Influence of submerged macrophytes, temperature, and nutrient loading on the development of redox potential around the sediment–water interface in lakes

Abstract

Redox potential is a significant factor in aquatic systems to regulate the availability of nutrients and some metals. To assess the driving variables regulating redox potential, background parameters (dissolved oxygen, pH, temperature, chlorophyll-a, soluble reactive and total phosphorus content of water, coverage and height of submerged macrophytes) and redox potential profiles around the sediment-water interface (SWI) were measured in simulated shallow lake ecosystems. There were two nutrient regimes (enriched and non-enriched) and three temperature scenarios (unheated; ?3.5°C; ?5°C) installed in the experimental setups, which were constructed to study the effects of global climate change. Temperature did not have any detectable effect on redox potentials, and we presume that nutrient addition had only indirect positive effects through triggering phytoplankton dominance which causes macrophyte absence. When submerged macrophytes were present in high density (80-100% coverage), redox potentials at the SWI varied between 60-215 mV and the mean redox potential was 133 ± 34 mV (mean ± 1 SD). In contrast to this, when phytoplankton dominance was coupled to low macrophyte density (0-20% coverage), the range of redox potentials at the SWI was 160-290 mV and the mean redox potential was 218 ± 34 mV. The results revealed the primary importance of submersed macrophytes; macrophyte coverage determined alone the redox potential of the sediment-water interface by 81%. This study suggests that possible positive effects of macrophytes on redox potential can be suppressed by their negative effects in case of 80-100% coverage and total inhabitation of the water column.

Sorption and degradation of triclosan in sediments and its effect on microbes

“…Previous research found that the biodegradation of TCS occurred mainly under aerobic condition with estimated t 1/2 values that ranged from 18 to 58 days (Ying et al, 2007;Chen et al, 2011). Although the oxygen in the overlying water were replenished during the incubation, redox potential can decrease rapidly at the water-sediment interface due to the microbial respiration (Boros et al, 2011). As a result, much higher t 1/2 values were observed in the sediments than in soils (18-58 days) under aerobic condition (Ying et al, 2007;Wu et al, 2009).…”

Outcomes of submerged macrophyte restoration in a shallow impounded, eutrophic river

“…Although trapping of particulates and associated sedimentation can improve water clarity, in this study cyanobacterial colonies were trapped within macrophytes, possibly contributing to higher TN and turbidity. We also noted higher TP and lower DO in macrophyte plots during the final two months of this study, when high plant density resulting from shallow conditions may have reduced oxygenation by restricting mixing and benthic primary production, causing release of phosphorus (Mortimer, 1942;Boros et al, 2011).…”

Repeated Fish Removal to Restore Lakes: Case Study of Lake Væng, Denmark—Two Biomanipulations during 30 Years of Monitoring

“…A likely explanation for the peaks in high winter concentrations of TP and DIP in periods with high Cov could be phosphorus release from decomposing macrophytes and redox sensitive release of phosphorus accumulated in the sediment. A dense and senescent macrophyte biomass at the sediment surface can result in reduced redox conditions and a reduced P sorption capacity [41].…”