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Table of Content

Volume 38 Issue 10
25 October 2022
Experience and Optimisation of the Traditional Industrial Development and Transformation in Protected Areas: A Case Study of Tea Industries in Wuyishan National Park
WANG Bo-jie, HE Si-yuan, MIN Qing-wen
2022, 38(10):  1229-1238.  doi:10.19741/j.issn.1673-4831.2022.0244
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Many traditional agricultural production systems exist in protected areas. These traditional systems are not only influential to the local sustainable livelihood and cultural inheritance, but also influential to biodiversity and ecosystem conservation outcomes. However, current industry studies seldom focus on the relationship between nature conservation and rural community economic development, or they rarely consider protected area management and demand. This research takes Wuyishan National Park as a case to focus on the traditional tea industry. Using a qualitative research method, this paper analyses the leading ideology, paths, and outcomes of regional industry development over the past 20 years, and provides countermeasures to the development of the tea industry. Results show that the tea industry in Wuyishan has been the interface of community livelihood and protected area management, although the transformation and development process has not interacted well with conservation management demand in general. In specific, the ecologisation, standardisation, and scaling of the tea industry, the promotion of the tea branding effect, as well as integrated development of tea production and tourism, have been realised to some extent; However, there are still old problems and variances under the new national park management, namely the scientific evaluation and realisation of ecological values of products and services, the identification and inheritance of cultural values, and the communication and consensus of multi-stakeholders. The research further proposes developing an ecological tea industry and expanding agriculture to tourism as two major industrial development goals. To achieve these goals, it is necessary to use local ecological knowledge as a base, to form scientific management standards, unite producers and operators of different scales, and seek a variety of value-added opportunities. In this way of tea industry ecologisation and valorisation of ecological value from multi-functionality, it is promising to finally implement the "human-centered" conservation concept in nature conservation from the full play of the social, economic, and ecological values of the traditional community industries.
Research on the Influencing Factors of Coupling Development of the Fuzhou Jasmine Tea Culture System and the Tourism Industry
LAI Ge-ying, DENG Ming-ming, MA Yun-meng, LAI Yi-tian
2022, 38(10):  1239-1248.  doi:10.19741/j.issn.1673-4831.2022.0599
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In the process of inheritance and protecting agro-cultural heritage, as a traditional agricultural production system combined with leisure agriculture and rural tourism, it can not only give full play to the production function among the many functions of agro-cultural heritage, but also realize the role of inheritance and protection of excellent farming culture in the process of combination, and promote the sustainable development of important agro-cultural heritage. However, research on quantitative analysis of coupling development of the agro-cultural heritage and tourism industry and extraction influencing factors remains insufficient. This study takes the globally Important Agricultural Heritage Fuzhou Jasmine and Tea Culture System (Chinese first list of important agricultural heritage in 2013) as an example, constructs a coupling evaluation index system of agro-cultural heritage and tourism industry with a hierarchical and favorable evaluation, analyses the comprehensive development level, the coupling coordination degree and the coupling influence factors of the tea culture system and tourism industry from 2008 to 2020, so as to provide reference for subsequent optimization strategies and research by assessing the status of protection and development of the heritage system before and after being selected. Results show that: (1) At the evaluation of the comprehensive development level, the development of Fuzhou Jasmine and Tea Culture System as a global agro-cultural heritage is good and shows a continuous upward trend. (2) At the coupling coordination development level, they are at a high level of coupling, but with a low degree of fluctuation. (3) At the analysis level of measuring the drivers and obstacles affecting the two coupling development, the correlation degree of the influencing factors calculated by the gray relational analysis method is generally above 0.6, indicating that the coupling correlation degree is high.
