PeerJ Preprints: Environmental Contamination and Remediationhttps://peerj.com/preprints/index.atom?journal=peerj&subject=1430Environmental Contamination and Remediation articles published in PeerJ PreprintsIsolation and characterization of psychrotrophic proteolytic bacteria from landfill site under temperate climatic conditions of Kashmir Himalayahttps://peerj.com/preprints/273912019-12-212019-12-21Basharat HamidArshid JehangirZahoor Ahmad BabaMuneer Ahmad WaniImran Khan
The temperate climatic regions face the problem of waste accumulation due to lower environmental temperatures. However, these regions harbor cold active microbes viz. psychrotrophic proteolytic bacteria that play an important role in the degradation of protenaceous materials of the waste stream. Hence in the present study psychrotrophic proteolytic bacteria were isolated from waste samples collected from landfill site by using random sampling method under environmental temperature of 10oC. By using serial dilution and spread plate technique a total of 8 morphologically different psychrotrophic proteolytic bacteria were isolated on skim milk agar media at pH of 7.0 and temperature of 10°C after 48hours. Under in-vitro conditions all the isolates produced significant quantities of protease over the control and diameters of hydrolysis zones ranged between 2 to 18 mm at temperature range of 5 to 20oC and after 72 hours. The corresponding quantitative protease activities of the isolates was significant that ranged between 0.5 to 2.25 U/ml and the isolate PB2 was most efficient with highest protease activity of 2.25U/ml at 20oC. Based on 16SrRNA analysis the isolate was identified as Pseudomonas florescence with 96% similarity. It was concluded that the isolates can grow in wide ranges of temperature and could be used for enhanced decomposition of organic wastes during lower temperature conditions in cold regions. Further the isolates could have industrial applications due to the production of cold active proteases that would help economic benefits through energy conservation.
The temperate climatic regions face the problem of waste accumulation due to lower environmental temperatures. However, these regions harbor cold active microbes viz. psychrotrophic proteolytic bacteria that play an important role in the degradation of protenaceous materials of the waste stream. Hence in the present study psychrotrophic proteolytic bacteria were isolated from waste samples collected from landfill site by using random sampling method under environmental temperature of 10oC. By using serial dilution and spread plate technique a total of 8 morphologically different psychrotrophic proteolytic bacteria were isolated on skim milk agar media at pH of 7.0 and temperature of 10°C after 48hours. Under in-vitro conditions all the isolates produced significant quantities of protease over the control and diameters of hydrolysis zones ranged between 2 to 18 mm at temperature range of 5 to 20oC and after 72 hours. The corresponding quantitative protease activities of the isolates was significant that ranged between 0.5 to 2.25 U/ml and the isolate PB2 was most efficient with highest protease activity of 2.25U/ml at 20oC. Based on 16SrRNA analysis the isolate was identified as Pseudomonas florescence with 96% similarity. It was concluded that the isolates can grow in wide ranges of temperature and could be used for enhanced decomposition of organic wastes during lower temperature conditions in cold regions. Further the isolates could have industrial applications due to the production of cold active proteases that would help economic benefits through energy conservation.A simple method for the selective quantification of polyethylene, polypropylene, and polystyrene plastic debris in soil by pyrolysis-gas chromatography/mass spectrometryhttps://peerj.com/preprints/279892019-12-052019-12-05Zacharias SteinmetzAaron KintziKatherine MuñozGabriele E. Schaumann
The lack of adequate analytical methods for the quantification of plastic debris in soil challenges a better understanding of their occurrence and fate in the terrestrial environment. With this proof-of-principle study, we developed a simple and fast method for the selective quantification of the three most environmentally relevant polymers polyethylene (PE), polypropylene (PP), and polystyrene (PS) in soil using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In order to facilitate the preparation of calibration series and to better account for the heterogeneity of soil matrix, polymers were dissolved in 1,2,4-trichlorobenzene (TCB) at 120 °C. Thereby, liquid sample aliquots from up to 4 g of solid sample became amenable to pyrolysis without further preparation. To evaluate the performance of this approach, three reference soils with 1.73–5.16 % organic carbon (Corg) were spiked at 50 and 250 μg g−1 of each polymer and extracted with TCB. A prior cleanup step with methanol, flocculation with KAl(SO4)2, and Fenton digestion were tested for their suitability to reduce potentially interfering Corg. Calibration curves responded linearly (adj. R2 > 0.996) with instrumental detection limits of 1–86 ng corresponding to method detection limits of 1–86 μg g−1. The measurement repeatability was 3.2–7.2 % relative standard deviation. Recoveries of 70–128 % were achieved for plastic contents of 250 μg g−1 extracted with TCB without prior cleanup from soils with less than 2.5 % Corg. A higher Corg particularly interfered with the quantification of PE. The addition of non-target polymers (polyethylene terephthalate, polyvinyl chloride, poly(methyl methacrylate), and tire wear particles) did not interfere with the quantification of the analytes highlighting the selectivity of the method. Further research is needed to determine low plastic contents in soils exceeding 2.5 % Corg. With 1–3 h processing time per sample, our method has the potential for routine analyses and screening studies of agricultural systems to be complemented with microspectroscopic techniques for additional information on particle shapes and sizes.
