Land Reuse Research Articles

Effects of thermal desorption temperature up to 500°C on the thermophysical properties and fertility of soil in organic-contaminated sites

High-temperature thermal desorption is effective for remediating organic-contaminated sites, but its damage to soil functions and high energy consumption raise concerns. In this work, the variation of fertility indicators of two soils with thermal treatment temperature was investigated experimentally. To overcome the difficulties in measuring soil thermophysical properties under sealing and high-temperature conditions, two apparatus matching with the Hot Disk device were established and by which massive data were measured. The results show that, as temperature rises up to 500°C, the combustion and decomposition of organic components and soil minerals gradually enhance, leading to a decrease in most fertility indicators, but an increase in grain size and pH. Available phosphorus and exchangeable potassium decrease with temperature rise first, but increase over 400°C. Soil thermal conductivity and specific heat are positively correlated with temperature and water content. Water diffusion will intensify over 40∼60°C, leading to an intense increase in soil thermal conductivity. The results are expected to provide data basis and theoretical guidance for the comprehensive consideration of remediation effects, land reuse, and energy consumption in practical applications of thermal desorption remediation.

Pro- and Contra-Coalition: Governing the Rise and Fall of Creative Industrial Parks in China

A great number of creative industrial parks (CIPs) have emerged in the past two decades in China as a critical and popular approach to the adaptive reuse of abandoned industrial land in cities. However, a few vibrant CIPs have been closed in the past few years, and the sites are set to be demolished and redeveloped in a property-led manner, suggesting the fragility of CIPs as a land reuse approach. This article aims to elaborate on the institutional rationale behind such a phenomenon. Cases in Shanghai and Guangzhou are examined and presented. The key arguments include: (a) in the industrial land redevelopment process, public and private actors flexibly establish pro-coalitions and contra-coalitions to foster and close CIPs, with strategies to overcome institutional obstacles and to implement land redevelopment-pursued regulatory plans, respectively; (b) key actors forming the two coalitions overlap, such as the local government and the state-owned enterprise land occupiers, and their positions shift subject to specific circumstances; and (c) the finding of the two coalitions echoes the existing argument that there are forces beyond the growth machine driving China’s urban development and provides further insight into the explicit framework of the dual forces underneath.

Investigation of ground subsidence response to an unconventional longwall panel layout

Ground subsidence caused by extraction of longwall panels has always been a great concern all over the world. Conventional longwall mining system (CLMS) gives rise to wavy subsidence causing great damage to surface structures. A coal mine in Shanxi, China, utilizes a split-level longwall layout (SLL) for a sub-horizontal No. 8 coal seam to improve the cavability of mudstone interlayer and top coal. This layout, however, also produced unexpectedly favorable surface subsidence. Subsidence of No. 6 and No. 8 longwall panels was monitored while mining was conducted. Field instrumentation and numerical simulation were carried out. It is demonstrated that an asymmetric subsidence profile with stepped subsidence and cracks occurred on the tailgate side but relatively mild and smooth deformation on the other. Due to elimination of conventional parallelepiped gate pillar, No. 6 and No. 8 gobs were connected. Extraction of two SLL panels acted as one supercritical panel. The maximum possible subsidence was reached which lowers the likelihood of potential future secondary subsidence as underground gob fractures and voids have closed. Therefore, SLL is more favorable for post-mining land reuse as gobs are more consolidated underground.