The Transition of the Food System for A Nature-positive World: A GIAHS-based Solution
HE Si-yuan, JIAO Wen-jun, MIN Qing-wen
2022, 38(10):  1249-1257.  doi:10.19741/j.issn.1673-4831.2022.0621
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In 2020, the international community proposed the Nature-Positive Global Goal for Nature. Nature-positive means halting and reversing nature loss by 2030, measured from a baseline of 2020. The transition of the current agricultural and food system to a nature-positive food system is critical to halt and reverse the nature loss. This approach aims at curbing the land productivity degradation, resource depletion, and biodiversity loss caused by the food production system, thus maintaining the sustainability of the food system. The Food and Agriculture Organisation (FAO) of the United Nations launched the Globally Important Agricultural Heritage Systems (GIAHS) in 2002. After 20 years of research and conservation practice, we have gained an increasing understanding of the formation and evolution of the agricultural heritage systems, their ecological and social sustainability, and multiple functions and values. GIAHS is proved possible to provide new solutions to the global crisis including climate change, biodiversity loss, environmental pollution, and the degradation of agricultural ecological functions. However, their potential as nature-based solutions is yet to be fully recognised, and the systematic approaches to a nature-positive food system and sustainable development goals are yet to establish. Therefore, based on the literature review, we analysed the feasibility of GIAHS to facilitate the revolutionary change of the global agriculture production and food system from the perspective of nature-positive. We also proposed urgent research and practical requirements based on the demand and challenges of transitioning the food system. We found that the holistic view of GIAHS as a living system is a manifestation of the conceptual shift in the nature-positive global goals. The functions and the mechanism of GIAHS can facilitate the shift to agroecology for a sustainable food system. They are capable to provide the three routes as nature-based solutions: 1) to protect the natural system from degrading and land use change; 2) to sustainably manage the production system to provide ecosystem services and maintain landscape resilience, and 3) to restore certain productivity of degraded ecosystems and improve their functions and services. We should also strengthen research and improve governance to give full play to the agricultural heritage system in achieving a nature-positive food system.
Diversity of Resource Plants and Associated Traditional Knowledge in the Honghe Hani Terraced Ecosystem of Yunnan
ZHANG Qing, CHENG Zhuo, LIU Bo, YANG Jun, LI Jian-qin, ZHANG Hong-zhen, ZHANG Xin-bo, MA Li-juan, LONG Chun-lin
2022, 38(10):  1258-1264.  doi:10.19741/j.issn.1673-4831.2022.0603
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As a site of Globally Important Agricultural Heritage Systems (GIAHS) and a World Cultural Heritage, there is rich biodiversity in Yunnan's Honghe Hani terraced paddy rice fields with important ecological, economic and social values. Resource plants refer to the plants that are beneficial and available to human beings, often carrying rich traditional knowledge of collection, utilization and management of plants, and showing the reciprocal relationship between man and plants. The Hani terraced ecosystem is composed of forests, villages, terraced rice paddies and water systems in Honghe Hani and Yi Autonomous Prefecture, Yunnan, Southwest China. Plants, in particular useful plants, as the crucial component of this ecosystem for maintaining its stability, unfortunately, has always been overlooked. Through the methods of plant taxonomy, plant ecology and ethnobotany, the present study revealed the status of major resource plant diversity and associated traditional knowledge of the Hani terraced ecosystem. The sampling areas covered the paddy rice fields together with their surrounding forest lands from four counties with most Hani terraces in Honghe Prefecture. The relationship between the Hani terraced rice ecosystem and plant diversity has been analyzed. The results show that there are 651 species of useful plants in the Hani terraced ecosystem, including 255 medicinal plant species and 226 edible plant species. The local people have rich traditional knowledge in the management and utilization of these plants, such as the scared forests and trees, edible and medicinal plants, cultivation of Amomum tsaoko and Strobilanthes cusia, and firewood collection. The plants can be used for daily production, livelihood and protection of Hani terraced paddy rice fields with obvious characteristics of the resources of multi-purposes and multi-functions, indicating the profound plant utilization culture and the close human-land interaction on which the stability of agricultural heritage will depend. The local rich plant diversity formed the basis of Hani terraced rice field ecosystem. The long-term collection, management and use of plant resources reflected traditional knowledge and culture, and supported local people's livelihood. The rich plant diversity, combined with its traditional knowledge, plays a very important role in maintaining the entire Hani terraced agroecosystem, conserving agricultural heritage and promoting rural economy.
