期刊
WATER RESEARCH
卷 47, 期 3, 页码 1491-1502出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2012.12.014
关键词
Lake aeration; Iron; Manganese; Phosphorus release; Redox potential; Sedimentation
资金
- KLIMZUG 'INKA BB' project of the German Federal Ministry of Education and Research (BMBF)
Iron salts have been regarded as unsuitable precipitants for sustainable sedimentary P retention, because Fe-bound P is released at low redox potential. The longevity of an Fe3+ application (500 g m(-2)) in 1992 was studied in a dimictic lake. Release of Fe and P as well as their co-precipitation were observed dependent on artificial aeration in 2010 and only natural oxygenation in 2011. Sediment core stratigraphy by mu X-ray fluorescence analysis revealed that Fe is relocating towards the surface, representing a dynamic P trap with a molar Fe:P ratio of 7. Even at this favourable ratio, P release cannot be suppressed. Settling fluxes of Fe, Mn and P, determined by a multi trap at two day resolution, during aeration and oxygenation, showed that released P can be efficiently precipitated independent of the nature of the oxygen supply. Thus, P release is not relevant for the P supply to the epilimnion, since at overtum most P is co-precipitated by the concurrently hypolimnetically accumulated Fe. To increase the availability of reactive (dithionite extractable) Fe for P binding, our Fe dosage calculation considers Fe in surplus. Beside external and internal P sources to be precipitated in a stoichiometric Fe:P ratio of 5, additional Fe equivalents of 25% for sedimentary organic carbon and to bind soluble sulfides are required. A long-term effect can be achieved only if the external P loading is sufficiently reduced, and Fe is added to >= 200 g m(-2). (C) 2012 Elsevier Ltd. All rights reserved.
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