Digital industrialization and industrial digitization are the “double dimensions” of digital economy, and their coupling degree is of great significance to optimize the development structure of digital economy. This paper revealed and expounded the mechanism of coupling between digital industrialization and industrial digitization. A theoretical model was established to evaluate the coupling coordination degree, and an index system was designed to evaluate the coupling coordination status and trend. Based on the panel data of 11 provinces and cities of the Yangtze river economic belt from 2013 to 2018, this paper empirically analyzed the coupling coordination degree of digital industrialization and industrial digitization in the Yangtze river economic belt. The results show that the development level of digital industrialization and industrial digitization in the Yangtze river economic belt has been steadily improved, but the overall coupling coordination degree of the Yangtze river economic belt is not high and the regional gap is obvious. The digital industrialization has a tendency of lagging behind the industrial digitization. From the aspects of accelerating the development of new digital industries, and using “new infrastructure” to facilitate the digital transformation of traditional industries, and building a better system for the coordinated development of digital economy among regions and the digital transformation within regions, strengthening the cultivation and incentive of digital talents, this paper puts forward some policy suggestions to promote the integrated development of digital industrialization and industrial digitization in China.

With the rapid improvement of urbanization, large cities have gradually formed a polycentric spatial structure through epitaxial expansion and connotative development. Under the effect of polycentric spatial structure, urban space, especially the change of housing price space, shows heterogeneity and complexity. Taking the fast-developing Hefei City as an example, this paper uses the geostatistical method to study the spatial differentiation characteristics of urban housing prices from different spatial scales, and analyzes the dominant factors of housing price differentiation by constructing the hedonic price model, to reveal the logical relationship between urban spatial structure and housing price space. The results show that: (1) On the scale of the main city, the spatial distribution of housing price is consistent with the polycentric structure, and three high housing price zones are formed in each center; (2) On the scale of central areas, the housing prices in each central area present a mixed distribution of circle layers and and fan-shaped. The difference in the impact scope of centers of different scales on their surrounding housing prices has formed different spatial variation patterns; (3) Among the three types of characteristics that influence the spatial differentiation of house prices, the structural and neighborhood characteristics have great influence on the main city, and scarce landscapes, educational resources and greening rate are the most important factors for spatial differentiation of housing prices in the main city; (4) The main factors of the spatial differentiation of house price in different central areas are various. The location characteristics have the greatest impact on the old city center, and the structural characteristics and location characteristics have a large impact in administrative center. Besides, the structural characteristics are the most important factors affecting housing prices in the center of the new district.

Evaluating the coupling and coordinated development of land eco-economic system is helpful to reveal the evolution law of man-earth areal system, and to promote the sustainable utilization of land resources. Taking Jiangjin, an ecologically sensitive area in the Three Gorges Reservoir area, as an example, this paper studied the coupling mechanism of land eco economic system and constructed an evaluation index system of the coupling and coordinated development of land eco-economic system. Then, we analyzed the coupling coordination development characteristics of the land eco-economic system in village scale based on the model of land comprehensive evaluation and coupling coordination degree model. The results show that the development of land ecosystem in Jiangjin district is in a bad trend, which shows the characteristics of low-level village space squeezing high-level village space, and the development of land ecosystem shows obvious spatial differentiation. The development of land economic system in Jiangjin district is in a good trend. But the development of land economic system has great spatial difference, both in village scale and urban-rural scale. The land economic system in the urban area is better than that outside the urban area, and the villages with good land economic system are basically concentrated in the urban area. The coupling and coordination development of land eco-economic system in Jiangjin District evolves in a favorable direction, which means that land eco system and land economic system are promoting each other. However, the overall level of coupling and coordination of land eco-economic system in the whole district still needs to be improved, because the coupling and coordinated development of land eco-economic systems in most regions are in the middle and low level and some villages are still in a state of maladjustment. The coupling and coordination development of land eco-economic system in Jiangjin district has significant spatial differences. The high-level villages are sporadically distributed, while the villages in medium and low level are widely distributed. The villages in maladjusted state are mainly distributed outside the urban area.