Application of MaxEnt and Remote Sensing Technology in Grassland Locust Disaster Risk Monitoring: An Example from the Agricultural Heritage Systems of East Ujimqin Banner
SUN Zhong-xiang, HU Ze-xue, YE Hui-chun, HUANG Wen-jiang, Erden Qimuge, ZHANG Ying
2022, 38(10):  1265-1272.  doi:10.19741/j.issn.1673-4831.2022.0600
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The nomadic production system of East Ujimqi Banner is an important agro-cultural heritage system in China with high ecological, economic, landscape, technological and cultural values. However, in recent years the local area has been suffering from locust disaster and the grassland is facing unprecedented threats and challenges. East Ujimqin Banner was selected as the study area, and an occurrence risk index system of grassland locust was built based on remote sensing, soil, vegetation, and topography data as well as maximum entropy model (MaxEnt), combined with grassland locust growth characteristics, to analyze the influence of different habitat factors on grassland locust occurrence. The occurrence risk areas of grassland locust in the study area were then extracted and graded. The results show that the simulated results of MaxEnt model are good with an average AUC value of 0.826. The main factors determining the occurrence risk of grassland locust are surface temperature during the incubation period, surface temperature during the growing period, and precipitation during the egg-laying period. The high-risk areas are mainly located in Gadabchi town with the area of 920 km2. The results of the study are beneficial to better protect the agro-cultural heritage of nomadic production system in East Ujimqi Banner and can provide technical support for disaster risk monitoring of other grassland agro-cultural heritage as well.
Study on Driving Factors of Pollution and Carbon Reduction in the Yangtze River Delta Urban Agglomerations
MA Wei-bo, ZHAO Li-jun, WANG Nan, ZHANG Long-jiang, LI Hai-dong
2022, 38(10):  1273-1281.  doi:10.19741/j.issn.1673-4831.2022.0125
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Urban development is simultaneously facing multiple pressures of climate change, ecological protection, and economic development. Therefore, exploring the characteristics of spatial and temporal driving factors for pollution and carbon reduction at the urban agglomeration scale and their evolution characteristics will help us develop a better understanding of the interaction between urbanization and the environment. Taking the Yangtze River Delta Urban Agglomeration (YRDUA) as the research object, the Index of Pollution and Carbon Reduction (IPCR) is constructed on the basis of carbon emission levels and pollutant emission data. Moreover, the spatial and temporal driving characteristics of economic development, industrial structure, land use structure, population, and climate change on the IPCR and the changes in the importance of the driving factors are analyzed by the Geographically and Temporally Weighted Regression (GTWR) and Random Forest (RF) methods. The results show that: from 2003 to 2017, the overall IPCR of the YRDUA showed a downward trend, with the average IPCR of the 27 cities decreasing from 0.23 in 2003 to 0.05 in 2017; during this period, Chuzhou was still in the higher echelon of the average IPCR, with the amplitude of variation 18.62%. Considering the time effect, the adjusted R2 and R2 of the GTWR model are higher than 0.96, which improves the fitting accuracy and superiority compared with the GWR model. Shanghai, Suzhou, and nine cities in Zhejiang province are negatively driven by the size of landscaped green areas, which leads to the IPCR decrease. Total energy consumption ranks 1st in importance in three periods, 2003-2007, 2008-2012, and 2013-2017, while landscaped green area gradually increased in importance from the 5th in 2003-2007 to the 2nd in 2013-2017. Although population density and total population ranked lower, the overall importance registered an upward trend. Generally speaking, the GTWR model has an excellent spatial and temporal fitting ability for the IPCR, and the spatial and temporal effects of the IPCR are significant. We suggest that the YRDUA to improve energy utilization efficiency, increase efforts on developing tertiary industries and optimize land use structure.
