Restored Landfill Sites Research Articles

Earthworms and soil mesofauna as early bioindicators for landfill restoration

Context Landfill activities physically disrupt soil habitats. When restoring landfill to ‘soft’ end uses such as woodland, the appropriate stockpiling and reapplication of native topsoil to provide suitable soil habitats may enhance soil fauna recolonisation and reduce restoration timeframes. Aims We studied the influence of reclamation practices on earthworm and mesofauna communities, and evaluated the role of earthworms and soil mesofauna as bioindicators of early landfill restoration success. Methods We investigated soil physico–chemical parameters, and earthworm and soil mesofauna communities at two restored landfill sites and the surrounding land uses. We also applied the QBS-collembola (QBS-c) and QBS-earthworm (QBS-e) index techniques in a reclaimed landfill setting. Results Natural colonisation of reclaimed landfill by earthworms occurred rapidly where original site topsoil was stockpiled, reapplied, and revegetated. QBS-e and QBS-c indices indicated that the most disturbed sites generally had the lowest soil biological quality. Mesofauna richness and abundance were generally higher in the low-disturbance sites. Conclusions and implications We demonstrate the value of recording a range of soil invertebrates during land reclamation, since different soil bioindicator groups respond differently to soil disturbance. QBS-c and QBS-e index techniques alongside traditional soil macro- and mesofauna assessments reinforced our observed soil fauna responses to reclamation practices. Thus, we encourage multitaxon soil monitoring during land reclamation. Where landfill restoration was carried out to a poor standard, results suggest that soil mesofauna are better indicators of soil status than earthworms. For future restoration schemes, best-practice methods are recommended to improve poor-quality reclaimed soil materials to facilitate rapid soil fauna recolonisation and soil structural development.

Waste disposal and housing price: new evidence from the landfill clean-up program in Hong Kong

Accurately measuring the costs and social benefits of environmental programs may have significant public sector policy implications. When considering environmental programs, governments may choose to conduct landfill clean-ups to improve urban living environments and health. However, these programs may generate substantial costs, and it is not clear whether their social benefits can recover these costs. Since the 1990s, the Hong Kong government has restored 13 closed landfills. This study seeks to quantify the short-term social benefits of this landfill clean-up program by measuring its impact on the housing market. Using the difference-in-differences method, we find that housing prices near landfill sites increase about 2.2%, on average, within two years after landfill restoration. However, housing prices show no further change after the restored landfill sites are redeveloped into urban parks and other facilities. We argue that removal of the stigma effect is likely the main channel for housing price hikes. Through a back-of-the-envelope estimation, we find that the social benefits from housing value appreciation can sufficiently recover the program costs.

Heavy metals contamination within restored landfill site in Poland

This study was aimed at determination of the influence of an old municipal landfill site on the pollution of soil and groundwater by heavy metals. The impact assessment was conducted on the bases of piezometric recording, laboratory tests and site investigation, which gave information on the contamination level and direction of the pollutant migration. Based on the groundwater monitoring results, maps of heavy metal distribution and migration paths within the landfill surroundings were provided. The monitoring data show improvement in water quality in almost every piezometer after only a few years, since the soil–water protection system, including a vertical barrier and dewatering systems, has been installed at the site. This indicates that the reduction in heavy metals within the vicinity of the landfill is continuously progressing in time. On the basis of the obtained results, the magnitude of variability in pollutant migration and changes in concentration, as well as the efficiency of the vertical barrier, were assessed.

Understanding synergies and trade-offs between water and energy production at landfill sites

Landfills provide the most commonly used waste disposal solution. They are designed to reduce the risk of environmental or public health hazards due to waste disposal, and are used for waste management purposes in many places around the world. Depending on the design of the site and recovery methods, landfill sites can work as a potential reserve of energy and water for society. Landfill biogas is a source of renewable energy, and surface water can be collected in a retention pond. Although researchers broadly agree on the importance of incorporating the concept of the energy and water nexus into policy strategies and decision-making, the lack of studies focused on how governance methods that incorporate energy-water linkages at landfill sites can improve the provision of these two essential services has hindered progress in this direction. This study analyzes the links between water-energy nexus at a restored landfill site in Taipei City, Taiwan. The study tracks leachate and methane production at the site over the time periods when the landfill was actively receiving waste and after its closure and since its restoration. The results of model simulation of leachate yield and methane collection under different conditions show that energy and water production changed considerably during the time span under consideration. We identified an increasing trend of water and energy production in the landfill operation phase and a decreasing trend of water and energy production in the landfill restoration phase. In addition, we also identify a synergy between energy generation and water volume during the operation phase, and show that no trade-offs between energy generation and water volume were observed during any of the phases studied. These observations imply that greater water volumes will always lead to greater energy production, which can help inform future landfill design and governance practices.

