The economic gradient evolution is the characteristic of regional spatial polarization, and it is also a hot topic in the study of Economic Polarized Area. This paper firstly constructed the theory of economic gradient evolution according to Perroux’s “growth pole theory” and Hirshman’s “polarizing and trickling-down effect theory”, then taken the Yangtze River Delta as the empirical study area, calculated 42 cities’ economic gradient value by means of  principal component analysis (PCA) method, studied their gradient distribution and evolution characteristics from 2000 to 2015 by using the methods of regional difference coefficient, spatial autocorrelation analysis, cluster analysis, geographical regionalization and gradient-distance curve simulation The results show that the regional internal differences firstly increased and then decreased, the spatial pattern firstly gathered and then dispersed, the slope of gradient curve firstly become steeper and then slower. This polarization reversal law is not only verified the “growth pole theory” and “the polarizing and trickling-down effect theory” again, but also can be used as an important evidence to judge whether an economic polarized area has been formed.
Key words：polarized area；economic gradient; polarization reversal law; Yangtze River Delta

Based on the gravity and passenger shift among cities and towns in Zhejiang province, this paper builds the urban linkage network, then uses the methods of social network analysis and comparative analysis to research the network characteristics from the perspective of the grades of point, line and network. The result is that: Hangzhou municipal district has the largest external linkage, and the following two are Ningbo municipal district and Wenzhou municipal district. The scale classification of external linkage is particularly obvious, but the scale distribution of passenger linkage is more homogeneous. The spatial distribution of node scale based on two methods shows that the north is high and the south is low, while the middle is a prominent area. The spatial distribution based on first and second linkage shows that the geographic segmentation complies with the form of center-radiation. However, there are differences between the two methods, the strong linkages mostly distribute among the regional center and towns circling them. Simultaneously, the density of urban network in Zhejiang province is still low, but the control force of Hangzhou municipal district and Ningbo municipal district is stable, which presents an inadequate coordinating network. Aiming at current situation, this paper suggests that the governments should optimize urban scale system and broaden ways of communication and cooperation between cities and towns.
Key words：urban network; spatial linkage; characteristic; Zhejiang Province

Influencing factors of farmers’ willingness on homestead replacement (FWHR) were usually detected based on single level in previous studies, in which multi-level effects of the factors were ignored. To solve this issue, questionnaire survey was conducted on 394 households from 17 villages in Suzhou and Changzhou, which are located in the developed area, and multi-level factors’ effects on FWHR were analyzed by using multi-level regression model. Results show that the farmers’ willingness in Suzhou is lower than that in Changzhou, and significant difference of FWHR exists in different villages, 75.12% of which can be attributed to the differences among villages. The factors of age, education level, and the main source of household’s income have significant positive effects on FWHR, while the family size has negative effect on FWHR. The village’s average income of households and the environmental level significantly weaken the positive relationship between farmers’ main income source and FWHR, while the level of village’s economic development and distance to the nearest city or town strengthen the aforementioned positive relationship. In addition, the factors from the village-level explain 95.69% of the correlation between farmers’ main income source and FWHR. It is indicated that factors from village-level lead to the difference of the FWHR among villages through changing the influence degree of the factors from farmer-level. Therefore, to promote the work of farmers’ homestead replacement, the influencing factors from farmer-level and village-level should be considered comprehensively, the relevant supporting policies and social security system should be improved. Meanwhile, the publicity of rural homestead replacement polices should be strengthened, the rural homestead planning should be optimized. In addition, the public service facilities and the environment in rural area should be improved, as well as the farmers’ income should be increased.
Key words：rural homestead; replacement willingness; multi-level logistic regression model; village level; farmer level

