Characterizing the implications of waste dumping surrounding the Yangtze River economic belt in China

An ensemble machine learning model to uncover potential sites of hazardous waste illegal dumping based on limited supervision experience

With the soaring generation of hazardous waste (HW) during industrialization and urbanization, HW illegal dumping continues to be an intractable global issue. Particularly in developing regions with lax regulations, it has become a major source of soil and groundwater contamination. One dominant challenge for HW illegal dumping supervision is the invisibility of dumping sites, which makes HW illegal dumping difficult to be found, thereby causing a long-term adverse impact on the environment. How to utilize the limited historic supervision records to screen the potential dumping sites in the whole region is a key challenge to be addressed. In this study, a novel machine learning model based on the positive-unlabeled (PU) learning algorithm was proposed to resolve this problem through the ensemble method which could iteratively mine the features of limited historic cases. Validation of the random forest-based PU model showed that the predicted top 30% of high-risk areas could cover 68.1% of newly reported cases in the studied region, indicating the reliability of the model prediction. This novel framework will also be promising in other environmental management scenarios to deal with numerous unknown samples based on limited prior experience.

Factors influencing illegal dumping of hazardous waste in China

In recent years, illegal dumping of hazardous waste (IDHW) in China has become a recurring problem. Effective identification and exploration of the factors influencing illegal dumping are crucial for incident prevention and hazardous waste management, but its analysis has rarely been reported. Thus, this study focused on 568 cases of IDHW officially reported by the government. Through regular expressions, the categories of dumped wastes and the provinces where the incidents occurred were extracted. Furthermore, a comprehensive set of influencing factors was constructed by text mining for the case content and by the integration from the existing literature. On this basis, the unstructured and structured data were integrated using a Boolean dataset to respectively explore the association rules of influencing factors for the overall IDHW and for major waste categories, in conjunction with the extracted province information. Subsequently, a Bayesian network was constructed by utilizing the results of association rules mining and the key factors were identified through corresponding analysis. The findings of this study reveal a close connection between various influencing factors, with distinct key factors identified for different categories of hazardous waste. Among them, law-enforcement emerges as a crucial factor in most IDHW cases, while the factor of public monitoring for metallic hazardous waste and the factor of government supervision for distillation residue waste and other waste play a key role in their respective cases of illegal dumping. These findings offer a fresh research perspective for investigating the factors influencing IDHW and present helpful insights for developing effective strategies to prevent and control such incidents.

Acceptable risk assessment and management of environmental pollution emergency events base on distance model

Existing environmental management regulations and assessment methods can help understand and relieve pollution problems greatly affecting the natural world. However, what is lacking is awareness and targeted recommendations for environmental pollution emergency events (EPEEs). Here we analyzed a total of 2164 EPEEs in China from 2000 to 2021 in terms of annual variations, spatial distributions, phases of regional development, and pollution sources. The findings showed that regional economies can have significant impacts on the occurrence of EPEEs. Regarding the four causes of pollution, the contribution from industrial sources was above 80 %, especially water pollution events, for which it accounted for 84 %. The probability of pollution events specifically relates to regional GDP and it was highest in those provinces with the highest GDP rankings, albeit there were marked differences in the industrial structure. In order to better manage EPEEs, an Environment-Emergency Distance Model (EEDM) is proposed. This model uses the Multidimensional psychological distance to quantitatively evaluate the acceptable public risk level after the occurrence of EPEEs. This method provides a basis for pollution prevention and remediation by visualizing the risk acceptable for the public and provides guidance for sustainable environmental development.

