Result summaries and theoretical sublimation were made on the basis of researches, applications and practices in the field of environmental green remediation in the past two decades. At first, the new insight of "hyper-accumulative or remediation plants also occur in non-polluted areas" was put forward through a large number of practices, and a new method of mutual corroboration for screening out hyperaccumulators or remediation plants between clean areas and polluted areas was constructed and verified, on the basis of having supplemented and perfected the criteria for identifying and determining hyperaccumulators or remediation plants. Moreover, the theory of interaction between plants and environmental media based on the formation and growth of hyperaccumulators or remediation plants and the mechanisms of eco-pattern optimization and comprehensive strengthening of environmental remediation are further proposed, on the basis of having clarified the interaction relationship between hyperaccumulation/remediation plants and soil. This progress has undoubtedly laid a theoretical foundation for further development and extensive practice in this field in the future, and pointed out the direction of future development.

Invasive alien species are major threats to biodiversity around the world, and China is one of the countries that suffers from the most severe invasions of alien species. The definition of invasive alien species is a controversial topic, yet the first step in preventing and controlling invasive alien species is to accurately define them and clear control objects. In this paper, the methods used for defining invasive alien species in various conventions and in different countries and regions are comprehensively analyzed. The main challenges of defining invasive alien species in terms of expression, spatial scope, time range, influence, and hierarchy are then discussed. By analyzing the concept and connotation of invasive alien species, the important issues surrounding invasive alien species are explored and new reference ideas are provided for lawmakers working on prevention and control policies.

Research advancements in soil environmental quality evaluation of agricultural land in China and other countries were reviewed. The evaluation standards and evaluation methods as well as the category classification were analyzed. From different evaluation scales of monitoring points, investigation unit and evaluation unit, and based on the degree of exceeded standard, cumulativity and security of agricultural products, the soil environmental quality evaluation procedure and methods of agricultural land were described in detail. Based on the multi-source data and multi-dimensional evaluation, the applicability of methods for category classification of soil environmental quality of agricultural land are discussed and presented for current soil management in China.

The ecological habitation fragments in the traditional mining city is severely fragmented. Reconstructing the ecological networks is greatly critical to the improvement of the regional ecosystem services, as well as the maintaining of biodiversity and landscape diversity. For the reconstruction of the ecological safety network of Xuzhou City, morphological spatial pattern analysis (MSPA), and landscape index were used to extract the ecological sources with great value for the maintenance of urban ecosystems health. Then, the minimum cumulative resistance model (MCR) was used to build ecological resistance surfaces and extract the potential ecological corridors. Circuit theory combined with the graph theory and network structure analysis were used to quantitatively evaluate and optimize the ecological network. The results show that there are 237 ecological sources, mainly distributed in the southwest part of Xuzhou City, with a total area of 6 421.49 hm². However, additional 70 small ecological habitats and 192 ecological corridors should be added to make up the deficiencies of current ecological network. The reconstruction of ecological network could obviously reduce the landscape fragmentation and patch separation, and increase the patch connectivity and adhesion degree, and as a result the regional landscape pattern and ecological security will be improved. This research could provide scientific reference for the transformation of the traditional mining cities, and redevelopment of inefficient land, as well as land space planning.

Research on the eco-environment vulnerability assessment is an important basis for the regional ecological environment restoration and governance. Based on the interaction between man-made and natural factors, 14 indices were selected which can represent the human activities, social economy, vegetation, meteorology, soil and terrain landforms to construct the ecological vulnerability evaluation index system for Jingle County in Shanxi Province. The quantitative assessment and zoning of ecological vulnerability in 2007 and 2017 was calculated with the aid of spatial principal component analysis method, remote sensing data and geographic information technology. The characteristics of the spatio-temporal evolution of ecological vulnerability were also revealed. The results show that:(1) Through the analysis of principal component characteristics, elevation deviate degree, soil erosion degree, per capita area of cultivated farmland, annual average precipitation, and GDP per capita indices were the main factors affecting the ecological vulnerability of the study area. (2) The ecological vulnerability types in Jingle County were mainly composed of four types:slight, light, moderate and severe vulnerability. In 2007, it was mainly characterized by light vulnerability and moderate vulnerability, and in 2017 it was mainly characterized by moderate vulnerability and severe vulnerability. Spatially, the central area was more vulnerable than the surrounding area showing a declining trend from center to both sides of the middle part of the study area. (3) The total area of mutual shift between various types of ecological vulnerability was 662.84 km² from 2007 to 2017. The mutual transfer was mainly happening for light and moderate vulnerability. The light vulnerability mainly shifted to moderate vulnerability and moderate vulnerability mainly shifted to severe vulnerability, with the transfer areas of 472.90 and 187.65 km², respectively. The basic trend of "light to moderate evolution, moderate to severe evolution" in space showed that the ecological situation was severe. (4) According to the characteristics of spatio-temporal evolution, the ecological restoration area, balance area and degradation area were divided. This study can provide scientific support and research ideas for the development of ecological restoration and governance in Jingle County and similar areas.

