In many regions non-point source pollution has been the primary contributor to surface water pollution. Thereby,how to effectively reduce the nitrogen and phosphorus discharge from non-point source has become one of the important scientific issues. Periphytic biofilm (also known as periphyton) is a kind of microbial aggregates growing on the surfaces of submerged solids and being intertwined with surrounding abiotic matters. Periphytic biofilm is common at the soil and water interface,with strong adaptability to the abiotic environment and capability of removing pollutants from water. In recent years,periphytic biofilm has gained wide attentions in wastewater treatment and remediation of natural water bodies. In this paper,the nitrogen and phosphorus removal mechanisms,such as denitrification,ammonia volatilization and stripping,assimilation,adsorption and precipitation of phosphorus,as well as the latent factors driving these processes are summarized. Besides,the recent advances in nitrogen and phosphorus removal by coupling periphytic biofilm with new functional materials are also summarized. Finally,the applications of periphytic biofilm combined with ecological engineering to large-scale non-point source wastewater treatment and ecological restoration are proposed. This study will provide a theoretical reference for the wastewater purification by periphytic biofilm and similar microbial aggregates,as well as for the regulation of periphytic community structure and its functions.

With the accelerating progress of urbanization,all kinds of ecological problems have become increasingly prominent;ensuring ecological security and constructing ecological civilization have thus become important in the context of current social development. This study proposes a source evaluation system that couples the ecological needs of residents of Guangzhou,based on "people-oriented" thinking in the construction of ecological civilization. The minimum cumulative resistance model and the resistance surface were then jointly corrected based on the nighttime light index and the impervious surface index to identify the ecological corridor network. Finally,the ecological security pattern of Guangdong Province based on the ecological components was constructed. The results show the high degree of importance of the ecological land in Guangdong Province,accounting for 61.17% of the total area,of which the ecological source area accounted for nearly half,amounting to 29.59% of the total area. The key ecological corridors,together with the potential ecological corridors and the existing corridors,have jointly built a spider web-style radiation distribution network with "one areamulticorridors-two protections". The validity of the pattern construction was verified through the nature reserve data,and the resistance surface of multi-variable data co-correction was found to be more appropriate. The ecological security pattern of Guangdong Province can be ensured by focusing on pollution control,ecological restoration,and ecological source areas maintenance. The protection of ecological sources and ecological corridors should be prioritized. The secondary ecological land around the built-up areas can be prioritized for the construction of public ecological service facilities and reducing the high-intensity ecological needs of the central city.

The western region is the main agglomeration area of mineral resources in China. Quantitative evaluation of energy competitiveness and energy service function in the western region and concrete research of energy flows between energy cities and consumer cities are very important for regional coordinated development. In view of this,the urban flow intensity of the western provinces and the city energy flow gravity intensity between the energy city and the energy consumption city are measured through the urban flow and gravity model. The main conclusions are as follows:(1) Shaanxi Province is the core region of western provinces with the highest intensity of urban flow and the strongest external service function to surrounding provinces and regions. Shaanxi Province also ranked the second in comprehensive energy competitiveness; (2) The Inner Mongolia Autonomous Region and the Xinjiang Uygur Autonomous Region are the regions with strong comprehensive energy strength in western provinces and regions; (3) Yulin,Ordos and Xianyang have the highest energy supply potential and can be used as the main energy supply cities in China; (4) Heavy industrial cities with large energy demand should become the priority supply areas of energy cities,followed by municipality directly under the central government and central cities of China's urban agglomeration; (5) The three northeastern provinces,as well as Guangzhou,Haikou and some other areas had weak gravitation to energy cities because they are far away from the central energy source area. These places should pay more attention to the development of new energy to meet their own development needs.

The improvement of agricultural green total factor productivity (GTFP) is the key to the construction of ecological civilization. Taking 142 counties in Hebei Province as research objects, non-radial,non-angle,slacks-based measures (SBM) directional distance function and the global Malmquist-Luenberger (GML) index were used to measure agricultural GTFP at county level in Hebei Province from 2000 to 2016,and spatial autocorrelation methods were used to analyze the global and local spatial characteristics of agricultural GTFP in Hebei Province. Research results show that:In average,the agricultural GTFP increased by 5.42% annually from 2000 to 2016,which was mainly driven by the advancement of green technology. If environmental factors were considered,the agricultural "Porter ‘win-win’ hypothesis" may be realized. From the perspective of regional distribution,there was a regional unbalance in the growth of agricultural GTFP in Hebei Province. The growth level of Northern Hebei Province was higher than the average level of the province, while the growth levels of Central and Southern areas of Hebei Province were lower than the average level of the province. There was a significant spatial correlation between agricultural GTFP at county level in Hebei Province,but spatial correlation was weakening. The agricultural GTFP showed obvious geographical agglomeration characteristics in Hebei Province. The hot spot area expanded to Central and Southern areas of Hebei Province,and the cold spot area was transferred from the one wing to the two wings of Northern Hebei Province.

