Epsilon Archive for Student Projects

Abstract

The presence of arsenic in soil and water has become an increasing problem in many countries around the world. The exposure of high concentration of arsenic in its inorganic form in natural environment such as soil and water makes it harmful to both humans, wildlife and plants. This study considered the possibility of phytoremediation as a management tool for abandoned sites moderately contaminated with arsenic with the aim of reducing its spread and eventual leaching of the contaminant into the groundwater. Focus was placed on Salix tree crops with phytoremediation abilities in relation to arsenic contamination in Sweden. These sites are termed abandoned because they are of less priority for public funding for remediation and total cleanup. Using a theoretical framework, this study was carried out by searching, screening and reviewing of scientific publications of previous studies and reports. An economic benefit calculation was done using surveys carried out on few Salix plantations in Sweden, where the farmers were asked about the cost of production and how much revenue was generated from the sale of the harvested biomass for energy purposes. The results showed that Salix has the potential to effectively phytostabilize arsenic in Sweden as the tree crop is known to preferably/actively accumulate arsenic in its roots and belowground biomass which is a key feature of Phytostabilization. In addition to its Phytostabilization capabilities, Salix has a good biomass production ability, producing woody biomass at a range of 7 – 10 tonnes of dry matter/ha/year regardless of the soil condition or quality as Salix has a good physiological adaptation mechanism and ecological resilience which helps them thrive in various climate zones and site conditions coupled with their rapid woody biomass production ability as a short rotation coppice. The economic benefit calculations revealed that private remediation firms can invest in the remediation of these abandoned sites and still generate revenue of as much as 8,000 – 10,000 SEK/ha/year and make a reasonable profit of up to 57% through the sale of the harvested woody biomass to energy producing plants. These woody biomass has little or no arsenic accumulated in them because the accumulation of arsenic is in the root of the Salix tree, thereby meeting the quality requirement for energy production From the survey used for calculating potential profit generated from the cultivation of Salix, the Salix plantations studied were cultivated on agricultural soils with good soil quality. Therefore they produced woody biomass with an average of 9 tonnes of dry matter/ha/year. Nevertheless, it was feasible to relate the cultivation of Salix and biomass yield produced by Salix on an agricultural soil to those cultivated on brown fields or soils with poor quality as the findings in this study showed that the quality or condition of soils does not significantly affect the biomass production and yield of Salix tree crops.