Taking Poyang Lake region as an example, we applied the Logistic regression to calculate the driving effects between various factors and land-use types. A Cellular Automata model combining the Markov method was built to simulate the land-use change in the Poyang Lake region. We completed the precision tests of the proposed model and predicted the developing trends of the land-use change in the region. The results show that: 1) The variation of land use types in Poyang Lake region had an obvious ascending trend from 2000 to 2010.  Grassland was the most active land-use type. The area of cultivated land had sharply declined, and the expansion of the residential land kept stable. 2) The driving directions and the explanatory abilities of different factors had significant differences on influencing land-use change. The overall explanatory effect was good and all the ROC values were higher than 0.81. 3) The overall Kappa index for the proposed CA-Markov model was higher than 0.85 and the overall precision index was over 75%. It indicated that the model had a high-precision simulation effect and had a good performance in simulating the changes of woodland, cultivated land and water. 4) The variations of the land-use types in Poyang Lake region increased from 2010 to 2025, whereas their active levels had a stable trend. 5) The lost area of cultivated land and woodland was mainly caused by the gain area of the residential land from 2010 to 2025, the land-use change pattern performed a significant one-way transmission trend from other land-use types to the residential land. The regional urbanization accelerated obviously and urban expansion mainly distributed in the Nanchang-Jiujiang metropolitan area. 6) The lost area of grassland and the unused land mainly distributed in the boundary areas of the counties from 2010 to 2025. The regional urbanization had a positive effect on grassland protection, however, it is easy to cause the inefficient use of cultivated land and the woodland.
Key words：land-use change; Logistic regression; CA-Markov; Poyang Lake region

It is of great significance to clarify the interaction between industrial structure change and university outputs for promoting the optimization and upgrading of industrial structure and optimizing the development strategy of universities. Firstly, we use the improved cosine method and Theil index to measure the industrial structure change in Hubei Province.Then, on the basis of analyzing the defects and limitations of the existing evaluation indexes and measuring method of university outputs, we introduce a more rational measuring method to evaluate the university outputs. Finally, Grainger causality test, VAR model, Pulse response function and Variance decomposition are adopted to study the interaction between the industrial structure change and the university outputs in Hubei province from 2004 to 2013.The results show that 1) the advancement and rationalization of industrial structure are the Grainger reason for the education advancement. The technical market turnover and the graduates scale are the Grainger reason for the industrial structure rationalization; 2) the education advancement is able to respond to the impact of industrial structure change in a timely manner. The impact of the industrial structure rationalization on the innovation outputs is characterized by a response delay, whereas the impact on the graduates scale is not strong; 3) the advancement and rationalization of the industrial structure make great contribution to the education advancement. The contribution of innovation outputs to the industrial structure rationalization is much greater than that of the graduates scale.
Key words：industrial structure change; university outputs; Granger test; VAR model; pulse response

The urban agglomeration in the middle reaches of the Yangtze River promotes regional integration and builds a regional large-scale tourism consortium. This study identifies the spatial pattern of regional tourism development at present, evaluate the potential and trend of future tourism development, and construct a more optimized system of tourism development space in the middle reaches of the Yangtze River. Based on the multidimensional niche theory and the niche situation theory, the niche index system of regional tourism ecology, which can calculate the niche, the state and the potential, is constructed respectively. According to the niche situation model algorithm and the GIS platform, a map of regional ecological niche, potential, and comprehensive niche of tourism was drawn. The result shows:①Ecological niche, potential, and ecological niche of the highest and secondary ecological niche are all concentrated in Wuhan and Changsha regions.②Compared with the map of “state”, the map of tourism niche potential is more fragmented, reflecting the relatively complex development trend of regional tourism.③The general ecological niche of tourism has formed a regional area with Nanchang and Jingdezhen as the core, and a stretching area composed of Yichang, Xiangyang, Jingzhou and Yueyang.④There is significant spatial positive correlation between the value of “state”, the “potential” and the comprehensive niche, but the types of spatial agglomeration are different. Finally, according to the comprehensive ecological niche measurement results, the tourism development space system of the middle reaches of the Yangtze River is established, which includes “one nucleus lead, two pole drive, three axis tandem, four district support”.
Key words：niche theory; tourism industry; spatial structure; gis; city cluster along Middle Reaches of the Yangtze River

