Phytoremediation of a Nitrogen‐Contaminated Desert Soil by Native Shrubs and Microbial Processes

Abstract

We combined phytoremediation and soil microbial nitrification and denitrification cycles to reduce nitrate and ammonium levels at a former uranium mill site near Monument Valley, Arizona. Ammonia used in uranium extraction was present throughout the soil profile. Sulfate, applied as sulfuric acid to solubilize uranium, was also present in the soil. These contaminants were leaching from a denuded area where a tailings pile had been removed and were migrating away from the site in groundwater. We planted the source area with two deep-rooted native shrubs, Atriplex cansescens and Sarcobatus vermiculatus, and irrigated transplants for 11 years at 20% the rate of potential evapotranspiration to stimulate growth, then discontinued irrigation for 4 years. Over 15 years, total nitrogen levels dropped 82%, from 347 to 64 mg kg À1 . Analysis of δ 15 N supported our hypothesis that coupled microbial nitrification and denitrification processes were responsible for the loss of N. Soil sulfate levels changed little; however, evapotranspiration reduced sulfate leaching into the aquifer. For arid sites where traditional pump-and-treat methods are problematic, the Monument Valley data suggest that alternatives that incorporate native plants and rely on vadose zone biogeochemistry and hydrology could be a sustainable remediation for nitrogen contaminated soil.

Remediation of a Riparian Site in the Brazilian Atlantic Forest Reached by Contaminated Tailings from the Collapsed Fundão Dam with Native Woody Species

“…Phytoremediation is an effective and ecofriendly strategy, which has been successfully employed to remediate mine tailings with high levels of alkalinity, salinity, and sites affected by N toxicity (Bell et al 1993; Qadir et al 2002; Abbas et al 2014; Glenn et al 2017; Kinidi and Salleh 2017). However, there are very few examples of field phytoremediation using woody species either for salt‐affected soils (Abbas et al 2014) or, specifically, for alkaline tailings, such as the red mud derived from the rupture of a dam in Hungary (Alshaal et al 2013).…”

Passive and active ecological restoration strategies for abandoned farmland leads to shifts in potential soil nitrogen loss by denitrification and soil denitrifying microbes

“…Abandoned farmland can sustain secondary succession (passive restoration) or afforestation (active restoration), leading to a mosaic of reconstructed vegetation and artificial forests (Nadal‐Romero et al, ). The passive and active restoration strategies could reshape the function of an ecosystem and its edaphic properties but also drive variations in soil microorganisms (Glenn, Jordan, & Waugh, ; Jiao et al, ; Lozano et al, ; Zhu, Wang, Chen, Li, & Wu, ). Denitrifying microorganisms are extensive in soil, accounting for approximately 0.5–5% of the total microorganisms (Levy‐Booth, Prescott, & Grayston, ).…”

Farmers' perceptions and adaptation behaviours concerning land degradation: A theoretical framework and a case‐study in the Qinghai–Tibetan Plateau of China

“…Moreover, to achieve sustainable remediation of contaminated agricultural land, it is imperative to prevent further contamination by using cleaner production approaches and to avoid irrigation with contaminated wastewater by farmers. It is also important to involve farmers in the decontamination process as they are the most familiar with land characteristics, especially when such remedies involve planting (Chi, Zuo, & Liu, ; Lin et al, ) and the use of biological waste (Batista, Gonzalez‐Fernandez, Abreu, Queralt, & Carvalho, ; Glenn, Jordan, & Waugh, ). In China, it is often the case that most contaminated agricultural sites are due to large‐scale practices, such as farmland irrigation with contaminated wastewater or surface runoff from mining sites, which can affect hundreds or thousands of hectares.…”