CURRENT STATUS AND EFFICIENCY OF ABANDONED LANDS RE-DEVELOPMENT IN RIVER BASINS OF SOUTH-WESTERN TRANSBAIKALIA

Complex ecological and economic studies of post-agrarian landscapes in the middle reaches of the Selenga, Chikoy and Temnik rivers were carried out within the boundaries of the Selenga administrative region of the Republic of Buryatia (RB). A map of abandoned agricultural lands has been compiled. A brief description of agroclimatic conditions of the study area is given; the structure of agricultural land, the yield of grain and forage crops, the dynamics of livestock and the load of livestock on pastures and hayfields are analyzed. The reasons for the arable land abandonment are formulated. It was revealed that pastures and hayfields are not excluded from the agricultural use. This is due to an increase in the livestock numbers in households, which are the main agricultural producers in the RB, as well as a shortage of natural forage lands. The species composition and the state of shelterbelt forests are described as an integral part of the ecotopes of post-agrarian landscapes. The main taxonomic indicators of trees are given. The study of shelterbelt forests is topical due to the need for their inventory, lack of maintenance, and the adoption of Federal Laws on protective afforestation and land reclamation. A brief agrochemical description of the state of soils in key areas is given. To assess the effectiveness of arable land reuse, a net operating income (NOI) or rental income was calculated for each grain and grainfodder crop grown in the region under study. It was revealed that oats and spring wheat are the most profitable. Recommendations were formulated for the redevelopment of post-agricultural landscapes, optimization of protective afforestation, and reconstruction of shelterbelt forests

Predicting regional sustainable development to enhance decision-making in brownfield redevelopment using machine learning algorithms

Brownfield redevelopment and land sustainable management have many interconnected aspects, which could be evaluated by regional development. Most contaminated sites in Taiwan often lack comprehensive consideration during remediation for land reuse planning; therefore, they are operated independently from regional development. Regional development is a dynamic process; however, there is a research gap in understanding how regional development can serve as an incentive for brownfield redevelopment. This study established a model for assessing regional sustainability using machine learning (ML-RSD), that model used principal component analysis (PCA) and support vector machine (SVM) to predict the comprehensive evaluation rating of regional development at the township level and to explore the trends of regional governance sustainability. The results of ML-RSD that are compared to commonly used methods (driver-pressure-state-impact-response and entropy weight method) were consistent. Indicators such as the protection of vulnerable groups (SDG1), food security (SDG2), good health and well-being (SDG3), inclusive and equitable quality education (SDG4), environmental protection (SDG6), accessible and reliable energy (SDG7), and sustainable economic growth (SDG8) were identified as the main factors affecting regional development. Additionally, the model achieved an accuracy value exceeding 80%. Additionally, the results showed that there was no significant correlation between the delisted site (completed remediation) and regional development in southern Taiwan. The model underscored the overall lower comprehensive sustainable values for regions affected by inadequate land rehabilitation governance (SDG15). The results present that brownfield redevelopment strategies should enhance their effectiveness in land adaptation and integrating brownfield redevelopment with regional sustainable development is essential for it to become a win–win solution.

A true green cover for industrial waste landfills

Greenhouse gas (GHG) emissions in the United States totaled 5,981 million metric tons of carbon dioxide equivalent (MMT CO2eq) in 2020. Of that, GHG emissions by the pulp and paper sector amounted to 35 MMT CO2eq direct emissions and those by industrial waste landfills summed to 7.4 MMT CO2eq direct emissions. Loss of GHG sinks due to change in land use further contributes to the net GHG emissions. Industrial waste landfills are typically required to comply with certain federal and state regulations, including meeting requirements for final cover systems. Conventional final cover systems have included use of soil covers and/or soil-geosynthetic composite covers. An engineered turf cover provides for an excellent “green” alternative final cover system for industrial waste landfills. This paper discusses various sustainability aspects pertaining to use of an engineered turf final cover, including: (i) significantly low carbon footprint associated with the construction of an engineered turf alternative final cover when compared to closure using a traditional or prescriptive cover system; (ii) saving valuable soil and land resources; (iii) saving water resources by reduction in its use during and after construction; (iv) reducing impacts associated with borrow areas; and (v) reducing overall carbon footprint. Further, when using an engineered turf cover, opportunities exist for beneficial reuse of land, including development of solar energy. A brief discussion on the potential for development of solar energy is included.