Study on the Carbon Saving Value of Urban Greenspace Patches in the Main Cities of Yangtze River Delta Based on the Cooling Effect
QIU Kuan-biao, DU Han-bei, ZHANG Long-jiang, ZHANG Wei-dong, LI Hai-dong
2022, 38(10):  1282-1289.  doi:10.19741/j.issn.1673-4831.2022.0142
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The vegetation carbon sink has been estimated from the absorption and storage of CO2 through photosynthesis. However, due to its ecological functions such as the local cool island effect of the urban greenspace, little attention has been paid to the energy saving and carbon reduction, and there is a lack of estimation of carbon saving amount in regional cities. Based on the important ecological function of cooling effect of urban green space, this study used buffer analysis and statistical analysis methods to analyze the carbon saving of urban greenspace in 27 core cities in the integrated central area of the Yangtze River Delta (CCICAYRD). Results show that the urban greenspace in the downtown of CCICAYRD had a significant cooling effect. The average LST of urban greenspace was 2.18 K, lower than that of the downtown, and the cooling range was between 2.9 and 8.3 K, and the cooling distance of greenspace patches was between 270 and 450 m. The carbon saving estimation show that the total carbon saving of the 27 core cities in the CCICAYRD was approximately 267 656.12 t·d-1, with an average carbon saving of 9 913.19 t·d-1 per city. Among the major cities, the carbon saving of urban greenspace in Shanghai downtown was the largest, reached to 47 374.83 t·d-1, followed by Wenzhou, Ningbo, Nanjing, Hangzhou, Tāizhou, Suzhou, Wuxi and Hefei, while the carbon saving of urban greenspace patches was small in Xuancheng, Shaoxing, Jiaxing, Chizhou, Ma'anshan and Anqing, all below 2 000 t·d-1. In addition, as the distance to the greenspace patches increased, the carbon saving of the urban greenspace gradually decreased from 3 562.54 t·d-1 in the cooling distance of 0-90 m to 54.20 t·d-1 in the cooling distance of >180-270 m. This conclusion can provide a scientific reference for the urban ecological construction and the researches on urban carbon peaking and neutrality.
Study on Carbon Storage Change and Optimization of Land Use in Jiangyin City
ZHAO Yi-xing, GAO Run-yi, LI Hai-dong, CHUAI Xiao-wei, GUO Xiao-min
2022, 38(10):  1290-1298.  doi:10.19741/j.issn.1673-4831.2022.0491
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The carbon effect of land use change and its impact on climate change have been the focus of academic circles at home and abroad since the 1990s. Under the goal of carbon neutralization, how to achieve the purpose of carbon increase and emission reduction by optimizing land use is a new opportunity and challenge for the current academic research and natural resources authorities. Taking Jiangyin City as an example, this paper analyzes land use change of the city from 2000 to 2015 and its corresponding changes of vegetation carbon and soil carbon storage, and puts forward optimization suggestions for the future land use structure. The main conclusions are as follows: (1) From 2000 to 2015, the cultivated land area in Jiangyin City decreased year by year, mainly transformed into construction land, and the change range of other land use types is small. (2) Due to land use change, the carbon storage of vegetation in Jiangyin City decreased by 75 009.49 t and the carbon storage of soil decreased by 7 641.56 t. Among them, the transfer out of cultivated land and forest land led to the largest loss of carbon storage. (3) According to the historical land use change of Jiangyin City, based on the goal of maximizing carbon reserves, this paper puts forward suggestions on the optimization of land use structure in Jiangyin City. The results show that under the optimization mode, the carbon reserves of Jiangyin ecosystem will reach to 4.55 million t in 2030, an increase of 2 900 t compared with the natural growth mode.