By quantitatively studying the response of Populus euphratica population growth and plant diversity to flooding irrigation in lower reaches of Yarkant River basin,a theoretical basis for optimizing water resource management regulation and ecological protection practice in Yarkant River Basin is provided. From 2016 to 2018,Three visits were paid to the lower reaches of Yarkant River to obtain vegetation survey data,and to analyze the response of Populus euphratica population to flooding irrigation with the aid of Pielou index,Shannon-Wiener index,Simpson index and important values. The results show that after 2 a of flooding irrigation the Simpson index,Shannon-Wiener index and Pielou index increased by 124.8%,119.6% and 246.9% for Populus euphratica forest in lower reaches of Yarkant River,respectively,and 12 new species of hygrophilous and annual herbaceous plants were found,and vegetation coverage rate was 42.5%,increased by 112.5%. Populus euphratica forest in the study area were medium aged,growth of Populus euphratica did not deteriorate,growth of Populus euphratica forest above medium grade increased by 3.9%,and the height under the crown of Pop-ulus euphratica decreased by 7.7%. With the increase of distance from ecological gate,plant density and diversity had a decreasing trend,but 450 m distance from ecological gate the plant diversity and plant density was significantly higher than that of the plants with 150,300 and 600 m from ecological gate (P<0.05). The dominant species at 150 and 300 m in distance to the ecological gate were annual herbaceous and hygrophilous plant such as Sophora alopecuroides and Phrag-mites australis,etc. Outside the range of 450 m in distance the dominant species were Populus euphratica,Tamarix ra-mosissima and drought-tolerant perennial herbaceous. The 2 a flooding irrigation project ended the tendency of Populus eu-phratica forest degradation,and significantly improved plant diversity and vegetation coverage. At the same time,plant community of desert riparian forest has enhanced its ability to renew within 450 m in distance to the irrigation gate,and biodiversity has been protected. In order to maintain current trend of ecological improvement,flooding irrigation projects should be continued.

The most pervious study about the priority evaluation of the reclamation of industrial and mining wasteland into forest land only considered its suitability for forest land,and took less consideration of its contribution to forest landscape connectivity. Taking Daye City in Hubei Province as a case study,the priority degree of ecological reclamation in industrial and mining wasteland evaluated by fuzzy comprehensive evaluation method,landscape connectivity index and two-dimensional method. The results show that:(1) the areas of the most suitable,more suitable,less suitable and unsuitable patches of the reclamation of industrial and mining wasteland into forest in Daye City were 967.44,343.54, 67.85 and 75.96 hm². The most suitable patches concentrated in Jinshan Town,and the unsuitable patches mainly distributed in the Huandiqiao Town. (2) The optimal distance threshold of landscape ecological network connection is 1 250 m in Daye. After the reclamation of industrial and mining land,the area of the highest,high,middle and low-grade patches contributing to the ecological network structure of forest land were 234.80,358.24,315.08 and 546.68 hm²,respectively. (3) The area of priority of ecological reclamation of industrial and mining waste land in Daye City were 403.68,408.52,594.65 and 47.90 hm² for grade Ⅰ,Ⅱ,Ⅲ and Ⅳ,respectively. The results of fuzzy suitability evaluation were different from those of network structure importance evaluation. The results of the study can avoid considering only one-sidedness of the evaluation results and enhance the consideration of ecological effect to make the evaluation results more reasonable.

By considering the coupling of landscape patterns and space,the evolution of landscape patterns in Tarim Ba-sin was studied through analyzing multi-source remote sensing images. The influence of landscape pattern on carbon bud-get was also investigated in this study. The results show that:(1) The vegetation condition in Tarim Basin becomes better due to the positive influence of climate change and human activities. The woodland area and the cultivated area both sig-nificantly increased while the grassland area slightly increased; (2) The carbon budget in Tarim Basin is in good condi-tion with carbon sequestration. Its capacity gradually increased from 2001 to 2010; (3) Although current human activi-ties including sand prevention and carbon fixation,water delivery,and water conductivity improved the ecological envi-ronment in Tarim Basin,further ecological management should be carried out considering climate change impacts.

