Phosphorus Fluxes at the Sediment-Water Interface in a Temperate Region Agricultural Catchment

Abstract

Phosphorus (P) release and flux at sedimentwater interface was hypothesized to vary with studied catchment branches due to differences in water chemistry of recharging groundwater. Stream water, seepage water, groundwater, and resurgence groundwater were collected, and their dissolved reactive P (DRP) concentrations and related water chemistry variables (pH, dissolved oxygen, cations, and anions) were measured to identify P sources in seepage water and resurgence groundwater and to look into their impacts on stream water DRP. Results showed that the groundwatercarried P concentrations were negligible, and, thus, not a direct source of DRP to stream water. However, the upwelling groundwater could contribute to stream water DRP by dissolving calcite-bound P in top sediments of branch 15. The seepage experiment indicated that in branch14, sediment release of reducible P was minimal. Furthermore, the presence of impermeable clay layer over the streambed of branch 14 prevented the transport of water and nutrients from beneath sediments to stream water, further reducing the P flux across the sedimentwater interface. This study revealed that in branch 14, the recharge of anoxic groundwater did not significantly influence stream water P, due directly to its low P concentration, or indirectly to the lack of reducible P and the poor hydrological connectivity in bottom

Distribution Characteristics of Phosphorus in the Sediments and Overlying Water of Poyang Lake

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“…Lake sediment could serve as a carbon and nutrient sink for materials entering the aquatic ecosystem (Bouwman et al, 2013). Thus, sediment contains high concentrations of nutrients and biomass; furthermore, its biochemical processes have a major influence on the nutrient balance of the overlying water (Heinen and McManus, 2004; Su et al, 2014). Likewise, the primary production and nutrient concentration of an overlying waterbody also affect the sediment bacterial community (Wobus et.…”

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“…Noticeably, once the sedimentary contaminants are released into water, the aquatic eco-balance is inevitably disrupted. However, conventional river improvement projects usually only pay attention to the overlying water and surrounding greenery, but ignore the remediation of polluted sediment [6][7][8]. The contaminated sediment, without proper management, becomes a continuous source of endogenous pollution for the river.…”