Lakes provide important freshwater resource for regional development. Climate change and human activities significantly affect the spatial and temporal distribution of water resource at the global scale. Consequently, frequent floods and droughts occur in lake catchments, impacting local water security and aquatic ecosystem health. Lake catchment is a relatively independent geographic unit, and thus, has been used as an ideal area for hydrology research. Focusing on several new hydrological issues in the 21st century, this article reviewed up-to-date hydrology research status in topics including extreme hydrological events, hydrological impacts of land cover changes, integrated modelling of lake catchment, evolution and future projection of water resource availability of lake catchment. Exemplified in Poyang Lake catchment, a large freshwater lake in the middle Yangtze River, research gaps are identified and future directions are suggested. This article may enrich the research context of catchment hydrology and limnology, and may be of reference value to the future development of relevant science disciplines.

The water resource is a critical factor that restricts the social and economic development. Comprehensively and objectively evaluation of water resources carrying capacity is of great theoretical and practical significance to promote the coordination between water resources utilization and population, economy, society and development. Taking 31 provinces (autonomous regions and municipalities) as the research unit, based on the ecological footprint model, it estimates the supply and demand condition about the ecological balance of water resources in China from 2003 to 2018, and it predicts the variation trend for the future by ARIMA model. The results show that: (1)The interannual fluctuation of China’s per capita water resources carrying capacity is large, while the ecological footprint of per capita water resources shows a small fluctuation trend that firstly increases and then decreases. The overall ecological budget of per capita water resources is surplus, but it approaches the edge of the deficit with the years that have low precipitation. (2)Geographically, China’s water resources carrying capacity has maintained a macro-pattern, which has a surplus in the south and a deficit in the north. The per capita water resources are mainly in surplus and overload areas, and the ecological budget of water resources has significant difference among regions. (3)China’s agricultural water takes up the highest proportion of the four categories of accounts. During the study, the per capita agricultural and industrial water footprint change from increase to decrease, and the per capita living and ecological water footprint increase progressively year by year. Except for Beijing, the main water accounts of other provinces are agriculture and industry. (4)The ecological budget of per capita water resources in China presents a regional pattern of “whole stable and local variation”. In the past 15 years, the ecological overload of water resources in 20 provinces (autonomous regions and municipalities) has accelerated. (5)In the future, the ecological budget of per capita water resources will deteriorate in some areas from 30°N-40°N, but gradually improve in most areas. The southeast and northwest regions have great potential to improve the ecological environment of water resources, and the Qinghai-Tibet Plateau will deteriorate. The severe warning areas may be formed in Shanxi, Shaanxi, Henan, Shandong, Jiangsu and Liaoning.

The barrier of the Three Gorges Dam resulted in fragmentation of fish habitats. In order to understand the connection between the three Gorges lock and the fish in the upper and lower reaches, study the fish passing ability of the three Gorges Lock, the changes of fish composition, diversity and community structure were analyzed in June 2009, February 2012, February 2017 and February 2018. During this survey, 39 species of fishes were captured，belonging to 6 orders，10 families and 32 genera. Among these fishes, 4 species were endemic to the upper reaches of the Yangtze River and 2 species were endemic to the Yangtze River (paddlefish and hybrid sturgeon). Four species of fish appear more frequently which were Hemiculter leucisculus, Hemiculter bleekeri, Parabramis pekinensis and Pelteobagrus vachelli. There were 23 species of fish may have the ability to pass through the lock, 9 species of which can pass through the lock smoothly or settle in the lock. Protosalanx hyalocranius and Neosalanx taihuensis with weak swimming ability were also distributed in the lock, which was speculated that early larva fish could also reach the downstream through the lock to achieve the purpose of resource exchange up and down. This study provided practical basis for the ecological function of ship lock and the construction of new passageway.