Research on Ecological Construction Model of Villages and Townships in the Important Area of Water Conservation and Biodiversity Conservation in Daloushan Mountains
CHEN Yan, WANG Nan, ZHAO Li-jun, FENG Yang, LI Hai-dong
2022, 38(10):  1299-1308.  doi:10.19741/j.issn.1673-4831.2022.0072
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Ecological construction of villages and townships is a key step to realize rural revitalization. The study on the summarizing of models and influencing factors in the process of village ecological construction is of great theoretical and practical significance to promote the coordinated development of regional ecological, social and economic systems. In this study, the important area of water conservation and biodiversity protection in Daloushan mountains (hereinafter referred to as "Daloushan area") was taken as the research object, and the Principal Component Analysis (PCA) was applied to study the influencing factors of its villages and townships' ecological construction, and its villages and townships’ ecological construction mode was studied through the ideas of "binding points with area" and "from point to area". The results show that: 1) The ecological construction of villages and townships in the Daloushan area is influenced by the combination of human settlements factors (A1), economic development factors (A2) and ecological environment factors (A3), of which the role of A2 is the most significant, among the 16 typical villages and townships selected in the Daloushan area, the villages construction of Loushanguan subdistrict (T5), Bing'an Township (T8), Tiantai Township (T9), Maotai Township (T13), Heishu Township (T14), Yile Township (T15) and Shuitian Township (T16) is more significantly influenced by the ecological environment factor (A3), the human settlement environment factor (A1) and economic development factor (A2) also have significantly effects on Loushanguan subdistrict (T5) and Maotai Township (T13); 2) The ecological construction of villages and townships in the Daloushan area includes four paths and twelve modes, which are developing ecological economy to boost rural revitalization (L1), restoring lucid waters and lush mountains to activate rural revitalization (L2), improving human living environment to empower rural revitalization (L3), and innovating institutional mechanism to consolidate rural revitalization (L4). The above research results are of great significance to promote ecological construction and rural revitalization in the Daloushan area, and also provide demonstration cases for the construction of beautiful villages nationwide.
Analysis of the Spatial-temporal Evolution and Driving Factors of Rural Residential Areas in Metropolitan Fringe: A Case Study of Tianjin
LI Xue-mei, LIU Qian
2022, 38(10):  1309-1317.  doi:10.19741/j.issn.1673-4831.2021.0774
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Excavate thoroughly and fully the spatial-temporal evolution characteristics and influencing factors of rural settlements in metropolis fringe is of great practical significance for the spatial optimization of rural settlements, economical promotion and intensive use of land resources during the urbanization process. Based on Landsat TM remote sensing, the land use information of 450 rural settlements in Tianjin in 1980, 2000 and 2019 were obtained by using ArcGIS software. The spatial overlap analysis, kernel density analysis and structural equation model were used to reveal the spatial and temporal evolution and influencing factors of rural settlements in the past 40 years. The results show that the number of rural settlements decreased from 426 in 1980 to 127 in 2019. There were 355 unchanged villages from 1980 to 2000, while there were 322 decreasing villages and 81 unchanged villages from 2000 to 2019. The spatial distribution of rural settlements showed the characteristics of agglomeration. However, the estimated core density of rural settlements gradually decreased from 1980 to 2019, which showed fewer high-density areas and almost no rural settlements near the central urban area. Regional economy and household behavior have direct impact on the change of rural settlements, while family endowment and government policy indirectly promoted the change of rural settlements through economic development.
LUCC Spatial Simulation of Urban Agglomeration in Central Yunnan
LI Xing, ZHOU Jing-chun, JIN Ting-ting, WANG Jin-liang
2022, 38(10):  1318-1329.  doi:10.19741/j.issn.1673-4831.2021.0540
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Taking the urban agglomeration in Central Yunnan Province as the research area, based on the LUCC data in 2000, 2010 and 2020, combined with correlation analysis, the potential LUCC driving factors were selected to construct the flu model to simulate the LUCC in the study area in 2035. On this basis, the temporal and spatial evolution characteristics and spatial pattern effects of LUCC in different time periods from 2000 to 2035 are analyzed. The results show that (1) the land use types in the study area are mainly dominated by cultivated land, forest land and grassland, and the overall pattern is relatively stable. From 2000 to 2020, the construction land mainly came from a large amount of occupation of cultivated land, and the change rate from 2010 to 2020 was significantly faster than that from 2000 to 2010; (2) According to the prediction, in the next 15 years from 2020 to 2035, the construction land will mainly come from the occupation of forest land, and the urban expansion has obvious direction; (3) The comprehensive degree of land use in most counties and cities shows an upward trend, and there is a decline in the comprehensive degree of land use in some counties and cities due to the implementation of the policy of returning farmland to forest and grassland; The hot spots of utilization degree change are mainly concentrated in the counties and cities in the middle and east, showing a trend of multi-center development; (4) The changes of landscape pattern index in each region are different. On the whole, the degree of landscape fragmentation increases and the diversity decreases. Under the background of western development strategy and accelerated urbanization process, this study discusses the land use characteristics of mountainous urban agglomeration in central Yunnan, simulates the future land use, and quantitatively analyzes the spatial pattern and its change effect, which is of great significance to formulate land space planning, realize "multiple compliance", and clarify the objectives of land space development and protection.
