Table of Content

25 February 2024, Volume 63 Issue 2

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Green and Low-carbon Development

Spatiotemporal pattern evolution and influencing factors of carbon emissions from arable land in the Yangtze River Economic Belt

LIU Xuan, SUN Yan, MA Jing, ZHANG Tian-wang, CHEN Fu

2024, 63(2):  1-7.  doi:10.14088/j.cnki.issn0439-8114.2024.02.001

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To clarify the green utilization of arable land, the IPCC carbon emission coefficient method was used to calculate the carbon emissions of arable land in 129 prefecture-level cities of the Yangtze River Economic Belt from 2000 to 2020. Spatial autocorrelation analysis was used to reveal the spatiotemporal evolution of arable land carbon emissions, and the LMDI model was used to decompose the contributions of various influencing factors. The results showed that from 2000 to 2020, the carbon emissions from arable land in the Yangtze River Economic Belt showed a downward trend over time, showing four stages, such as “maintaining stability—rapid growth—slow growth—slow decline”. In terms of space, there was a trend of high in the middle and east and low in the west, with significant global spatial autocorrelation. Local high-high clustering areas were distributed in the middle and lower reaches of the Yangtze River, low-high clustering areas were distributed in the middle reaches, and low-low clustering areas were mainly distributed in the upstream area. The promoting factor for agricultural carbon emissions within the region was the level of agricultural economy, while the inhibiting factor was mainly agricultural production efficiency, followed by agricultural production structure, and finally the scale of agricultural labor force. Therefore, there was a significant spatiotemporal difference in carbon emissions from arable land in the Yangtze River Economic Belt. Each region should develop carbon reduction strategies and land use control plans according to local conditions, improve agricultural production efficiency, optimize agricultural planting structure, strengthen regional linkage, and promote the coordinated development of low-carbon agriculture.

Spatial and temporal difference of carbon emission efficiency in Jiangsu Province based on super-efficiency SBM model

WANG Xiao-yue, DENG Jian-gao

2024, 63(2):  8-12，18.  doi:10.14088/j.cnki.issn0439-8114.2024.02.002

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Through the super-efficient SBM model with non-expected output and Malmquist productivity index, the carbon emission efficiency of each city in Jiangsu Province from 2011 to 2020 was calculated and the spatial and temporal differences were analyzed. Results showed that there was a significant difference in carbon emission efficiency among the prefecture-level cities in Jiangsu Province, with the overall characteristics of higher carbon emission efficiency in central Jiangsu than in southern Jiangsu and higher carbon emission efficiency in southern Jiangsu than in northern Jiangsu. The innovation of technology was the core driving factor for the improvement of carbon emission efficiency in Jiangsu Province. Unreasonable resource allocation and low scale efficiency were the main reasons why the carbon emission efficiency in Jiangsu Province had not reached the production frontier.

Research on agricultural carbon sink in Yunnan Province under the “Dual Carbon” strategy

WAN Si-qi, YUAN Yuan, FU Cheng-xiu, DONG Yun-feng, YAN Wen-guang, DONG Xiao-bo

2024, 63(2):  13-18.  doi:10.14088/j.cnki.issn0439-8114.2024.02.003

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The agricultural carbon emissions and carbon sinks in Yunnan Province from 2012 to 2021 were estimated, the results showed that, the carbon sink increased from 28.884 6 million tons in 2012 to 30.549 7 million tons in 2021, but the net carbon sink of agriculture decreased from 18.978 8 million tons in 2012 to 16.564 6 million tons in 2021. Among the agricultural carbon sources, the carbon emissions during the production process of agricultural land were the largest, accounting for 71.62% of carbon emissions in 2012 and rising to 74.19% in 2021. Research had found that carbon emissions from agricultural land production were continuously increasing, and the growth rate of crop carbon absorption was slower than carbon emissions, indicating that agricultural production methods were still a key improvement direction for low-carbon development. It was suggested that agricultural emission reduction technology should focus on innovative technological development in key directions such as planting, fertilization, and irrigation. At the same time, policy guidance should be tailored to local conditions, and resources should be linked to support technological, financial, and human factors, vigorously promoting agricultural emission reduction and carbon sink increase in Yunnan Province.

Carbon footprint of coffee production in Yunnan Province and its influencing factors

WANG Xin-hua, WANG Shuo

2024, 63(2):  19-24,78.  doi:10.14088/j.cnki.issn0439-8114.2024.02.004

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Taking Yunnan Province as the research area and coffee products as the research object, the carbon footprint of coffee production in Yunnan Province was calculated, the path analysis method to explore the influencing factors of carbon footprint in the coffee production process in Yunnan Province was used, the possibility of mitigating the carbon footprint was clarified, and suggestions for achieving water saving and emission reduction goals in the coffee production process were put forward, so as to provide a practical reference for better promoting the low-carbon and green development of the coffee industry in Yunnan Province.

Production Environment and Resources

The soil Cd and Pb risk threshold based on quality safety of Panax notoginseng

MENG Xi, LIANG She-wang, WU Han, LU Chun-wei, HE Zhong-jun

2024, 63(2):  25-30.  doi:10.14088/j.cnki.issn0439-8114.2024.02.005

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To ensure green planting and quality safety of Panax notoginseng, the soil risk threshold of Panax notoginseng safety production in China was discussed. Physicochemical properties of soil, content and available contents of Cd and Pb in soil, and contents of Cd and Pb in the main root of Panax notoginseng were analyzed. The relationship between Cd, Pb in the main root of Panax notoginseng and soil physical and chemical properties as well as total and available Cd, Pb in soil was analyzed by linear correlation analysis. The regression equation between total available Cd, Pb in soil and Cd, Pb in the main root of Panax notoginseng was established by the regression model, and the soil available Cd and Pb threshold was inversely estimated. The results showed that the over standard rates of Cd and Pb in soil samples were 83.64% and 16.36%, respectively. The soil Cd pollution was serious and the soil Pb was at a clean level. The Pb content in the main root of Panax notoginseng did not exceed the standard, and the exceeding rate of Cd content was 29.09%. Soil pH was negatively correlated with Pb in the main root of Panax notoginseng. There was a significant positive correlation and a extremely significant positive correlation between Cd in the main root of Panax notoginseng and the soil Cd content and the soil available Cd, respectively. Pb in the main root of Panax notoginseng was significantly positively correlated with Pb content and available Pb in soil. Based on the limitation standard of Cd and Pb in the main root of Panax notoginseng, the threshold value of soil available Cd and soil available Pb was 0.27 mg/kg and 70.66 mg/kg, respectively.

Improving effect of different amendments on coastal saline-alkali soil

WANG Li-yan, PAN Jie, ZHAO Jie, LI Meng-qi, ZHANG Hui, WANG Chun-shui, DONG Yu-chen, XIAO Hui

2024, 63(2):  31-35.  doi:10.14088/j.cnki.issn0439-8114.2024.02.006

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In order to study the improvement effect of different amendments on coastal soil, a pot experiment was conducted to study the effects of calcium sulfate, aluminium sulfate, ferric sulfate, ferrous sulfate and sulfur on soil total salt, pH and ion composition. The results showed that with the different amendments applied, the content of ions in the infiltration water varied greatly. In the first leaching, the contents of Na⁺ and Cl^- in the infiltration water treated with calcium sulfate, aluminum sulfate and ferric sulfate were 54.78% and 58.25%, 35.44% and 39.22%, 32.65% and 34.82% higher than those of CK, respectively, indicating that the addition of these three amendments had a better effect on soil salinity reduction, and calcium sulfate treatment had the best effect. In the second leaching, the Na⁺ content of ferric sulfate, calcium sulfate and aluminum sulfate treatment was 75.14%~347.76% higher than that of CK. Combined with two times of leaching, the results showed that calcium sulfate treatment had a more significant effect on the leaching of Na⁺ in soil. Compared with CK, the soil pH of each amendment treatment decreased to varying degrees, and the pH decreased by 2.23%~3.84%. Different amendments had different effects on soil ions. The contents of Ca²⁺ and Mg²⁺ in soil treated with amendments were higher than those of CK. Considering the effects of different amendments on soil pH, Na⁺ and Cl^-, it was suggested that ferric sulfate and calcium sulfate should be combined to improve coastal saline-alkali land.

