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1.
Chemosphere ; 238: 124682, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524619

RESUMO

Plant growth-promoting bacteria (PGPB) are considered a promising tool to improve biomass production and water remediation by the aquatic plant, duckweed; however, no effective methodology is available to utilize PGPB in large hydroponic systems. In this study, we proposed a two-step cultivation process, which comprised of a "colonization step" and a "mass cultivation step," and examined its efficacy in both bucket-scale and flask-scale cultivation experiments. We showed that in the outdoor bucket-scale experiments using three kinds of environmental water, plants cultured through the two-step cultivation method with the PGPB strain, Acinetobacter calcoaceticus P23, yielded 1.9 to 2.3 times more biomass than the control (without PGPB inoculation). The greater nitrogen and phosphorus removals compared to control were also attained, indicating that this strategy is useful for accelerating nutrient removal by duckweed. Flask-scale experiments using non-sterile pond water revealed that inoculation of strain P23 altered duckweed surface microbial community structures, and the beneficial effects of the inoculated strain P23 could last for 5-10 d. The loss of the duckweed growth-promoting effect was noticeable when the colonization of strain P23 decreased in the plant. These observations suggest that the stable colonization of the plant with PGPB is the key for maintaining the accelerated duckweed growth and nutrient removal in this cultivation method. Overall, our results suggest the possibility of an improved duckweed production using a two-step cultivation process with PGPB.


Assuntos
Acinetobacter calcoaceticus/metabolismo , Araceae/crescimento & desenvolvimento , Araceae/microbiologia , Hidroponia/métodos , Microbiota/fisiologia , Biomassa , Água Doce , Nitrogênio/análise , Nutrientes , Fósforo/análise , Desenvolvimento Vegetal , Purificação da Água/métodos
2.
Chemosphere ; 239: 124725, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499300

RESUMO

Use of wastewater is known to provide nutrients for crop plants, but its potential to improve phosphorus (P) availability in semi-arid regions is poorly understood. In this study, seasonal changes in soil P availability as well as associated phyiscochemical and biochemical indicators were investigated from the wastewater irrigated urban soils of Faisalabad, Pakistan. Soil sampling was carried out during summer and winter season from four wastewater irrigated sites of varied stream flow i.e. upstream wastewater (UWW), midstream wastewater (MWW), lowerstream wastewater (LWW) and downstream wastewater (DWW), and canal water irrigation (CWI) as a reference site. Across seasons, MWW site had significantly higher soil organic carbon (SOC), water extractable organic carbon (WEOC), microbial biomass carbon (MBC), microbial biomass phosphorus (MBP) as well as the availability of phosphorus i.e. NaHCO3-P and H2O-P compared to CWI site. In both sampling seasons, MWW site also recorded significantly higher soil enzyme activities compared to the rest of wastewater sites. Moreover, significantly higher total P and electrical conductivity (EC) of soil was noticed at DWW site across both summer and winter seasons. Biplot principle component analysis also indicated seasonally a stronger shift in soil total P and EC at DWW site. On the other hand, availability of P was closely related to soil active carbon pools at MWW site. However, buildup of soil salinity particularly at DWW site along with lower P availability and associated changes in other soil properties, call for careful assessment of wastewater use in these urban soils.


Assuntos
Irrigação Agrícola , Fósforo/análise , Solo/química , Águas Residuárias , Biomassa , Carbono/análise , Cidades , Paquistão , Fósforo/farmacocinética , Salinidade , Estações do Ano , Microbiologia do Solo , Águas Residuárias/química
3.
Chemosphere ; 239: 124709, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499302

RESUMO

The effect of organic fertilizers on soil phosphorus (P) availability is usually mainly associated with the rate and forms of P applied, while they also alter the soil physical-chemical properties, able to change P availability. We aimed to highlight the impact of pH and organic C modifications in soil on the inorganic P (Pi) sorption capacity and availability as compared to the effect of P accumulation after mineral or organic fertilizers. We conducted a 10-years-old field experiment on an andosol and compared fields that had been amended with mineral or organic (dairy slurry and manure compost) fertilizers against a non-fertilized control. Water and Olsen extractions and Pi sorption experiments were realized on soils sampled after 6 and 10 years of trial. We also realized an artificial and ex situ alkalization of the control soil to isolate the effect of pH on Pi sorption capacity. Organic fertilizer application increased total P, pH, and organic C in soil. Pi-Olsen increased mainly with soil total P (r2 adj = 0.79), while Pi-water increased jointly with soil total P and pH (r2 adj = 0.85). The Pi sorption capacity decreased with organic fertilizer application. Artificial and ex situ alkalization of the control soil showed that Pi sorption capacity decreased with increasing pH. Our study demonstrated that, beyond the P fertilization rate, the increase in organic C content and even more so in pH induced by a decade of organic fertilizer applications in soil decreased the Pi sorption capacity and consequently increased Pi-water in soil.