Effect of soil conditions and landscape factors on macro-snail communities in newly created grasslands of restored landfill sites in the UK

Though restored landfill sites provide habitat for a number of taxa, their potential for land snail remains unexplored. In this study, large-sized land snails (> 5 mm) were surveyed using transect sampling on nine restored landfill sites and nine corresponding nature sites in the East Midlands region of the UK during 2008. The effect of restoration was investigated by examining land snail species composition, richness, and diversity (Shannon Weiner index) in relation to habitat and landscape structure. Thirteen macro-snail species were found in total and rarefied species richness and diversity on restored landfill sites was not found to be statistically different to that of reference sites. One third of the snail species, comprising 30% of total abundance, found in the restored landfill sites were non-native species introduced to the UK. Soil electrical conductivity was the strongest predictor for richness and diversity of land snails. Road density was found to have a positive influence on snail species diversity. Given the high percentage of introduced species detected further research is needed in terms of the management implications of restored landfill sites and the dynamics of native versus non-native species.

Vegetation cover and grasslands in the vicinity accelerate development of carabid beetle assemblages on restored landfill sites

There is an increasing evidence that rare and scarce carabid species of conservation importance are frequent in brownfield sites such as restored landfills. However, this potential has largely been unexplored. The present study was undertaken to examine carabid species composition, richness and abundance in relation to habitat quality and landscape structure on landfill sites in comparison with paired reference sites of existing wildlife value. Sampling was conducted by collecting carabids in ten pitfall traps set along two 100 m transects on each of nine restored landfill sites and their paired reference sites in the East Midlands region of the UK. A total of 1014 individuals representing 37 carabid species were found during April–September of 2007 and 2008. On the surveyed landfill sites, generalist species were common, while no nationally rare or scarce species were found. Neither species richness nor diversity of carabid species was found to be different from that of the reference sites. Seeding durin...

Evaluating Habitat Manipulations and Rodenticides to Protect Seedlings from Rodent Damage at Restored Landfills in New York

AbstractSolid waste landfills have become rather commonplace in urbanized and industrialized regions of the world. If designed, managed, and restored properly, they can be converted to useful land uses. However, restoration of woody vegetation can be difficult when animal damage occurs. Numerous species of voles occur throughout the northern hemisphere and several may become serious pests of restoration plantings at high population density, increasing the expense and difficulty of establishing targeted plant communities. We anticipated that meadow voles (Microtus pennsylvanicus) were responsible for causing the majority of damage to seedlings planted on restored landfill sites in Brooklyn, New York. We evaluated the ability of two habitat manipulations (e.g. mowing, pea gravel barrier) and rodenticides to protect seedlings. We documented substantial damage and deaths of seedlings caused by rodents in the study plots with losses (damaged or dead seedlings combined) ranging from 40 to 73%. These losses occurred regardless of seedling species. Because of the preponderance of voles (71% of all first‐time captures), we suspect that voles are the main species causing seedling damage. Substantial losses of seedlings occurred across treatments, although there were fewest losses with a pea gravel barrier treatment. While the pea gravel treatment reduced seedling losses about 55% compared to control plots, it is clear that additional research is needed to identify more efficient ways to reduce seedling losses to rodents in restoration plantings.

Plant community composition and attributes reveal conservation implications for newly created grassland on capped landfill sites

Biodiversity conservation through restoring degraded habitats or creating new habitats is advocated in the UK Biodiversity Action Plan. Restored grasslands on capped landfill sites are semi-natural habitats that could potentially support a wide range of plant communities. However, it is unknown whether these re-created habitats represent a significant resource in terms of biodiversity conservation. The UK National Vegetation Classification (NVC) was used to study these communities on nine restored capped landfill sites together with paired reference sites in the East Midlands region of the UK during 2007. Plant species data were collected by random quadrats along two 100m transects from each site. The effects of restoration were investigated by examining plant attributes and Ellenberg indicators on restored landfill sites in comparison to paired reference sites. A total of 170 plant species were found from both sets of sites. There were no significant differences for most of the plant attributes between restored landfill sites and reference sites, though reference sites had significantly higher mean frequencies of native plants, nationally decreasing species and perennial species. In total 26 broad NVC community types were identified of which more than 70% fell within mesotrophic grassland (MG). The diversity of NVC communities confirms that underlying environmental factors such as soil fertility are important, dictating the type of plant communities that exist. It is recommended that management of these capped landfill sites should be targeted towards specific NVC community types to meet conservation targets.

