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1.
Braz J Biol ; 83: e246436, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34495159

RESUMO

Application of different fertilizers to check the efficiency of expression of Bt (Bacillus thuringiensis) gene in one of the leading commercialized crops (cotton) against Lepidopteran species is of great concern. The expression of Cry protein level can be controlled by the improvement of nutrients levels. Therefore, the myth of response of Cry toxin to different combinations of NP fertilizers was explored in three Bt cotton cultivars. Combinations include three levels of nitrogen and three levels of phosphorus fertilizers. Immunostrips and Cry gene(s) specific primer based PCR (Polymerase Chain Reaction) analysis were used for the presence of Bt gene that unveiled the presence of Cry1Ac gene only. Further, the ELISA (enzyme-linked immunosorbent assay) kit was used to quantify the expression of Cry1Ac protein. Under various NP fertilizers rates, the level of toxin protein exhibited highly significant differences. The highest toxin level mean was found to be 2.3740 and 2.1732 µg/g under the treatment of N150P75 kg ha-1 combination while the lowest toxin level mean was found to be 0.9158 and 0.7641 µg/g at the N50P25 kg ha-1 level at 80 and 120 DAS (Days After Sowing), respectively. It was concluded from the research that the usage of NP fertilizers has a positive relation with the expression of Cry1Ac toxin in Bt cotton. We recommend using the N150P50 kg ha-1 level as the most economical and practicable fertilizer instead of the standard dose N100P50 kg ha-1 to get the desired level of Cry1Ac level for long lasting plant resistance (<1.5). The revised dose of fertilizer may help farmers to avoid the cross-resistance development in contradiction of insect pests.


Assuntos
Proteínas Hemolisinas , Mariposas , Animais , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/genética , Endotoxinas/genética , Fertilizantes , Proteínas Hemolisinas/genética , Resistência a Inseticidas , Larva , Nitrogênio , Fósforo , Plantas Geneticamente Modificadas/genética
2.
Nanoscale ; 13(31): 13506-13518, 2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34477755

RESUMO

Photodynamic therapy (PDT) has evolved as an essential method for infection control, but is confronted with challenges in terms of low oxygen supply, possible toxicity during light irradiation, and nonpersistent action. Herein, to address these limitations, black phosphorus (BP) is used as a photosensitizer and decorated with Pt nanoparticles and aminobenzyl-2-pyridone (APy) moieties to obtain BP@APy-Pt. The stability of BP is improved through the capture and occupation of lone-pair electrons after reductive deposition of Pt nanoparticles and covalent conjugation of APy. Pt nanoparticles on BP@APy-Pt catalyze the decomposition of endogenous H2O2 to produce oxygen for consecutive cycles with a stable production capacity. The light exposure to BP@APy-Pt generates significantly higher 1O2 levels than those of BP/light, and the generated 1O2 is partially captured by APy moieties. The captured 1O2 during 20 min of illumination shows a constant release for 24 h in the dark. The cycled storage and release feature eliminates the toxicity of 1O2 at high levels during illumination and leads to efficient destruction of S. aureus and P. aeruginosa. Compared to the healing rates after treatment with BP/light (57.6%), BP@Pt/light (64.8%), BP@APy/light (77.8%), and BP@APy-Pt (48.5%), the skin wounds with infected S. aureus are fully healed after BP@APy-Pt/light treatment. Blood vessels and hair follicles are regenerated to resemble those of normal skin. Thus, this study expands the PDT strategy through integration with oxygen generation, 1O2 storage, and persistent release to promote bactericidal efficacy and eliminate side effects.