Based on the investigation of fishery catches in two regional river sections (Panzhihua and Qiaojia ) in the middle and lower reaches of Jinsha River from 2012 to 2017, the biological and ecological characteristics of endemic fish in the upper reaches of the Yangtze River were studied. On this basis, the protective measures for endemic fish in the middle and lower reaches of Jinsha River were discussed. The results showed that: a total of 25 species of endemic fishes, belonging to 17 genera and 4 families, were collected during the period of 2012-2017. After the water fillings of Xiangjiaba and Xiluodu Reservoirs, the abundances of the main endemic fishes decreased significantly. Except Anabarilius liui, other 24 species of fishes prefer to the habitats with flowing water and gravels. The food characteristics of endemic fish, water temperature during spawning period and distribution characteristics of juvenile shelter can affect their biological characteristics to a certain extent. Based on the analysis of biological and ecological characteristics, it is considered that cascade development and sustained overfishing in the main and tributaries of the middle and lower reaches of the Jinsha River are the main factors affecting the variations in endemic fish resources in this region. Therefore, it is suggested that the naturalization of important tributary habitats should be maintained at the level of river basin planning, while extending the lengths of the river sections with the flowing habitat in the backwater fluctuation areas of each reservoir in the mainstem of the middle and lower reaches of Jinsha River as far as possible; in addition, fisheries management should be strengthened in important habitat areas, and artificial propagation of endemic fish should be accelerated in the future.

The Fu River watershed is one of the major sources of runoff and sediment into the Three Gorges Reservoir. Based on observations of daily runoff and sediment transport rate from 1980-2018 at the hydrological station of Fu River watershed, this study carried out analyses on runoff-sediment time series and rating curves on multiple temporal scales, and quantitatively differentiated contribution rates of meteorological conditions and human activities. Results showed that: (1) On an annual scale, the means of annual runoff and sediment discharge exhibited significant downward trends and typical three-stage characteristics, taking 1997 and 2012 as the turning years; On a monthly scale, high values of runoff and sediment discharge mainly occurred in July, August and September; On a daily scale, the Concentration Indices of runoff and sediment are 0.5 and 0.91 respectively, indicating that extreme events runoff and sediment became more urgent. (2) Long-term rating curve analyses showed that the external driving factor a presented a significant upward trend, while the sediment transport factor b exhibited a significant downward trend; Event-based analyses on Concentration-Discharge loops showed that, clockwise and counterclockwise loops were two prominent types of C-Q loops. Frequencies of occurrence of the above two types presented downward and upward trends, respectively, demonstrating increased effect of human activities and decreased effect of river sediment transport capacity. (3)Human activities were proved to be the primary driving factor, and corresponding contribution rates to runoff and sediment discharge accounted for more than 86% and 97%, respectively. The above conclusions could provide basic data and scientific evidences for management of runoff and sediment resources in the Yangtze River Basin.

Land cover has an important relationship with global ecological environment change. As the main way to get the large-scale land cover information, remote sensing classification technology plays an essential role in monitoring land cover change. However, due to the requirements of monitoring research on image time series and the characteristics of mixed spectrum presented by pixels, the accuracy of existing urban land cover classification methods still needs to be improved. In order to accurately assess the ecological effects of urban land cover changes, it is very important to find a simple and feasible remote sensing classification method with high classification accuracy. Based on Landsat 8 satellite remote sensing images, this research established a relatively representative urban land cover classification system. Then we set up a new urban land cover classification method by integrating the phenological characteristics of ground objects to the traditional supervised classification method. After that the improved classification method was applied to the land cover classification in Jintan district, and finally we statistically analyzed the change of area of each land cover type in Jintan district form 2016 to 2018. The results showed that compared with the traditional supervised classification method, the supervised classification method with phenological characteristics can effectively improve the classification accuracy of each land cover type. Moreover, with the implementation of the biodiversity protection policy of Jiangsu province, the area of each land cover type in Jintan district changed a lot from 2016 to 2018. On the whole, this research integrated the advantage of phenological characteristics to the process of land cover classification, which not only ensures the simplicity and feasibility of the classification method, but also effectively improves the classification accuracy, providing a reference for ecological analysis of land cover change.

