Restoration Sites Research Articles

Building the Nation in Stone and Wood. Restorations and Writings about Historical Monuments in the First Half of the Twentieth Century in Romania

The paper looks at restoration and preservation practices and at art history writings to explore attitudes and mentalities in the first decades of the twentieth century in Romania. It deciphers the creation of an architectural heritage and the meanings of writings about and restoring historical monuments in a young nation-state that expanded significantly after World War I. Some of the major restoration sites in Romania, around 1900, are analysed together with several of the architectural history writings of the interwar period that reveal a growing turn to nationalism in the Romanian cultural and political spheres.

Mine Site Restoration: The Phytoremediation of Arsenic-Contaminated Soils

Arsenic (As) is considered one of the most toxic chemicals to both human and environmental health. Mining activities represent one of the main anthropogenic sources of As; the concentration of As in mine soil can reach 9300 mg kg−1. To overcome the major issue of soil As pollution, soil restoration is required. Biological restoration approaches are generally more cost-effective and environmentally sustainable than physical and chemical methods. In particular, phytoremediation, an environmentally friendly technique based on the use of plants to uptake contaminants from soil, has been successfully implemented to restore As-contaminated soils at mine sites. However, mine soils are generally depleted in essential plant nutrients, such as nitrogen (N). Recent research suggests that phytoremediation can be combined with other techniques (physical, chemical, and biological) to enhance the N content and plant biomass. The aim of this review is to assess the current state of knowledge in the field of the restoration of arsenic-impacted mine site soils, focusing on phytoremediation. We critically assess recent work examining the potential of the co-application of amendments with phytoremediation and identify promising technologies and key research gaps. More studies are required to test the effectiveness of using various soil additives to enhance the phytoremediation of As, not only in pot-scale experiments but also in the field, to enable an improved management strategy for mine site restoration in the future.

Restoration age affects microbial-herbaceous plant interactions in an oak woodland.

In degraded ecosystems, soil microbial communities (SMCs) may influence the outcomes of ecological restoration. Restoration practices can affect SMCs, though it is unclear how variation in the onset of restoration activities in woodlands affects SMCs, how those SMCs influence the performance of hard-to-establish woodland forbs, and how different woodland forbs shape SMCs. In this study, we quantified soil properties and species abundances in an oak woodland restoration chronosequence (young, intermediate, and old restorations). We measured the growth of three woodland forb species when inoculated with live whole-soil from young, intermediate, or old restorations. We used DNA metabarcoding to characterize SMCs of each inoculum treatment and the soil after conditioning by each plant species. Our goals were to (1) understand how time since the onset of restoration affected soil abiotic properties, plant communities, and SMCs in a restoration chronosequence, (2) test growth responses of three forb species to whole-soil inoculum from restoration sites, and (3) characterize changes in SMCs before and after conditioning by each forb species. Younger restored woodlands had greater fire-sensitive tree species and lower concentrations of soil phosphorous than intermediate or older restored woodlands. Bacterial and fungal soil communities varied significantly among sites. Forbs exhibited the greatest growth in soil from the young restoration. Each forb species developed a unique soil microbial community. Our results highlight how restoration practices affect SMCs, which can in turn affect the growth of hard-to-establish forb species. Our results also highlight that the choice of forb species can alter SMCs, which could have long-term potential consequences for restoration success.

Nudging to glory: the World Heritage Convention’s influence in conflict-prone Global South natural sites

The paper explores the role of the UNESCO World Heritage Convention in safeguarding natural and cultural heritage, with a specific focus on sites facing armed conflict. The Convention acts as a global mechanism for the protection and conservation of sites with Outstanding Universal Value. The study investigates the use of ‘soft power’ and ‘nudging’ strategies by the World Heritage Committee to facilitate the restoration of World Heritage Sites facing threats, particularly in the Global South. The analysis is based on the examination of 32 natural sites inscribed on the List of World Heritage in Danger since 1984, nine of which are in the Global South and faced with armed conflict. Case studies illustrate how armed conflicts impact biodiversity and the steps taken to recover these sites. The study emphasises the soft power of the World Heritage Convention, backed by diplomatic ties and financial aid, as instrumental in achieving restoration. Nudging is observed in the strategic alignment of choices to encourage conservation efforts. The findings suggest that the World Heritage Committee’s influence extends beyond conservation, contributing to regional development, especially in the Global South. However, challenges persist, and the paper calls for a continuous evolution of the World Heritage Convention’s role in addressing conflicts, development, and climate change to ensure effective global heritage conservation.