The soil respiration rate (R_s) and its influential factors of two green landscapes (GL and YZ) were measured using a portable automated CO₂ exchange station (ACE) during the whole growing season in Tianjin. The relationships be-tween soil respiration and its influential factors of soil temperature,soil moisture and soil physicochemical properties have been analyzed. Results show that:(1) There was basically no difference in the seasonal variation of R_s between the two different types of green landscapes,both of them showed an obvious single-peak variation and the peak appeared at the same time. Simultaneously,the variation of R_s was different in different months. In dry season,the R_s was low with few fluctuations,which ranged from (0.20±0.03) to (1.09±0.16) μmol·m^-2·s^-1 for GL,and from (-0.06±0.01) to (0.26±0.05) μmol·m^-2·s^-1 for YZ. Conversely,a relatively higher R_s with more fluctuations was noted in the wet sea-son,it seemed to be varied from (-0.05±0.01) to (3.62±0.26) μmol·m^-2·s^-1 for GL,and from (0.38±0.07) to (3.17±0.27) μmol·m^-2·s^-1 for YZ. In summary,the mean value of R_s in GL was significantly higher than that in YZ; (2) The environmental factors that influence R_s are very complicated in the two green landscapes. The two relatively im-portant factors are soil temperature at 10 cm depth (T₁₀) and soil moisture at 5 cm depth (M₅). In addition,the regression analysis show that the effective degree of T₁₀ and M₅ for R_s were 45.4%-64.8% and 21.1%-52.2%,respectively; (3) There was a certain correlation between soil physicochemical properties and R_s,in which the correlation coefficient between soil organic matter and R_s was highest in all the two green landscapes.

Plant growth-promoting rhizobacteria (PGPR) can secrete plant growth hormone and promote soil nutrient cir-culation,which is an important germplasm resource of biological fertilizers. Adsorption of PGPR to crop roots is a neces-sary condition for colonization and function,and drug resistance marker is a mean of studying the ability of functional strains to colonize and promote growth. The purpose of the experiment is to label the strain by the antibiotic drug rifampi-cin,and to study the retention of the function of the strain,and then to determine the colonization survival ability of the strain in the rhizosphere of rice. The results show that the adsorption of rice roots to strain increased with the immersion time,and the adsorption content of K-LZP01 was basically stable after dipping for 10 min. K-LZP02 reached the maximum adsorption capacity at 50 min. The maximum adsorption capacity of K-LZP03 was 12×10₇ CFU·g_-1 at 5 min,and then be-came stable. When the rice seedlings were dipped in different concentrations of bacterial suspension, the adsorption capac-ity of radicle increased with increasing of bacterial suspension concentration. After 10 days of inoculation in soil,the colo-nization quantity of the labeled strains tended to be stable and the colonization ability is strong. The results found that the closer the distance to the rice rhizosphere,the higher the strain content,which indicate that the strains had good coloniza-tion competitiveness. In both sterilized and unsterilized soils,the three strains could all promote the growth of rice. In this study,researches on the resistance marker of PGPR strain as well as its colonization and growth promotion in rice rhizo-sphere were carried out,and the results are important to interpret the mechanism of PGPR and guide the production prac-tice.

In order to investigate the physicochemical properties of biochar at different pyrolysis temperatures and under-lying adsorption mechanism of Zn²⁺ on biochar. Crayfish shell biochar were prepared at 300,400,500,600℃ by the limited oxygen slow pyrolysis (LS300,LS400,LS500 and LS600). The original biochar and zinc-loaded biochar were char-acterized by using scanning electron microcopy with energy spectrum analysis (SEM-EDS),Fourier transform infrared spectroscopy (FTIR) and X-ray diffraxtion (XRD). Then,the Zn²⁺ adsorption property and mechanism of crayfish shell biochar was proposed based on the results of adsorption experiment and characterization. Results indicated that the higher the pyrolysis temperature,the yield of crayfish shell biochar decreased,while the ash content,pH,the pore diameter, and the aromaticity were increased. The adsorption kinetics was well fit to the pseudo-second order model. For LS600, adsorption equilibrium was reached at 7 h,and adsorption equilibrium of the other three types biochar were reached at 24 h. The isothermal adsorption of LS600 was well consistent with the Langmuir isotherm model,and LS600 displayed the best adsorption effect on Zn²⁺,with its adsorption rate up to 462.50 mg·g_-1. Isothermal adsorption of LS300,LS400 and LS500 were well described by Freundlich isotherms model. The adsorption mechanism of crayfish shell biochar on Zn²⁺ mainly includes cation exchange,the surface complexation of oxygen-containing functional groups,the combination of π electrons and precipitating action.