Application of Genetic Algorithm in Optimization Simulation of Industrial Waste Land Reuse

In order to better understand the application of optimization simulation for industrial waste land reuse, the author proposes an application study based on nonlinear genetic algorithm in the optimization simulation of industrial waste land reuse. The author takes the landscape renovation and reuse of industrial waste sites as the research object, and through research on the current situation of landscape renovation and reuse of industrial waste sites both domestically and internationally, as well as on-site inspections, attempts to use landscape design techniques to deal with this once glorious but destructive industrial landscape that has already declined. Secondly, a genetic algorithm for enhancing the timeliness of industrial waste land reuse is proposed, which is based on random walks, combine users' long-term and short-term preferences to calculate the most suitable Top-N industrial waste land reuse optimization model for the current period. Finally, the two algorithms proposed by the author were experimentally validated on the dataset. In the CiteU Like dataset, the best performance was achieved at a=0.4, while in the JD dataset, the best performance was achieved at a=0.6. When k=6, the hit rate significantly decreases by about 50%. The URT-R genetic algorithm exhibits a high recommendation hit rate in recommendations targeting timeliness. The author analyzed the different characteristics of industrial waste reuse in scenic areas and optimized their essence and transformation methods, further improving the transformation and renewal methods of industrial waste land in the process of urban development in China. I hope to provide useful references for future research on related topics and practices.

An improved dynamic game analysis of farmers, enterprises and rural collective economic organizations based on idle land reuse policy

Land use is a crucial symbol of sustainable development. Rural homestead idleness is problem that is caused by market failure and related to the national economy and people's livelihood. (1) Background: Developing countries should use idle land to develop their economies. The government has introduced various land policies for the reuse of idle residential land to improve the land utilization rate. (2) Methods: This paper investigates players' behavior in reusing rural homesteads based on an improved dynamic game model. An improved tripartite evolutionary game model is developed by introducing principal-agent theory, which is the major contributor to behavioral investigation. MATLAB2022a is used to simulate the analysis to propose countermeasures and suggestions for optimizing homestead reuse. (3) Results: In this paper, it was found that disputes among participants about the sharing of reuse costs and the distribution of potential benefits constituted a potent system of explanatory coordinates that effectively revealed the hidden logic of homestead reuse. The government can strengthen incentives by providing dynamic subsidies linked with individual behavior. (4) Conclusions: Regardless of the initial probability, players will jointly reuse homesteads in the end. Local governments and rural collective economic organizations play an important role in reusing homesteads, so the carrot-and-stick approach supervised by local government is the key to maintaining the stability of cooperation. Moreover, under the concept of sustainable development, governments of all countries actively release the policy of reusing idle land to promote the utilization of resources.

Waste Frontiers/War Enclosures: Decolonial Geosocial Analysis of Contaminated Military Land Conversions

Military-industrial practices have left widespread contamination affecting land, water, air, and human and nonhuman bodies. This article uses decolonial analysis to examine the racial-colonial foundations that underlie contemporary efforts to reuse former U.S. military land for development projects. Interrelating scholarship on security and development with that of militarization and political ecology, I use “geosocial spectacle” to probe the material and pedagogical governance, frontier logics, and colonial aesthetics that emerge through land remediation and redevelopment. Featuring two military sites within U.S. base closure and realignment—the U.S. Front Range area of Colorado and former U.S. unincorporated territory of the Panama Canal Zone—the article delineates and expounds on two types of U.S. military land conversions: brownfields and biodiversity recreation. The article interrelates the conversion of contaminated land in both cases as waste frontier that facilitates ongoing cycles of land repossession as a form of dispossession and containment or denial of war. The article concludes by advocating for decolonial studies of the global color line entrenched by the U.S. Pentagon’s ongoing climate colonialism, to subvert the compartmentalized harms of war and capitalist extraction, and to galvanize explicitly anticolonial, antiracist land reuse and governance.

