oman.

The study further says that industrial activities such as mining are highly responsible for the input of toxic elements into water systems. The toxic elements are released not only at the big mining sites, but also in places of artisanal mineral exploitation and abandoned mining sites. The adverse effects of abandoned mines are known to persist for decades, even after the decommissioning of mines, most often until the sulphides are completely weathered. Water is one of the vital compounds for all forms of life and hence water pollution receives considerably more attention when compared to soil and air.

Palanivel and Prof Victor said that the metals leach into groundwater and soil solution when their concentration exceeds the retention capacity of soils. Metals can be distinguished from other toxic pollutants, since they are non-biodegradable, and can be concentrated and accumulated throughout the food chain. The study also states that Acid Mine Drainage (AMD) is one of the major environmental impacts of sulphide mines. AMD is produced mostly when pyrite ore is left exposed on the surface and thus oxidized by a combination of water, oxygen and existing bacteria. It is characterised by extremely low pH values and high concentrations of heavy metal ions, which pollute large areas and surface/groundwater systems.

Source: Ministry of Information Sultanate of Oman