Assuntos
Fertilizantes , Fósforo/química , Solo/química , Adsorção , Carbono , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Esterco , Minerais , Fósforo/análise , Fósforo/farmacologia , Solo/normas
4.
Chemosphere ; 239: 124622, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31726532

RESUMO

Phosphorus (P), despite being an essential nutrient element for plants growth in agricultural ecosystem, the low utilization rate of soil P and the environmental problems caused by soil P losses are serious. Therefore, scoping knowledge of the possible sources and utilization extent of soil P by microorganisms is very helpful for better understanding of promoting P utilization for sustainable agriculture. Oxygen isotope of phosphate technology is an effective tool to trace the sources of P. In this study, P contents and oxygen isotope composition of inorganic phosphate (δ18OP) of different pools (H2O-P, NaHCO3-P, NaOH-P, and HCl-P) in typical agricultural soil from Northeast China and Central China were analyzed and quantified. The results showed that fertilizer and land use were important factors influencing the contents of H2O-Pt and NaHCO3-Pt and the soil TP contents from different types of soils were greatly affected by soil weathering degree. The δ18OP of different P pools indicated that the difference in utilization extent of different P fractions by microorganisms and the δ18OP values of different P fractions could be due to accumulation of multiple factors. The results will provide effective information for further study on sources and effective utilization of different P fractions in soil.


Assuntos
Monitoramento Ambiental/métodos , Fertilizantes/análise , Isótopos de Oxigênio/análise , Fosfatos/análise , Fósforo/análise , Solo/química , Agricultura/métodos , China , Ecossistema
5.
Sci Total Environ ; 701: 134660, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31704401

RESUMO

The biogeochemical cycles of plant nitrogen (N) and phosphorus (P) are interlinked by ecological processes, and the N and P cycles become uncoupled in response to global change experiments. However, the complex natural hydrothermal conditions in arid, semiarid and humid grassland ecosystems may have different effects on the availability of soil nutrients and moisture and may induce different balances between the N and P cycles. Here, we evaluated how the aridity index (AI) affects the balance between N and P of alpine grassland by the collected 115 sites along water and heat availability gradients on the Tibetan Plateau. We found that AI was negatively related to the variation in the coefficients of soil total dissolved N (TDN) and soil availability of P (SAP), and positive effects of AI, TDN and SAP on the coupling of plant N and P were detected. Thus, AI was positively correlated with soil nutrients and moisture, which may favor the co-uptake of soil nutrients by plants, resulting in a small variation in plant N and P in humid environments. Conversely, in arid environments with temporally variable soil nutrients, the plants tend to be more flexible in their N:P stoichiometry. Generally, our findings suggest that plant N and P could be more strongly coupled in humid conditions than in arid environments across alpine grasslands, with potential decoupling of the N biogeochemical cycle from P in an arid environment with an asynchronous dynamic of temperature and precipitation.


Assuntos
Monitoramento Ambiental , Pradaria , Nitrogênio/análise , Fósforo/análise , Microbiologia do Solo , Ecossistema , Temperatura Ambiente , Água
6.
Sci Total Environ ; 701: 134935, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31726415

RESUMO

Algal-bacterial system (ABS) used in treatment of high-strength ammonium wastewaters receives more and more attentions. In this paper, biochar-mediated absorption (BMA) and ABS were applied to recover nutrients from swine wastewater (SW) with high-strength ammonium, respectively. The results showed that the BMA could recover ammonium from the SW, which mitigated ammonia toxicity to the ABS. The bacterial community diversity containing four phyla of bacteria was identified for the first time during nutrients recovery from the SW by the ABS. Proteobacteria and Firmicutes were the two most abundant phyla. A novel scheme for nutrients recovery from the SW by the coupled BMA-ABS method was proposed and evaluated. Nutrients recovery was obviously improved by the coupled BMA-ABS method with biomass concentration of 1.97 g L-1, and a NH4+-N recovery efficiency of 96%, a total nitrogen recovery efficiency of 95%, a total phosphorus recovery efficiency of 96%, and a chemical oxygen demand recovery efficiency of 99%. The coupled BMA-ABS method could enhance nutrients recovery from the SW.