To explore the law of interaction between urban agricultural development and resources and environmental carrying capacity has great importance to promote the development of urban agriculture, solve the resource and environmental problems in urban development and promote the sustainable development of Nanjing. On the basis of scientifically constructing the evaluation index system of urban agriculture development and resources and environment carrying capacity, this paper uses the coupling degree model and takes Nanjing city as an example to make an empirical study on the coupling coordination relationship between them. The results show that the development level of urban agriculture and the carrying capacity of resources and environment in Nanjing have been increasing from 2000 to 2015. There is a positive correlation between each other. When the carrying capacity of the resources and environment is increased by 1%, the comprehensive evaluation value of urban agriculture in Nanjing is increased by 0.746%.The degree of coupling coordination is imbalance from 2000 to 2007, into the coordination stage from 2008 to 2015, is only 0.637 which in primary coordination in 2015. The type of coupling coordination is lagging behind the carrying capacity of resources and environment. Based on the foundation of resources and environment, Nanjing should scientifically plan the pattern of urban agriculture development; change the mode of resource development and environmental protection to ensure the sustainable development of urban agriculture; increase policy support to promote the collaborative optimization of urban agricultural development and resources and environmental carrying capacity.
Key words：urban agriculture; resources and environment carrying capacity; coupling coordination; Nanjing City

Water resource is an important economic resource and its use ratio is one of the important factors that affect the sustainable development of economic society. Researching the use ration of water resource of Wuhan urban agglomeration from 2005 to 2015 provides basis for the improvement of the area`s use ratio of water resources. The research takes water resource, capital and labor force as its input factors, economic effectiveness as the output factor and establishes the evaluation model on use ratio of water resource under the framework of total factor productivity. The study uses DEA-Malmquist model to investigate Wuhan urban agglomeration`s use ratio of water resource, input redundancy rate and total factor productivity, and makes use of linear regression model to analyze the influence of every breakdown index of total factor productivity on the use ratio of water resource. It turns out that the use ratio of water resource in Wuhan urban agglomeration is decreasing in earlier stage of research range; In 2015, the ratio increases, in this year, the input redundancy rate of water resource in non-DEA effective cities is on the high side overall speaking, the total factor productivity increases at first and then decreases, techch and pech have positive effects on use ratio of water resource, while the change of sech has a negative effect on it, therein the effect of techch on the use ratio is the most remarkable. Using DEA-Malmquist model, we can tell that the use ratio of water resource in Wuhan urban agglomeration is gradually increasing within the research range, and technology improvement can make the use ratio rise of urban agglomeration substantially. This model is able to provide a reference for the use ratio analysis of water resources in urban agglomeration.
Key words：DEA model；Malmquist TFP index；Wuhan urban agglomeration；utilization efficiency of water resources

Since the conventional evaluation coefficients of water resources environment system service function could neither reflect the ‘Binary-3D’ hydrogeology condition, nor indicate the influence of water environment on its service function, leading to a great deviation of evaluation result from reality. This paper combined the water environment with the karst development intensity to determine the correction coefficients in karst area. Then, the service function value for each city or prefecture was modified. The results showed that：(1) The main service function of water resources environment system in Guizhou province was ‘hydrologic storage & regulation and navigation’ and ‘environmental regulation & purification’, valued 789.22×108 and 742.66 ×108 yuan respectively, both of which account for 69.48% of the total value of the province. (2) the value of water resources environment system service function mainly depends on the supply & demand conditions of water resources, water area and the development of water tourism landscape. Moreover, the higher the utilization rate of regional water resources environment system is, the greater the value of water resources environmental system service function will be. The city of Guiyang possesses the maximum value of 292.65×108 yuan, while the city of Bijie displays the minimum value of only 74.35×108 yuan. (3) the correction coefficients were divided into water volume type, water quality type and mixed type, and the average values of these types were 0.81, 0.86 and 0.84 respectively, which were generally consistent with the characteristics of water cycle and water quality in different cities or prefectures. The above results indicated that the utilization of correction coefficients derived from development intensity and water environment to correct the evaluation results could not only highlight the influence of karst development characteristics on water resources and environment system service function, but also make the evaluation results more congruent with the real water ecological environment.
Key words：water resources environment; service function; evaluation; revise