Tea plantation and expansion, a typical process of regional land use/cover change (LUCC), is closely related to agricultural development and sustainable land use. Taking the Shihe District of Xinyang City, the main producing area of high quality green tea in China, as an example, the spatio-temporal evolution in the distribution pattern of tea plantations from 1990 to 2015 was explored by coupling with multi-source data such as remote sensing images and land use data, etc. Random forest (RF) regression was used to explore driving mechanism of tea production expansion over two periods (1990-2000 and 2000-2015). Twenty-six exploratory variables, such as topography, land use, soil types, etc. were classified into biophysical and socioeconomic categories at the levels of pixel and village; and treated as the factors driving tea plantation expansion. The results show that tea plantations in the Shihe District are mainly distributed in hilly areas and shallow mountainous areas. From 1990 to 2000, the area of tea plantation expanded rapidly with a growth rate of 65.2%, while the expansion rate slowed down during 2000-2015. Tea plantations mainly expanded in the northwest and southeast directions, growing towards water sources and roads. The results indicate that driving factors of high importance can be divided into two scales:distance between tea garden and urban center/rural residential area at pixel scale, and soil types, slope and mean elevation at rural scale. Economic and technological development reduced restrictions imposed by biophysical driving factors such as land use and soil conditions. Spatial socio-economic conditions are increasingly essential for tea plantation expansion. The tea plantation expansion has a strong marginal dependence on the main driving determinants as growth tends to occur within 2 km from the rural settlements, where the average slope is 16-18° at village pixel region. Random forest regression is an efficient and effective means to explore the mechanisms of tea plantation expansion, which could provide guidance for sustainable land use planning.

It is of great significance to explore the spatial-temporal evolution laws of slope cultivated land utilization driven by various factors in karst trough valley area, which can help the regional food security and land management. Based on the high-resolution image and DEM as the data sources combined with field survey to verify the image, the slope cultivated land was calculated by using dynamic index and buffer analysis to study the general laws and differences of spatial-temporal evolution of slope cultivated land. The results are as follows:(1) During the period from 2005 to 2017, the slope cultivated land in the western, middle and eastern trough valley all changed dynamically and the most significant change were the gentle slope cultivated land and oblique slope cultivated land. (2) As the increase of distance between residential and road areas, the change of areas of slope cultivated land showed different decreasing trends. (3) In the western and eastern trough valley, the slope cultivated land transfer mainly focused on the trough basine, while in the middle trough valley mainly focused on the hillsides. (4) The spatial-temporal differentiation pattern of slope cultivated land evolution were affected by various factors, among them, the topography and landform of karst trough valley had a decisive role in the formation of slope cultivated land, the improvement of regional economic output had a transform effect on the slope cultivated land use and agricultural structure adjustment had diversity effect on slope cultivated land use function. Therefore to evaluate, the multi-factors and the evolution trend of slope cultivated land use in trough valley areas can provide scientific reference for regional local policy.

The structure of food consumption is changing gradually with the population growth, economic development and the improvement of residents' living standards. The environmental problems caused by food-source nitrogen consumption shall not be ignored. In present study, Changshu City, a typical county level city in the Yangtze river delta was taken as an example. The field survey and nitrogen-calculator model were applied to analyze the food nitrogen footprint and its influencing factors in the study area during 2000 to 2016. The results show that the per capita food nitrogen footprint of urban residents in Changshu from 2010 to 2016 was 14.68-20.00 kg·person^-1·year^-1 with the average value of (17.51±1.53) kg·person^-1·year^-1. While the value from the rural residents ranged between 17.58-24.87 kg·person^-1·year^-1, averaged at (20.49±2.55) kg·person^-1·year^-1. For the urban residents, the animal-derived food was dominant (≥ 66.42%) for the food nitrogen footprint. While the rural residents' food nitrogen footprint was mainly from the plant-derived food in 2000 (51.90%) and changed to be animal-derived food in 2016 (62.40%). In 2016, the nitrogen cost in food consumption in Changshu was 7.64 kg·kg^-1, 24.65% lower than that in 2000. The value was lower than the national level (9.90 kg·kg^-1) while higher than Beijing's level (2.50 kg·kg^-1). Food consumption structure, per capita GDP, per capita disposable income and urbanization rate are main factors affecting food nitrogen footprint in Changshu. The results could be beneficial for the urban sustainable development and the improvement of urban and rural ecological environment.