Monitoring Net Land Take in a Metropolitan Region—Portugal

This study seeks to contribute to the definition of a “no net land take” policy by 2050 for Portugal’s second-largest metropolitan region (AMP, Porto Metropolitan Area) while sensitising those involved in regional and local planning to the European target. Based on an assessment of land use changes in AMP and its municipalities during 2007–2018, soil sealing levels in 2018 and population evolution, the study quantifies the processes that may impart achievement of the 2050 objective and identifies the regional drivers of net land take, to support the definition of both interventions to decrease land take and soil sealing and related targets. The main contribution of the research is the exploration of new indicators in terms of soil sealing and population data to identify the potential for implementing interventions proposed by the EU Soil Strategy that do not jeopardise the maintenance of biodiversity in urban areas. The land take rate in the AMP was the highest among mainland Portugal regions. Its main drivers were the development of transport networks, industrial and commercial units and dispersed housing. The reuse and re-naturalisation of artificial land have seen little use in the region. Accordingly, the daily net land taken in the AMP (0.59 ha/day) still needs to decrease until 2050. While artificial land increased across the AMP, most of its municipalities lost population. To reverse this trend, the AMP should implement tighter control mechanisms that ensure that infrastructure and housing needs are fully met through the reuse of urban areas that are already sealed. However, given that the share of impermeable soil in most urban areas is already significantly high, there will have to be a careful choice of locations where intensifying land use will cause less environmental damage. It is concluded that the degree of soil sealing within urban areas is fundamental for deciding on the interventions to be carried out to reduce net land take and for defining a policy towards meeting the 2050 target.

Optimizing the development of contaminated land in China: Exploring machine-learning to identify risk markers

Often available for use, previously developed land, which includes residential and commercial/industrial areas, presents a significant challenge due to the risk to human health. China's 2018 release of health risk assessment standards for land reuse aimed to bridge this gap in soil quality standards. Despite this, the absence of representative indicators strains risk managers economically and operationally. We improved China's land redevelopment approach by leveraging a dataset of 297,275 soil samples from 352 contaminated sites, employing machine learning. Our method incorporating soil quality standards from seven countries to discern patterns for establishing a cost-effective evaluative framework. Our research findings demonstrated that detection costs could be curtailed by 60% while maintaining consistency with international soil standards (prediction accuracy = 90–98%). Our findings deepen insights into soil pollution, proposing a more efficient risk assessment system for land redevelopment, addressing the current dearth of expertise in evaluating land development in China.

A framework for identifying the distribution of revitalization potential of idle rural residential land under rural revitalization

Idle rural residential land (IRRL) serves as a crucial resource for rural land utilization. Evaluating its potential for revitalization forms the foundational research in rural land consolidation. In the context of rural revitalization, quantitatively determining the potential to revitalize IRRL is a fundamental scientific investigation, requiring focus within the field of rural land sustainability research. In our study, we have developed a framework for identifying IRRL revitalization potential under rural revitalization, combining with the village development environment and self-characteristics of IRRL, and have proposed a classification method of IRRL revitalization types. Our results found a spatial mismatch between the IRRL revitalization potential and the external conditions of consolidation potential release. Compared with the IRRL consolidation potential based on spatial characteristics, the vitality of rural revitalization in Pinggu is small, which is manifested as low vitality of rural revitalization and surplus revitalization potential. Under rural revitalization, the IRRL revitalization potential in Pinggu is low. In the central agricultural and eastern semi-mountainous regions, IRRL plays a pivotal role in land reutilization within the context of rural revitalization. Moderate revitalization is the dominant revitalization type. The revitalization of IRRL in the central agricultural and eastern semi-mountainous regions plays a pivotal role in the reuse of residential land within rural revitalization. The prominent revitalization type is characterized as moderate revitalization. Considering the diversity of rural revitalization in Pinggu, the revitalization of IRRL should prioritize meeting a range of land usage needs within the rural revitalization context. Furthermore, it should capitalize on surplus potential through strategies like spatial transfer or retaining idle IRRL. Our research aims to foster a fresh perspective on the potential for revitalizing IRRL within the rural revitalization framework, emphasizing rural regional systems. This, in turn, can facilitate the harmonization of IRRL utilization with rural development, offering theoretical underpinning for human-land coordination and sustainable rural development in developing nations.

