Search

Single-stage partial nitration and anammox (PN/A) is achieved using a submerged dynamic membrane (DM-SBR) in this study. The DM-SBR was stably operated for 200 days, and the nitrogen removal efficiency (NRE) was sustained at 70.3 ± 7.2% at a nitrogen loading rate (NLR) ranging from 0.1 to 0.3kgN/m3/d with a hydraulic retention time (HRT) of 24 h. When the NLR was 0.2 kgN/m3/d, the NRE achieved was high as 80% with a low concentration of dissolved oxygen (DO) of 0.13 mg/L. In addition, the specific activity of anammox bacteria (AnAOB) and ammonia-oxidizing bacteria (AOB) reached was 2.72 and 16.80 gN/gVSS/d, respectively. The dynamic membrane (DM) intercepted the biomass due to the lamellar, intact, dense biofilm self-generated on the surface of the supporting material, which had an effluent turbidity of 10 NTU. The enriched anammox functional bacteria were Candidatus Jettenia, and the relative abundance was 11.06%. The AOB-like functional bacteria consisted primarily of Nitrosomonas, with a relative abundance of 2.76%, which ensured the nitrogen removal process reaction. This study provides a novel reactor configuration of the single-stage PN/A process in the view of practical applications.

As one of the components of root exudates, methyl 3-(4-hydroxyphenyl) propionate (MHPP) not only functions as a nitrification inhibitor in soil but also modulates plant growth and root system architecture (RSA); however, the physiological and molecular mechanisms underlying MHPP-mediated plant growth remain largely unclear. Here, we investigated the effects of MHPP treatment on growth and secondary metabolite accumulation by integrating physiology, transcriptome and metabolome analyses using perilla (Perilla frutescens), a type of medicinal and edible plant. MHPP reduces primary root growth but markedly induces lateral root formation in perilla seedlings. The full-length transcript sequencing combined with the comparative transcriptomic analysis revealed that the differential expression of genes involved in carbon/nitrogen metabolism and secondary metabolism contributed to the MHPP-mediated plant growth. An investigation of the differentially expressed genes showed that MHPP modulates the growth and metabolism of leaves and roots in distinct pathways. The genes involved in the phenylpropanoid metabolism pathway showed opposite expression patterns between the roots and leaves, thereby resulting in the differential accumulation of secondary metabolites in the roots and leaves. Furthermore, the differential expression of PER genes and elevated peroxidase activity in the MHPP-treated roots were responsible for modulating the equilibrium of ROS and the components of lignin and phenolic compounds, thereby affecting plant growth and secondary metabolite accumulation. MHPP modulates RSA and metabolite profiles and improves the contents of medicinal ingredients in perilla plants. These results suggested that the application of MHPP may represent a useful strategy for the medicinal plant cultivation.

The extract of crofton weed (Eupatorium adenophorum) inhibits seed germination and weed growth; however, the physiological mechanisms underlying the effect of crofton weed extract on the modulation of seedling growth and root system development remain largely unclear. In this study, we investigated the effects of the leaf extract of crofton weed (LECW) on primary root (PR) growth in maize seedlings. Treatment with LECW markedly inhibited seed germination and seedling growth in a dose-dependent manner. Physiological analysis indicated that the LECW induced reactive oxygen species (ROS) accumulation in root tips, thereby leading to cell swelling and deformation both in the root cap and elongation zone of root tips, finally leading to cell death in root border cells (RBCs) and PR growth inhibition. The LECW also inhibited pectin methyl esterase (PME) activity, thereby decreasing the RBC number. Taken together, our results indicated that the LECW inhibited PR growth by inducing ROS accumulation and subsequent cell death in RBCs. The present study provides a better understanding of how the LECW modifies root system development and provides insight for evaluating the toxicity of crofton weed extracts in plants.

Fine-scale population gridded datasets are of great significance in emergency response, resource allocation, and traffic planning. Many studies have developed fine-scale population spatialization m...

China has experienced greater and faster urbanization than any other country, and while coordinated regional development has been promoted, urbanization has also introduced various problems, such as an increased scarcity of land resources, uncontrolled demand for urban land, and disorderly development of urban fringes. Based on GIS, remote sensing data, and spatial statistics covering the period 1995–2015, this study identified the patterns, as well as spatial and temporal changes, with respect to urban land expansion in 367 mainland Chinese cities. Over this study period, the area of urban land in mainland China increased from 3.05 to 5.07 million km2, at an average annual growth rate of 2.56%. This urban land expansion typically occurred the fastest in medium-sized cities, followed by large cities, and then small cities, with megacities and megalopolises exhibiting the slowest expansion rates. Nearly 70% of the new urban land came from arable land, 11% from other built land, such as pre-existing rural settlements, and 15% from forests and grasslands. When considering marginal-, enclave-, and infill-type expansion patterns, growth in >80% of the 367 cities surveyed was dominated by marginal expansion patterns. Marginal and enclave expansion patterns were found to be becoming more prevalent, with infill-type expansion being seen less. The results of this study provide a theoretical basis and data support for urban spatial planning, the protection of farmland, and the promotion of urban land use efficiency, and can be used as guidance for regional urbanization planning.

