作者机构:
[Guan, Chunyun; Zhang, Yin; Chen, Can; Huang, Huang; Xu, Ying] Hunan Agr Univ, Coll Agron, Changsha 410128, Peoples R China.;[Guan, Chunyun; Zhang, Yin; Chen, Can; Huang, Huang] Hunan Engn Res Ctr Rice Field Ecol Planting & Bree, Changsha 410128, Peoples R China.;[Li, Zhengyou] Fisheries Res Inst Guizhou Prov, Guiyang 550025, Peoples R China.;[Luo, Jun] Congjiang Agr & Rural Bur Guizhou Prov, Congjiang 557400, Peoples R China.;[Ren, Bo] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Peoples R China.
通讯机构:
[Huang Huang] C;College of Agronomy, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Hunan Engineering Research Center of Rice Field Ecological Planting and Breeding, Changsha 410128, China
关键词:
rice-fish-duck symbiosis system;globally important agricultural heritage system;value;technology;challenge;countermeasure
摘要:
Abstract: The Chinese rice–fish–duck symbiosis system is one of the globally important agricultural heritage systems, with a history of nearly a thousand years. It embodies the wisdom of the Chinese ancestors and has huge comprehensive value, which has extremely important references for the sustainable development of agriculture. The technological core for the rice–fish–duck symbiosis system lies in the selection of rice, fish, and duck varieties and the coupling of agricultural operation time. In the process of modern agriculture, many varieties with high comprehensive benefits have also been applied to the rice–fish–duck system, and the rice–fish–duck model has been further developed. What is worrying is that the transfer of rural labor, the promotion of modern agricultural technology, the low degree of marketization and industrialization, the weakening of cultural awareness, and the change in climate have posed huge threats and challenges to the traditional Chinese rice–fish–duck system. The protection and development of the system are urgently needed. Therefore, we recommend delimiting active protection areas, establishing scientific research bases, improving relevant systems, developing rural tourism markets, and innovating farming technology, which also provide guidance for protecting and developing other agricultural cultural heritages. Keywords: rice–fish–duck symbiosis system; globally important agricultural heritage system; value; technology; challenge; countermeasure
摘要:
In the current work, the effects of biochar, vermicompost, as well as their combined application on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soils contaminated with potentially toxic elements (PTEs) were investigated. In this regard, four treatments were performed; among them, treatment A served as a control without additive, treatment B with vermicompost (2%), treatment C with biochar (2%), and treatment D with biochar (2%) plus vermicompost (2%). In addition, the abundance and structure of the AOA and AOB amoA gene were measured using quantitative PCR and high-throughput sequencing. The relationships between the microbial community, physicochemical parameters, and CaCl2-extractable PTEs were analyzed using the Pearson correlation method. We found that adding biochar and vermicompost promoted the immobilization of PTEs and nitrogen biotransformation. The rational use of biochar and vermicompost is beneficial for the growth of bacterial and fungal communities in soils polluted by PTEs. AOA and AOB amoA genes were stimulated by biochar, vermicompost, and their combination, but their structure was hardly affected.
