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An undescribed isocoumarin derivative, named (±)-isothielavic acid (1), was isolated from the metabolites of endophytic fungus Thermothielavioides terrestris YB4 together with two known compounds 4(S)-thielavic acid (2) and thymine (3). The structure of (±)-isothielavic acid (1) was elucidated by comprehensive analysis of NMR spectroscopy and HRESIMS data as well as single-crystal X-ray diffraction experiment. Bioassay results indicated the weak antibacterial activity of compound 1 in vitro. [Display omitted] • A new isocoumarin derivative, given the trivial name (±)-isothielavic acid (1), was isolated from Thermothielavioides terrestris. • The isolated compound could be used as a scaffold for the synthesis of much more complex heterocyclic scaffolds. • Compound 1 exhibited antibacterial activity against Bacillus subtilis , Pseudomonas aeruginosa and Escherichia coli. [ABSTRACT FROM AUTHOR]

• A catchment plastic yield and transport model of multiple sources is proposed. • Model ensemble is adopted to estimate plastic sources and its uncertainty intervals. • The proposed model performs well for both plastic yield and outflow simulations. • Primary plastic sources are solid waste, agricultural film and impermeable surfaces. • Substantial plastic loads are retained in land system due to low loss coefficients. Plastic pollution has emerged as a global environmental concern, impacting both terrestrial and marine ecosystems. However, understanding of plastic sources and transport mechanism at the catchment scale remains limited. This study introduces a multi-source plastic yield and transport model, which integrates catchment economic activities, climate data, and hydrological processes. Model parameters were calibrated using a combination of field observations, existing literature, and statistical random sampling techniques. The model demonstrated robust performance in simulating both plastic yield and transport from 2010 to 2020 in the upper and middle Mulan River Catchment, located in southeast China. The annual average yield coefficients were found to closely align with existing estimations, and the riverine outflow exhibited a high correlation coefficient of 0.97, with biases ranging from -63.0 % to -21.4 % across all monitoring stations. The analysis reveals that, on average, 12.5 ± 2.5 % of the total plastic yield is transported to rivers annually, with solid waste identified as the primary source, accounting for 37.8 ± 20.7 % of the total load to rivers, followed by agricultural film (26.4 ± 9.8 %), impermeable surfaces (21.5 ± 10.3 %), urban and rural sewage (10.4 ± 5.0 % and 3.0 ± 1.5 %, respectively), and industrial wastewater (0.9 ± 0.7 %). The annual average outflow was estimated to between 9.3 and 43.0 ton/year (median: 23.1) at a 95 % confidence level. This study not only provides insights into the primary sources and transport pathways of plastic pollution at the catchment scale, but also offers a valuable tool for informing effective plastic pollution mitigation strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Phytoplankton is critical to river ecosystems. These organisms are sensitive to streamflow and water quality changes and, therefore, used to determine stability of river ecosystems, especially in regulated rivers. However, exactly how such disturbances alter spatial distribution of phytoplankton remains unclear, particularly during different seasons. A thorough understanding of these mechanisms is required to better analyze impact of environmental factors on regulated rivers. Given this, phytoplankton communities, streamflow, and water quality factors were assessed in areas sampled four times from 2015 to 2016 in upper and middle Huai River Basin. Biodiversity indices, as well as cluster and rank analyses, were used to (1) determine phytoplankton composition and distribution and (2) clarify impacts of key streamflow and water quality factors on such communities. It was found phytoplankton composition deteriorated over time, with phyla number decreasing from six to three. Moreover, proportion of Bacillariophyta increased from 51.83% to 68.13%. Phytoplankton in three regions, upstream region (Shannon-Wiener index 1.39–2.95), midstream region (0.70–4.55), and downstream region (0.22 to 2.97), were spatially clustered. The most impact factors impacting variation in composition and distribution were water quality factors and then hydrological factors. Of these, the most important factors in wet seasons were total nitrogen and maximum runoff, while ammonia nitrogen and low flow discharge were the most important factors during dry seasons. Streamflow and water quality contributed the most in midstream region, which was significantly affected by numbers of high and low flow. Contributions of these factors to downstream region were the strongest during dry seasons, which were significantly affected by numbers of low flow. Collectively, these results reveal significant impact of streamflow and water quality factors on phytoplankton deterioration in upper and middle Huai River Basin. Critically, this study provides scientific and technological support for increased biomonitoring and ecohydrological studies in regulated river basins. Graphical abstract Unlabelled Image Highlights • Phytoplankton deterioration results in high pollution and regulation. • Water quality factors contribute more than flow regimes indices. • High flow indices contribute to the deterioration and low flow indices restrain it. • Nitrogen nutrients take the most important role in phytoplankton communities. [ABSTRACT FROM AUTHOR]

