Odorous Substances and Cyanobacterial Toxins in Prairie Drinking Water Sources

Abstract

Algal blooms in eutrophic lakes have been regarded by some as primarily an aesthetic nuisance for recreational and drinking water uses despite well documented incidents of livestock and wildlife poisoning attributed to cyanobacterial toxins. A survey was conducted of three eutrophic, water supply lakes and eight rural dugouts experiencing cyanobacterial blooms. Biomass was characterized for dominant cyanobacterial genera and analyses were conducted for the hepatotoxins, microcystin LR and RR and the neurotoxin, anatoxin-a. Some water samples collected simultaneously were screened for geosmin, 2-methylisoborneol and β-cyclocitral. Results showed that microcystin LR (LD50 of 50 µg/kg in mice) was present in concentrations up to 500 µg/g of algal biomass and microcystin LR levels were generally related to the proportion of Microcystis in the collected algal biomass. There was no relationship between the presence of microcystin LR and the presence of any of the odour compounds. Consequently, cyanobacterial odour-causing compounds in water did not provide reliable warning of the presence of the microcystin LR in these cyanobacterial blooms.

Biochemical and Ecological Control of Geosmin and 2-Methylisoborneol in Source Waters

“…Planktothrix aghardhii), only brackish water clones produced geosmin and 2-MIB, indicating that salinity per se does not preclude the biosynthesis of these terpenoids. Along the same lines, geosmin and 2-MIB outbreaks are common problems in many areas of the North American prairies, where the presence of an ancient seabed results in highly saline and productive surface waters (46,99). …”

“…More long-term proactive management needs to address the source(s) of the problem, by identifying the environmental and biological agents and their controls (99,101). A significant proportion of odor events are linked to intense runoff from highly developed watersheds (37,47,113) and/or source water degradation and eutrophication (39,45,46,100) and the associated increase in odor-producing biota such as cyanobacteria. Clearly, therefore, ecologically sound watershed and source water remediation and management is essential to the long-term effectiveness and sustainability of a successful mitigation program.…”

Biological origins and annual variations of earthy-musty off-flavours in the Xionghe Reservoir in China

“…Planktonic and periphytic cyanobacteria, as well as some actinomycetes, produce 2-MIB and geosmin in reservoirs, lakes, fish ponds, rivers, canals and within water treatment plants (WTPs) (Gerber & Lechevalier 1965;Izaguirre & Taylor 1995;Suffet et al 1995;Jü ttner & Watson 2007). However, subsequent studies focused on cyanobacteria, which are the dominant group in eutrophic waters, particularly in summer as the main biological origin of earthy-musty off-flavours (Kenefick et al 1992;Jones & Korth 1995;Izaguirre et al 1999;Vilalta et al 2004).…”

Cyanobacterial toxins in Canadian freshwaters: A review

“…Drinking water treatment processes may also be adversely affected. Geosmin, 2-methylisoborneol and β-cyclocitral are non-toxic, odorous substances produced by cyanobacteria (Kenefick et al 1992) that can impart taste and odor to finished drinking water, making effective treatment of tainted source waters more challenging and expensive. Similarly, trihalomethanes are toxic by-products resulting from chlorine-based disinfection of water containing high levels of dissolved organic matter (i.e., algae and cyanobacterial cellular debris) (Palmstrom et al 1988).…”