Distribution, sources, and health risk assessment of VOCs/SVOCs in soils obtained from petrochemical-contaminated sites in Guangzhou, a subtropical coastal megacity in southern China

Investigation and analysis of the soil contamination characteristics of legacy petrochemical sites is the basis for safe land reuse. Volatile/semivolatile organic compounds (VOCs/SVOCs) are a group of mutagenic, carcinogenic, and teratogenic substances that can induce leukemia, brain tumors, asthma, and a variety of other cancers through oral ingestion, dermal exposure, and/or inhalation. This study was designed to explore the horizontal and vertical distribution characteristics, sources, and health risks of VOCs/SVOCs in different operational areas of an abandoned petrochemical enterprise site in Guangzhou City. The survey assessed the presence and amounts of 12 VOCs/SVOCs across 522 soil samples. Measurements were conducted using a combination of purge and trap-gas chromatography and mass spectrometry (P&T-GC-MS). The investigation revealed that the total content of the 12 compounds was 69798.7 μg kg−1, with an average value of 5816.6 μg kg−1. The highest benzene content was 10900 μg kg−1, with an average value of 462.5 μg kg−1, and the maximum value exceeded this average by 2.7-fold. According to the horizontal distribution, VOCs/SVOCs were mainly concentrated in the oil delivery console, storage tank area, oil refining area, and fire pumping stations. Depending on the vertical distribution, pollutants were generally distributed in the plain fill layer, with a downward trend in the muddy silt and silt layers. The source apportionment of VOCs/SVOCs was analyzed and discussed with correlation analysis and a positive matrix factorization (PMF) model in this study. The source analysis results showed that a mixture of petroleum, solvent, and coal sources, solvent sources, and traffic sources were the main sources of VOCs/SVOCs, and their contribution rates to VOCs/SVOCs were 17.7%, 70.0% and 12.3%, respectively. The health risk assessment showed that 8 carcinogenic VOCs/SVOCs carry potential carcinogenic risks for children and adults. This study can provide data support and a judgment basis for the redevelopment of contaminated sites, determination of pollution responsibility and effective management of soil pollution.

The potential to produce safe textiles in a phytoattenuation strategy: The fate of Cd and Pb during industrial treatments on contaminated hemp fibers

Industrial hemp (Cannabis sativa L.) is getting increased attention as a sustainable alternative to synthetic fibers and cotton in the textile industry, as well as a candidate for phytoremediation, as it has been shown to tolerate stress from heavy metal-contaminated soil and experiences no or only little decrease in yields. With the EU Soil Strategy of 2030 promoting land reuse, hemp could be a perfect candidate for fiber production for textiles while growing on heavy metal contaminated land and restoring the soil. This strategy, combining safe biomass production and land valorization, is called phytoattenuation. In this study, Cd and Pb-contaminated hemp fibers underwent demineralization and bleaching treatments, commonly used in the textile industry. Total and extractable Cd and Pb concentrations were analyzed and assessed against legal safety thresholds and toxicity thresholds used in the textile industry to evaluate the safety of these fibers for textile production. Total and extractable Cd and Pb concentrations were below the total (40 mg/kg Cd and 90 mg/kg Pb) and extractable (0.1 mg/kg Cd and 1.0 mg/kg Pb) safety limits in the treated fibers after the combined demineralization and bleaching treatments. To understand in which parts of the fiber Cd and Pb are concentrated, fibers were analyzed for their cellulose, hemicellulose, and lignin content after each treatment. Extractives such as pectin were removed during demineralization and bleaching removed part of the lignin and hemicellulose. This corresponded respectively to a decrease in Cd and Pb, suggesting that Cd is rather bound to pectin in the primary wall, while Pb could be bounded to lignin and hemicellulose in the secondary wall of the fiber. However, the fate of the elements in the fiber remains complex. Overall, the results are promising for safe textile production from hemp fibers grown on Cd and Pb-contaminated soil.