Climate change is likely to affect vegetation dynamics. The spatial-temporal interannual change in vegetation index were analyzed, and both seasonal variation and variation in growing season were assessed based on the satellite-derived normalized difference vegetation index (NDVI) and the daily climate data collected from 408 meterological stations all over northern China from 1982 to 2015. Further, the response of NDVI to climate change, particularly climatic extremes were studied, using GIMMS NDVI 3g V1.0, daily temperature and precipitation datasets. Across the whole of northern China, linear regressions indicated a increasing trend of growing season NDVI values at rate of 0.002 (10 a)^-1 from 1982 to 2015, as temperature increased and precipitation decreased. The extreme-point symmetric mode decomposition (ESMD) method showed that the increasing rates of NDVI gradually intensified until 1992, followed by a slightly declining until 2005, and then gradually increasing again. There were spatial differences in the NDVI changes and the area of vegetation improvement accounted for 62.8% of northern China. The regions with significantly increased NDVI were mainly distributed in the Tianshan Mountain and northern Tarim Basin in northern Xinjiang, Qilian Mountains and mountain area of Longnan in Gansu, the hilly region of western Liaoning, and the Loess Plateau, Hetao Plain, Lüliang Mountain, and Taihang Mountains in Shanxi Province. Regions with significantly decreased NDVI were predominantly distributed in the Daxing'an, Xiaoxing'an, and Changbai Mountains. The greatest increase in NDVI in northern China was observed in cultivated vegetation, grassland, and desert vegetation. The growing season NDVI in northern China was positively correlated with temperature and precipitation, and was more responsive to temperature. There was an obvious spatial heterogeneity in the distribution pattern. The extreme climate index was used to assess the response of NDVI to climate extremes. All extreme temperature indices showed highly significant increasing trend, whereas only maximum one-day precipitation (Rx1day) and very wet days (R95p) showed significant increase in extreme precipitation. Temperature extremes had stronger impact on NDVI than precipitation extremes, with minimum temperature (TMINmean) and warm nights (TN90p) most closely related to NDVI. The results suggest that climate change and climatic extremes potentially have deeper and more complex effects on ecosystems than previously understood.

The eastern part of Inner Mongolia is a high-risk area for drought disasters, it is necessary to use remote sensing to monitor drought conditions. In order to study the applicability of different remote sensing drought indices in eastern Inner Mongolia, MODIS data in the eastern part of Inner Mongolia from late April to late September 2016 were used to calculate four commonly used remote sensing drought indices:temperature condition index (TCI),vegetation condition index (VCI),temperature vegetation drought index (TVDI) and vegetation supply water index (VSWI), and compared with meteorological drought composite index (MCI) and soil relative humidity data. The results show that TCI and VCI had a large deviation in drought monitoring at the beginning of the growing season due to the different reviving periods. The drought indices were basically consistent with drought in the middle and late growth seasons. VCI and MCI had the highest correlation with soil relative humidity. The consistency of MCI with VCI and VSWI was higher in the middle and low coverage grassland, while the highest consistency with TCI was toward to the middle and high coverage grassland. Combined with the characteristics of various drought indices, VSWI is recommended for drought monitoring in eastern Inner Mongolia during the early growing season, and VCI or TCI is recommended for drought monitoring in the middle and late growth season.

