Effects of nitrate on phosphorus release: comparison of two Berlin lakes

Abstract

After installation of phosphorus elimination plants at the inflows of the eutrophic Lake Tegel and Schlachtensee, phosphorus (P) loading declined by a factor of 40 and 100, respectively. This resulted in a pronounced reduction of phosphorus concentrations in the lake water, followed by a decline of chlorophyll-a concentrations. However, for many years P release from sediments due to mineralization and desorption of sedimentary P continued. In Schlachtensee, the presence of nitrate above the sediment suppresses P release, because the Fe/P ratio is sufficient to provide enough aerobic sorption capacity. In Lake Tegel, some P release occurs even under aerobic conditions because of the low aerobic P sorption capacity of the sediments. There, nitrate could moderate the P release peaks which occur when the Fe-P cycle at the sediment water interface is disturbed by precipitation of iron sulfide after reduction of sulfate during times of high mineralization intensity. The potentially mobile P pool in the sediments of both lakes is rather small, indicating that the P release could subside after sufficient reduction of the external P load in Lake Tegel and the disruption of the internal P cycle in Schlachtensee.

Nitrogen transformations in a through‐flow wetland revealed using whole‐ecosystem pulsed 15N additions

“…Much of the photosynthesis was probably due to rooted macrophytes, which have an alternate source of N, namely the high NH z 4 concentrations in the porewaters. The epiphytes associated (Schauser et al 2006).…”

Effectiveness and Mode of Action of Calcium Nitrate and Phoslock® in Phosphorus Control in Contaminated Sediment, a Microcosm Study

“…(9) and (10)), resulting in a release of Fe 2+ due to the oxidation of metal sulfide to sulfate ). The mobilized Fe (II) diffused into the sediment-water interface, and when they contact with oxygen or nitrate, Fe (II) was oxidized (Schauser et al 2006). Nitrate can easily penetrate into the sediment, it was possible that most of Fe (II) was oxidized to Fe (III) by nitrate before they entered the water from sediment.…”

“…BD-P represents the redox-sensitive P forms, mainly bound to Fe and Mn compounds (Kozerski and Kleeberg 1998;Schauser et al 2006). BD-P showed a similar trend as NH 4 Cl-P.…”

Assessment of the acute toxicity of eutrophic sediments after the addition of calcium nitrate (Ibirité reservoir, Minas Gerais-SE Brazil): initial laboratory experiments

“…A decrease in the sediment redox potential reduces manganese (IV) to manganese (II) and iron (III) to iron (II) which in turn causes the release of phosphorus adsorbed on Fe and Mn oxide-hydroxide particles (Schauser et al, 2006), thus increasing phosphorus concentrations in the water column.…”

“…Another interesting point is the possible formation of nitrite and ammonium through the excessive addition of nitrate or lack of optimal conditions for its use as an electron acceptor. High inorganic nitrogen concentrations can cause toxicity to the aquatic life in the environment (Schauser et al, 2006).…”