| dc.description.abstract | Acid sulphate soils have been referred to as being among the most harmful soils in the world
due to their ability to severely decrease the pH of the water, consequently enabling an increased
metal load to recipient water streams, lakes, groundwater reservoirs and estuaries. The presence
of acid sulphate soils has triggered several fish kill episodes in northern Scandinavia and the
soils are today threatening many of the national environmental goals of Sweden. Their
widespread coverage in northern Sweden and western Finland have endorsed these regions to
be the focal point for previous investigations. However, in early 2019, acid sulphate soils were
discovered in Halland, SW Sweden and this study therefore aimed to investigate the impact
from these non-investigated soils on the surface water chemistry of an affected area. This was
conducted through in situ surface water sampling from two areas, in order to cover both smaller
ditches (area 1) and a larger canal (area 2), located adjacent to a confirmed acid sulphate soil.
Sampling was conducted during three separate occasions; autumn, winter and spring with the
purpose of investigating differences in discharge depending on season. Water pH and electric
conductivity was determined in situ, and the total metal compositions of Al, As, Cd, Co, Cr,
Cu, Fe, Mn, Ni, Pb, V and Zn was analysed with an ICP-MS instrument. Additionally,
groundwater data was collected to determine potential impact on the drinking water of the
region. The results provide strong indications of leakage from the acid sulphate soils into the
surface water, visible through elevated metal concentrations along with pH values between 3.8
and 6.6. Additionally, high electric conductivity values were measured in the water (32-129
mS/m) implying high SO4
2- composition in the water. Higher metal concentrations and lower
pH values were measured in area 1 compared to area 2, hence assumed to be more influenced
by the adjacent sulphuric soil layer. The metal concentrations in the water decreased from
autumn to spring, likely reflecting the high temperatures and prolonged precipitation in Halland
2019/2020, further implying the importance of considering climatic parameters when
investigating acid sulphate soil leaching. No indications of contaminated groundwater were
seen in the results; however, no definite conclusions could be drawn due to limitations in the
dataset. The study site was further compared to other sites in Sweden and Finland, where
indications of slightly lower discharge were seen in Halland. | sv |
