# Importance of Capping Material Properties in Remediation of Mine Tailings

> **NIH NIH P42** · UNIVERSITY OF ARIZONA · 2022 · $296,331

## Abstract

ABSTRACT (Project 5: Maier, Neilson, Babst-Kostecka, Rasmussen)
Soil contamination with trace elements in the vicinity of mining sites and smelters poses a serious threat to
humans and the environment around the globe. Revegetation of mine tailings to minimize the dispersal of
pollutants via wind or ground water (i.e. phytoremediation) is a promising “green” and low-cost intervention
to toxic exposures. Unfortunately, plant growth is inhibited on most tailings, making it necessary to provide
additional healthy substrate for seed germination and seedling growth. The current practice is the installation
of an uncontaminated soil-gravel-rock cap over the tailings prior to plant seeding, with stockpiles of such
material being readily available, a technology known as “cap and plant”. However, critical knowledge gaps
regarding plant-soil interactions have prevented a broad and efficient implementation of this technology. The
primary objective of this project is to identify the optimal strategy for generating a lasting vegetation cover at
hazardous mining sites. The guiding hypothesis is that the biophysicochemical properties of capping material
are critical for the development of robust root systems that can propagate into the underlying contaminated
mine tailings. Using an innovative experimental design, this project will develop specific soil health indices
and assess the effects of capping material depth and quality on root system architecture in a prospective
plant species known as saltbush (Atriplex lentiformis) for phytoremediation. Various capping materials from
stockpiled overburden and adjacent natural deposits will be tested in three consecutive greenhouse studies
that bring together advanced ecological, genomic, and soil health assessments. Specifically, root system
development will be monitored using a noninvasive phenotyping method based on rhizotrons, filled with
different combinations of capping material and mine tailings from Superfund sites across the US Southwest.
Once the optimal soil and plant parameters are identified, possibilities to amend existing but low-quality
capping material in a cost-effective way will be explored. This project will yield an unprecedented mechanistic
understanding of concurrent changes in plant root system architecture and function in response to the quality
and depth of capping materials used for mine tailing restoration. Capitalizing on this knowledge, specific
guidelines towards the remediation of hazardous sites will be developed and directly transferred to the mining
industry and regulators. As such, the project outcome will be valuable for the economy and society. In
addition, our findings will serve as a global template for mitigating human and environmental health issues in
areas affected by mines and smelters.

## Key facts

- **NIH application ID:** 10337265
- **Project number:** 5P42ES004940-33
- **Recipient organization:** UNIVERSITY OF ARIZONA
- **Principal Investigator:** Raina M Maier
- **Activity code:** P42 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $296,331
- **Award type:** 5
- **Project period:** 1997-04-01 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10337265

## Citation

> US National Institutes of Health, RePORTER application 10337265, Importance of Capping Material Properties in Remediation of Mine Tailings (5P42ES004940-33). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10337265. Licensed CC0.

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