Spatial response of urban land use intensity to ecological networks: a case study of Xi'an Metropolitan Region, China.

In the face of the persistent degradation of ecological environments and fragmentation of ecological networks brought about by rapid urbanization, this study focuses on examining the interaction between urban land use intensity and ecological networks in the Xi'an Metropolitan Region (XAMR), China, and their impact on ecological equilibrium and sustainable development. By comprehensively evaluating the changes in land use intensity in XAMR from 2010 to 2020, the aim is to underscore the pivotal role of ecological networks in maintaining urban ecological balance and promoting sustainable development. The findings indicate a transition in land use intensity in the XAMR from low to high concentration, reflecting an intensification in land resource utilization during urbanization. However, the establishment and management of ecological networks can significantly enhance urban ecological security and biodiversity. Notably, this research identified crucial ecological corridors and source areas, augmenting the connectivity of urban green infrastructure and providing vital support for urban biodiversity. Additionally, a significant finding of this study is the spatial spillover effects generated by socioeconomic factors such as the proportion of tertiary and secondary industries and per capita GDP through the ecological network, which have profound impacts on land use intensity in the surrounding areas. These insights offer a novel understanding of the complex interactions within urban ecosystems, emphasizing the importance of incorporating ecological network construction in urban planning. Overall, through a comprehensive analysis of the relationship between the ecological network and land use intensity in the XAMR, this study proposes new directions for urban ecosystem management and land use planning, highlighting the significance of scientific ecological network planning and management in achieving long-term sustainable development in urbanization processes.

Biochar reduces antibiotic transport by altering soil hydrology and enhancing antibiotic sorption.

The performance of biochar (BC) in reducing the transport of antibiotics under field conditions has not been sufficiently explored. In repacked sloping boxes of a calcareous soil, the effects of different BC treatments on the discharge of three relatively weakly sorbing antibiotics (sulfadiazine, sulfamethazine, and florfenicol) via runoff and drainage were monitored for three natural rain events. Surface application of 1 % BC (1 %BC-SA) led to the most effective reduction in runoff discharge of the two sulfonamide antibiotics, which can be partly ascribed to the enhanced water infiltration. The construction of 5 % BC amended permeable reactive wall (5 %BC-PRW) at the lower end of soil box was more effective than the 1 %BC-SA treatment in reducing the leaching of the most weakly sorbing antibiotic (florfenicol), which can be mainly ascribed to the much higher plant available and drainable water contents in the 5 %BC-PRW soil than in the unamended soil. The results of this study highlight the importance of BC's ability to regulate flow pattern by modifying soil hydraulic properties, which can make a significant contribution to the achieved reduction in the transport of antibiotics offsite or to groundwater.

Association of serum asprosin with metabolic dysfunction-associated fatty liver disease in older adult type 2 diabetic patients: a cross-sectional study.

BACKGROUND: To explore the association of serum asprosin levels with metabolic dysfunction-associated fatty liver disease (MAFLD) in older adults with type 2 diabetes mellitus (T2DM). METHODS: The cross-sectional study enrolled patients ≥ 65 years old diagnosed with T2DM at two community health service centers between November 2019 and July 2021. Logistic regression was applied to analyze the influencing factors of MAFLD. RESULTS: Totally 219 cases were included. Compared with diabetic individuals without MAFLD (n = 105), diabetics with MAFLD (n = 114) had younger ages, higher body mass index values, shorter time from T2DM diagnosis, increased waist-to-hip ratios, elevated triglycerides, reduced high-density lipoprotein cholesterol (HDL-C), elevated alanine aminotransferase (ALT), elevated γ-glutaryl transferase, elevated fasting insulin, and elevated HOMA-IR (all P < 0.05). Serum asprosin levels were elevated in diabetics with MAFLD in comparison with the non-MAFLD group (291.71 ± 73.69 vs. 255.24 ± 82.52 pg/ml, P = 0.001). Multivariable analysis revealed, after adjusted for age, time from T2DM diagnosis, HDL-C, and ALT, serum asprosin level (OR = 1.006, 95%CI: 1.001-1.010, P = 0.014) were independently associated with MAFLD in T2DM. CONCLUSIONS: High asprosin level are associated with MAFLD in older patients with T2DM, after adjusted for age, time from T2DM diagnosis, WHR, TG, HDL-C, ALT, GGT, FINS, and HOMA-IR.

A novel tool for tracing water sources of streamflow in a mixed land-use catchment.

