Simple and effective remediation strategies of Martian perchlorates

May combine two claims.

In Martian simulants, perchlorate caused uniform reduction in plant growth and prevented germination compared to no perchlorate, and promoted elevated metal and phosphorus release.

“For instance, the presence of perchlorate in Martian simulants led to uniform reduction in plant growth and prevention of plant germination compared to no perchlorate treatments, along with promoting elevated metal and phosphorus release from the simulants (Oze et al., 2021).”

• cites Oze et al., 2021 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Biological perchlorate reduction occurs primarily in anaerobic environments.

“Additionally, biological perchlorate reduction occurs primarily in anerobic environments (Carlström et al., 2015).”

• cites Carlström et al., 2015 sourceCould not verify

  The Introduction describes bacteria that use perchlorate as an electron acceptor, and the Discussion describes anaerobic pathways of aromatic degradation during (per)chlorate reduction. Neither passage establishes that biological perchlorate reduction occurs primarily in anaerobic environments. Searches for anaerobic environments and anoxic perchlorate respiration found no statement about where reduction predominantly occurs. (LLM, conf=0.73)

  Experimental — accuracy not yet measured

May combine two claims.

Sulfate minerals, such as jarosite and ferric sulfates, will break down at 500-600°C, leading to evolution of SO2 and O2, inducing oxidation of organic matter and subsequent evolution of CO2.

“For instance, sulfate minerals, such as jarosite and ferric sulfates, will break down at 500-600˚C, both of which lead to the evolution of SO 2 and O 2 , inducing the oxidation of organic matter and subsequent evolution of CO 2 (Lewis et al., 2015).”

• cites Lewis et al., 2015 sourcePartly supported

  Results §3.6 reports that both samples began producing SO₂ around 500–600°C and that oxygen from jarosite decomposition could oxidize organic carbon to CO₂. But oxygen was not detected from the natural jarosite clay; it was detectable from ferric sulfate hydrate only at 600°C and above. The claim overstates the evidence by saying both minerals evolved detectable O₂ at 500–600°C and induced organic-matter oxidation. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

The lack of effect of additional electron acceptors may be due to metabolic versatility and differing mechanisms of perchlorate metabolism among species, resulting in inconsistent results.

“However, this may be due to the metabolic versatility and differing mechanisms of perchlorate metabolism among species, resulting in inconsistent results (Youngblut et al., 2016).”

• cites Youngblut et al., 2016 sourcePartly supported

  The Comparative Steady-state Kinetics section (page not provided) reports that PcrAB turns over several oxyanions and behaves differently from E. coli nitrate reductase, supporting a limited point about biochemical differences. It does not examine whether additional electron acceptors have no effect or attribute inconsistent results among species to metabolic versatility or differing perchlorate-metabolism mechanisms. (LLM, conf=0.72)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

In Oze et al. (2021), complete loss of perchlorate with leaching from Martian simulant was not obtained, and the concentration of remaining perchlorate was not stated.

“In their study, complete loss of perchlorate with leaching from Martian simulant was not obtained; however, the concentration of remaining perchlorate was not stated (Oze et al., 2021).”

• cites Oze et al., 2021 sourceSupported

May combine two claims.

Directed evolution native soil microbiome improved perchlorate reduction over time but stopped before fully removing all perchlorate.

“A native soil microbiome from Earth was sourced to break down perchlorates, and its activity improved over time through directed evolution, though it stopped before fully removing all perchlorate.”

May combine two claims.

Microbial perchlorate reduction was feasible but did not demonstrate acceptable repeatability in evolved soil communities or pure microbial cultures.

“Microbial reduction was feasible, but it did not demonstrate acceptable repeatability in evolved soil communities or pure microbial cultures”

May combine two claims.

General trends in perchlorate reduction performance were observed across species with A. brasilense reducing perchlorate concentrations the most and A. hansenii being the least effective strain.

“General trends in perchlorate reduction performance were observed across species with A. brasilense reducing perchlorate concentrations the most and A. hansenii being the least effective strain.”

May combine two claims.

During distillation, a yellow color was apparent in the concentrated distillate, indicating the presence of many ions that had been leached from the soil.

“During distillation, a yellow color was apparent in the concentrated distillate, indicating the presence of many ions that had been leached from the soil.”

May combine two claims.

At 1:5 solid:liquid, the first leach left 5% perchlorate remaining, and subsequent leaches had no perchlorate detected.

“However, the 1:5 volume of water leached nearly all perchlorate after the first leach with 5% remaining, and in subsequent leaches, there was no perchlorate detected (Figure 2).”

May combine two claims.

Microbial cultures tested for the biodegradation of perchlorate proved capable of being sourced and selected from terrestrial soils and compete with pure cultures known to reduce perchlorate.