Meta-analysis of soil nitrate nitrogen and nitrogen leaching under conventional agricultural management in Hetao Irrigation District, Inner Mongolia

YAN Jia-le, LAI Li-ming, DONG Rui-min, YANG Yang, WANG Hai-wei

2024, 63(2):  36-40，49.  doi:10.14088/j.cnki.issn0439-8114.2024.02.007

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In order to controll nitrogen fertilizer amount, save water, and improve soil fertility, soil nitrate nitrogen and nitrogen leaching and their related factors were systematically explored using meta-analysis methods in terms of the data collected from the published results in the Hetao Irrigation District, Inner Mongolia. The results showed that the means of nitrate nitrogen at the 0~20 cm depth in the corn, sunflower, and spring wheat fields under conventional management were 22.78, 9.92, and 17.80 mg/kg, the means of soil nitrogen leaching were 49.82, 45.11, and 93.73 kg/（hm²·a）, and the means of conventional nitrogen （N） application rate were 357.7, 233.2, and 320.0 kg/hm², respectively. The soil nitrogen leaching resulting from the conventional nitrogen application rate was 6.76 times that from the no nitrogen fertilizer application, and the main influencing factors were soil texture, soil surface organic matter, soil surface pH, crop tape, and irrigation rate. These findings indicated that the nitrogen application rate under the conventional management in the Hetao Irrigation District was high, the soil fertility tended to decrease over time, and the nitrogen leaching was serious.

Matching pattern of agricultural water and land resources in loess hilly areas from the perspective of water footprint：Taking Heshun County of Shanxi Province as an example

YAN Mei-xia, GUO Qing-xia, DING Yi, KANG Qing

2024, 63(2):  41-49.  doi:10.14088/j.cnki.issn0439-8114.2024.02.008

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From the perspective of water footprint, the spatial and temporal changes of production water footprint and cultivated land area of main crops in rural areas of Heshun County, Shanxi Province, from 2010 to 2019 were analyzed using CROPWAT and standard deviation ellipse model, the spatial-temporal matching pattern of agricultural water and land resources in rural areas in 2010,2014 and 2019 was studied using Gini coefficient and spatial mismatch index, and the direction of regulation was clarified. The results showed that, during the study period, Heshun County’s crop production water footprint, blue water footprint, green water footprint and cultivated land area all showed a downward trend. Green water footprint contributed the most to the total water footprint of crop production in all regions, and the proportion of green water footprint in crop production water footprint in all counties and townships was more than 62.0%. The spatial aggregation of crop production water footprint and arable land resources was increasing in western Heshun County, while the spatial mismatch between crop production water footprint, blue water footprint, green water footprint and arable land resources was increasing in Heshun County, the agricultural water and soil resources in the central and eastern regions of Heshun County were moderately mismatched and severely mismatched, respectively, which would be the key areas for agricultural water and land resources control in the future. Ten townships in the county could be divided into three control areas： water conservation and storage control areas, water and land optimization regulation control areas, and diversion water-saving irrigation control areas. In general, Heshun County’s agricultural water and land resources were out of balance due to social economy, input of production factors and climatic conditions, but were controlled artificially on the basis of the division of control zones, it could still achieve a greater improvement in the matching and coordination level of agricultural water and land resources.

Geochemical characteristics and occurrence forms of soil selenium in sorghum base of Maoba Town, Renhuai City

HUANG Xu-bin, PAN Zi-ping, SHAO Mao-yan, CHEN Ting

2024, 63(2):  50-54，66.  doi:10.14088/j.cnki.issn0439-8114.2024.02.009

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The organic sorghum base in Maoba Town of Renhuai City was taken as the research object to study the geochemical distribution and occurrence form characteristics of soil selenium. The results showed that soil selenium content in sorghum base ranged from 0.24 to 1.35 mg/kg, with an average of 0.50 mg/kg, which was 1.72 times of the national soil background value. Se-enriched soil was widely distributed in the study area, accounting for 50% of the total area. The main chemical forms of soil selenium were organic-sulfide bound and elemental selenium, accounting for 57.14%. The contents of Fe-Mn oxide bound selenium, exchangeable-carbonate bound selenium and residue selenium were not much different, accounting for 14.21%, 14.19% and 12.70%, respectively. The water-soluble selenium was the lowest （1.76%）. The sum of water-soluble selenium and exchangeable-carbonate bound selenium was relatively high （15.95%）, which indicated that the bioavailability of soil selenium was strong, and it was easy to be absorbed and utilized by plants, and was beneficial to the cultivation and production of Se-enriched crops. The content of total selenium and various forms of selenium in soil was positively correlated with organic matter, indicating that the increase of organic matter was beneficial to the accumulation of selenium in soil. Soil pH was significantly positively correlated with water-soluble selenium content, but weakly negatively correlated with total selenium and other forms of selenium content. It was confirmed that selenium mainly existed in the form of selenate under alkaline conditions, which improved the bioavailability of selenium. Therefore, the sorghum base in the study area had a high level of selenium enrichment, a large distribution area, and a strong bioavailability of selenium, which provided a good land resource condition for improving the quality of sorghum Hongyingzi,and developing local Se-enriched characteristic agricultural products.

Screening of maize stover degradation complex strains and fermentation to produce short-chain fatty acids

WANG Wen-jun, LIU Guo-qing, WANG Zhi-hua

2024, 63(2):  55-58.  doi:10.14088/j.cnki.issn0439-8114.2024.02.010

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The compound strains obtained by screening were used to ferment corn straw, the effects of the compound strains on degrading straw to produce short-chain fatty acids were studied, and the structural composition of the microbial consortium was analyzed. The results showed that the degradation rate of the compound strain was the fastest in the first 4 days. The degradation rates of straw, cellulose and lignin reached 30.35%, 27.07% and 14.71%, respectively. At 12 days, the degradation rates reached 40.02%, 32.25% and 20.93%, respectively. The metabolites of the compound strain were isobutyric acid and acetic acid, which accounted for 36.46% and 33.15% of the total short chain fatty acids, respectively. According to high-throughput sequencing, the dominant bacteria genera in the compound strains were mainly composed of Clostridium sensu stricto, Cellulosilyticum, Clostridium XIVa, Enterobacteriaceae and Peptostreptococcaceae.

