Ecological transformation is the key to improve ecosystem health for resource-exhausted cities: A case study in China based on future development scenarios.

Numerous cities are currently grappling with the challenge of ecological transformation, especially those categorized as resource-exhausted cities. In these urban areas, land use change is a highly scrutinized issue, as different land use strategies can lead to varied outcomes, impacting the ecological environment in multiple dimensions. Assessing ecosystem health reflects the quality of the regional ecological environment and serves as a comprehensive indicator for evaluating the sustainability and stability of urban ecosystems. To this end, a multi-objective optimization model was constructed to predict land use changes under four future development scenarios (four ecological transformation modes), using Shizuishan City (China), a resource-exhausted city situated in an ecologically fragile area, as an example. The "vigor-organization-resilience" assessment framework was employed to evaluate the ecosystem health conditions in each scenario from three dimensions. The study results showed: (1) The ranking of the average ecological health levels in Shizuishan City for 2022 and different future development scenarios is as follows: Low-Carbon Economic Development Scenario (0.302) > Ecological-Economic Coordinated Development Scenario (0.291) > Baseline Scenario (0.290) > Economic Development Scenario (0.281) > 2022 (0.248). (2) Compared to 2022, the ecosystem health levels under the four ecological transformation modes had all improved, with improvement areas accounting for over 60 %, highlighting the urgent necessity of ecological transformation in Shizuishan City. Among them, the Low-Carbon Economic Development Scenario exhibited the largest improvement area, reaching 75.81 %. (3) Ecological system vitality was identified as the dominant dimension influencing the ecological health in this region. This study emphasized multi-objective development needs and provided an integrated ecosystem health assessment method for assessing the comprehensive ecological effects of future ecological transformation modes in resource-exhausted cities.

Research on the sustainability of "greening" process in the Mu Us Sandy Land based on the spatiotemporal stability of ecological land.

In environmentally sensitive areas, especially the arid and semi-arid regions, the greening stability process and its influencing factors can directly affect the sustainable development of the ecological environment. In this study, multi-source remote sensing data such as land use/cover data, MODIS NDVI, and soil moisture, methods such as stability index, vegetation quantitative remote sensing, and Geodetector were employed to analyze the sustainability of the greening process in the Mu Us Sandy in 2000-2020, which were viewed from three aspects: changes in stability of land use types and function, soil moisture change and influencing factors on greening stability. The results showed that, (1) From the stability of land use types, continuous stable ecological land accounted for more than 50%, showing that decreased from northwest toward southeast. (2) From the functional stability, NDVI showed a fluctuated growth (0.035/a), with an increasing distribution pattern from northwest to southeast. Additionally, Vegetation changes were unstable and concentrated in the western part of the study area (OtogBanner and Otog Front Banner), while the eastern part was stable, in which vegetation improvement took the main position. Moreover, mobile dunes almost disappeared, and semi-fixed dunes decreased and gradually shrank to the west of the sandy area, while fixed dunes soared and were concentrated in the middle of the sandy land. (3) From the soil moisture change, soil moisture at different underground depths showed an overall increasing trend, but the deep soil moisture was higher than the shallow, and spatial distribution varied greatly. (4) From the influencing factors, natural factors significantly influence greening stability, among which precipitation had a particularly profound impact, and interactions with other natural and social factors were higher explanatory. The paper aims to explore whether the ecological environment is developing in a good and orderly direction in the Mu Us Sandy Land, and the potential factors that cause its changes, to provide a theoretical basis for scientific governance in the Mu Us Sandy Land and other arid and semi-arid areas in the future.

Effects of multi-scale structure of blue-green space on urban forest carbon density: Beijing, China case study.

