2023 Vol. 13, No. 5

Display Method:
Overview and consideration of laws and regulations and technical specifications for soil pollution prevention and control at home and abroad
WEI Xiaoshu, BAI Yangwei, WANG Xiaowei, WANG Wensi, YANG Niyun, ZHANG Qiuying
2023, 13(5): 1643-1651. doi: 10.12153/j.issn.1674-991X.20230157
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A sound legal and regulatory system and its supporting technical norms are the basis and guarantee of soil quality protection and pollution prevention. Drawing on advanced soil pollution prevention technologies and management experience has important guiding significance for soil pollution prevention and control work in China. The characteristics of laws, regulations and technical norms of soil pollution prevention and control in developed countries and China were expounded comprehensively and systematically. The relevant foreign advanced experience was summarized. The problems and challenges of soil pollution prevention and control in China were analyzed, and some countermeasures and suggestions for soil pollution prevention and control in China were put forward. Although China had formed a relatively complete legal and regulatory system with soil risk management and control as the core and with the principle of "prevention first and combining with treatment", covering soil pollution prevention, investigation and monitoring, risk assessment and control, remediation and treatment, development and reuse, etc., the legal details at each stage still needed to be improved, and there is a lack of special legislation for different types of contaminated sites. Therefore, the improvement of relevant laws and regulations on soil pollution prevention and control should be speeded up. In addition, some of the current technical standards for soil pollution prevention and control in China were blank or lagging behind, which could no longer meet the practical needs of soil environmental management, and need to be expanded and tightened continuously.

Research progress in advanced oxidation technologies for remediation of polycyclic aromatic hydrocarbons contaminated soils
REN Tianlin, ZHAO Likun, CHEN Chaoqi, MAO Xuhui
2023, 13(5): 1652-1662. doi: 10.12153/j.issn.1674-991X.20230165
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Polycyclic aromatic hydrocarbons (PAHs) are hydrocarbon compounds composed of two or more benzene rings. Their carcinogenic, mutagenic and teratogenic properties have adverse effects on human health and ecological environment. Due to the characteristics of low water solubility, high hydrophobicity and difficult degradation of PAHs, the remediation of PAHs-contaminated soil poses significant challenges. Advanced oxidation technologies have emerged as effective approaches for addressing PAHs contamination in soil. The research progress in the field of advanced oxidation technologies for the remediation of PAHs-contaminated soil was summarized, with a focus on the advantages and disadvantages analysis of ozone oxidation, Fenton oxidation, and persulfate oxidation. Furthermore, the role of surfactants in enhancing the effectiveness of advanced oxidation was explored and the influence of soil physicochemical conditions on the oxidation process was discussed. Potential impacts of the oxidation process on the soil microenvironment were also analyzed. Finally, the research difficulties and future directions of remediation of PAHS-contaminated soil by advanced oxidation were pointed out.

Research progress on polycyclic aromatic hydrocarbons degrading bacteria and their applications
LI Hua, ZHAO Likun, BAO Shiyu, YU Xiaolong, MAO Xuhui, CHEN Chaoqi
2023, 13(5): 1663-1676. doi: 10.12153/j.issn.1674-991X.20230152
Abstract(709) HTML (202) PDF(2141KB)(101)
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Polycyclic aromatic hydrocarbons (PAHs) are a group of pollutants widely distributed in the environment and have ecological and environmental toxicity effects. Therefore, the remediation and restoration of PAHs-contaminated sites have received significant attention. Biodegradation is one of the essential technologies for removing PAHs; however, it still faces limitations such as low degradation efficiency and long degradation periods. The common PAHs-degrading bacteria and their degradation mechanisms were summarized, focusing on discussing the research progress and limitations of applying them to real contaminated sites. The results showed that PAHs-degrading bacteria mainly included genus Acinetobacter, Mycobacterium, and Pseudomonas. White-rot fungi were common fungi that degraded PAHs. Compared to individual strains, bacterial consortia exhibited superior PAH degradation capability. For PAHs such as naphthalene, phenanthrene and pyrene, the degradation process involved ring opening catalyzed by enzymes encoded by PAHs degradation genes (e.g., nah gene cluster), followed by stepwise oxidation, ultimately leading to complete degradation through the salicylic acid or phthalic acid pathway entering the tricarboxylic acid cycle. The degradation of benzo[a]pyrene produced intermediate products, including alcohols, aldehydes, and acids. However, its complete degradation pathway was yet to be identified. Studies on PAHs degradation bacteria were mainly confined to laboratory conditions, and there was a lack of verification in real contaminated soils. In application, the activity of degrading bacteria and the efficiency of PAHs removal were influenced by various environmental factors, including temperature, pH, oxygen levels, and soil organic matter content. In addition, some cases utilized biological stimulation and/or bioaugmentation to significantly improve the bioremediation of PAH-contaminated sites. Nevertheless, the application must overcome multiple limiting factors, including reduced degrading bacteria activity, failed integration with multiple technologies, and high environmental risks and costs. Further researches should include the mechanisms of PAHs biodegradation under conditions with combined pollution and the presence of indigenous microorganisms, the regulation of physiological characteristics of degrading bacteria, and the development of novel materials. Furthermore, promoting the application of PAHs-degrading bacteria in real contaminated sites should be strengthened to achieve efficient, economical, and sustainable control of PAHs contamination

Effect of inoculation of functional bacteria on the remediation of petroleum polluted soil and the microbial community
ZUO Yilin, CHEN Wenjie, SUN Huijie, DING Xiaoyan, ZHAN Yabin, ZHANG Hao, DING Guochun, LI Ji, WEI Yuquan, LIU Rui
2023, 13(5): 1677-1685. doi: 10.12153/j.issn.1674-991X.20230177
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The dibenzothiophene (DBT) degrading bacteria screened and domesticated based on previous culture experiment was inoculated into the petroleum contaminated soil for a 40 day simulated soil remediation experiment. The degradation effect of functional bacteria (Rhodococcus sp. ZYL-1) and the succession of bacterial community in the petroleum contaminated soil was analyzed. The results showed the addition of Rhodococcus sp. ZYL-1 increased significantly the degradation efficiency of DBT compared to control during the incubation at 25 ℃ in the dark chamber (P<0.001). The DBT degradation in the bioaugmentation treatment (BIOEIF) mainly occurred in the first 10 days after soil incubation, in which DBT degradation rate was close to 60% at the end of incubation, higher than that in the control, i.e., natural attenuation treatment (NAT) relying on soil indigenous microorganisms. Compared with the bacterial community composition between BIOEIF treatment and NAT treatment in the soil incubating process, the Shannon diversity index and phylogenetic diversity index of BIOEIF were significantly lower than that in NAT, but the inoculation of Rhodococcus sp. ZYL-1 did not affect significantly the composition of the soil bacterial community. Micromonospora, Bacillus, and unclassified_f_Planococcaceaeis were detected as the dominated taxa in the petroleum contaminated soil, but Rhodococcus which was inoculated did not have an obviously high abundance in soils. Network analysis showed that key functional bacteria for DBT degradation had significantly improved in the contaminated soil in BIOEIF, which might be due to the symbiosis of Shimazuella with indigenous microorganism. In conclusion, the inoculated functional bacteria (Rhodococcus sp. ZYL-1) could obviously improve the biodegradation of DBT in petroleum hydrocarbon contaminated soil based on enhancing the degradation function of indigenous microorganisms.