Assuntos
Carvão Vegetal , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/microbiologia , Nitrogênio/análise , Fósforo/análise
7.
J Environ Sci (China) ; 87: 260-271, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791499

RESUMO

An embedded reservoir that provides an efficient nutrient removal system protects drinking water. However, embedded reservoirs are rarely used in eutrophic shallow lakes because of their undetermined nutrient retention efficiency and unknown effects by the phytoplankton community. In this study, we aim to investigate the nutrient retention and algae succession in an embedded reservoir and adjacent wetland from April 2017 to September 2018 in the eastern part of Lake Taihu, China. More than 40% of total phosphorus (TP) and 45% of particulate phosphorous entering the reservoir were retained semi-annually, and the highest TP removal efficiency was achieved in the reservoir during autumn with an average value of 53.3% ±â€¯9.9%. The overall nitrogen retention efficiency (21.7% ±â€¯37.8%) was lower than that of TP (41.8% ±â€¯27.8%). Similar trends were obtained in the wetland area. An important pathway for phosphorus removal is through particulate matter retention. Our study revealed that nutrient retention mechanisms in the reservoir were primarily via macrophyte absorption, particulate substance sedimentation, and prolonged water residence time. Consequently, the phytoplankton biomass (Chl-a) in the reservoir decreased (from 48.0 to 25.2 µg/L) and water transparency improved, due to the decreased P level and transformation of the phytoplankton group into simple structures with good ecological status. Therefore, the combination of embedded reservoir and constructed wetland ecosystem can be used successfully to protect surface water. The results will be advantageous to groups seeking to preserve drinking water sources.


Assuntos
Água Potável , Monitoramento Ambiental , Áreas Alagadas , Biodegradação Ambiental , China , Ecossistema , Lagos/química , Nitrogênio/análise , Fósforo/análise , Fitoplâncton
8.
J Environ Sci (China) ; 87: 319-330, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791505

RESUMO

Silver nanoparticles (AgNPs) have been widely used in many fields, which raised concerns about potential threats to biological sewage treatment systems. In this study, the phosphorus removal performance, enzymatic activity and microbial population dynamics in constructed wetlands (CWs) were evaluated under a long-term exposure to AgNPs (0, 50, and 200 µg/L) for 450 days. Results have shown that AgNPs inhibited the phosphorus removal efficiency in a short-term exposure, whereas caused no obviously negative effects from a long-term perspective. Moreover, in the coexisting CW system of AgNPs and phosphorus, competition exhibited in the initial exposure phase, however, cooperation between them was observed in later phase. Enzymatic activity of acid-phosphatase at the moderate temperature (10-20°C) was visibly higher than that at the high temperature (20-30°C) and CWs with AgNPs addition had no appreciable differences compared with the control. High-throughput sequencing results indicated that the microbial richness, diversity and composition of CWs were distinctly affected with the extension of exposure time at different AgNPs levels. However, the phosphorus removal performance of CWs did not decline with the decrease of polyphosphate accumulating organisms (PAOs), which also confirmed that adsorption precipitation was the main way of phosphorus removal in CWs. The study suggested that AgNPs and phosphorus could be removed synergistically in the coexistence system. This work has some reference for evaluating the influences of AgNPs on the phosphorus removal and the interrelation between them in CWs.


Assuntos
Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Biodegradação Ambiental/efeitos dos fármacos , Fósforo/análise , Fósforo/metabolismo , Águas Residuárias , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade
9.
Huan Jing Ke Xue ; 41(1): 403-411, 2020 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854943

RESUMO

This study aims to understand the existence of stable soil organic carbon (C), nitrogen (N), and phosphorus (P) ratios in paddy soil. Based on a field soil survey database, the ecological stoichiometry of the C:N:P ratio of 110 subtropical paddy soil profiles and 587 genetic horizons were analyzed at a regional scale. Relevant analysis and redundancy analysis (RDA) are used to study the relationships between C:N:P ratios and soil-environmental factors (topography, parent materials, soil genetic horizons, soil groups, soil physical, and chemical properties). The results showed that the weighted averages of C:N, C:P, and N:P in paddy soils of subtropical regions were 12.6, 49, and 3.9, respectively, and C:N:P was 38:3.2:1. The C:N of paddy soil did not vary significantly with parent materials, soil groups, or genetic horizons. However, the C:P and N:P variations were significantly different, and the mean values of the two were much lower than global ratios (186 and 13.1) and average levels of C:P and N:P in Chinese soils (136 and 9.3). Although the C:N:P ratio in the paddy soil profile was relatively unstable, the topsoil C:N (14.2) was relatively stable due to the strong interaction between the topsoil and the environment. This reflects the close coupling of C and N in the topsoil of paddy fields under long-term anthrostagnic maturation. However, in the paddy soil profile, C:P and N:P were not stable, and there was no significant correlation between soil organic carbon (SOC) and total P content, total N, or total P content, which suggests that environmental changes may lead to soil C:N:P decoupling. It was found that topography, soil texture, iron oxide, and bulk density are all key soil-environmental factors that regulate the soil profile of rice paddy C:N:P.


