| Title | The relative roles of point and nonpoint phosphorus sources in the eutrophication of Lake Champlain as recorded in sediment cores |
| Abstract | Thirteen sediment cores from Lake Champlain (Vermont-New York-Quebec) were analyzed for sediment accumulation rate and eleven indicators of trophic status to reconstruct eutrophication history and relate it to phosphorus inputs from soil erosion, urban point sources, and agricultural runoff including P extracted from phosphate ore and brought to the catchment in fertilizer and livestock feed. Although the catchment was severely deforested and grazed by sheep and cattle in the 19th century, ten of thirteen sites accumulated excess sediment only in the 20th century, a consequence of slow sediment transport through the catchment. Of the three sites that received extra sediment, one remained oligotrophic, while two exhibited mild eutrophication. All sites underwent eutrophication in the 20th century. Three reached their current trophic status before agriculture's intensification, while point-source P input was maximal (1950-1980), four stayed in the reference state until agriculture intensified in the 1970s, and six responded incrementally first to point and then to agricultural P input. Pigment accumulation rates diminished at the surface of seven cores, evidence that the 1990s expansion of P removal from point sources reduced phytoplankton biomass. Additional water quality improvement depends on P management at the catchment border to balance inputs and outputs, and thus avoid P accumulation in soil that saturates phosphate sorption capacity, increasing the proportion of runoff P that is highly-bioavailable orthophosphate. Erosion control is of lower priority because the P native to the catchment's soil is of relatively low bioavailability, and retention structures do not retain dissolved P. (C) 2018 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. |
| Source | Journal of Great Lakes research 44 (5), pp. 1043–1056 |
| Keywords | Lake ChamplainEutrophicationPaleolimnologyAgricultureSedimentRestoration |
| Journal | Journal of Great Lakes research |
| Editor | International Association for Great Lakes Research., s.l., Canada |
| Year | 2018 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.jglr.2018.06.005 |
| Authors | Levine, Suzanne N.; Lini, Andrea; Ostrofsky, Milton L.; Burgess-Grant, Heather; Lami, Andrea; Collyer-Gilles, Elizabeth; Reuter, Daun; Schwarting-Miller, Lindsay; Kamman, Neil |
| Text | 407832 2018 10.1016/j.jglr.2018.06.005 ISI Web of Science WOS 000447818500023 Lake Champlain Eutrophication Paleolimnology Agriculture Sediment Restoration The relative roles of point and nonpoint phosphorus sources in the eutrophication of Lake Champlain as recorded in sediment cores Levine, Suzanne N.; Lini, Andrea; Ostrofsky, Milton L.; Burgess Grant, Heather; Lami, Andrea; Collyer Gilles, Elizabeth; Reuter, Daun; Schwarting Miller, Lindsay; Kamman, Neil Univ Vermont; Univ Vermont; Allegheny Coll; CNR; Paul Smiths Coll; Vermont Agcy Nat Resources Thirteen sediment cores from Lake Champlain Vermont New York Quebec were analyzed for sediment accumulation rate and eleven indicators of trophic status to reconstruct eutrophication history and relate it to phosphorus inputs from soil erosion, urban point sources, and agricultural runoff including P extracted from phosphate ore and brought to the catchment in fertilizer and livestock feed. Although the catchment was severely deforested and grazed by sheep and cattle in the 19th century, ten of thirteen sites accumulated excess sediment only in the 20th century, a consequence of slow sediment transport through the catchment. Of the three sites that received extra sediment, one remained oligotrophic, while two exhibited mild eutrophication. All sites underwent eutrophication in the 20th century. Three reached their current trophic status before agriculture s intensification, while point source P input was maximal 1950 1980 , four stayed in the reference state until agriculture intensified in the 1970s, and six responded incrementally first to point and then to agricultural P input. Pigment accumulation rates diminished at the surface of seven cores, evidence that the 1990s expansion of P removal from point sources reduced phytoplankton biomass. Additional water quality improvement depends on P management at the catchment border to balance inputs and outputs, and thus avoid P accumulation in soil that saturates phosphate sorption capacity, increasing the proportion of runoff P that is highly bioavailable orthophosphate. Erosion control is of lower priority because the P native to the catchment s soil is of relatively low bioavailability, and retention structures do not retain dissolved P. C 2018 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. 44 Published version Articolo in rivista International Association for Great Lakes Research. 0380 1330 Journal of Great Lakes research Journal of Great Lakes research J. Great Lakes res. andrea.lami LAMI ANDREA |