Exploring the influence of ground-dwelling ant bioturbation activity on physico-chemical, biological properties and heavy metal pollution in coal mine spoil

Coal mining activities increase the soil concentrations of heavy metals manifold thus impacting soil health and biodiversity. The understanding of the impact of bioturbation activities by ant colonies on soil in coal mine spoil site across different restoration ages is not studied. The study aimed to investigate the influence of bioturbation activities by two most common and distinct coal mine site inhabiting ant species (C. compressus and C. longipedem) at six different ages (2, 4, 6, 8, 10 and 12 years old) on the soil heavy metal concentrations of Fe, Zn, Mn, Cu, Ni, Pb, Cd and Cr, pH, OM, TC, TN, soil enzyme activity of DH, ACP, β-glucosidase and proteases properties of soil. Soil samples were collected from opencast coalmine spoils during October and November 2017. Reference (Ref.) soil samples (n=10 per site) were collected (from area adjacent to ant nest colony approximately 2–5 m distance) from a depth of 0–15 cm and ant nest debris soil of each ant species (n=10 per site) were collected from each site. Heavy metal pollution decreased and pH, OM, TC, TN and soil enzyme activity of DH, ACP, β-glucosidase and proteases of soil in both Ref. soil and ant nest debris soil increases with the increase of mine site restoration age. Our study revealed that different age of the mine spoil have more profound effects on the soil quality and heavy metal content. Contrary to our hypothesis, regression analysis did not support our notion that ant bioturbation activity directly accelerate heavy metal breakdown. Instead, our findings suggests that ant colonies prefer to construct their nest for the locations with lower heavy metal concentrations and higher enzyme activity and increase in soil porosity is a key factor behind the low heavy metal concentration in the nest debris soil.

Upscaling marine forest restoration: challenges, solutions and recommendations from the Green Gravel Action Group

IntroductionTo counteract the rapid loss of marine forests globally and meet international commitments of the UN Decade on Ecosystem Restoration and the Convention on Biological Diversity ‘30 by 30’ targets, there is an urgent need to enhance our capacity for macroalgal restoration. The Green Gravel Action Group (GGAG) is a global network of 67 members that are working on the restoration of a diverse range of macroalgal forests and it aims to facilitate knowledge exchange to fast-track innovation and implementation of outplanting approaches worldwide.MethodsHere, we overview 25 projects conducted by members of the group that are focused on testing and developing techniques for macroalgal restoration. Based on these projects, we summarise the major challenges associated with scaling up the area of marine forests restored.ResultsWe identify several critical challenges that currently impede more widespread rollout of effective large-scale macroalgal restoration worldwide: 1) funding and capacity limitations, 2) difficulties arising from conditions at restoration sites, 3) technical barriers, and 4) challenges at the restoration-policy interface.DiscussionDespite these challenges, there has been substantial progress, with an increasing number of efforts, community engagement and momentum towards scaling up activities in recent years. Drawing on the collective expertise of the GGAG, we outline key recommendations for the scaling up of restoration efforts to match the goals of international commitments. These include the establishment of novel pathways to fund macroalgal restoration activities, building skills and capacity, harnessing emerging innovations in mobile hatchery and seeding technologies, and the development of the scientific and governance frameworks necessary to implement and monitor macroalgal restoration projects at scale.

Selecting Suitable Tree Species for Direct Seeding to Restore Forest Ecosystems in Northern Thailand

To upscale restoration of tropical forest ecosystems, direct seeding—sowing seeds directly into the ground—is potentially a more cost-effective technique than tree planting. However, its success is limited by seed predation, the harshness of environmental conditions on restoration sites and particularly by a lack of information about suitable tree species. Therefore, this study tested the suitability of 23 native forest tree species for direct seeding, to restore a biodiversity-rich, upland, evergreen forest in northern Thailand. Three replicate seed batches of each species were sown randomly in two degraded sites and in a tree nursery under controlled conditions. Seed removal and germination were monitored weekly until no further germination had occurred for more than a month. Subsequently, seedling yield, growth and species performance score were also monitored at appropriate intervals. Nine months after sowing, seed removal differed significantly among species but was generally low, with a cross-species average of 3.4% (±0.5 SE). Seed size was negatively correlated with seed removal. Eight species failed to germinate. Seed germination percentage varied widely among species. Cross-species average germination of the 15 species that germinated was 25% (±6.2 SE). Two species (Adenanthera microsperma and Alangium kurzii) were ranked as having high germination (>50%), five species (Choerospondias axillaris, Spondias pinnata, Diospyros glandulosa, Melia azedarach and Phyllanthus emblica) had medium germination (20–50%) and eight species had low germination (<20%). Following the first dry season, two of the fifteen germinated species failed to establish. Germination and establishment were influenced by seed size, seed storage behavior and successional status. A. microsperma, S. pinnata and C. axillaris are recommended for direct seeding based on their high species performance index values. This study further concluded that selecting desiccation-tolerant seeds, particularly those with medium-to-large sizes, could increase the chances of successful seedling establishment.