Research progress on quorum sensing regulation of organic pollutants biodegradation
YU Xiaolong, MAO Xuhui, ZHENG Yan
2023, 13(5): 1686-1693. doi: 10.12153/j.issn.1674-991X.20230151
Abstract(336) HTML (92) PDF(662KB)(52)
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The biodegradation of organic pollutants is influenced by microbial activities, and quorum sensing (QS) is a crucial mechanism that regulates physiological activities. During the biodegradation process of organic pollutants, QS affects the synthesis of key enzymes for degradation, the formation of biofilms, the regulation of microbial community structure, etc. Furthermore, directly adding QS signaling molecules or using bacterial agents that produce such molecules can promote QS regulation, thereby enhancing organic pollutants biodegradation rates. However, environmental factors like pH, temperature, quorum quenching bacteria, nanoparticles, etc., can negatively impact QS activities. Currently, research on QS regulation of organic pollutant biodegradation is still in its early stages. This review summarizes the progress of related research, discusses the mechanisms of QS on the biodegradation of organic pollutants, outlines strategies to enhance QS regulation, identifies the main environmental factors affecting QS activities, and provides prospects for its application.

Research progress of slurry bioreactor bioremediation of refractory organic matter contaminated soil
LI Guowen, ZHAO Chen, CUI Jianglong, LIU Cao, BAI Miaoxin, ZHANG Lieyu
2023, 13(5): 1694-1700. doi: 10.12153/j.issn.1674-991X.20230161
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Slurry bioreactors are widely used in bioremediation of soils polluted by refractory organic matter because of their fast mass transfer, controllable conditions and high remediation efficiency. The main removal mechanisms of solid-liquid mass transfer, gas-liquid mass transfer and biodegradation involved in the bioremediation of refractory organic matter in slurry bioreactor were reviewed, and the importance of three removal mechanisms, namely solid-liquid mass transfer, gas-liquid mass transfer and biodegradation, was summarized. The research progress of bioreactor modeling at home and abroad was summarized, and the basic models of solid-liquid mass transfer, gas-liquid mass transfer and biodegradation processes were formed. The important parameters of the slurry bioreactor were determined, including physical parameters, biological parameters and operating parameters, and the influence mechanism of various parameters and their suitable range were summarized. Finally, the future research directions of slurry bioreactor to remove refractory organic matter were prospected, including mechanism research, microbial agents, and intelligent application equipment.

Study on the collaborative degradation process based on bioaugmentation for the remediation of polycyclic aromatic hydrocarbons in the soil from a coking plant site
ZHAO Likun, BAO Shiyu, GUO Tao, CHENG Yiqing, ZHENG Yan, YU Xiaolong, LIU Yuanwen, YANG Lewei, LIU Peng, MAO Xuhui
2023, 13(5): 1701-1710. doi: 10.12153/j.issn.1674-991X.20230164
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Four remediation processes were designed and experimentally validated by coupling surfactants-washing, biodegradation, and chemical oxidation techniques for polycyclic aromatic hydrocarbons (PAHs) contaminated soil from an abandoned coking plant. The results showed that a single soil-slurry bioreactor degradation process could achieve 58.64% PAHs degradation in 21 days for the actual coking-contaminated soil. The degradation process of surfactants-washing+chemical oxidation+soil-slurry bioreactors could achieve 65.68% degradation in 26 days, but the prepositive chemical oxidation would inhibit the biodegradation effect. The degradation process of dry-sieving+surfactants batch washing+chemical oxidation could achieve an 85.36% degradation effect, which could effectively shorten the degradation time to 13 days, but the residual PAHs in the soil were closely bound with soil particles, and the degradation effect of chemical oxidation was still difficult to meet the degradation efficiency of more than 90%. The collaborative degradation process based on bioaugmentation of wet-sieving+surfactants batch washing+soil-slurry bioreactors+chemical oxidation could achieve a 95.32% degradation effect in 29 days and achieved the target value of soil remediation. The collaborative degradation process based on bioaugmentation integrated the advantages of various remediation technologies and realized the optimization of the combination of remediation technologies, which provided a feasible process path for the remediation of PAHs in contaminated soil of coking industry.

Research on designing an intelligent platform for soil and groundwater remediation based on big data, intelligent control, IoT and cloud computing
SUN Tong, HE Mengxi, HE Li, JIN Tao
2023, 13(5): 1711-1716. doi: 10.12153/j.issn.1674-991X.20230255
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To comply with national requirements of accelerating industrial transformation and upgrading, and promoting green and low-carbon development, and solve the problems of low level of intelligence, low degree of information and communication construction, incoordination between decision-making and construction, low efficiency in contaminated site remediation, an intelligent platform for soil and groundwater remediation was constructed according to the thinking of "existing problems analysis, overall architecture design, and the application of key technologies" and in combination with new information technology (IT) and operational technology (OT). The platform was designed based on big data, intelligent control, Internet of things (IoT) and cloud computing, and made full use of new technologies including big data, IoT, cloud computing and intelligent control to solve the existing engineering problems, and could realize big data acquisition, big data exchange, cloud computing and digital twin simulation. Through multi-level digital transformation, it helped achieve the goal of soil and groundwater remediation in the whole process, and promoted the intelligent and low-carbon development of the industry.

Path planning and transportation task assignment algorithm for multiple unmanned ground vehicles in soil contaminated site
JIN Binghui, SUN Yang, WU Wenjun, ZHAI Mengdi, GAO Qiang, SI Pengbo
2023, 13(5): 1717-1724. doi: 10.12153/j.issn.1674-991X.20230160
Abstract(157) HTML (71) PDF(1753KB)(34)
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In order to improve the intelligent equipment level of bioremediation technology, a heavily polluted coke plant was taken as the research environment, and the double deep Q network (DDQN) and ant colony optimization algorithm (ACO) were used to establish a multiple unmanned ground vehicles (multi-UGV) path planning and task assignment system for the topographical features of the coke plant to achieve safe and accurate transportation of contaminated soil in the soil remediation process and improve the efficiency of contaminated soil transportation. The results showed that the multi-UGV transportation system based on DDQN and ACO had good path planning capability, and the ACO task assignment algorithm based on the actual system time cost could achieve a stable reduction of UGV system time cost under different loading quantities compared with other task assignment strategies obtained based on simple linear distance or based on the greedy algorithm.

Field testing of pilot-scale bioslurry reactor for coking contaminated site: a case study in Anhui Province
LI Fei, DING Haoran, YANG Yuewei, LIU Yuanwen, WANG Heng, ZHANG Yue, LI Shupeng, CHEN Cheng, TIAN Dejin
2023, 13(5): 1725-1731. doi: 10.12153/j.issn.1674-991X.20230145
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Polycyclic aromatic hydrocarbons (PAHs), especially high-molecular-weight PAHs, are the characteristic pollutants in coking contaminated sites, which are documented as highly toxic and recalcitrant to degrade. Due to the high controllability and high efficiency for insoluble organic pollutants, bioslurry reactor technology is a promising engineering process for soil remediation. To explore the variations of microbial communities after inoculation, and optimize the fluctuation range of solid content and the key parameters of microbial reaction, a self-developed 1 m3 slurry reactor tank combined with commercialized PAHs-degrading agent was adopted to conduct a pilot test at a representative contaminated field. The results showed that the microorganisms grew rapidly at the 3rd to 6th week under the stimulation of nutrients, reflected by the obvious proliferation of genus such as Hydrogenophaga, Sphingomonadaceae, and Pseudomonas, which were likely involved in the degradation of PAHs. Meanwhile, the concentrations of representative high molecular weight PAHs, namely benzo[a]anthracene, benzo[b]fluoranthene and benzo[a]pyrene, were reduced from several times the control target of Class 1 of building land in Soil Environmental Quality Risk Control Standard for Soil contamination of Development Land (Trial) (GB 36600-2018) to below the target value. In view of the lack of actual site pilot scale data in China, this study obtained reliable bioslurry reactor operation data and promoted the technology to engineering scale in China.