Grassland Restoration on Landfill Sites in the East Midlands,United Kingdom: An Evaluation of Floral Resources and Pollinating Insects

AbstractPollinators are declining in Europe due to intensification of agriculture, habitat loss and fragmentation. Restored landfill sites are a significant potential reserve of semi‐natural habitat, so their conservation value for supporting populations of pollinating insects was here examined by assessing whether the plant and pollinator assemblages of restored landfill sites are comparable to reference sites of existing wildlife value. Floral characteristics of the vegetation and the species richness and abundance of flower‐visiting insect assemblages were compared between nine pairs of restored landfill sites and reference sites in the East Midlands of theUnited Kingdom, using standardized methods over two field seasons. No differences were found between the restored landfill and reference sites in terms of species richness or abundance of plants in flower and both types of site had similar assemblages of pollinators. However, plant and insect assemblages differed across the season, with species richness and abundance being lower for the restored landfill sites in the spring and higher in the autumn compared to the reference sites. The results indicate that in this region, landfill sites are being restored to a state comparable to that of the reference sites with regards to their provision of floral resources and the associated insect pollinator assemblages. Since there are currently 2,200 working landfill sites in England and Wales, covering 28,000 ha, and closing at a rate of 100 per year, this is potentially a significant reserve of land that could be restored.

Influence of habitat quality, landscape structure and food resources on breeding skylark (Alauda arvensis) territory distribution on restored landfill sites

The skylark (Alauda arvensis) lost half its number after it underwent a decade of rapid decline from the mid-1970s onwards and since then has continued to decline albeit at a reduced rate. Its listing as a UK Red-List and Biodiversity Action Plan (BAP) Priority Species has helped focus conservation action in an attempt to halt the decline and stabilise populations by restoring degraded habitats or by creating new habitats. Newly created grassland on restored landfill sites are semi-natural habitats that could potentially contribute to this process, however the extent to which these areas support breeding populations is unknown. Territory densities of breeding skylarks were studied on nine restored landfill sites in the East Midlands region of the UK during May to July 2008. The effects of restoration were investigated by examining how habitat quality, landscape factors and food resources determined territory densities. Mean vegetation height and size of sites were found to be significant predictors of the number of breeding skylarks at the local scale, whilst percentage of woodland, grassland and open habitat in the surrounding landscape had an influence at a larger scale. Mean larval and adult invertebrate abundance and species richness in skylark territories in restored landfill sites were found to be similar to that of reference sites of recognised nature conservation value. Restoration of landfill sites could be targeted toward species-specific goals since such sites could play a role in meeting targets for habitat and/or species restoration targets in the UK BAP.

The conservation value of restored landfill sites in the East Midlands, UK for supporting bird communities

There has been a rapid decline of grassland bird species in the UK over the last four decades. In order to stem declines in biodiversity such as this, mitigation in the form of newly created habitat and restoration of degraded habitats is advocated in the UK biodiversity action plan. One potential restored habitat that could support a number of bird species is re-created grassland on restored landfill sites. However, this potential largely remains unexplored. In this study, birds were counted using point sampling on nine restored landfill sites in the East Midlands region of the UK during 2007 and 2008. The effects of restoration were investigated by examining bird species composition, richness, and abundance in relation to habitat and landscape structure on the landfill sites in comparison to paired reference sites of existing wildlife value. Twelve bird species were found in total and species richness and abundance on restored landfill sites was found to be higher than that of reference sites. Restored landfill sites support both common grassland bird species and also UK Red List bird species such as skylark Alauda arvensis, grey partridge Perdix perdix, lapwing Vanellus vanellus, tree sparrow, Passer montanus, and starling Sturnus vulgaris. Size of the site, percentage of bare soil and amount of adjacent hedgerow were found to be the most influential habitat quality factors for the distribution of most bird species. Presence of open habitat and crop land in the surrounding landscape were also found to have an effect on bird species composition. Management of restored landfill sites should be targeted towards UK Red List bird species since such sites could potentially play a significant role in biodiversity action planning.

