Nitrogen and Phosphorus Exchanges Across the Sediment–Water Interface in a Bay of Lake Chaohu

Abstract

A year-long field investigation was carried out in the most heavily polluted bay of Lake Chaohu to assess the temporal exchanges of ammonium nitrogen (NH þ 4 -N) and soluble reactive phosphorus (SRP) across the sediment-water interface (SWI) and to provide remediation advises. Results showed that the monthly average fluxes of NH þ 4 -N and SRP were 31.38 and 6.98 mg m -2 d -1 , respectively, both of which were higher than those in many other hyper-eutrophic lakes around the world. The exchanges of NH þ 4 -N and SRP were both closed related to the oxygen penetration. Low oxygen penetration depth and generally negative oxygen uptake rates provoked the dissolution of redox sensitive phosphorus and labile NH þ 4 -N in the sediment and increased the fluxes. In addition, the generally higher fluxes during late spring to autumn should be noted during the reduction of internal loadings, when applicable techniques should be implemented accordingly to achieve better reduction effects. Water Environ. Res., 90, 1956Res., 90, (2018.

Efficient Disposal of the Aqueous Products of Wet Organic Waste Hydrothermal Carbonization by Paddy Constructed Wetlands

“…Component 3 was also found to correspond to marine humic-like components . Component 4 corresponds to terrestrially derived humic material . Due to the different dissolved organic matter concentrations of the dilute first and seventh surface water samples, the fluorescence intensities of components 1, 2, 3, and 4 identified by PARAFAC analysis should be normalized by the SUVA 254 , which indicates the practical fluorescent DOM compositions of the first and seventh surface water samples.…”

“…67 Component 4 corresponds to terrestrially derived humic material. 68 Due to the different dissolved organic matter concentrations of the dilute first and seventh surface water samples, the fluorescence intensities of components 1, 2, 3, and 4 identified by PARAFAC analysis should be normalized by the SUVA 254 , which indicates the practical fluorescent DOM compositions of the first and seventh surface water samples. Figure 5b,c presents the corresponding fluorescence intensities of components 1, 2, 3, and 4 for the first and seventh surface water samples; it was observed that after treating the paddy constructed wetlands, the seventh-day surface water sample exhibited lower fluorescence intensities (5.7−88.2%) than the samples from the first day.…”