通讯机构:
[Qingru Zeng] D;Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha 410128, China
关键词:
heavy metal;hydrochar;Cd;HCl;sunflower;species
摘要:
Abstract: The removal of heavy metals is crucial to the utilization of contaminated biomass resources. In this study, we report an efficient process of hydrothermal conversion (HTC) of sunflower straw (Helianthus annuus L.) to remove heavy metals. The effect of different HTC temperatures and concentrations of HCl additives on heavy metal removal efficiency was investigated. The results revealed that increasing the temperature or concentration of HCl promoted the transfer of heavy metals from hydrochar to liquid products during HTC. The heavy metals removed to the liquid products included up to 99% of Zn and Cd, 94% of Cu, and 87% of Pb after hydrothermal conversion with a temperature of 200 °C and HCl 2%. The species of heavy metals in hydrochars converted from unstable to stable with an increase in temperature from 160 °C to 280 °C. The stable fractions of heavy metals in the acidic condition decreased as the acid concentration increased. This aligns well with the high transfer efficiency of heavy metals from the solid phase to the liquid phase under acidic conditions. The FTIR indicated that the carboxy and hydroxy groups decreased significantly as the temperature increased and the concentration of HCl increased, which promoted the degradation of sunflower straw. A scan electron microscope showed that the deepening of the destruction of the initial microstructure promotes the transfer of heavy metals from hydrochars to liquid phase products. This acid-assisted hydrothermal process is an efficient method to treat biomass containing heavy metals. Keywords: heavy metal; hydrochar; Cd; HCl; sunflower; species
通讯机构:
[Yongliang Han] C;College of Resources and Environmental, Hunan Agricultural University, Changsha 410128, China<&wdkj&>National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, Changsha 410128, China
关键词:
double cropping rice;fertilization depth;Yield;utilization efficiency of N and P;N and P losses
摘要:
(1) Background: the broadcast is an outdated fertilization method with a low fertilizer-utilization rate and environmental problems, which seriously restricts the development of agriculture. (2) Methods: Under a machine-transplanted rice with side-deep fertilization (MRSF) mode, five treatments were applied: 0 cm (D0), 5 cm (D5), 7.5 cm (D7.5), and 10 cm (D10), comprising four different depths of fertilization, and no fertilization (CK). The yield, the accumulation of N and P in the straw and in grains of rice, concentrations of N and P in the surface water, ammonia (NH3) volatilization, and soil nutrients were measured in rice fields. (3) Results: In rice yields, compared with the D0 treatment, only the D7.5 treatment significantly increased by 7.84% in late rice, while the other treatments showed no significant difference between early and late rice. The N- and P-use efficiency of D10 increased by 5.30-24.73% and 0.84-17.75%, respectively, compared with the D0-D7.5 treatments. In surface water, compared with the D0 treatment, D5, D7.5, and D10, the total N (TN), total P (TP) concentration, and NH3 volatilization decreased by 10.24-60.76%, 16.30-31.01%, and 34.78-86.08%, respectively; the D10 treatment had the best inhibition effect on the TN, TP concentration, and NH3 volatilization, which were 58.48-60.76%, 22.04-31.01%, and 77.21-86.08%, respectively. (4) Conclusions: The optimized depth for side-deep fertilization was 10 cm. We would like to emphasize the impact of the paddy on various deep fertilizations and provide an important reference for developing precise fertilization in rice fields in this area.
摘要:
Abstract: Long-term of excessive fertilization using nitrogen (N) chemical fertilizer caused the acidification of paddy soils. Presently, the impacts of soil acidification on physiological characteristics of diazotrophic cyanobacteria remain unknown. In order to elucidate this issue, the effects of paddy floodwater acidification on activities of respiration, photosynthetic oxygen evolution, and N2 fixation of a paddy diazotrophic cyanobacterium Aliinostoc sp. YYLX235 were investigated in this study. In addition, the origination and quenching of intracellular reactive oxygen species (ROS) were analyzed. The acidification of paddy floodwater decreased intracellular pH and interfered in energy flux from light-harvesting chlorophyll antenna to the reaction center of photosystem II (PS II). Activities of respiration, photosynthetic oxygen evolution, and