The lack of adequate analytical methods for the quantification of plastic debris in soil challenges a better understanding of their occurrence and fate in the terrestrial environment. With this proof-of-principle study, we developed a simple and fast method for the selective quantification of the three most environmentally relevant polymers polyethylene (PE), polypropylene (PP), and polystyrene (PS) in soil using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In order to facilitate the preparation of calibration series and to better account for the heterogeneity of soil matrix, polymers were dissolved in 1,2,4-trichlorobenzene (TCB) at 120 °C. Thereby, liquid sample aliquots from up to 4 g of solid sample became amenable to pyrolysis without further preparation. To evaluate the performance of this approach, three reference soils with 1.73–5.16 % organic carbon (Corg) were spiked at 50 and 250 μg g−1 of each polymer and extracted with TCB. A prior cleanup step with methanol, flocculation with KAl(SO4)2, and Fenton digestion were tested for their suitability to reduce potentially interfering Corg. Calibration curves responded linearly (adj. R2 > 0.996) with instrumental detection limits of 1–86 ng corresponding to method detection limits of 1–86 μg g−1. The measurement repeatability was 3.2–7.2 % relative standard deviation. Recoveries of 70–128 % were achieved for plastic contents of 250 μg g−1 extracted with TCB without prior cleanup from soils with less than 2.5 % Corg. A higher Corg particularly interfered with the quantification of PE. The addition of non-target polymers (polyethylene terephthalate, polyvinyl chloride, poly(methyl methacrylate), and tire wear particles) did not interfere with the quantification of the analytes highlighting the selectivity of the method. Further research is needed to determine low plastic contents in soils exceeding 2.5 % Corg. With 1–3 h processing time per sample, our method has the potential for routine analyses and screening studies of agricultural systems to be complemented with microspectroscopic techniques for additional information on particle shapes and sizes.The occurrence of pharmaceutical waste in different parts of the world: A scoping reviewhttps://peerj.com/preprints/279512019-09-102019-09-10Kim Yun JinMuhammad Shahzad Aslam
Pharmaceutical waste in our ecosystem is the huge burden for our future generations, especially in developing countries. It can be in every place even in drinking water after water treatment. It was observed the presence of over the counter drugs such as ibuprofen, naproxen, acetaminophen and antibiotic such as sulfamethoxazole, trimethoprim, erythromycin the most in the environment. Among all result, Carbamazepine which is known to treat epilepsy was found the most in the environment when the results were compiled from different parts of the world due to its low biodegradable properties. The current article is focused on the occurrence of pharmaceutical waste in the last eight years (January 2010- July 2018) published research work.
Pharmaceutical waste in our ecosystem is the huge burden for our future generations, especially in developing countries. It can be in every place even in drinking water after water treatment. It was observed the presence of over the counter drugs such as ibuprofen, naproxen, acetaminophen and antibiotic such as sulfamethoxazole, trimethoprim, erythromycin the most in the environment. Among all result, Carbamazepine which is known to treat epilepsy was found the most in the environment when the results were compiled from different parts of the world due to its low biodegradable properties. The current article is focused on the occurrence of pharmaceutical waste in the last eight years (January 2010- July 2018) published research work.Is there an empirical environmental Kuznets curve relationship between mismanaged plastic waste per capita and income per capita? A caveathttps://peerj.com/preprints/278832019-08-032019-08-03Takuro UeharaMateo Cordier
A study by Barnes (2019) concluded that there exists an empirical environmental Kuznets curve (EKC) relationship between mismanaged plastic waste per capita and income per capita. However, this result needs careful interpretation. The study adopted data that used the World Bank database to compute mismanaged plastic waste amounts. Because data to compute them were not available for all countries, missing data were estimated by relating them to economic classification (i.e., income level). In other words, the data used for the analysis by Barnes simply assumed—without scientific validation—that mismanaged plastic waste amounts are related to economic classification (i.e., income level).
