Search Results (87)

BeiDou navigation satellite system (BDS) precise point positioning (PPP)-B2b has significant potential for application in meteorological fields, such as standalone water vapor monitoring in depopulated area without Internet. In this study, the practical ability of water vapor monitoring using the BDS PPP-B2b service is illustrated through a continuously operated water vapor monitoring system in Wuhan, China, with a 25-day experiment in 2025. Original observations from the Global Positioning System (GPS) and BDS are collected and processed in the near real-time (NRT) mode using ephemeris from the PPP-B2b service. Precipitable water vapor PWV monitored with B2b ephemeris are evaluated with radiosonde and ERA5 reanalysis, respectively. Taking PWV from radiosonde observations as the reference, RMS of PWV based on B2b ephemeris varies from 3.71 to 4.66 mm for different satellite combinations. While those values are with a range from 3.95 to 4.55 mm when compared with ERA5 reanalysis. These values are similar to those processed with the real-time ephemeris from the China Academy of Science (CAS). In general, this study demonstrates that the practical accuracy of water vapor monitored based on the BDS PPP-B2b service can meet the basic demand for operational meteorology for the first time. This will provide a scientific reference for its wide promotion to meteorological applications in the near future. Full article

In recent years, extensive attention has been paid to advanced oxidation processes (AOPs) with peracetic acid (PAA), a widely used disinfectant, using transition metal ions for the degradation of organic contaminants within water environments. Mn(II) has been widely used as an effective homogeneous transition metal catalyst for oxidant activation, but it has shown poor performances with PAA. Since the stability of manganese species can be enhanced through the addition of ligands, this study systematically investigated a novel AOP for the oxidation of carbamazepine (CBZ) using an Mn(II)/PAA system with several different ligands added. The reactive species were explored through UV-vis spectrometry, scavengers, and probe compounds. The results suggest that Mn(III)–ligand complexes and other high-valent Mn species (Mn(V)) were generated and contributed obviously toward efficient CBZ oxidation, while radicals like CH₃CO₂^• and CH₃CO₃^• were minor contributors. The oxidation efficiency of Mn(II)/PAA/ligands depended highly on ligand species, as ethylene diamine tetraacetic acid (EDTA) and oxalate (SO) could promote the oxidation of CBZ, while pyrophosphate (PPP) showed modest enhancement. The results obtained here might contribute to the removal of residue pharmaceuticals under manganese-rich waters and also shed light on PAA-based AOPs that could help broaden our present knowledge of manganese chemistry for decontamination in water treatment. Full article

With the increasing demand for near real-time atmospheric water vapor monitoring, this study evaluates the performance of the open-source PRIDE PPP-AR software (version 3.0.5) for retrieving Zenith Total Delay (ZTD) and Integrated Water Vapor (IWV) over the African continent over a one-year period. PRIDE PPP-AR is compared with established PPP-AR and PPP solutions, including CSRS-PPP, IGN-PPP, and NGL and using GipsyX, ERA5, and IGS products as references. A robust methodology combining time series processing and statistical evaluation was adopted. Multiple tools were leveraged to ensure a comprehensive performance analysis of GNSS data from seven stations in Africa, where such studies remain scarce. The results show that PRIDE PPP-AR achieves ZTD accuracy comparable to GipsyX (RMSE < 6 mm, R² ≈ 0.99) and performs at a similar level to NGL and CSRS-PPP. Compared to the other solutions, PRIDE PPP-AR has an accuracy similar to CSRS-PPP and NGL, but slightly better than IGN-PPP, in line with ERA5 and IGS references. For IWV retrieval, comparisons with ERA5 indicate RMSE values of about 1.5 to 2.7 kg/m², depending on station location and climatic conditions. IWV variability tends to increase towards the equator, where the recorded fluctuations are higher than in subtropical zones. In addition, collocated radiosonde (RS) measurements in Abidjan confirm good agreement, further validating the reliability of the software. This study highlights the potential of GNSS meteorology, in providing reliable spatiotemporal IWV monitoring and indicates that the PRIDE PPP-AR is ready for the high precision meteorological applications in African regions. These results offer promising prospects for spatiotemporal studies through African multi-GNSS networks and the PRIDE PPP-AR approach. Full article

