Risk grade assessment of sudden water pollution based on analytic hierarchy process and fuzzy comprehensive evaluation

Variability of the trophic state in a coastal reef system associated with submarine groundwater discharge in the Mexican Caribbean

Submarine groundwater discharges (SGD) have been associated with important sources of nutrients between the land and oceans that can generate eutrophication conditions. This study aims to analyze the behavior of nitrogen and phosphorus using the mixing curve method, to examine the variation of the trophic state using the Karydis Index, and to evaluate the δ15N in benthic organisms to trace the origin of nitrogen in neap tide (November) and spring tide (January) in the Manatí Cenote, and Nohoch-Teek reef lagoon in the Mexican Caribbean. Nitrogen and phosphate enrichment was in the Manatí Cenote during neap and spring tides. This enrichment was particularly noticeable in the reef lagoon during low tides in the areas influenced by SGD. In the Cenote, differences in the nitrate trophic state were observed, indicating an eu-mesotrophic condition during neap tide and a mesotrophic condition during spring tide. However, no significant differences were observed for ammonium (oligo-mesotrophic), nitrites, or phosphate compounds (oligotrophic). The trophic state reef lagoon exhibited a similar pattern but with different spatial variations. In both systems, phosphorus was a limiting nutrient, while δ15N suggested anthropogenic nitrogen uptake by several benthic organisms.

A management framework for sudden water pollution: A systematic review output

Numerous sudden water pollution (SWP) incidents have occurred frequently in recent years, constituting a potential risk to human, socio-economic, and ecological health. This paper systematically reviews the current literature, with the view to establishing a management framework for SWP incidents. Only 39 of the 327 downloaded articles were selected, and the ROSES protocol was utilized in this review. The results indicated industries, mining sites, and sewage treatment plants as key SWP contributors through accidental leakages, traffic accidents, illegal discharge, natural disasters, and terrorist attacks. These processes also presented five consequences, including the contamination of drinking water sources, disruption of drinking water supply, ecological damage, loss of human life, and agricultural water pollution. Meanwhile, five mitigation strategies included reservoir operation, real-time monitoring, early warning, and chemical and biological treatments. Although an advancement in mitigation strategies against SWP was observed in this review, previous studies reported only a few prevention strategies. Considering that this review provided an SWP-based management framework and a hydrodynamic model selection guideline, which provide a foundation for implementing proactive measures against the SWP. These guidelines and the SWP-based management framework require practical field trials for future studies. PRACTITIONER POINTS: Sudden water pollution increases with industrial growth but decrease with awareness. Human and ecosystem health and social economy are the endpoint receptacles. Mitigation strategies include reservoir dispatch, early warning, and treatments. DPSIR model forms the basis for proving proactive measures against sudden pollution. This review provides a guideline for the selection hydrodynamic models application.

Spatio-temporal evolution and the driving factors of municipal solid waste in Chinese different geographical regions between 2002 and 2020

Urbanization and economic development have contributed to the rapid and massive generation of municipal solid waste (MSW) and significant changes in spatial patterns, which are becoming a serious pollution problem. Previously, macroscopic studies on the driving factors of MSW have been widely conducted at the national level, but the exploration of the driving factors in different geographical regions on a regional scale has not received much attention in the previous literature. This study is based on China, spatial patterns were analyzed using spatial autocorrelation and movement of center of gravity, and time series clustering was used to explore temporal trends. Subsequently, Geodector was adopted to quantify the relationship between MSW generation and driving factors. The results of the study are as follows: 1) By analyzing the spatial pattern of MSW, this study found that MSW showed a spatial pattern of high in the southeast and low in the northwest during 2002-2020, and its separating line was the same as the Hu-line; the average center of gravity of MSW generation in the past 20 years was always located in Henan Province and shifted southward by 339.7 km. 2) The local spatial autocorrelation analysis results showed that the Low-Low clusters moved from southeast to northwest from 2002 to 2020, increasing to 20 cities. High-High clusters mainly appeared in the East Coast and South Coast regions, increasing from 8 to 17 cities in the last 20 years. 3) The analysis of driving factors by Geodetector revealed that Urbanization is the most critical dimension factor influencing MSW generation, with the strongest impact on the East Coast region. The next dimension is Economy, which has the most significant impact on MSW generation in the North West region. Energy is the third dimension that influences MSW generation, with the greatest impact on the North Coast region. The results of this study reveal trends in the spatial and temporal distribution of MSW in different geographic regions of China over the past 20 years and the impact of their driving factors, which can help the Chinese government take action to control MSW in a site-specific manner.