Revitalization of idle rural residential land: Coordinating the potential supply for land consolidation with the demand for rural revitalization

The consolidation and reuse of idle rural residential land (IRRL) is a key component when studying rural sustainable land use. Scientifically understanding the relationship between the consolidation of IRRL and rural revitalization and exploring ways to revitalize IRRL through rural revitalization are key scientific issues that urgently need to be solved for rural land sustainability. By applying an integrated framework, the potential supply for consolidation and the utilization demand of IRRL under rural revitalization are synthetically identified, and the supply-demand relationship is further explored. Finally, diversified revitalization for IRRL based on the coordination of supply and demand is proposed. The results show that the dominant sources of the consolidation potential for IRRL are agricultural land supply, ecological improvement and industrial land supply. The dominant demands for IRRL involve industrial development, residence function and ecological protection. There is an obvious mismatch between the consolidation potential supply and the utilization demand of IRRL, and the lack of consolidation potential supply is the main source of this mismatch. Under the trade-off between consolidation potential supply and rural revitalization demand, industrial development and ecological improvement are the dominant utilization directions of IRRL in Pinggu, and fewer villages are being used for residential improvement. The direct consolidation of village functions, the transformation into a land index for spatial transfer, and maintaining the land as idle are the primary revitalization methods for IRRL. The study aims to realize the potential value of IRRL and to deeply explore the human-land adaptation relationship under rural revitalization to enrich the research system of sustainable land use and provide a reference for rural land rights reform in developing countries.

PET addition delays the composting mature process and promotes microbiota associated with plastic degradation in plastisphere

Microplastics (MPs) enter forest and turf-grass and non-edible crops through sludge land reuse, thereby posing a major risk to human health and environmental security. MPs contamination can influence various biochemical processes by shifting microbial communities. However, the MPs effects in high-temperature sludge composting, as well as the microbiota associated with plastic degradation remain largely unexplored. Herein, we determined the effects of polyethylene terephthalate (PET) MPs on sludge-straw composting and microbial communities in 6 Biolan 220L composters for 50 days, using next generation sequencing technology. Our results showed that the humic acid to fulvic acid ratio (HA/FA) of PET treatment was lower (0.78) comparing to control, indicating that PET addition delayed the humification of composting. The Shannon indexes of the plastisphere were higher than surrounding compost and CK at the ripening phase (day 50), suggesting that MPs had a greater microbial enrichment. PET exposure altered the community composition, reduced the microbial network complexity, and decrease the relative abundance of thermophilic genus. Notably, several plastic degradation microbiota genera, including Brevibacterium, Halomonas and Aspergillus, were enriched in plastisphere, especially during the high thermophilic stage of sludge composting. There was a significant increase in the relative abundance of plastic degradation bacteria and fungi in plastispheres 0.38 ± 0.3% and 15 ± 6%, respectively, compared to those in the surrounding compost material. In summary, these findings indicate that plastisphere can accumulate potential microbiota associated with plastic degradation in high-temperature composting, which is beneficial to the development of future aerobic fermentation technology for MPs degradation.

An Interactive Decision Support System for Land Reuse Tasks.

Experts face the task of deciding where and how land reuse-transforming previously used areas into landscape and utility areas-can be performed. This decision is based on which area should be used, which restrictions exist, and which conditions have to be fulfilled for reusing this area. Information about the restrictions and the conditions is available as mostly textual, nonspatial data associated to areas overlapping the target areas. Due to the large amount of possible combinations of restrictions and conditions overlapping (partially) the target area, this decision process becomes quite tedious and cumbersome. Moreover, it proves to be useful to identify similar regions that have reached different stages of development within the dataset which in turn allows determining common tasks for these regions. We support the experts in accomplishing these tasks by providing aggregated representations as well as multiple coordinated views together with category filters and selection mechanisms implemented in an interactive decision support system. Textual information is linked to these visualizations enabling the experts to justify their decisions. Evaluating our approach using a standard SUS questionnaire suggests that especially the experts were very satisfied with the interactive decision support system.