Assuntos
Oxigênio , Fotoquimioterapia , Homicídio , Peróxido de Hidrogênio , Fósforo , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , Staphylococcus aureus
3.
Mater Sci Eng C Mater Biol Appl ; 128: 112309, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474860

RESUMO

Recently, black phosphorus (BP) has garnered great attention as one of newly emerging two-dimensional nanomaterials. Especially, the degraded platelets of BP in the physiological environment were shown to be nontoxic phosphate anions, which are a component of bone tissue and can be used for mineralization. Here, our study presents the potential of BP as biofunctional and biocompatible nanomaterials for the application to bone tissue engineering and regeneration. An ultrathin layer of BP nanodots (BPNDs) was created on a glass substrate by using a flow-enabled self-assembly process, which yielded a highly uniform deposition of BPNDs in a unique confined geometry. The BPND-coated substrates represented unprecedented favorable topographical microenvironments and supportive matrices suitable for the growth and survival of MC3T3-E1 preosteoblasts. The prepared substrates promoted the spontaneous osteodifferentiation of preosteoblasts, which had been confirmed by determining alkaline phosphatase activity and extracellular calcium deposition as early- and late-stage markers of osteogenic differentiation, respectively. Furthermore, the BPND-coated substrates upregulated the expression of some specific genes (i.e., RUNX2, OCN, OPN, and Vinculin) and proteins, which are closely related to osteogenesis. Conclusively, our BPND-coating strategy suggests that a biologically inert surface can be readily activated as a cell-favorable nanoplatform enabled with excellent biocompatibility and osteogenic ability.


Assuntos
Osteoblastos , Osteogênese , Diferenciação Celular , Fósforo , Engenharia Tecidual
4.
Anal Chem ; 93(36): 12400-12408, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34469691

RESUMO

The electrochemiluminescence (ECL) ratiometric assay is usually based on two different ECL luminophores, and the choice of two suitable luminophores and shared co-reactant makes its construction challenging. The single-emitter-based ECL ratio mode could overcome the limitation of two luminophores and simplify the construction process, so it is an ideal choice. In this work, CdTe quantum dots (CdTe QDs) were modulated using black phosphorus (BP) nanosheet to simultaneously emit the cathodic and anodic ECL signals, and H2O2 and tripropylamine (TPrA) served as the cathodic and anodic co-reactants, respectively. MicroRNA-126 (miRNA-126) was selected as the template target to exploit the application of BP-CdTe QDs in the single-emitter-based ECL ratio detection. Through the target recycling triggering rolling-circle amplification (RCA) reaction, a large amount of glucose oxidase (GOx)-modified single strand 1 was introduced. GOx catalyzed glucose to produce H2O2 in situ, which acted as a dual-role moderator to quench the anodic ECL emission with TPrA as the co-reactant while enhancing the cathodic emission, thereby realizing the ratiometric detection of miRNA-126 with a low detection limit of 29 aM (S/N = 3). The dual-ECL-emitting BP-CdTe QDs with TPrA-H2O2 as dual co-reactant provide a superior ECL ratio platform involving enzyme catalytic reaction, expanding the application of single-emitter-based ratio sensing in the diverse biological analysis.


Assuntos
Técnicas Biossensoriais , Compostos de Cádmio , MicroRNAs , Pontos Quânticos , Peróxido de Hidrogênio , Fósforo , Telúrio
5.
J Agric Food Chem ; 69(36): 10688-10699, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34472353

RESUMO

Phosphorus (P) is an essential nutrient; however, potential health impacts of high dietary levels of added soluble, highly bioavailable P salts especially are a concern. P sources with lower bioavailability are considered safer. Yet, speciation of different P sources to assess diets' risk to health is challenging. This investigation tested the value of in vitro water extraction and digestion assays to predict in vivo P apparent bioavailability/digestibility in feline diets. Thirty wet (n = 18) and dry (n = 12) format experimental and commercial cat foods were analyzed for nutrient content. Triplicate samples were subjected to in vitro water extraction, single-phase acidic (gastric; G) digestion, and dual-phase gastric and small intestinal (G-SI) digestion assays. Soluble and insoluble P were determined in the supernatant and pellet, respectively. A subset of the diets (seven wet, nine dry diets) was fed to healthy, adult cats (n = 7-24) to determine in vivo apparent P digestibility. Information on the soluble P salt sources and their contribution to total dietary P was available for some diets. Associations between data from the different in vitro assays and in vivo digestibility trials and the influence of different diet parameters were obtained using Pearson correlation and linear regression modeling. The % soluble P obtained from G-SI digestion assay correlated well with in vivo apparent P digestibility for wet (Pearson coefficient 0.926, p = 0.003), but not for dry diets (Pearson coefficient -0.074, p = 0.849). In contrast, the % soluble P determined by water extraction correlated well with the % soluble P salt contribution to total P for dry (Pearson coefficient 0.901, p < 0.001), but not for wet diets (Pearson coefficient -0.407, p = 0.365). Thus, 20 min water extraction can be used to predict soluble P salt content in dry diets; however, differing Ca:P ratios and water solubility of the P sources may affect the outcome and false-positive results can occur. The G-SI digestion assay employed can also be used to predict in vivo P digestibility. However, again, diet format, Ca:P ratios in diets, and possibly other factors can impact the results. Thus, data from in vitro assays to assess P sources and bioavailability need to be interpreted with care.