Tracing water sources of streamflow in a mixed land-use catchment is critical for predicting pollutant emissions from various human activities to streams but remains a major challenge. A rain event based field monitoring study was conducted in the Jieliu catchment located in the hilly area of central Sichuan Province, southwest China. The ratio of the maximum fluorescence intensities (Fmax) of the two humic-like dissolved organic matter (DOM) components at excitation/emission wavelengths of 255 (315)/415 nm (component 1; C1) and 260 (375)/480 nm (component 2; C2) was proposed as a tracer for quantifying streamflow water sources. Satisfactory performance of using the Fmax(C1)/Fmax(C2) ratio in hydrograph separation of streamflow at the outlet of a forest sub-catchment was verified by through comparison with the hydrograph separation results based on δ18O data. The Fmax(C1)/Fmax(C2) ratio was then applied to estimate the contributions of rainwater and pre-event water sources under different land use types to the streamflow in an agro-forest sub-catchment and the entire catchment. The hydrograph separation results using the Fmax(C1)/Fmax(C2) ratio can be used to support the optimization of water resource management and the quantification of pollutant loadings from major water sources to streams at the catchment scale.

Effects of Straw Return and Moisture Condition on Temporal Changes of DOM Composition and Cd Speciation in Polluted Farmland Soil.

Straw return can improve soil quality and change the mobility and bioavailability of pollutants in soil. Elevated cadmium (Cd) contents in farmland soils were often reported. However, the impacts of straw-derived dissolved organic matter (DOM) on Cd speciation in soil remain poorly understood. In this study, the effects of straw return and moisture condition on temporal changes of DOM composition and Cd speciation in farmland soils were explored through a laboratory incubation experiment. The humified components of DOM were negatively correlated with exchangeable, carbonate-bound, and Fe-Mn oxide-bound Cd (p < 0.01), while its protein-like component was negatively correlated with residual Cd (p < 0.01). It was found that selected fluorescence parameters could be used to predict temporal changes of Cd geochemical fractions. Straw addition led to increases in soil DOM content during the first three days of the incubation. Flooding should be avoided in the first three days following the straw application to reduce the risk of DOM-facilitated Cd mobilization.

Association Between Serum Asprosin and Diabetic Nephropathy in Patients with Type 2 Diabetes Mellitus in the Community: A Cross-Sectional Study.

Objective: To explore the association between serum asprosin and diabetic nephropathy (DN) in patients with type 2 diabetes mellitus (T2DM) in the community. Methods: In this cross-sectional study, we retrospectively collected the clinical data of T2DM patients from a community health service center in southeastern Shanxi Province between November 2019 and July 2021. Logistic regression analysis was used to calculate the odds ratio (OR) and the 95% confidence interval (95% CI) of asprosin levels on the risk of DN. Results: Among 498 T2DM patients included in this study, 221 had microalbuminuria, 105 had massive albuminuria, and 172 did not have any signs of nephropathy. Serum asprosin level was positively correlated with diastolic blood pressure, body mass index, triglycerides, aspartate aminotransferase, alanine aminotransferase, creatinine, ACR and albumin-to-creatinine ratio (all P < 0.05) and negatively correlated with low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fasting plasma glucose, HbA1c and estimated glomerular filtration rate (all P < 0.05). After adjusting for covariates, increased asprosin was associated with diabetic nephropathy (all OR = 2.560, 95% CI: 1.1592-4.116; P < 0.001). Conclusion: The risk of DN significantly increases with serum asprosin levels, especially among female patients.

[Effect of intercropping with Vicia faba on secondary metabolites and rhizosphere soil microbial diversity of Notopterygium incisum].

