Production and Reduction of Geosmin and 2-Methylisoborneol During Storage of River Water in Deep Reservoirs

Abstract

The Water Storage Corporation Brabantse Biesbosch manages three interconnected deep reservoirs in the south western part of The Netherlands. These reservoirs, with a total retention period of five to six months, are employed for storage and upgrading of polluted and eutrophic water from the River Meuse. In the first two reservoirs, with a total retention period of 4-5 months, probably due to adsorption/settling and biodegradation there is a reduction of geosmin and 2-methylisoborneol (2-MIB) down to 1-2 ng/l, i.e. 60-70% of the concentration in the river water. In the last reservoir Petrusplaat a large benthic cyanobacterial population consisting of various Oscillatoriaceae produces geosmin from February till June. In 1984 this production resulted in an average concentration of 6 ng/l, i.e. 5-6 times the concentration of the inlet of this reservoir. Since 1985 cyanobacterial growth is controlled by rooting up the bottom with a harrow. This resulted in average concentrations of 1-3 ng/l, i.e. twice the average concentration of the inlet. No further reduction of 2-MIB has been observed in this reservoir. It is concluded that storage of eutrophic river water in deep reservoirs reduces the concentration of geosmin and 2-MIB. Autochthonous production however may interfere with this water quality improvement.

Downstream Transport of Geosmin Based on Harmful Cyanobacterial Outbreak Upstream in a Reservoir Cascade

“…The GSM concentration was higher in the reservoirs (5–7100 ng L −1 ) and shallow water than in the streams (4–24 ng L −1 ), with a high frequency and extent of the Dolichospermum bloom ( Appendix A ). Generally, the GSM concentrations in the reservoirs decreased (60–70% of influent water) primarily because of adsorption, sedimentation, and biodegradation (3.1 ng L −1 d −1 ), as described in a previous study [ 25 ]. However, if internal productivity is high (e.g., dense bloom) because of aggravated anthropogenic pollution factors, efforts to improve water quality may have adverse effects, which is intensified in eutrophic water bodies with shallow water depths [ 25 ].…”

“…Generally, the GSM concentrations in the reservoirs decreased (60–70% of influent water) primarily because of adsorption, sedimentation, and biodegradation (3.1 ng L −1 d −1 ), as described in a previous study [ 25 ]. However, if internal productivity is high (e.g., dense bloom) because of aggravated anthropogenic pollution factors, efforts to improve water quality may have adverse effects, which is intensified in eutrophic water bodies with shallow water depths [ 25 ]. In addition, GSM in stratified reservoirs with discharge systems in deep layers (middle or bottom) are mostly concentrated just below these layers, and effluents after destratification by turnover can hinder water use for several months [ 83 ].…”

“…To determine the decrease and fate of the GSM released into the water body of a reservoir, the water is subjected to various phenomena, such as adsorption, sedimentation, photolysis, volatilization, animal feeding, biodegradation, dispersion, and dilution [ 25 , 83 ]. The GSM between the Euiam and Paldang Reservoirs was most likely to be delivered to the downstream reservoir after the rainy season and introduced into the hydropower effluent, which was the only transport mechanism [ 43 , 84 ].…”

“…This deteriorates the water quality, even resulting in public complaints and countermeasures. Moreover, this acts as a social risk factor by aggravating the economic burden and inconvenience in daily life activities [ 3 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ].…”

Geosmin and MIB events in a new reservoir in southern California

“…In view of the history of O. limosa with respect to MIB problems, it is reasonable to consider it a potential source of MIB in DVL also. Other investigators have reported geosmin from this species (Van Breemen et al, 1992;Durrer et al, 1999;Sabater et al, 2003), but it is uncertain whether they all referred to the same organism. Various studies in the last twenty years have implicated other attached cyanobacteria as sources of MIB or geosmin in lakes, reservoirs or rivers, including Burlingame et al (1986), Sugiura et al (1998), Watson and Ridal (2004) and Baker et al (2006).…”