Lischeid, G; Moritz, K; Bittersohl, J; Alewell, C; Matzner, E: Sinks of anthropogenic nitrogen and sulphate in the Lehstenbach catchment (Fichtelgebirge): lessons learned concerning reversibility., Silva Gabreta, 4, 41-50 (2000)
Abstract: The Lehstenbach Catchment Study in the Fichtelgebirge region was one of many set up in 1987 to investigate the impact of sulphur and nitrogen emissions on soil, groundwater and reshwater quality. Sulphate immissions as determined by throughfall decreased by 50% down to 1 kmol ha-1 a-1 in the last 12 years. So far, recovery seems to be restricted to the top soil layers, whereas sulphate accumulation still continues in the deeper layers of the aquifer. Based on the analysis of nine cores of 10 m depth, the total sulphate pool in this layer is estimated to be about 90 kmol ha-1. This pool is clearly reversibly bound. Its dynamics can be described by desorption isotherms. For nitrogen, export via the catchment runoff and net uptake by plants accounts for only one third of the total nitrogen sink. Redox processes have been shown to occur locally. However, this seems to be only a minor sink for both sulphur and nitrogen at the catchment scale. Instead, there is strong evidence that a substantial proportion of the nitrogen in the catchment is bound by adsorption to the solid phase in the deeper layers of the aquifer. This process is at present not well understood.