Assuntos
Digestão , Fósforo na Dieta , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Gatos , Dieta/veterinária , Nutrientes , Fósforo
6.
Sci Total Environ ; 792: 148550, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465039

RESUMO

Biochar and engineered biochar have been used for phosphorous recovery from wastewater, but the resulted phosphorous-laden (P-laden) biochar needs further disposal. In this study, the feasibility of reusing P-laden biochar for Pb immobilization as well as the underlying mechanism was explored. Three types of engineered biochar, i.e., Ca modified biochar, Mg modified biochar, and Fe modified biochar, were selected to sorb P and then the exhausted biochar was further used for Pb sorption. Results showed that Mg and Ca modified biochar exhibited considerable Pb sorption capacity after P sorption with the maximum value of 3.36-4.03 mmol/g and 5.49-6.58 mmol/g, respectively, while P-laden Fe modified biochar failed to sorb Pb due to its acidic pH. The removal of Pb by P-laden Mg modified biochar involved more precipitation including PbHPO4, Pb5(PO4)3(OH), and Pb3(CO3)2(OH)2 because of its higher P sorption capacity and more -OH group on the surface. Cation exchange with CaCO3 to form PbCO3 was the main mechanism for Pb removal by P-laden Ca modified biochar despite the formation of Pb5(PO4)3(OH) precipitate. Our results demonstrate that waste P-laden biochar can be further used for the effective removal of Pb, which provides a potential approach for waste adsorbent disposal.


Assuntos
Chumbo , Fósforo , Adsorção , Carvão Vegetal , Cinética
7.
Sci Total Environ ; 792: 148353, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465044

RESUMO

Eutrophication in coastal water has compromised ecosystem services. Identification of phosphorus (P) sources and their load contributions are required for the development of effective nutrient management plans. In this research, multi-isotope proxies were applied to track P sources and evaluate their relative contributions in Love Creek, a coastal estuary in Delaware. The isotope values of carbon (ca. -22‰), nitrogen (ca.+6‰), and phosphate oxygen (ca.+18‰) of agricultural soils under different agricultural practices are generally similar even though their concentrations are distinctly different from forest soils (δ13C: ca. -27‰; δ13N: ca.+2‰; δ18OP: ca.+22‰). Comparison of these parameters among potential land sources (agricultural soils, forest soils, septic wastes, and plant debris) and sink (colloids in water) revealed that the plant debris and soils from forest sources are likely dominant sources of P in freshwater sites. The contribution of terrestrial P sources gradually decreased along the salinity gradient and agricultural soil sources gradually dominanted in the saline water portion of the creek. The variations of P loads due to weather-related discharge, changing land use and activities, and seasons were high and reflected the limitation of accurate estimation of sources. Overall, these results provide improved insights into potential sources and biogeochemical processes in the estuary, which are expected to be useful for water quality monitoring programs.


