The Mineral Trap Sampler (Min-Trap®, U.S. Patent No. 11,002,643) technology is a cost-effective in situ monitoring tool for passively collecting direct mineralogical data to manage in situ remediation approaches that rely on the formation, dissolution and/or transformation of solid-phase minerals to sequester or degrade contaminants.
MIN-TRAP® SAMPLER ADVANTAGES:
DIRECT
Post-deployment analyses provide direct feedback on the in situ formation, characteristics, and activity of target minerals.
NO DRILLING
Min-Traps® eliminate the costs, time, data quality, and health and safety risks associated with drilling for samples.
LONG-TERM
Min-Traps® provide a technical basis to support estimates of long-term mineral stability and/or reactivity and implications for transition from active to passive treatment. In addition, Min-Traps® can confirm ongoing effectiveness of active in-situ remediation, passive treatment, and long-term monitoring programs.
BROAD APPLICABILITY
Min-Traps® are applicable to combined biotic/abiotic degradation of chlorinated solvents as well as in situ oxidation, in situ chemical reduction, or pH neutralization of metals.
HOW TO USE MIN-TRAP® SAMPLERS:
The Min-Trap® sampler is applicable to a wide variety of contaminants and treatment approaches.
Use Min-Trap® samplers to help answer…
- Are reactive iron minerals formed for combined biotic/abiotic degradation of chlorinated solvents?
- Will metals like arsenic co-precipitate or adsorb to iron oxides during in situ chemical oxidation?
- Are metal sulfides formed during in situ chemical reduction at Cr(VI) sites?
- Will pH neutralization increase solid phase minerals?
RESOURCES
This 2023 paper reviews passively monitoring In-Situ iron sulfide mineral formation for chlorinated solvent treatment.
This 2023 paper provides guidance and examples for using the Min-Trap sampler.
Read the final ESTCP report for the creating and validation of the Min-Trap sampler
This 2021 paper highlights the power of the Min-Trap for monitoring in situ formation of iron sulfide minerals
This 2019 paper reviews analytical methods related to mineral-mediated abiotic contaminate transformation.
ANALYSES
Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS)
SEM is a powerful technique that can visually identify target minerals in the Min-Trap® sample and generate valuable information about particle sizes, shapes, and surface area. EDS is used to determine the elemental composition at multiple locations within the sample. The elemental ratio is used to identify the minerals present in the sample.
Aqueous and Mineralogical Intrinsic Bioremediation Assessment (AMIBA)
AMIBA is a collection of analyses performed to quantify iron and sulfur availability in various redox states to allow assessment of the microbial/mineral/contaminant interactions. AMIBA includes acid volatile sulfide, chromium extractable sulfides, strong acid soluble ferrous and ferric iron, and weak acid soluble ferrous and ferric iron.
CENSUS® qPCR
Acetylene, an intermediate of abiotic degradation of chlorinated compounds, is readily biodegraded and may not appreciably accumulate in groundwater. As an alternative indicator, CENSUS® qPCR quantification of acetylene hydratase genes (AHY) encoding the enzyme that mediates anaerobic acetylene biodegradation may suggest acetylene production even if dissolved acetylene has not been detected. CENSUS qPCR® assays for sulfate-reducing bacteria (APS) and methanogens (MGN) can also be used as a line of evidence to demonstrate a sulfate-reducing biogeochemical regime.
Magnetic Susceptibility
Magnetic susceptibility provides an inexpensive estimate of the quantity of magnetite, a mixed valence iron mineral. Magnetite (Fe3O4 ) is a naturally occurring iron mineral believed to mediate abiotic degradation of PCE, TCE, cis-DCE, vinyl chloride, and carbon tetrachloride.
X-Ray Diffraction (XRD)
XRD can provide relative abundances of reactive minerals including pyrite and mackinawite, reactive iron-bearing minerals that will transform a variety of chlorinated compounds.