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Influence of coupling of sorption and photosynthetic processes on trace element cycles in natural waters

January 1, 1989

Chemical and biological processes have important roles in the transport and cycling of trace elements in natural waters, but their complex interactions are often not well understood. Trace-element concentrations may, for example, be controlled by adsorption-desorption reactions at mineral surfaces, with the equilibrium strongly influenced by pH. Variations in pH due to photosynthetic activity should result in concentration fluctuations as the adsorption-desorption equilibrium shifts with pH. To investigate these interactions, we have studied the effect of diurnal cycling of pH on dissolved arsenate in a perennial stream contaminated with arsenic. As expected, a diurnal cycle in arsenate concentration was observed, but surprisingly, the arsenate cycle lags several hours behind the pH cycle. Laboratory experiments show that the lag results from a slow approach to sorption equilibrium. Our observations demonstrate that the coupling of photosynthesis and sorption processes may have an important influence on the cycling of many trace elements and emphasize the importance of understanding sorption kinetics in modelling these processes.

Citation Information

Publication Year 1989
Title Influence of coupling of sorption and photosynthetic processes on trace element cycles in natural waters
DOI 10.1038/340052a0
Authors C. C. Fuller, J.A. Davis
Publication Type Article
Publication Subtype Journal Article
Series Title Nature
Index ID 70015895
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program