Vegetation diversity and structure influence small‐mammal communities in native and restored northern mixed grasslands

AbstractCurrent grassland restoration strategies aim to recreate grassland vegetation communities, and often rely on high‐diversity native seeding to promote vegetation diversity. Questions remain concerning the influence of vegetation richness and diversity on grassland fauna. Small‐mammal communities are integral parts of grassland ecosystems, but their responses to restoration are often mixed or overlooked. During July 2014 to 2016, we used Sherman live traps to survey grassland small‐mammal communities of 24 study sites in northeastern South Dakota and southeastern North Dakota, USA, to better understand their responses to vegetation cover type, diversity, richness, and site‐specific vegetation structure. Sites represented a vegetation species richness gradient and 3 vegetation cover types including low‐diversity restorations planted with dense nesting cover (DNC) seed mix, high‐diversity seeded restorations, and unseeded reference grasslands. Small‐mammal abundance was highest at low‐diversity DNC restoration sites and lowest in reference grassland. Small‐mammal diversity was highest at high‐diversity restoration sites and lowest at low‐diversity DNC restoration sites. Models assessing the influence of vegetation structure on the abundance of focal taxa differed. Deer mice (Peromyscus spp.) were negatively influenced by percent native vegetation cover, and voles (Microtus spp.) showed yearly variation and were influenced positively by litter depth and negatively by vegetation richness. Small‐mammal communities of low‐diversity DNC restorations differed from reference sites, but high‐diversity restorations were not different from reference or low‐diversity DNC sites. Thirteen‐lined ground squirrel (Ictidomys tridecemlineatus) abundance was higher at reference and high‐diversity restored sites, while low‐diversity DNC sites had higher deer mice abundance. Results indicate small mammals are unlikely to respond uniformly to vegetation characteristics, and diversity of seed mixes used in grassland restoration is likely to influence grassland small‐mammal communities.

Ecological restoration at the University of Wisconsin–Madison Arboretum and beyond: Building and sharing collective knowledge through a participatory leadership framework

Abstract The Society for Ecological Restoration defines restoration as “the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed.” The United Nations Decade on Ecosystem Restoration is an “all‐hands‐on‐deck” call to revive imperilled ecosystems around the world. The task at hand is more than professional practitioners and organizations can handle alone. Volunteers play a critically important role in restoring the structure and function of the world's most degraded ecosystems. The 485 ha University of Wisconsin–Madison Arboretum is the site of some of the oldest restored ecological communities in the world. Like many restoration sites, long‐term management of these communities requires expertise and sustained volunteer engagement. The Arboretum fosters expertise and engagement with a two‐pronged approach. This includes (1) the Arboretum's Restoration Team Leader Program, which trains and empowers restoration volunteers to lead community members in on‐the‐ground restoration, and (2) the Restoration Managers Who Work with Volunteers group that convenes restoration managers from multiple organizations for collaborative projects. These programs facilitate ecological restoration by working directly with volunteers and are models of participatory leadership and communities of practice. Here, we share the principles, practices and frameworks behind these programs and illustrate how this model can be replicated to strengthen community‐based restoration around the globe.

Effects of the addition of slaked lime to alkali-activated pastes based on volcanic ashes from Mt. Etna volcano (Italy)

This study provides experimental insights into the optimization of alkali-activated materials (AAMs) carried out in situ at the restoration site of Monreale Cathedral, Italy. Volcanic ash from Mt. Etna volcano (Italy) was used as a precursor to obtain AAMs. Standard and modified pastes with a small amount of slaked lime paste were compared in terms of setting time, rheology, mineralogy, chemical morphology, and mechanical performance. The modified pastes exhibited a faster setting time, superior mechanical strength and rheological properties. Mineralogically, no difference was observed between the two pastes for the small amount of slaked lime paste added very close to the detectable limit (<2 wt%). Moreover, its addition causes slight differences in the morphology of the gel without changing the chemical composition of the Na2O–CaO–Al2O3–SiO2–H2O ((N,C)-A-S-H)) type. The results obtained may be useful for the development and optimization of building materials (especially for restoration purposes) where appropriate physico-mechanical performance is required.

