Letter to the Editor pubs.acs.org/est
Response to the Letter, “Nitrogen is Not a “House of Cards”
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In response to the comment on our paper1 by James Cotner, we would like to clearly state our main points. A large number of well-documented whole-lake trials show that phosphorus abatement mitigates eutrophication. There are no cases where whole-lake nitrogen abatement has mitigated eutrophication, but there is one well-documented case where N abatement made eutrophication worse. There are many reasons to reduce N pollution of the environment, but lake and reservoir eutrophication are not among them. There is no contradiction in our recommendation not to reduce point sources of nitrogen to lakes, but to reduce the element in atmospheric deposition and land application. Simply put, there is ecosystem evidence that nitrogen damages soils and groundwaters, whereas the rationale for controlling nitrogen in freshwater is based solely on short-term, small scale studies, none of them at long-term ecosystem scales. It is this latter body of work, not the problem of overall nitrogen pollution, that we call “A House of Cards.” We agree that nonpoint P pollution is the major driver of eutrophication in regions where industrialized agriculture is a major land use. However, eutrophication is increasing because policies and practices for nonpoint pollution control are failing to decrease P inputs.2−6 Better policies and practices for reducing nonpoint P pollution are the key to reducing eutrophication.
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D. W. Schindler* S. R. Carpenter S. C. Chapra R. E. Hecky D. M. Orihel AUTHOR INFORMATION
Notes
The authors declare no competing financial interest.
REFERENCES
(1) Schindler, D. W.; Carpenter, S. R.; Chapra, S. C.; Hecky, R. E.; Orihel, D. M. Reducing Phosphorus to Curb Lake Eutrophication is a Success. Environ. Sci. Technol. 2016, 50, 8923. (2) Hamilton, S. K. Biogeochemical time lags may delay responses of streams to ecological restoration. Freshwater Biol. 2012, 57, 43−57. (3) Shortle, J. S.; Ribaudo, M.; Horan, R. D.; Blandford, D. Reforming Agricultural Nonpoint Pollution Policy in an Increasingly Budget-Constrained Environment. Environ. Sci. Technol. 2012, 46 (3), 1316−1325. (4) Lathrop, R. C.; Carpenter, S. R. Water quality implications from three decades of phosphorus loads and trophic dynamics in the Yahara chain of lakes. Inland Waters 2014, 4, 1−14. (5) Rissman, A. R.; Carpenter, S. R. Progress on nonpoint pollution: Barriers and opportunities. Daedalus 2015, 144, 35−47. (6) Garnache, C.; Swinton, S. M.; Herriges, J. A.; Lupi, F.; Stevenson, R. J. Solving the Phosphorus Pollution Puzzle: Synthesis and Directions for Future Research. American Journal of Agricultural Economics 2016, 98 (5), 1334−1359. Received: December 9, 2016 Accepted: December 11, 2016
© XXXX American Chemical Society
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DOI: 10.1021/acs.est.6b06106 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
