Characterization of Organic Phosphorus Form and Bioavailability in Lake Sediments using 31P Nuclear Magnetic Resonance and Enzymatic Hydrolysis. Issue 3 (1st May 2015)

• Record Type: Journal Article
• Authors: Giles, Courtney D.; Lee, Lydia G.; Cade‐Menun, Barbara J.; Hill, Jane E.; Isles, Peter D. F.; Schroth, Andrew W.; Druschel, Gregory K.
• Is Part Of: Journal of Environmental Quality. Volume 44:Issue 3(2015)
• Page Start: 882
• Page End: 894
• Publication Date: 2015-05-01
• Subjects: Agricultural ecology -- Periodicals; Environmental engineering -- Periodicals; Pollution -- Periodicals; 630
• DOI: 10.2134/jeq2014.06.0273
• Languages: English
• ISSNs: 0047-2425

Abstract

Abstract : Lake sediments are known to be a significant source of phosphorus (P) to plankton populations under certain biogeochemical conditions; however, the contribution of sediment organic P (Porg ) to internal P loads remains poorly understood. We investigated Porg speciation and bioavailability in sediments collected over multiple months from a shallow, eutrophic bay in Lake Champlain (Missisquoi Bay, VT) using solution 31 P nuclear magnetic resonance (NMR) spectroscopy and enzymatic hydrolysis (EH) analysis of sediments collected during years with (2008) and without (2007) algal blooms. Sediments collected during bloom onset (July) and peak bloom (August) months contained the largest proportion of enzyme‐labile P, whereas pre‐ and postbloom sediments were primarily composed of nonlabile P. Monoester P to diester P ratios changed with respect to depth, particularly during bloom periods. Monoester P and DNA accumulation, likely from settling particulate matter, began at the onset of the bloom and continued into October 2008 during the postbloom period. The disappearance of inositol hexakisphosphate stereoisomers and the generation of orthophosphate at lower sediment depths was also evident in August 2008. Principal components analysis of EH and NMR species proportions confirmed differences between sediment cores collected during bloom onset and peak bloom, compared with pre‐ and postbloom sediments. Large enzyme‐labile and Porg species proportions corresponded to increased sediment P flux and reduced manganese and iron species in porewater. These findings suggest that interseasonal changes in Porg speciation may influence P mobility in sediments and contribute to important feedback dynamics between biological productivity and sediment water interface geochemistry.