Effects of Non-cultivated Patch on Landscape Heterogeneity of Cultivated Land System in Changtu County, Liaoning Province
BIAN Zhen-xing, GUAN Ming-hao, TONG Hao-xuan, YANG Yu-jing, CHU Zhuo-ming, YU Miao
2022, 38(10):  1330-1337.  doi:10.19741/j.issn.1673-4831.2021.0521
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Landscape heterogeneity is the basis for maintaining biodiversity and ecosystem services in cultivated land system. To explore the effect of non-cultivated land on landscape heterogeneity of cultivated land system, taking Changtu county of Liaoning Province as the study area, Rao quadratic entropy index (Q) was used to characterize landscape heterogeneity based on grid units, and the effect of non-arable patches on landscape heterogeneity was investigated by redundancy analysis, independent sample T test, regression analysis and other methods. The results indicate that: (1) when the proportion of non-arable land of the sample grid units was similar, there was a significant difference in landscape heterogeneity. When the proportion of non-arable land of the sample grid units was 8%, the difference of landscape heterogeneity between the units was the largest. (2) Forest land, grassland, rural road, water area and ditch had significant positive effects on landscape heterogeneity (P<0.01), and forest land had the greatest effect. (3) The mean nearest neighbor distance index (ENN-MN) of non-arable land patches in grid units with different landscape heterogeneity was significantly different (P<0.05). The stronger the non-arable patch connectivity was, the stronger the landscape heterogeneity was. This paper can provide reference for the ecological management and protection of cultivated land in the context of strictly protecting the red line of cultivated land.
Characteristics of Dynamic Changes of Soil Microbial Biomass on Fallowed Farmland of Different Years in Minqin Oasis
WANG Li-de, HE Hong-sheng, HAN Fu-gui, CHEN Si-hang, SONG Da-cheng, WANG Zi-xuan, YAN Pei-ying
2022, 38(10):  1338-1346.  doi:10.19741/j.issn.1673-4831.2021.0701
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In order to investigate the effect of different years of fallowed farmland on soil microbial characteristics, different ages of fallowed farmland (1, 2, 3, 5, 8, 15, 24, 31 a) in Minqin Oasis were used for the study. The spatial scale instead of the temporal scale was used to study the characteristics of soil microbial biomass and its seasonal dynamics in the secondary grassland of Minqin Oasis for different years (1-31 a). The results show that (1) soil microorganisms were higher in the surface layer than in the deep layers of the secondary grassland in the same years of fallowing, The highest soil microbial carbon content of the surface layer was 979.13 mg·kg-1, while the highest soil microbial carbon content was 610, 480 and 327.74 mg·kg-1 with the soil depth of 10-20, >20-30 and >30-40 cm, respectively, accounting for 62%, 49%, 33% of the contents in the surface layer, respectively. Soil microbial biomass nitrogen and soil microbial biomass phosphorus had the same results, indicating that the soil microbial biomass clustering was obvious; (2) soil microbial biomass carbon and microbial biomass nitrogen generally showed a fluctuating decrease with the increase of fallowing years, and soil microbial biomass phosphorus showed a trend of undulating increase with the increase of fallowing years; (3) the dynamic change of soil microbial biomass carbon content with different seasons was obvious, with the minimum in winter, the maximum in autumn, and the medium in summer and spring, and the range of soil microbial biomass carbon content in the surface layer (0-10 cm) was large; (4) the seasonal dynamics of microbial biomass nitrogen showed an inverted V-shaped distribution, and the dynamic change of it was the same as that of microbial biomass carbon. (5) the seasonal dynamics of soil microbial biomass phosphorus content were larger in autumn and summer, intermediate in spring and minimal in winter. From March onwards, soil microbial biomass phosphorus gradually increased as the month increases, reaching a peak in June or September, and then decreased continuously, falling to a minimum in December. (6) According to the research, it can be concluded that the first five years was the key period for the restoration process of fallowed farmland in Minqin Oasis.