Based on the "top-down" energy inventory method, the anthropogenic heat emissions and their temporal and spatial distribution characteristics of Changsha Zhuzhou Xiangtan Urban Agglomeration in 2017 were studied. At the same time, the weather research and forecasting (WRF) model and its coupled UCM are used to carry out numerical simulation experiments in summer and winter respectively, and the seasonal differences of artificial heat emission warming effects in different types of built-up areas are quantitatively analyzed. The results show that: (1) in 2017, the total anthropogenic heat emission of Changsha Zhuzhou Xiangtan was 3.49×1017J/a, and the average anthropogenic heat emission intensity was 14.22 w/m2. The contribution rates of industry, construction, transportation and metabolism of human new towns to anthropogenic heat were 48.15%, 40%, 11.3% and 0.55%, respectively.(2) With the introduction of artificial heat, the average temperature of the main urban areas in summer and winter increased by about 0.7℃ and 1.5℃ respectively, and the effect of increasing temperature in winter was twice that in summer.(3) The effect of artificial heat emission in different density zones is different.In general, industrial / commercial area > high density residential area > low density residential area.

Vegetation coverage is one of the main indicators of ecosystem change. Improving the spatiotemporal scales of vegetation observations and the methods of dynamic changes of vegetation and their driving factors can provide more information about vegetation changes, and better understand the characteristics and changes of the ecological environment in the region. The purpose of this study is to evaluate spatial-temporal changes of vegetation coverage and its driving factors in Jinsha River Basin (JRB) from 2000 to 2015, China. The evaluation will be performed using the enhanced vegetation index (EVI) of moderate resolution imaging spectroradiometer (MODIS), Sen and Mann-Kendall model, partial correlation analysis and grey correlation analysis (GRA) method. The Spatiotemporal variation of vegetation coverage were examined by using Sen and Mann-Kendall model, partial correlation analysis and GRA method were applicated to evaluate the driving factors of vegetation coverage change and its time lag to climate at pixel, ecological zone scale in JRB for growing season. The characterization and spatial distribution of the response period of vegetation coverage to climatic factors were performed through the GRA method. The results indicated that, vegetation coverage of the study area generally increased in the past 16 years, with a tendency being 0.011/decade. The areas with vegetation coverage showed improvement and degradation accounted for 55.53% and 28.95% of the total study area, respectively. The air temperature driving zoon (32.627%) was more than the precipitation driving zoon (28.265%). Vegetation coverage change was mainly affected by precipitation in semi-arid areas, while it was mainly affected by temperature in semi-humid and humid areas, but the correlation between climatic factors and vegetation was affected by topography and vegetation types. The time lag analysis indicated that the response of vegetation coverage to climate was not significant in semi-arid areas and the response of vegetation coverage to temperature was slower than cumulative precipitation in most semi-humid and humid areas, and response time of vegetation to climatic factors varied with altitude and vegetation types.