Assuntos
Carbono/análise , Nitrogênio/análise , Oryza , Fósforo/análise , Solo/química , Microbiologia do Solo
10.
Food Chem ; 308: 125652, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31669949

RESUMO

Vegetables contain iron, zinc and phosphorus as complexes with phytates limiting their availability from a vegetarian diet, meaning non-haem iron deficiency anaemia and zinc deficiency immune malfunction are a risk. Although these elements have been analysed previously in biological fluids and cereal using LC-ICP-MS, there is no method suitable for analysing iron, zinc and phosphorus simultaneously in vegetables because of their complex matrix. In this study, we analysed iron, zinc and phosphorus in cabbage, broccoli, pepper, spinach, kale and rocket after a simulated gastrointestinal digestion using a newly optimised SEC-ICP-MS method. Ammonium nitrate, as the mobile phase, and a suitable rinsing regime, allowed good reproducibility and maintenance of the equipment. The method showed good reproducibility and can be easily adapted to other vegetables, as required.


Assuntos
Brassicaceae/química , Ferro/análise , Fósforo/análise , Verduras/química , Zinco/análise , Espectrometria de Massas , Reprodutibilidade dos Testes
11.
J Sci Food Agric ; 100(1): 277-286, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31523836

RESUMO

BACKGROUND: Biodiversity-based agricultural systems can improve production efficiency and sustainability, with fewer negative environmental impacts and lower use of external inputs. Mixed-cropping and rice-duck co-culture have been shown to produce ecological benefits and to have positive effects on paddy soil. However, the effects of a combination of mixed cropping with different rice cultivars and duck co-culture on soil nutrients availability and grain yields have not been evaluated. A paddy field experiment was carried out over two rice growing seasons to test these effects. RESULTS: Several combinations of rice cultivars, when integrated with duck co-culture, significantly increased the soil organic matter and total nitrogen contents during the rice growing seasons, as compared to mono-cropping systems. In mixed-cropping combined with duck co-culture (MCDC) systems, the soil alkali-hydrolyzable nitrogen content ranged from 4.33% to 17.86% higher than that in mono-cropping systems. Similar increases were found for soil available phosphorus (8.71-15.91%) and soil available potassium (8.65-39.43%) contents. Furthermore, MCDC produced higher grain yields and harvest indexes for both study seasons. CONCLUSION: The integration of MCDC systems had positive effects on soil nutrient contents of paddy fields, which could, in turn, lead to yield enhancements, as well as additional income for farmers in the form of organic duck meat. © 2019 Society of Chemical Industry.


Assuntos
Produção Agrícola/métodos , Patos/crescimento & desenvolvimento , Oryza/crescimento & desenvolvimento , Solo/química , Animais , China , Fertilizantes/análise , Nitrogênio/análise , Nitrogênio/metabolismo , Oryza/metabolismo , Fósforo/análise , Fósforo/metabolismo , Potássio/análise , Potássio/metabolismo , Estações do Ano
12.
J Sci Food Agric ; 100(2): 803-810, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31612503

RESUMO

BACKGROUND: New evidence has shown that arbuscular mycorrhizal (AM) fungi can contribute to the aluminum (Al3+ ) tolerance of host plants growing in acidic soils with phytotoxic levels of Al3+ . The aim of this study was to investigate the role of AM fungi isolated from naturally occurring Al3+ acidic soils in conferring host tolerance to Al3+ toxicity in three wheat cultivars differing in Al3+ sensitivity. The experiment was conducted in a soilless substrate (vermiculite/perlite, 2:1 v/v) using two Al3+ -tolerant wheat genotypes and one Al3+ -sensitive wheat genotype. The wheat was colonized with a consortium of AM fungi isolated from an Andisol, with or without Al3+ at a concentration of 200 µmol L-1 . RESULTS: The response of wheat to Al3+ in the medium was dependent on both the plant genotype and AM colonization. The benefits of the AM fungi to the wheat cultivars included an increased P concentration and relatively low Al3+ accumulation in the plants. This was achieved through two mechanisms. First, the metal-chelating capacity of the AM fungi was clear in two of the cultivars ('Tukan' and 'Porfiado'), in which the enhanced extraradical mycelium development was able to retain Al3+ in the glomalin and hyphae. Second, the increased AM-induced acid phosphatase activity in the rhizosphere of the other cultivar ('Atlas 66') increased host nutrition possibly by hyphae-mediated nutrient uptake and glomalin-related soil protein. CONCLUSION: The results suggest that the role of AM fungi in cultivar-specific Al3+ detoxification can be achieved by increased extraradical mycelial filters and enhanced bioavailability of P in the host rhizosphere. © 2019 Society of Chemical Industry.