A multi‐metric index for assessing two decades of community responses to broad‐scale shoreline enhancement and restoration along the Toronto waterfront

Abstract Biodiversity and habitat loss due to historical and continued urbanization and anthropogenic development require continuous efforts to abate ongoing environmental decline. Restoration and enhancement efforts that aim to address biodiversity and habitat loss, have shown some promise at providing suitable habitat for species in the more urbanized nearshore areas of Lake Ontario. Using 20 years of fish community data from the Toronto waterfront, this study examined ecosystem responses in a spatio‐temporal context across wetland and embayment ecotypes. The goals of this study were to (1) assess how fish communities have changed over time in restored, reference and more and less urbanized nearshore ecosystems and (2) determine if restored and enhanced habitats meet the defined fish community management targets. Fish communities were assessed through a newly developed multi‐metric index based on species life history traits and habitat associations like trophic and thermal guild. Fish communities along the waterfront have transitioned from cool and coldwater pelagic species to a higher proportion of native warmwater species, many of them piscivores, associated with cover and vegetation, that meet community targets. These changes are more pronounced at the largest restoration site ‘Tommy Thompson Park’, where community indices approach natural reference levels. This result indicates the benefits and effectiveness of the decade‐long restoration efforts and subsequent monitoring of responses. Our results underline that large‐scale restoration projects in urbanized settings can be of vital importance for freshwater conservation efforts, as well as application scenarios for multi‐metric community indices, and will play an even larger role when looking at Lake Ontario or the Great Lakes as a whole.

Natural Environments in University Campuses and Students' Well-Being.

Most recent university campuses follow the North American model, built on city limits or countryside, with large separate buildings in open green spaces. Studies suggest that the prevalence and severity of mental health issues among university students has been increasing over the past decade in most countries. University services were created to face this growing problem, however individual-based interventions have limited effects on mental health and well-being of a large population. Our aim was to verify if and how the natural environment in campuses is focused on programs to cope with the issue of mental health and well-being among students. A systematic review of literature was undertaken with search in Scopus and LILACS with the keywords "green areas" AND "well-being" AND "Campus", following PRISMA guidelines. As a result, 32 articles were selected. Research on the topic is recent, mostly in the USA, Bulgaria, and China. Most studies used objective information on campuses' greenness and/or university students' perception. Mental health was usually measured by validated scores. Findings of all the studies indicated positive association between campus greenery and well-being of students. We conclude that there is a large potential for use of university campuses in programs and as sites for students' restoration and stress relief.

Comparing the Response of Red Spruce Plantings on Legacy Coal Mines and Old-Field Restoration Sites in the West Virginia Highlands

Comparing the Response of Red Spruce Plantings on Legacy Coal Mines and Old-Field Restoration Sites in the West Virginia Highlands

Relative contributions of osteal macrophages and osteoclasts to postnatal bone development in CSF1R-deficient rats and phenotype rescue following wild-type bone marrow cell transfer.

Macrophage and osteoclast proliferation, differentiation and survival are regulated by colony-stimulating factor-1 receptor (CSF1R) signaling. Osteopetrosis associated with Csf1 and Csf1r mutations has been attributed to the loss of osteoclasts and deficiency in bone resorption. Here we demonstrate that homozygous Csf1r mutation in rat leads to delayed postnatal skeletal ossification associated with substantial loss of osteal macrophages (osteomacs) in addition to osteoclasts. Osteosclerosis and site-specific skeletal abnormalities were reversed by intraperitoneal transfer of wild-type bone marrow cells (BMT) at weaning. Following BMT, IBA1+ macrophages were detected before TRAP+ osteoclasts at sites of ossification restoration. These observations extend evidence that osteomacs independently contribute to bone anabolism and are required for normal postnatal bone growth and morphogenesis.

