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1.
J Environ Sci (China) ; 99: 187-195, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183696

RESUMO

Periodically hydrologic alterations driven by seasonal change and water storage capacity management strongly modify physicochemical properties and chlorophyll-a (Chl-a) and their interactions in dam-induced lakes. However, the extent and magnitude of these changes still remain unclear. This study aimed to determine the effects of periodically hydrologic alterations on physicochemical variables and Chl-a in the dam-induced urban Hanfeng Lake, upstream of Three Gorges Reservoir. Shifts in Chl-a and 13 physicochemical variables were recorded monthly in the lake from January 2013 to December 2014. Chl-a was neither seasonal nor inter-annual differences while a few physical variables such as flow velocity (V) exhibited significantly seasonal variabilities, and chemical variables like total nitrogen (TN), nitrate-nitrogen (NO3-N), total phosphorus (TP), dissolved silica (DSi) were markedly inter-annual differences. Higher TN:TP (40:1) and lower NO3-N:DSi (0.8:1) relative to balanced stoichiometric ratios suggested changes in composition of phytoplankton communities and potentially increased proportion of diatom in Hanfeng Lake. Chl-a was predicable by combination of dissolved oxygen (DO), TN and DSi in dry season, and by V alone in wet season. During the whole study period, Chl-a was solely negatively correlated with TN:TP, indicating decline in N concentration and increase in P could therefore increase Chl-a. Our results highlight pronounced decoupling of linkages between Chl-a and physicochemical variables affected by periodically hydrologic alterations in dam-induced aquatic systems.


Assuntos
Eutrofização , Lagos , China , Clorofila/análise , Clorofila A , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise
2.
Food Chem ; 337: 127771, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777564

RESUMO

Faveleira (Cnidoscolus quercifolius) is an emerging Brazilian plant, with seeds rich in edible oil. This study investigates physicochemical properties, chemical composition, thermal and oxidative stability, in vitro and in vivo toxicity, antioxidant, antinociceptive and anti-inflammatory activities of faveleira seed oil. It was observed that the oil has low acidity, value of peroxide, chlorophyll, carotenoids, ß-carotene and high concentrations of unsaturated fatty acids. In addition to presenting thermal and oxidative stability and high total phenolic content, with vanillin, eugenol and quercetin were predominating. The oil showed no toxicity in vitro and in vivo, and presented antioxidant, anti-inflammatory and antinociceptive activities. These findings provide relevant and appropriate conditions for processing of faveleira seed oil as functional food.


Assuntos
Euphorbiaceae/metabolismo , Óleos Vegetais/química , Analgésicos/química , Analgésicos/farmacologia , Analgésicos/uso terapêutico , Animais , Antioxidantes/química , Brasil , Carotenoides/análise , Sobrevivência Celular/efeitos dos fármacos , Clorofila/análise , Euphorbiaceae/química , Ácidos Graxos/análise , Masculino , Camundongos , Dor/induzido quimicamente , Dor/prevenção & controle , Fenóis/análise , Óleos Vegetais/farmacologia , Óleos Vegetais/uso terapêutico , Células RAW 264.7 , Sementes/química , Sementes/metabolismo
3.
Nat Commun ; 11(1): 5364, 2020 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-33097697

RESUMO

Over the last ten years, satellite and geographically constrained in situ observations largely focused on the northern hemisphere have suggested that annual phytoplankton biomass cycles cannot be fully understood from environmental properties controlling phytoplankton division rates (e.g., nutrients and light), as they omit the role of ecological and environmental loss processes (e.g., grazing, viruses, sinking). Here, we use multi-year observations from a very large array of robotic drifting floats in the Southern Ocean to determine key factors governing phytoplankton biomass dynamics over the annual cycle. Our analysis reveals seasonal phytoplankton accumulation ('blooming') events occurring during periods of declining modeled division rates, an observation that highlights the importance of loss processes in dictating the evolution of the seasonal cycle in biomass. In the open Southern Ocean, the spring bloom magnitude is found to be greatest in areas with high dissolved iron concentrations, consistent with iron being a well-established primary limiting nutrient in this region. Under ice observations show that biomass starts increasing in early winter, well before sea ice begins to retreat. The average theoretical sensitivity of the Southern Ocean to potential changes in seasonal nutrient and light availability suggests that a 10% change in phytoplankton division rate may be associated with a 50% reduction in mean bloom magnitude and annual primary productivity, assuming simple changes in the seasonal magnitude of phytoplankton division rates. Overall, our results highlight the importance of quantifying and accounting for both division and loss processes when modeling future changes in phytoplankton biomass cycles.