Drought is one of the most commonly occurred natural disasters. With the intensification of human activities and climate change, the production and life of human being have been highly influenced by the frequently occurred drought events. Based on the grid precipitation data with resolution of 0.25°×0.25° in the Hanjiang River Basin from 1961 to 2018, the process, frequency and intensity of meteorological droughts were analyzed at monthly, seasonal, and annual scales by using the standardized precipitation index (SPI). The characteristics of the spatial and temporal evolution of meteorological droughts in the Hanjiang River Basin were then comprehensively investigated. Results indicate that: (1) The SPI value can better reflect the characteristics of meteorological drought variation in the Hanjiang River Basin. With increase in time scale, the magnitude of SPI fluctuation tends to decreases and the stability accordingly increases. The abrupt change points of the meteorological droughts at monthly, seasonal, and annual scale occurred at 1980 and 1988, and 1994, respectively. The significant periodicity of 2 and 4 years were detectable in seasonal and annual meteorological droughts. (2) Since the 1990s, the central region of the Hanjiang River Basin presented an aridification trend while the eastern and the western regions exhibited a humidification trend. For the whole catchment, the frequency of droughts tends to increase in general, with the higher drought intensity occurring in the central region and the lower occurring in the east and west regions. The lower reaches of the Tangbaihe River and the area nearby the Danjiangkou Reservoir showed a significant aridification trend. Meanwhile, the area above the Danjiangkou Reservoir could be characterized with the highest drought frequency and intensity, as well as the more frequently occurring for the light and moderate drought events. (3) The seasonal meteorological droughts are different for different regions. For instance, the area below Danjiangkou reservoir has the most significant trend of autumn drought, the summer droughts are usually in the levels of light drought or moderate drought with a relatively higher frequency, and mainly manifesting in the Tangbaihe area. The autumn drought tends to increase with a higher intensity, mainly occurs in the area above the Danjiangkou reservoir.

In this paper, VGG16_BN Deep Learning network algorithm is used to classify the different ground objects over the coastal wetland in Yancheng of Jiangsu province, based on the high spatial resolution remote sensing images captured by GF-2 satellite. The results of this classification algorithm are compared with those of three other algorithms, including VGG16, Support Vector Machine (SVM) and Back Propagation (BP) neural network models. The overall classification accuracy and Kappa coefficient obtained from the VGG16_BN Deep Learning network algorithm are respectively 99.32% and 0.99, which are significantly higher than other algorithms. In addition, based on local visualization analysis, VGG16_BN network algorithm can effectively maintain the regional consistency of homogeneous features over a large area and avoid the salt-and-pepper noise. The continuity and boundary of line feature extraction such as road and river are relatively complete and clear.

Chlorophyll-a is an important indicator to estimate water quality, and there are no easy solutions to accurately assess the chlorophyll-a of clean water. In this study, the GF-1 images and neural network method were applied, and a simulating model of chlorophyll-a in Qiandao lake was established. The distribution and variations of chlorophyll-a was detected and the superiority of the method was analyzed. The results show that it's feasible to simulate the concentration of chlorophyll-a in clean water using the proposed neural network method since the high value of coefficient; The spatial analysis revealed that the overall concentration of chlorophyll-a in Qiandao lake is quite low and the high values distributed mainly in the southwest and northeast regions. Moreover, we also found that the concentration of chlorophyll-a was quite stable with average value of 1.70 to 1.75 μg/L during the study period.

The middle reaches of the Jialing River have the most intensive hydropower projects, which significantly impact the development of phytoplankton communities in the lower reaches. Based on this, this study conducted a seasonal survey on the reaches in 2019 to investigate the current status of the phytoplankton community structure and analyze the impact of environmental changes on the composition and quantity of phytoplankton species. Specifically, the following research findings have been made. First, there is a certain degree of pollution in the investigated reaches, especially reflected in the exceeding of the total phosphorus (TP) content. Second, a total of 196 species, which belonged to 91 genera in 7 phyla, were identified, and their annual mean of total density was 4.23×106cells/L. Moreover, the dominant phyla were ordered as Chlorophyta > Bacillariophyta > Cyanophyta. Compared with the historical data, the richness and relative density of Bacillariophyta decreased, while those of Chlorophyta and Cyanophyta increased, suggesting the eutrophication trend of the investigated reaches. Furthermore, the results of the biodiversity index also show a certain degree of pollution in the reaches. Third, the results of Classification and Regression Tree showed that phytoplankton might proliferate in reaches with abundance TP, high pH, and moderate secchi depth. Fourth, according to the Redundancy Analysis, all dominant species of Chlorophyta identified were positively correlated with the water temperature and TP, while only Cyclotella with the highest dominance in the Bacillariophyta species preferred the higher TP and lower flow velocity (FV). Furthermore, the Cyanobacteria dominated by filament strains that adapt to a certain FV preferred high water temperature and were positively correlated with the FV. It is concluded that the current eutrophication and low-speed flow of the Jialing River are the main reasons of the Bacillariophyta that prefer clean water and high FV gradually losing their dominance, and the increasing dominance of Chlorophyta, Cyanophyta and Cyclotella that prefer high nutrition and low FV. For different power station reservoirs, there is a risk of Cyanophyta and Chlorophyta blooms in summer with high temperatures, and a Bacillariophyta bloom dominated by Cyclotella in early spring with low temperatures. It is recommended that the water environment of the reaches should be comprehensively managed to reduce the eutrophication, and the sluices need to be opened in time to increase the FV of the reservoir, thus reducing the potential risk of algal blooms.