Assessing coastal vulnerability and climate resilience for Caribbean small island states using ecological principles

Climate Change challenges small island developing nations (SIDS) whose economies are heavily dependent on touristic coastal development. Climate change, as a driver of coastal impacts, is manifested by increased storm intensity as well as sea level rise. The intersection of climate hazards, exposure and vulnerability is the overall risk of coastal impacts. Ecological principles can be applied to simple Coastal Indices (CVI) to establish priorities for mitigation focused on risky development areas to direct population growth to lower risk areas. This research examines one island within the Bahamian archipelago to demonstrate how ecological principles can be applied to quantify vulnerability and recommend high-priority sites for restoration or remediation. This study aims to quantify vulnerability of coastlines through an assessment of coastal vegetation setbacks, intact wetlands and coastal geomorphology. The aim is to produce a tool to identify highly vulnerable/highly exposed coastlines that can be specifically targeted for risk reduction through cost-benefit analyses of response options. The vulnerability assessment was quantitative and allowed the ranking of coastal environments on one island to set priorities for remediation of highly vulnerable sites. Tools that identify at-risk coastal areas allow small Caribbean nations more time to adapt their infrastructure and relocate populations.

Short-term restoration practices change the bacterial community in degraded soil from the Brazilian semiarid

Land degradation by deforestation adversely impacts soil properties, and long-term restoration practices have been reported to potentially reverse these effects, particularly on soil microorganisms. However, there is limited knowledge regarding the short-term effects of restoration on the soil bacterial community in semiarid areas. This study evaluates the bacterial community in soils experiencing degradation (due to slash-and-burn deforestation) and restoration (utilizing stone cordons and revegetation), in comparison to a native soil in the Brazilian semiarid region. Three areas were selected: (a) under degradation; (b) undergoing short-term restoration; and (c) a native area, and the bacterial community was assessed using 16S rRNA sequencing on soil samples collected during both dry and rainy seasons. The dry and rainy seasons exhibited distinct bacterial patterns, and native sites differed from degraded and restoration sites. Chloroflexi and Proteobacteria phyla exhibited higher prevalence in degraded and restoration sites, respectively, while Acidobacteria and Actinobacteria were more abundant in sites undergoing restoration compared to degraded sites. Microbial connections varied across sites and seasons, with an increase in nodes observed in the native site during the dry season, more edges and positive connections in the restoration site, and a higher occurrence of negative connections in the degradation site during the rainy season. Niche occupancy analysis revealed that degradation favored specialists over generalists, whereas restoration exhibited a higher prevalence of generalists compared to native sites. Specifically, degraded sites showed a higher abundance of specialists in contrast to restoration sites. This study reveals that land degradation impacts the soil bacterial community, leading to differences between native and degraded sites. Restoring the soil over a short period alters the status of the bacterial community in degraded soil, fostering an increase in generalist microbes that contribute to enhanced soil stability.

Natural regeneration or tree planting in a tropical forest‐to‐pasture damaged area: which is more efficacious for soil ecosystem recovery?

This study assessed whether a natural regeneration or active tree‐planting reforestation strategy better restored the C and N‐cycle processes and associated microbiota within soils after 18 years in a Premontane Wet Life zone site in Monteverde, Costa Rica, compared to adjacent old secondary forest and pasture soils (both &gt;60 years). Our findings apply to small‐scale restoration sites (&lt;0.5 ha plots) commonly used in Monteverde. Both restoration strategies showed recovering soil C and N‐cycle processes with similar levels of TN, NH4+, NO3−, Biomass‐C, and efficiency of organic C use. Both strategies appeared to positively influence the recovery of the levels and community compositional stability of the Actinobacterial, Acidobacterial, N‐fixing (N‐Fixer) bacterial, ammonium‐oxidizing bacterial, and complex organic C‐degrading fungal communities. The main differences between the two strategies were that the tree‐planted and pasture soils had similar compositions of the Actinobacterial, N‐Fixer, and Fungal complex organic C degrader, while the natural regeneration and pasture soils had similar compositions of these groups and the Acidobacteria. However, the community compositions of all five microbial groups were different between restored forest and the old secondary forest soils. These results suggest that while the soil ecosystems from both reforestation strategies are recovering, after 18 years, there is still more recovery to occur. Lastly, possible indicators of post‐restoration soil ecosystem enhancement included increasing constancy of critical microbial group composition, efficiency of organic C conversion to biomass, Biomass‐C, NH4+, NO3−, and levels of Acidothermus, Acidobacteria subgroups 2, 3, and 5, Archaeorhizomyces, Anaeromyxobacter, Bradyrhizobium, Nitrosomonas, Flavobacterium, and Nitrospira.

