SCREENING II 2017-2019

The duration of the project was from 1 March 2017 until 28 February 2019.

The project was implemented by Novia University of Applied Sciences.

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

Goal

The first goal of the project was to screen the geochemical and microbial effect of ultra-fine grained limestone powder (2.5 µm in diameter, Nordkalk´s product C2) and precipitated calcium carbonate (0.3 µm in diameter, Nordkalk´s product Enrich Bio) and of electron donors (such as peat and various peat degradation products) on acid sulfate soil. The results from the project were used to choose which treatments to test on a larger field scale. The second goal of the project was to characterize the overall structure and function of the microbial community in the acid sulfate soil, in the transition zone, as well as in the original sulfide sediment.

Measures
The various treatments of the acid sulfate soil in the screening trial were manual mixing of 1) 1 % ultrafine-grained limestone powder (Enrich Bio) 2) 1 % mixture of equal parts peat (H1 level) and ultrafine-grained limestone powder (C2) 3) 1 % mixture of equal parts peat (H5 level) and ultrafine-grained limestone powder (C2) 4) 0.1 % sodium acetate and 5) 0.1 % natriumlactate 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.

For the microbiological characterization, soil samples were taken in triplicate from the acid sulfate soil, the transition zone and the original sulfide sediment at the Risöfladan experimental field. DNA and RNA were isolated from all soil samples and sent to the U.S. Department of Energy Joint Genome Institute (JGI) for metagenomic (DNA) and metatranscriptomic (RNA) sequencing. In addition to the sequencing data generated by JGI, a 16S rRNA gene sequencing was performed on DNA isolated from the soil samples. Geochemical analyses were also performed on the soil samples in the form of pH, conductivity and redox measurements, sulfur and iron speciations and analyzes of selected metals.

Funding