Clearing the muddy waters: using lake sediment records to inform agricultural management

Autor: Adam Carson, Eleanor Jennings, Suzanne Linnane, Siobhan N. Jordan
Rok vydání: 2014
Předmět:
Zdroj: Journal of Paleolimnology. 53:1-15
ISSN: 1573-0417
0921-2728
DOI: 10.1007/s10933-014-9803-5
Popis: Milltown Lake is located in the Irish drumlin belt where small lakes are interspersed amongst rolling hills. Because of poor drainage characteristics of soils in this region, grassland agriculture dominates, with beef rearing and dairying as the main agricultural enterprises. We used paleolimnological techniques in conjunction with export coefficients to investigate the relationship between historical development of eutrophication in the lake and changes in nutrient loading from the watershed. Sediment cores representing the period ~1970 to 2008 were analysed for fossil pigments using high performance liquid chromatography to provide proxies for changes in abundance of the main algal groups. Geochemical variables, including total phosphorus, were also analysed, and nutrient loading was estimated using historical data. Concentrations of all major pigments increased up-core, as did nutrient loading from the watershed, between ~1970 and 2008. Export coefficient estimates showed that, on average, 82.2 % of P loads were attributable to two sources, cattle and grassland. More specifically, the P load from cattle was strongly correlated to overall algal abundance, whereas the P load from people was negatively related to algal abundance indicators. Results also suggested that artificial fertilisers were less important drivers of algal abundance than organic manure from cattle. These results highlight the potential problems associated with farming practices that generate large amounts of organic manure, especially when located on poorly drained and steeply sloping lands. The findings contribute to the management of such small lakes, particularly given the potential conflict between increasing agricultural output and the implementation of the European Union Water Framework Directive on a national scale.
Databáze: OpenAIRE
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