A study by Barnes (2019) concluded that there exists an empirical environmental Kuznets curve (EKC) relationship between mismanaged plastic waste per capita and income per capita. However, this result needs careful interpretation. The study adopted data that used the World Bank database to compute mismanaged plastic waste amounts. Because data to compute them were not available for all countries, missing data were estimated by relating them to economic classification (i.e., income level). In other words, the data used for the analysis by Barnes simply assumed—without scientific validation—that mismanaged plastic waste amounts are related to economic classification (i.e., income level).Designing a bioremediator: mechanistic models guide cellular and molecular specializationhttps://peerj.com/preprints/278382019-07-032019-07-03Marco ZaccariaWilliam DawsonViviana CristiglioMassimo ReverberiLaura E. RatcliffTakahito NakajimaLuigi GenoveseBabak Momeni
Rational, mechanistic design can substantially improve the performance of bioremediators for applications including waste treatment and food safety. We highlight how such improvement can be informed at the cellular level by theoretical observations especially in the context of phenotype plasticity, cell signaling, and community assembly. At the molecular level, we suggest enzyme design using techniques such as Small Angle Neutron Scattering and Density Functional Theory. To provide an example of how these techniques could be synergistically combined, we present the case-study of the interaction of the enzyme laccase with the food pollutant aflatoxin B1. In designing bioremediators, we encourage interdisciplinary, mechanistic research to transition from an observation-oriented approach to a principle-based one.
Rational, mechanistic design can substantially improve the performance of bioremediators for applications including waste treatment and food safety. We highlight how such improvement can be informed at the cellular level by theoretical observations especially in the context of phenotype plasticity, cell signaling, and community assembly. At the molecular level, we suggest enzyme design using techniques such as Small Angle Neutron Scattering and Density Functional Theory. To provide an example of how these techniques could be synergistically combined, we present the case-study of the interaction of the enzyme laccase with the food pollutant aflatoxin B1. In designing bioremediators, we encourage interdisciplinary, mechanistic research to transition from an observation-oriented approach to a principle-based one.Lead isotope trends and sources in the atmosphere at an artificial wetlandhttps://peerj.com/preprints/277642019-05-292019-05-29Ling CongJiexiu ZhaiGuoxin YanJiakai LiuYanan WuYu WangZhenming ZhangMingxiang Zhang
With the rapid development of industry, studies on lead pollution in total suspended particulate matter (TSP) have received extensive attention. This paper analyzed the concentration and pollution sources of lead in the Cuihu Wetland in Beijing during the period of 2016–2017. The results show that the lead contents in TSP in the Cuihu Wetland were approximately equal in summer and spring, greater in winter, and greatest in autumn. The corresponding lead concentrations were 0.052 ng/m3, 0.053 ng/m3, 0.101 ng/m3, and 0.115 ng/m3, respectively. We compared the 206Pb/207Pb data with other materials to further understand the potential sources of atmospheric lead. The mean values of 206Pb/207Pb from spring to winter were 1.082, 1.098, 1.092, and 1.078, respectively. We found that the lead sources may be associated with coal burning, brake and tire wear, and vehicle exhaust emissions. We also calculated the enrichment factor values for the four seasons, and the values were all much greater than 10, indicating that the lead pollution is closely related to human activities.