Assuntos
Estuários , Fósforo , Ecossistema , Monitoramento Ambiental , Isótopos de Nitrogênio/análise , Fósforo/análise , Salinidade
8.
Water Res ; 203: 117511, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34375932

RESUMO

Efficient and sustainable removal of phosphate ions from an aqueous solution is of great challenge. Herein we demonstrated a greener route for phosphate recovery through struvite formation by using bacterial siderophore. This method was efficient for removal of phosphate as low as 1.3 mM with 99% recovery efficiency. The siderophore produced by Pseudomonas taiwanensis R-12-2 act as template for the nucleation of struvite crystals and was found sustainable for recycling the phosphorous efficiently after twenty cycles. The formation of struvite crystals is driven by surrounding pH (9.0) and presence of Mg2+ and NH4+ ions along with PO43- and siderophore which was further validated by computational studies. The morphology of struvite was characterized by scanning electron microscopy, followed by elemental analysis. Furthermore, our results revealed that the siderophore plays an important role in struvite biomineralization. We have successfully demonstrated the phosphate sequestration by using industrial waste samples, as possible application for environmental sustainability and phosphate conservation. For the first time electrochemical super-capacitance performance of the struvite was studied. The specific capacitance value for the struvite was found to be 320 F g-1 at 1.87 A g-1 and retained 92 % capacitance after 250 cycles. The study revealed the potential implications of siderophore for the phosphate recycling and the new mechanism for biomineralization by sequestering into struvite.


Assuntos
Fosfatos , Sideróforos , Magnésio , Fósforo , Pseudomonas , Estruvita , Águas Residuárias
9.
Bioresour Technol ; 340: 125696, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34385126

RESUMO

To reduce the eutrophication caused by nitrogen and phosphorus in water, invasive plant Eupatorium adenophorum was used to prepare biochar under different pyrolysis temperatures for the co-adsorption of nitrogen and phosphorus. The influencing factors of the co-adsorption of ammonium and phosphate onto EBC and its adsorption mechanism were systematically studied. The results show that Eupatorium adenophorum biochar (EBC) has rich functional groups and high specific surface area. Low pyrolysis temperature (300 °C) and alkaline conditions are beneficial for the co-adsorption. The adsorption of ammonium and phosphate by EBC is more in line with the pseudo-second-order kinetics and Langmuir-Freundlich model (Qmax is 2.32 mg P/g and 1.909 mg N/g). Site energy analysis further confirms that electrostatic attraction is the main mechanism. This study shows that EBC could be used as a low-cost and effective adsorbent to simultaneously remove ammonium and phosphate from water, providing a method for resource utilization of invasive plants.


Assuntos
Ageratina , Poluentes Químicos da Água , Adsorção , Carvão Vegetal , Cinética , Nitrogênio , Fósforo , Água , Poluentes Químicos da Água/análise
10.
Water Res ; 203: 117529, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34388499

RESUMO

To date, eutrophication becomes a great concern of vulnerable aquatic systems. Dissolved organic phosphorus (DOP) discharged from wastewater treatment plant (WWTP) holds a large source of phosphorus in receiving water. However, due to the complexity of DOP, their variation and fate in WWTP remain unknown at the molecular level, and are always overlooked. Here, the variation of DOP in a WWTP was uncovered via Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Results show that 95% of DOP in the influent could be removed by the secondary biological treatment processes. The removed DOP species were mainly lipids with the molecular characteristics of low oxygen content, low unsaturation and low aromaticity. Meanwhile, during biological treatments, some new DOP species, especially lignin/carboxylic rich alicyclic molecules (CRAM) that possessed high oxygen content, high unsaturation and high aromaticity, were produced and released into the secondary effluent. In the subsequent tertiary treatment, coagulation by aluminum salt tended to remove high molecular weight and high oxygen content DOP species in the secondary effluent, which was complementary to the biological treatment. However, the sand filter usually retained microorganisms, which would result in the generation of new DOP species in this process. During the final ultraviolet disinfection process, DOP was effectively mineralized to phosphate, especially the species with high molecular weight and highly unsaturated aromatic DOP species (e.g., lignin/CRAM and tannin), which had higher UV absorbance. The revealed variation of DOP in WWTP is beneficial to optimize the treatment processes to enhance the removal of DOP.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Desinfecção , Espectrometria de Massas , Fósforo , Poluentes Químicos da Água/análise
11.
Biomater Sci ; 9(18): 6108-6115, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34369491