Abstract Phosphate fertilizers are used in horticultural production to increase yields, but overuse can result in inefficient crop uptake and large loss of phosphorus (P). Soil amendments could potentially reduce the risk of P loss while maintaining high crop yield. The objective of this study was to investigate the effect of organic and inorganic amendments on P fractions in soils with different P levels (low, medium and high), and the underlying mechanisms. Five treatments were included: no amendment (CK), chemical fertilizers (CF), rice straw (FS), chicken manure compost (CM), and vermicompost (VM). Counterintuitively, the proportion of organic phosphorus (OP) tended to increase in the CF treatment, especially in soil with low P level. Results indicated that the change in the proportion of OP was mainly controlled by soil acid phosphomonoesterase, alkaline phosphomonoesterase and phosphate-solubilizing microorganisms. The proportion of available P increased in soil with low P level, but decreased in soil with high P level in the VM treatment. Non-labile P was preferentially formed in the VM treatment because of the high calcium content in vermicompost. Phosphates associated with aluminum (Al-P) were significantly higher in the CM treatment than in other treatments. This treatment also had a large presence of Pseudomonas and Streptomyces bacteria, which are capable of promoting the formation of Al-P. Our results indicated that mechanisms causing changes in soil P fractions were distinctly different among various amendments, and that vermicompost had the greatest potential to increase P supply in soil with low P level, and to decrease the risk of P loss in soil with high P level. Graphical abstract Unlabelled Image Highlights • Soil P fractions were investigated under different soil amendments. • Suitable amendments were proposed for soil with different P levels. • Chemical fertilizer addition tended to increase the proportion of soil organic P. • Vermicompost addition was superior in decreasing potential risk of P loss in soil with high P level. [ABSTRACT FROM AUTHOR]

By pot experiment method, this study investigated the role of plant hormone abscisic acid (ABA) in the foliar application of 10 μM lanthanum nitrate (La(NO 3 ) 3 )-regulated the biosynthesis, regeneration and degradation of vitamin C (Vc) and the content of Vc in the fruit of strawberry at different periods of growth and development. The results showed that La(NO 3 ) 3 significantly increased the content of Vc by increasingthe activities of recycling enzymes glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and biosynthetic enzyme L-galactono-1,4-lactone dehydrogenase (GalLDH), and decreasing the activities of recycling enzyme APX and degrading enzyme ascorbic acid oxidase (AAO). Compared with La(NO 3 ) 3 alone, applications of different ABA biosynthesis inhibitor sodium tungstate (Tu) all markedly decreased the activities of GR, MDHAR and GalLDH, and increased the activities of DHAR and APX, which resulted in the reduction in the content of Vc. Meanwhile, La(NO 3 ) 3 induced the production of ABA and Tu reversed the effect of La(NO 3 ) 3 on ABA content. Our results suggested that La(NO 3 ) 3 -induced ABA participated in the regulation of Vc content in the fruit of strawberry. [ABSTRACT FROM AUTHOR]