Rhizosphere soil microbial community and its diversity are important for the structure and functions of medicinal plant ecosystem. In this study, based on high-throughput sequencing, rhizosphere soil microbial diversity, and yield and quality of rhizome and root of Notopterygium incisum cultivated alone(control, CK) and intercropped with Vicia faba(QH) were analyzed, which is expected to lay a basis for optimization of the cultivation mode and ecological production of N. incisum. RESULTS:: showed that the rhizosphere soil bacteria of N. incisum were dominated by Proteobacteria and Bacteroides, with the relative abundance of 50.38%-51.95% and 16.36%-17.02%, respectively. Soil bacterial community at the phylum level was not significantly different between CK and QH. At the genus level, the relative abundance of MND1(3.54%), Spinstomonas(3.50%), Nitrospira(1.53%), and Rhizobacter(1.05%) was significantly higher and that of Gemmatimonas, Candidatus＿Solibacter, and Bryophytes was lower in QH treatment than in the CK. The plant height, leaf length, leaf width, and petiole length of N. incisum in QH treatment was significantly increased and the underground biomass rose by 71.43% compared with those in the CK. Thus, intercropping with V. faba promoted the aboveground growth of N. incisum and improved the yield of root and rhizome. Moreover, the content of notopterol and isoimperatorin increased by 37.96% and 4.09% in QH treatment, respectively, indicating that the intercropping with V. faba boosted the accumulation of secondary metabolites in N. incisum. Pearson's correlation analysis showed that the soil bacterial community was mainly influenced by the soil factors including the content of soil available nutrients, soil organic matter, pH value, and soil water. The influence was in the order: total potassium>total nitrogen>pH>organic matter>available potassium>soil water content>available nitrogen>available phosphorus. In conclusion, the intercropping with V. faba altered soil microenvironment and also increased the yield and accumulation of secondary metabolites of N. incisum, which is a promising ecological planting model for N. incisum.

Distinct aggregate stratification of antibiotic resistome in farmland soil with long-term manure application.

Agricultural soils, which are closely linked to human health via food supply, have been recognized as an important reservoir for antibiotic resistance genes (ARGs). However, there is still a lack of knowledge regarding the role of soil aggregates in shaping ARG profile. In this study, we collected soils from long-term experimental farmland plots receiving inorganic and/or organic fertilizers and examined the patterns of antibiotic resistome distribution among differently sized soil aggregates using high-throughput quantitative polymerase chain reaction (HT-qPCR). Our results showed that the distribution of soil ARGs could be affected by manure application and aggregate size individually but not interactively. More diverse and abundant ARGs were found in the manured soils, compared to the non-manured soils. The aggregate size fraction of <53 µm exhibited the highest diversity and abundance of ARGs. Variation partitioning analysis revealed that soil traits, mobile genetic elements, and bacterial community collectively contributed to the variation of soil antibiotic resistance. The knowledge about aggregation stratification of soil ARGs obtained in this study is fundamental and essential to understanding the fate of soil ARGs at the microscale.

Dynamics and sources of colloids in shallow groundwater in lowland wells and fracture flow in sloping farmland.

Field-scale studies of natural colloid mobilization and transport in finely fractured aquifer as well as the source identification of groundwater colloids are of great importance to the safety of shallow groundwater. In this study, the daily monitoring of fracture flow from a sloping farmland plot and the biweekly monitoring of three lowland shallow wells within the same catchment were carried out simultaneously in 2013. The effects of physicochemical perturbations on groundwater colloid dynamics were explored in detail using partial redundancy analysis, structural equation modeling, Pearson correlation and multi-linear regression analyses. The characterization and source identification of groundwater colloids were addressed via multiple parameters. The daily colloid concentration in the fracture flow varied between 0.54 and 31.90 mg/L (1.64 mg/L on average). Unique periods of high colloid concentration (5.59 mg/L on average) occurred during the initially generated flow following the dry season. In comparison, a narrower colloid concentration range of 0.24-11.66 mg/L was observed in the lowland shallow wells, with a smaller temporal variation than that of the fracture flow. A low percentage (2.4-7.0%) of colloids and a high percentage (47.7-92.0%) of coarse particles (2-10 µm) were present in the lowland well water. Hydraulic perturbation by rainwater infiltration in the sloping farmland was the dominant mechanism for colloid mobilization in general; this effect retreated to secondary importance behind chemical perturbations (pH, Mg2+ and DOC) at low flow discharges (<1.3 L/min). In contrast, water chemistry (e.g., EC, cations and DOC concentrations) exhibited a major effect on colloid dynamics in the water of the lowland wells, except for the extremely high-salinity water of one well, in which water temperature showed a negative dominant influence on colloid stability. The combined use of multiple parameters (e.g., mineral composition and organic matter, calcium carbonate and δ13C contents) traced groundwater colloids to the shallow soil in the upper farmlands. It is strongly advised that in finely fractured aquifers within agricultural catchments, not only the small colloids but also the coarse particles in the size range of 2-10 µm should be monitored in case of colloid-associated contamination from agricultural wastes e.g., N, P, pesticides and/or heavy metals, especially at the early stages of the rainy seasons.

Effect of long-term manure slurry application on the occurrence of antibiotic resistance genes in arable purple soil (entisol).

