The fate of inorganic colloidal particles in Lake Brienz

Abstract

Abstract. The fate of colloidal particles in Lake Brienz and its two main tributaries, the Aare and Lütschine Rivers, was studied over a period of more than a year. Lake colloid loads from the unmodified Lütschine fluctuated significantly across seasons. The highest loads are in summer due to glacier melting. Colloid loads from the Aare reflected the seasonal water use by upstream hydropower plants. A significant number of mineral particles, even outside the theoretical nonsettling range, remain in suspension in the epilimnion of Lake Brienz in summer because of the mineralogical nature and shape of the particles and the high input loads. Only 1730 of the 16,800 tons of colloidal particles that entered the lake during the period from 1 June 2004 -31 July 2005 were exported through the lake outlet. The remainder was presumably lost in the lake through coagulation-sedimentation processes. Coagulation properties of non-fractionated colloid samples in quiescent conditions were studied in the laboratory both in the absence and presence of different organic compounds representative of natural organic matter. Lake Brienz colloids coagulate slowly, as expected from particles (mainly phyllosilicates) bearing a net negative surface charge. Slightly higher coagulation rates were recorded in March and April during the spring algal bloom, which suggests that colloid coagulation is enhanced by carbohydrates. This effect was confirmed in laboratory experiments. However, the concentration of natural organic matter in Lake Brienz is so low that it is not having any significant effect on the fate of inorganic colloids.

Evolution of the physico-chemical water quality in the Nam Theun 2 Reservoir and downstream rivers for the first 5 years after impoundment

“…Otherwise, load is estimated by multiplying the flow weighted average concentration by the mean flow over the relevant period. A more detailed description of the procedure is available in Chanudet & Filella (2007).…”

Size and composition of inorganic colloids in a peri-alpine, glacial flour-rich lake

“…Otherwise, load is estimated by multiplying the flowweighted average concentration by the mean flow over the relevant period. A more detailed description of the procedure is available in Chanudet and Filella (2007a).…”

“…This investigation was undertaken within the framework of a larger project which aimed to understand the reasons for the ultra-oligotrophic status of the lake (Wü est et al, 2007). The fate of the submicron organic matter present in the system has been the subject of a parallel study (Chanudet and Filella, 2007a).…”

Effects of Alpine hydropower dams on particle transport and lacustrine sedimentation

“…Several aspects of the Grimsel-Brienz source-sink system were studied. One possible scenario was that the amount and timing of suspended particles (Finger et al, 2006) and colloids (Chanudet and Filella, 2007) released to Lake Brienz changed over time with direct consequences on water clarity. All of these parameters might have furthermore affected the availability of nutrients (Müller et al, 2007a), primary production , the Daphnia population and fish ecology (Müller et al, 2007b).…”