Seasonal sampling of macrozoobenthos was performed in Dianshan Lake from 2009 to 2010 to explore the relationships of these organisms to carbon, nitrogen and phosphorus in the sediment and then assess water quality in Lake ecosystem. The benthic environmental quality was assessed based on the biotic and diversity indices of macrozoobenthos and the indices of sediment nutrients. A total of 17 macrozoobenthic species from 5 classes and 3 phyla, were identified. Heteromastus filiformis, Nephtys oligobranchia, Corbicula fluminea were the dominant species, with H. filiformis and N. oligobranchia making up 81.2% of the community density, N. oligobranchia and C. fluminea accounting for 75.0% of the biomass. The total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in the sediment was 7.91, 1.02, and 0.79 mg/g,respectively. There were no significant correlations between these biological and environmental parameters. The multivariable analyses indicated no spatial differences in the species numerical composition of macrozoobenthos; Significant spatial difference was only detected in TN with a non-parametric Friedman test (multiple paired samples analysis), among standing crop (density and biomass), diversity index (Shannon-Wiener diversity index ［H’］, Simpson diversity index ［D］, Margelef index ［ｄ］, Pielou evenness index ［Ｊ］) ,and sediment TOC, TN and TP . The correlation analysis showed that the standing crops were positively correlated with sediment TN, diversity indices were negatively correlated with sediment TP. The biological and sediment parameters indicated that Dianshan Lake was moderately to heavily polluted or mesotrophic to eutrophic. Dianshan Lake was characterized by low density of the whole community and oligochaetes and dominance of polychaetes and C. fluminea, which may be attributed to the sediment composition of the lake bed (silt and clay with low TOC concentrations) and its connection to the East China Sea by two short rivers.
Key words：Dianshan Lake; macroinvertebrates; sediment nutrients; community structure; water quality assessment

Climate change and intensive human activities had profound impacts on the global water circular system. As an important part in the water circular system, runoff changed significantly due to these two factors. Taking the Xitiaoxi Basin, which is located in the upper reaches of the Taihu Basin, as study area, the hydrological and meteorological trends in the Xitiaoxi Basin from 1972 to 2015 were analyzed by employing the accumulative anomaly, linear trend analysis and the flow duration curve method. Without considering the effect of evapotranspiration, the slope change ratio of cumulative quantity(SCRCQ) method and the climatic elasticity model were adopted to estimate the impacts of precipitation and human activities on the runoff change quantitatively. The main results were showed as follows: (1) A decreasing trend of annual runoff was revealed during 1972-2015 in the Xitiaoxi Basin. An abrupt change was identified around the year 1999, then the entire period was divided into two parts: baseline period (1972-1998) and variable period (1999-2015). The annual runoff in the Xitiaoxi Basin decreased by 11.76% or so after the occurrence of the abrupt change, which changed greatly. (2) The annual variation tendency of precipitation was not significant. Compared with the period before 1999, the annual average precipitation decreased by 1.43% during 1999-2015, which changed lightly. The runoff in the Xitiaoxi Basin was very sensitive to the change of the precipitation. The proportion of the flood season precipitation in the annual precipitation has been declining and the seasonal distribution of precipitation gradually became smooth, which contributed to the runoff decrease in the Xitiaoxi Basin to a certain extent. (3) According to the slope change ratio of cumulative quantity method, the contribution ratios of the precipitation change and human activities were 26.45% and 73.55% respectively, while the results obtained by the climatic elasticity model were 23.52% and 76.48%. The results of these two methods were close and indicated that human activity was the main factor that led to the runoff decrease in the Xitiaoxi Basin during 1972-2015.
Key words：runoff change; the slope change ratio of cumulative quantity; the climatic elasticity model; precipitation; human activities; contribution ratio