RESUMO

Nanomedicines have been widely used in the effective delivery of chemotherapeutic drugs due to their advantages such as increasing the half-life of drugs, selectively targeting tumor tissues, and thus reducing systemic toxicity. However, the low drug entrapment rate and the difficulty of real-controlled release at tumor sites hinder their further clinical translations. Here we have developed biodegradable polyionic micelles (PD-M) to facilitate black phosphorus (BP) encapsulation (PD-M@BP) for improved drug loading. With the introduction of BP, PTX-loaded PD-M@BP (PD-M@BP/PTX) with sizes of 124-162 nm exhibited superior encapsulation efficiency over 94% and excellent colloidal stability. Meanwhile, PD-M well protected BP from fast degradation to show the good photothermal performance under near-infrared (NIR) irradiation, thus achieving the remotely controlled fast PTX release due to micelle core melting and dissociation, accompanied by the synergistic photothermal tumor therapy. The in vivo results demonstrated that the PD-M@BP/PTX nanosystem not only realized significant inhibition of multi-drug resistant (MDR) cervical tumors (HeLa/PTXR tumor) by remote NIR-regulation, but also reduced the potential damage of chemotherapeutic drugs to the whole body, rendering these hybrid nanosystems as great tools to treat MDR tumors synergistically.


Assuntos
Micelas , Neoplasias , Preparações de Ação Retardada , Humanos , Nanomedicina , Fósforo
12.
Int J Mol Sci ; 22(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34445391

RESUMO

The NIGT1/HRS1/HHO transcription factor (TF) family is a new subfamily of the G2-like TF family in the GARP superfamily and contains two conserved domains: the Myb-DNA binding domain and the hydrophobic and globular domain. Some studies showed that NIGT1/HRS1/HHO TFs are involved in coordinating the absorption and utilization of nitrogen and phosphorus. NIGT1/HRS1/HHO TFs also play an important role in plant growth and development and in the responses to abiotic stresses. This review focuses on recent advances in the structural characteristics of the NIGT1/HRS1/HHO TF family and discusses how the roles and functions of the NIGT1/HRS1/HHO TFs operate in terms of in plant growth, development, and stress responses.


Assuntos
Desenvolvimento Vegetal , Plantas/metabolismo , Fatores de Transcrição/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Nitrogênio/metabolismo , Fósforo/metabolismo , Proteínas de Plantas/metabolismo , Estresse Fisiológico
13.
Water Res ; 203: 117563, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34419918

RESUMO

Biological nitrogen (N) removal via the short-cut pathway (NH4+-N→NO2--N→N2) is economically attractive in wastewater treatment plants (WWTPs). However, biological phosphorus (P) removal processes remain a bottleneck in these systems due to the strong inhibitory effect of nitrite or its protonated form (HNO2, free nitrous acid - FNA) on polyphosphate accumulating organisms (PAOs). In this study, a novel combined nitrogen and phosphorus removal strategy was verified and achieved in a biological short-cut nitrogen removal system via side-stream sludge treatment with FNA, and the mechanisms impacting this process were investigated. The side-stream FNA treatment process applied here led to a significant reduction in the real sludge retention time (SRT) in the mainstream (approximately 2.7 days) based on the biocidal effect of FNA to the majority of the organisms. This work also found that around 40% of the P uptake activity was still maintained at a much higher FNA level of 38 µg N/L with potential PAOs, which highly broadened the current knowledge of PAOs community. An economic analysis revealed advantages of the proposed as compared to conventional biological nitrogen and phosphorus removal (13% savings in total cost), biological short-cut nitrogen removal (via FNA treatment) with chemical phosphorus precipitation (21% savings) and conventional biological nitrogen removal with chemical precipitation (27% savings). Overall, this study presents a novel and viable retrofit strategy in integrating biological short-cut nitrogen removal with EBPR for next generation WWTPs.


