Publication Date:
2017-09-15
Description:
Taihu Lake is hypereutrophic and experiences seasonal, cyanobacterial harmful algal blooms. These Microcystis blooms produce microcystin, a potent liver toxin, and are linked to anthropogenic nitrogen (N) and phosphorus (P) loads to lakes. Microcystis spp. cannot fix atmospheric N and must compete with ammonia-oxidizing and other organisms for ammonium (NH4+). We measured NH4+ regeneration and potential uptake rates and total nitrification using stable isotope techniques. Nitrification studies included separate NH4+ and nitrite (NO2−) oxidation rates and abundance of the functional gene for NH4+ oxidation, amoA, for ammonia-oxidizing archaea (AOA) and bacteria (AOB). Potential NH4+ uptake rates ranged from 0.02–6.80 µmol L−1 hr−1 in the light and 0.05–3.33 µmol L−1 hr−1 in the dark, and NH4+ regeneration rates ranged from 0.03–2.37 µmol L−1 hr−1. Nitrification rates exceeded previously reported rates in most freshwater systems. Total nitrification often exceeded 200 nmol L−1 d−1 and exceeded 1000 nmol L−1 d−1 at one station near a river discharge. In Meiliang Bay and the open lake, average NO2− oxidation rates (248 ± 39.0 nmol L−1 d−1) exceeded NH4+ oxidation rates (22.0 ± 6.00 nmol L−1 d−1; p
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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