High-efficiency Treatment of Eutrophic Surface Water by Flocculation-microbubble Air Flotation
GU Yuan, GUO Shi-yu, ZHAO Wen-tao, WAN Yong, SUI Qian
2022, 38(10):  1347-1353.  doi:10.19741/j.issn.1673-4831.2021.0800
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Aiming at algae blooms and phosphorus pollution in eutrophic surface water, a microbubble flotation device on basis of enhanced flocculation was developed for algae and phosphorus removal for emergency pollution control. The size and spatial distribution of microbubbles in the air flotation device were measured using a high-speed camera. The type, substance content and dosage of the coagulant were optimized to realize the efficient removal of algae and total phosphorus and reduction of turbidity. The results show that the developed air flotation device can generate stable microbubbles at the pressure of 0.32 MPa. The size of microbubbles increased gradually with the flow in ascending and horizontal directions, yet the mean diameter was within the optimal range of air bubbles for removal of algae (21.6-34.4 μm). When polyaluminum chloride (PAC) (alumina content: 29%, dosage: 40 mg·L-1) was used as the coagulant, the removal efficiencies of algae, turbidity, total phosphorus, chlorophyll a, and COD in the eutrophic surface water reached 93.2±1.7%, 85.3±0.7%, 79.4±2.0%, 78.5±1.5% and 58.9±13.5%, respectively, after a flocculation time of 11.8 min, demonstrating the simultaneous effective removal of algae and phosphorus by the developed microbubble flotation device.
Process Optimization and Environmental Risk Assessment of Vermicomposting Co-composted from Sludge, Kitchen Waste and Stored Waste
WEI Qian-jia, ZHOU Ruo-xin, LI Na-ying, LI Hao, HAN Zhi-yong
2022, 38(10):  1354-1364.  doi:10.19741/j.issn.1673-4831.2021.0559
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The resource of sludge, kitchen waste and stock waste play an important role on the organic solid waste management in the city based on the waste classification. In this study, the process optimization and environmental risk assessment of vermicomposting co-composted from sludge, kitchen waste and stock waste (VCSKS) were studied by the orthogonal test, the plant growth experiment and potential ecological risk model. The results indicate that the VCSKS could significantly improve physical and chemical properties of composting and the growth of earthworms. However, the addition with more than 50% kitchen waste could restrain the growth and reproduction of earthworms. The best parameters of the VCSKS is 7∶3 mass ratio of sludge and kitchen waste, 5% addition of stock waste and 33 pieces per kilogram earthworms inoculation rate. Both the quality of vermicomposting and its mixed soil met with both the requirements of the organic fertilizer and the planting soil for greening. When the vermicomposting addition proportion was 20%, the growth of ryegrass was the best. When the vermicomposting addition proportion reached to 50%, the organic matter, total nitrogen, total phosphorus and available potassium were the largest, which increased to 107.00 g/kg, 6.69 mg/g, 5.96 mg/g and 0.42 mg/g, respectively. As the vermicomposting addition proportion increased from 0 to 50%, the potential ecological risk index of single heavy metal increased in soil, and the combined potential ecological risk factor increased from 17.42 to 33.82, with the environmental risk all to be at low ecological hazard level. Cu had the greatest potential ecological hazard (Er=17.69). With thirty times addition of vermicomposting at 20% proportion,of the fertilizer the ecological risk index of Cu could be increased from 10.69 to 35.04, and after then the accumulation effect would become non-obvious (Er=35.09). Therefore, vermicomposting co-composted from sludge, kitchen waste and stock waste will be a safe and effective route for the municipal organic solid waste management in cites.