China is in the critical period of ecological civilization construction. The ecological security is an essential foundation for ecological civilization construction and sustainable development promotion, which makes it the hot spot for both researchs and managements. Based on the latest research advances in the related fields of ecological security, the development of ecological security assessment model and the dynamics of ecological security management in China have been summarized. The application of the main assessment models (including the pressure-state-response model, ecological footprint model, landscape ecology model and ecosystem service model) are introduced. The development of researches on early-warning of ecological security is also discribed. In the aspect of ecological management measures, with the purpose of guaranteeing national ecological security, the guarantee policies of ecological security is systemically summarized, and the environmental management measures of ecological restoration, ecological conservation redline delineation and "green shield" natural reserve patrol are introduced. Based on the above mentioned contents, an outlook on the research and management of ecological security in the future is provided. It is recommended that the research should pay attention to the spatial match of the assessment units and the temporal dynamics of the assessment. In the meanwhile, the government should attach more importance to potential risk, emerging technology and comprehensive management oriented by ecological functions. The findings of this study could provide references for the study and management of ecological security in China.

Stormwater ponds, which are widely used in the practice of urban stormwater management, have become common features of the urban landscape. While, as open receiving water systems, stormwater ponds are exposed to strong anthropogenic pressures, and then prone to show as ecological fragility and vulnerability. Therefore, assessing the ecological risks of stormwater facilities is crucial for ensuring both the preservation and rehabilitation of biodiversity in urban areas. Although, the application of established integrated assessment methodologies, such as the sediment quality triad (SQT), is widely used around the world, the selection of reference sites and lacked adoption of integrated interdisciplinary approaches with consistency and specificity is challenged by the man-made features of urban stormwater ponds. The search for a more scientific and effective integrated assessment methodology to define and confirm the biological status of stormwater ponds ecosystem has great significance to understand the potential ecological risks of stormwater. Therefore, current research in the field of ecological risk assessments of urban stormwater ponds is reviewed at first, and limitation of current approaches based on benthos is analyzed on the aspect of reference sites. And on this basis, two definitions of ecological quality functional objectives, and the benefits and prospects of supplementing the SQT with the oligochaete index methodology (OIM) adapted to the conceptual framework of ecological quality goals are introduced. We suggest that future researches on ecological risk assessment of urban stormwater pond should focus on integrated interdisciplinary approaches with independence (or less dependence) on reference sites from the perspective of the definitions of ecological objectives, and the development of standardized protocols.

As a major agricultural province, Hebei provides an important guarantee of food security for Beijing-Tianjin-Hebei region. However, due to overexploitation of groundwater and excessive application of pesticide and chemical fertilizer, the agricultural production process in Hebei has caused a series of environmental problems, which in return restrain the system from sustainable development. Data of input resources were collected for Hebei Province's agricultural eco-economic system during 2001-2016. Emergy theory and ternary diagram were combined to analyze resource allocation and its tendency of system input and optimize development path of the system. The results showed that the allocation of system input resources gradually changed. Specifically, the renewable emergy utilization ratio for the system gradually decreased and the rate of non-renewable environmental resource utilization also decreased, while the ratio of purchased non-renewable emergy input gradually increased. The changes in resource allocation indicated that the system became less dependent on the local environment, but the dependence of system on the external emergy input was gradually enhanced. Moreover, the increasing of emergy investment rate suggested that agricultural production process should consume more purchased emergy while using the same amount of local resources. The ratio of renewable resources to non-renewable resources kept as 1.71:1 showed that the input of renewable resources was higher than that of non-renewable resources, indicating that Hebei Province has sound natural environment and climatic resources. However, the emergy sustainability index (ESI) values during the study period were lower than 1 with a yearly decrease, which means the system was not sustainable in the long run. According to system tendency analysis, comprehensive measures should be taken to keep stable the ratio of non-renewable resource emergy to purchased emergy and to increase the input of renewable resources in order to realize sustainable development of agricultural eco-economic system in Hebei Province.