To explore the water pollution characteristics and causes of the Baima Lake, water quality data of 25 sampling sites in the lake were analyzed. The results indicated that the Baima lake water quality varied greatly in recent years. The lake water quality kept at class Ⅳ between 2010 and 2014, and improved to class Ⅲ in 2015, but decreased to classⅤ in 2016. The trophic level index (TLIc) of the Baima Lake showed a significant increasing trend, which changed from the lightly eutrophic level to the moderately eutrophic level (TLIc: 66.66) at present. During our sampling period, nitrogen was the major pollutant, followed by phosphorus and chemical oxygen demand (COD). The water pollution levels in the Baima Lake followed the order of north lake > east and central lake > south lake. Total dissolved nitrogen (TDN) accounted for 83% of Total nitrogen (TN) of the lake, and TDN composed of 65% ammonia (NH+4-N) and 25% nitrate (NO-3-N). Total phosphorus (TDP) accounted for about 60% of the total phosphorus (TP), and orthophosphate (PO3-4-P) occupy 55% of the TDP. The north lake part had the highest TDN/TDP mass ratios (50.51±19.16) (p<0.05) compared with other lake areas. Phosphorus was the limiting factor for algae growth in the north lake. However, the TDN/TDP in the central, east and south lakes was also favorable for algae growth. The terrestrially exogenous N/P inputs were the main cause for the spatial heterogeneity and water quality decline of Baima Lake. Furthermore, the degradation of ecological functions caused by hydrophyte destruction and aquiculture pollution in the lake might be another reason for the lake water quality declining. This work can provide data for the Baima lake water quality evolution and water environmental management.
Key words：water quality; eutrophication; TDN/TDP ratio; TLIc; Baima Lake

Water level, as a key hydrological factor of Poyang Lake, plays a crucial role in determining the hydro-dynamic process and water quality changes of the lake. Based on the monitoring data on water level and water quality of the main lake area of Poyang Lake and the dish-shaped sub-lake from 2014 to 2015, we examined the characteristics about the changes of the water level and major parameters of water quality within the year, and defined the characteristics about the response of water quality to water level. The results showed that: 1) during the wet season, the sub-lake is connected with the main lake area, and there is a linear correlation between water level of the sub-lake and that of the main lake area. During the dry season, the water level of the sub-lake is higher than that of the main lake area, the coefficient of variation for average monthly water level within the year in the main lake area was calculated to be 0.13, while that in the sub-lake was 0.08. 2) During the wet season, the N/P ratio in the main lake area and the sub-lake was recorded to be 19.29 and 46.27 respectively, while the figure was 17.88 and 40.39 respectively during the dry season. 3) The correlation between major water quality parameters and water level in the main lake area is significantly stronger than that in the sub-lake. The TN, NH3-N, TP and DO are found to be negatively correlated with water level in the main lake area, while there is only a correlation between pH and water level in the sub-lake. 4) During the dry season, the content of TN is high in the sub-lake, while that of TP and NH3-N is high in the main lake area. Overall, these results imply that optimizing water level management during the dry season can help effectively reduce the risk of eutrophication of Poyang Lake.
Key words：water level; water quality; dish-shaped lake; Poyang Lake