Major food crops extraction from GF-6 WFV multispectral imagery based on feature optimization

XU Kang, HUANG Bing-xin, WANG Peng-fei

2024, 63(2):  59-66.  doi:10.14088/j.cnki.issn0439-8114.2024.02.011

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In view of the characteristics of multiple red edge bands of GF-6 wide field view （WFV） multispectral imagery, a method for extracting major food crops from GF-6 WFV image based on feature optimization was proposed. Firstly, characteristic variables, including spectral feature, vegetation index, water index and red edge index, were extracted from preprocessed GF-6 WFV image. Then, the optimal feature set was generated by using a recursive feature elimination algorithm with permutation importance. Finally, machine learning methods and the optimal feature combination were utilized to extract major food crops. Taking Rudong County, Jiangsu Province as the study area, six experiments were used to extract grain crops, and the effects of different characteristics and different classification models on the extraction accuracy of wheat, rice and corn were discussed. The results indicated that the GF-6 WFV image was suitable for extracting major food crops, and the two red-edge bands and red edge indexes of GF-6 WFV data played an important role in distinguishing three main food crops and other objects. Among the six experiments, the overall accuracy of the classification result based on the optimal feature combination and XGBoost algorithm was the highest, improving 3.08 and 5.58 percentage point respectively compared with the classification result without using red edge bands and indexes.

Collection and phenotypic diversity evaluation of local Astragalus sinicus L. germplasm resources in Guangxi

WEI Cai-hui, DONG Wen-bin, LI Zhong-yi, TANG Hong-qin, ZENG Cheng-cheng, MO Yong-cheng, HE Tie-guang

2024, 63(2):  67-73.  doi:10.14088/j.cnki.issn0439-8114.2024.02.012

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Taking the opportunity of the “Third National Crop Germplasm Resources Census and Collection Action” of the Ministry of Agriculture and Rural Affairs, the investigation, collection, evaluation and identification of Astragalus chinensis L. germplasm resources in Guangxi were carried out. The results showed that the 58 collected local resources were mainly distributed in the middle and low altitude areas of 0~400 meters in northeastern Guangxi. Phenotypic analysis of 12 agronomic traits showed rich genetic diversity. Principal component analysis divided 12 agronomic traits into 3 principal components, namely seed yield, biological yield, and growth period characteristics, with a cumulative contribution rate of 72.089%. By weighted average calculation, the top 10 germplasm resources in the comprehensive ranking were GXLF20180011, GXLF2019109, GXLF2019156, GXLF2019118, GXLF2019112, GXLF2019117, GXLF20180006, GXLF2019125, GXLF2019111, and GXLF2019136. The total growth period of the top 10 germplasm resources was 134~147 d, with stem diameter of 2.83~3.66 mm during the peak flowering period, branch length of 41.63~54.73 cm during the peak flowering period, branch number per plant of 2.83~4.19, flower number per branch of 5.85~6.99, total flower number of 17.55~26.23 per plant, pod bearing flower number of 14.33~19.97 per plant, and fresh grass yield of 10 458.15~48 792.75 kg/hm², hay yield of 1 037.36~5 724.34 kg/hm², and seed yield of 246.75~991.20 kg/hm².

Effect of special fertilizer for oilseed rape in Central Hubei Province

GU He-he, FANG Wen, CHEN Jin, LI Xu-chun, LIAO Shi-peng, YANG Yu-xiong, REN Tao, LU Jian-wei

2024, 63(2):  74-78.  doi:10.14088/j.cnki.issn0439-8114.2024.02.013

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To clarify the effect of special fertilizers for oilseed rape （Brassica napus L.） on the yield enhancement of direct seeding oilseed rape in central Hubei Province, field experiments for two consecutive years in Shayang County, Hubei Province from 2019 to 2021 were carried out, with four fertilization treatments of no fertilizer, conventional fertilizer, Yishizhuang special fertilizer and Yangfeng special fertilizer, and the differences of the yield, aboveground biomass, aboveground nutrient content, aboveground nutrient accumulation and fertilizer partial productivity of oilseed rape at mature stage under four treatments were analyzed. The results showed that compared with no fertilization control, both conventional fertilization and special fertilizer treatments could significantly increase rapeseed yield. Compared with the conventional fertilization, the total nutrient input of the special fertilizer treatments decreased by 41.3%, but there was no significant difference in rapeseed yield between conventional fertilization and special fertilizer treatments. Fertilizer application significantly increased the aboveground biomass of oilseed rape and promoted the absorption of nutrients by the aboveground oilseed rape. The treatment with special fertilizer for oilseed rape significantly improved the partial productivity of fertilizers. Compared with the conventional fertilization treatment, the average fertilizer partial productivity of Yishizhuang special fertilizer treatment and Yangfeng special fertilizer treatment increased by 80.6% and 68.2% respectively in 2019—2020 and 2020—2021. In conclusion, the special fertilizer for oilseed rape improved the utilization rate of fertilizer while ensuring a high and stable yield of oilseed rape.

Changes of yield and quality of cigar tobacco leaves and soil available nutrients content by replacing chemical fertilizer with rapeseed cake fertilizer at equal amount of nitrogen

LI Fu-qiang, LIAO Cheng, CHEN Hong-hua, QIAO Bao-ming, XIANG Zhe-di, WANG Xue-song, XU Xiang-yu, TAN Jun

2024, 63(2):  79-83.  doi:10.14088/j.cnki.issn0439-8114.2024.02.014

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In order to explore the effects of application of different proportions of organic fertilizer nitrogen on the growth and quality of cigar tobacco leaves, a field experiment was conducted, with cigar tobacco variety CX80 as the material and rapeseed cake fertilizer as the source of organic fertilizer nitrogen, and four treatments were set according to different proportions of organic fertilizer nitrogen and chemical fertilizer nitrogen, including CK （0∶10%）, T1 （10%∶90%）, T2 （20%∶80%） and T3 （30%∶70%）. The effects of each treatment on pH and nutrient content of soil, and growth and quality of tobacco leaves were studied. The results showed that, with the increase of the replacement ratio of organic nitrogen, the content of soil available potassium, alkali-hydrolyzed nitrogen and available boron gradually decreased, the available molybdenum continued to increase, and the pH value, organic matter, exchangeable calcium, exchangeable magnesium and cation exchange capacity increased first and then decreased. Compared with the control, the plant height and leaf number of T2 increased by 12.02% and 3.09%, respectively, and the maximum leaf area of T3 increased by 7.69%. The yield of treatment T2 and T3 was significantly higher than CK, and the average price of tobacco leaves was increased by 7.64% and 7.57% compared with CK. With the increase of the proportion of organic fertilizer nitrogen replacing chemical fertilizer nitrogen, the contents of nicotine, total sugar and total nitrogen in tobacco leaves after air-curing increased first and then decreased, and the ratio of sugar to alkali and the ratio of potassium to chloride increased. The sensory taste showed a fluctuating trend, and T3 was the highest, followed by T1 and T2.

Controlled-release fertilizer combined with nutrient synergist significantly increased tomato yield and quality

SUN Ming, XIE Huan-huan, LIU De-rui, LYU Chen-hao, ZHAO Zhu-qing, LIU Yao, CHEN E, CHEN Yong-bo

2024, 63(2):  84-87，93.  doi:10.14088/j.cnki.issn0439-8114.2024.02.015

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The effects of controlled-release fertilizer combined with nutrient synergist on the growth, yield and quality of the tomato were studied by field experiments with the tomato（Lycopersicon esculentum Mill.） variety Ruifei as the experimental material. The results showed that the combination of controlled-release fertilizer and nutrient synergist could significantly increase stem diameter（P<0.05）. Compared with conventional fertilization,controlled-release fertilizer and controlled-release fertilizer combined with nutrient synergist could significantly improve tomato quality, the soluble solids content of tomato fruit had an increasing trend, the soluble sugar content and vitamin C content were significantly increased （P<0.05）, and the color and hardness of tomato fruit were also improved. Compared with conventional fertilization, controlled-release fertilizer and controlled-release fertilizer combined with nutrient synergist could effectively improve tomato yield and economic benefits, the yield increased by 12.7% and 29.2%, respectively, and the net profit increased by 36 500 yuan/hm² and 77 200 yuan/hm², respectively. In conclusion, controlled-release fertilizer combined with nutrient synergists could increase tomato yield and efficiency, and had important practical value in achieving light and simplified production.