“Microbial cultures tested for the biodegradation of perchlorate proved to be capable of being sourced and selected from terrestrial soils and compete with pure cultures known to reduce perchlorate;”

May combine two claims.

Some perchlorate degradation occurred below 250°C, with full degradation between 426 and 470°C.

“Some degradation occurred below 250˚C with full degradation between 426 and 470˚C (Figure 1).”

May combine two claims.

Overall, biological perchlorate reduction occurs quickly, within 4 days, has little activity thereafter, and is marked with high variability.

“Overall, it appears that biological perchlorate reduction occurs quickly, within 4 days, has little activity thereafter, and is marked with high variability.”

Probably not a substantial claim: may not pass S3 (load-bearing).

After distilling the leachate, the water volume was 84 mL.

“The volume of water after distilling the dissolved perchlorate leachate was 84 mL.”

Probably not a substantial claim: may not pass S3 (load-bearing).

For the 1:5 leach, 94 mL of the initial 100 mL water used for leaching was recovered.

“For the 1:5 leach, 94 mL out of the initial 100 mL water used for leaching was recovered.”

May combine two claims.

65%-75%, 45%-70%, and 25%-40% of perchlorate was removed from the 10, 5, and 1 g/kg treatments, respectively.

“For instance, 65%-75%, 45%-70%, and 25%-40% of perchlorate was removed from the 10, 5, and 1 g/kg treatments, respectively.”

May combine two claims.

Distilled leachate contained no detectable perchlorate and had an EC of 52 μS cm-1, similar to the DI water source (32 μS cm-1).

“Once the leachate was distilled, it contained no detectible perchlorate and had an EC of 52 μS cm -1 , which was similar to the DI water source (32 μS cm -1 ).”

May combine two claims.

In the additional directed evolution experiment, the third generation performed best and no degradation occurred in the fourth and fifth generations.

“An additional directed evolution experiment was conducted using fresh field soils to evaluate the viability of fourth and fifth generations but resulted in similar results with the third generation performing best and no degradation occurring in the fourth and fifth generations (data not shown).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The thermal degradation experiment was repeated and results were averaged.

“The entire experiment was repeated, and the results from the two experiments were averaged.”

Probably not a substantial claim: may not pass S3 (load-bearing).

All measured variables had three experimental replicates.

“There were three experimental replicates for all measured variables.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Maintaining positive pressure in incubation chambers ensures leakage directs air outward, preventing atmospheric contamination of samples.

“Maintaining positive pressure in the chambers ensures that any leakage directs air outward, preventing atmospheric contamination of the samples.”

May combine two claims.

Perchlorate has high solubility and does not sorb well to soil minerals or organic matter, making it potentially mobile with flowing water.

“Perchlorate has a high solubility and does not sorb well to soil minerals or organic matter (Fang & Naidu, 2023), making perchlorate potentially mobile with flowing water.”

• cites Fang & Naidu, 2023 sourceNot checked — no full text of the source

May combine two claims.

Thermal decomposition and leaching with distillation are low-technology, highly effective options to remediate perchlorate from Martian surface minerals, though their energy inputs and alteration of soils may be undesirable in certain circumstances.

“Overall, the thermal decomposition and leaching with distillation approaches were considered low technology, highly effective options to remediate perchlorate from Martian surface minerals, although their energy inputs and alteration of soils may be undesirable in certain circumstances.”

• Also stated in: § Abstract · hedged

  “Overall, thermal treatment and leaching with distillation appear to be simple and reliable strategies for perchlorate cleanup, though they require energy and may influence soil properties.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The leaching experiment was repeated and results were averages of two experiments.

“The entire experiment was repeated, and the results are averages of the two experiments.”

May combine two claims.

Perchlorate acts as a chaotrope that reduces protein stability, making oxidized Cl species on Mars major obstacles to human, plant, and microbial use of regolith for ISRU.

“Regardless of formation processes, the widely distributed oxidized Cl -species on Mars will pose major obstacles to human, plant, and microbial use of regolith for ISRU due to its toxicity, since perchlorate acts as a chaotrope that reduces the stability of proteins (J.J. J. Clark, 2000).”

• cites J.J. J. Clark, 2000 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Perchlorate species on the Martian surface are modeled to exist as Mg(ClO4)2·6H2O, KClO4, and NaClO4·2H2O, and if chlorate is included, NaClO3 and Mg(ClO3)·6H2O.

“Perchlorate species have been modeled from the WCL data to exist on the Martian surface as Mg(ClO 4 ) 2 •6H 2 O, KClO 4 , and NaClO4•2H 2 O, and if chlorate (ClO 3 -) is included, NaClO 3 and Mg(ClO 3 )•6H 2 O (Toner et al., 2014).”

• cites Toner et al., 2014 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). The quote only partly states this claim.

There were five experimental replicates for each treatment in the incubation experiments.