N2 fixation were decreased by the acidification of paddy floodwater. Accompanied with an increase in ROS, the level of antioxidative system increased. Superoxide dismutase (SOD) and catalase (CAT) were the main enzymatic ROS scavengers in the cells of YYLX235; reduced glutathione (GSH) was the main non-enzymatic antioxidant. Antioxidants and oxidants in the cells of YYLX235 lost balance when the pH of paddy floodwater fell to 5.0 and 4.0, and lipid oxidative damage happened. The results presented in this study suggest that the acidification of paddy soil severely interfered in the photosynthesis of diazotrophic cyanobacteria and induced the production of ROS, which in turn resulted in oxidative damage on diazotrophic cyanobacteria and a decrease in cell vitality. Keywords: acidification; diazotrophic cyanobacteria; photosynthesis; reactive oxygen species; antioxidants
通讯机构:
[Xin Liu] C;[Yulin Liao] S;College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Soil and Fertilizer Institute of Hunan Province, Hunan Academy of Agricultural Sciences, Changsha 410125, China
摘要:
Abstract: In this study, we conducted field experiments to assess the effects of the combined application of Chinese milk vetch (Astragalus sinicus L., CMV) and red mud (RM) to remediate the cadmium-polluted acidic paddy soil. The results showed that the combined application increased the yield component index and improved the grain yields, compared with the control, RM1, RM2, and CMV treatments. However, the increased range of soil pH values in the CMV-RM1 and CMV-RM2 treatments was smaller than that of the RM1 and RM2 treatments at the different rice growth stages. The soil organic matter (SOM) contents of the RM-only treatments did not differ throughout the whole period, but were significantly different (p < 0.05) between CMV-RM2 and the control. Compared with the control, the combined application decreased the concentration of exchangeable Cd in the early rice soil. The combined application of CMV and RM substantially decreased the rice uptake of Cd. However, we found no significant difference (p < 0.05) between the CMV-RM1 and CMV-RM2 treatments. Therefore, compared with remediation with RM or CMV alone, we recommend the combined application of CMV and RM as an economical, highly effective, and replicable amendment for remediating acidic, Cd-polluted paddy soil. Considering the restorative effect and proper use of RM, we recommend CMV-RM1 treatment. Keywords: cadmium; contamination; red mud; Chinese milk vetch; rice; paddy soil
通讯机构:
[Chen, A.] C;[Li, F.] S;College of Resources and Environment, China;School of Information and Safety Engineering, China
关键词:
Cumulative frequency curve method;PM2.5 baseline;hierarchical management strategy;China;Air Quality
摘要:
Provincial PM2.5 pollution management in China is facing great challenges, which is necessary to formulate hierarchical management strategies according to the specific situation of each province to achieve environmental equity management. This work calculates and analyzes the baseline value of PM2.5 in 31 provinces in China from 2018 to 2019 using the cumulative frequency curve method. Results showed that 93% of the provinces have two inflection points in the cumulative frequency curve, indicating that human activities showed a significant impact on PM2.5. The obtained baselines were assuredly lower than the corresponding monitoring values, which represented upper limits of PM2.5 in a certain area under low human activities. According to the relative size of baseline values, monitoring values, and national standard values, the following three types of results were obtained. Category I was classified as the standard value > monitoring values > baseline value. Category II was classified as the monitoring values > baseline value > standard value. Category III is the monitoring values > standard value > baseline value. A more practical hierarchical management strategy is formulated according to the relationship between baseline, monitoring, and standard values. Category I keeps the current status while striving to bring PM2.5 emissions closer to the baseline value. Category II implements the ‘step-by-step’ measures of reducing to the baseline value and then to the standard val...
作者机构:
[Tian, Qingshan; Huang, Yunxiang] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Peoples R China.;[Wang, Peng] China Haohua North Chem, 19 Xiaoying Rd, Beijing 100101, Peoples R China.;[Zhang, Bo; Jiao, Wentao] Chinese Acad Sci, Res Ctr Ecoenvironm Sci, 18 Shuangqing Rd, Beijing 100085, Peoples R China.