Characteristics of microbial quantity and enzyme activity in tobacco planting soil under application of mixed seeding green manure

CHEN Wei, CHEN Yi, JIANG Chao-ying, YANG Quan-liu, LU Xian-ren, JIANG Wei

2024, 63(2):  88-93.  doi:10.14088/j.cnki.issn0439-8114.2024.02.016

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In order to study effects of the mixed seeding green manure application on the microbial count and enzyme activity of tobacco planting soil, a site-specific field experiment was conducted by performing no green manure（control）, Lolium perenne monocropping, Vicia villosa var. glabrescens monocropping, and Lolium perenne and Vicia villosa var. glabrescens mixture （application of mixed seeding green manure）. The microbial quantity and enzyme activities of soil were analyzed after the consecutive 2-year test. The results indicated that the total number of bacteria and nitrifying bacteria in soil under application of mixed green manure were 2.25~3.62 times and 1.60~3.11 times as the control, 1.31~1.76 times and 1.43~2.92 times as Lolium perenne monocropping, 1.25~1.88 times and 1.08~1.27 times as Vicia villosa var. glabrescens monocropping. The numbers of actinomyces and fungi in soil under application of mixed green manure were 1.13~2.00 times and 1.02~1.93 times as green manure monocropping at the early stage of the tobacco planting field, respectively, and lower than those of the green manure monocropping at the later stage of the tobacco planting field. There was no significant difference in the number of ammonifying bacteria in the soil among the treatments at the middle and later stage of the tobacco planting field. The activities of soil catalase, sucrase, urease, acid phosphatase and cellulase in the soil under application of the mixed green manure at different growth stages were significantly higher than those of the control, and also higher than those of Lolium perenne monocropping and Vicia villosa var. glabrescens monocropping. It could be seen that mixed seeding green manure application was beneficial to improve the micro-ecological environment of tobacco planting soil and could be used as a technical model for tobacco planting soil conservation.

Land Use and Transformation

Spatiotemporal differentiation and formation mechanism of arable land function transformation in China

XIONG Qiang, ZHENG Liang, JIANG Jin-hui

2024, 63(2):  94-100，110.  doi:10.14088/j.cnki.issn0439-8114.2024.02.017

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In order to accurately describe the path and formation mechanism of farmland function transformation in China, the theoretical framework and evaluation index system of farmland function transformation were established, and the method of determining index weight based on game theory was proposed. Based on the comprehensive index model, the farmland functional transformation index of China’s provinces from 2000 to 2020 was measured, and the mechanism of farmland transformation in China was analyzed. The results showed that from 2000 to 2020, the social function of cultivated land increased and then decreased, the economic function decreased and then increased, and the ecological function remained stable. Among the sub-functions, the function of food security and ecological function were in the main position, the economic contribution function of cultivated land was stronger in underdeveloped areas, and the social function of cultivated land was stronger in northeast areas. From 2000 to 2020, the change of cultivated land function in China took a turning trend and began to evolve along the development direction of urban and rural residents’ demand. On the whole, the driving force of the urbanization level, the quality of economic development, the proportion of non-agricultural industry and the difference in the central, eastern and western areas on cultivated land function transformation had reduced, the driving force of regional economic aggregate on cultivated land function had increased, and the influence of population density on cultivated land function had remained stable.

Analysis on the characteristics and influencing factors of urban land use expansion in Nanjing metropolitan area

XIONG Yuan-yuan, LI Yi

2024, 63(2):  101-110.  doi:10.14088/j.cnki.issn0439-8114.2024.02.018

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Taking Nanjing metropolitan area as the research object, based on the land use data extracted from the 5 remote sensing images from 2000 to 2020, the temporal and spatial characteristics and influencing factors of urban land use expansion in the urban agglomeration of Nanjing metropolitan area were quantitatively analyzed from the expansion intensity, difference index of expansion intensity, cluster analysis, landscape pattern index and multiple regression model. The results showed that based on the analysis of the expansion intensity index, the urban land area of Nanjing metropolitan area continued to increase from 2000 to 2020, and the expansion intensity showed a trend of “rising-falling-rising”, and the expansion intensity of urban land was the highest from 2015 to 2020. Based on the analysis of the difference index of urban land expansion intensity, the high-speed expansion area of Nanjing metropolitan area was concentrated in the border areas of the metropolitan area, mainly distributed in the northeast and southwest directions, and the urban land expansion layout was developing towards a balanced development. Based on the analysis of the cluster analysis model, it was found that the urban land use expansion in Nanjing metropolitan area was randomly distributed from 2000 to 2010, the urban land use expansion was concentrated at high values from 2010 to 2015, and the land use expansion was randomly distributed from 2015 to 2020. Based on the analysis of the landscape pattern index, it was found that the degree of urban land expansion agglomeration in Nanjing metropolitan area gradually increased, the distribution of patches became more and more concentrated, the shape of patches tended to be complicated in the continuous integration and expansion, the traffic connection degree in urban land patches continued to increase, and the expansion of urban land in Nanjing metropolitan area developed towards synergy. Based on the analysis of the multiple regression model, population growth, urban economic development and transportation construction were the main factors promoting the expansion of urban land.

Analysis on the spatiotemporal characteristics and driving factors of land use transition in Jinzhong based on “production-living-ecological” functions

MA Xin, WANG Jin, LIU Hui-fang, GUO Yong-long, HAN Miao, WANG Dao-yuan

2024, 63(2):  111-119，127.  doi:10.14088/j.cnki.issn0439-8114.2024.02.019

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The characteristics of land use transition and its driving factors in Jinzhong City, Shanxi Province from the perspective of the “Production-Living-Ecological” functions were quantitatively analyzed, to explore the laws of land use transition in the city were explored. The geo-information atlas and multi-indicator comprehensive index methods were used to explore the geographic features of land use transition and the spatial-temporal patterns features of recessive forms in Jinzhong City from 2000 to 2020, and the geodetector was used to analyze the drivers of transition. The results showed that during the study period, Jinzhong City was in a state of high-intensity land use transition, and the most significant change in atlas units from 2000 to 2010 was the conversion of agricultural production land to greenland ecological land and rural living land. From 2010 to 2020, the main type of atlas unit was the conversion between agricultural production land and greenland ecological land. The transition index of all districts and counties in Jinzhong City showed a continuous upward trend, forming a “Z” shaped spatial agglomeration in the northeastern part of Jinzhong in 2020. Yuci District, Pingyao County, and its surrounding Shouyang County, Taigu District, Qi County, and Yushe County together formed a “T”shaped high-speed development area. The transition of land use was the result of the combined effects of the natural environment, transport location, and social economy. The natural environment and transportation location had a greater driving force for the explicit transition of land use, while transportation location and socio-economic factors had a greater driving force for the recessive transition.