“There were five experimental replicates for each treatment.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Due to refrigerator malfunction during the resilience experiment and inability to order new strains, several strains were not tested in the time-series experiment.

“Unfortunately, due to refrigerator malfunction during the resilience experiment, and inability to order new strains from NRRL, several of the strains were not tested in the subsequent time-series experiment.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Other highly soluble ions would also leach, which may benefit subsequent biotic activity by reducing the salinity of the surface regolith materials.

“Other highly soluble ions would also leach, which may benefit subsequent biotic activity by reducing the salinity of the surface regolith materials.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The authors are not aware of studies that investigate perchlorate decomposition directly in substrate as a soil remediation strategy.

“Although the thermal decomposition of perchlorates has been widely studied in propellants (Vyazovkin & Wight, 1999), we are not aware of studies that investigate perchlorate decomposition directly in substrate as a soil remediation strategy.”

• cites Vyazovkin & Wight, 1999 sourceNot checked — no full text of the source

May combine two claims.

Thermal degradation at temperatures above 500°C will most likely alter the composition of surface minerals specifically by reducing the abundance of nitrates and sulfates but also altering any phyllosilicates present in the soil.

“thermal degradation at temperatures above 500˚C will most likely alter the composition of surface minerals specifically by reducing the abundance of nitrates and sulfates but also altering any phyllosilicates present in the soil.”

• AssumptionRests on an assumption: Nitrates evolve below the perchlorate evolution temperature.
• AssumptionRests on an assumption: Phyllosilicate clay minerals release interlayer water below 200°C and dehydroxylate at 500-700°C.

Classified as probably not a substantial claim.

The ratios used in this study were lower than those used in other literature.

“although ratios used in this study were lower than those used in other literature (Stein et al., 2022;Zhu et al., 2016).”

• cites Stein et al., 2022Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Zhu et al., 2016 sourceNot checked — no full text of the source

Classified as probably not a substantial claim.

In order to grow plants in Martian soils, the salinity of the surface minerals will need to be reduced.

“Regardless, in order to grow plants in Martian soils, the salinity of the surface minerals will need to be reduced, as leaching is a common practice on Earth to remediate saline soils.”

• AssumptionRests on an assumption: Leaching is a common practice on Earth to remediate saline soils.

Probably not a substantial claim: may not pass S3 (load-bearing).

A limitation of the current study is that the additions of perchlorate to the simulant material may not fully represent what occurs on Mars.

“It is important to note that a limitation of the current study is that the additions of perchlorate to the simulant material may not fully represent what occurs on Mars.”

May combine two claims.

Leaching would remove other soluble ions in the soil, such as nitrates, which may reduce the availability of plant available nutrients.

“Therefore, leaching would remove other soluble ions in the soil, such as nitrates, which may reduce the availability of plant available nutrients.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Perchlorate remediation in Martian soils will be necessary for use as a growth medium for plants, which ultimately supply food/fiber production, water purification through transpiration, and O2 generation.

“Perchlorate remediation in Martian soils will be necessary for use as a growth medium for plants, which ultimately supply food/fiber production, water purification through transpiration, and O 2 generation.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

If distillation is chosen, energy inputs will be required.

“If distillation is chosen, energy inputs will be required.”

May combine two claims.

Thermal degradation requires energy inputs and, while likely not altering minerals, will evolve metal nitrates at reported temperatures.

“Thermal degradation will further require energy inputs, and the introduction of heat, while likely not altering minerals, will also evolve metal nitrates at the reported temperatures (Mu & Perlmutter, 1982).”

• cites Mu & Perlmutter, 1982 sourceNot checked — no full text of the source

May combine two claims.

All microbial experiments were conducted with sterile controls, and no control samples exhibited perchlorate reduction.

“All microbial experiments were conducted with sterile controls, and no control samples exhibited perchlorate reduction.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Leaching would have less velocity and greater residence in the soil column due to reduced gravity on Mars.

“Leaching would have less velocity and greater residence in the soil column due to reduced gravity on Mars.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Because the ISE detection limit was 0.7 mg L-1, trace amounts of perchlorate could have remained after leaching.

“Because the detection limit of the ISE was 0.7 mg L -1 , it is possible that trace amounts could have remained after leaching.”

May combine two claims.

Using microbial degradation requires introduction of terrestrial microorganisms to Martian regolith, which will be necessary if plants are grown in Martian soils.

“albeit requiring the introduction of terrestrial microorganisms to Martian regolith, which may not be desirable but will be necessary if plants are grown in Martian soils.”

May combine two claims.

The failure of the fourth and fifth microbial bottleneck indicates either the cultures had lost their perchlorate reduction potential, experienced an extinction event, or became non-resilient to the environment.

“The failure of the fourth and fifth microbial bottleneck indicates either the cultures had lost their perchlorate reduction potential, experienced an extinction event, or became non-resilient to the environment.”