A laboratory study on the immobilisation of inorganic chlorine in soil
Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
Inorganic chlorine (Clinorg) is generally considered to be inert and has been used as a tracer for groundwater movements. This assumption is thereby fundamental for current knowledge about soil biogeochemistry. However, recent work showed that Clinorg can be retained, i.e. immobilised, in soil, which contradicts the previous assumptions. The aim of this laboratory study was to investigate if the processes that immobilise Clinorg in soil are affected by molecular oxygen (O2), and if the immobilisation occurs in the top soil layer only or also further down were the soil structure is different from the upper soil layer. Two experimental set-ups have been established. In the first experiment regarding the O2 regime (OXANIS), the immobilisation of Clinorg was studied in soil under oxic and anoxic conditions, respectively. In a second incubation study (SOLIS) the immobilisation was studied under oxic conditions in different layers of a coniferous forest soil. To investigate the immobilisation of Clinorg, a method using radiolabelled chloride 36 (36Clinorg) was applied. The use of radiolabelled chloride is an excellent and reliable method for studying transformation processes in soil systems. The results of the laboratory study showed that Clinorg retention rates under oxic conditions were much higher than retention rates under anoxic conditions, indicating an important role of O2. Furthermore, the immobilisation of Clinorg occurred in all soil layers were oxygen is provided, but rates were highest in the top soil layer (organic layer, O-horizon). Clearly, O2 influenced the net Clinorg retention, but additional studies are required to identify the processes behind this result. The calculated immobilisation rates for Clinorg in the three soil horizons correspond to the amount of organic material detected in the different soil horizons indicating a strong connection between the occurrence of organic matter in soil and the immobilisation of Clinorg.
Place, publisher, year, edition, pages
Institutionen för tema , 2006. , 24 p.
Chlorine, soil horizons, LSC, oxic, anoxic, 36Cl, natural processes, forest soil
IdentifiersURN: urn:nbn:se:liu:diva-7164ISRN: LIU-TEMA/MV-D--06/07--SEOAI: oai:DiVA.org:liu-7164DiVA: diva2:22226
2006-05-31, , Täppan, Norrköping, 08:00