Monitoring and assessing eutrophication of lake water are basic work, which is important for water resource management and water environment protection. Based on GF-1 WFV images,82 measured data and the method of trophic level index, we built the multiple linear regression model and RBF neural network model, and we got the trophic level index of lakes in Wuhan and its surrounding areas. The inversion result shows that most lakes are in a state of light eutropher and mesotropher, and the partial in middle eutropher. The results show that GF-1 WFV multispectral images are feasible in monitoring the water quality of numerous lakes; we can retrieve the trophic level index and dynamically monitor water quality with functions established by measured data and remote sensing information; the RBF neural network model has a R2 of 0.742 3 and a root mean square error of 3.72. The inversion accuracy of RBF is higher, which is more suitable for monitoring the change of water quality in inland lakes.
Key words：Wuhan; the inversion of lake water quality; trophic level index; GF-1; RBF neural network

Through fieldwork and water sample monitoring, the application of BP neural network model, evaluation method of lake eutrophication and ShannonWeaver index, the study separately evaluated the water environment quality, nutrient level and aquatic life status of Dongting lake before and after the impounding of The Three Gorges Project in typical years (1986,1991,1998,2004,2006 and 2010).The results indicate that after the impounding of the Three Gorges Reservoir, the water environmental quality get worse as a whole, the overlimit ratio of the water quality of all its sections has a significant increase and it presents mainly to N,P accompanied with organic pollution. The Nutrient index has risen.The comprehensive nutrition index of east Dongting Lake from 2008 to 2010 exceeded 50 and became Mild eutrophication. Cryptophyta has replaced bacillariophyta and becomes the dominant species of phytoplankton in Dongting Lake, where its biodiversity index has descended. The dominant species of zoobenthos is bellamya purificata in east Dongting Lake while branchiura sowerbyi in the west and south Dongting, whose species and density tend to fluctuate downward. The factors affecting the water quality of Dongting lake are not only the “three ports”, “four waters” pollutants, but also the pollution of the lake area and nonpoint source pollution, the crucial reasons are the great reduction of the amount of sediment in the lake and the change of land use pattern.

The consistency of hydrological sequence might have been changed by human activities and climate change. The daily data in flood season of 6 rainfall gauges during the period of 1963 to 2013 was addressed to analyze the consistency of rainfall-runoff in the upper Huanhe river. The Mann-Kendall rank statistic test and Pettitt change-point statistical methods were applied to trend and abrupt change test in terms of 1 day, 3 days and 7 days. Then the spatial and temporal distribution change of rainfall was quantified with non-uniform coefficient and a gravity center model. The runoff change pattern of different relative duration was analyzed using daily flow duration curve. Finally, the temporal variation of rainfall-runoff relation was explored. The result indicated that the rainfall showd a nonsignificant trend of decrease and non-obvious change in spatial distribution, while the rainfall gravity center mainly located between Guangshui station and Caodian station.The runoff in Huayuan station assumed the reduced tendency, while the maximum average flow in 1 day, 3 days and 7 days have declined significantly. The downward trend of high flow and upward trend of low flow was obvious. The deviation between high flow and median flow reduced, similarly with the deviation between low flow and median flow. The average decline rate of rainfall and runoff was 11.6 mm/10 a、20.8 mm/10 a over the years while the runoff coefficient in flood season descended. The runoff coefficient and runoff had a piecewise linear relationship with the break point of 565 mm for rainfall.
Key words：spatio-temporal evolution; spatial non-uniformity; rainfall gravity center; flow duration curve; rainfall-runoff relationship

