干旱区生态环境知识资源中心

This paper presents the first systematic investigation of stable isotopes (delta O-18 and delta H-2) from the subfossil chironomid head capsules (HCs) of a single taxon (Chironomus). The study focuses on sixteen south-eastern Australian lakes and investigates the potential of Chironomus spp. HC stable isotopes to reconstruct past temperature changes from these lakes. The relationship between delta O-18 values of Chironomus spp. HCs from Australian oligotrophic to mesotrophic lakes in humid areas and air temperature appears robust (r = 0.88) and in line with results from European lakes. Similar results were obtained for delta H-2 values and temperature (r = 0.94). For lakes that are located in semi-arid and sub-humid areas that have high evaporation compared to precipitation, and often long water residence time, the temperature relationship is not robust. This is due to the evaporative enrichment of delta O-18 values in lake water and the effect of salinity and higher nutrient status. Vital effects may also play a role. The overall findings of this study are that both Chironomus spp. HC delta O-18 and delta H-2 are potentially valuable tools for reconstructing temperature in cooler, low nutrient and low salinity lakes of Australia. In warmer, sub-humid to semi-arid regions, delta O-18 and delta H-2 may provide valuable information about past changes in hydrological conditions.