通讯机构:
[Bo Zhang] R;[Yunxiang Huang] C;College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
摘要:
Abstract: Uranium and arsenic are two pollutants commonly found in groundwater near uranium mines. However, the reactivity of U(VI) and As(V) need to be carefully investigated to better understand their fate and transport in the environment. In this study, the reactivity of U(VI) and As(V) were studied under various pH, bicarbonate, and Ca2+ levels. In air-equilibrated systems, the reactivity of U(VI) and As(V) generally decreased with the increase in pH, as evidenced by the solubility of U(VI) and As(V) increasing along with the elevation of pH. At pH = 8, 44.70% and 37.81% of initially added U(VI) and As(V) remained soluble. The addition of 1 mM of bicarbonate increased the reactivity of U(VI) and As(V) at mild acidic to neutral pH; however, the presence of bicarbonate significantly increased the solubility of U(VI) at mild alkaline condition, as nearly all U(VI) remained soluble at pH values of 8 and 9. After the addition of Ca2+, the solubility of both U(VI) and As(V) decreased at mild acidic to neutral pH ranges; however, the addition of Ca2+ markedly increased the soluble percentages of U(VI) at neutral pH, in which the condition 97.81 ± 2.95% of U(VI) remained soluble. Comparatively, only 36.13 ± 4.98% and 1.69 ± 1.08% of U(VI) were soluble at the same pH in air-equilibrated and bicarbonate systems. Our study demonstrated that U(VI) and As(V) are less reactive at neutral to alkaline conditions. Furthermore, the addition of bicarbonate and Ca2+ can further reduce the reactivity of U(VI) and As(V) at neutral to alkaline conditions. The findings of this study contribute to a deeper understanding of the fate and transport of U(VI) and As(V) in groundwater and could aid in better designing of U(VI) and As(V) removal processes. Keywords: groundwater; heavy metal; precipitation; phreeqc; water chemistry
作者机构:
[Zhang, Wei; Wang, Kelin; Liu, Xiajiao; Xiao, Shuangshuang] Chinese Acad Sci, Inst Subtrop Agr, Key Lab Agroecol Proc Subtrop Reg, Changsha 410125, Peoples R China.;[Chen, Wurong; Xiao, Shuangshuang] Nanning Normal Univ, Guangxi Key Lab Earth Surface Proc & Intelligent, Nanning 530001, Peoples R China.;[Liu, Xiajiao] Univ Chinese Acad Sci, Beijing 100039, Peoples R China.;[Ye, Yingying] Hunan Agr Univ, Coll Resources & Environm, Changsha 410125, Peoples R China.
通讯机构:
[Kelin Wang] K;Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
摘要:
Abstract: Tillage leads to rapid loss of soil nitrogen (N) over a short period of time in karst areas. N leaching is the primary pathway of soil N loss and therefore is key to understanding the mechanisms of N loss induced by tillage. However, the factors affecting N leaching under tillage are not fully understood. Effects of tillage at various frequencies on leached N were examined in a one-year in situ simulation experiment using five tillage treatments: no tillage (T0), semiannual tillage (T1), and tillage every four months (T2), two months (T3), and monthly (T4). Concentration and amount of leached N had peaks in dry–rewetting months. Tillage significantly increased total amounts of leached N during the one-year experiment, and the largest amount of leached N was under tillage at the highest frequency. The primary form of N in leachate was NO3¯ (88.49–91.11%), followed by DON (7.80–9.87%), and then NH4+ with the lowest amount (1.09–2.10%). Tillage increased the amount of leached NO3¯ and DON, but had no significant effect on leached NH4+. Additionally, the amount of leached N had significantly negative correlations with 5–8 mm soil aggregate, NO3¯, DON, and sand content, and positive correlations with 2–5 and 0.25–2 mm. Soil 5–8 mm aggregate and DON were the main factors explaining the variation in leached N according to the RDA analysis. Tillage increased the breakdown of large aggregates, appearing to have increased the mineralization of organic matter, which resulted in increased N leaching. Our results emphasize the importance of reducing or eliminating physical disturbance indued by tillage and maintenance of large soil aggregates for decreasing N leachate in lime soil of karst regions. Keywords: karst ecosystem; human disturbance; nitrate; leachate; aggregate
作者机构:
[Long, Xiaojie; Tang, Hongjiu] Hunan Agr Univ, Coll Landscape Architecture & Art Design, Changsha, Peoples R China.;[Tang, Hongjiu] Sun Yat Sen Univ, Sch Geog & Planning, Guangzhou, Peoples R China.;[Liu, Zhaoyin] Hunan Agr Univ, Coll Resources & Environm, Changsha, Peoples R China.
