Dynamic changes of wetland resources based on MODIS and Landsat image data fusion

Abstract Given the seasonal dynamics of wetland ecosystem, limited available data, and technological method of wetland investigation, wetland evaluation cannot be accurately accessed. Although the remote sensing technology has been widely employed on wetland investigation and identification, changeable weather conditions especially cloud interference are the main barrier to acquire clear remote sensing image for wetland identification and information extraction. The combination and precision evaluation of remote sensing data with high temporal-spatial resolution ratio from moderate-resolution imaging spectroradiometer (MODIS) and Landsat were conducted using the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM): a comprehensively temporal-spatial reflectance model was built; the high-resolution image in the time series and Modified Normalized Difference Water Index were obtained. The main data obstacles in wetland resources monitoring were invalid. The typical wetland areas in Liaoning province of China were evaluated using combination algorithm and Landsat (Thematic Mapper) images. The results show that the MODIS and Landsat data can be combined well with high correlations in different wave ranges. The maximum Normalized Difference Water Index (NDWI) is 0.9678, followed by green wave (0.9630), near-infrared wave (0.9345), and blue wave (0.9018).The wetland seasonal change of Panjin was examined using the data combination method. Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), and vegetation coverage index were extracted from combined images of Panjin from June 2016 to August 2016 and analyzed. Results showed that the NDVI was high in partial water area during the studied period indicating high chlorophyll contents

A Quantitative Survey of Effect of Semi-Natural Habitat Composition and Configuration on Landscape Heterogeneity in Arable Land System

Arable land systems are complex ecosystems composed of cultivated land and semi-nat-ural habitats. Retaining an appropriate proportion of semi-natural habitats in arable land systems is beneficial for enhancing landscape heterogeneity and biodiversity. However, it is unclear how many semi-natural habitats need to be retained in arable land systems to improve landscape heter-ogeneity. In this study, the land use data of four counties were used as the data source in the Lower Liaohe Plain, Liaoning Province, and Rao’s quadratic entropy index (Q) was used to quantitatively characterize the landscape heterogeneity. We aimed to explore the minimum proportion of semi-natural habitat required to maintain high landscape heterogeneity and determine the independent and interactive effects of semi-natural habitat composition and configuration on landscape hetero-geneity. We found that (1) maintaining a 5% proportion of semi-natural habitats is the minimum threshold for achieving high landscape heterogeneity in arable land systems. Retaining a 10% share of semi-natural habitats is beneficial for both agricultural production and land ecology. (2) The com-bination of woodland, water and ditches was good for improving landscape heterogeneity. Connectivity in semi-natural habitats is critical to improving landscape heterogeneity. (3) The interac-tion of semi-natural habitat composition and configuration had a strong effect on landscape heterogeneity (53.1%). Semi-natural habitat configuration was found to be more important than composition for landscape heterogeneity. The role of semi-natural habitat composition and configuration in maintaining landscape heterogeneity and supporting the sustainability of land use therefore needs to be considered in arable land systems

Spatial-Temporal Changes of Soil Organic Carbon Content in Wafangdian, China

Soil organic carbon (SOC) plays an important role in soil fertility and the global carbon cycle. A better understanding of spatial-temporal changes of SOC content is essential for soil resource management, emission studies, and carbon accounting. In this study, we used a boosted regression trees (BRT) model to map distributions of SOC content in the topsoil (0–20 cm) and evaluated its temporal dynamics from 1990–2010 in Wafangdian City, northeast of China. A set of 110 (1990) and 127 (2010) soil samples were collected and nine environment variables (including topography and vegetation) were used. A 10-fold cross-validation was used to evaluate model performance as well as predictive uncertainty. Accuracy assessments showed that R2 of 0.53 and RMSE (Root-mean-square error) of 9.7 g∙kg−1 for 1990, and 0.55, and 5.2 g∙kg−1 for 2010. Elevation and NDVI (Normalized Difference Vegetation Index) were the two important variables affecting SOC distribution. Results showed that mean SOC content decreased from 19 ± 14 to 18 ± 8 g∙kg−1 over a 20 year period. The maps of SOC represented a decreasing trend from south to north across the study area in both periods. Rapid urbanization and land-use changes were accountable for declining SOC levels. We believe predicted maps of SOC can help local land managers and government agencies to evaluate soil quality and assess carbon sequestration potential and carbon credits

Dominant Aggregate Binding Agent Dynamics of Quaternary Ancient Red Soils under Different Land Use Patterns