Assuntos
Alumínio/metabolismo , Micorrizas/metabolismo , Fósforo/metabolismo , Poluentes do Solo/metabolismo , Triticum/microbiologia , Alumínio/análise , Alumínio/toxicidade , Hifas/crescimento & desenvolvimento , Hifas/metabolismo , Micélio/crescimento & desenvolvimento , Micélio/metabolismo , Micorrizas/crescimento & desenvolvimento , Fósforo/análise , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Triticum/crescimento & desenvolvimento , Triticum/metabolismo
13.
J Environ Sci (China) ; 86: 164-174, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31787181

RESUMO

This study reports the feasibility of using municipal wastewater biosolids as an alternative carbon source for biological phosphorus removal. The biosolids were treated by a low-temperature, thermal alkaline hydrolysis process patented by Lystek International Inc. (Cambridge, ON, Canada) to produce short-chain volatile fatty acids and other readily biodegradable organics. Two sequencing batch reactors (SBRs) were operated with synthetic volatile fatty acids (SynVFA) and readily biodegradable organics produced from the alkaline hydrolysis of municipal wastewater biosolids (Lystek) as the carbon source, respectively. Municipal wastewaters with different strengths and COD:N:P ratios were tested in the study. The reactors' performances were compared with respect to nitrogen and phosphorus removal. It was observed that phosphorus removal efficiencies were between 98%-99% and 90%-97% and nitrogen removal efficiencies were 78%-81%, and 67% for the SynVFA and Lystek, respectively. However, the kinetics for phosphorus release and uptake during the anaerobic and aerobic stages with Lystek were observed to be significantly lower than SynVFA due to the presence of higher order VFAs (C4 and above) and other fermentable organics in the Lystek.


Assuntos
Biodegradação Ambiental , Fósforo/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Reatores Biológicos , Canadá , Ácidos Graxos Voláteis , Fermentação , Hidrólise , Nitrogênio , Fósforo/análise , Esgotos , Águas Residuárias , Poluentes Químicos da Água/análise
14.
J Environ Sci (China) ; 86: 38-49, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31787189

RESUMO

Three fractions of alkaline phosphatase activity (APA), including phytoplankton APA (phyto-APA), bacterial APA (bact-APA), and free-APA, were examined in the sea surface microlayer (SML) and the subsurface water (SSW) from Daya Bay, Guishan Island, and Guanghai Bay of southern China. Relationships between APA and environmental parameters were analyzed. The growth of phytoplankton was significantly limited by dissolved inorganic phosphorus (DIP) in the three sea areas, especially in Daya Bay. Total-APA ranged between 1.41 and 35.26 nmol/L/hr, and the highest value was found in Daya Bay. The increased APA in Daya Bay was the result of the increase of phytoplankton biomass and the response of phytoplankton to P limitation. Phyto-APA was the main contributor in Daya Bay, while phyto- and free-APA co-dominated in Guishan Island and Guanghai Bay. Bact-, phyto-, and total-APA showed a significant inverse power function relationship with DIP, and 0.2 µmol/L was the threshold for DIP on particulates and total-APA. Pearson correlation analysis suggested that DIP limitation together with high N levels enhanced APA. High water temperature and freshwater input accelerated APA as well. Principal component analysis clearly separated samples from the three sea areas, as well as from the SML and the SSW, which indicated the differences in environmental parameters and APA levels. Our results highlight the influence of phosphorus limitation and environmental parameters on APA.