Energy production from biomass (part 1): overview of biomass

The use of renewable energy sources is becoming increasingly necessary, if we are to achieve the changes required to address the impacts of global warming. Biomass is the most common form of renewable energy, widely used in the third world but until recently, less so in the Western world. Latterly much attention has been focused on identifying suitable biomass species, which can provide high-energy outputs, to replace conventional fossil fuel energy sources. The type of biomass required is largely determined by the energy conversion process and the form in which the energy is required. In the first of three papers, the background to biomass production (in a European climate) and plant properties is examined. In the second paper, energy conversion technologies are reviewed, with emphasis on the production of a gaseous fuel to supplement the gas derived from the landfilling of organic wastes (landfill gas) and used in gas engines to generate electricity. The potential of a restored landfill site to act as a biomass source, providing fuel to supplement landfill gas-fuelled power stations, is examined, together with a comparison of the economics of power production from purpose-grown biomass versus waste-biomass. The third paper considers particular gasification technologies and their potential for biomass gasification.

Effects of rooting and tree growth of selected woodland species on cap integrity in a mineral capped landfill site.

The above and below ground growth of three tree species (Alnus glutinosa, Pinus nigra var. maritima and Acer pseudoplatanus) was studied on a containment landfill site at Waterford, Hertfordshire, UK. Tree root architecture was studied using soil inspection pits excavated next to 12 trees of each species and mapped in detail. Tree height was related to soil thickness over the compacted mineral cap. No roots entered the cap where soil thickness was 1.3 m, but a few roots, especially of alder, were observed within it when the soil cover was 1.0 m or less. Micromorphological analysis of undisturbed samples of the mineral cap suggested that roots exploited weaknesses in the cap rather than actively causing penetration into it. Alder roots were more tolerant of anaerobic conditions within the cap than the other species examined. The results confirm that mineral caps should be covered by 1.5 m of soil or soil-forming material if tree establishment is intended over a restored landfill site, unless protected by other parts of a composite capping system.

Colonisation, survival and spread of earthworms on a partially restored landfill site

Colonisation, survival and spread of earthworms on a partially restored landfill site

EXAMINATION OF TREE AND ROOT PERFORMANCE ON CLOSED LANDFILLS IN MERSEYSIDE

Summary A study of the above ground and below ground growth of alder, willow and poplar on four poorly restored landfill sites in Merseyside has been carried out, in conjunction with measurements of physical site characteristics. Soil gas analysis identified the incidence of high methane (CH4) and carbon dioxide (CO2) and low oxygen (O2) concentrations in the root zone at some sites. Statistical analysis revealed that tree roots were inhibited by high soil bulk density. Height growth was also inhibited by soil compaction, and high soil CO2 and low oxygen concentrations. The results demonstrate that satisfactory woodland can only be achieved if adequate physical soil conditions are obtained. However, the study also shows that useful woodlands may develop without a detailed and expensive restoration prescription.

Colonization of a restored landfill site by invertebrates, with particular reference to the Coleoptera

Colonization of a restored landfill site by invertebrates, with particular reference to the Coleoptera

Soil atmosphere concentration profiles and methane emission rates in the restoration covers above landfill sites: Equipment and preliminary results

In an investigation into the microbial oxidation of methane in soils, a simple and robust sampling device for the collection of small samples of soil atmosphere was used. The method has the potential for determining small-scale variations in depth profiles of gases, without the potential problems of sample migration during collection. Measurements of methane concentration profiles at a number of points along a transect in a restored landfill site in Essex correlated well with the measured emission of landfill gas from the surface of the soil. Emissions were only detected where methane concentrations reached the soil surface.

Soil Atmosphere Concentration Profiles and Methane Emission Rates in the Restoration Covers Above Landfill Sites: Equipment and Preliminary Results

In an investigation into the microbial oxidation of methane in soils, a simple and robust sampling device for the collection of small samples of soil atmosphere was used. The method has the potential for determining small-scale variations in depth profiles of gases, without the potential problems of sample migration during collection. Measurements of methane concentration profiles at a number of points along a transect in a restored landfill site in Essex correlated well with the measured emission of landfill gas from the surface of the soil. Emissions were only detected where methane concentrations reached the soil surface.