Understanding the water use strategy of crops is important for maintaining the stability of agricultural production and improving water use efficiency (WUE). Affected by a variety of water sources and hyper-arid climate, the characteristics of root water uptake (RWU) in seed maize are extremely complicated but underestimated in oasis farmlands with shallow groundwater. We hypothesized that isotope (δ2H and δ18O) measurements over three years coupled with a MixSIAR model would reveal the characteristics of RWU in maize. Stable water isotopes in oasis farmlands were continuously observed from 2019 to 2021. Over the growing season, the soil matrix potential increased with soil depth. The isotopes in stem water had high similarity to groundwater, irrigation water, and soil water. The contributions of soil water in 0–20 cm, 20–40 cm, 40–60 cm, and 60–100 cm soil layers to RWU in maize were 29.7%, 12.2%, 14.8%, and 43.3%, respectively. From the jointing stage to the dough stage, the depth of RWU in maize was from shallow to deep; but after the dough stage, the depth of RWU in maize was from deep to shallow. Crops might prefer to absorb more groundwater and irrigation water in oasis farmlands with shallow groundwater. This study provides insights into crop water uptake and agricultural water management in hyper-arid regions. • Root uptake patterns in seed maize were investigated using δ2H and δ18O in hyper-arid regions. • The depth of RWU in maize was "shallow-deep-shallow" pattern with the growing periods. • The contributions of soil water in 0–20 cm and 60–100 cm to RWU in maize were 29.7% and 43.3%. • Maize used more groundwater and irrigation water in oasis farmlands. [ABSTRACT FROM AUTHOR]

Water and related environmental problems have become a key barrier to the sustainable development of China, where multiple uses of water and urban water management are two significant means to sustain urban development and the ecological restoration of rivers. A new assessment approach and water system model were developed to estimate eco-water or the volume of water essential for maintaining healthy and sustainable urban river ecosystems under various natural landscapes and water quality objectives. Moreover, multiple scenario analysis was adopted to explore the influences of water quality on eco-water management. The Yongding River in Beijing was selected as a case study. The results showed that the eco-water volume was 0.079, 0.073 and 0.067 billion m 3 /a under high, medium and low objectives without water quality requirements, and 0.112, 0.107 and 0.101 billion m 3 /a further considering water quality. The water residence times anticipated under each development scenario were 34.8, 37.5 and 41.5 d, which were 13.0%, 14.5% and 13.6% longer than those when water quality was considered. Better water quality could be achieved by implementing water diversions. The comprehensive implementation of water diversion projects could increase the rate of water discharge by 45.1%, decrease the permanganate concentration by 16.1%, and reduce the water residence time by 28.9% on average. This study is expected to provide scientific bases for good water governance, prepare healthy water systems for sustainable communities, and provide a reference case to achieve multiple uses of water for human uses and ecological river restoration in water short areas in developing countries. [ABSTRACT FROM AUTHOR]

China frequently suffers from considerable and disastrous flash floods with wide areal coverage and high frequency. Obtaining useful information to support flash flood management and decision-making is challenging for massive flash flood events that vary greatly in spatio-temporal characteristics. In this study, hydrological modelling approach (CNFF) and cluster analysis were integrated to assess simulation reliability of entire flash flood processes including both hydrographs and behavior characteristics in a manner of similarity classification, rather than at event scale. A total of 207 hourly events from 13 mountainous catchments with diverse physiographic and meteorological characteristics across China were selected for study. Representative flash flood types were classified using normalized hydrographs with diverse spatio-temporal patterns by k -means clustering algorithm. For individual flash flood types, simulation reliability of CNFF was assessed in capturing corresponding hydrographs, seven behavior metrics measuring flash flood magnitude, intensity, occurrence time, flood timescale, rates of change and variability, and their uncertainties. Results showed that three (fast, intermediate and slow) flash flood types were identified from all the flash flood events with overall average silhouette index of 0.45. Hourly hydrographs of three flash flood types were well reproduced by CNFF, with absolute average relative error of runoff within 15% and Nash-Sutcliffe Efficiency above 0.55. All the behavior metrics were the most accurately reproduced for slow flash flood type with the least average relative root-mean-square error (0.30), followed by intermediate (0.52) and fast (0.58) types. Moreover, the slow flash flood type had the most reliable but greatest uncertainty interval of both hydrograph and behavior metrics, with average relative interval length being 1.24 and 71.96%, and 93.10% and 100% of observations contained in 95% confidence interval, respectively. This study provided efficient and detailed information for flash flood management, and extended application scope of hydrological models to encompass flash flood types and behavior metrics. Unlabelled Image • Both hydrograph and behavior metrics are simulated for similar flash flood types. • Fast, intermediate and slow flash flood types are grouped using massive hydrographs. • Hourly hydrograph is well simulated for three flash flood types and the most reliable for slow type. • Flood behavior metrics are the best and most reliably simulated for slow flash flood type. [ABSTRACT FROM AUTHOR]