Implementation of pollution source assessment and treatment strategy for plateau railway construction in China: an AHP-cloud model approach

During the construction process of railways in the plateau region, various types of pollution sources can have serious or even irreversible impacts on the plateau ecology. To address pollution source treatment during the construction process, protect the ecological environment along the railway, and maintain the ecological balance, we collected geological and environmental data and analyzed the influencing factors of pollution sources. Taking sewage as the main research subject, we propose a new method based on the Analytic Hierarchy Process (AHP)-cloud model to classify the pollution source treatment level, establish an index system, and select the ecological environment level, sewage rate, and pollutant characteristics as the three main influencing factors. Finally, we divide the pollution source treatment level into I, II, and III, corresponding to V1 = {I-level} = {high impact}, V2 = {II-level} = {moderate impact}, and V3 = {III-level} = {low impact}. Based on the comprehensive factor weight analysis and the field engineering conditions of the studied railway in the western plateau of China, we classify the pollution source treatment level of six tunnels and propose treatment suggestions for each level. To advance the efficient implementation of environmental protection during the construction of the plateau railway, we propose three policy recommendations that can positively contribute to environmental protection and green development. This work provides theoretical and technical guidance for the treatment of pollution sources in the construction of the plateau railway, which also serves as a significant reference for other similar projects.

System comprehensive risk assessment of urban rainstorm-induced flood-water pollution disasters

The urban rainstorm-induced flood-water pollution disaster is a kind of systematic risk, which may induce secondary disasters that can lead to more serious damage, so this paper first adopts the fuzzy comprehensive evaluation method to determine the flood risk by combining with the submergence depth derived from the risk field and other factors data, and then the grid environmental risk evaluation method, which is improved by increasing the induced possibility based on Bayesian theory, is used to evaluate the flood-induced water pollution risk, and the system comprehensive risk of rainstorm-induced flood-water pollution disasters is finally obtained by constructing risk level matrix, which can well depict the coupling superposition effect. Shenzhen City is selected as the study area, and the results showed that the area with high-risk of both flood and water pollution only accounts for about 0.14% of the total area, mainly distributed in the eastern junction of Longgang district and Pingshan district, where the rainstorms occur frequently and the enterprise risk sources are dense. The system comprehensive risk is mostly very low-low and very high-low, accounting for more than 76% of the total area. It is always necessary to pay attention not only to the areas with high risk level of both disasters, but also to the areas with high risk level of one disaster. The method proposed in this study can not only quantitatively reveal the formation of the induced risk, but also provide reference for early warning.

A safety assessment model of filling mining based on comprehensive weighting-set pair analysis

Filling mining is the main mining method in coal mine, and its safety is the pillar of the overall safety of the mine. Filling mining can effectively protect the surface environment, better solve the problem of ground pressure, and maximize the recovery of underground resources. Therefore, this method has an irreplaceable role in deep mining of coal mines and is highly valued by the mining industry all around the world. In order to evaluate the implementation effect of filling mining, a comprehensive weighting-set pair analysis safety evaluation model is established. This model optimizes the subjectivity of analytic hierarchy process (AHP) and the objectivity of Entropy Weight Method (EWM) in traditional methods. Besides, we add experts' weight to Entropy Weight Method. The combination of the two methods makes the index weight more reasonable and effective, and can more fully reflect the difference and correlation of index. Firstly, the accident causation analysis and taxonomy (ACAT) is used to find out the accident causation factors of filling mining, and then, the AHP and EWM are used to determine the weight of each evaluation index from different perspectives. Then, the evaluation group is established to score the importance of each expert, so as to reduce the subjectivity of expert scoring. Finally, according to the principle of set pair analysis, the safety evaluation model of filling mining is applied to Yuxing Coal Mine in Inner Mongolia. The evaluation result shows that the safety grade of this mine is grade 1 "safety." This paper provides a new way and direction for the comprehensive evaluation of similar mining methods, the establishment of index system, the acquisition of index weights, and the evaluation of safety level, which has promotion and application value.