In recent years, due to the dual impacts of climate change and human activities, the annual runoff of the Chongqing section of the upper reaches of the Yangtze River decreased significantly. In this paper, the MASH moving average method was used to analyze the runoff variation characteristics at three main hydrological stations in Chongqing ：Cuntan, Beibei and Wulong. Further, the elastic coefficient method, together with the regression analysis method was adopted for runoff simulation, in an attempt to evaluate quantitatively the contribution rates of climate change and human activities on runoff change. The results showed that: (1) the contribution rates of climate change and human activities to the annual runoff reduction at all three hydrological stations were about 25.2%~35.2% and 64.8%~74.8%, respectively for the period of 1991-2011, compared to the reference period of 1961-1990. (2) The impact of climate change on monthly runoff is limited. Consequently, runoff in July increased to a certain extent, and runoff in August to October generally reduced. The influence of human activity was obvious, leading to a slight increase in runoff from December to April and runoff reduction from May to November. (3) Both methods indicated that human activities were the major factor causing runoff reduction. Quantitative assessment of the causes of runoff changes helps formulate scientific countermeasures and coordinate the development and utilization of water resources in the upper reaches of Yangtze river.
Key words：climate change; human activity; runoff change; quantitative attribution; Chongqing

Based on the runoff data of the Three-River Headwaters Region (TRHR) between 1960 and 2009, numerical analysis was coducted through the digital filter method, and the Depuit-Boussinesq equation was used to calculate the recession coefficients. At the same time, the Mann-Kendall trend test method was used in runoff trend analysis. The results showed that: (1) In the past 50 years, discharge of the Yellow Rivers Headwaters Region (YERHR) and the Lantsang Rivers Headwaters Region (LARHR) significantly decreased, but no obvious discharge change was found in Yangtze Rivers Headwaters Region (YARHR). (2) The runoff of the dry season in the TRHR was mainly controlled by the base flow. The ratio of the base flow to the winter runoff could be up to 100%. Base flow of YERHR and LARHR were declining in past 50 years, and Their variation trend and the sudden change point of the base flow are consistent with the runoff. (3) Upon the climate change effects, precipitation was the main factor that influenced runoff and recession processes in TRHR. The precipitation increasing of could lead to the decrease of the recession coefficient, while the influences of temperature on the water recession processes in TRHR were uncertain. This study provides a theoretical reference for the evolution of the TRHR runoff processes responding to climate change.
Key words：Three-River Headwaters Region; recession coefficient; baseflow separation; Mann-Kendall Trend Test

The paper selected the daily data of maximum and minimum temperature from the 13 meteorological stations in the Jiangsu Province, and explored the trend and probability characteristics based on linear trend estimation, improved Mann-Kendall trend and abrupt change test and GEV model; Moreover, the spatial characteristics of extreme temperature with the return period of 100 years are also investigated based on ARCGIS. The results indicate: (1) For the indices measured by maximum temperature, ice days and cool days show negative trend; summer days and warm days show positive trend. For the indices measured by minimum temperature, frost days and cool nights show decreasing trend; tropical nights and warm nights show increasing trend. (2) The upward trend of extreme minimum temperature is weaker than that of extreme maximum temperature based on the improved Mann-Kendall test. The abrupt years are mainly during the 2000s for extreme maximum temperature, and they are mainly during the 1980s for extreme minimum temperature. (3) The return levels for extreme maximum and minimum temperature were obtained using the stationary and non-stationary GEV models. The return level obtained by the non-stationary GEV model change with the trend of the original time series. (4)The spatial patterns of extreme maximum temperature for return level of 100 years increase from the west to the east, and those of the extreme minimum temperature decrease from the northwest to the southeast.
Key words：extreme maximum temperature; extreme minimum temperature; improved Mann-Kendall test; probability characteristics

In this study, the hygroscopicity of submicron particles was studied from September to October in Mt. Huangshan. A Humidity Tandem Differential Mobility Analyser (H-TDMA) instrument was applied to measure the hygroscopic growth factor (GF) at different altitudes for particles with dry diameter between 40-200 nm. The statistical results show that, the GFs of the aerosol show a distinct bimodal distribution, and classified into less-hygroscopic (LH) group (GF＜1.15)and more-hygroscopic (MH) group(GF＞1.15). The spread of GF-PDF (σ) are higher in more-hygroscopic group than in less-hygroscopic group with the same size. The change of relative humidity has an effect on particle hygroscopic growth which is associated with particle size and chemical compositions. Aitken nuclei and condensation nuclei have different deliquescence point under the same relative humidity. The main moisture absorption components are ammonium nitrate and ammonium sulfate. Mt. Huangshan is clean and pollution emission source is unitary. the experiment set relative humidity is 85% which is lower than in other places. So the hygroscopicity is less than in the city area. By comparing the hygroscopic growth factor of aerosol particles under the different altitudes, it is found that with increasing altitude, hygroscopicity of particulate matter is reduced.
Key words：aerosol particles; hygroscopic growth; H-TDMA; Mt. Huangshan