Two new iridoid glucosides, named diffusosides A and B, were isolated from the aerial part of Hedyotis diffusa Willd. Their structures were elucidated by 1D-, 2D-NMR spectroscopic analysis and HRESIMS. These two compounds showed no cytotoxic activity against SMMC-7721, SW480, SW620, Bel7402, and HepG2 cells. [Copyright &y& Elsevier]

Understanding temporal and spatial changes in precipitation has far-reaching implications for watershed development and risk assessment under global climate change. In our study, temporal and spatial variability in precipitation concentration (PC) in Central Asia (CA) from 1980 to 2017, measured with the precipitation concentration index (PCI) and Gini Coefficient (GC), was analyzed using interpolated precipitation from the Climate Prediction Center (CPC) and National Centers for Environmental Prediction (NCEP). The results showed that: (1) interpolated precipitation increased significantly, with significant mutations (P <.5) mainly concentrated between 2000 and 2010; (2) the spatial distribution of the CPC PCI was opposite to that of the NCEP PCI, and fluctuations in CPC GC were larger than that of the NCEP, which indicated that the precipitation data from NCEP was more uniform over the year; (3) for two of three interpolation methods, CPC PC displayed significant mutations in southern CA between 1985 and 2005, while significant (P <.05) mutations in NCEP PC were relatively concentrated in southern CA between 1987 and 2005; (4) although the El Niño Modoki Index (EMI), Pacific Decadal Oscillation (PDO), Nino 3.4, and Southern Oscillation Index (SOI) displayed resonance relationships with CPC PCI, there were no significant abrupt changes in the resonance correlation. In the NCEP data, EMI, PDO, Nino 3.4, and North Atlantic Oscillation (NAO) led to mutations in the resonance relationship with PCI. Our research proved that the change in PC in CA had closely relationship with some teleconnection indices. • The characteristics from different product were different over Central Asia. • The mutations for different interpolated precipitation were different. • Precipitation concentration had a gradual trend in space over Central Asia. • More than one teleconnection index impacted on the precipitation concentration. [ABSTRACT FROM AUTHOR]

Under climate change, droughts are causing increasingly larger damages around the world, attracting the attention of governments and researchers. In this study, the terrestrial water storage anomalies (TWSA) obtained from a Gravity Recovery and Climate Experiment (GRACE) were coupled with precipitation, creating a Combined Climatological Deviation Index (CCDI). This index was used to analyze the drought events that occurred in the major basins of Central Asia between April 2002–June 2017. The main conclusions are as follows: (1) the certain but not significant (i.e., p >.05) impacts of precipitation were detected on the total water storage anomalies (TWSA) of three basins (i.e., Irtysh River Basin (IRB), Syr Darya Basin (SDB), and Amu Darya Basin (ADB)) that originate from the Tienshan Mountains based on the correlation coefficient between precipitation and terrestrial water storage (TWS); (2) the Drought Severity Index (DSI), the Palmer Drought Severity Index (PDSI), and the Standardized Precipitation Index over a 12-month scale (SPI12) were related to the CCDI in the major basins of Central Asia, suggesting that the CCDI can be applied effectively to assess the drought characteristics of these basins; (3) the most severe drought events detected by the CCDI in the IRB, SDB, and ADB occurred in 2012, 2014, and 2014, respectively. A humidification trend was observed for the IRB, while a drought trend was observed in the SDB and ADB. Therefore, it appears that the CCDI can be effectively applied to determine the severity of droughts, increase water-saving awareness, and avoid the effects of droughts. • Precipitation has little effect on TWS in Central Asia. • CCDI can character the drought events in Central Asia well. • The drought severity from CCDI was more severe than that from other traditional drought indices. • All the drought indices were discovered the obvious drought events in Central Asia during 2008–2009. [ABSTRACT FROM AUTHOR]