摘要:
This study examines farmers' intentions towards pro-environmental behavior in a famous tourist village in China called Guanshan, whose ecological environment is polluted. By adopting the empirically validated norm activation model (NAM) of Schwartz and merging it with Vroom's expectancy theory, the current research aims to develop a refined framework for understanding the formation of and predicting changes in pro-environmental intention. Field surveys were conducted in Guanshan, which resulted in sample data consisting of 275 valid responses collected by the research team. We develop a refined model, including six latent variables and 24 observational items. The structural equation modeling results show that the final model enjoys a better predictive accuracy of pro-environmental intention than does the original NAM. The study also discovers that the motivational force of expectancy theory significantly influences pro-environmental intention, whose motivational force comes from the impact of valence and expectancy. The pro-environmental intentions of farmers are mainly affected by the environmental personal norm and by a certain degree of personal expectancy. The improvement of farmers' pro-environmental intention needs be promoted in two approaches: the cultivation of personal environmental protection norms and the guidance of producing a desired expectation for pro-environmental intention.
摘要:
In this study, the role of exogenous root exudates and microorganisms was investigated in the application of modified nanoscale zero-valent iron (nZVI) for the remediation of cadmium (Cd)-contaminated soil. In this experiment, citric acid (CA) was used to simulate root exudates, which were then added to water and soil to simulate the pore water and rhizosphere environment. In detail, the experiment in water demonstrated that low concentration of CA facilitated Cd removal by nZVI, while the high concentration achieved the opposite. Among them, CA can promote the adsorption of Cd not only by direct complexation with heavy metal ions, but also by indirect effect to promote the production of iron hydroxyl oxides which has excellent heavy metal adsorption properties. Additionally, the H(+) dissociated from CA posed a great influence on Cd removal. The situation in soil was similar to that in water, where low concentrations of CA contributed to the immobilization of Cd by nZVI, while high concentrations promoted the desorption of Cd and the generation of CA-Cd complexes which facilitated the uptake of Cd by plants. As the reaction progressed, the soil pH and cation exchange capacity (CEC) increased, while organic matter (OM) decreased. Meanwhile, the soil microbial community structure and diversity were investigated by high-throughput sequencing after incubation with CA and nZVI. It was found that a high concentration of CA was not conducive to the growth of microorganisms, while CMC had the effect of alleviating the biological toxicity of nZVI.
通讯机构:
[Li, Xiaoma] H;Hunan Agr Univ, Coll Landscape Architecture & Art Design, Inst Educ, Hunan Prov Key Lab Landscape Ecol & Planning & De, Changsha 410128, Peoples R China.
关键词:
spatiotemporal change;pseudo-invariant feature;relative normalization;urban expansion;urban heat island
摘要:
The Landsat land surface temperature (LST) product is widely used to understand the impact of urbanization on surface temperature changes. However, directly comparing multi-temporal Landsat LST is challenging, as the observed LST might be strongly affected by climatic factors. This study validated the utility of the pseudo-invariant feature-based linear regression model (PIF-LRM) in normalizing multi-temporal Landsat LST to highlight the urbanization impact on temperature changes, based on five Landsat LST images during 2000–2018 in Changsha, China. Results showed that LST of PIFs between the reference and the target images was highly correlated, indicating high applicability of the PIF-LRM to relatively normalize LST. The PIF-LRM effectively removed the temporal variation of LST caused by climate factors and highlighted the impacts of urbanization caused land use and land cover changes. The PIF-LRM normalized LST showed stronger correlations with the time series of normalized difference of vegetation index (NDVI) than the observed LST and the LST normalized by the commonly used mean method (subtracting LST by the average, respectively for each image). The PIF-LRM uncovered the spatially heterogeneous responses of LST to urban expansion. For example, LST decreased in the urban center (the already developed regions) and increased in the urbanizing regions. PIF-LRM is highly recommended to normalize multi-temporal Landsat LST to understand the impact of urbanization on surface temperature changes from a temporal point of view.