Land use transformation and ecological environment effects of “production-living-ecological spaces” in Changsha-Zhuzhou-Xiangtan Metropolitan Area

ZHANG Rong, MAO De-hua

2024, 63(2):  120-127.  doi:10.14088/j.cnki.issn0439-8114.2024.02.020

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Based on the construction of the land type division system of “production-living-ecological spaces”, comprehensively using the methods of land transfer matrix, ecological environment quality index and ecological contribution rate of land use transformation, the characteristics and ecological environmental effects of “production-living-ecological spaces” land transformation in Changsha-Zhuzhou-Xiangtan Metropolitan Area were quantitatively analyzed from 2000 to 2020. The results showed that from 2000 to 2020, the ecological land was the main land type in the “production-living-ecological spaces” land in Changsha-Zhuzhou-Xiangtan Metropolitan Area, and the dynamic changes of the quantity of living land and production land were large; from the perspective of the “production-living-ecological spaces” land use transformation structure, the agricultural production land and forest land ecological land were mainly transformed into each other, and a large number of agricultural production land and forest land ecological land were transformed into industrial and mining production land and urban living land; the ecological environment quality of the Changsha-Zhuzhou-Xiangtan Metropolitan Area showed a gradual decline trend, and the deterioration was the most prominent from 2005 to 2010. During the study period, low-quality areas and lower quality areas continued to expand; the main factors affecting the change of ecological environment were the conversion of agricultural production land and forest ecological land and the external expansion of urban living land and industrial and mining production land, which occupied a large amount of forest ecological land.

The spatial and temporal change of land use in Nanning from 1990 to 2020

LUO Yuan-jia, LIANG Qing-xuan, LIU Hong, LIAO Dong-ping, LI Yue-lian

2024, 63(2):  128-136.  doi:10.14088/j.cnki.issn0439-8114.2024.02.021

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In order to reveal the spatio-temporal changes of land use in Nanning City, the spatial-temporal evolution characteristics of land use in Nanning City from 1990 to 2020 were analyzed in depth by using geographic information system （GIS） technology and methods such as land use dynamics, degree of utilization and transfer matrix. The results showed that from 1990 to 2020, the changes of land use types in Nanning City were obvious, the overall speed of land use change was accelerated, the construction land and unutilized land increased and showed a growth rate, and the cultivated land, forest land, grassland and water area decreased and showed deceleration; the degree of land use in Nanning City was at a medium level, with the continuous disturbance and influence of human activities on the land, the level of land use degree showed a gradually increasing trend; during the 30 years, a total of 1 051.61 km² of land use types in Nanning City had been transferred, of which the construction land and unutilized land showed a net transfer in, and the cultivated land, forest land, grassland and water area showed a net transfer out.

Changes of land use and ecosystem services value in Xunwu County from 1990 to 2020

CHEN Xiao-jie, WANG Yuan-dong, MING Lei, MENG Li-hong

2024, 63(2):  137-141,147.  doi:10.14088/j.cnki.issn0439-8114.2024.02.022

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It was of great significance to explore the characteristics of land use change in Xunwu County, Ganzhou City, Hubei Province, and its impact on ecosystem services value （ESV） in the long-term series to ensure the ecological security and improve the regional ecological environment in the Dongjiang Basin. Based on the land cover data from 1990 to 2020, the change of land use in Xunwu County during this period was analyzed, and the ecosystem service value of Xunwu County was evaluated by using the equivalent factor method. The results showed that the main land use types in Xunwu County were forest land, followed by cultivated land, and the proportion of the two land use types in the total area of Xunwu County was more than 98.0%. From 1990 to 2020, the total area of forest land and grassland in Xunwu County showed a downward trend, the proportion of cultivated land increased year by year, and the area of farmland returned to forest and grassland was less than the area of cultivated land reclamation. From 1990 to 2020, the ecosystem service value of Xunwu County showed a downward trend, and the areas with low ESV values were mainly distributed in the southwest and central parts of the study area, while the areas with high ESV values were consistent with the distribution of forest land in the study area.

Land use change analysis of Tianshan wild fruit forest distribution area based on GEE

DING Ji-da, PU Zhi, LU Wen-rui, WEN Zhao-fa

2024, 63(2):  142-147.  doi:10.14088/j.cnki.issn0439-8114.2024.02.023

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Based on Google earth engine （GEE） remote sensing big data cloud platform, through Landsat series images, using random forest algorithm, combined with spectral index, topographic features for land use classification, through the geographic information mapping, and the spatial and temporal changes of land use of Tianshan wild fruit forest distribution area from 1997 to 2021 were analyzed through geographic information mapping and land use dynamics. The results showed that through GEE platform and random forest algorithm, land use classification could be realized quickly, and the overall classification accuracy was greater than 90.00%, and the Kappa coefficient was higher than 0.85; from 1997 to 2021, the Tianshan wild fruit forest distribution area was mainly arable land, forest land and grassland, and the three accounted for more than 90% of the total area; land use changes were dominated by the transformation of grassland to arable land and the transformation of forest land to grassland; construction land, arable land and water area continued to increase, the change showed the aggregative distribution, forest land decreased first and then increased, and the overall land area decreased seriously; the growth rate of construction land was the largest and the change was the most drastic, the overall reduction rate of unused land and forest land was large and the change was more drastic.

Ecological Environment and Governance

Ecological restoration zoning of cultivated land in Tacheng City based on soil quality and landscape pattern

LEI Hai-feng, WANG Xi-yuan, GAO Hai-feng

2024, 63(2):  148-155.  doi:10.14088/j.cnki.issn0439-8114.2024.02.024

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Taking Tacheng City, Xinjiang as the research object, an evaluation index system was constructed from the perspective of soil quality and landscape pattern to evaluate the soil quality and landscape pattern of cultivated land. The results showed that the soil quality of cultivated land in Tacheng City was divided into four levels. Grade I cultivated land accounted for 9.95%, Grade II cultivated land accounted for 27.99%, Grade III cultivated land accounted for 37.04%, and Grade IV cultivated land accounted for 25.02%. Grade I cultivated land could be used as a selection object for high standard cultivated land construction, while Grade IV cultivated land was not suitable for development and required soil remediation;the landscape pattern of cultivated land in Tacheng City was divided into four levels. Grade I cultivated land accounted for 34.6%, Grade II cultivated land accounted for 40.1%, Grade III cultivated land accounted for 21.6%, and Grade IV cultivated land accounted for 3.7%; based on the soil quality and landscape pattern, the ecological restoration areas of cultivated land in Tacheng City were divided into 6 categories： 218 km² of high-quality protection area, 279 km² of soil quality improvement area, 196 km² of soil quality restoration area, 192 km² of landscape pattern improvement area, 58 km² of landscape pattern restoration area, and 70 km² of farmland restoration area. Overall, the key direction for ecological restoration of cultivated land in Tacheng City was soil quality improvement and restoration.

The soil erosion evaluation based on RUSLE Model： A case study of Liuhe District, Nanjing City

LYU Han, XU Li-ping, CHEN Qi-jun

2024, 63(2):  156-161,239.  doi:10.14088/j.cnki.issn0439-8114.2024.02.025

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Taking Chengqiao Street, Liuhe District, Nanjing City, Jiangsu Province, as the research area, the evaluation process of soil erosion intensity in the research area was studied by combining theoretical algorithm, model building and field application according to the relevant standards of the Ministry of Water Resources. The existing DEM generation method and land use classification method were optimized to some extent, and the monitoring elements of soil erosion were extracted by using multi-source remote sensing impact data, and the soil erosion intensity in the study area was estimated based on the RUSLE model. The results of practical application in the field were compared and analyzed with the existing methods to verify the validity and objectivity of the theories and algorithms.