Urban parks have been considered as an effective measure to mitigate the urban heat island (UHI) effects. Many studies have investigated the impacts of shape, size and interior components on the cold island effect (CIE) of parks, while little attention has been given to the impact of neighboring buildings. Thus, taking twenty-two parks in Beijing as samples, this study investigated the impacts of the neighboring building on the CIE of central parks. The results showed that the average land surface temperature (LST) of parks are 30.98 &deg, C in summer and &minus, 1.10 &deg, C in winter. Parks have a strong CIE in summer, and average cold island footprint (CIF) and LST difference are 0.15 km2 and 2.01 &deg, C higher than that in winter. The components of the building in the CIF of parks are dominated by middle-rise building (MRB), followed by low-rise building (LRB), and high-rise building (HRB) is the least dominant. The percentage of landscape (PLAND) and landscape shape index (LSI) of MRB, and perimeter area fractal dimension (PAFRAC) of LRB are significantly related to CIF in summer and winter. This study could extend scientific understanding of the impacts of neighboring buildings on the CIE of central parks, and could guide urban planners in mitigating the UHI effects through the rational allocation of buildings.

Spatially explicit information on electric power consumption (EPC) is crucial for effective electricity allocation and utilization. Many studies have estimated fine-scale spatial EPC based on remotely sensed nighttime light (NTL). However, the spatial non-stationary relationship between EPC and NTL at prefectural level tends to be overlooked in existing literature. In this study, a classification regression method to estimate the gridded EPC in China based on imaging NTL via a Visible Infrared Imaging Radiometer Suite (VIIRS) was described. In addition, owing to some inherent omissions in the VIIRS NTL data, the study has employed the cubic Hermite interpolation to produce a more appropriate NTL dataset for estimation. The proposed method was compared with ordinary least squares (OLS) and geographically weighted regression (GWR) approaches. The results showed that our proposed method outperformed OLS and GWR in relative error (RE) and mean absolute percentage error (MAPE). The desirable results benefited mainly from a reasonable classification scheme that fully considered the spatial non-stationary relationship between EPC and NTL. Thus, the analysis suggested that the proposed classification regression method would enhance the accuracy of the gridded EPC estimation and provide a valuable reference predictive model for electricity consumption.

A 200-day experiment was conducted to evaluate strategies for the stable performance and rapid inhibition recovery of a thermophilic reactor treating coffee wastes, waste activated sludge, and milk waste under a high organic loading rate (OLR) and the synergistic effects of microbes. Excessive accumulation of propionate was determined to be the main reason for the deterioration of the reactor, which resulted from reduced methanogenic activity. Supplementation of inoculum sludge led to the complete inhibition recovery of the reactor in fewer than 35 d by enhancing propionate degradation. The microelement and low concentration of sulfate ensured the stable performance of the reactor at OLR of 4.6 g-TS/L/d. The efficiency of organic matters and propionate degradation was also improved. The microbial community was analyzed by high-throughput sequencing targeting 16S rRNA to determine the relationship between microbial composition and reactor performance. Propionate markedly inhibited Methanosarcina, which dominated the stable state; meanwhile, Methanobacterium and Methanothermobacter were more tolerant and comprised more than 75% of total archaea at the inhibitory stage. The deterioration of the reactor led to a shift in the CH4 generation pathway from acetoclastic to hydrogenotrophic. Clostridiales was responsible for organic degradation at stable stages; however, almost all of the genera of Clostridiales could not survive at stage II and were replaced by Thermoanaerobacterales and Lactobacillales.

To understand the relationship between microbes and digester performance of high-frequency feeding CSTR, which could achieve stable CH4 production at high OLR by easing instantaneous feeding shock, attentions were paid on the variations of methanogenic capacity (MC) and microbial community with OLR increasing. Results showed that the MC for feedstock degradation could satisfy the need of effective conversion from feedstock to CH4 when the OLR remained below 16.4 g-TS/L/d. Furthermore, the MC for acetate, propionate and butyrate degradation increased by 73.8%, 303%, and 164%, respectively, with OLR increasing from 3.03 g-TS/L/d 12.6 g-TS/L/d. The evolution of both bacterial and archaeal communities provided additional information on the adaptation of functional microbes to environmental factors. The significant increase of abundance of Methanoculleus and Methanomassiliicoccus likely promoted the utilization of H2, thus facilitating syntrophic methanogenesis, and consequently ensuring efficient CH4 production in stable stage.