Selection of plastic solid waste treatment technology based on cumulative prospect theory and fuzzy DEMATEL

Under the global implementation of a low-carbon economy, the treatment of municipal plastic solid waste (PSW) has become an important task to be solved urgently. In the actual decision-making process of PSW treatment, the evaluation information is usually fuzzy, and the decision-makers (DMs) are bounded rational. For selecting the most appropriate PSW treatment technology, we propose a multi-criteria decision-making (MCDM) method based on cumulative prospect theory and fuzzy decision-making trail and evaluation laboratory (DEMATEL). Firstly, we construct the criteria system of PSW treatment that consists of 9 sub-criteria from the perspectives of environment, economy, society, and technology. Then, considering the interdependences and interactions between these evaluation criteria and allowing multiple stakeholders to participate in decision-making, we propose a fuzzy DEMATEL method to deal with the fuzziness of evaluation in the decision-making process and determine the weights of the evaluation criteria. Subsequently, taking into account the different opinions of different stakeholders and psychological factors such as risk preference and loss aversion of stakeholders, we aggregate the evaluation information of different stakeholders and develop the PSW treatment alternatives to rank the orders by using the proposed multi-actor cumulative prospect theory (CPT) method. We study seven alternative processes for PSW treatment by the developed model, including landfill, recycling, pyrolysis, incineration, and the combination of landfilling and recycling, landfill and incineration, and recycling and pyrolysis. According to the ranking results, we find the combination of recycling and incineration is the best treatment alternative. We take the seven PSW treatment technologies in Shanghai as the case study to verify the effectiveness and feasibility of the proposed method. Through the sensitivity analysis and comparison analysis with fuzzy similarity to ideal solution (FTOPSIS) method and an acronym in Portuguese of the interactive and multi-criteria decision-making (TODIM) method, we illustrate the effectiveness and superiority of the proposed method. This research provides significant references for the PSW treatment technology selection problems under uncertain environments and extends the methods in the decision-making field.

Water pollution incidents and their influencing factors in China during the past 20 years

There is an urgent need to explore the current situation of China's water pollution incidents for policymaking, accident prevention, and risk mitigation. This study analyzed 1528 water pollution incidents in China from 2001 to 2020 and explored the spatiotemporal characteristics and causes of incidents and consequent damage. The frequency of water pollution accidents increased in 2004, peaked in 2006, and decreased thereafter with a significant decline in 2016. Due to the developed river networks, high population densities, and increasing environmental awareness, pollution incidents were mostly concentrated in China's relatively industrially developed eastern coastal regions. Illegal emission is the major cause, accounting for 51% of all incidents, but with pipeline construction gradually approaching a peak, pipeline leakage poses a noteworthy risk in the future. Although the severity of accidents has reduced recently, it is still necessary to strengthen the risk prevention strategies for general and major accidents. Furthermore, three key factors, including economic development, regulations and legal system, and public participation in pollution supervision and control, which affect the trends and characteristics of water pollution incidents in China, were discussed. This paper offers valuable insights and suggestions that may have useful implications for policymaking and the prevention of water pollution.