Evaluation and prediction of land ecological security based on DPSIR and GM（1,1） model：Taking Luoyang City, Henan Province as an example

ZHANG Yao, LI Shuai, WANG Peng-fei

2024, 63(2):  162-169.  doi:10.14088/j.cnki.issn0439-8114.2024.02.026

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In order to explore the current situation and main influencing factors of land ecological security in Luoyang City, based on the DPSIR model, 24 evaluation indicators were selected to construct an evaluation indicator system. The entropy weight method, obstacle degree model （ODM）, and grey system GM（1,1） model were used to evaluate and predict the land ecological security situation in Luoyang City from 2010 to 2020. The results showed that the land ecological security in Luoyang City showed an upward trend from 2010 to 2020, with relatively small fluctuations from 2010 to 2017. In 2018, the land ecological security index increased significantly, from 0.480 5 to 0.602 7;in 2020, the level of land ecological security increased from a critical safety level to a relatively safe level, with factors such as natural population growth rate, pesticide consumption per unit of arable land, per capita park green space area, and the proportion of tertiary industry output being important driving forces for the index’s increase;the subsystem with the highest weight was the response subsystem, and the single indicator with the highest weight was the per capita park green space area; the indicator with the highest frequency of occurrence among obstacle factors was the harmless treatment rate of household waste;according to the prediction results of the grey system GM（1,1） model, the land ecological security level in Luoyang City would reach the safety level in 2023.

Evaluation and mechanism on the importance of ecosystem service functions in Yuxi City

DU Yuan-yuan, LIU Shi-xin, TAN Mei-xian, XIANG Dong-lei, CHEN Yun-chun

2024, 63(2):  170-177,188.  doi:10.14088/j.cnki.issn0439-8114.2024.02.027

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Taking Yuxi City as the research object, combined with the actual situation and data of its ecological environment, this paper evaluated the importance of ecosystem service functions in Yuxi City and explored the internal mechanism of its importance pattern formation.The results showed that the importance of ecosystem service functions in Yuxi City was mainly extremely important, with an area of 13 556.94 km², accounting for 90.74% of the total area of Yuxi City; the distribution of general important areas was relatively small, located in the southwest of Yuxi City, mainly in Yuanjiang County;the distribution of important areas was relatively scattered, mostly in the eastern part of Yuxi City, mainly distributed in Hongta District, Jiangchuan District, Haitong County, and Chengjiang City;the extremely important areas were widely distributed, covering various counties and districts in Yuxi City, mainly distributed in Eshan County, Yimen County, Xinping County, and Huaning County;among different importance levels, the total area of cultivated land and forest land accounted for a relatively large proportion. The proportion of cultivated land area was negatively correlated with the importance level of ecosystem service functions, while the proportion of forest land area was positively correlated with the importance level of ecosystem service functions. As the importance level changed, the two showed a pattern of one declining and the other growing.

The spatiotemporal variation characteristics of grassland vegetation coverage and grassland degradation in northern Xinjiang from 2000 to 2020

FAN Jun, YAN An, LI Jing-yan, LU Qian-cheng, SUN Meng

2024, 63(2):  178-188.  doi:10.14088/j.cnki.issn0439-8114.2024.02.028

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Using Landsat NDVI sequence data from 2000 to 2020 as the data source, this paper used spatiotemporal and statistical analysis methods to explore the spatiotemporal variation characteristics of grassland vegetation coverage and grassland degradation in northern Xinjiang. The driving forces of grassland degradation in Northern Xinjiang were analyzed from two aspects： climate and human activities. The results showed that from the spatiotemporal changes of grassland vegetation coverage, the overall trend of grassland vegetation coverage in Northern Xinjiang from 2000 to 2020 was increasing;the ecosystem in the Northern part of Xinjiang was more fragile and susceptible to the impacts of climate change and human activities;the grassland in the Northern Xinjiang region had a relatively high grassland vegetation coverage on the sunny slope. The areas with a high grassland vegetation coverage were mainly located in mountainous areas with high terrain index and relatively good water and thermal conditions. The areas with a low grassland vegetation coverage were mainly located in areas such as relatively water scarce and arid desert edges. From the spatiotemporal variation characteristics of grassland degradation, there was a significant shift in the levels of grassland degradation in Northern Xinjiang from 2000 to 2020, mainly manifested as the transition from mild and moderate degradation to non degraded grassland, and from severe degradation to mild degradation, indicating that the phenomenon of grassland degradation in Northern Xinjiang had further improved. Grassland degradation in Northern Xinjiang was the result of the combined effects of climate change and human activities, with precipitation being the main climate factor.

The Temporal and spatial evolution and prediction of ecosystem service value in Yuxi City based on the FLUS-Markov model

LIU Shi-xin, LI Jian-hua, SUN Yong-qi, DU Yuan-yuan, XIANG Dong-lei, CHEN Yun-chun

2024, 63(2):  189-198.  doi:10.14088/j.cnki.issn0439-8114.2024.02.029

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Based on the ecological landscape type data of Yuxi City in 2010 and 2020, and the economic value correction ecosystem service value coefficient of grain production,analyzed the ecological landscape types and distribution characteristics of ecosystem service value in Yuxi City were analyzed, and the FLUS-Markov model was used to predict the ecosystem service value and its distribution in Yuxi City by 2030.The results showed that the Kappa coefficient of the predicted results of the model had been increased to 0.896 9, with an overall accuracy of 0.939 3, indicating high accuracy;from 2010 to 2020, the area of forest and grassland in Yuxi City showed a decreasing trend, and the ecosystem mainly composed of forest, grassland, and water still faced threats; the ecosystem service value of Yuxi City was 53.504 71 billion yuan, with a change rate of -0.129 7% in 2030. Yuxi City should strengthen the protection of forest and grassland, strengthen the implementation of policies for returning farmland to forest and grassland, and reasonably control the conversion of grassland and forest land to arable land;the ecosystem service value of Yuxi City showed still as follows： west>center>east in 2030;the contribution rates of ecosystem service value from high to low were Xinping County, Yuanjiang County, Eshan County, Yimen County, Huaning County, Hongta District, Jiangchuan District, Chengjiang City, and Tonghai County in various counties and districts of Yuxi City in 2030.

Analysis of built-up area range and ecological quality changes in the Erhai Basin based on Google Earth Engine

ZHENG Shu-yuan, CHEN Xing-yu, HAI Yan, WANG Jian-xiong

2024, 63(2):  199-204.  doi:10.14088/j.cnki.issn0439-8114.2024.02.030

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Taking Erhai Basin as the research area, with the help of Google Earth Engine cloud platform and Landsat 8 OLI series images, the enhanced index-based build-up index （EIBI） of the research area was synthesized and the built-up areas in Erhai Basin was extracted. Then, the remote sensing-based ecological index of the study area was synthesized. Through the spatial correlation analysis of the remote sensing-based ecological index of the built-up area and the basin, the ecological assessment of Erhai Basin and its built-up area from 2014 to 2021 was carried out. The results showed that the EIBI could effectively enhance the building information. Using EIBI could effectively and accurately extract the built-up area of the study area. After EIBI extraction, the expansion area of the built-up area of Erhai Basin from 2014 to 2021 was 14.712 km². From 2014 to 2021, the ecology of Erhai Basin was significantly improved, the remote sensing ecological index increased by 0.008, with an increase rate of 0.001/year, and more than 65% of the regional ecology in the basin was improved. The built-up area in Erhai Basin roughly matched the area where the ecology had not been improved. The ecological quality of the built-up area had not been significantly improved after ecological restoration, and the ecological quality of the built-up area showed a downward trend year by year, indicating that the built-up area had resistance to environmental improvement.