Geopolymer-Based Artificial Aggregates: A Review on Methods of Producing, Properties, and Improving Techniques

The depletion of aggregate-related natural resources is the primary concern of all researchers globally. Recent studies emphasize the significance of recycling and reusing various types of natural or by-product material waste from industry as a result of the building industry's rising demand for aggregate as the primary component in concrete production. It has been demonstrated that the geopolymer system has exceptional features, such as high strength, superior durability, and greater resistance to fire exposure, making it a viable alternative to ordinary Portland Cement (OPC) concrete. This study will examine the present method utilized to generate artificial aggregate-based geopolymers, including their physical and mechanical properties, as well as their characterization. The production process of geopolymer derived from synthetic aggregates will be highlighted. In conjunction with the bonding of aggregates and the cement matrix, the interfacial transition zone (ITZ) is highlighted in this work as an additional important property to be researched in the future. It will be discussed how to improve the properties of geopolymers based on artificial aggregates. It has been demonstrated that cold bonding provides superior qualities for artificial aggregate while conserving energy during production. The creation of ITZ has a significant impact on the bonding strength between artificial aggregates and the cement matrix. Additionally, improvement strategies demonstrate viable methods for enhancing the quality of manufactured aggregates. In addition, other recommendations are discussed in this study for future work.

An overview of the environmental pollution and health effects associated with waste landfilling and open dumping

Landfilling is one of the most common waste management methods employed in all countries alike, irrespective of their developmental status. The most commonly used types of landfills are (a) municipal solid waste landfill, (b) industrial waste landfill, and (c) hazardous waste landfill. There is, also, an emerging landfill type called "green waste landfill" that is, occasionally, being used. Most landfills, including those discussed in this review article, are controlled and engineered establishments, wherein the waste ought to abide with certain regulations regarding their quality and quantity. However, illegal and uncontrolled "landfills" (mostly known as open dumpsites) are, unfortunately, prevalent in many developing countries. Due to the widespread use of landfilling, even as of today, it is imperative to examine any environmental- and/or health-related issues that have emerged. The present study seeks to determine the environmental pollution and health effects associated with waste landfilling by adopting a desk review design. It is revealed that landfilling is associated with various environmental pollution problems, namely, (a) underground water pollution due to the leaching of organic, inorganic, and various other substances of concern (SoC) contained in the waste, (b) air pollution due to suspension of particles, (c) odor pollution from the deposition of municipal solid waste (MSW), and (d) even marine pollution from any potential run-offs. Furthermore, health impacts may occur through the pollution of the underground water and the emissions of gases, leading to carcinogenic and non-carcinogenic effects of the exposed population living in their vicinity.

An implementation framework of blockchain-based hazardous waste transfer management system

The rapid increase in volume and types of hazardous waste (HW) due to China's continuous economic growth makes it significant to conduct HW safety management. However, due to the information asymmetry between the regulators and regulated institutions, problems such as illegal dumping and statistical fraud are common in hazardous waste transfer (HWT) activities. Moreover, there is a severe problem of information isolated island among waste production, transportation, and treatment companies in the HW market. Promoting the information monitoring and tracking of the whole process of HWT is the main challenge for HW management. Blockchain provides an ideal solution to overcome the above challenges. This study developed a framework for the blockchain-based HWT management system, which could support government regulators to obtain relevant information in HWT and improve the efficiency of HWT. The HWT management system was introduced in detail from different perspectives, including infrastructure, blockchain service, functions, and users, emphasizing six information management functions. Finally, the positive impact and various challenges encountered in implementing blockchain in HWT management were discussed. This study applies blockchain to the research field of HWT management, which expands the application of blockchain in the field of solid waste management with great theoretical and practical significance.

Plastic Pollution, Waste Management Issues, and Circular Economy Opportunities in Rural Communities

Rural areas are exposed to severe environmental pollution issues fed by industrial and agricultural activities combined with poor waste and sanitation management practices, struggling to achieve the United Nations’ Sustainable Development Goals (SDGs) in line with Agenda 2030. Rural communities are examined through a “dual approach” as both contributors and receivers of plastic pollution leakage into the natural environment (through the air–water–soil–biota nexus). Despite the emerging trend of plastic pollution research, in this paper, we identify few studies investigating rural communities. Therefore, proxy analysis of peer-reviewed literature is required to outline the significant gaps related to plastic pollution and plastic waste management issues in rural regions. This work focuses on key stages such as (i) plastic pollution effects on rural communities, (ii) plastic pollution generated by rural communities, (iii) the development of a rural waste management sector in low- and middle-income countries in line with the SDGs, and (iv) circular economy opportunities to reduce plastic pollution in rural areas. We conclude that rural communities must be involved in both future plastic pollution and circular economy research to help decision makers reduce environmental and public health threats, and to catalyze circular initiatives in rural areas around the world, including less developed communities.