The hydrochemical properties of five points were monthly monitored in Jiangjia Spring from from December 2017 to November 2018, in order to reveal the effect on hydrochemistry of karst spring water and karst carbon cycle from photosynthesis of aquatic plants and gas exchange. The results showed that the Ca ²⁺ concentration and HCO ₃^- concentration at JJQ3 were significantly low in the months with less precipitation, comparing with those at JJQ1 and JJQ2. Meanwhile the dissolved oxygen (DO) negatively correlated with conductivity (EC), Ca ²⁺ and HCO₃^- concentrations. It indicated that HCO₃^- generated from carbonate dissolution was partly converted into stable organic carbon through photosynthesis of aquatic plants, which enhanced the karst carbon sink. However, the high flow rate could limit the photosynthesis of aquatic plants, resulting in little difference of chemical properties among monitoring points in the month with more precipitation. Despite that HCO₃^- concentrations at JJQ4 were similar to those at JJQ1 and JJQ2, while the pH and DO at JJQ4 were significantly higher than that at JJQ1 and JJQ2, and the stable isotopes of dissolved inorganic (δ13CDIC) at JJQ4 were heavier than those at JJQ1 and JJQ2. The above phenomenon may attribute to the gas exchange between water and atmosphere because of head fall, which caused that the oxygen in the atmosphere dissolved into the water and the CO₂ in the spring water was released into the atmosphere due to high pCO₂. The hydrochemistry of Jiangjiaquan were controlled by photosynthesis of aquatic plants as well as gas exchange between water and atmosphere. Although the two factors had similar effects on hydrochemistry, they brought different effects on karst carbon cycle. Especially, CO₂ degassing would further weaken the effect of karst carbon sink, at the presence of strong acid such as H₂SO₄. Therefore, it was necessary to distinguish the two factors, in order to accurately estimate the karst carbon flux.

In order to explore the air flow variation characteristics of karst cave, to reveal the temporal and spatial variation and the change mode of the ventilation effect in karst cave. With two monitoring cycle during January 2016 to June 2019 , this study had a 32-month data collection about the temperature, relative humidity, CO2 concentration and pressure in Mahuang Cave which located in Suiyang. Base on the mode to analysis, the result shows that there are three ventilation modes in the Mahuang Cave, the limited ventilation mode in the summer, the active ventilation mode in the winter and the transition phase in the spring and autumn. The circulate of air flow is restricted in the summer, active in the winter and some exchange in the spring and autumn. The structure of the cave affects the ventilation mode and the ventilation effect also affects the microclimate. According to the influence of the ventilation effect, the Mahuang Cave can be divided into three parts: 1#-5# monitoring point with air exchange, 6#-9# monitoring point with turbulence and 10#-15# monitoring point with relative stable air environment. Due to the special structure of the cave, there is "gorge wind " caused by " Canyon effect " in the middle of the cave, and there is obvious airflow in the middle of the cave in spring and autumn. Analysis of karst cave ventilation mode and study the mode and variation character of ventilation effect in karst cave, it is of great significance to the study of sediment growth, climate change and carbon cycle model.