With the rapid development of industry, studies on lead pollution in total suspended particulate matter (TSP) have received extensive attention. This paper analyzed the concentration and pollution sources of lead in the Cuihu Wetland in Beijing during the period of 2016–2017. The results show that the lead contents in TSP in the Cuihu Wetland were approximately equal in summer and spring, greater in winter, and greatest in autumn. The corresponding lead concentrations were 0.052 ng/m3, 0.053 ng/m3, 0.101 ng/m3, and 0.115 ng/m3, respectively. We compared the 206Pb/207Pb data with other materials to further understand the potential sources of atmospheric lead. The mean values of 206Pb/207Pb from spring to winter were 1.082, 1.098, 1.092, and 1.078, respectively. We found that the lead sources may be associated with coal burning, brake and tire wear, and vehicle exhaust emissions. We also calculated the enrichment factor values for the four seasons, and the values were all much greater than 10, indicating that the lead pollution is closely related to human activities.Microplastics pollution in the South American Pantanalhttps://peerj.com/preprints/277542019-05-232019-05-23Erika de FariaPierre GirardCarolina S NardesAndressa MoreschiSusete W ChristoAugusto Luiz Ferreira JuniorMonica F Costa
Microplastics represent an emerging global threat to freshwater ecosystems and studies in floodplains are still incipient. Microplastics in the Pantanal’s affluent and floodplains were sampled close to their potential urban sources and in the Pantanal lowlands. A 68 μm mesh size plankton net, with a 150 ml collection flask was used for sampling. The flask content was filtered over a 0.45μm Whatman paper, 47 mm in diameter, and examined under a stereomicroscope at 45X to identify and count microplastics (expressed as n100L-1). Microplastic sizes were determined by image microscopy. The average microplastic size was 192±142 μm and it was not significantly different in the urban tributaries (206±158 μm) than in the Pantanal (181±131 μm). The average±std microplastic concentration was 9.6±8.3, ranging from 1 to 31 n100L-1. Fibers, fragments, pellets, and XPS (closed-cell extruded polystyrene foam) particles represented respectively 50%, 19%, 22% and 9% of the total microplastics. Microplastics concentrations were higher in the urban tributaries (19.9±5.8 n100L-1) than in the Pantanal lowlands (4.5±2.5 n100L-1). Fibers were always the most important fraction, followed by fragments. In the lowlands, pellets were scarce and XPS were absent. Comparison between microplastic composition in the floodplain and the urban areas suggest that pellets are transported from the urban area to the Pantanal, while microfibers and fragments could both be transported from the urban areas and have a local origin. These results indicate that microplastics are contaminating the Pantanal and its affluents and eventually can affect the local fauna. More research is needed to understand the extent and possible implications regarding the contamination by microplastics of the aquatic and terrestrial ecosystems of the Pantanal.
Microplastics represent an emerging global threat to freshwater ecosystems and studies in floodplains are still incipient. Microplastics in the Pantanal’s affluent and floodplains were sampled close to their potential urban sources and in the Pantanal lowlands. A 68 μm mesh size plankton net, with a 150 ml collection flask was used for sampling. The flask content was filtered over a 0.45μm Whatman paper, 47 mm in diameter, and examined under a stereomicroscope at 45X to identify and count microplastics (expressed as n100L-1). Microplastic sizes were determined by image microscopy. The average microplastic size was 192±142 μm and it was not significantly different in the urban tributaries (206±158 μm) than in the Pantanal (181±131 μm). The average±std microplastic concentration was 9.6±8.3, ranging from 1 to 31 n100L-1. Fibers, fragments, pellets, and XPS (closed-cell extruded polystyrene foam) particles represented respectively 50%, 19%, 22% and 9% of the total microplastics. Microplastics concentrations were higher in the urban tributaries (19.9±5.8 n100L-1) than in the Pantanal lowlands (4.5±2.5 n100L-1). Fibers were always the most important fraction, followed by fragments. In the lowlands, pellets were scarce and XPS were absent. Comparison between microplastic composition in the floodplain and the urban areas suggest that pellets are transported from the urban area to the Pantanal, while microfibers and fragments could both be transported from the urban areas and have a local origin. These results indicate that microplastics are contaminating the Pantanal and its affluents and eventually can affect the local fauna. More research is needed to understand the extent and possible implications regarding the contamination by microplastics of the aquatic and terrestrial ecosystems of the Pantanal.Deep transcriptomic analysis of Chromera velia under Mercury-stress conditionhttps://peerj.com/preprints/277502019-05-222019-05-22Abdoallah SharafRoberto De MicheleAyush SharmaMiroslav Oborník
The heavy metal pollution in ecosystems is of increasing global concern. The main sources of the metal toxicity are the industrial waste, mining and the use of pesticides containing heavy metals. Out of all heavy metals, mercury (Hg) is considered to be the one, easily accumulated in terrestrial plants as well as aquatic organism. Hg can induce more severe oxidative stress by triggering the production of reactive oxygen species (ROS) and damage macro-molecules. ROS serve not only as dangerous molecules that damage proteins, lipids and DNA but also as signalling molecules in the regulation of biological processes such as biotic and abiotic stress responses, growth and development. This study shows the change in the Chromera velia transcriptome due to Hg stress. C. velia is the recently discovered closest known relative of apicomplexans. Our study shows the first deep transcriptomic analysis of C. velia, specifically focusing on the expression level of the genes involved in detoxification defence systems under heavy metal stress. The results show that in total 1239 genes are differentially expressed. DEGs (Differentially expressed genes) showed overall up-regulation (1,070 genes) and only 169 up-regulated genes in cultures under Mercury stress (Cvel_mer) when compared to the control level (Cvel_cont). The qPCR expression analysis exhibited a positive correlation with the findings of RNA-seq data.