Soil erosion (SE) processes are closely related to natural conditions and human activities, posing a threat to environment and society. Identifying the human impact on regional SE changes is increasingly essential for pertinent SE management. Jiangxi province is studied here as a representative area of hilly-red-soil regions within southern China. The main objectives of this study were to investigate the changing trend of SE within Jiangxi and identify human impacts on regional SE change from the perspective of spatial differences, through a new approach based on a gravity-center model. Our results showed that SE status presented an overall amelioration from 1990 to 2015, while the average soil erosion modulus (SEM) declined from 864 to 281 Mg/(km2&middot, a). Compared to the situation under human and natural impacts, human-induced spatial differences of SE change demonstrated that the western and northwest regions showed stronger negative effects, the southern region shifted towards negative effects, the northeast region presented a much weaker negative effect. Our results indicated that 4 cities with strong negative effects need more attention in further SE management suited to their local conditions and development, and also suggested that the approach based on a gravity-center has potential for identifying the human impact on regional SE change from the perspective of spatial patterns.

This study elucidates volatile fatty acids (VFAs) accumulation reasons during organic solid wastes degradation via kinetics and thermodynamics assessments of degradation mechanisms of representative VFA (acetate, propionate, butyrate and valerate) under mesophilic (35 °C) and thermophilic (55 °C) conditions. Acetate exhibited the highest maximum microbial specific growth rates of 0.18 d−1 and 0.33 d−1 at mesophilic and thermophilic conditions, respectively, during the degradation process, followed by butyrate at 0.08 d−1 and 0.08 d−1. However, propionate showed a stronger inhibition to methanogenesis at thermophilic conditions, especially at the substrate concentration exceeding 5000 mg COD/L. The largest specific maximum methanogenic activity (SMA) decreased from 0.029 to 0.022 g CH4-COD/g-VSS/d. Furthermore, an inability of microorganisms to adapt to thermophilic propionate degradation conditions (at maximum lag time of 12 days) indicated substantial substrate inhibition. As an intermediate product of valerate degradation, the propionate degradation rate was considerably lower than that of valerate (0.036 g COD/d vs. 0.104 g COD/d). Hence, propionate caused a substantial rate limitation during the valerate degradation process under thermophilic conditions. In addition, under thermophilic conditions, valerate converted to methane via a long three-step syntrophic oxidation process. A large amount of hydrogen production accompanied this process. The inhibitory effect of propionate on methanogens and high hydrogen concentration (approximately 700 ppm) required time to subside. Thus, a 4-day plateau associated with a positive Gibbs free energy (1.45–2.11 kJ/mol) occurred during valerate degradation.

Yield gridded datasets are essential for agricultural land management, food security and harmonious human&ndash, land relationships. Many studies have developed yield spatialization models that are based on cropland areas. However, crop planting areas, phenological dates, and net primary production (NPP) have received minimal attention. This study proposes a novel method to simulate winter wheat yields in China from 2000 to 2015 using crop phenological datasets, phenological observations, and NPP. The results showed that the NPP in the growing season and statistical yield showed a significant positive correlation (R2 = 0.93, p &lt, 0.01). The mean prediction error of the gridded yield dataset was 12.01%. The relative errors of the gridded yield dataset for approximately half of the samples were between &minus, 10% and 10%. Furthermore, the yield distribution was high in the east and low in the west. The high yield was primarily concentrated in the North China Plain, while low yield was observed in eastern Gansu, central Shanxi, southern Hebei, and eastern Sichuan. From 2000 to 2015, the yield mainly showed an increasing trend in the study area, with the average rate of 0.17 t ha-1 yr-1, especially in the North China Plain. This study suggests that NPP is a key indicator to evaluate the yield of winter wheat. Furthermore, this method can be used to generate gridded yield maps along with providing credible and fundamental data for climate change and sustainable agricultural development.

The Colletotrichum musae and Fusarium semitectum Berk., Which often occur in banana after harvest were used as the targets. Three components with antibacterial activity extracted from the leaves of the plant were used as "fungicide". The antibacterial effect of the three component substances on the pathogens of anthracnose and shaft rot was studied. The results showed that the inhibitory rates of the components A, B and C at 2 mg / ml on the pathogens of banana anthracnose and shaft rot reached 82.53%, 79.91%, 78.30% and 82.2%, 78.69% and 81.17% respectively. The EC90 values of component A, B and C for banana anthracnose pathogens were 1.70, 1.85, and 1.69 mg / ml. Respectively, the EC90 values for banana shaft rot pathogens were 1.37, 1.38, and 1.64 mg / ml. The antibacterial effect of the three component substances on the pathogen of banana shaft rot was better than that of anthracnose. The three component substances have great potential for controlling post-harvest anthracnose and shaft rot of bananas.