The foundation for the implementing the current policy of garbage sorting smoothly lies in the response and participation of urban residents. Based on the Normative Activation Theory, this paper studied the influence of personal norms and social norms on urban residents’ participation in garbage sorting by constructing multiple ordered Logistic model and hierarchical regression model based on the micro data of 1 156 questionnaires from 4 megacities. Results showed that the personal norm was the key variables affecting the participation of urban garbage sorting which affected by the awareness of consequence and ascription of responsibility. Meanwhile, the descriptive norm such as the atmosphere of the community and situations and the mandatory norms had positive role in the relationship between the personal norms and the urban residents’ garbage sorting by stimulating the herd behavior and psychological pressure respectively. Therefore, the countermeasure that increasing the report both about the serious consequences of garbage litter and propaganda of benign social benefits of classification, advocating that garbage classification incorporated into the residents' convention and the mode of fixed point and special person supervision to strengthen the pressure of social rules, normalizing the popularization of specific knowledge of garbage classification and creating the atmosphere of participation has been put forward to promote the residents’ participation.

As Chinese core region of grain production, the major grain area plays an important role in guaranteeing food security in China. Therefore it is full of meaning to research spatiotemporal differentiation and evolution characteristics of grain climatic production potential in Chinese major grain area, especially under the background of climate change. Using step correcting mechanism model based on daily monitoring data of 341 meteorological stations in 13 provinces of Chinese major grain area, this study investigates grain climatic production potential and its spatiotemporal evolution from 1981 to 2015. The results indicate that: （1) The annual average grain climatic production potential in Chinese major grain area is 9 171.17 kg/hm², and temporal evolution path of grain climatic production potential in Chinese major grain area is generally stationary, however photosynthetic production potential has been decreasing and light-temperature production potential has been raising. The variation of light, temperature and water climatic resources has a little comprehensive effect to Chinese grain production. （2) Photosynthetic production potential determined by illumination in the northwest is higher than in the southeast, however spatial structure of grain climatic production potential reorganizes after continuous superposition of light, temperature and water climatic resources. Grain climatic production potential in Chinese major grain area exhibits a significantly spatial pattern, characterized by higher in the southeast than the northwest. Further, the higher potential areas are mainly concentrated in the Plain of Yangtze River Middle and Lower Reaches and Chengdu Plain, where climate and terrain condition is suitable for cultivation. （3)The evolution of grain climatic production potential in Chinese major grain area has three characteristics. The first characteristic is that scope of the higher potential areas has been narrowing; the second is that scope of the lower potential areas basically holds; and the third is that spatial disparity in the medial potential areas has been weakening.

A field experiment was set up to explore the effects of different application rates of soil conditioners on soil nutrients, texture, microaggregates, enzyme activity and microbial abundance in cadmium contaminated paddy fields. Six treatments were tested in the experiment, including T0, T1, T2, T3, T4 and T5, corresponding to the addition of soil conditioners 0, 1 500, 3 000, 4 500, 6 000 and 7 500 kg·hm^-2. The results showed that the soil conditioner, soil pH (0.66% ~ 6.75%), bulk density (0.97% ~ 9.71%), cation exchange capacity (22.68% ~ 64.45%), alkaline nitrogen (7.94% ~ 29.26%) and available potassium (0.28% ~ 21.99%) were increased under different treatments. However, it has little effect on texture, available phosphorus and micro-aggregate composition. Which affects soil microbial environment, inhibited urease and catalase activity, the adundance of bacteria and actinomycetes. Soil conditioners reduced soil available cadmium (12.34% ~ 24.78%) and brown rice cadmium content (7.69% ~ 64.10%) by affecting soil physicochemical properties and microbial environment. The correlation analysis showed that the application rate was significantly positively correlated with soil pH, cation exchange capacity, alkaline nitrogen and available potassium, it was significantly negatively correlated with available phosphorus, urease and catalase, and had no significant correlation with soil available cadmium and brown rice cadmium. In summary, considering the effects of cadmium remediation, soil environmental impact and economic costs, T2 (3 000 kg·hm^-2) was the optimum treatment.