The heavy metal pollution in ecosystems is of increasing global concern. The main sources of the metal toxicity are the industrial waste, mining and the use of pesticides containing heavy metals. Out of all heavy metals, mercury (Hg) is considered to be the one, easily accumulated in terrestrial plants as well as aquatic organism. Hg can induce more severe oxidative stress by triggering the production of reactive oxygen species (ROS) and damage macro-molecules. ROS serve not only as dangerous molecules that damage proteins, lipids and DNA but also as signalling molecules in the regulation of biological processes such as biotic and abiotic stress responses, growth and development. This study shows the change in the Chromera velia transcriptome due to Hg stress. C. velia is the recently discovered closest known relative of apicomplexans. Our study shows the first deep transcriptomic analysis of C. velia, specifically focusing on the expression level of the genes involved in detoxification defence systems under heavy metal stress. The results show that in total 1239 genes are differentially expressed. DEGs (Differentially expressed genes) showed overall up-regulation (1,070 genes) and only 169 up-regulated genes in cultures under Mercury stress (Cvel_mer) when compared to the control level (Cvel_cont). The qPCR expression analysis exhibited a positive correlation with the findings of RNA-seq data.Whole genome sequencing of a novel, dichloromethane-fermenting Peptococcaceae from an enrichment culturehttps://peerj.com/preprints/277182019-05-102019-05-10Sophie I HollandRichard J EdwardsHaluk ErtanYie Kuan WongTonia L RussellNandan P DeshpandeMichael ManefieldMatthew J Lee
Bacteria capable of dechlorinating the toxic environmental contaminant dichloromethane (DCM, CH2Cl2) are of great interest for potential bioremediation applications. A novel, strictly anaerobic, DCM-fermenting bacterium, "DCMF", was enriched from organochlorine-contaminated groundwater near Botany Bay, Australia. The enrichment culture was maintained in minimal, mineral salt medium amended with dichloromethane as the sole energy source. PacBio whole genome SMRTTM sequencing of DCMF allowed de novo, gap-free assembly despite the presence of cohabiting organisms in the culture. Illumina sequencing reads were utilised to correct minor indels. The single, circularised 6.44 Mb chromosome was annotated with the IMG pipeline and contains 5,773 predicted protein-coding genes. Based on 16S rRNA gene and predicted proteome phylogeny, the organism appears to be a novel member of the Peptococcaceae family. The DCMF genome is large in comparison to known DCM-fermenting bacteria and includes 96 predicted methylamine methyltransferases, which may provide clues to the basis of its DCM metabolism. Full annotation has been provided in a custom genome browser and search tool, in addition to multiple sequence alignments and phylogenetic trees for every predicted protein, available at http://www.slimsuite.unsw.edu.au/research/dcmf/.