Analysis of application cases of multi-technology combined treatment for typical coking contaminated site
DING Haoran, WANG Dixiang, CHEN Cheng, YANG Yuewei, WU Teng, WANG Heng, XU Hongwei, YANG Xuezhi, LIU Peng
2023, 13(5): 1732-1739. doi: 10.12153/j.issn.1674-991X.20230144
Abstract(257) HTML (87) PDF(1125KB)(61)
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Typical coking-contaminated sites have obvious composite pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) and heavy metals, and single remediation technology is often difficult to complete the treatment. The application practice of multi-technology combined remediation has been carried out, but the site pollution characteristics and engineering technical problems applicable to the combined application technology are rarely reported. PAHs and heavy metals in the coking-contaminated sites are primarily distributed within the shallow soil, indicating compound pollution. However, there is minimal interaction between these two kinds of pollutants. Therefore, a combined remediation technology with soil leaching as its core is suitable for application due to its advantages of saving restoration cycle and cost. The main technical challenge lies in preventing and controlling secondary pollution. In the future, a synergistic approach combining soil leaching, chemical oxidation, and bioremediation technologies can be developed for environmentally-friendly restoration.

Spatio-temporal evolution and prediction of carbon storage in Chang-Zhu-Tan 3+5 urban agglomeration based on optimization simulation
MI Yi, LI Tao, WU Bo, ZHAO Yanping
2023, 13(5): 1740-1751. doi: 10.12153/j.issn.1674-991X.20221291
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Land use or cover change (LUCC) is an important factor leading to the change of carbon storage in regional ecosystems. Exploring the spatio-temporal evolution law of land use and carbon storage is of great significance to regional land spatial planning and ecological management, as well as to the realization of the strategic goal of "dual carbon". The GeoDetector-PLUS-InVEST model was built to analyze the spatio-temporal evolution characteristics of land use and carbon storage of Chang-Zhu-Tan 3+5 urban agglomeration from 2000 to 2020 based on multi-source data, to predict the changes of land use and carbon storage under different scenarios in 2030, and to analyze the spatial distribution regularity of carbon storage through the spatial autocorrelation model. The results showed that: 1) Kappa coefficient, FoM coefficient and overall accuracy of the optimized simulation model were 0.81%, 1.00% and 0.67%, respectively, higher than those of the non-optimized simulation. 2) From 2000 to 2020, the land use changes in the study areas showed that the areas of cultivated land, forest land, grassland and water decreased, and the areas of construction land and unused land increased. 3) The carbon storage of the three phases in 2000, 2010 and 2020 were 31.262 4×108、31.218 1×108 and 31.089 1×108 t, respectively, during which the carbon storage decreased by 17.328 7×106 t. 4) Compared with 2020, carbon storage under the natural development scenario in 2030 would decrease by 12.148 3×106 t, carbon storage decrease by 11.746 7 ×106 t under the urban development scenario, carbon storage increase by 14.754 0×106 t under the ecological protection scenario. The spatial distribution of carbon storage under the three different scenarios was relatively similar, with the remarkable characteristic of spatial agglomeration, and it was closely related to land use. The research results could provide decision-making reference for the land space planning and formulation of "dual carbon" policy within Chang-Zhu-Tan 3+5 urban agglomeration.

Simulation of land use zoning optimization under multi-objective scenarios based on maximizing carbon storage: taking Qingshui River of Xijiang River in Guangxi as an example
WU Xinyu, QIN Menglin, JIANG Hongbo, ZHAO Yincheng, LUO Dingding, WANG Zhengqiang
2023, 13(5): 1752-1762. doi: 10.12153/j.issn.1674-991X.20221203
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Land use change is an important factor affecting carbon sequestration change, and land use optimization plays an important role in realizing regional carbon balance. Based on the data of land use in 2000, 2010 and 2020, the temporal and spatial development characteristics of land use change and carbon storage in Qingshui River basin in 2060 were predicted by FLUS-InVEST coupling model under different simulation scenarios (baseline scenario, cultivated land protection scenario, water area protection scenario, and high-carbon storage land protection scenario). Aiming at the suitable development direction of high, medium and low carbon storage capacity grade regions, a grey linear programming model based on the maximization of carbon storage was constructed to optimize the quantitative structure of land use and simulate the spatial layout of land use using FLUS model. Fragstats software was used to analyze the morphological pattern of different land use types in the upper, middle and lower reaches of the basin, and analyze their correlation with carbon storage, and corresponding optimization strategies. The results showed that: 1) Under the four simulation scenarios, the carbon storage in the basin would increase steadily in 2060 only under the high-carbon storage land protection scenario, and decrease significantly under the other three scenarios. 2) Based on the optimization scheme, in 2060, the area of forest land, wetland and water area in the basin would increase, the area of construction land would increase steadily, the area of grassland and cultivated land would decrease relatively and the contiguous cultivated land would remain unchanged, and the overall regional carbon storage would increase by 1.32×106 t. 3) The land use pattern of the basin affected the carbon storage, and there was spatial heterogeneity in different segments. On the whole, the patches showed complex and irregular shapes with high degree of aggregation and connectivity, which was conducive to improve the overall carbon storage in the region. Therefore, the optimization proposed in this thesis can better meet the development needs of different regions of the basin while coordinate the overall development at the same time, and eventually increase the carbon storage of the basin and promote the overall benefit optimization.

Study on the mitigation effect of submerged vegetation on greenhouse gases emission from rivers
WEI Yanjie, HU Cheng, LI Yafeng, GENG Jiao, LI Qingqian, SUN Fei, YUAN Peng
2023, 13(5): 1763-1770. doi: 10.12153/j.issn.1674-991X.20221050
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In order to reveal the role of ecological restoration of submerged plants in slowing down the release of greenhouse gases (GHGs) from rivers, the two rivers of Shengjiawan (with submerged plants growing) and Donglonggang (without submerged plants growing) were selected in Jiashan County, Zhejiang Province, and the fluxes of CO2, CH4 and N2O were continuously monitored for 24 hours by the diffusion models. The results showed that except for the CO2 absorption occurrence in Shengjiawan at 16:00, the three gases were supersaturated during the rest of the monitoring time, showing the release of GHGs to the atmosphere. In comparison, within 24 hours, the release of GHGs from Shengjiawan with submerged plants could be reduced by 89%. Based on the correlation analysis between gas release flux and environmental factors, it was found that in Shengjiawan, CO2 emission flux was significantly negatively correlated with water temperature, pH and dissolved oxygen concentration, and positively correlated with redox potential. N2O emission flux was positively correlated with water temperature, pH and dissolved oxygen concentration, and negatively correlated with redox potential. In Donglonggang, there was a significant positive correlation between CO2 release flux and water temperature, a significant positive correlation between CH4 release flux and water temperature and dissolved oxygen concentration, and a significant positive correlation between N2O emission flux and water temperature.