The cementation mechanisms and processes of aggregate binding agents are important in understanding aggregate formation. However, the role of threshold values and the proportions of organic and inorganic binding agents in aggregate formation remain unclear. This research investigated the dominant aggregate binding agent dynamics in a sequence comprising buried ancient red soil unaffected by modern climate changes and human activities, alongside nearby exposed Quaternary ancient red soils subjected to different land use patterns influenced by these factors in northeastern China. By analyzing soil age, aggregate compositions, and organic/inorganic indicators of binding agents, including soil organic matter (SOM), free iron oxide (Fed), poorly crystalline iron oxide (Feo), crystalline iron oxide (Fed-Feo), and total clay particles (TCL), we determined the relative contributions of different binding agents using redundancy analysis (RDA). The results revealed that the buried ancient red soil did not contain dominant binding agents in the aggregate formation before 91.01 ka BP. Due to denudation, the buried ancient red soil was exposed at the surface and experienced the importation of soil organic matter, weathering of silicate-bound iron oxides, and crystallization of poorly crystalline iron oxides resulting from the effects of different land use patterns from 91.01 ka to the present. Under the influence of binding agent dynamics, dominant binding agents in the exposed Quaternary ancient red soils’ aggregate formation changed into SOM and Fed. When the C/(Fed-Feo) molar ratio was less than 2.13, Fed-Feo was the dominant aggregate binding agent. When the C/(Fed-Feo) molar ratio was greater than 2.13, SOM was the dominant aggregate binding agent. The results of this study improve our understanding of aggregate formation and the relationship between soil organic matter and iron oxides

An improved similarity-based approach to predicting and mapping soil organic carbon and soil total nitrogen in a coastal region of northeastern China

Soil organic carbon (SOC) and soil total nitrogen (STN) are major soil indicators for soil quality and fertility. Accurate mapping SOC and STN in soils would help both managed and natural soils and ecosystem management. This study developed an improved similarity-based approach (ISA) to predicting and mapping topsoil (0–20 cm soil depth) SOC and STN in a coastal region of northeastern China. Six environmental variables including elevation, slope gradient, topographic wetness index, the mean annual temperature, the mean annual temperature, and normalized difference vegetation index were used as predictors. Soil survey data in 2012 was designed based on the clustering of the study area into six climatic vegetation landscape units. In each landscape unit, 20–25 sampling points were determined at different landform positions considering local climate, soil type, elevation and other environmental factors, and finally 126 sampling points were obtained. Soil sampling from the depth of 0–20 cm were used for model prediction and validation. The ISA model performance was compared with the geographically weighted regression (GWR), regression kriging (RK), boosted regression trees (BRT) considering mean absolute prediction error (MAE), root mean square error (RMSE), coefficient of determination (R2), and maximum relative difference (RD) indices. We found that the ISA method performed best with the highest R2 and lowest MAE, RMSE compared to GWR, RK, and BRT methods. The ISA method could explain 76% and 83% of the total SOC and STN variability, respectively, 12–40% higher than other models in the study area. Elevation had the largest influence on SOC and STN distribution. We conclude that the developed ISA model is robust and effective in mapping SOC and STN, particularly in the areas with complex vegetation-landscape when limited samples are available. The method needs to be tested for other regions in our future research

Effect of carbon fiber tow structure on ablative properties of carbon fiber/phenolic composites

Carbon fiber reinforced carbon/phenolic composites were prepared by using phenolic resin as matrix, plain carbon cloth and short carbon fiber as reinforcing agent. The ablation resistance of the composite was studied by oxygen/acetylene ablation test. The bending property of the composite was characterized by electronic tensile testing machine. The ablation surface of the composite was observed by scanning electron microscope. The ablation performance of the composite was verified by solid rocket motor. The results show that the mass ablation rate of oxyacetylene in carbon/phenolic composites prepared with these two structural forms of carbon fibers as reinforcements has a positive correlation with the size of carbon fiber tow. The smaller the carbon fiber tow, the lower the mass ablation rate of carbon fiber. When the carbon fiber reinforcer is in the single filament state, the oxyacetylene mass ablation rate of the composite is the lowest, which is 0.046 g/s, and the influence of carbon fiber type and specification on the mass ablation rate of oxyacetylene becomes smaller. The experimental results of solid rocket motor show that the ablation erosion resistance of carbon fiber/phenolic composites in monofilament state is obviously better than that of bundle carbon fiber/phenolic composites

Silencing of Intestinal Glycoprotein CD98 by Orally Targeted Nanoparticles Enhances Chemosensitization of Colon Cancer

Colon cancer is among the most widely occurring cancer types, leading to considerably high mortality rate. The current chemotherapy achieves only limited success, and more effective therapeutic strategies are urgently needed. Human colonic biopsy specimens indicate increased expression of CD98 in patients with colon cancer, suggesting that CD98 might be a potential therapeutic target and/or a receptor for targeted drug delivery in colon cancer treatment. Herein, we coloaded CD98 siRNA (siCD98) and camptothecin (CPT) into CD98 Fab′-functionalized nanoparticles (NPs). The resultant Fab′-siCD98/CPT-NPs showed good monodispersity with an average diameter of approximately 270 nm and a ζ-potential of around −24 mV. These NPs mediated efficient drug delivery to the target cancer cells and tumor tissues, producing much better anticancer and antimigration effects compared to other relevant NPs. Mouse models with orthotopic colon tumors were treated with NP-embedded hydrogel, which revealed that Fab′-siCD98/CPT-NPs exhibited a therapeutic efficacy significantly better than that of single drug-loaded NPs or nonfunctionalized siCD98/CPT-NPs. This study indicates that the Fab′-siCD98/CPT-NP/hydrogel system is able to realize specific release of NPs in the colonic lumen and enable drugs (siCD98 and CPT) to be internalized into target cells, demonstrating a notable potential for clinical applications in colon-cancer-targeted combination therapy