Assuntos
Fósforo , Esgotos , Reatores Biológicos , Nitrogênio , Rios
14.
Bioresour Technol ; 340: 125745, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34426241

RESUMO

In this study, the effects of P concentration and light/dark condition on the distribution of P in microalgae were tracked with Scenedesmus sp.393. Results showed that different culture conditions affected the accumulation capacity and transformation of P in intracellular polymeric substances (IPS), extracellular polymeric substances (EPS), and soluble microbial products (SMP). At low P concentration (0.70 mg P/L), inorganic phosphorus (IP) absorbed in EPS (19.40%) and organic phosphorus (OP) accumulated in IPS (70.98%) were mainly P forms in microalgae. High P concentration (>21.42 mg P/L) promoted the luxury uptake and accumulation of IP by IPS, and the conversion of IP to OP. However, the adsorption of IP by EPS was inhibited when exposed to high external P concentration. Continuous illumination promoted the microalgae growth, and dark condition stimulated the P accumulation in microalgae biomass. The results of this study could provide valuable information for P recovery with microalgae.


Assuntos
Microalgas , Scenedesmus , Biomassa , Matriz Extracelular de Substâncias Poliméricas , Nitrogênio , Fósforo
15.
Bioresour Technol ; 340: 125712, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34426242

RESUMO

Stable nitritation is the major challenge for short-cut nitrogen removal from municipal wastewater. This paper demonstrated a rapid achievement of partial nitrification (PN) in an enhanced biological phosphorus removal (EBPR) reactor treating domestic wastewater. Polyphosphate accumulating organisms (PAOs) were enriched operated at a short aerobic HRT (2.0 h) and SRT (10 d), with satisfactory phosphorus removal efficiency (95.9%). Both of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were elutriated simultaneously. Interestingly, AOB recovered much faster than NOB by a subsequent extension of aerobic HRT and SRT, resulting in a rapid development of PN within 15 days. Ammonia oxidation rates of AOB significantly increased by 44.2%, facilitating a high nitrite accumulation rate (NAR) of 95.8%. Genus Tetrasphaera, Halomonas, Paracoccus and Candidatus_Accumulibacter belonging to PAOs accounted for 4.6%. The proliferation of heterotrophs, typically as PAOs, maximized the microbial competition against NOB by favoring AOB activity and synergy with functional bacteria.


Assuntos
Nitrificação , Fósforo , Reatores Biológicos , Proliferação de Células , Interações Microbianas , Esgotos , Águas Residuárias
16.
Environ Pollut ; 287: 117619, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34426378

RESUMO

Enhanced release of phosphorus (P) from soils with snowmelt flooding poses a threat of eutrophication to waterbodies in cold climatic regions. Reductions in P losses with various soil amendments has been reported, however effectiveness of MgSO4 has not been studied under snowmelt flooding. This study examined (a) the P release enhancement with flooding in relation to initial soil P status and (b) the effectiveness of MgSO4 at two rates in reducing P release to floodwater under simulated snowmelt flooding. Intact soil monoliths were collected from eight agricultural fields from Southern Manitoba, Canada. Unamended and MgSO4 surface-amended monoliths (2.5 and 5.0 Mg ha-1) in triplicates were pre-incubated for 7 days, then flooded and incubated (4 °C) for 56 days. Pore water and floodwater samples collected at 7-day intervals were analyzed for dissolved reactive P (DRP), pH, Ca, Mg, Fe and Mn. Redox potential (Eh) was measured on each day of sampling. Representative soil samples collected from each field were analyzed for Olsen and Mehlich 3-P. Simulated snowmelt flooding enhanced the mobility of soil P with approximately 1.2-1.6 -fold increase in pore water DRP concentration from 0 to 21 days after flooding. Mehlich-3 P content showed a strong relationship with the pore water DRP concentrations suggesting its potential as a predictor of P loss risk during prolonged flooding. Surface application of MgSO4 reduced the P release to pore water and floodwater. The 2.5 Mg ha-1 rate was more effective than the higher rate with a 21-75% reduction in average pore water DRP, across soils. Soil monoliths amended with MgSO4 maintained a higher Eh, and had greater pore water Ca and Mg concentrations, which may have reduced redox-induced P release and favored re-precipitation of P with Ca and Mg, thus decreasing DRP concentrations in pore water and floodwater.