The application of animal manure is a highly recommended traditional agricultural practice for soils of relatively low fertility. However, for the farmland purple soils that are widely distributed in the upper Yangtze River region, little knowledge has been established in previous studies about the changes in the antibiotic resistome upon manure amendment. In the present study, the impact of long-term pig manure slurry application on the occurrence of antibiotic resistance genes (ARGs) and bacterial community was assessed in arable calcareous purple soil using high-throughput quantitative polymerase chain reaction and Illumina sequencing. Four treatments, including a non-fertilization control (CK) and pig manure (OM), OM plus mineral N fertilizer (OMN) and OM plus mineral NPK fertilizer (OMNPK) treatments were investigated. Across all the soil samples receiving different treatments, a total of 139 unique ARGs and 6 mobile genetic element genes were detected, with multidrug and beta-lactam the two most dominant types of ARGs. The results of the principal coordinate analysis (PCoA) suggest that the profiles of soil ARGs in the two treatments of OM combined with mineral fertilizer(s) (i.e., OMN and OMNPK) were similar to those in the control treatment, while the soil receiving only pig manure application had a different pattern of ARGs from the soils in the other three treatments. A clear reduction of soil ARGs was observed in the OM treatment. Significant and positive relationships were found not only among ARGs but also between mobile genetic elements (MGEs) and ARGs. However, no significant relationships were detected between ARG patterns and bacterial community composition. These results imply that the long-term application of pig manure slurry to purple soil does not lead to the prevalence of ARGs; however, the potential for the horizontal transfer of ARGs in calcareous purple soil should not be ignored.

Concentration and spectroscopic characteristics of DOM in surface runoff and fracture flow in a cropland plot of a loamy soil.

Being crucial for predicting the impact of source inputs on a watershed in rainfall events, an understanding of the dynamics and characteristics of dissolved organic matter (DOM) export from the soil under particular land use types, particularly those associated with underground flows is still largely lacking. A field study was carried out using a 1500m2 slope farmland plot in the hilly area of Sichuan Basin, Southwest China. The discharge of surface runoff and fracture flow was recorded and samples were collected in four representative rainfall events. For DOM characterization, concentration of dissolved organic carbon (DOC) and absorbance/excitation-emission matrix (EEM) fluorescence were analyzed. Soil water potential was also determined using tensiometers for understanding the runoff generation mechanisms. The DOC values for both surface and fracture flow showed significant responses to rainfall, with hydrological path being the primary factor in determining DOM dynamics. EEM-PARAFAC analyses indicated that the soil DOM mainly consisted of two terrestrial humic-like components with peaks located at Ex/Em 270(380)/480nm (C1) and 250(320)/410nm (C2), respectively. Concentrations of these components also responded strongly to rainfall, fluctuating in good agreement with the corresponding DOCs. Although there was no change in the presence of the components themselves, their relative distributions varied during precipitation, with the C1/C2 ratio increasing with the proportion of soil pre-event water. As the dynamic changes of soil DOM characteristics can be successfully captured using spectroscopic techniques, they may serve as a tracer for understanding hydrological paths based on their potential correlations with water source differences during rains.

Novel tracer method to measure isotopic labeled gas-phase nitrous acid (HO15NO) in biogeochemical studies.

Gaseous nitrous acid (HONO), the protonated form of nitrite, contributes up to ∼60% to the primary formation of hydroxyl radical (OH), which is a key oxidant in the degradation of most air pollutants. Field measurements and modeling studies indicate a large unknown source of HONO during daytime. Here, we developed a new tracer method based on gas-phase stripping-derivatization coupled to liquid chromatography-mass spectrometry (LC-MS) to measure the 15N relative exceedance, ψ(15N), of HONO in the gas-phase. Gaseous HONO is quantitatively collected and transferred to an azo dye, purified by solid phase extraction (SPE), and analyzed using high performance liquid chromatography coupled to mass spectrometry (HPLC-MS). In the optimal working range of ψ(15N)=0.2-0.5, the relative standard deviation of ψ(15N) is <4%. The optimum pH and solvents for extraction by SPE and potential interferences are discussed. The method was applied to measure HO15NO emissions from soil in a dynamic chamber with and without spiking 15) labeled urea. The identification of HO15NO from soil with 15N urea addition confirmed biogenic emissions of HONO from soil. The method enables a new approach of studying the formation pathways of HONO and its role for atmospheric chemistry (e.g., ozone formation) and environmental tracer studies on the formation and conversion of gaseous HONO or aqueous NO2- as part of the biogeochemical nitrogen cycle, e.g., in the investigation of fertilization effects on soil HONO emissions and microbiological conversion of NO2- in the hydrosphere.