To explore the carbon reduction effect and application driving factors of low-carbon planting technologies, the application status and carbon reduction contribution of low-carbon planting technologies were analyzed based on field survey data for 376 households in Fuzhou, Ganzhou, Jiujiang and other regions in Jiangxi Province in 2016 and 2018. Based on the low-carbon planting technologies application index, this paper analyzes the driving factors for the application of low-carbon planting technologies. It was found that the carbon reduction effect of low-carbon planting technologies depends on the proportion of emissions from each carbon source (chemical fertilizers, pesticides, agricultural diesel, and agricultural film) in the planting industry and its degree of application. The farmers' recognition of low-carbon planting technologies is low. The application level of low-carbon planting technologies increases with lower average age of head of household and spouse, more convenient transportation, hoping to sell agricultural products and learn agricultural policy through the internet, actively participating in training, and training involves low carbon planting technologies. According to the above research results, suggestions for promoting the application of low-carbon planting technologies are put forward.

Polychlorinated biphenyls (PCBs) in molluscs may pose a potential threat to consumer health, but research is currently limited. In order to explore the threat of PCBs to consumer health in marine molluscs, GC-MS was used to determine the content of 7 kinds of indicator PCBs in 6 kinds of molluscs sold in Haikou, the pollution level was evaluated and the carcinogenic risk to consumers was assessed. The results showed that the content of seven indicator PCBs in marine molluscs sold in Haikou was 17.51-47.43 ng·g^-1 (dry weight), and the average content was 32.78 ng·g^-1. The composition of indicator PCBs in molluscs was dominated by medium and low chlorinated PCBs (trichloro, tetrachloro and pentachloro-PCBs), of which tetrachloro-PCBs are the most important component of indicator PCBs in marine molluscs in Haikou. They accounts for 38.49% of the total PCBs. The total content of PCBs in marine molluscs sold in Haikou was much lower than the USA and China's limits, indicating that the pollution of PCBs in molluscs was at an acceptable level. Compared with other studies in China, the total content of PCBs in marine molluscs sold in Haikou was at a medium level. The 5%, 50%, and 95% carcinogenic risk of indicator PCBs in molluscs sold in Haikou through the molluscs intake for adult consumers were less than the threshold value of the US Environmental Protection Agency, indicating that the carcinogenic risk of indicator PCBs in marine molluscs sold in Haikou was at an acceptable level for adult consumers.

The contents and the speciation distribution of heavy metals (As, Hg, Cu, Pb, Zn, Cr, Ni and Cd) in surface sediments of Haiyan County, Zhejiang Province were analyzed for the study. The assessment of ecological risk was conducted by using geo-accumulation index (I_geo), potential ecological risk index (I_R), sediment quality guidelines (SQC), mERM-Q values and speciation distribution method. The results show that most of the surface sediment samples were contaminated by As、Cd、Cr、Cu、Ni、Pb and Zn in different degrees, and Zn was the most pervasive one.The geo-accumulation index indicated that heavy metal contamination in the most of aquatic sediment ranged from slight to severe, 16 and 10 sampling sites respectively showed over light pollution of Zn and Cd.The potential ecological risks of the studied single heavy metal were presented in the following decreasing order:Cd > Hg > As > Cu > Pb > Ni > Zn > Cr. Cd is the main ecological risk element in the study area. The ecology risks was moderate in HN6 (I_R=263), HN11 (I_R=193) and HN20 (I_R=269) sampling sites according to the potential ecological risk index. The SQC displayed different levels of heavy metal contamination in sediments at different sampling sites and different effects on aquatic organisms. The mERM-Q value also indicated different degrees of ecology risks. Since in the study area Cr mainly exists in the non-transferable state, while the other heavy metals are mainly extractable, urgent attention is needed in order to avoid the secondary pollution of heavy metals when environment condition changes.

