Jeke, N., & Zvomuya, F.. 2018.
In situ phytoremediation of municipal biosolids is a promising alternative to land spreading and landfilling during decommissioning of end-of-life municipal lagoons. Plant root simulator (PRS) probes can be used to examine nutrient availability during phytoremediation, but their use under wetland conditions is limited. This study examined nutrient availability using PRS probes during phytoremediation of biosolids vegetated with cattail. The probes were buried in the sediment for seven sequential 2-wk burial periods beginning in June 2014. Plants were harvested to determine biomass yield and nutrient content. Nitrogen supply rate did not change significantly with sampling period in June and July (4.5 to 5.9 μ g cm-2 [2 wk]-1) but increased thereafter to 11.8 μg cm-2 [2 wk]-1). Phosphate supply rate (20.5 to 24.2 μ g cm-2 [2 wk]-1 did not differ significantly among sampling times. Cumulative supply rates of the macronutrients N, P, K, Ca and Mg (r = 0.77- 0.92) and the micronutrients B, Fe, and Mn (r = 0.7- 0.81) were highly correlated with cattail uptake, while the correlation was weaker for Cu (r = 0.42) and Zn (r = 0.40). Maximum attainable biomass yield (0.87 kg m-2) coincided with the period of maximum nutrient uptake, indicating that harvesting cattail between late August and early September maximizes nutrient removal. In situ burial of PRS probes appears to be an effective method of measuring availability of macronutrients but may have limited effectiveness for Cu and Zn.
