Description:
AbstractTwo pairs of springs were surveyed in the floodplain of the Upper Rhône River. Each pair included a karstic (upstream) and an alluvial (downstream) spring in the same catchment. Various physical, chemical, and biological factors were measured in the water and the sediment. The study showed karstic and alluvial spring typology. In each pair, the karstic springs were characterized by higher alkalinity, whereas alluvial springs were fed both by karstic groundwater and Rhône River water with higher sulphate content.Organic matter dynamics and retention processes were different in each spring. The distribution and abundance of fine sediment played a prominent role in the storage of particulate organic carbon and the development of microbial biomass and activity. The hydrological cycle governed organic and inorganic nutrient fluxes, and was, with temperature, the main factor influencing microbial and macroinvertebrate dynamics. The high amount of organic matter in one alluvial spring was correlated with high microbial biomass and activity.