Sulphate reduction determines the long-term effect of iron amendments on phosphorus retention in lake sediments

Abstract

Purpose This field study aimed to guide the planning of iron amendments for phosphorus retention by investigating the long-term fate of iron added to two urban lakes (Plötzensee and Groß Glienicker See) in Berlin, Germany. The contributions of iron dosing to improve lake status as well as the relevance of competing processes for management success were evaluated. Methods Sediment stratigraphy, as well as occurrence of iron minerals, and fluxes between water and sediment were examined using geochemical analyses (i.e. element composition, sequential extraction, X-ray diffraction, and pore water analyses). A one-box lake model was used to relate these fluxes to monitoring data from the water column and to sediment inventories. Results In both lakes, the added iron was preserved in the sediment. Whereas phosphorus retention increased following the addition of iron to Groß Glienicker See, sulphur was retained by the excess iron in Plötzensee. This contrasting effect is attributed to significantly different sulphate reduction rates in two lakes (Wilcoxon rank sum test: W = 25, p = 0.008). According to the one-box model, sulphate reduction explained both the decrease in measured sulphate concentrations after iron application as well as the observed increase in sulphur deposition in the sediments. Conclusion Management interventions involving iron amendments to enhance phosphorus retention must consider the competing process of iron sulphide formation during the entire management plan period, and additional iron may need to be applied to account for this effect.

Iron-Added Sediment Microbial Fuel Cells to Suppress Phosphorus Release from Sediment in an Agricultural Drainage

“…2 b, c). Although adding Feincorporated materials aided P fixation in sediment, it was not successful if sulfur and organic matter contents in sediment were high [51,52]. The total S content in our sediment was similar to that of surface sediment of Ena Bay, Japan [53].…”

The Forms of Phosphorus in Sediments of Large Lakes (Poyang Lake) and Its Impact on Endogenous Release

“…(b) Schematic diagram of P cycling in Poyang Lake based on structural equation modeling and lake P cycling theory. The following abbreviations are utilized: POP: particulate organic P, PIP: particulate inorganic P, DIP: dissolved inorganic P, DOP: dissolved organic P, AAP: algal available P (refer to Reddy and Delaune, Yuan, Heinrich, Li). ①-④: Conceptual model illustrating the relationships between the Fe III –Fe II redox wheel and P cycling in anaerobic soil/sediment (refer to Text S5 and Li for details).…”

Sustainable lake restoration: From challenges to solutions

“…Each of these methods has its own specifics that must be considered. For example, management interventions involving iron amendments must consider the competing process of iron sulphide formation (Heinrich et al, 2022) and the potential of renewed P release under anoxia during the entire management period.…”