Most of the nature reserves need to alleviate poverty in their regions while protecting their ecosystems. The spatial pattern of rural settlements in natural reserves is the result of multiple factors such as local natural environment, social economy and so on. The study on the spatial pattern of rural settlements in nature reserves can identify the spatial characteristics and differentiation rules of settlements, and provide decision-making support to regulate and guide future rural development in nature reserves, and to coordinate ecological protection and economic development. Taking Yaoluoping National Nature Reserve as an example, the study analyzes the scale, shape and distribution of rural settlements in Yaoluoping Nature Reserve using landscape pattern analysis and GIS, and explores the impact of topography, water resources, location and social factors on the pattern of rural settlements. The study has the following findings:(1)The spatial patterns of rural settlements in Yaoluoping Nature Reserve differ greatly from one functional area to another. To be specific, settlements in the core and buffer areas are clustered together and have smaller sizes and unregular shapes, whereas the settlements in the experimental area are clustered together and have larger sizes and regular shapes. (2)Terrain, water system, and road have a notable impact on the spatial pattern of the settlements in the reserve. For instance, most rural settlements are located less than 200 m away from rivers and roads at an elevation of no more than 800 m and a slope of less than 15°.(3)The spatial pattern of settlements is also closely related to social factors such as population distribution, economic development, and protection policies.

To explore the relationship between soil factors and plant functional groups (PFGs), research sample plots were set up under the degraded alpine meadow. Plant community characteristics and soil physic-chemical properties as well as their redundancy analysis (RDA) were determined. The results showed that with the aggravation of degradation, the important values of cyperaceae and gramineae PFGs tended to decrease, while forbs PFGs increase; PFGs succession was from cyperaceae and gramineae to leguminosae and forbs; Further, soil organic carbon and nitrogen tended to decrease, while soil temperature and bulk density tended to increase. From RDA, the first and second axises explained the 97.1% of PFGs variation and the relationship of 99.6% between PFGs and soil factors. Soil water content and total nitrogen showed positive correlation with the first axis, while soil bulk density and soil temperature showed negative correlation with the first axis, which indicate that various soil factors have different marginal effects. Soil water and total nitrogen contents had significant effects on the distribution of PFGs (P<0.01). The correlation coefficients between cyperaceae important value and soil total nitrogen as well as soil water content were 0.960 and 0.959, respectively (P<0.01). The correlation coefficients between gramineae important value and soil water content as well as organic carbon were 0.937 and 0.929, respectively (P<0.01). Soil bulk density and water content had important effects in leguminosae and forbs PFGs. In conclusion, there existed correlation between PFGs and soil factors in degraded alpine meadows, and various soil factors showed different effects on PFGs, which were more sensitive to the changes of soil total nitrogen and soil water content.

The addition of urease/nitrification inhibitors is an important measure to reduce greenhouse gas emissions in paddy fields. The interaction effects of biochemical inhibitor combinations[N-(n-butyl)thiophosphoric triamide (NBPT), N-(n-propyl)thiophosphoric triamide (NPPT) and 2-chloro-6-(trichloromethyl)pyridine (CP)] and fertilization models (one-off and three-time fertilizations) on greenhouse gases (CH₄ and N₂O) emission flux were investigated from yellow clayey field during rice (Oryza sativa) growth season using two factors randomized block design, and calculated global warming potentials (GWPs) and greenhouse gas intensity (GHGI). The results show that CH₄ and N₂O emission flux had obvious seasonal variation under different fertilization treatments. The three-time urea fertilization treatment significantly reduced CH₄ and N₂O emissions, GWPs and GHGI during rice growth season than those of one-off urea fertilization treatment by 13.5%, 20.7%, 14.4% and 25.0%, respectively. Nitrification inhibitor CP treatment significantly reduced the peak of N₂O emission flux, as well as CH₄ and N₂O emissions during rice growth season under different fertilization models. On the other hand, urease inhibitor NBPT/NPPT combined with CP treatment could more effectively reduce CH₄ and N₂O emissions, as well as GWPs and GHGI during rice growth season. Application of a new urease inhibitor NPPT alone or combined with CP had the similar greenhouse gas emission laws with NBPT during rice growth season. In conclusion, combined biochemical inhibitors and appropriate managements can guarantee the production of rice and effectively reduce greenhouse gas emissions from paddy field, therefore, it is a feasible fertilization practice for low carbon emission and higher yield of rice.