Bacteria capable of dechlorinating the toxic environmental contaminant dichloromethane (DCM, CH2Cl2) are of great interest for potential bioremediation applications. A novel, strictly anaerobic, DCM-fermenting bacterium, "DCMF", was enriched from organochlorine-contaminated groundwater near Botany Bay, Australia. The enrichment culture was maintained in minimal, mineral salt medium amended with dichloromethane as the sole energy source. PacBio whole genome SMRTTM sequencing of DCMF allowed de novo, gap-free assembly despite the presence of cohabiting organisms in the culture. Illumina sequencing reads were utilised to correct minor indels. The single, circularised 6.44 Mb chromosome was annotated with the IMG pipeline and contains 5,773 predicted protein-coding genes. Based on 16S rRNA gene and predicted proteome phylogeny, the organism appears to be a novel member of the Peptococcaceae family. The DCMF genome is large in comparison to known DCM-fermenting bacteria and includes 96 predicted methylamine methyltransferases, which may provide clues to the basis of its DCM metabolism. Full annotation has been provided in a custom genome browser and search tool, in addition to multiple sequence alignments and phylogenetic trees for every predicted protein, available at http://www.slimsuite.unsw.edu.au/research/dcmf/.Bioremediation of engine-oil contaminated soil using local residual organic matterhttps://peerj.com/preprints/276962019-04-302019-04-30Kawina RobichaudMiriam LebeauSylvain MartineauMarc Amyot
Soil remediation industries continue to seek technologies to speed-up treatment and reduce operating costs. Some processes are energy intensive and, in some cases, transport can be the main source of carbon emissions. Residual fertilizing matter (RFM), such as organic residues, have the potential to be beneficial bioremediation agents. Following a circular economy framework, we investigated the feasibility of sourcing RFMs locally to reduce transport and assess possible bioremediation efficiency gains. RFMs were recruited within 100 km of the treatment site: ramial chipped wood (RCW), horse manure (MANR) and brewer spent grain (BSG). They were added to the land treatment unit’s baseline fertilizer treatment (FERT, ‘F’) to measure if they improved the remediation efficiency of an engine oil-contaminated soil (7500 ± 100 mg kg-1). Results indicate that MANR-F was the only amendment more effective than FERT for PHC reduction, while emitting the least CO2overall. RCW-F was equivalent to FERT but retained more moisture. Although BSG contributed the most nitrogen to the soil, BSG-F retained excessive moisture, emitted more VOCs, contained less soil O2, and was less effective than the baseline treatment. Significantly more of the C16-C22fraction was removed (63 ± 22%) than all other fractions (C22-C28, C28-C34, C34-C40), which were equally removed. Microbial community-level physiological profiling (CLPP) was conducted with Biolog EcoplatesTM, and catabolic diversity differed between treatments (utilization rates of 31 carbon sources). MANR-F has the potential to increase PHC-remediation speed and efficiency compared to inorganic fertilizer alone. Other RFM promote moisture retention and diverse microbial catabolic activity. A variety of RFM are present across the globe and some can offer low-cost amendments to boost remediation efficiency, while reducing treatment time compared to traditional fertilizer-only methods.
Soil remediation industries continue to seek technologies to speed-up treatment and reduce operating costs. Some processes are energy intensive and, in some cases, transport can be the main source of carbon emissions. Residual fertilizing matter (RFM), such as organic residues, have the potential to be beneficial bioremediation agents. Following a circular economy framework, we investigated the feasibility of sourcing RFMs locally to reduce transport and assess possible bioremediation efficiency gains. RFMs were recruited within 100 km of the treatment site: ramial chipped wood (RCW), horse manure (MANR) and brewer spent grain (BSG). They were added to the land treatment unit’s baseline fertilizer treatment (FERT, ‘F’) to measure if they improved the remediation efficiency of an engine oil-contaminated soil (7500 ± 100 mg kg-1). Results indicate that MANR-F was the only amendment more effective than FERT for PHC reduction, while emitting the least CO2overall. RCW-F was equivalent to FERT but retained more moisture. Although BSG contributed the most nitrogen to the soil, BSG-F retained excessive moisture, emitted more VOCs, contained less soil O2, and was less effective than the baseline treatment. Significantly more of the C16-C22fraction was removed (63 ± 22%) than all other fractions (C22-C28, C28-C34, C34-C40), which were equally removed. Microbial community-level physiological profiling (CLPP) was conducted with Biolog EcoplatesTM, and catabolic diversity differed between treatments (utilization rates of 31 carbon sources). MANR-F has the potential to increase PHC-remediation speed and efficiency compared to inorganic fertilizer alone. Other RFM promote moisture retention and diverse microbial catabolic activity. A variety of RFM are present across the globe and some can offer low-cost amendments to boost remediation efficiency, while reducing treatment time compared to traditional fertilizer-only methods.