Spatiotemporal variation analysis of vegetation index in water source region of the middle route of South-to-North Water Diversion Project

BAI Jing-feng, ZHANG Hai-jun, BAI Yun-fan

2024, 63(2):  205-210.  doi:10.14088/j.cnki.issn0439-8114.2024.02.031

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The single linear regression （SLOPE） and geographically weighted regression （GWR） methods were used to study the variation trend and mechanism of vegetation distribution in the water source area of the middle route of the South-to-North Water Diversion Project by vegetation index （NDVI）, so as to provide theoretical support for guaranteeing water quantity and quality. The result showed that the NDVI and the inflow runoff increased synchronously in the water source area from 2000 to 2019. Vegetation gradually became better. The NDVI increase rate was large before 2007, but fluctuated from 2008 to 2011, and decreased after 2012. The NDVI changed obviously in the northeast, west and around the Danjiangkou reservoir area,these areas had low and flat terrain and concentrated population. The NDVI changed little in middle and high mountain areas. The elevation, slope, population and urbanization were the main factors affecting NDVI distribution in the water source region, while precipitation, temperature and industrial proportion were the secondary factors. The intensity and direction of the influencing factors had obvious heterogeneity. The most significant range affected by natural geographical factors on NDVI were the areas with elevation below 1 090 m and average annual precipitation above 980 mm. The significant range affected by human geographical factors were the areas with high population density and high urbanization rate.

Spatiotemporal distribution and centre of gravity dynamic change of wild fruit forests in Emin County, Xinjiang from 2007 to 2020

HU Xin-yue, SUN Qian, HUANG Jin-yi, SONG Ting-wei, GUO Zheng-yu

2024, 63(2):  211-218.  doi:10.14088/j.cnki.issn0439-8114.2024.02.032

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Taking the distribution area of wild fruit forests in Emin County as the research area, using the remote sensing images of Quick bird in 2007 and Gaofen-1 satellite in 2013 and 2020, and the wild fruit forests field measurement data, the information interpretation and area extraction of wild fruit forests were realized, and based on the dynamic degree model, transfer matrix model and center of gravity migration model, the temporal and spatial distribution characteristics and dynamic changes of wild fruit forests in the study area from 2007 to 2020 were analyzed, and the mutual conversion between various features and wild fruit forests was mastered. The shift of the center of gravity of the spatial distribution of wild fruit forests was analyzed, and the reasons affecting the temporal and spatial distribution of wild fruit forests in the study area were discussed. The results showed that the area of wild fruit forests increased by 3.91 km² from 2007 to 2020, which showed a continuous and slow increasing trend, and the development of tourist attractions directly led to the increase of building land area; in the past 14 years, the area of wild fruit foresst increased gradually, which was attributed to the frequent conversion of grassland and bare soil to wild fruit forests, and the transformation of grassland to wild fruit forests was the most significant; the change range of the center of gravity of wild fruit forests was small, and the spatial distribution was relatively stable.

Microbial characteristics of tailwater from rural domestic sewage treatment facilities in subsurface constructed wetlands

CHEN Shu-ping, LU Yuan, ZHANG Wen-yi, LI Qiao, WU Ke, WU Jin-hai, JIN Lin-fei

2024, 63(2):  219-223.  doi:10.14088/j.cnki.issn0439-8114.2024.02.033

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Rural domestic sewage was treated by A1/O1/A2/O2 facilities and flowed into the subsurface constructed wetland （abbreviated as constructed wetland）. To reveal its biodegradation characteristics, the microbial characteristics of constructed wetland were analyzed through urease activity and microbial amplicon sequencing. The results showed that the urease activity at the inlet of the constructed wetland was higher than that at the outlet. The urease activity at the outlet was significantly positively correlated with the total nitrogen removal rate. The higher the urease activity at the outlet, the better the total nitrogen removal effect;microbial amplicon sequencing showed that the dominant bacterial phyla in constructed wetland were Proteobacteria, Bacteroidetes, and Firmicutes. The relative abundance of Proteobacteria and Bacteroidetes decreased by 8.41 percentage points and 12.14 percentage points respectively from the inlet to the outlet, while Firmicutes increased by 12.91 percentage points; the content of denitrifying bacteria in the inlet and outlet of the constructed wetland was relatively high, with relative abundances of 20.51% and 14.18%, respectively. Among them, the bacteria with heterotrophic nitrification and denitrification functions were also relatively abundant, with 8.54% and 7.44%, respectively.

The temporal and spatial characteristics and pollution source of agricultural non-point source pollution in Shaanxi Province

MENG Xiao-jun, WANG Xin-jie, ZHU Ni, GE Guang-huan

2024, 63(2):  224-231.  doi:10.14088/j.cnki.issn0439-8114.2024.02.034

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In order to clarify the spatiotemporal characteristics, key pollution sources, pollution areas, and pollution types of the agricultural non-point source pollution in Shaanxi Province, the export coefficient method （ECM） was used to estimate the pollution load of total nitrogen （TN） and total phosphorus （TP） in 11 urban areas of Shaanxi Province from 2010 to 2019, and the equal standard pollution load method was adopted to evaluate the pollution sources. The 11 urban areas were divided into agricultural non-point source pollution types using the rapid clustering method.The results showed that from 2010 to 2019, the agricultural non-point source pollution TN and TP pollution load in Shaanxi Province showed a trend of first increasing and then decreasing. In 2019, the pollution load of TN and TP were the lowest, at 129 027.14 and 13 872.84 t, respectively;in 2019, the equal standard pollution load ratios for livestock and poultry breeding, agricultural planting, and rural life in Shaanxi Province were 20.923%, 60.130% and 18.947%, respectively;the spatial distribution of equal standard pollution load for different pollution sources TN and TP showed strong consistency. Among the 11 urban areas, the equal standard pollution load ratios for the agricultural non-point source pollution in descending order were Yulin City （16.94%）, Hanzhong City （15.42%）, Ankang City （13.06%）, Weinan City （12.93%）, Xianyang City （9.28%）, Shangluo City （8.31%）, Baoji City （8.18%）, Yan’an City （7.03%）, Xi’an City （6.89%）, Tongchuan City （1.74%）, and Yangling Demonstration Zone （0.24%）;the agricultural non-point source pollution in 11 urban areas could be divided into four types： agricultural planting pollution dominant type, agricultural planting+rural life pollution dominant type, agricultural planting+livestock and poultry breeding pollution dominant type, and mixed pollution type.

Response surface optimization of ultra high life aluminum process for removing chloride ions from high chlorine wastewater

DUAN Yue, LUO Xue-gang

2024, 63(2):  232-239.  doi:10.14088/j.cnki.issn0439-8114.2024.02.035

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Taking high chlorine wastewater generated in industrial production as the experimental object, the ultra high lime aluminum （UHLA） process was used to remove chloride ions （Cl^-） from high chlorine wastewater. Based on single factor results and Cl^- removal rate as the response value, the Box-Behnken center combination test was used to optimize the process parameters. The results showed that the calcium chloride molar ratio had a significant impact on Cl^- removal rate, temperature had a significant impact on Cl^- removal rate, while the aluminum chloride molar ratio had no significant effect on Cl^- removal rate. The degree of influence ranked from large to small as follows： calcium chloride molar ratio, temperature, and aluminum chloride molar ratio;the optimal process parameters for removing Cl^- from high chlorine wastewater using UHLA process were n （Ca）∶n （Al）∶n （Cl）=5.4∶2.9∶1.0, reaction temperature of 25.5 ℃, and theoretical Cl^- removal rate of 90.56%;the optimal process was horizontally validated using simulated wastewater, and the Cl^- removal rate in simulated wastewater was 97.85%, significantly higher than that in industrial high chlorine wastewater;ICP-MS was used to analyze the elemental changes in high chlorine wastewater before and after treatment with UHLA process. It was found that UHLA process could effectively remove anions such as SO₄^2-, SO₃^2-, and I^-, and heavy metal ions such as Sr²⁺, Cr³⁺, and Zn²⁺.