In order to investigate the influence of effluents from the sewage treatment plants to the receiving waters, XAD-8, anion-exchange and cation-exchange resins were used to separate and enrich the effluents from different sewage treatment plants and the samples from the upstream and downstream of the Zhu Zhuan Jing sewage treatment plant's outlet, and six components were acquired such as the hydrophilic base (HIB), hydrophilic acid (HIA), hydrophilic neutral substance (HIN), hydrophobic base (HOB), hydrophobic acid (HOA) and hydrophobic neutral substance (HON). Mathematical methods such as DOMFluor, PARAFAC and PAC projection approach were used to decompose the EEM fluorescene spectra of the former five components and those of the original effluents, and three principal components, i.e. the protein-like, fulvic-like and humic-like substances, were acquired. According to the analysis result of Fourier Tranform Infrared (FTIR) spectroscopy, hydrophilic substances were mainly composed by polysaccharides, proteins, phosphate, etc. On the other hand, hydrophobic substances were mainly composed by lipids, organic acids and so on. In addition, the principal components scores were compared which were decomposed from the EEM fluorescence spectra of the upstream and downstream samples from the Er Shi Bu river. Results show that the receiving waters was seriously polluted and the effluents from sewage treatment plants had little effect on the receiving waterbody.

Phragmites australis has a strong capacity of the absorption to heavy metal cadmium, which can effectively reduce the cadmium content of its growing environment. After being abstracted by reed, the cadmium is converted into different forms. The cadmium extracted by sodium chloride (SCd) is the main form in reed. In order to study the effects of different concentrations of cadmium on the SCd and the activity of gamma-glutamylcysteine synthetase (γ-GCS) in reed, the cadmium chloride solutions of 5 levels (0.5, 1.0, 2.0, 3.0 and 5.0 mmol·L^-1) were used to irrigate the Phragmites australis at different growth stages, and the accumulation of cadmium (SCd) and the change activity of γ-GCS in reed were measured. The results show that:(1) When the concentration of cadmium chloride solution increased, the accumulation amount of SCd in the roots, stems, and leaves of reed first increased and then decreased;(2) The accumulation amount of SCd in different parts of the reed was different at different stages. During the mature stage, the accumulation amount of SCd reached the maximum. It was 3 984.16 mg·kg^-1 in root, which was 7.33 times as that in the stems, and 4.83 times as that in leaves; (3) When the concentration of cadmium chloride solution was less than 3.0 mmol·L^-1, the activity of γ-GCS in roots, stems and leaves of reeds increased with the increase of concentration of cadmium chloride solution. When the concentration of cadmium chloride solution was greater than 3.0 mmol·L^-1, the activity of γ-GCS was suppressed.

Spinach (Spinacia oleracea) was planted in contaminated soil with different level of polycyclic aromatic hydrocarbons (PAHs) through pot experiment. The content and composition of 16 PAHs in soils and spinach were detected, the transfer factors of PAHs in each part of spinach were analyzed, and the health risks of PAHs in spinach for people with different age were assessed. The results show that the content of PAHs in aboveground and underground part of spinach was 72.8-516.9 and 153.4-1 101.6 ng·g^-1, respectively. There was a significant positive correlation between the content of PAHs in soil and that in spinach. The mass fractions of 3 rings and 4 rings PAHs in each part of spinach were high, and the mass fractions of carcinogenic compounds in the aboveground part of spinach was in the range of 5.4%-30.6%. The transfer factor of PAHs in underground part of spinach was higher than that in the aboveground (P<0.05). Children, adults and the elderly have a lifetime cancer risk if they ingest spinach grown in diesel contaminated soil, and adults and the elderly have a lifetime cancer risk if they ingest spinach grown in heavily contaminated soil. In addition to adults, other people do not have lifetime cancer risk through ingestion of spinach grown in mildly and moderately PAHs contaminated soil. The lifetime cancer risk is higher in spinach grown in diesel contaminated soil than in other soils.