Spatial-temporal distribution and evolutionary characteristics of water environment sudden pollution incidents in China from 2006 to 2018

Sudden water pollution incidents (SWPI) are random and harmful, which is a problem that cannot be ignored in ecological environment governance and economic development. Identifying spatial-temporal distribution characteristics of SWPI is essential for the disaster prevention and the early warning of water environment. The Kernel Density (DE) and spatial mean center of SWPI transfer curve were used to explore the characteristics with the dataset of 1174 cases from 2006 to 2018 in China. Results showed that: (1) From the time point of view, there was an overall upward trend in the overall number of SWPI. (2) At a regional scale, Eastern China, Southwest China, and Southern China underwent a high frequency with 69.93% of SWPI. The Fujian, Guangdong and Chongqing provinces were specified as the top 3 provinces with incident frequencies. The Yangtze River Basin and the Pearl River Basin were two regions where water pollution incidents occur more often, more than 50% of incidents among basins in China every year. (3) In general, SWPI presents a northeast-southwest distribution pattern and center of SWPI moves in the direction of west by south. (4) More than half of the incidents (57.24% of the total) were induced by illegal pollutant discharge and production safety accidents.

Simulating the impact of piers on hydrodynamics and pollutant transport: A case study in the Middle Yangtze River

It is known that channel engineering, including the construction of piers, will change the river hydrodynamic characteristics, which is a significant factor affecting the transport process of pollutants. With this regard, this study uses the well-validated and tested hydrodynamic module and transport module of MIKE 21 to simulate the hydrodynamics and water quality under various pier densities in the Wuhan reach. Hydrodynamic changes around the piers show spatial differences, which are similar under different discharges. The range and amplitude of hydrodynamic spatial variations increase with the increase in pier density. However, there is a critical value of 1.25 to 2.5 units/km. When the pier density is less than this critical value, this type of cumulative effect is the most significant. Additionally, greater changes can be found in chemical oxygen demand concentrations, which also show spatial and temporal variations. The area with high chemical oxygen demand concentration upstream and downstream from the engineering area exhibits the distribution characteristics of “decrease in the downstream area and increase in the upstream area” and “increase in downstream the area and decrease in the upstream area” respectively. In the reach section of the engineering area, the area with high chemical oxygen demand concentration increases in the front area near the piers and decreases near the shoreline. Furthermore, the concentration shows attenuation actions with a longer residence time owing to the buffering effect of pier groups. These results have significant implications on shoreline planning and utilization. Moreover, they provide scientific guidelines for water management.

A multi-stage fuzzy decision-making framework to evaluate the appropriate wastewater treatment system: a case study

Selection of appropriate treatment processes for wastewater treatment (WWT) plants at the design stage involves a careful examination of different economic, environmental, and social parameters. Designers and decision-makers seek a compromise among such conflicting elements, which can be facilitated by decision support tools that are adapted for the ambiguity of individual opinions and decision parameters. This study aims to improve the qualification and efficiency of decision-making in WWT processes. A multi-stage framework is proposed to help select investments, technology, appropriate technology-specific system, and companies that apply such systems. The framework combines the Analytic Hierarchy Process (AHP), Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE), cash flow analysis, and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) within fuzzy logic. The main contribution is the description and formation of an integrated framework to guide businesses and researchers for the evaluation of several WWT decision processes. To the best of the authors' knowledge, no study in the literature fuses multiple stages of this WWT process with the proposed approaches.

A Critical Review of Methods for Analyzing Freshwater Eutrophication

Water eutrophication is a global environmental problem that poses serious threats to aquatic ecosystems and human health. The evaluation of eutrophication provides a theoretical basis and technical guidance for the management and rehabilitation of water ecosystems. In the last four decades, dozens of evaluation methods have been applied to freshwater eutrophication, but there is a clear need to optimize and standardize the most suitable methods. We have addressed this gap by presenting a systematic review of methodologies. Due to the diversity and complexity of water bodies, no single evaluation method was identified that would adequately represent eutrophication under all scenarios. We demonstrate that lakes can best be assessed using the trophic level index (TLI) method, reservoirs and wetlands the trophic state index (TSI) and fuzzy comprehensive evaluation (FCE) method, respectively, and rivers the FCE method or back propagation (BP) neural network methods. More recently applied methodologies including spectral imaging and 3-D mapping of water quality using underwater gliders allow greater resolution and can be effective in managing waterbodies to avoid future eutrophication. The aim of this review is to guide future studies on the most appropriate methods available for assessing and reporting water eutrophication.