Assuntos
Fosfatase Alcalina/análise , Monitoramento Ambiental , Fósforo/análise , Fitoplâncton/crescimento & desenvolvimento , Biomassa , China
15.
World J Microbiol Biotechnol ; 36(1): 8, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31858273

RESUMO

The application of chemical fertilizers to enhance crop production is a major concern due to associated environmental pollution and health hazards. Hence, there is an urgent need to develop an eco-friendly solution to improve crop production and promote sustainable agriculture simultaneously. Stevia rebaudiana is an important medicinal crop being substitute for sugar, superior flavor outline, extensive medicinal properties, and also of agronomic interest. In the present study, bacterium STJP isolated from the rhizospheric soil of S. rebaudiana and identified as Bacillus safensis on the basis of 16S rRNA gene sequencing, showed good amount of zinc (4.4 mg/L) and potassium (5.4 mg/L) solubilization. Paneer-whey (a dairy waste) based bioformulation (P-WBF) was developed utilizing isolate B. safensis STJP (accession number NAIMCC TB-2833) and inspected for the quality and ability to enhance the growth, nutrients uptake, and stevioside content in S. rebaudiana. The application of P-WBF displayed a significantly higher concentration (153.12%) of stevioside in S. rebaudiana as compared to control. P-WBF treated Stevia plants showed significantly higher fresh and dry weight as well (as compared to control). Further, enhancement of phosphorous, nitrogen, potassium, and zinc uptake in plant tissue was also recorded by application of P-WBF. This study suggests the use of P-WBF based biofertilizer using B. safensis STJP to increase stevioside content in Stevia plant by a nutrient(s) linked mechanism. This novel approach can also be beneficial for utilization of a dairy waste in preparation of bioformulation and, for enhancement of crop yield by an ecofriendly manner leading to sustainable agriculture.


Assuntos
Bacillus/fisiologia , Diterpenos de Caurano/química , Fertilizantes/análise , Glucosídeos/química , Nutrientes/química , Desenvolvimento Vegetal , Stevia/crescimento & desenvolvimento , Agricultura , Bacillus/genética , Nitrogênio/análise , Fósforo/análise , RNA Ribossômico 16S/genética
16.
Huan Jing Ke Xue ; 40(6): 2904-2911, 2019 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854685

RESUMO

With the aim of studying the effects of different vegetation zones on soil aggregate stability and its stoichiometric characteristics, the soils under Robinia pseudoacacia plantations located within different vegetation zones on the Loess Plateau were selected as the research object. Indicators including the content, stoichiometry, and stability of different aggregate fractions were analyzed. The results showed that the content of >2 mm and 0.25-2 mm, the mean diameter (EMWD), and the geometric mean diameter (EGMD) of aggregate fractions were in the order of forest zone > forest-steppe zone > grassland zone. However, the stability proxies of aggregate fractions across the three vegetation zones indicated that the content and erodibility (K factor) of 0.053-0.25 mm exhibited an opposite trend. The overall trend of the soil organic carbon and total nitrogen of aggregate fractions among the three vegetation zones was that the forest zone significantly overtopped the forest-steppe zone and grassland zone, while the content of total phosphorus showed no significant differences among the three vegetation zones. Additionally, the content of soil organic carbon and total nitrogen of < 0.053 mm and 0.25-2 mm was the highest among the different fractions in the grassland zone, while that of 0.053-0.25 mm and 0.25-2 mm was the highest in the forest-steppe zone. In contrast, there were no significant differences in the content of organic carbon and total nitrogen in the forest zone among the different aggregate fractions. The total phosphorus content topped in < 0.053 mm fractions in the grassland zone and the forest-steppe zone, while that in the forest zone had no significant differences among the different aggregate fractions. Besides, the C:N ratios of < 0.053 mm and 0.053-0.25 mm in the steppe zone and the forest-steppe zone were higher than that in the forest zone, while that of 0.25-2 mm and >2 mm had insignificant differences among the three vegetation zones. The C:P and N:P ratios of fractions in the forest zone were significantly higher than that in the forest-steppe zone and steppe zone. Overall, the stability and stoichiometry of soil aggregate fractions exhibited relatively significant differences among the three vegetation zones. Additionally, the stability, soil organic carbon, and total nitrogen content of aggregate fractions in the forest zone were generally higher than those in the forest-steppe zone and grassland zone.