Assuntos
Poluentes do Solo , Solo , Inundações , Sulfato de Magnésio , Fósforo , Poluentes do Solo/análise , Água
17.
Environ Pollut ; 287: 117668, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34426390

RESUMO

Using Fe(II) salt as the precipitant in heterotrophic denitrification achieves improved TP removal, and enhancement in denitrification was often observed. This study aimed to obtain a better understanding of Fe(II)-enhanced denitrification with sufficient carbon source supply. Laboratory-scale experiments were conducted in SBRs with or without Fe(II) addition. Remarkably improved TP removal was experienced. TP removal efficiency in Fe(II) adding reactor was 85.8 ± 3.4%; whereas, that in the reactor without Fe(II) addition was 31.1 ± 2.8%. Besides improved TP removal, better TN removal efficiency (94.1 ± 1.1%) were recorded when Fe(II) was added, and that in the reactor without Fe(II) addition was 89 ± 0.8%. The specific denitrification rate were observed increase by 12.6% when Fe(II) was added. Further microbial analyses revealed increases in the abundances of typical denitrifiers (i.e. Niastella, Opitutus, Dechloromonas, Ignavibacterium, Anaeromyxobacter, Pedosphaera, and Myxococcus). Their associated denitrifying genes, narG, nirS, norB, and nosZ, were observed had 14.2%, 19.4%, 21.6%, and 9.9% elevation, respectively. Such enhancement in denitrification shall not be due to nitrate-dependent ferrous oxidation, which prevails in organic-deficient environments. In an environment with a continuous supply of Fe(II) and plenty of carbon sources, a cycle of denitrifying enzyme activity enhancement in the presence of Fe(II) facilitating nitrogen substrate utilization, stimulating denitrifier metabolism and growth, elevating denitrifying genes abundance, and increasing denitrifying enzymes expression were thought to be responsible for the Fe(II)-enhanced heterotrophic denitrification. Fe(II) salt is often a less expensive precipitant and has recently become attractive for TP removal in wastewater. The findings of this study solidify previous observation of enhancement of both TP and TN removal by adding Fe(II) in denitrification, and would be helpful for developing cost-effective pollutant removal processes.


Assuntos
Desnitrificação , Fósforo , Reatores Biológicos , Precipitação Química , Compostos Ferrosos , Nitratos , Nitrogênio , Águas Residuárias
18.
J Environ Manage ; 297: 113402, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34333312

RESUMO

Inefficient water management in rice paddy is responsible for a large quantity of water and nutrient loss, which causes tremendous economic and environmental costs. Yet, quantified data on the water and nutrient losses are limited. A study was conducted during 2018-2019 with an Aman (wet)-Boro (dry)-Aman (wet) rice rotation to evaluate the effect of water management on water and nutrient losses through different pathways. The treatments in 2018 Aman season were: (i) rainfed, (ii) I6D (irrigation after six days of ponded water disappearance), and (iii) I3D. In 2019, the Boro season had (i) I6D and (ii) I3D, and the Aman season had (i) rainfed, (ii) I9D, and (iii) I1D treatments. The water input and output from the studied lysimeters were measured daily, and samples from the leachates, ponded water, and topsoil were routinely analyzed for nutrient content. In both Aman seasons, the rainfed cultivation had lower percolation losses (38-44 % of total input) than other treatments (45-70 %). Evapotranspiration in the Boro season (5.4-5.9 mm/day) was higher than that in the Aman seasons (4.2-4.6 mm/day) because of the drier Boro season. Ammonium (NH4⁺-N) leached at 0.6-6.7 mg/L and nitrate (NO3⁻-N) 0.6-5.6 mg/L in these rice seasons. Phosphorus concentration ranged 0.04-0.37 mg/L in the leachates and 0.04-0.51 mg/L in the ponded water. The rainfed and I9D exerted higher nutrient leaching concentration in some events and less so for the I6D treatment than the I3D and I1D, possibly because of the better nitrification and preferential flow paths induced by the prolonged drying processes. However, the rainfed, I9D, and I6D had less leaching load than the I3D and I1D because the latter had larger percolation volume. For example, the I6D treatment in the Boro season reduced the N leaching load by 44 % and P load by 39 % compared with the I3D, and the I9D in 2019 Aman season had 42 and 13 % less N and P leaching load, respectively, than the I1D treatment. The findings will contribute to the effort of developing a sustainable and climate-resilient rice production system.