Sustainable decision-making for contaminated site risk management: A decision tree model using machine learning algorithms

The presence of contaminated land is an inevitable legacy of industrial activity, and the management decisions governing reclamation of this land are key in minimizing environmental risk and allowing safe and effective land reuse. In this context, to predict the optimal remediation options for future decision-making processes in sustainable site management, thus enhancing information communication between stakeholders, 17 decision sensitivity parameters are analyzed in this study and their influence on the management patterns of contaminated sites identified with three decision tree (DT) algorithms including C4.5 (successor of Iterative Dichotomiser 3/ID 3), CHAID (Chi-squared Automatic Interaction Detection), and CART (Classification and Regression Trees), which is the first attempt to use artificial intelligence technology to predict strategy-based decision-making for contaminated site management. Based on four performance metrics (accuracy, precision, recall ratio and F1 score), CART-based DT model shows the highest prediction accuracy at an average value of 78.57%, which indicates a relatively credible decision simulation to assist in more efficient contaminated site management. With regard to specific factors and influence mechanisms on contaminated site management, the results demonstrate 7 recognition rules corresponding to 6 driving factors which have the greatest influence on the decision-making process. Long-term monitoring time, the type of land reuse and ex-situ performance are the most important factors in determining field implementation of cleanup activities. The built decision tree model and induced decision rules, once well-trained, can be relied on for a sustainable site management strategy as data become available at a new site.

Evaluation of Land Use Adaptation by Sequential Extraction of Soil Trace Elements at an Abandoned Gold and Copper Refinery Site in Northern Taiwan

This study site is located at an abandoned factory of mining, smelting, and refining of gold and copper in north Taiwan for more than one hundred years. The present study used soil background investigation out of the site and the sequential extraction procedures for arsenic and copper to assess the reutilization potential of brownfields at the site. The upper limit of background concentration out of the site was 300 mg/kg for arsenic and 700 mg/kg for copper. The soil arsenic within the site was mainly in the immobile fraction, such as forms fixed by layer silicates, that were very low risk for environmental releases. The soil copper in the abandoned sedimentation basin, gold refinery, and copper refinery was in the mobile fractions such as acid extractable, reducible, and oxidizable forms with higher release risk; therefore, except merely those three zones in the entire site with higher risk for environmental releases of copper, the release risks of trace elements are quite low in the rest of the areas, and land reuse without contact with soil or plant non-edible plants is possible. Therefore, in response to public demand for opening part of the site to promote local tourism development, appropriate control and isolation measures can be implemented to prevent the toxic elements from affecting human health through soil ingestion, skin contact, and other exposure pathways. In terms of pollution control, reducing dust inhalation is also an option to efficiently reduce health risks to an acceptable level and achieve the goal of sustainable land use at the contaminated site.

Strata and surface influence range of deep coal mining for mine land reuse

Determining the strata and surface movement of deep mining can provide a scientific basis for wellbore protection and mine land utilization. In this paper, numerical simulation methods were employed to investigate the stratum and surface movement boundary curves of deep caving and backfilling mining. The findings can be concluded in three aspects. First, the stratum and surface movement boundaries of deep caving and backfilling mining were all curved and conformed to an exponential function, but the influence range of strata and surface movement of deep different mining methods were different. Second, the backfilling rate of deep backfilling mining had an impact on movement boundary boundaries of strata and surface. With the backfilling rate decreasing, the influence range of strata and surface movement boundary were increased. Last, the research results were applied to a case to confirm the new approach of determining the influence range of strata and surface movement of deep mining. The example application shows that it not only can ensure the safe production of the wellbore, but also can enhance the reuse area of the mine field.