Evaluating the success of vegetation restoration in rewilded salt marshes

Floodbank realignment is a common practice aimed at restoring salt marsh vegetation on previously embanked land. However, experiences indicate that it may take several years before salt marsh vegetation becomes fully established. Various challenges arising from ecogeomorphic feedback mechanisms could pose significant setbacks to vegetation recolonization. The widespread adoption of transplantation techniques for the restoration and rehabilitation of rewilded landscapes has indeed proven to be a valuable tool for accelerating plant development. In the Ria Formosa coastal lagoon (South of Portugal), a pilot plan was implemented, and two salt marsh pioneer species, Spartina maritima (syn. Sporobolus maritimus) and Sarcocornia perennis (syn. Salicornia perennis), were transplanted from a natural salt marsh to a rewilded marsh. Biodegradable 3D porous structures were installed to mimic transplant clumping, aid sedimentation, and enhance the plant's initial adjustment. Ecological, sediment, and hydrodynamic data were collected during the 12-month pilot restoration plan. The environmental profiles of the donor and restoration sites were compared to substantiate the success of the transplants in the rewilded salt marsh.Results show that although plant shoot density decreased after the transplanting, Spartina maritima acclimated well to the new environmental conditions of the restoration site, showing signs of growth and cover increase, whilst Sarcocornia perennis was not able to acclimatize and survive in the restoration site. The failure behind the Sarcocornia perennis acclimation might be related to the bed properties and topographic properties of the restoration site in the rewilded marsh. Major findings contribute to a more comprehensive understanding of how salt marsh pioneering vegetation successfully colonizes disturbed habitats, facilitated using 3D-biodegradable structures.

Cropland abandonment between 1986 and 2018 across the United States: spatiotemporal patterns and current land uses

Knowing where and when croplands have been abandoned or otherwise removed from cultivation is fundamental to evaluating future uses of these areas, e.g. as sites for ecological restoration, recultivation, bioenergy production, or other uses. However, large uncertainties remain about the location and time of cropland abandonment and how this process and the availability of associated lands vary spatially and temporally across the United States. Here, we present a nationwide, 30 m resolution map of croplands abandoned throughout the period of 1986–2018 for the conterminous United States (CONUS). We mapped the location and time of abandonment from annual cropland layers we created in Google Earth Engine from 30 m resolution Landsat imagery using an automated classification method and training data from the U.S. Department of Agriculture Cropland Data Layer. Our abandonment map has overall accuracies of 0.91 and 0.65 for the location and time of abandonment, respectively. From 1986 to 2018, 12.3 (±2.87) million hectares (Mha) of croplands were abandoned across CONUS, with areas of greatest change over the Ogallala Aquifer, the southern Mississippi Alluvial Plain, the Atlantic Coast, North Dakota, northern Montana, and eastern Washington state. The average annual nationwide abandoned area across our study period was 0.51 Mha per year. Annual abandonment peaked between 1997 and 1999 at a rate of 0.63 Mha year−1, followed by a continuous decrease to 0.41 Mha year−1 in 2009–2011. Among the abandoned croplands, 53% (6.5 Mha) changed to grassland and pasture, 18.6% (2.28 Mha) to shrubland and forest, 8.4% (1.03 Mha) to wetlands, and 4.6% (0.56 Mha) to non-vegetated lands. Of the areas that we mapped as abandoned, 19.6% (2.41 Mha) were enrolled in the Conservation Reserve Program as of 2020. Our new map highlights the long-term dynamic nature of agricultural land use and its relation to various competitive pressures and land use policies in the United States.

Enhancing stability and odor control of water-based foam for pesticide site restoration using xanthan gum

Foam stability plays an important role in the effect of blocking the odorous substances. Based on the characteristic of xanthan gum of enhancing foam stability and preventing foam from water drainage and coarsening, this paper investigated the half-life, foaming volume, viscosity, drainage curve, and bubble microstructure of foam filled with 0.1%, 0.2%, and 0.3% xanthan gum respectively, and further analyzed the correlation between xanthan gum dosage, viscosity of foam solution and foam stability. The effect of different stability foams on para-xylene was tested. The results showed that compared with no xanthan gum, the half-life of foam with 3% xanthan gum was extended from 1 to 61 h, the drainage time increased from 4.5 to 85 h, and the foaming coarsening rate slowed down 3 times. The addition of 0.3% xanthan gum reduced the peak value of the p-xylene dispersion by 83.7% and postponed the peak time by 6 times.