Toona sinensis (A. Juss.) Roem, classified under the Toona genus of the Meliaceae family, is a fast-growing, woody species endemic to China, valued as both a vegetable crop and medicinal plant. Its seeds achieve rapid germination through a cascade of interconnected physiological, metabolic, and hormonal adaptations. Initially, physiological hydration is driven and accelerated by only two distinct phases of water imbibition. This hydration surge triggers storage reserve mobilization, with soluble sugars, proteins, and lipids undergoing rapid degradation during imbibition, while starch catabolism proceeds gradually—a pattern mirrored by progressive increases in enzymatic activities (amylase, protease, and acid phosphodiesterase (ACP)) that correlate with reserve reallocation. Concurrently, a metabolic shift from glycolysis to the pentose phosphate pathway (PPP) optimizes energy utilization, supporting germination acceleration. These biochemical changes are orchestrated by hormonal coordination: elevated gibberellin A₃ (GA₃), zeatin riboside (ZR), and indole-3-acetic acid (IAA) levels, coupled with rising GA₃/ABA, IAA/ABA, and ZR/ABA ratios, temporally aligned with germination progression. Finally, structural evidence confirms successful germination completion, as cotyledon lipid droplet breakdown and starch granule synthesis directly correlate with embryonic elongation. Together, these mechanisms underscore T. sinensis’ adaptive strategy, integrating physiological plasticity, metabolic flexibility, and endocrine precision to ensure efficient germination. Full article

The public–private partnerships (PPP) mode is very popular in public infrastructure projects. The PPP model for sponge city construction (SCC) provides an effective way to curb and manage the increasingly serious ecological water problems in China. The quantitative evaluation of value for money (VFM) is an evaluation method that obtains quantitative values through a certain calculation process. However, the current studies lack a dynamic quantitative evaluation of VFM for the entire life cycle of SCC PPP projects, and cannot observe the impact of key factors on the VFM value. By constructing a system dynamics (SD) model for the VFM quantitative evaluation of SCC PPP projects from the perspective of the whole life cycle, this study can intuitively and transparently observe the impact of key factors (such as discount rate and profit margin) on the evaluation results and feasibility of adopting a PPP model in the project, offering policymakers a tool to mitigate the risks of “Pseudo-PPP” projects. After collecting cases in Anhui province from the China PPP Center, this study constructed a life cycle VFM quantitative evaluation system dynamics model suitable for SCC PPP projects that consist of the public sector comparison (PSC) value and PPP value. The results indicate that the system dynamics model can be effectively applied to the dynamic quantitative evaluation of SCC PPP projects and clarify the influence degree on and sensitivity of various factors to the VFM value. Specifically, when the discount rate increases, the decrease in the PPP value is greater than that in the PSC value, leading to an increase in the VFM value. Moreover, a reasonable profit margin is more sensitive to the VFM value and decreases as the reasonable profit margin increases. In addition, choosing different availability service fee calculation methods will result in varying the adjustment range to a reasonable profit margin that drives the adoption of VFM quantitative evaluation. These research findings have provided a viable dynamic research methodology for the quantitative VFM evaluation of SCC PPP projects. This methodology enables the dynamic visualization and easy determination of the acceptable ranges for relevant factors, offers rational policy recommendations for the quantitative evaluation of key factor values, and thereby effectively prevents PPP project violations, promoting fair and reasonable cooperation between governments and private enterprises. Full article

As the discharge points of domestic sewage in rural areas are scattered with large fluctuations, constructed wetlands (CWs) are of great effectiveness in treating rural domestic wastewater. In this paper, horizontal subsurface flow modular constructed wetlands (HSSF-MCWs) with different filler combinations and plant species were constructed to analyze the pollutant removal effect on rural domestic wastewater. According to the fuzzy comprehensive evaluation method, the purification effect of the systems on rural domestic wastewater was evaluated for the selection of the best system. The decentralized rural domestic sewage treatment PPP project (Phase III) in Changshu was also monitored for field application. The results indicated that the red brick–volcanic rock (RB-VR) combination showed the best comprehensive removal effect on rural domestic wastewater, with the highest average removal rate of ammonia nitrogen (NH₄⁺-N 81.0 ± 2.5%) and total nitrogen (TN 64.5 ± 3.4%). The fuzzy comprehensive index (FCI) of the RB-VR systems with four rural plants ranged from 2.60 to 3.74, in which Myriophyllum elatinoides Gaudich. showed the optimum long-term purification effect. The water quality and economic analysis results of the pilot project in Changshu indicated that the overall influent concentration was low with large fluctuations, and the qualified effluent rate was relatively low. Moreover, the equipment investment accounted for 51.24% of the overall construction investment of the project, so more economical equipment (1 m³/day and 20 m³/day) should be adopted in rural domestic wastewater treatment. Full article