The article calculated the emissions of agricultural non-point source pollutants, key pollution sources, key polluted areas, emission intensity and spatial distribution, based on the analysis of three kinds of pollutants: COD, total nitrogen (TN) and total phosphorus (TP) in the agricultural non-point source pollution in 155 counties in the Huaihe Ecological Economic Belt, in order to clarify the current status of agricultural non-point source pollution and implement comprehensive management of agricultural non-point source pollution. The results showed that there were 199.33×104 t, 107.20×104 t, and 12.64×104 t for the emissions of COD, TN, and TP from agricultural non-point source pollutants in the Huaihe Ecological Economic Belt in 2018, respectively, and there were 69.23 kg/km², 34.71 kg/km², 3.42 kg/km² for the emission intensities; The key pollution sources were farmland fertilizations and livestock and poultry farming, the key pollutants were TN and TP, and there were Jianhu County, Xinghua County, and Luohe City, including 10 counties (cities and districts) for the key prevention and control areas. The type of Farmland fertilizer pollution was the most widely agricultural non-point source pollution in the Huaihe Ecological Economic Belt. It was the most difficult to control for the comprehensive pollution type in agricultural non-point source pollution. Therefore, it is high spatial heterogeneity of agricultural non-point source pollution in counties in the Huaihe Ecological Economic Belt, and it should be implemented for the targeted control policies according to different pollution types in different regions.

Based on the panel data of 74 counties in Hubei Province from 2005 to 2017, construct a spatial weight matrix based on traffic weight, use the spatial Dubin model to empirically study the spatial spillover effect of the transformation of cultivated land use on farmers’ income, and further reveal the specific laws and characteristics of the spillover effect. Research results: (1) All forms of cultivated land use transformation and farmers' income levels have significant positive spatial autocorrelation. (2) The spatial autoregressive coefficient of farmers' income level is 0.65, indicating that there is a positive spatial spillover effect in the increase of farmers' income in neighboring counties, that is, farmers' income in this county will increase by 1%, and farmers' income in neighboring counties will increase by 0.65%. (3) Spatial spillover effects between neighboring counties are mainly driven by changes in the amount of cultivated land, agricultural labor and infrastructure input patterns. Among them,
the spatial spillover effects caused by changes in agricultural labor input patterns account for 69% of the total positive effects. The amount of cultivated land accounted for 15%, and the form of infrastructure investment accoullted for 12%. Research conclusion: Attention should be paid to improving the synergy of the farmland utilization system between counties, and using its spillover effect to promote the common development of all counties in Hubei Province and the synergistic increase of farmers' income.

Under the background of the continuous improvement of the specialized agricultural service system, using the survey data of 704 rice farmers in Hubei and Jiangxi provinces, the binary Logit model is used to empirically analyze the impact of rice farmers' risk perception and specialized agricultural services on their adoption behavior of biological pesticide technology. The results show that: (1) the adoption rate of biological pesticide technology by farmers is low, and 55.54% of rice farmers still do not use biological pesticide. (2) Risk perception has a significant impact on rice farmers' adoption of biological pesticide technology. Specifically, rice farmers with higher technology and market risk perceptions are less likely to adopt technology. (3)Specialized agricultural services have a significant positive effect on rice farmers 'adoption of biological pesticide technology, and can alleviate the inhibition effect of risk perception on the rice farmers' adoption of biological pesticide technology. (4) Compared with large-scale households, agricultural socialization services are more effective in alleviating the inhibitory effect of market risk perception on the adoption of biological pesticide technology by small farmers, but the mitigation effect of their technical risk perception is not obvious. Therefore, while increasing technical publicity and field guidance, improving the agricultural materials market and agricultural product market system, and increasing the intensity of biological pesticide subsidies to reduce farmers' technology and market risk perceptions, it is necessary to promote the promotion and application of biological pesticide technology by expanding the service content and service objects of specialized agricultural services and optimizing the agricultural market environment of small farmers.