Landscape structure influences the amount of carbon that can be stored in an ecosystem. Currently, majority of research have been focused on the responses of landscape structure and functional relationships to urbanization, and few have specifically focused on blue-green space. In this study, Beijing was used as a case study to explore the relationship among the blue-green spatial planning structure of green belts, green wedges and green ways, the landscape configuration of blue-green element and carbon storage of urban forest. The blue-green elements were classified using high-resolution remote sensing images (0.8 m) and the above-ground carbon storage estimations of urban forest based on 1307 field survey samples. The results show that green belts and green wedges have a higher coverage percentage of blue-green space and big blue-green patches than that of built-up areas. However, they have lower carbon density in urban forests. The shannon's diversity index of blue-green space was found to have a binary relationship with carbon density, in which, urban forests and water bodies were the key combination in increasing carbon density. The presence of water bodies in urban forests increases the carbon density to up to 1000 m. The effect of farmland and grassland on carbon density was found to be uncertain. With this, this study provides basis for sustainable planning and management of blue-green spaces.

Chitin/egg shell membrane@Fe3O4 nanocomposite hydrogel for efficient removal of Pb2+ from aqueous solution.

The development of adsorbents by using the byproducts or waste from large-scale industrial and agricultural production is of great significance, and is considered to be an economic and efficient strategy to remove the heavy metals from polluted water. In this work, a novel chitin/EM@Fe3O4 nanocomposite hydrogel was obtained from a NaOH/urea aqueous system, where the proteins of egg shell membrane and Fe3O4 nanoparticles were chemically bonded to chitin polymer chains with the help of epichlorohydrin. Due to the existence of a large number of -NH2, -OH, -CONH-, -COOH and hemiacetal groups, the adsorption efficiency for Pb2+ into the absorbent was dramatically enhanced. The experimental results revealed that the adsorption behavior strongly depends on various factors, such as initial pH, initial Pb2+ concentration, incubation temperature and contact time. The kinetic experiments indicated that the adsorption process for Pb2+ in water solution agreed with the pseudo-second-order kinetic equation. The film diffusion or chemical reaction is the rate limiting process in the initial adsorption stage, and the adsorption of Pb2+ into the nanocomposite hydrogel can well fit the Langmuir isotherm. Thermodynamic analysis demonstrated that such adsorption behaviors were dominated by an endothermic (ΔH° > 0) and spontaneous (ΔG° < 0) process.

Effects of tree canopy on psychological distress: A repeated cross-sectional study before and during the COVID-19 epidemic.

BACKGROUND: During the COVID-19 epidemic period, people showed a stronger connection to the environment within their communities. Although tree canopy in residential areas has been shown to positively affect psychological distress, it is not clear whether the COVID-19 epidemic played a role in this process. Elucidation of the relationship between tree canopy and the impact on psychological distress during the COVID-19 epidemic could provide valuable information as to the best methods to help individuals cope with urban mental stress events. METHODS: A total of 15 randomly selected residential areas of Beijing were enrolled in this repeated cross-sectional study. A total of 900 residents were included in the two-waves of the investigation (450 residents per wave) before and during the COVID-19 epidemic (i.e., May 2019 and May 2020). Psychological distress was estimated using the 12-question General Health Questionnaire (GHQ-12). Tree canopy coverage (TCC) was measured through visual interpretation based on the 2013 data sources (World View 2 satellite imagery of Beijing urban areas with a resolution of 0.5 m). The demographic characteristics, distance to the nearest surrounding green or blue space, residential area house price, household density, and construction year were also collected in this study. A multivariate logistic regression, relative risk due to interaction (RERI), and synergy index (SI) were used to explore the relationships among tree canopy, COVID-19, and psychological distress. RESULTS: The negative impact of the COVID-19 epidemic on mental health was significant, with the prevalence of psychological distress increased 7.84 times (aOR = 7.84, 95% CI = 4.67-13.95) during the COVID-19 epidemic period. Tree canopy coverage in the group without psychological distress was significantly higher than that of the psychologically distressed group (31.07 ± 11.38% vs. 27.87 ± 12.97%, P = 0.005). An increase in 1% of TCC, was related to a 5% decrease in the prevalence of psychological distress (aOR = 0.95, 95% CI = 0.93-0.98). An antagonism joint action between tree canopy and the COVID-19 epidemic existed (RERI = 1.09, 95% CI = 0.72-1.47; SI = 0.16, 95% CI = 0.05-0.52), and persisted enhancing only in medium (26.45%-33.21%) and above TCC level. Correlation of GHQ items and TCC significantly differed between the COVID-19 non-epidemic and epidemic periods, with the effects of tree canopy on GHQ-12 items covering topics, such as social function and depression, presumably absent because of epidemic limitations. CONCLUSIONS: This study indicates that the COVID-19 epidemic harmed mental health and verified the positive effects of residential tree canopy on psychological distress in Beijing. We suggest paying more attention to residents in areas of low TCC and dealing with psychological distress caused by public health stress events based on tree canopy strategies.