• Soil respiration including winter CO 2 efflux was studied in the desert-oasis region. • Annual soil CO 2 emissions varied from 176 to 918 g C m−2 across the study ecosystems. • The ratio of cold season CO 2 emissions to the annual was 6–15% across ecosystems. • Land use conversion influenced soil respiration across the desert-oasis ecoregion. Quantifying annual soil CO 2 emissions and the effects of physical and geochemical factors on soil CO 2 efflux will improve the carbon budget estimates, as well as enhance predictions of how soil CO 2 emission will response to climate change in arid areas. To data, variability in soil respiration rates caused by land use conversion in the desert-oasis ecoregion of Northwest China remains poorly characterized, especially the contribution of cold season (November-February) CO 2 emission. Soil respiration was measured in a Haloxylon ammodendron desert shrubland, a Zea mays cropland, a Populus gansuensis forest, and a Tamarix chinensis Lour wetland using a LI-COR 8100 Soil Respiration Observation System from April 2016 to March 2019. Annual soil CO 2 emissions totaled 176, 778, 918, and 397 g C m−2 in the desert shrubland, cropland, forest, and wetland, respectively. The ratio of cold season CO 2 emissions to the annual varied from 6 to 15% across ecosystems. Therefore, ignoring cold season CO 2 emissions would lead to underestimates of carbon losses in the desert-oasis ecoregion. The soil respiration rate at 10 °C was influenced by soil organic carbon content in all four ecosystems. In the cropland and forest, soil respiration rate was affected by the interaction of soil moisture and soil temperature, while in the wetland and desert shrubland, soil respiration was sensitive to a single factor, soil temperature. Land use conversion induced differences in organic matter accumulation, soil temperature, and soil moisture, and as a consequence, produced variability in soil respiration rates across the desert-oasis ecoregion. [ABSTRACT FROM AUTHOR]

• Straw incorporation changed the N effects on soil bacterial community composition. • Straw incorporation enhanced the cellulolysis function and relevant taxa abundance. • N fertilization stimulated most of the C transformation and N cycling processes. • Reducing N fertilization will not change microbial taxa profiles and functions. • The abundance of copiotrophic taxa decreased at the mid-growing season. Integrating nitrogen (N) fertilization with crop residue amendments is usually used to enhance soil nutrient levels and promote crop growth in regions with intensive agriculture. However, the interactive effects of straw incorporation and N fertilization on the abiotic and biological properties of soil are not fully understood, especially under field conditions at different crop growth stages. In this study, we estimated the dynamic changes in the soil physicochemical properties and bacterial communities in response to N fertilization, straw incorporation, and their combinations during the maize growing season in black soil region in Harbin, China. N fertilization increased the relative abundance of the typical copiotrophic bacterial taxa, Alphaproteobacteria, but reduced that of the oligotrophic group, Acidobacteria. The straw incorporation enhanced the relative abundance of Bacteroidetes and Gammaproteobacteria, within which a variety of cellulolysis-related species phylogenetically fell. Interestingly, the straw amendments changed the effects of N fertilization on the overall soil bacterial community composition, possibly by altering the soil total carbon, C/N ratio, fixed ammonium, and moisture level. N fertilization stimulated most of the carbon (C) transformation and N cycling processes, and the straw incorporation increased the cellulolysis, N fixation, ureolysis, ammonia oxidation and denitrification functions. There were no differences in the soil chemical properties, microbial taxa profiles or predicted functions between the conventional N fertilizer usage (high N level) and the optimized N fertilization management scheme (low N level), irrespective of straw incorporation, implying that moderately reducing the usage of N fertilizer will not change the ecosystem service and function in this organic matter-rich black soil region. The relative abundance of the copiotrophic bacterial taxa decreased at the mid-growing season, which might be caused by the low soil C and N availability. In contrast, the oligotrophic bacterial groups showed predominance at the mid-growing season, which might aim to mineralize soil organic matter to meet the growth needs of both the crops and the microbes. The nitrifiers (Nitrospirae) and nitrification process were sharply activated at the mid-growing season, especially under the straw amendment condition, inferring that the combination of straw application with N fertilizer could serve as an effective measure for improving soil fertility in Northeast China. The present study enhanced our knowledge on the dynamic changes in soil biotic and abiotic parameters in response to straw incorporation and N fertilization during the maize growing season. Still, this study provides a reference for designing an environmentally friendly fertilization strategy that both alleviates environmental stress and maintains a high crop yield in Northeast China. [ABSTRACT FROM AUTHOR]