Assuntos
Florestas , Robinia , Solo/química , Carbono/análise , China , Nitrogênio/análise , Fósforo/análise
17.
Huan Jing Ke Xue ; 40(7): 3099-3107, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854707

RESUMO

In order to explore the composition of epiphytic algae and its related environmental factors, 12 sampling sites in the natural reaches and the backwater reaches (including perennial backwater sections and fluctuating backwater sections) were investigated among tributaries of the Caotang River, the Meixi River, and the Daxi River in the Fengjie district of the Chongqing section of the Three Gorges Reservoir under different hydrological regimes (i.e., storage and non-storage periods). Results showed that 103 species of epilithic algae belonging to 45 genera and 4 families are found in the 3 tributaries. This included 67 species belonging to 34 genus in the natural sections and 82 species (64 species in perennial backwater sections and 41 species in fluctuating backwater sections) belonging to 34 genera in the backwater sections. During the storage period, the dominant species in the natural sections were Melosira varians, Cocconeis placentula, Diatoma vulgure, Gyrosigma scalproides, and Oscillatoria tenuis, while the dominant species in the backwater sections were M. varians, Cymbella affinis,D. vulgure, Eucapsis alpina, and M. granulata. During the non-storage period, the dominant species in the natural sections were M. varians, C. affinis, and C. placentula, whereas the dominant species in the backwater sections were O. princeps, O. rupicola,O. formosa, Synedra acus, Ulothrix sp., Merismopedia elegans, and O. tenuis. These results suggested that the compositions of dominant species showed significant differences during the non-storage period, while little difference was found during the storage period. In addition, the dominant species did not show a significant change in the natural sections, but a marked difference was observed in the backwater sections. Similar dominant species were observed in both perennial and fluctuating backwater sections during the non-storage period, but significantly different dominant species were found during the storage period. Redundancy analysis suggested that the composition of epilithic algae was influenced by different environmental factors, such as temperature, electrical conductivity, pH, total nitrogen, and total phosphorus. Indeed, changes in the cell densities of dominant algae at the different sites were mainly affected by temperature and the concentrations of nitrogen and phosphorus. These results suggest that the different hydrological regimes had an important role not only on the reservoir water environment, but also the dynamics of epilithic algal communities.


Assuntos
Cianobactérias/fisiologia , Monitoramento Ambiental , Rios , China , Nitrogênio/análise , Fósforo/análise , Estações do Ano
18.
Huan Jing Ke Xue ; 40(7): 3118-3125, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854709

RESUMO

Decomposition of wetland plants could release pollutants, which may affect the removal efficiency and effluent quality of constructed wetlands. The experimental decomposition test of Myriophyllum aquaticum was carried out for 60 d using nylon bags, and release characteristics of nitrogen and phosphorus during the decomposition process were studied. The results showed that the decomposition rate of M. aquaticum was fastest during the first 0-4 d, with a weight loss of 30%, while the degradation rate slowed gradually during the period 4-60 d, with weight loss of 31%. The fitting first-order kinetic decomposition rate constant was 0.0142 d-1, and the calculated time to degrade 50% of dry matter was 48.8 d. The water pH decreased rapidly from 7.60 to 5.63 during 0-4 d, stabilized during 4-32 d, and finally increased to 7.03 (which was close to the control sample without M. aquaticum). The dissolved oxygen concentration decreased rapidly from 6.30 mg·L-1 to 0.61 mg·L-1 during 0-4 d, and remained in an anaerobic state. The total nitrogen concentration in the water increased rapidly to 12.7 mg·L-1 within 2 h, gradually decreased to 5.80 mg·L-1 during 2 h-32 d, and then finally increased slightly. The phosphorus concentration increased rapidly to 18.4 mg·L-1 at the beginning of the experiment, and then gradually stabilized. The main forms of nitrogen and phosphorus released by M. aquaticum were organic nitrogen (accounting for 65.7%-94.7% of total nitrogen) and inorganic phosphorus (accounting for 61%-89% of total phosphorus), respectively. The total nitrogen content of M. aquaticum increased from 24.3 mg·g-1 to 60.5 mg·g-1 with increasing degradation time; the total phosphorus decreased initially from 6.09 mg·g-1 to 2.94 mg·g-1 and then remained constant. These trends may have been related to the fixation of nitrogen by attached microorganisms. Therefore, suitable harvesting and management strategies should be adopted for wetland plants to reduce secondary pollution.


Assuntos
Nitrogênio/análise , Fósforo/análise , Saxifragales , Áreas Alagadas , Poluentes Químicos da Água/análise
19.
Huan Jing Ke Xue ; 40(7): 3304-3312, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854732