Coal mining has an important impact on the surrounding rainfed farmland. In order to clarify the effects of coal mining on soil nutrients and heavy metals content in arid grassland area,the soil nutrients (organic matter,total N,total P,total K and pH) and heavy metals (Pb,Cd,Cr,Cu,Zn,Ni,Hg) were measured in the rainfed farmland around Dingjiagou Coal Mine in Yijin Holuo Banner,Ordos City. The relationship between soil nutrients and heavy metals and the sources of heavy metal pollution were analyzed. The results show that coal mine had a great influence on soil nutrient and heavy metal content in 0-10 cm rainfed farmland around the mining area,and caused the decrease of organic matter and total N content in soil;in the range of 500 m around the coal mine,the contents of heavy metals Cu and As in soil were higher than CK;in the range of 2 500 m around the coal mine,the contents of Pb and Cr in soil were higher than CK. Soil organic matter and total N contents were lower than those of CK at 1 250 m range around the coal mine,and were negatively correlated with the contents of Pb,Cr,Cu and As in the soil;Zn mainly came from transportation;Ni mainly came from agricultural production activities;Cd and Hg came from natural soil parent materials and anthropogenic activity outside coal mine. Therefore,the pollution of Pb,Cr,Cu and As from coal mines should be controlled when the rainfed farmland in this area is to be protected.

In order to comprehensively understand the concentrations and spatial distribution of polycyclic aromatic hydrocarbons in surface soils in China,208 literatures published from 1999 to 2018 on PAHs in the surface soils were collected for data extraction and in-depth analysis. ArcGIS spatial interpolation technique,geographic detector model and statistical method were used to quantitatively analyze the concentration,spatial distribution,main sources,and affecting factors of PAHs in the surface soil in China. The results show that the spatial distribution of PAHs in the surface soil has obvious spatial variation. The PAHs concentrations follow a significant decreasing trend of north China > northeast China > east China > mid-south China > northwest China > southwest China. The average concentration of 16 USEPA priority PAHs in north China is about 2.5 times that of southwest China. The PAHs pollution level in the surface soils in China generally ranged from low to medium according to Maliszewska-Kordybach's classification standard. The moderately polluted, slightly polluted,and uncontaminated soil accounted for approximately 22.6%,71.1% and 6.3%,respectively. Quantitative analysis of nine socio-economic factors by using geo-detector model shows coal-fired power generation is the most significant factor on PAHs spatial distribution compared with the other factors. Principal component analysis also indicates that the coal combustion is the important pollution source,in consistent with the result of geo-detector model. This study has certain reference value for the prevention and scientific control of PAHs pollution in the surface soil in China.

Land use in riparian zones is an important factor affecting river water quality. Data of 10 water quality indicators for 2013 were collected from 55 river network water quality monitoring stations in Shanghai. Based on the data,the self-organizing map was used to identify the spatial distribution pattern of water quality in the city. Moreover,the redundancy analysis (RDA) and Spearman rank correlation analysis were used to investigate the relationship and scale effect between water quality and riparian land use (100,200,500,1 000 m buffer). The results show that:(1) The 55 water quality monitoring stations in Shanghai could be divided into 4 clusters,which reveals an evident spatial heterogeneity. The cluster I composed of monitoring stations in the outer suburbs,including Dianshan Lake and Chongming Island,represents the best water quality. Comparatively,water qualities of cluster Ⅱ distributed along the Suzhou River and cluster Ⅲ in the suburbs of the city are poor. (2) Among all the spatial scales,the 500 m buffer has the strongest total interpretation of clusters Ⅰ,Ⅲ,and Ⅳ,and the 1 000 m buffer has the strongest total interpretation of cluster Ⅱ. (3) On the optimal spatial scale,urban construction land has a high interpretation rate for water quality of each cluster,and is positively correlated with most of the water quality indicators.