Research on the coupled and coordinated development of economy-environment-carbon emission in forestry resource-based city under the goal of carbon peaking and carbon neutrality: a case study of Yichun City
PENG Haofan, LONG Feng, GE Chazhong, DUAN Xianming, BI Fenfen
2023, 13(5): 1771-1778. doi: 10.12153/j.issn.1674-991X.20230102
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Achieving the goal of carbon peaking and carbon neutrality is a significant strategic decision put forward by China in recent years. It is an important objective leading China's green and low-carbon development, which can bring multiple effects, such as improving environmental quality and advancing industries. Taking Yichun, a typical forestry resource-based city in China, as an example, an economic-environment-carbon emission evaluation indicator system was established and the entropy method and a coupling coordination model were used to calculate the coupling coordination relationship between economic development, environmental quality and carbon emission in Yichun from 2010 to 2020. The results showed that the economic development and environmental quality of Yichun showed an upward trend, but the carbon emissions and intensity increased greatly, and the overall development pattern shifted from the economy lagging to the environmental and carbon emissions lagging. The level of coupling coordination in Yichun had been consistently improving, progressing from severe imbalance and declining development to intermediate coordinated development, and the environmental and carbon emission subsystems needed to be strengthened. Finally, suggestions were proposed to achieve the goal of high-quality economic development, focusing on solving outstanding environmental problems, strengthening energy conservation and efficiency and circular economy, vigorously developing the forestry economy and actively exploring innovative mechanisms of carbon sink product value realization.

Research on carbon emission efficiency of aviation enterprises based on super efficiency SBM model
YANG Yang, GUO Guamei
2023, 13(5): 1779-1786. doi: 10.12153/j.issn.1674-991X.20230095
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In order to identify the carbon emission control level of aviation enterprises, the super efficiency SBM model and GML index model were used to study the carbon emission efficiency and dynamic changes of six aviation enterprises in China from 2011 to 2019. Then a panel regression model was constructed to explore the influencing factors of carbon emission efficiency of aviation enterprises. The results showed that the carbon emission efficiency of China's aviation enterprises showed "U" shaped trend of first decreasing and then increasing during the sample period. Compared with 2016, the carbon emission efficiency of the industry increased by 6.38% in 2019, and the level of carbon emission control of enterprises had improved significantly. In terms of changes of carbon emission efficiency, technological progress and productivity index show similar changes in the same direction, which was the main driving force for carbon emission efficiency. There were great differences in the changes of carbon emission efficiency among different enterprises. As for the influencing factors, seat utilization rate and fuel cost regulation had a significantly positive impact on the carbon emission efficiency of aviation enterprises. When the passenger seat utilization and fuel cost regulations were increased by 1%, respectively, the carbon efficiency was improved by about 1.524% and 0.166%, respectively. Environmental regulations had a positive impact on the improvement of carbon emission efficiency. At this stage, the capital structure had a significant negative impact on carbon emission efficiency, and optimizing enterprise operations and adjusting enterprise capital structure could largely promote the sustainable development of enterprises.

Ecological restoration of the Yellow River basin in the last 70 years and systematic restoration thinking
TIAN Meirong, FENG Chaoyang, WANG Shixi, TIAN Yuxin, NIU Qiantong
2023, 13(5): 1787-1797. doi: 10.12153/j.issn.1674-991X.20221079
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The Yellow River basin is an important ecological security barrier in China. With the continuous strengthening of climate change and human interference, the contradiction between water supply and demand has become prominent and ecological problems have become prominent. Efficient ecological restoration is an important measure to promote ecological protection in the Yellow River basin. Combined with the characteristics and main problems of the Yellow River basin in different historical periods since the establishment of the People's Republic of China, the three stages of continuous exploration and scientific management of the Yellow River basin were summarized, including "water and sediment regulation for controlling water disasters, water source conservation for controlling flow interruption, and system restoration for maintenance health". The ecological governance of the Yellow River basin had achieved good results through the three stages of key projects, but there were still challenges in the systematic restoration of the Yellow River basin. Based on the systematic thinking of ecological restoration, a systematic restoration framework was constructed including four aspects: the systematic nature of watershed ecological space, the systematic nature of ecological elements, the systematic nature of ecological product value, and the systematic nature of ecological supervision. Under the guidance of the systematic restoration framework, the following suggestions were proposed to provide ideas for high-level protection: 1)Based on the site conditions of the upper, middle, and lower reaches of the Yellow River basin, carrying out systematic restoration and governance, implementing policies by different regions, to improve the overall ecological service supply capacity of the basin; 2) Adhering to the life community of mountains, rivers, forests, fields, lakes, grass and sand, carrying out systematic management and optimizing the allocation of ecological elements; 3) Promoting the formation of a composite system for the value transformation of ecological products under ecological restoration, which was coordinated from five dimensions: natural resources, restoration subjects, restoration modes, restoration spaces, and value chains; 4) With the goal of restoring the dominant ecological function, establishing a comprehensive and systematic regulatory system for the ecological restoration process in the Yellow River basin.

Dissolved organic matter distribution characteristics and source analysis of Ulungur Lake during ice sealing period
LU Xiaofeng, ZHU Shanlin, ZHANG Lan, QI Zhenhua, CHEN Jingjing, WANG Kun, BAI Jinfeng
2023, 13(5): 1798-1807. doi: 10.12153/j.issn.1674-991X.20221092
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As the second largest lake in Xinjiang, Ulungur Lake is of great significance in maintaining the ecological balance in the northwest region of China. In order to explore the reasons why the organic indexes of Ulungur Lake exceeded the standard during the ice sealing periods, the dissolved organic matter (DOM) of water body during the ice sealing period was taken as the research object, and the spatial distribution characteristics and source analysis of DOM in Ulungur Lake were discussed by means of ultraviolet-visible absorption spectroscopy and three-dimensional fluorescence spectroscopy combined with parallel factor model (PARAFAC) and correlation analysis. The results showed that the ultraviolet-visible absorption spectrum parameters (E3/E4) of DOM in Ulungur Lake during the ice-sealing period were greater than 3.5, indicating that the water humus was mainly fulvic acid. PARAFAC analysis showed that DOM of Ulungur Lake contained three main fluorescent components, namely terrestrial humus (C1, 39.03%), tryptophan-like substance (C2, 38.20%) and fulvic acid substance (C3, 22.77%). The average fluorescence index (FI), humification index (HIX ) and autochthonous index (BIX) of the water body of Ulungur Lake were 1.64, 1.66 and 1.03, respectively. The fluorescence characteristic parameters showed that the DOM of the water body was composed of terrestrial and autochthonous sources, and had the characteristics of low humification and high autochthonous sources, indicating that the DOM of the water body of Ulungur Lake was mainly produced by endogenous sources. Humus (C1, C3) was significantly correlated with protein-like components (C2) (P< 0.01), indicating that the production and source of humus and protein-like components were consistent. The study on the characteristics of DOM in Ulungur Lake during the ice sealing period could provide a theoretical basis for the treatment of organic pollution in Ulungur Lake.

Analysis of phytoplankton community characteristics and water quality health status in an estuarine composite ecological purification system
XU Xiaoyi, SUN Yidong, JIANG Yongbo, WU Wei, WU Bingdang, HUANG Tianyin, CHEN Xiaobin, MA Yi, ZHU Yi, SONG Xiaoheng
2023, 13(5): 1808-1819. doi: 10.12153/j.issn.1674-991X.20230090
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In view of the actual project of the composite ecological purification system in an estuary of Yangcheng Lake, based on exploring the seasonal composition characteristics of the phytoplankton community in each purification unit, comprehensive evaluation and analysis of water quality health status were carried out by using comprehensive trophic level index (TLI) and phytoplankton diversity index. The results showed that a total of 143 species of phytoplankton from 97 genera and 8 phyla were identified in the purification system, with Diatoma, Chlorophyta, and Cyanophyta dominating the species composition. The phytoplankton intensities of the influent and effluent of the system were 5.81×105-1.76×107 cells/L and 4.96×105-1.65×107 cells/L, respectively, and the biomass ranges were 0.292-5.21 mg/L and 0.194-4.66 mg/L, respectively. The system had an effective control over phytoplankton growth in the water body. According to FG functional group classification method, the phytoplankton in the purification system could be divided into 26 functional groups, among which B, D, MP, P, S1, W1, X2, Y, G, J, LO, and M were the dominant functional groups. The succession of dominant functional groups in each unit correlated well with water quality indices such as water temperature, CODMn, DO, and TN. The water body of the composite purification system was in mesotrophic to slightly eutrophic state during the research period, indicating that the system effectively improved the ecological health of the water entering the lake.