This article aims to examine the real-time precise point positioning (PPP) solution’s accuracy utilizing the low-cost dual-frequency multi-constellation U-blox ZED-F9P module and real-time GNSS orbit and clock products from five analysis centers, including Bundesamt für Kartographie und Geodäsie (BKG), Centre National d’Etudes Spatiales (CNES), International GNSS Service (IGS), Geo Forschungs Zentrum (GFZ), and GNSS research center of Wuhan University (WHU). Three-hour static quad-constellation GNSS measurements are collected from ZED-F9P modules and geodetic grade Trimble R4s receivers over a reference station in Aswan City, Egypt, for a period of three consecutive days. Since a multi-GNSS PPP processing model is applied in the majority of the previous studies, this study employs the single-constellation GNSS PPP solution to process the acquired datasets. Different single-constellation GNSS PPP scenarios are adopted, namely, GPS PPP, GLONASS PPP, Galileo PPP, and BeiDou PPP models. The obtained PPP solutions from the low-cost module are validated for the positioning and precipitable water vapor (PWV) domains. To provide a reference positioning solution, the post-processed dual-frequency geodetic-grade GNSS PPP solution is applied; additionally, as the station under investigation is not a part of the IGS reference station network, a new technique is proposed to estimate reference PWV values. The findings reveal that the GPS and Galileo 3D position’s accuracy is within the decimeter level, while it is within the meter level for both the GLONASS and BeiDou models. Additionally, millimeter-level PWV precision is obtained from the four PPP models. Full article

The optimization of the prickly pear peel (PPP) dehydration temperature was addressed. Two indicators of efficiency were used to select the optimal dehydration temperature: one related to the process productivity, another to the energy consumption. To calculate them the PPP dehydration kinetics were measured at three different temperatures (i.e., 50, 60, and 70 °C) along with the energy consumption of the process. A mathematical model was used to fit the dehydration kinetics. The influence of the temperature on the kinetics was assessed by analyzing the dependence of the fitting parameters on the dehydration temperature. It was found that both the kinetic parameters and the equilibrium parameter depend on the temperature through an exponential-type equation. The model was also used to calculate both the process productivity and the average energy consumed by the dehydration cabinet per grams of evaporated water when 99% dehydration is reached. The two efficiency indicators suggested that the optimal drying temperature is 70 °C, both being the indicators decreasing function of the temperature. Full article

Foreign capital has dominated over half of the public–private partnership (PPP) projects in developing countries over the past three decades. As such, attracting and regulating foreign participation in water PPP projects presents a critical challenge for both practitioners and scholars. Using a dataset of 2024 water PPP projects from 1994 to 2021, this study investigates foreign participation and its fall in China’s water PPP projects. Our findings highlight three key points: First, the proportion of projects undertaken by foreign capital decreased from 100% to less than 0.5%, with Chinese domestic capital taking its place. Second, resource dependence on foreign capital and the local government’s need for control lead to four types of foreign participation: financing water plants under user-pays, financing and operating water utilities under government-pays, participating with mainly an O&M role, and nearly no participation. Third, a better balance between efficiency gains and control needs via cooperation with domestic capital by local governments had driven the decline in foreign participation. This study makes two key contributions: (1) it is one of the pioneer studies on systematically tracing the evolution of foreign participation in PPP projects, and (2) it explains the fall of foreign participation from a local government perspective, complementing market-based explanations. Full article

Policies aimed at reducing plant protection products (PPPs) are part of the UN’s 2030 Agenda for Sustainable Development. Sustainable management of PPPs is crucial for soil health, biodiversity, and ecosystem services, including food provision. While PPPs can control pests and enhance agricultural yields, they also pose environmental and health risks by contaminating water, soil, and non-target organisms through airborne drift. Investigating innovative and more sustainable distribution methods can support sustainability goals. This study aimed to evaluate the potential impact of the pesticide Spintor^® Fly on non-target soil organisms in olive orchards comparing two spraying methods: a traditional Casotti^® pump mounted on a tractor and an innovative Unmanned Aerial Vehicle (UAV) developed for the project. The study was conducted in 2021 in an organic olive orchard, which was divided into two plots: a Casotti-treated plot (CAS) and a drone-treated plot (DRO). A strip of uncultivated land at the edge of the orchard was used as a (non-treated) control plot (CAP). The impact on native soil microarthropod communities was assessed using the arthropod-based Soil Biological Quality Index (QBS-ar) and Bait Lamina Test (BLT). Soil samples were collected for earthworm avoidance tests and soil chemical–physical analysis. The results obtained with QBS-ar and BLT indicated no significant differences between DRO and CAS, in both sampling periods (pre- and post-treatment). However, DRO generally exhibited slightly better performance than CAS. The avoidance behaviour was confirmed for both CAS and DRO, although it was lower for the latter. Overall, drone aerial spray performed slightly better, suggesting a potentially lower impact on soil communities. Our results provide initial clues for the sustainable use of drones in agriculture with no increased risks for soil health compared to traditional methods. Further long-term studies should be conducted to validate these findings and possibly confirm the long-term benefits of drone applications compared to traditional methods. Full article