Status quo of illegal dumping research: Way forward

Due to the rapid social and economic development, the past decades have witnessed the improvement of human being's quality of life and the speedy development of the construction industry. Meanwhile, the illegal dumping of solid waste has presented a significant issue. By using the method of systematic review, this study critically examined the literature related to illegal dumping that were published since 1990, and analyzed the current status and future trends of related research. Results show that the current studies on illegal dumping mainly focus on four perspectives: environmental science and toxicology, economics, management, and the use of emerging technologies. This critical review revealed that although the issue of illegal dumping has been widely recognized in recent years, some questions remain unanswered. Therefore, a future research agenda is proposed. These include: (1) Identifying the migration of pollutants in the food chain during the illegal dumping; (2) Implementing targeted treatment of illegal dumping pollutants; (3) Improving the stakeholder decision analysis model; (4) Expanding the scope of research on stakeholders of illegal dumping; (5) Formulating an unified evaluation standard for the related costs of illegal dumping; (6) Strengthening the evaluation of the interaction effects of influencing factors; (7) Comparing the effects of different types of factors; (8) the exploration of other influencing factors; (9) Analyzing illegal dumping by combining big data with the amount of solid waste; (10) Combining with monitoring to analyze the illegal dumping of household waste.

Three-stage model based evaluation of local residents' acceptance towards waste-to-energy incineration project under construction: A Chinese perspective

Incineration is an efficient and economical means of solid waste disposal. And local residents' acceptance has to be acquired for the smooth going of waste-to-energy incineration project (WTEIP). From a Chinese perspective, this paper finds what influence local residents' acceptance towards WTEIP under construction, based on which we rank WTEIPs and figure out the project with the least local residents' acceptance. To achieve this, a three-stage model is developed. Stage 1 involves identifying the criteria based on the expert judgement for local residents' acceptance towards WTEIP under construction. Stage 2 involves the criteria weights determination employing Best Worst-Decision Making Trial and Evaluation Laboratory (BWD). BWD incorporates Best Worst Method and Decision Making Trial and Evaluation Laboratory which is intended to take the interrelationships among the criteria into account. Stage 3 involves project ranking according to the criteria weights determined by BWD. Sensitivity analysis is conducted to check the effectiveness and robustness of the three-stage model. Results show that perceived risk-free is the most influential criterion of local residents' acceptance towards WTEIP under construction and the three-stage model is reliable and robust. The study is helpful to enhance local residents' acceptance towards WTEIP under construction and provide important reference for decision-makers and policymakers in waste management.

Riverine transport and water-sediment exchange of polycyclic aromatic hydrocarbons (PAHs) along the middle-lower Yangtze River, China

We examined the riverine transport of polycyclic aromatic hydrocarbons (PAHs) based on their spatial-temporal distributions in water and sediments from the mainstream along the middle and lower Yangtze River. According to the fugacity fraction (ff) estimation, sediments performed as a secondary emission source of two-, three-, and four-ringed PAHs and as a sink for five- and six-ringed congeners, leading to higher ecological and human health risks especially towards the lower reaches. The higher PAH levels observed in the more developed delta and megacities were highly linked to economic parameters. This was further supported by the source apportionment performed using the principal component analysis-multiple linear regression (PCA-MLR) model, which showed major contributions of coal and coke combustions along with vehicle emissions. The spatial-temporal distribution revealed that water runoff was the major contribution to PAHs transport along the middle-lower Yangtze River, whereas a sharp decrease in sediment discharge due to the dam impoundment along the upper reaches would lead to an increase in the catchment retention effect of PAHs. Hence, the biogeochemical processes of PAHs and their impacts on the fragile ecosystems as a consequence of the further modification of the sedimentary system in rivers need to be fully explored.