Assuntos
Oryza , Agricultura , Fertilizantes , Nitrogênio/análise , Nutrientes , Fósforo , Solo , Água
19.
Huan Jing Ke Xue ; 42(9): 4211-4221, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414719

RESUMO

Hanjiang River is the main water source and influence area of the Middle Route of the South to North Water Transfer Project. In recent years, the water quality and ecological environment in the middle and lower reaches of the Hanjiang River has become seriously degraded and water blooms occur frequently. Scientific identification of the temporal and spatial variations in water environment quality (and the main driving factors) has become an important management requirement for optimizing the upstream water transfer project. The temporal and spatial variations and influencing factors of water quality in the Hanjiang River basin were systematically analyzed, based on multi-source data and using the Daniel trend test, Mann Kendall test, K-means cluster analysis, dissimilarity analysis, and redundancy analysis. Results showed that: ① in recent years, the main stream of the Hanjiang River had generally good water quality, which was generally classified as class Ⅱ of GB 3838-2002, while the water quality of some sections in the middle and lower reaches was classified as class Ⅲ. However, the total phosphorus (TP) and total nitrogen (TN) load was relatively high, with 10 stations in the Hanjiang River basin showing averaged concentrations of 0.028-0.263 mg·L-1 and 0.630-1.852 mg·L-1, respectively, during 2014-2018. ② From 2004 to 2018, TP and TN at Zongguan station did not show significant variation, and other water quality indexes did not exhibit any regular patterns. The concentrations of TN, NH4+-N, and BOD5 in the dry season were higher than those in the wet season. In the wet season. the permanganate index showed different variation patterns, while TP concentration did not decrease significantly. ③ Different sections showed obvious differences in the variation of water quality indexes. However, the ten stations can be clustered into three categories: the upstream stations showed the best water quality, followed by the middle reaches, and the downstream stations showed the worst. The water quality at Xiaohe station improved significantly over the study period, which may be related to protection measures implemented in recent years, such as source control, emission reduction, and removal of aquaculture. ④ Water discharge and temperature were important factors affecting the water quality of the three regions in Hanjiang River. According to redundancy analysis, the contribution of discharge to water quality in the upstream and downstream areas was much larger, while the contribution of water temperature was greatest in the middle reaches of the river.


Assuntos
Monitoramento Ambiental , Qualidade da Água , Nitrogênio/análise , Fósforo/análise , Rios
20.
Huan Jing Ke Xue ; 42(9): 4275-4286, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414725

RESUMO

In this study, total phosphorus (TP) and the phosphorus (P) fractions in the water and surface sediments of the Baotou Nanhai wetland in China were determined using molybdenum blue/ascorbic acid spectrophotometry and continuous extraction methods. An APCS-MLR receptor model was combined with correlation analysis (CA) and principal component analysis (PCA) to identify and quantify the pollution sources. The results showed ① differences in the pollution level of phosphorus between the surface sediments and water. The contribution of dissolved inorganic phosphorus (DIP) to TP in the water (WTP) was the lowest, while the contribution of calcium-bound phosphorus (HCl-P) to TP in the surface sediments (STP) was the largest in the study area. The surface sediments of the Nanhai Lake (L area) and the wetland plant area (P area) exhibited high bioavailability and the potential for releasing phosphorus into the water, which could result in eutrophication and is therefore of concern. ② The APCS-MLR receptor model indicated that the main pollution sources of phosphorus were industrial wastewater and domestic sewage (29.07%), and pesticides and fertilizers (29.00%). In addition, the degradation of animal and plant residues (18.49%) also contributed to pollution in the study area.


Assuntos
Fósforo , Poluentes Químicos da Água , Monitoramento Ambiental , Sedimentos Geológicos , Fósforo/análise , Águas Residuárias , Poluentes Químicos da Água/análise , Áreas Alagadas
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