Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 628-629, Issue -, Pages 990-996Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2018.02.059
Keywords
Lake restoration; P sorbcm; Iron oxyhydroxide; Iron reduction; Internal P loading
Categories
Funding
- Junta de Andalucia (Spain) [P10-RNM-6630]
- MINECO CTM (Spain) [2013-46951-R]
- European Regional Development Fund (ERDF)
- Danish Centre for Lake Restoration (a Villum Centre of Excellence)
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Metal hydroxides formed from aluminum (Al) and iron (Fe) salts can be used as phosphorus (P) adsorbents in lake restoration, but the application entails problems in low-alkaline lakes due to acid producing hydrolysis and potential formation of toxic metal ions. Therefore, we tested the potential of applying CFH-12 (R) (Kemira) - a dried, amorphous Fe-oxide with no pH effect - in lake restoration. Since Fe3+ may become reduced in lake sediments and release both Fe2+ and any associated P we also evaluated the redox sensitivity of CFH-12 (R) in comparison with freshly formed Fe(OH)(3). CFH-12 (R) was added to undisturbed sediment cores from three Danish lakes relative to the size of their mobile P pool (molar Fe:P-mobile dose ratio of similar to 10:1), and P and Fe fluxes across the sediment-water interface were compared with those from untreated cores and cores treated with freshly formed Fe(OH)(3). Under anoxic conditions, we found that CFH-12 (R) significantly reduced the P efflux from the sediments (by 43% in Lake Sonderby, 70% in Lake Hampen and 60% in Lake Hostrup) while the Fe2+ efflux remained unchanged relative to the untreated cores. Cores treated with freshly formed Fe(OH)(3) retained more P, but released significantly more Fe2+, indicating continued Fe3+ reduction. Finally, experiments with pure phases showed that CFH-12 (R) adsorbed less P than freshly formed Fe(OH)(3) in the short term, but was capable of adsorbing up to 70% of P adsorbed by Fe(OH)(3) over 3 months. With product costs only 30% higher than Al salts we find that CFH-12 (R) has potential for use in restoration of low-alkaline lakes. (C) 2018 Elsevier B.V. All rights reserved.
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