title: Sediment amendment with Phoslock® in Clatto Reservoir (Dundee, UK): Investigating changes in sediment elemental composition and phosphorus fractionation.
abstract: Lanthanum-modified bentonite clay (Phoslock(®) is a lake remediation tool designed to strip dissolved phosphorus (P) from the water column and increase the sediment P-sorption capacity. This study investigated short term alterations in sediment elemental composition and sediment P-fractions based on sediment cores taken 2 days before and 28 days following the application of 24 t of Phoslock® to a 9 ha, man-made reservoir. Following the application, sediment lanthanum (La) content increased significantly (p < 0.05; n = 4) in the top 8 cm of the sediment, thereby theoretically increasing sediment P-binding capacity on the whole reservoir scale by 250 kg. Mass balance calculations were used to estimate the theoretical binding of release-sensitive P (P(mobile); sum of 'labile P', 'reductant-soluble P' and 'organic P' fraction) by La across the top 4 cm and 10 cm depth of sediment. The amended mass of La in the sediment had the potential to bind 42% of P(mobile) present in the top 4 cm or 17% of P(mobile) present in the top 10 cm. However, with the exception of a significant increase (p<0.05; n=4) in the 'residual P' fraction in the top 2 cm, sediment P-fractions, including P(mobile,) did not differ significantly following the Phoslock® application. Experimental P-adsorption studies indicated P-saturation values for Phoslock® of 21,670 mg P kg⁻¹ Phoslock®. Sequential extraction of P from saturated Phoslock® under laboratory conditions indicated that around 21% of P bound by Phoslock® was release-sensitive, while around 79% of bound P was unlikely to be released under reducing or common pH (5-9) conditions in shallow lakes. Applying Phoslock® is, therefore, likely to increase the P-sorption capacity of sediments under reducing conditions.
authors: Centre for Ecology & Hydrology, Penicuik, Midlothian, Scotland EH26 0QB, UK. sebisa@ceh.ac.uk
authors: Sebastian
authors: S
authors: Meis
authors: Bryan M
authors: BM
authors: Spears
authors: Stephen C
authors: SC
authors: Maberly
authors: Michael B
authors: MB
authors: O'Malley
authors: Rupert G
authors: RG
authors: Perkins
mesh_terms: D000042:Absorption; D000538:Aluminum Silicates; D001546:Bentonite; D005591:Chemical Fractionation; D000077215:Clay; D052918:Environmental Restoration and Remediation / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes; D007811:Lanthanum / Q000032:analysis / Q000737:chemistry; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry; D012606:Scotland; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D014874:Water Pollutants, Chemical; D001546:Bentonite; D010758:Phosphorus; D007811:Lanthanum; D000077215:Clay