关键词:
composting;zeolite;biochar;microbial community structure;shaping factor
摘要:
Bacterial and fungal communities play significant roles in waste biodegradation and nutrient reservation during composting. Biochar and zeolite were widely reported to directly or indirectly promote microbial growth. Therefore, the effects of zeolite and biochar on the abundance and structure of bacterial and fungal communities and their shaping factors during the composting of agricultural waste were studied. Four treatments were carried out as follows: Run A as the control without any addition, Run B with zeolite (5%), Run C with biochar (5%), and Run D with zeolite (5%) and biochar (5%), respectively. The bacterial and fungal community structures were detected by high-throughput sequencing. Redundancy analysis was used for determining the relationship between community structure and physico-chemical parameters. The results indicated that the addition of biochar and zeolite changed the physico-chemical parameters (e.g., pile temperature, pH, total organic matter, ammonium, nitrate, and water-soluble carbon) during the composting process. Zeolite and biochar significantly changed the structure and diversity of bacterial and fungal populations. Moreover, the bacterial community rather than the fungal community was sensitive to the biochar and zeolite addition during the composting process. Community phylogenetic characteristics showed that Nocardiopsaceae, Bacillaceae, Leuconostocaceae, Phyllobacteriaceae, and Xanthomonadaceae were the predominant bacterial species at the family-level. Chaetomiaceae and Trichocomaceae were the two most dominant fungal species. The pH, total organic matter, and nitrate were the most important factors affecting the bacterial and fungal population changes during the composting process.
关键词:
land use change;runoff;climate change;SWAT model
摘要:
Quantitative assessment of the impact of land use and climate change on hydrological processes is of great importance to water resources planning and management. The main objective of this study was to quantitatively assess the response of runoff to land use and climate change in the Zhengshui River Basin of Southern China, a heavily used agricultural basin. The Soil and Water Assessment Tool (SWAT) was used to simulate the river runoff for the Zhengshui River Basin. Specifically, a soil database was constructed based on field work and laboratory experiments as input data for the SWAT model. Following SWAT calibration, simulated results were compared with observed runoff data for the period 2006 to 2013. The Nash-Sutcliffe Efficiency Coefficient (NSE) and the correlation coefficient (R-2) for the comparisons were greater than 0.80, indicating close agreement. The calibrated models were applied to simulate monthly runoff in 1990 and 2010 for four scenarios with different land use and climate conditions. Climate change played a dominant role affecting runoff of this basin, with climate change decreasing simulated runoff by -100.22% in 2010 compared to that of 1990, land use change increasing runoff in this basin by 0.20% and the combination of climate change and land use change decreasing runoff by 60.8m(3)/s. The decrease of forestland area and the corresponding increase of developed land and cultivated land area led to the small increase in runoff associated with land use change. The influence of precipitation on runoff was greater than temperature. The soil database used to model runoff with the SWAT model for the basin was constructed using a combination of field investigation and laboratory experiments, and simulations of runoff based on that new soil database more closely matched observations of runoff than simulations based on the generic Harmonized World Soil Database (HWSD). This study may provide an important reference to guide management decisions for this and similar watersheds.
摘要:
The development of novel and green photocatalysts have attracted considerable attentions due to their excellent performance for environmental remediation, especially for the degradation of persistent pollutants. In this work, the biochar-supported K-doped g-C3N4 composites with the high photocatalytic activity under visible light irradiation was prepared by the calcination-impregnation method. The crystal structure, apparent morphology and functional group composition of the as-prepared photocatalytic materials were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscope (FTIR). Moreover, the characterization of UV-Vis diffuse reflectance spectra (UV-Vis DRS) and photoluminescence technique (PL) verified the good optical properties of resultant samples. Naphthalene was selected as the representative compound to evaluate the photocatalytic performance of the prepared photocatalysts under visible light irradiation. The evaluation results showed that the biochar-supported K-doped g-C3N4 composites exhibited excellent photocatalytic activity (82.19%). Moreover, the photocatalytic degradation rate basically remained unchanged after five cycles, indicating the good stability of the prepared photocatalysts. In addition, a possible mechanism for the photodegradation process was proposed on the basis of the main intermediates detected by gas chromatography-mass spectrometer (GC-MS). This study may provide a promising approach for the polycyclic aromatic hydrocarbon degradation by waste utilization of agricultural biomass and increasing the photocatalytic performance of pure g-C3N4.