Nitrogen and oxygen isotope analysis of nitrate-nitrogen pollution sources in a typical urban river
GUO Qiuyan, ZHANG Qiuying, SHU Wang, BAI Yangwei, LI Zhao, WEI Yimei, LIU Danni
2023, 13(5): 1820-1828. doi: 10.12153/j.issn.1674-991X.20221288
Abstract(194) HTML (252) PDF(3662KB)(55)
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Nitrate-nitrogen (NO3-N) pollution in urban rivers has become a water environment problem of great concern in the context of rapid urbanization. Taking the Zaohe River in Xi'an City as an example, the river water body, discharge wastewater and inlet and outlet water of wastewater treatment plants were sampled in May (dry season) and September (rainy season) in 2021 to determine the water quality parameters and to resolve their nitrate-nitrogen sources using nitrogen and oxygen stable isotope and Iso Source models. The results showed that δ15N values of nitrate-nitrogen in the Zaohe River ranged from −26.43‰ to 32.29‰ and −2.81‰ to 20.85‰ in May and September, respectively, and δ18O values ranged from −23.42‰ to 53.02‰ and −5.26‰ to 21.53‰, respectively. Manure was the main source of nitrate pollution in the Zaohe River, and the average contribution rate of different nitrate sources in the river was in the order as follows: for river water, manure > soil organic nitrogen > fertilizer > atmospheric deposition; for discharge water, manure > soil organic nitrogen > fertilizer > atmospheric deposition; for sewage treatment plant influent water, atmospheric deposition > manure > soil organic nitrogen > fertilizer; for sewage treatment plant effluent, manure > soil organic nitrogen > fertilizer > atmospheric deposition. The combined contribution of soil organic nitrogen and manure to the Zaohe River watershed was greater than 70%. Therefore, controlling the discharge of residential sewage, strengthening the construction of pipeline networks, enhancing the management of livestock and poultry manure and strengthening the supervision of land fertilization were conducive to reducing the pollution of nitrate-nitrogen in urban rivers.

Removal efficiency of different forms of nitrogen from farmland runoff by adding rice straw in submerged plant wetland
CAI Min, CUI Naxin, ZHANG Xu, CHEN Guifa, ZHOU Li, ZOU Guoyan
2023, 13(5): 1829-1838. doi: 10.12153/j.issn.1674-991X.20230043
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Abstract:

In order to improve the purification efficiency of different forms of nitrogen in farmland runoff by constructed wetlands (CWs) around the paddy field, and effectively intercept nitrogen (N) and phosphorus (P) runoff loss caused by non-point source pollution in farmland, agricultural waste rice straw was used as organic carbon source to enhance the purification capability of CWs planted with submerged plant Vallisneria natans (Lour.) Hara. Four kinds of CWs were set up: without submerged plant (NS), only planted with V. natans (VN), only added with rice straw (SS) and with V. natans planted and rice straw added (VS). The purification performance and mechanism of CWs were studied when treating farmland tail water with ammonia nitrogen (NH4 +-N) or nitrate nitrogen (NO3 -N) as the main N components. The results showed that the purification efficiencies of TN and NH4 +-N in VN and VS were significantly higher than those of NS and SS (P<0.05) in the treatment of farmland tail water with NH4 +-N as the main nitrogen form, which indicated that planting V. natans played a crucial role in the removal of NH4 +-N. The average removal rates of TN and NO3 -N by SS and VS were significantly higher than those of NS and VN CWs (P<0.05) in the treatment of farmland tail water with NO3 -N as the main nitrogen form, suggesting that the addition of rice straw significantly improved the reduction of NO3 -N. CWs only planted with V. natans had poor removal efficiency on NO3 -N. While the removal of NH4 +-N was limited in CWs only added with rice straw. VS showed excellent purification performances on the removal of two forms of N. At the same time, VS showed similar TP removal efficiency to VN. The above results suggested that it was a feasible way to apply this kind of CWs to control agricultural non-point source pollution.

Apparent pollution evaluation and source analysis of river water bodies in the tidal river network area of the plains
LI Haiyun, PAN Yang, ZHANG Longfei, CHEN Xuyu, QIN Tianyu, LÜ Lingxiao, LI Shangke
2023, 13(5): 1839-1848. doi: 10.12153/j.issn.1674-991X.20221119
Abstract(158) HTML (128) PDF(3901KB)(53)
Abstract:

Taking the river course in Dali Town, Foshan City as the research object, the sensation pollution index (SPI) and the classification method of apparent pollution types were utilized to evaluate the apparent pollution status and pollution sources of the river course water in the plain tidal river network area from two perspectives of pollution degree and pollution type, and Positive Matrix Factorization model was used to quantitatively analyze the pollution sources. The results showed that the landscape river in Dali Town, Foshan City had poor overall apparent quality. The apparent pollution type was mainly mixed-dominant and the level of pollution was found to be heavier in summer and late spring compared to early spring. The apparent conditions of different areas were in the order of Zhen Shuiwei Area>Baisha Area>Yan Lianwei Area>Huangi Yanlianwei Area>Xiebian Chong and Xiangjihe Area>Michong Area>Houhai Area. Overall, the apparent quality of the river channel was poor during low tide periods, and the varying tides greatly impacted the perceived apparent quality of the river in the southern region of the town. The types and contribution rates of pollution sources in river channels varied depending on the level and type of pollution. For organic-dominated (black and odorous) water, the primary source of pollution was point sources, accounting for 52.61% of the pollution. Meanwhile, for organic-dominated waters with blooms, agricultural non-point sources contributed the most pollution at 35.98%. In cases of nutrition-led pollution, the primary source was found to be plantation pollution, contributing to 51.43% of the total pollution. Finally, for inorganic-dominated pollution, surface runoff was the main source, accounting for 41.50% of the pollution. In conclusion, it was noteworthy that there existed significant temporal and spatial changes in the apparent pollution levels of the rivers in Dali Town. Furthermore, the pollution sources causing various types of apparent pollution differed, indicating a need to classify and treat them accordingly to enhance overall conditions.