RESUMO

Phosphorus is an essential life element, which can affect the activities and functions of denitrifiers. Both nirK and nirS genes can code nitrite reductase; however, it remains unclear whether nirK- and nirS-containing denitrifers respond differentially to changes in the availability of phosphorus in paddy soil. In this study, P-deficient paddy soil was used to grow rice plants. Three phosphorus levels established by applying P fertilizer at a rate of 0 mg·kg-1 (CK), 15 mg·kg-1 (P1), and 30 mg·kg-1(P2), respectively. The abundance and community structure of nirK- and nirS- containing denitrifers were determined using quantitative PCR and high-throughput sequencing techniques. Results indicated that nirK- and nirS-containing communities responded differentially to changes in the P levels. The nirS-containing communities are more sensitive to the changes in P in both rhizosphere and bulk soil samples. In addition, the abundance of nirS genes was 2-3 times higher in the P2 treatment than in the CK treatment. Furthermore, the nirS community structure is also clearly differed from the CK treatment. However, P addition only induced partial modification of the community structure and abundance of nirK-containing denitrifiers. Moreover, compared to the bulk soil with each phosphorus level, the nirS community structure in the rhizosphere soil changed significantly; however, only the P2 treatment induced significant increases in the abundance of the nirS gene. In contrast, no significant differences in the abundance and composition of nirK-containing denitrifers were detected between rhizosphere and bulk soils under different phosphorus levels. Collectively, application of phosphate fertilizer in P-deficient paddy soil could significantly increase the abundance of nirK- and nirS-containing denitrifiers, changing their community structures, with nirS-type showing a greater sensitivity than nirK-type denitrifiers. In comparison, the denitrifying communities in the rhizosphere were more sensitive to variable P levels than that in the bulk soil. Compared to bulk soils, rice growth shifted the community structure of nirS- and nirK-containing denitrifiers in rhizosphere soils at each level of P, but failed to induce significant changes in their abundance (except for P2) that could cause a significant increase in nirS abundance. These results could provide a theoretical basis for exploring the effects of fertilization on soil denitrification.


Assuntos
Bactérias/classificação , Desnitrificação , Fósforo/análise , Microbiologia do Solo , Solo/química , Genes Bacterianos , Nitrito Redutases/genética
20.
Huan Jing Ke Xue ; 40(7): 3313-3323, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854733

RESUMO

In order to explore the effect of land-use change on soil bacteria in wetland systems, the topsoil (0-20 cm) of a natural wetland (NW), paddy field (PF), and dry land (DL) were collected in the Huixian karst wetland. The α-diversity, species composition, and abundance of soil bacterial communities were analyzed using high-throughput sequencing. The effect of environmental factors on bacterial community structure was also examined. The results showed that the soil bacteria in the Huixian karst wetland can be divided into 49 phyla and 145 classes. The Shannon index of bacteria in the PF was significantly higher, and the Simpson index of bacteria in the NW is significantly lower, than in the other two land-use types. The dominant phyla (operational taxonomic units, OTUs>1%) in the NW were Proteobacteria (52.15%), Actinobacteria (15.16%), and Acidobacteria (8.80%); the dominant phyla in the PF were Proteobacteria (45.79%), Acidobacteria (17.20%), and Chloroflexi (11.75%); the dominant phyla in the DL were Proteus (51.42%), Acidobacteria (15.51%), and Chloroflexi (7.43%). The dominant classes (OTUs>1%) in the NW were α-Proteobacteria (17.98%), ß-Proteobacteria (13.72%), and Actinobacteria (13.13%); the dominant classes in the PF were Acidobacteria (14.35%), ß-Proteobacteria (13.37%), and δ-Proteobacteria (12.02%); the dominant classes in the DL were α-Proteobacteria (19.44%), Formobacteria (13.30%), and Acidobacteria (13.03%). Among the dominant OTUs (>0.3%), the dominant genera of in the NW were Sphingomonas (OTU2, 59), Micromonospora (OTU5, 24 and 50487), Gemmatimonas (OTU1), and Tenotrophomonas (OTU8); the dominant genera in the PF were Lysobacter (OTU4 and 115) and Aquabacterium (OTU33); the dominant genera in the DL were Sphingomonas (OTU85, 157 and 2916), Rhodanobacter (OTU19 and 52), and Penlobacterium (OTU60). A heatmap showed that there were significant differences in soil bacterial community structure among the three land-use types. Redundancy analysis showed that pH, soil organic carbon (SOC), total nitrogen (TN), alkali-hydrolyzable nitrogen (AN), exchangeable Mg2+, exchangeable Ca2+, soluble organic carbon (DOC), and available phosphorus (AP) were the main factors that affected the bacterial community structure in the Huixian karst wetland. These results indicate that changes in land-use types have significantly shaped the structure of soil bacterial communities in this area.


Assuntos
Agricultura , Bactérias/classificação , Oryza , Microbiologia do Solo , Áreas Alagadas , Cálcio/análise , Carbono/análise , China , Nitrogênio/análise , Fósforo/análise
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