Dissolved organic matter is an essential effect on the conversion exchange between organic matter and inorganic matter in nature environment, which is widely distributed in water,soil and sediments. As a pollutants carrier,it affects the migration and transformation of contaminants,while it also provides carbon source and nutrients for microorganisms. For exploring the composition, source and humification degree of DOM in Moguhu Lake,the components of DOM in the overlying water was analyzed by using three-dimensional fluorescence spectroscopy combined with parallel factors. The source and humification degree were studied by means of spectral index (FI, HIX, BIX), and the correlation and relationship between FI and F_max were used to explain the type and characteristics of DOM. The results show that in Moguhu Lake,DOM of overlying water contains four components, which are two represent fulvic acid substances for C1 and C4, tryptophan in the protein C2 and humic acid C4. Secondly,the DOM is mainly composed from microbial endogenous metabolites with high bioavailability and low degree of humification. Positive correlation was found between each component F_max and FI,and a significant positive correlation existed between fulvic acid and FI. According to previous studies, in Moguhu Lake,the primary component of DOM is fulvic acid-like substance,which contains a reactive functional group such as a carbonyl group or a hydroxyl group with small molecular,and with characteristics of a low degree of humification,aromaticity,and low molecular condensation.

Taking the opencast mine of grassland as an example,comparison was made on the physical properties of soil bulk density,soil moisture content,soil gravel content and soil texture in the reclaimed land of south and north dumps and the undamaged land of the Shenhua Beidian Shengli Opencast Mine. The methods of variance analysis and fitting analysis were adopted to analyze the differences in physical properties of reclaimed and undamaged soils and the reasons for the dif-ferences. The results show that:(1) Soil bulk density,soil moisture content and soil gravel content in the 8-year reclaimed north dump and the 4-year reclaimed south dump are higher than those of in the undamaged land,while the soils of the south dump and the undamaged land are sandy loam,and the soil of the north dump is sandy clay loam. The fitting analysis shows that the soil bulk density and soil moisture content were affected by soil gravel content and soil texture. (2) With the extension of the reclamation years,soil bulk density,soil gravel content and sand content of soil texture showed a decreas-ing trend,while soil moisture content,silt content and clay content showed an increasing trend. With the increase of soil depth,soil bulk density,soil moisture content,silt content and clay content showed an increasing trend,while soil gravel content and sand content showed a decreasing trend. (3) In general,the soil physical properties of the 8-year reclaimed north dump are better than those of the 4-year reclaimed south dump,which is closer to the undestroyed land. Soil mois-ture content of the >20-40 cm soil layer was significantly higher than that of the 0-20 cm soil layer,which indicates that coal gangue has good water retention capacity. It is an ideal soil reconstruction model using of topsoil and coal gangue to construct the soil profile for land reclamation in the grassland mining area where the topsoil is scarce.

To investigate the effects of irrigation modes on biomass,biomass allocation,corn yield and water use efficiency of sweet corn,a field experiment including full drip irrigation without plastic film (T1),full drip irrigation under plastic film (T2) and drip irrigation with limited soil moisture under plastic film (T3) was conducted. The results show that irrigation modes had no significant effects on the biomass of sweet corn,but affected the allometric scaling relationships between different organs. The scaling exponents of stem mass vs total plant mass and leaf mass vs total plant mass for T3 were lower than those for T2 and T1. The scaling exponents of root mass vs total plant mass for T1 were lower than those for T2 and T3. The vegetative organ were isometric with the reproductive organ for T2 and T3,indicating that the growth rate of reproductive organs was proportional to the growth rate of vegetative organs. The scaling exponents of vegetative organ vs. reproductive organ for T1 was lower than 1,indicating that the growth rate of reproductive organs scaled allometrically with the growth rate of vegetative organs. The scaling exponents of underground vs. aboveground biomass for T1 were lower than for T2 and T3. Drip irrigation under plastic film increased the allocation biomass toward stem,leaf, aboveground and reproductive organ compared to the other treatments. Under the equivalent production,T2 and T3 saved water by 26% and 44%,and improved water use efficiency by 0.65 and 1.43 kg·m^-3 compared to T1,respectively. Drip irrigation with limited soil moisture under plastic film (the lower limit of relative soil water content is 70%, the upper limit is 90%) is a water-saving and efficient irrigation mode of sweet corn in Yuanmou dry hot valley.