@article {2674,
	title = {{\textquotedblleft}New{\textquotedblright} cyanobacterial blooms are not new: two centuries of lake production are related to ice cover and land use},
	journal = {Ecosphere},
	volume = {11},
	year = {2020},
	month = {Jan-06-2020},
	abstract = {Recent cyanobacterial blooms in otherwise unproductive lakes may be warning signs of impending eutrophication in lakes important for recreation and drinking water, but little is known of their historical precedence or mechanisms of regulation. Here, we examined long-term sedimentary records of both general and taxon-specific trophic proxies from seven lakes of varying productivity in the northeastern United States to investigate their relationship to historical in-lake, watershed, and climatic drivers of trophic status. Analysis of fossil pigments (carotenoids and chlorophylls) revealed variable patterns of past primary production across lakes over two centuries despite broadly similar changes in regional climate and land use. Sediment abundance of the cyanobacteriumGloeotrichia,a large, toxic, nitrogen-fixing taxon common in recent blooms in this region, revealed that this was not a new taxon in the phytoplankton communities but rather had been present for centuries. Histories ofGloeotrichiaabundance differed strikingly across lakes and were not consistently associated with most other sediment proxies of trophic status. Changes in ice cover most often coincided with changes in fossil pigments, and changes in watershed land use were often related to changes inGloeotrichiaabundance, although no single climatic or land-use factor was associated with proxy changes across all seven lakes. The degree to which changes in lake sediment records co-occurred with changes in the timing of ice-out or agricultural land use was negatively correlated with the ratio of watershed area to lake area. Thus, both climate and land management appeared to play key roles in regulation of primary production in these lakes, although the manner in which these factors influenced lakes was mediated by catchment morphometry. Improved understanding of the past interactions between climate change, land use, landscape setting, and water quality underscores the complexity of mechanisms regulating lake and cyanobacterial production and highlights the necessity of considering these interactions-rather than searching for a singular mechanism-when evaluating the causes of ongoing changes in low-nutrient lakes.},
	keywords = {agriculture, basin morphometry, Cyanobacteria, eutrophication, Gloeotrichia, ice-out, land use, Maine, New Hampshire, paleoecology, Sediment chemistry, watershed},
	issn = {2150-8925},
	doi = {10.1002/ecs2.v11.610.1002/ecs2.3170},
	url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.3170},
	author = {Ewing, Holly A. and Weathers, Kathleen C. and Cottingham, Kathryn L. and Leavitt, Peter R. and Greer, Meredith L. and Carey, Cayelan C. and Steele, Bethel G. and Fiorillo, Alyeska U. and Sowles, John P.}
}
@conference {1278,
	title = {The Effect of Different Acid Treatments on the Radiocarbon Age of Sedimentary Organic Matter},
	booktitle = {EOS, Transactions, American Geophysical Union},
	year = {2001},
	note = {Date revised - 2007-02-01SuppNotes - Session: OS41A 9 The Truth About Paleoceanographic Proxies - What Are They Really Telling Us III Posters.Last updated - 2016-05-27},
	month = {January 2001},
	publisher = {American Geophysical Union, 2000 Florida Ave., N.W. Washington DC 20009 USA, [mailto:service@agu.org]},
	organization = {American Geophysical Union, 2000 Florida Ave., N.W. Washington DC 20009 USA, [mailto:service@agu.org]},
	abstract = {To date the bulk organic carbon in marine sediments it is necessary to first remove any inorganic carbon present by acidification. We tested three different acid treatments to see how the different methods affected the stable and radio-carbon isotopic values of the remaining organic matter. The standard NOSAMS method is to react the sediment with repeated aliquots of1.2N HCl until no visible dissolution reaction is present. The remaining sediment is then rinsed with distilled water. This method leaves a carbonate-free sediment that is easy to combust but suffers from the possible removal of acid-soluble organic matter. We compared this method to two methods that do not require rinsing of the sediments after acid treatment--a vapor phase acidification method using concentrated HCl (Hedges and Stern, 1984) and an in situ acidification with sulfurous acid (Verardo et al., 1990). Scaling these methods up to deal with the amount of sediment required for a radiocarbon date can present challenges that are not evident when dealing with the small quantities required for a percent organic carbon measurement. Vapor phase acidification of high carbonate sediments leaves hygroscopic salts that can impede sample combustion. Sulfurous acid is a weak acid and it is very difficult to determine when all the carbonate has been removed from a sediment sample. We tested sediments from 6 locations in (or near) the Atlantic Ocean that represented riverine, estuarine, and marine environments as well as a range of both organic and inorganic concentrations. We will present the isotopic results for these sediments and evaluate what is the most appropriate method to use. Hedges J.I. and J.H. Stern (1984) Limnol. Oceanogr. 29, 657-663. Verardo D.J., P.N. Froelich and A. McIntyre (1990) Deep-Sea Res. 37, 157-165.},
	keywords = {A, Atlantic, Acidification, Brackish, Brackishwater environment, carbon cycling, Chronostratigraphy, Estuarine sedimentation, organic carbon, organic matter, Palaeoceanography, Radioactivity and radioisotopes, Radiocarbon dating, Sediment chemistry, Stable isotopes},
	url = {https://search.proquest.com/docview/19468089?accountid=29119},
	author = {Batista, F and McNichol, A P and Gerlach, D S}
}