Fabrication of Hollow Materials by Fast Pyrolysis of Cellulose Composite Fibers with Heterogeneous Structures.

A facile method for the fabrication of inorganic hollow materials from cuprammonium cellulose composite filaments based on fast pyrolysis has been developed. Unlike Ostwald ripening, approaches based on the Kirkendall effect, and other template methods, this process yielded hollow materials within 100 s. The heterogeneous structure of the cellulose composite fibers and the gradient distribution of the metal oxides are the main reasons for the formation of the hollow structure. The diameter, wall thickness, and length of the hollow microfibers could be conveniently controlled. With their perfect morphology, these hollow structural materials have great potential for use in various fields.

Preparation of copper nanoparticles coated cellulose films with antibacterial properties through one-step reduction.

Regenerated cellulose (RC) films coated with copper (Cu) nanoparticles were prepared from cellulose-cuprammonium solution through coagulation in aq. NaOH and subsequent reduction in aq. NaBH4. Structure and morphology of the nanocomposite films were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results established the migration of Cu(2+) from the inner to the surface of the RC films during the coagulation of cellulose-cuprammonium solution and the reduction from Cu(2+) to Cu(0). Cu nanoparticles were found to be firmly embedded on the surface of the RC films. The RC films coated with Cu nanoparticles showed efficient antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The dramatic reduction of viable bacteria could be observed within 0.5 h of exposure, and all of the bacteria were killed within 1 h.

Electrospun nano-fiber mats containing cationic cellulose derivatives and poly (vinyl alcohol) with antibacterial activity.

Nano-fibrous mats have been successfully prepared by electrospinning of the blend solutions of cationic cellulose derivatives (PQ-4) and polyvinyl alcohol (PVA). Effects of the blending ratio and applied voltage on the morphology and diameter of the electrospun nano-fibers were investigated. The average diameter of the PQ-4/PVA blend fibers was in the range of 150-250 nm. The electrospinning process became instable and the fiber diameter distribution broadened with increasing PQ-4 content and applied voltage. The antibacterial activity of electrospun PQ-4/PVA blend mats against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus indicated potential for biomedical use.

[Preliminary research on environmental characteristics of oasis-desert ecotone].

Taking Minqin Oasis in the downstream of Shiyanghe Rivers as example, the shrub characteristics of sand dune, which was closely related to the vegetation of the interface between the outside of oasis and desert, was studied in this paper. The change of vegetation coverage and dune density indicated that the vegetation coverage in the ecotone was obviously higher than that in the outside of oasis and in drift desert. There existed an area outside oasis that was obviously affected by human activies and 0-600 m away from the outside of oasis. Meanwhile, the appearing position of area outside oasis was different in different place. The naked area ratio of dune in the area outside oasis was the biggest, so that the area outside oasis was the main resource of drift sand resulting in desertification of oasis. Over extracting ground water in oasis district resulted in a forming of dropping funnel of ground water there, and resulted in a fluid of ground water from desert to oasis. Ultimately, human activites aggravated those processes to some extent.