The Global Navigation Satellite System (GNSS) has made important progress in Earth observation and applications. With the successful design of the BeiDou Navigation Satellite System (BDS), four global navigation satellite systems are available worldwide, together with Galileo, GLONASS, and GPS. These systems have been widely employed in positioning, navigation, and timing (PNT). Furthermore, GNSS refraction, reflection, and scattering signals can remotely sense the Earth’s surface and atmosphere with powerful implications for environmental remote sensing. In this paper, the recent developments and new application progress of multi-GNSS in Earth observation are presented and reviewed, including the methods of BDS/GNSS for Earth observations, GNSS navigation and positioning performance (e.g., GNSS-PPP and GNSS-NRTK), GNSS ionospheric modelling and space weather monitoring, GNSS meteorology, and GNSS-reflectometry and its applications. For instance, the static Precise Point Positioning (PPP) precision of most MGEX stations was improved by 35.1%, 18.7%, and 8.7% in the east, north, and upward directions, respectively, with PPP ambiguity resolution (AR) based on factor graph optimization. A two-layer ionospheric model was constructed using IGS station data through three-dimensional ionospheric model constraints and TEC accuracy was increased by about 20–27% with the GIM model. Ten-minute water level change with centimeter-level accuracy was estimated with ground-based multiple GNSS-R data based on a weighted iterative least-squares method. Furthermore, a cyclone and its positions were detected by utilizing the GNSS-reflectometry from the space-borne Cyclone GNSS (CYGNSS) mission. Over the years, GNSS has become a dominant technology among Earth observation with powerful applications, not only for conventional positioning, navigation and timing techniques, but also for integrated remote sensing solutions, such as monitoring typhoons, river water level changes, geological geohazard warnings, low-altitude UAV navigation, etc., due to its high performance, low cost, all time and all weather. Full article

The Hindu Kush Himalayan (HKH) region, known as the “water tower of the world,” is experiencing severe water scarcity due to declining discharge of spring water across the HKH region. This decline is driven by climate change, unsustainable human activities, and rising water demand, leading to significant impacts on rural agriculture, urban migration, and socio-economic stability. This expansive review judiciously combines both the researchers’ experiences and a traditional literature review. This review investigates the factors behind reduced spring discharge and advocates for a transdisciplinary approach to address the issue. It stresses integrating scientific knowledge with community-based interventions, recognizing that water management involves not just technical solutions but also human values, behaviors, and political considerations. The paper explores the benefits of public–private partnerships (PPPs) and participatory approaches for large-scale spring rejuvenation. By combining the strengths of both sectors and engaging local communities, sustainable spring water management can be achieved through collaborative and inclusive strategies. It also highlights the need for capacity development and knowledge transfer, including training local hydrogeologists, mapping recharge areas, and implementing sustainable land use practices. In summary, the review offers insights and recommendations for tackling declining spring discharge in the HKH region. By promoting a transdisciplinary, community-centric approach, it aims to support policymakers, researchers, and practitioners in ensuring the sustainable management of water resources and contributing to the United Nations Sustainable Development Goals (SDGs). Full article

Adjuvants alter the physical–chemical properties of pesticide formulations, influencing either the droplet size or drift phenomenon. Selecting the appropriate adjuvant and understanding its characteristics can contribute to the efficiency of Plant Protection Product (PPP) application. This reduces drift losses and promotes better deposition on the crop. The objective of this study was to evaluate the effects of four commercial adjuvants based on mineral oil (Agefix and Assist), vegetable oil (Aureo), and polymer (BREAK-THRU) on the physical–chemical properties (surface tension, contact angle, volumetric mass, electrical conductivity, and pH), droplet size, and drift, using pure water as the control treatment (no adjuvant). Surface tension and contact angle were measured with a DSA30 droplet shape analyzer, while droplet size measurements were determined through a laser diffraction particle analyzer (Malvern Spraytec), using a single flat fan spray nozzle (AXI 110 03) operating at 0.3 MPa. Drift reduction potential was evaluated inside a wind tunnel with an air speed of 2 m s⁻¹. All adjuvants reduced surface tension and contact angle compared to water. volumetric median diameter (VMD) increased for Aureo, Assist, and Agefix, generating coarse, medium, and medium droplets, respectively, while BREAK-THRU formed fine droplets, similar to those generated by water. Aureo had the greatest reduction in Relative Span Factor ($RSF$), with a reduction of 30.3%. Overall, Aureo, Assist, and Agefix adjuvants significantly reduced the percentage of droplets <100 µm and increased those >500 µm. Drift reduction potential was achieved for all adjuvants, with Aureo showing the highest reduction of 59.35%. The study confirms that selecting the appropriate adjuvant can improve PPP application and promote environmental sustainability in agricultural practices. Full article