Evaluation on ecological restoration effect of gate-controlled river in plain river network area
FAN Yehong, HE Yan, ZHU Hanbin, ZHAO Kaihao, GU Dungang, HUANG Minsheng, HE Peimin, XU Bingbing, HE WenHui
2023, 13(5): 1849-1856. doi: 10.12153/j.issn.1674-991X.20230104
Abstract(139) HTML (119) PDF(1980KB)(51)
Abstract:

To confront the problem of repeated bloom after urban river control, the Xiaolaigang reach in Qingpu District of Shanghai was taken as the research area and the river ecological restoration effect was evaluated. Based on the combination of analytic hierarchy process and entropy weight methods, referring to relevant studies and field investigations, the evaluation index system was established by optimizing and selecting relevant indicators such as water quality, sediment, and bank protection. The results showed high nitrate content of (3.055±2.863) mg/L, which was significantly correlated with chlorophyll a (r=0.36, P<0.05), was an important potential risk factor for blooms in the gate-controlled plain river network. The aeration mode could be further optimized to create a suitable anoxic microenvironment and enhance total nitrogen removal by coupling sulfur and iron elements, in combination with the existing sluice pump engineering live water smooth flow technology. The sediment of river channel was mainly polluted by nutrient salt with the endogenous nitrogen content of (2171.99±1 664.40) mg/kg. The existing submerged plant species were relatively simple, which was easy to produce filamentous algal blooms. The species of submerged plants could be increased, and the rational allocation could reduce the nutrient salt pollution of the sediment and enhance the stability of the aquatic ecosystem with submerged plants as the core. The purification and interception ability of rainwater runoff pollution by the slurry concrete rigid bank revetment was seriously insufficient. Therefore, the river channel could be properly widened, the ecological transformation of the bank revetment could be carried out, and reasonable filler matrix and vegetation allocation could be selected to strengthen the interception function of the bank revetment on non-point source pollution.

Prediction of effluent COD based on quantum weighted minimal gated unit network
ZHANG Yuze, YAO Lizhong, LUO Haijun
2023, 13(5): 1857-1864. doi: 10.12153/j.issn.1674-991X.20221049
Abstract(164) HTML (90) PDF(1911KB)(28)
Abstract:

Rapid and accurate measurement of effluent chemical oxygen demand (COD) was essential for the dynamic regulation of water quality in wastewater treatment processes. In order to solve the problem of real-time detection of COD in the effluent, a COD prediction method based on quantum weighted minimal gate unit (QWMGU) neural network was proposed. The time series was first constructed through a multi-dimensional single-step (sliding window) prediction technique; then quantum computing mechanism was designed in the links of forgetting gate, candidate state and output of the minimal gated unit (MGU). The network neurons were endowed with quantum characteristics by updating the quantum phase shift gate matrix instead of the MGU weight matrix, and the specific rules and construction process of the QWMGU model design were given. The method was applied to the prediction of effluent COD of the wastewater treatment plant in Dezhou City in 2020 and compared with five usual prediction models to test the model's superiority. The results showed that the relative prediction error of the QWMGU network was better than other methods and more stable, with the root mean square error, coefficient of determination and mean absolute error of 0.073, 1 and 0.047, respectively. The model helped to achieve efficient online detection of COD in wastewater treatment plants.

Effect of magnetic biochar and its aging on the adsorption performance of Cd2+
YANG Ting, XU Rong, KOU Xiangming, ZHANG Jiahong, MA Linjie, ZHANG Chengxin, ZHU Lingyu, YANG Jun, YUAN Qin, WANG Shouhong
2023, 13(5): 1865-1873. doi: 10.12153/j.issn.1674-991X.20221019
Abstract(159) HTML (88) PDF(5766KB)(40)
Abstract:

Magnetic biochar (FBC) is an adsorption material with good adsorption performance and magnetic separation. However, there are few studies on whether the amount of magnetic precursor in the preparation process and the aging effect affect its structure and the ability to adsorb heavy metals. FBC with different iron-carbon ratios (1∶4, 1∶2 and 1∶1, denoted as FBC-4, FBC-2 and FBC-1) were prepared from rice straw and iron salts, and their surface morphology, functional groups and other physical and chemical properties, as well as the adsorption properties of Cd2+ were compared. Two physical aging methods (spontaneous aging and high temperature aging) were used to study the effect of aging on the physicochemical properties and adsorption properties of magnetic biochar. The results showed that compared with ordinary biochar (BC), FBC had a larger specific surface area and pore volume, the number of oxygen-containing functional groups increased, and the characteristic peaks of Fe—O appeared. The saturation magnetization of FBC-4, FBC-2 and FBC-1 increased with the increase of iron content per unit biochar, which were 0.64, 2.21 and 17.69 A·m2/kg, respectively. The adsorption isotherms and kinetic curves of BC and FBC for Cd2+ were consistent with the Langmuir equation and the pseudo-second-order kinetic equation. The relationship between the fitted equilibrium adsorption capacity and the theoretical maximum adsorption capacity was FBC-1>FBC-4>FBC-2>BC, that is, magnetic modification could improve the equilibrium adsorption capacity of Cd2+, and FBC-1 had a stronger adsorption capacity for Cd2+. After two months of spontaneous aging and high temperature aging, the specific surface area of FBC-1 decreased by 45.8% and 36.4%, the average pore size increased by 72.7% and 43.2%, and the saturation magnetization increased to 33.53 and 26.65 A·m2/kg, respectively. Aging could inhibit the adsorption capacity of magnetic biochar for Cd2+. The equilibrium adsorption capacity decreased from 36.97 mg/g before aging to 30.97 mg/g (spontaneous aging) and 28.22 mg/g (high temperature aging), and the theoretical maximum adsorption capacity decreased from 63.80 mg/g to 46.68 mg/g and 40.29 mg/g, respectively. Compared with spontaneous aging, high temperature aging had a more obvious inhibitory effect on the adsorption performance of magnetic biochar for Cd2+.

Tentative study on protein extraction from sweet potato starch processing water by acid-heat flocculation
WANG Xueting, ZHAO Bochao, LUO Min, YUAN Xinan, ZHU Kesong, PAN Cenxuan, ZENG Fankui
2023, 13(5): 1874-1882. doi: 10.12153/j.issn.1674-991X.20230026
Abstract(148) HTML (68) PDF(1630KB)(23)
Abstract:

In the process of sweet potato starch production, a large amount of starch processing water is produced, which contains a lot of protein. The protein extraction from sweet potato starch processing water by acid-heat flocculation was studied. Through the single factor experiment, pH, temperature, centrifugation time and centrifugation speed were selected as variables. The main factors and optimum conditions were studied through orthogonal experiments. While, the effect and technical and economic feasibility of extracting protein from sweet potato starch processing water were analyzed through process simulation test with an integrated device. The results showed that the removal rates of TN and CODCr of sweet potato starch processing water reached 76.79% and 40.66%, respectively, when the temperature was 100 ℃, pH was 4.0, the centrifugation speed was 3 500 r/min and the centrifugation time was 10 min. The process simulation test results of the integrated device showed that the sweet protein recovery rate reached 48.86%, and the protein content (dry basis) of the recovered crude protein powder was 73.22%, which met the requirements of animal feed raw materials. In addition, for a medium-sized or large-sized sweet potato starch enterprise, 1 m3 sweet potato starch processing water could create a gross profit of 20.51 yuan by recycling protein. The protein extraction from sweet potato starch processing water by acid-heat flocculation had both technical and economic feasibility, which had a good promotion prospect.

Research progress on sources, ecotoxicological effect and treatment technology of microplastics in water
WANG Cheng, LI Zhe, WEI Jian, QIAN Feng, SONG Yonghui
2023, 13(5): 1883-1892. doi: 10.12153/j.issn.1674-991X.20221121
Abstract(284) HTML (650) PDF(5258KB)(125)
Abstract:

Microplastics, as one of new pollutants that are widely concerned internationally, have been frequently detected in water environment around the world in recent years. Microplastics not only have the characteristics of small size, difficult degradation and durability, but also can act as carriers of toxic metals, microorganisms and pesticides and other pollutants to further enhance their hazard potentials. A comprehensive understanding of the sources and treatment approaches of microplastics is a prerequisite for identifying critical issues and their effective management. The latest progress of research on microplastic pollution in water environment at home and abroad was reviewed, the classification and sources of microplastics were analyzed, the methods of separation and extraction of microplastics, qualitative and quantitative detection were expounded, and the single effects of microplastics on typical aquatic organisms and the composite effects of microplastics and related pollutants on aquatic organisms were systematically summarized. Combined with the existing water pollution control technology, the advantages and disadvantages of microplastic removal methods, including adsorption, filtration, coagulation precipitation, photocatalysis, electric flocculation, biodegradation, membrane bioreactor and activated sludge process, were summarized. It was expected to provide reference for the removal and pollution control of microplastics in water environment.