Repair effect of rapeseed, Solanum nigrum and ramie on farmland soil contaminated by cadmium and arsenic

LI Quan, CHEN Yi, LIU Li, ZHAO Qian-li, HE Bei, DU Fan

2024, 63(2):  240-246.  doi:10.14088/j.cnki.issn0439-8114.2024.02.036

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Taking rapeseed, Solanum nigrum, and ramie as test materials, the adsorption and enrichment of Cd and As in cultivated soil by rapeseed, Solanum nigrum and ramie were studied in pot experiment. Two microorganisms, Rhodopseudomonas palustris and Aspergillus niger, were applied to explore the application potential of rapeseed, Solanum nigrum and ramie to purify heavy metals polluted soil. The results showed that rapeseed and Solanum nigrum had better adsorption effects on Cd in soil, showing enrichment characteristics, while ramie plants had a poor absorption effect on Cd. The order of Cd content in rapeseed plants was： stem>root>seed, and the order of Cd content in Solanum nigrum plants was： stem>fruit>root. The adsorption effect of rapeseed, Solanum nigrum and ramie on As in soil was poor. Rhodopseudomonas palustris and Aspergillus niger had little effect on the absorption of Cd and As in the soil by rapeseed, Solanum nigrum and ramie. Rapeseed was more suitable as a remediation plant for polluted soil by Cd.

Living Space Optimization

Spatio-temporal evolution, spatio-temporal clustering and risk prevention and control of PM_2.5 exposure risk in China from 2001 to 2016

LIN Yi-chen, SUN Si-wei, PAN Yue, LIU Chao-qun, ZHOU Peng

2024, 63(2):  247-253,260.  doi:10.14088/j.cnki.issn0439-8114.2024.02.037

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The coupling population-weighted air pollution exposure risk （PPM_2.5） evaluation system was built, and the spatio-temporal evolution and spatio-temporal clustering of PM_2.5 and its population exposure risk in China was studied based on exploratory spatiotemporal analysis. The results showed that based on the time-space evolution analysis, it was found that there was a spatial mismatch between the coupling population-weighted air pollution exposure risk （PPM_2.5） pattern and the distribution of PM_2.5 concentration.The risk level of PPM_2.5 decreased with the gradient from the center to the periphery, but the overall pattern of high in the east and low in the west remained unchanged during the study period. The spatial and temporal evolution of its equilibrium showed an enhancement of the overall imbalance and the local equilibrium was more likely. Based on the K-means clustering analysis of spatio-temporal scanning statistics, four types of exposure risk were defined： stable low risk, continuous growth risk, continuous high risk and low-high risk gradual change. The distribution of each type was significantly different with different demographic and economic characteristics. The development of differentiated air pollution warning and prevention strategies based on the spatial and temporal clustering zones of different PM_2.5 population exposure risk could help improve urban resilience and provide a theoretical and practical basis for the implementation of the development strategy of “Healthy China”.

Temporal and spatial evolution analysis of habitat quality in ecologically vulnerable areas based on PLUS-InVEST model

LI Zi-han, YU Hui, GONG Fei, WANG Tian-zhu, LI Peng-shan, PAN Yi-xi, LIU Si-yuan

2024, 63(2):  254-260.  doi:10.14088/j.cnki.issn0439-8114.2024.02.038

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Based on the PLUS model, the land use situation in ecologically vulnerable areas of Aba Prefecture in 2030 was predicted, and the InVEST model was used to calculate the habitat quality in 2000, 2010, 2020 and 2030, and analyze its temporal and spatial evolution. The results showed that the degradation of grassland and wetland in the study area was significant and the bare land continued to increase. It was estimated that the area of bare land would reach 334.38 km² in 2030; compared with 2000, there would be 204.55 km² of wetland degradation. Among the driving factors, rainfall was the main factor limiting the expansion of forest land and wetlands, which reflected the importance of water conservation function; there was little difference in the degree of grasslands affected by various factors, the grass land generally grew in places far from the government, and the area expansion was limited by DEM; air temperature was the main factor leading to the increase of bare land. The habitat quality was generally high, but the spatial distribution varied greatly, and there was a slow deterioration trend. It was expected that the area with low habitat quality would increase by 670.28 km² in 2030 compared with 2000, mainly caused by the expansion of cultivated land and construction land. The rate of habitat quality degradation would slow down in the future, but artificial measures were still needed to prevent the decline.

The estimation and release of the construction land consolidation potential of rural residential areas based on potential type differentiation：Taking a county in hilly region of South China as an example

TAO Feng, XU Xian-sui, CHEN Rong-qing

2024, 63(2):  261-267,封三.  doi:10.14088/j.cnki.issn0439-8114.2024.02.039

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The potential of rural residential construction land consolidation from the perspectives of other idle land, idle construction land and standard-exceeding residential land was calculated, the regional consolidation benefits from the economic perspective were explored, and the time sequence of construction land consolidation based on the consolidation potential and benefits was determined. The results showed that the potential of rural residential construction land consolidation in the study area was sufficient, and the potential of standard-exceeding residential land consolidation was significant; the consolidation efficiency of other idle land and idle construction land was superior, and the difference between the income and expenditure of the standard-exceeding residential land consolidation was obvious; the release of rural residential construction land consolidation potential was related to the consolidation area, benefits and time sequence, which was determined by regional capacity and demand.

Spatial-temporal evolution analysis of population in dam area of more than 5 000 mu of arable land in Guizhou Province

TANG Tian-jun, ZHOU Zhong-fa, ZHANG-FU Xian-mei, HUANG Deng-hong, DENG Fang-fang

2024, 63(2):  268-274.  doi:10.14088/j.cnki.issn0439-8114.2024.02.040

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The GIS spatial statistical tool was used to analyze the population data of 21 WorldPops in the arable land dam area of more than 5 000 mu in Guizhou Province from 2000 to 2020, and the spatial and temporal pattern and change characteristics of population distribution in the arable land dam area of more than 5 000 mu in Guizhou Province in the past 21 years were quantitatively revealed. The results showed that the population of arable land dam area in Guizhou Province showed a trend of increasing first and then decreasing. According to the characteristics of the population growth curve, it could be divided into four stages： stable growth period（2000—2006）, rapid fluctuation growth period（2006—2010）, rapid negative growth period（2010—2015） and slow decline period（2015—2020）, with an overall decrease of 9 900 people, of which 5 000 mu of arable land dam area increased by 9 400 people and 10 000 mu of arable land dam area decreased by 19 300 people; the population distribution of arable land dam area of more than 5 000 mu was mainly relatively lower-density agglomeration area and lower-density agglomeration area, and the population distribution difference was obvious; the spatial correlation of population density was generally manifested as no significant difference, and locally manifested as HH, LL and HL agglomerations; the migration range of the population center of gravity in the dam area was small, and the meridional and zonal changes showed a reciprocating trend.