Short-chain chlorinated paraffins in soils indicate landfills as local sources in the Tibetan Plateau

Background contamination levels of contemporary persistent organic pollutants (POPs) may be elevated due to local discharges, and hence it is of high importance to assess and monitor them in alpine and Polar Regions. This study investigated the role of waste disposal in the Tibetan plateau as the local source of short-chain chlorinated paraffins (SCCPs). SCCPs were determined in soils from the urban landfill and rural dumpsites, with a concentration range of 56.8-1348 ng/g dw. The gradient descent of SCCP levels from Lhasa landfill to the surrounding soils with increasing distances suggested a significant SCCP release from waste disposal. The transport pattern was well fitted by the Boltzmann equation after normalization in terms of soil organic carbon contents. Compared to the landfill cells closed in early years, the recently closed cells contained higher concentrations but lower proportions of the short-chain congener groups, likely reflecting the SCCP use history in Tibet. In open-burning dumpsites, higher SCCP levels and dominance of lighter congener groups indicates that such crude waste treatment process might cause an extra release of volatile SCCPs. This study elucidates local SCCP inputs to the background environment, and demonstrates that both urbanization and badly-managed landfill have been contributing to the presence of contemporary POPs in the Tibetan Plateau.

Spatial variation in biodiversity loss across China under multiple environmental stressors

Biodiversity is essential for the maintenance of ecosystem health and delivery of the Sustainable Development Goals. However, the drivers of biodiversity loss and the spatial variation in their impacts are poorly understood. Here, we explore the spatial-temporal distributions of threatened and declining ("biodiversity-loss") species and find that these species are affected by multiple stressors, with climate and human activities being the fundamental shaping forces. There has been large spatial variation in the distribution of threatened species over China's provinces, with the biodiversity of Gansu, Guangdong, Hainan, and Shaanxi provinces severely reduced. With increasing urbanization and industrialization, the expansion of construction and worsening pollution has led to habitat retreat or degradation, and high proportions of amphibians, mammals, and reptiles are threatened. Because distributions of species and stressors vary widely across different climate zones and geographical areas, specific policies and measures are needed for preventing biodiversity loss in different regions.

Integrating ecosystem services value and uncertainty into regional ecological risk assessment: A case study of Hubei Province, Central China

In the context of rapid urbanization, ecosystem services (ES) losses pose serious threats to sustainability. How to assess ecological risk based on ES value (ESV) has become an urgent problem for sustainable urbanization. However, existing regional ecological risk assessment frameworks ignore important elements, such as the assessment endpoint and uncertainty, weakening their reliability and practicability. In this study, a regional ecological risk assessment framework integrating ESV and uncertainty was proposed by introducing a classical financial indicator, the Sharpe Ratio. We take Hubei Province, Central China as a case and implemented the spatially explicit risk assessment approach based on the methods of the Markov-logistic-CA model, adjusted-based equivalent factor evaluation model, and geographic information system. The results showed that the distribution of expected ecological returns and corresponding uncertainties at county level had a remarkable spatial heterogeneity, and the assessed ecological risk index in Eastern and Western Hubei was higher than that in Central Hubei, indicating that counties in Central Hubei are the priority areas for ecological risk control. Moreover, the expansion of built-up land had the most significant effect on regional ecological risk. This regional ecological risk framework can well integrate the assessment endpoint and dynamic processes of ecological risk. Our assessment framework has potential practical value for ecological risk control and land use planning on ecosystems.

Canonical Correlation Study on the Relationship between Shipping Development and Water Environment of the Yangtze River

The sustainable development of the Yangtze River will affect the lives of the people who live along it as well as the development of cities beside it. This study investigated the relationship between shipping development and the water environment of the Yangtze River. Canonical correlation analysis is a multivariate statistical method used to study the correlation between two groups of variables; this study employed it to analyze data relevant to shipping and the water environment of the Yangtze River from 2006 to 2016. Furthermore, the Yangtze River Shipping Prosperity Index and Yangtze River mainline freight volume were used to characterize the development of Yangtze River shipping. The water environment of the Yangtze River is characterized by wastewater discharge, ammonia nitrogen concentration, biochemical oxygen demand, the potassium permanganate index, and petroleum pollution. The results showed that a significant correlation exists between Yangtze River shipping and the river’s water environment. Furthermore, mainline freight volume has a significant impact on the quantity of wastewater discharged and petroleum pollution in the water environment.