Research progress on pretreatment techniques for alkylphenols in environmental water
LIU Haiping, CHEN Xingyu, LU Bingwen, TIAN Zhongnan, ZHAO Yaxian
2023, 13(5): 1893-1900. doi: 10.12153/j.issn.1674-991X.20221272
Abstract(186) HTML (91) PDF(526KB)(34)
Abstract:

As a kind of typical environmental endocrine-disrupting chemicals, alkylphenols can exist stably in the water environment for a long time, and have become great-concern substances by environmental scholars at home and abroad. On the basis of recent literature on the pollution of alkylphenols in environmental water, the principal pretreatment techniques were reviewed, of which commonly used in the analysis and detection of alkylphenol in environmental water were emphatically expounded, including liquid-liquid extraction (LLE), solid-phase extraction (SPE), solid phase micro-extraction (SPME), and so on. The principle, characteristics, influencing factors and practical application of the above methods were introduced. The results showed: 1) Alkylphenols were widely detected in various environmental water at home and abroad, and concentrations were generally between undetected (ND) and several thousand ng/L, which were easy to be adsorbed on suspended solids or colloidal particles in water. It was urgent to establish reliable, efficient and fast pretreatment techniques to lay a good foundation for the accurate determination and quantitative analysis of alkylphenols in water. 2) Compared with SPME and stir bar adsorption extraction, LLE and SPE were superior in the aspect of recovery rate, precision and stability, and both had been applied in the national standard analysis methods of alkylphenols in environmental water in many countries. In the future, research should be strengthened on the extraction capacity and selectivity of fillers, the durability of coatings, and the combination of multiple extraction techniques, to establish rapid, efficient, miniaturized, solvent-free or less solvation, environmentally friendly and automated pretreatment techniques. Also, the management of alkylphenols should be strengthened, being integrated into the water quality standards, discharge standards, etc.

Ecological space zoning and conservation and restoration strategies based on the evaluation of ecosystem "damage-resilience-restoration potential" in Inner Mongolia Autonomous Region
ZHENG Tingting, YANG Li, JIA Zhuofei, AO Nen, JIANG Yadong, LIU Xin
2023, 13(5): 1901-1909. doi: 10.12153/j.issn.1674-991X.20221162
Abstract(307) HTML (149) PDF(3312KB)(72)
Abstract:

In order to build safe and tough ecological space, improve the quality and stability of the ecosystem, and enhance the self-recovery capability of ecological space, Inner Mongolia Autonomous Region was taken as an example to study the ecological restoration zoning methods suitable for large-scale space. In response to typical ecosystem issues in the region, an ecosystem evaluation technical system with the combination of "damage-resilience-restoration potential" was built. By evaluating the current status and damage of the ecosystem, the ecosystem problems and degradation areas were identified. According to the characteristics and support capabilities of the ecosystem, the evaluation of ecosystem resilience and restoration potential was carried out. Coupling multi-level evaluation results, the areas with the same restoration characteristics were identified, and ecological space restoration zones were comprehensively defined. The results showed that the areas with high restoration potential were mainly distributed in areas such as Daxing'an Ridge, Yin Mountain, and Helan Mountain. The areas with medium potential mainly included Hulunbuel meadow grassland, Xilin Guole typical grassland, the northern desert grassland of Yin Mountain, and the Alashan desert, etc. The areas with low potential mainly included Xiliao River Basin, the Yellow River basin, the local grassland, and the desert sand areas. Combined with regional characteristics, 9 ecological space restoration zones were comprehensively defined. From the perspective of promoting the structure, quality, functional protection and restoration of the ecosystem, ecological restoration strategies of protection and conservation, natural recovery, auxiliary restoration, and ecological reshaping were proposed according to local conditions, to ensure that the regional ecosystem realized virtuous circulation and self-regulation. Starting from the three levels of ecosystem damage, resilience and restoration potential, an ecological evaluation technical system was established, the ecological space restoration zones was delineated, and methods and implementation paths suitable for large-scale ecological space governance were proposed.

Research of ecological security patterns based on ecosystem services value in Chengdu-Deyang-Mianyang city belt
DENG Yingjia, HOU Langong, LIU Tao, WANG Jing
2023, 13(5): 1910-1920. doi: 10.12153/j.issn.1674-991X.20221057
Abstract(233) HTML (154) PDF(4062KB)(40)
Abstract:

Quantitative research and analysis of the ecosystem services value (ESV) change and ecological security pattern in Chengdu-Deyang-Mianyang (CDM) city belt are crucial for cross-administrative coordination to build an ecological security barrier, strengthen ecosystem protection, advance the ecological restoration planning, and promote the construction of ecological civilization. The spatial and temporal variations of ESV in CDM city belt from 2010 to 2018 were analyzed using ESV equivalence method. Then, 99%, 95% and 90% confidence level ESV hotspots in the region were extracted and the core "source" ecological protection areas were identified. Eight important resistance factors such as elevation and land use were selected to obtain the resistance surface, and the minimal cumulative resistance model was used to construct the regional ecological corridors and identify the ecological security patterns in urban belts. The optimization suggestions of the spatial layout of ecological networks across administrations were proposed. The results showed that from 2010 to 2018, the total value of ecosystem services in the study area increased from 137.291 billion to 151.993 billion, with growth rates above 10 percent for raw materials, gas regulation, climate regulation, waste disposal, soil formation and conservation, and biodiversity conservation. The ecological safety level of the study area showed a spatial distribution characterized by a high level in the northwest and a low level in the southeast, 49.8% of which were with the highest and second-highest safety levels and concentrated in the northwest, south-central and other regions. The medium- and low-security zones accounted for 50.2 percent of the total, mainly concentrated in low-altitude urban areas such as construction sites in the south. 24 ecological "source" sites were identified, accounting for 27.3% of the total area of the study area, and were distributed in a zonal pattern; fifty-three ecological corridors and forty-one ecological nodes were identified, showing an overall polycentric ring shape and an excellent overall level of network connectivity. Based on the research results, the spatial structure of the ecological network of "two axes, three belts and four nodes" was constructed in the northwest (dense) and southeast (sparse), which provided references and suggestions for regional ecological security.

Analysis of spatiotemporal heterogeneity of habitat quality and their driving factors based on optimal parameters-based geographic detector for Fuzhou City, China
SHI Zhiyong, XIE Huili, WANG Zhenfeng, HU Xiaoting, WANG Xinke, XIE Xiangqun, LIN Hong, LIU Xingzhao
2023, 13(5): 1921-1930. doi: 10.12153/j.issn.1674-991X.20230083
Abstract(448) HTML (307) PDF(8523KB)(91)
Abstract:

Revealing the spatiotemporal evolution characteristics of habitat quality and their influencing factors can provide reference basis for regional sustainable development. Based on the land use data in 2000, 2010 and 2020, InVEST model, landuse transfer matrix and optimal parameters-based geographical detector (OPGD) were used to comprehensively analyze the spatiotemporal evolution and driving factors of habitat quality in Fuzhou City. The results revealed that the habitat quality index of Fuzhou City in 2000, 2010 and 2020 was 0.812, 0.806 and 0.793, respectively. The area of habitat improvement was less than the area of habitat deterioration. Habitat conditions in the main urban area of Fuzhou and the southeast coastal region were in urgent need of improvement. 3 km was the best optional spatial unit for this study, the optimal data discretization classification number is 6, and the natural break method better explained the explanatory power of the driving factors. Elevation, slope and night-time lights were the main influencing factors of spatial variation in habitat quality in Fuzhou City, and the interaction of slope and nighttime lights had the strongest explanation for habitat quality changes.