The transboundary air pollution has lead to serious public health issues in Asia. It is necessary for Asian countries to corporate with each other in the governance of air pollution. Based on the current pollution situation, this article collects the cooperation framework, program, fund raising, and information communication in Asia region, and analyses its weakness. In addition, by evaluating the collaboration mechanism in North America and European Union, this article aims to learn from their experiences and made the following recommendations：(1)  integrate the cooperation framework for the control of transboundary air pollution in Asia;(2) optimize the management system of cooperation and control over transboundary air pollution in Asia;(3)enhance the transboundary air pollution data and information exchange in Asia;(4) expand the scope of cooperation projects in the air pollution control in Asia;(5)intensify the non-governmental cooperation in the prevention and control of transboundary air pollution in Asia;(6) increase investment in low-carbon and air pollution control projects in Asia.
Key words：Asia；transboundary air pollution ；international cooperation mechanism

Soil and water samples (3 246 soil samples and 78 water samples) were collected to study characteristics of soil salinity and indicative significance of soil salinity. Research shows that the degree of soil salinity is parallel to the coastline. The closer to the sea shore, the high content of salt is soil. Salt in the soil is mainly from four different sources: seawater immersion in the soil sedimentary process, the original salt in the sediments, the modern salt deposition in near surface soil, and the influence of human activity. The seawater immersion is the main reason to increase the soil salt content. Through Na-Cl exchange process, the formation mechanism of saline soil was analyzed in the water and soil system. Original salt in the sediment was analyzed by the scale factor method. A series of linear regression prediction models were established between the soil soluble salt contents of the well positions and the TDS. The regression between the Cl- in soil and the TDS was the most significant. This is related to that Cl- is a stable element and susceptible to soil adsorption. The regression prediction models were validated by HYRD1 well, and the accuracy was 96%. Taking HYRD1 well as an example, this paper explained the soil salt content role in multiple stratigraphic divisions based on the characteristics of littoralfacies sedimentary layers.
Key words：soluble salt; chlorine saline soil; regression analysis; TDS

This paper calculated ecological footprint of Jiangsu province between 2005 and 2015. An ecological footprint decomposition model was built based on logarithmic mean divisia index (LMDI) method. The influences of land structure, technology, economy and population on ecological footprint changes were analyzed. Additionally, the differences among the main factors influencing the ecological footprint in Jiangsu province were calculated using the Gini Coefficient, Logarithmic Mean Deviation and Theil Index. The results showed that the ecological footprint in Jiangsu increased from 2.82 ha per capita in 2005 to 3.88 ha per capita in 2015 with an annual increase rate of 3.24%. Changes in land structure, rapid economic development and population growth had promoted the growth of ecological footprint. The improvement of science and technology could inhibit the consumption of natural resources. Technical level and economic level were the main factors affecting the change of ecological footprint in Jiangsu province. The overall differences within Jiangsu province had been decreasing over time, while there were significant difference among Southern Jiangsu, Central Jiangsu and Northern Jiangsu in terms of technical and economic effects. Therefore, it is necessary to strengthen the coordinated development of Southern Jiangsu, Central Jiangsu and Northern Jiangsu to promote technological learning and economic complementary.
Key words：Jiangsu province; ecological footprint; impact factors; regional difference