The spatial distribution pattern of species diversity has always been one of the research hotspots in macroecology and biogeography. Northwest Yunnan is one of the regions with the richest biodiversity in China, and the researches on distribution pattern of species diversity and its correlation with main environmental factors have great significance for decision-making on biodiversity conservation. 18 counties in Northwest Yunnan were taken as basic research units, based on the county biodiversity background survey data, and ArcGIS 10.1 software was applied to analyze the diversity and distribution pattern of higher plants for each unit. Furthermore, linear regression analysis was performed to determine the relationship between species density and influencing factors including geographical factors[longitude(LONG), latitude(LAT), altitudinal variation(VALT), average altitude(ALT)] and climatic factors[mean annual temperature(MAT), mean annual precipitation(MAP)]. All statistical analyses were performed by using the SPSS Statistics 22.0 software. It has been found that:(1) The diversity of higher plants increases from south to north in Northwest Yunnan; (2) LAT and VALT have significant correlation on the distribution pattern of higher plants diversity; while the correlation with other factors, including LONG, ALT, MAT and MAP, is not significant with higher plants diversity in this region. As a result, it indicates that the distribution pattern of higher plant diversity in Northwest Yunnan may be mainly related to two major geographical factors:LAT and VALT.

The objective of the research is to explore the effects and mechanisms of biochars on CO₂ emission from Loess Plateau alkaline farmland soil. Maize straw-derived biochars (BCs) were prepared at 400, 600 and 800℃, and their carbon skeletons (BS) were extracted by hot water. After analyzing the fundamental physicochemical properties of the six kinds of materials, each was thoroughly mixed with the soil by the mass ratios of 1% or 2%, and subsequently an indoor static soil incubation experiment was carried out for 50 days. The results show that pH value and the amount of total alkaline oxygen-containing functional group of BC and BS significantly increased with the pyrolysis temperature increasing from 400 to 800℃, while the contents of dissolved organic carbon (DOC), readily oxidized organic carbon (ROC) and the amount of total acidic oxygen-containing functional group significantly decreased (P<0.05).[JP2]The contents of DOC and ROC in the BS were significantly (P<0.05) lower than that of BC produced at the same pyrolysis temperature. With the increase of the pyrolysis temperature of the added BC or BS, the cumulative CO₂ emissions of the treatments with BC or BS decreased. Moreover, the cumulative CO₂ emissions of the treatments with BC were higher than that with BS. Especially, the cumulative CO₂ emissions of BC-2% was significantly higher than that of BS-1% (P<0.05). During the whole incubation, the contents of DOC and ROC in the amended soil decreased. However, the reduction extent of DOC (87.90%-89.18%) was greater than ROC (19.29%-38.49%). Moreover, both the contents of DOC and ROC show the following trend:BC-2% > BC-1%/BS-2% > BS-1% > Control during the incubation of the soil amended with BC or BS prepared at 400, 600 or 800℃. Additionally, the results show that DOC content could explain the variance of CO₂ emissions more than ROC in the treatments with BC or BS amendment (P<0.01). DOC and ROC are the important factors affecting CO₂ emissions from Loess Plateau alkaline farmland soil. However, the impact of DOC on CO₂ emissions was more significant than ROC.

The adsorptions of Pb²⁺ and Cd²⁺ in aqueous solutions by biochar derived from salix, straw and corn stalk at pyrolysis temperature of 500℃ were evaluated. The characteristics of adsorbent were mainly observed by scanning electron microscope (SEM), specific surface area analyzer and Fourier transform infrared spectroscopy (FTIR), and the effects of initial pH, ionic strength of Na⁺ and Ca²⁺ and adsorbent dose in sorption experiments were further investigated. Results show that the alkali and ash content of the 3 biochars were salix straw biochar (SWB) > corn stover biochar (CB) > rice straw biochar (SB), and all the surfaces of the 3 biochars contained large number of oxygen-containing functional groups. The adsorption kinetics and adsorption results indicate that when the pH was set between 3 to 6, the adsorption efficiency of biochar to Pb²⁺ and Cd²⁺ increased with the increase of pH value, and the adsorption efficiency to Pb²⁺ decreased with the increase of ionic strength in the solution. While the adsorption efficiency of SWB on Cd²⁺ increases with increasing ionic strength. In addition, the adsorption kinetic results of SWB, CB and SB to Pb²⁺ and Cd²⁺ met quasi-secondary kinetics, and the correlation coefficient R² was greater than 0.99, indicating that the biochar adsorption rate is mainly determined by the chemical adsorption mechanism. Moreover, the adsorption isotherm model of Pb²⁺ and Cd²⁺ show that the adsorption of Cd²⁺ was suitable to be described by both Langmuir and Freundlich isothermal equation, while the adsorption of Pb²⁺ was only well simulated by the Langmuir isothermal equation, indicating that the adsorption mechanism of Pb²⁺ by biochar was similar to that of monolayer adsorption law, but the adsorption process of Cd²⁺ showed multi-molecular layer adsorption mechanism.