As elicitors of terrestrial system change (e.g., land use transformation) through the introduction of anthropogenic causes, the spatial patterns and levels of roads might be more detrimental to the long-term health of ecosystems at a large scale than the road paving itself. This paper reveals the relationship between soil erosion and roads from a large-scale perspective in Jiangxi Province, China. Temporal and spatial distribution characteristics of artificial and natural drive factors of soil erosion alongside roads were addressed. It was found that, from 1990 to 2010, Jiangxi Province experienced an obvious reduction in soil erosion (the mean annual soil erosion rate decreased from 930.8 t·km−2·a−1 to 522.0 t·km−2·a−1), which was positively correlated with road density (p < 0.01). The maximum soil erosion reduction occurred at a distance of 0–1 km from the village roads. The order of soil erosion effects of the four levels of roads is: Village road > county road > provincial/national road. We emphasize that studying the indirect roles of roads in soil erosion is strongly dependent on a comprehensive consideration of historical policy and the economic development stage in a study area. This paper highlights the indirect role of village roads in soil erosion evolution.

The research on the grid size suitability is important to provide improvement in accuracies of gridded population distribution. It contributes to reveal the actual spatial distribution of population. However, currently little research has been done in this area. Many well-modeled gridded population dataset are basically built at a single grid scale. If the grid cell size is not appropriate, it will result in spatial information loss or data redundancy. Therefore, in order to capture the desired spatial variation of population within the area of interest, it is necessary to conduct research on grid size suitability. This study summarized three expressed levels to analyze grid size suitability, which include location expressed level, numeric information expressed level, and spatial relationship expressed level. This study elaborated the reasons for choosing the five indexes to explore expression suitability. These five indexes are consistency measure, shape index rate, standard deviation of population density, patches diversity index, and the average local variance. The suitable grid size was determined by constructing grid size-indicator value curves and suitable grid size scheme. Results revealed that the three expressed levels on 10m grid scale are satisfying. And the population distribution raster data with 10m grid size provide excellent accuracy without loss. The 10m grid size is recommended as the appropriate scale for generating a high-quality gridded population distribution in our study area. Based on this preliminary study, it indicates the five indexes are coordinated with each other and reasonable and effective to assess grid size suitability. We also suggest choosing these five indexes in three perspectives of expressed level to carry out the research on grid size suitability of gridded population distribution.

Accurate grid size suitability evaluations are necessary to enhance the spatialization quality of gridded population distributions. This paper proposes an improved average local variance (ALV) method to express discrepancies in population density and was validated in Anhui Province, China. A dataset consisting of 14 spatial scales, from 100 m to 900 m, and 1000 m to 5000 m, was processed by both the proposed and traditional ALV methods. Line graphs of two sets of ALV values and grid sizes were comparatively analyzed to evaluate the grid size suitability. The ALV trends calculated by the proposed method encompassed more accurate and useful features compared to the traditional method. The case study results showed that the 200 m grid size accurately expresses the population distribution characteristics of Anhui Province. The standard deviation (SD) index was adopted to validate these results; the proposed ALV method was proven valuable both in theory and practice for assessing grid size suitability. The method may be further improved by determining the essential laws of ALV values based on grid characteristics, and by enhancing the adaptability to various locations.

Ascertaining the relationships between sediment transport processes and vegetation cover is essential for watershed soil and water conservation. However, it is not easy to realize this target on a large scale. In this study, the location-weighted landscape contrast index (LCI) based on the “source-sink” theory of ecological processes was introduced to unravel the response of sediment yield to vegetation cover changes in the Poyang Lake drainage area (the largest freshwater lake in China). A modified location-weighted landscape contrast index (mLCI) was proposed to improve the accuracy and efficiency of the LCI. The average vegetation fraction of the study area significantly increased from 46.2% in Period I (1992–1994) to 76.5% in Period II (2004–2006) and then slightly decreased to 73.2% in Period III (2011–2013). From Period I to Period II, the area-specific sediment yield (ASY) sharply decreased by 55%. In Period II, the “source” vegetation patches were found further away from the water bodies, and were more likely to be located on gentler slopes than in Period I. From Period II to Period III, the ASY sharply increased by 83%. In Period III, “source” patches were found closer to the water bodies than in Period II, whereas the “sink” patches were found further away from the water bodies. The high statistical correlation between LCIs/mLCIs and ASY indicated a sensitive response of the sediment yield to vegetation cover changes that significantly altered the sediment transport processes in the study area. The ASY was better correlated with the mLCI than with the LCI. Three key harnessing sub-watersheds of the Ganjiang watershed were identified by calculating the mLCIs: Qingfengshan, Yuanhe, and Jinjiang. This study supported watershed ecological management in the Poyang Lake drainage area and provided a methodology reference for future sediment transport process studies.