Establishing ecological reference conditions and tracking post-application effectiveness of lanthanum-saturated bentonite clay (Phoslock®) for reducing phosphorus in aquatic systems: an applied paleolimnological approach.
Innovative management strategies for nutrient enrichment of freshwater are important in the face of this increasing global problem, however many strategies are not assessed over long enough time periods to establish effectiveness. Paleolimnological techniques using diatoms as biological indicators were utilized to establish ecological reference conditions, environmental variation, and the effectiveness of lanthanum-saturated bentonite clay (brand name: Phoslock(®)) applied to reduce water column phosphorus (P) concentrations in four waterbodies in Ontario, Canada, and eastern Australia. In sediment cores from the two Canadian sites, there were short-lived changes to diatom assemblages, relative to inferred background conditions, and a temporary reduction in both measured and diatom-inferred total phosphorus (TP) before returning to pre-application conditions (particularly in the urban stormwater management pond which has a high flushing rate and responds rapidly to precipitation and surface run-off). The two Australian sites (a sewage treatment pond and a shallow recreational lake), recorded no reduction in diatom-inferred TP. Based on our pre-application environmental reconstruction, changes to the diatom assemblages and diatom-inferred TP appeared to be driven by larger, climatic factors. While laboratory tests involving this product showed sharp reductions in water column TP, management strategies require detailed information on pre-application environmental conditions and variations in order to accurately assess the effectiveness of new technologies for lake management.
Lake Simcoe Region Conservation Authority, 120 Bayview Parkway, Newmarket, Ontario, Canada L3Y 3W3. Electronic address: melissa.t.moos@gmail.com.
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Moos
Southern Cross Geoscience and School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
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Taffs
Lake Simcoe Region Conservation Authority, 120 Bayview Parkway, Newmarket, Ontario, Canada L3Y 3W3.
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Longstaff
Lake Simcoe Region Conservation Authority, 120 Bayview Parkway, Newmarket, Ontario, Canada L3Y 3W3.
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Ginn
D000538:Aluminum Silicates / Q000737:chemistry; D001546:Bentonite / Q000737:chemistry*; D000077215:Clay; D017377:Diatoms; D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments / Q000032:analysis; D060106:Lakes; D007811:Lanthanum / Q000737:chemistry*; D009517:New South Wales; D009864:Ontario; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D011793:Queensland; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D014876:Water Pollution / Q000517:prevention & control; D018508:Water Purification / Q000379:methods*
D000538:Aluminum Silicates; D014874:Water Pollutants, Chemical; D001546:Bentonite; D010758:Phosphorus; D007811:Lanthanum; D000077215:Clay
Australia; Diatoms; Lake Simcoe; Phoslock(®); Phosphorus; Ponds