It is of significance to select most efficient passivators for remediation of Cd polluted soils. Four conventional passivating agents, namely calcium carbonate, calcium silicate, dihydrogen phosphate and sodium sulfide, were compared for their efficacy to immobilize Cd in soils. Pot experiments were carried out to investigate passivation effects of passivators on fractionation and bioavailability of Cd in a Cd-contaminated red soil. The results indicate that addition of calcium carbonate, calcium silicate or sodium sulfide increased soil pH, whereas a reversal trend was observed with dihydrogen phosphate. At the application rate over 0.5%, soil pH values increased to higher than 8.5 with addition of calcium silicate or sodium sulfide, decreased to below 6.0 with addition of dihydrogen phosphate and maintained stable at 7.6 with addition of calcium carbonate. According to changes of soil Cd forms, the passivation efficiency decreased in the following orders:calcium carbonate, dihydrogen phosphate, sodium sulfide, calcium silicate. The maximum Cd immobilization rate of 10.61% was achieved after application of calcium carbonate in soil. Besides, wheat growth and grain yield were obviously promoted by dihydrogen phosphate and calcium carbonate, but strongly inhibited by sodium sulfide, and barely affected by calcium silicate. Cd contents in grain decreased by 32%, 27% and 19% with the addition of dihydrogen phosphate, calcium carbonate, calcium silicate, respectively, all meet with the food safety standard. The pot experiment demonstrations that 0.5% calcium carbonate is more suitable to remediate Cd-contaminated red soil, because of its higher ability of increasing soil pH and lowering Cd mobility.

Lead (Pb) and cadmium (Cd) contaminated soil in a farmland in Shaoguan City, Guangdong Province was studied. A pot experiment was conducted to study the effects of single and multiple application of lime (w=0.2%) and humic acid (w=1%, 2% and 5%) to Pb and Cd contaminated soil on soil physical and chemical properties, available Pb and Cd content, Pb and Cd absorption and growth of ryegrass (Lolium perenne). Based on this, the regulation efficiency of lime and humic acid on Pb and Cd bioavailability in soil was discussed. Results show that the soil pH could be improved by the application of single lime or lime combined with humic acid treatment, while the concentrations of available Pb and Cd in soil was significant reduced. Especially, as compared with control, the content of available Pb and Cd decreased by 89.45% and 89.63%, respectively, when lime was mixed with 5% humic acid. There was a significant increase in the content of soil organic matter and the growth of ryegrass with application of single humic acid or lime combined with humic acid. There was a significant decrease in the absorption of Pb and Cd by ryegrass. The Pb absorption in the aboveground part of treatment with lime + 5% humic acid was significantly lower than those of other treatments, which was about 48.52% lower than that of the control. The Cd absorption in the aboveground part of treatment with single 5% humic acid was significantly lower than those of other treatments, which was about 59.62% lower than that of the control. Besides, the regulation efficiency of bioavailability of Pb and Cd in soil by the combined application of lime and humic acid was better than that of single humic acid or lime. There was a significant interaction between lime and humic acid.

Livestock manure applications may result in potential water pollution. Runoff experiments were established in South China to study the characteristics of runoff pollutant discharge in paddy fields caused by swine manure utilization. Four groups of fertilization management practices were considered in this study, including chemical fertilizer application (CK), fresh manure application (C3), organic manure application (C2) and biogas slurry application (C1). Results show that the concentration of total nitrogen, ammonia nitrogen and total phosphorus in the runoff peaked within the first 7 days after fertilization, then rapidly declined before reached stable on the 21st day. In C3, the TN loss reduced by 24.5% compared with CK. On the contrary, the NH₃-N loss increased by 33.3%, the TP loss increased by 25.8%, and the COD loss increased by 24.2%. Similarly, in C2 the TN loss reduced by 35.1%, and the COD loss increased by 8.8% compared with CK. There was no significant difference of TP loss and NH₃-N loss between CK and C2. In C1, the TN and TP loss reduced by 33.9% and 35.9% respectively, compared with CK. Nevertheless, there was no obvious change in NH₃-N loss, and the COD loss increased by 22.2%. In terms of potential water pollution, C1 and C2 appeared to be the more appropriate swine manure application methods, as they could not only reduce chemical fertilizer usage, but also decrease the risk of N and P pollution caused by surface runoff. Fresh manure application is not suggested in agriculture production.