SCREENING I 2016

The duration of the project was from 16 February until 31 December 2016.

Project partners were Novia University of Applied Sciences, Vaasa University of Applied Sciences, Åbo Akademi University and YA - Vocational College of Ostrobothnia.

The microbiological evaluation of the experiment was done in corporation with the Linnaeus University in Kalmar, Sweden.

The goal of the project was to screen, in smaller laboratory scale and for a shorter time, the mixture of ultrafine-grained limestone powder (2.5 μm in diameter, Nordkalk C2), very fine-grained peat (4–8 μm in diameter, Vapo Oy) and a combination of these in acid sulfate soil to investigate what effect the treatments have on the metal and acid leaching and on the bacterial community in mixed soil both in oxygen-rich and oxygen-free environments. The role of the limestone powder was to increase the pH value in the soil and the role of the peat was to act as an antioxidant and as an energy source for the bacteria in the soil. The results from the project were used to choose which treatments to test on a larger field scale.

Measures
The different treatments of the acid sulfate soil were manual mixing of 1) 1% ultrafine-grained limestone powder 2) 1% fine-grained peat and 3) 1% mixture of equal parts limestone powder and peat per dry weight soil. As a control, untreated soil was used. To investigate the oxygen influence of the treatments, all samples were prepared in both oxygen-free and oxygen-rich environments. The treated soil samples were stored at 10°C in the dark for 10 weeks. After storage, the pH and conductivity from the samples were measured and, in addition, sulfur and iron speciations and analysis of metals were performed for the geochemical evaluation. For the microbiological evaluation, DNA was isolated from the bacterial cells in the soil and a 16S rRNA sequencing was performed to identify the bacterial populations.

Funding