Seed germination is crucial for plant survival, crop stand establishment, and achieving optimal grain yield. The main objective of this review is to explore the physiological and molecular mechanisms governing rice seed germination under aerobic (water stress) and anaerobic (hypoxic) conditions in direct-seeded rice (DSR) systems. Moreover, it discusses the recent genomic advancements and innovations to improve rice seed germination. Here, we discuss how coleoptile and mesocotyl elongation plays a vital role in anaerobic germination (AG) and the function of raised antioxidants, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in maintaining Reactive Oxygen Species (ROS), and malondialdehyde (MDA) homeostasis for stabilizing seed germination in water-scarce conditions. This study comprehensively highlights the functions and dynamics of phytohormones—GA (gibberellic acid) and ABA (abscisic acid)—key regulatory genes, transcription factors (TFs), key proteins, and regulatory metabolic pathways, including glycolysis, the pentose phosphate pathway (PPP), and the tricarboxylic acid cycle (TCA), in regulating seed germination under both conditions. Conventional agronomic and cultural practices, such as seed selection, seed priming, seed coating, and hardening, have proven to improve seed germination. Moreover, the utilization of molecular and novel approaches—such as clustered regularly interspaced short palindromic repeat (CRISPR-Cas9) mediated genome editing, marker-assisted selection (MAS), genome-wide associations studies (GWAS), single nucleotide polymorphisms (SNPs), multi-omics, RNA sequencing—combined with beneficial quantitative trait loci (QTLs) has expanded knowledge of crop genomics and inheritance. These advancements aid the development of specific traits for enhancing seed germination in DSR. Full article

Until now, no slow-release urea (SRU) fertilizer has been made using the screw press method and the powder of plant residues rich in polyphenols, which are considered eco-friendly materials due to some health benefits for agricultural soil. Therefore, the goal of this experiment was to synthesize a novel SRU fertilizer using “eco-friendly materials” and the “screw press method”. In order to achieve this goal, urea (U) was innovatively and highly intercalated between interlayers of impure montmorillonite (Mt) (bentonite) with the help of polyphenol-rich pomegranate peel powder (PPP) by a single-screw oil press machine. The experiment had five treatments, including a fixed ratio of U/Mt (4:1) with variable ratios of U/Mt/PPP (w/w), including 4:1:0 (F₁), 4:1:1 (F₂), 4:1:1.5 (F₃), and 4:1:2 (F₄). Control (U) and F₅ treatments (U/PPP at ratio of 4:1) were also included. These composites were fabricated using a single-screw oil press machine. The produced composites were characterized using FTIR, SEM, XRD, and TG analyses. The release pattern was studied using the White method. The XRD (low-angle) results revealed that the interlayer space of Mt increased from 12.3 Å in bentonite to 19.4 Å, 27.3 Å, 25.7 Å, and 0 Å in the F₁, F₂, F₃, and F₄ composites, respectively, which is an indicator of the high intercalation of U between the interlayers of Mt, especially in the F₂ treatment. The XRD (low- and normal-angle) analyses indicated that the two main reasons for the high intercalation in the F₂ treatment were, first, the complete conversion of urea from a crystalline to an amorphous state by PPP and, second, the increase in the interlayer space of Mt nano-sheets by PPP. It seems that PPP at a low concentration (F₂) can have a positive effect on the placement of U in the interlayer space, but at high concentrations (F₄), due to intensive pectin gelation, the space between the Mt layers grows until complete exfoliation. FTIR spectra and TG analysis also confirmed this hypothesis. SEM images revealed the formation of an intensive crosslink between U, Mt, and PPP. A release test in water revealed that only 10% of U in the F₂ treatment was released after 10 h, and 87% after 120 h, which indicates the satisfactory slow-release pattern of this composite. By comparing the results of the present study with the other SRUs reported in the literature, it can be concluded that the composite F₂, in addition to offering valuable polyphenol-rich plant materials, had an acceptable performance in the aspect of the U release pattern. Full article