Construction and analysis of county water security pattern in mountainous areas of northern Guangdong Province from a comprehensive perspective
CHEN Zhao, YANG Xianfang, CHEN Jindong, WANG Qi, LIU Ting, DENG Nanrong
2023, 13(5): 1931-1940. doi: 10.12153/j.issn.1674-991X.20220919
Abstract(177) HTML (112) PDF(8294KB)(35)
Abstract:

Taking Wengyuan County in the mountainous area of northern Guangdong Province as an example, the authoritative research data sources in the fields of water resources, water hazards and water environment were adopted, combined with data on county topography, hydrology, ecological protection, land status survey, measured water quality sampling, etc., as well as related planning and standards. By using the methods of Euclidean distance buffer for water source combined with conservation capacity calculation, Bluespot model simulation and water environment load calculation, the regional water resources, water hazard and water environment security pattern were calculated and analyzed. On this basis, a comprehensive water security pattern under regional multi-perspectives was constructed. The analysis results showed that the security patterns of water resources, water hazards and water environment in Wengyuan County were closely related to the important water systems and related protected areas and landforms, the location of the upper, middle and lower reaches of Wengjiang River system and the surrounding intensity of human activities, and the pollution status of the water bodies, respectively. The low security areas in the comprehensive water security pattern of Wengyuan County were mainly distributed in ecologically sensitive and fragile areas such as drinking water sources, nature reserves, important water system corridors and water conservation areas and surrounding areas; the medium security areas were mainly distributed in the buffer zone of the low security ecologically sensitive and fragile area, including the adjacent affected area; the high security areas were mainly distributed in the periphery of the medium security buffer zone and its adjacent affected areas. In the comprehensive water security pattern of Wengyuan County, there was a small area conflict control area between the sensitive and fragile low security area and the construction land and permanent basic farmland protection area. However, it had a high degree of agreement with the redline of ecological conservation and the management space of soil and water conservation, which showed that the research results were in good agreement with the space of land management, related protection planning and practical management.

Analysis of the limits of air pollutants at enterprise boundary based on ambient multimedia environmental goals estimation
ZHANG Mengqi, PAN Libo, WANG Zongshuang, GUO Min, WU Xuefang
2023, 13(5): 1941-1947. doi: 10.12153/j.issn.1674-991X.20230381
Abstract(142) HTML (68) PDF(946KB)(27)
Abstract:

Thirty-six air pollutants with established enterprise boundary limits were screened out from more than 40 national emission standards for stationary air pollutants sources and local emission standards for odor pollutants. A method suitable for limit analysis was proposed, and a reference interval was set based on the ambient multimedia environmental goals (AMEG). The difference in the occupational exposure limits time-weighted average allowable concentration (TWA) of chemical harmful factors between China and the United States was compared and analyzed. The results showed that the 36 air pollutants could be divided into three categories. Firstly, there were 8 pollutants that appeared in the national integrated emission standards for air pollutants and other standards that had been formulated and published for a long time with loose limits. Secondly, there were 13 pollutants whose limits were not affected by olfactory thresholds, among which the limits of 12 pollutants were close to 8.4 times of AMEG estimation. Thirdly, there were 15 pollutants whose limits were affected by olfactory thresholds, among which the limits of some pollutants were close to AMEG estimation, and some were close to olfactory thresholds. Among the 255 chemical harmful factors involved in the comparative analysis, there were 44 chemical harmful factors with TWA equivalent in China and the United States, accounting for no more than 20 percent, nearly 85 percent with a difference within ±1 time, and 7 percent with a difference of more than ±5 times. The research showed that the enterprise boundary limits in the current air pollutant emission standards had effectively protected human health and ecological environment. However, the standards that had been formulated and published for a long time with loose limits, as well as limits of the standards higher than olfactory thresholds, should be studied to analyze the reasonableness of the limits. Occupational exposure limits data from more sources should be widely collected and their applicability should be analyzed when formulating the limits of air pollutants at enterprise boundaries.

Research on the path to achieve the goal of realizing "zero-waste" of coal gangue in China
HOU Bo, MA Chao, TIAN Xiangqin, NIE Jinglei, ZHAO Kang
2023, 13(5): 1948-1957. doi: 10.12153/j.issn.1674-991X.20221279
Abstract(148) HTML (266) PDF(2389KB)(83)
Abstract:

In order to solve the environmental pollution problems caused by the massive accumulation of coal gangue, the goal of realizing "zero-waste" of coal gangue was proposed based on the concept and experience of "zero-waste city". Based on the analysis of the generation, distribution, and physicochemical properties of coal gangue in China, the necessity of the goal of realizing "zero-waste" of coal gangue was discussed from two aspects of the clean and efficient utilization of coal and the reduction of pollution and carbon. The policy basis, technical status quo and existing problems of achieving the goal of realizing "zero-waste" of coal gangue in China were analyzed. It was suggested that China should carry out the work in four aspects: building green ecological coal mines, improving the comprehensive utilization rate of coal gangue, researching and developing technologies for comprehensive utilization of coal gangue resources, and formulating product standards for comprehensive utilization of coal gangue. It was suggested to accelerate the industrialization application of coal gangue comprehensive utilization technologies centered on the integration of underground coal dressing and backfilling, mine filling, pit backfilling, and ecological restoration of collapsed areas, and build a resource-based utilization industrial chain of "power generation - recycling or utilization of useful (valuable) components - high-performance building materials or agricultural applications or mine backfilling" to realize the high-value utilization of multi-component gradation in coal gangue. These measures would ensure the smooth realization of the goal of realizing "zero-waste" of coal gangue in China.

Factors influencing risk of droplet transmission in pavilion nucleic acid sampling environment
LI Jingming, ZHANG Zhenyu
2023, 13(5): 1958-1964. doi: 10.12153/j.issn.1674-991X.20221211
Abstract(243) HTML (84) PDF(6033KB)(30)
Abstract:

In order to explore the risk of droplet transmission in the nucleic acid sampling environment, the RNG k-ε, DPM and DRW models were adopted to study the droplet transmission process and influencing factors in the nucleic acid sampling pavilion on the basis of Taguchi experiment. The effects of initial droplet speed, airflow organization and fresh vent velocity on the characteristics of droplet transmission were analyzed. It was found that the airflow organization was the principal factor of the droplet transmission, and the up-in and down-out ventilation mode with the maximum ventilating speed of 1 m/s could effectively reduce the risk of droplet transmission under the premise of thermal comfort of the body. The droplet concentration tended to decrease as times went on, the higher the fresh vent speed, the shorter the duration of high-concentration of droplets, and the concentration of droplets dropped to below 7.7% of the limit droplet concentration in the respiratory area after 20 s. With the consideration of efficiency, sampling should be completed as soon as possible and the sampling interval should be extended to more than 20 s to reduce the risk of transmission.