Assuntos
Biomassa , Fitoplâncton/crescimento & desenvolvimento , Estações do Ano , Água do Mar/microbiologia , Biodiversidade , Carbono/análise , Clorofila/análise , Clima , Ecologia , Camada de Gelo , Luz , Biologia Marinha , Meteorologia , Nutrientes , Oceanos e Mares , Dinâmica Populacional , Microbiologia da Água
4.
J Oleo Sci ; 69(11): 1517-1528, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33055437

RESUMO

Sargassum brown seaweed is known to have many health benefits and therapeutic effects. Preliminary chemical characterization of this seaweed is important as a bioprospecting strategy for seaweed industry development. This study aimed to evaluate chemical composition differences, both water and lipidsoluble component, of Sargassum cristaefolium from four different coastal areas in Indonesia, namely Pari Island/PI, Awur Bay/AB, Ujung Genteng Beach/UGB, and Sayang Heulang Beach/SHB. Principal component analysis (PCA) on water-soluble component made samples from different origins to be clearly distinguished (variance: 80.37%). SHB and UGB samples were characterized by a high content of ash, alginate, fucose-containing sulfated polysaccharides (FCSPs), and fucose content of FCSPs, while samples of AB and PI had a high amount of total sugar and crude fiber. PCA result on lipid-soluble components showed a different tendency that SHB and AB samples were located at close proximity and characterized by larger blade size, higher content of chlorophyll, fucoxanthin, carotenoid, PUFA, total n-3 fatty acids, total n-6 fatty acids, and also a lower ratio of n-6 to n-3 (variance: 75.42%). The overview of each samples' chemical characteristics can be valuable knowledge for further development, especially for developing functional ingredients.


Assuntos
Alginatos/análise , Carboidratos/análise , Clorofila/análise , Fibras na Dieta/análise , Fucose/análise , Lipídeos , Polissacarídeos/análise , Sargassum/química , Água , Carotenoides/análise , Ácidos Graxos Insaturados/análise , Indonésia , Solubilidade , Xantofilas/análise
5.
J Environ Manage ; 276: 111308, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32891983

RESUMO

Over the past few decades, partitioning of the surface ocean into ecologically-meaningful spatial domains has been approached using a range of data types, with the aim of improving our understanding of open ocean processes, supporting marine management decisions and constraining coupled ocean-biogeochemical models. The simplest partitioning method, which could provide low-latency information for managers at low cost, remains a purely optical classification based on ocean colour remote sensing. The question is whether such a simple approach has value. Here, the efficacy of optical classifications in constraining physical variables that modulate the epipelagic environment is tested for the tropical Indian Ocean, with a focus on the Chagos marine protected area (MPA). Using remote sensing data, it was found that optical classes corresponded to distinctive ranges of wind speed, wind stress curl, sea surface temperature, sea surface slope, sea surface height anomaly and geostrophic currents (Kruskal-Wallis and post-hoc Tukey honestly significantly different tests, α = 0.01). Between-class differences were significant for a set of sub-domains that resolved zonal and meridional gradients across the MPA and Seychelles-Chagos Thermocline Ridge, whereas between-domain differences were only significant for the north-south gradient (PERMANOVA, α = 0.01). A preliminary test of between-class differences in surface CO2 concentrations from the Orbiting Carbon Observatory-2 demonstrated a small decrease in mean pCO2 with increasing chlorophyll (chl), from 418 to 398 ppm. Simple optical class maps therefore provide an overview of growth conditions, the spatial distribution of resources - from which habitat fragmentation metrics can be calculated, and carbon sequestration potential. Within the 17 year study period, biotic variables were found to have decreased at up to 0.025%a-1 for all optical classes, which is slower than reported elsewhere (Mann-Kendall-Sen regression, α = 0.01). Within the MPA, positive Indian Ocean Dipole conditions and negative Southern Oscillation Indices were weakly associated with decreasing chl, fluorescence line height (FLH), eddy kinetic energy, easterly wind stress and wind stress curl, and with increasing FLH/chl, sea surface temperature, SSH gradients and northerly wind stress, consistent with reduced surface mixing and increased stratification. The optical partitioning scheme described here can be applied in Google Earth Engine to support management decisions at daily or monthly scales, and potential applications are discussed.


Assuntos
Clorofila , Vento , Clorofila/análise , Cor , Oceano Índico , Temperatura
6.
Sci Total Environ ; 741: 140451, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886973

RESUMO

The present study aimed to determine the spatial and temporal variations in trophic state and identify potential causes for these variations in 60 Korean reservoirs. Empirical models were developed using the relations of nutrients (total phosphorus, TP, and total nitrogen, TN) with chlorophyll-a (CHL-a) for efficient lake managements. The empirical models indicated that TP was the key regulating factor for algal growth in agricultural (R2 = 0.69) and power generation (R2 = 0.50) reservoirs. The CHL-a:TP and TN:TP ratios, indicators of phosphorus limitation, were used to validate the phosphorus reduction approach. The mean CHL-a:TP ratio of agricultural reservoirs was 0.60, indicating that algal chlorophyll is potentially limited by TP than any other factors. Agricultural, multipurpose, and power generation reservoirs, based on the N:P ratios, were more P- limited systems than natural lakes and estuarine reservoirs. The trophic state index (TSI) of Korean reservoirs varied between mesotrophy to hypereutrophy based on values of TSI (TP), TSI (CHL-a), and TSI (SD). Agricultural reservoirs were hypereutrophic using the criteria of TSI (CHL-a) and blue-green algae dominated the algal community. Analysis of trophic state index deviation (TSID) indicated that agricultural reservoirs were primarily P limited and other factors had minor effect. In contrast, the trophic status of estuarine and power generation reservoirs and natural lakes was largely modified by non-algal turbidity. Our outcomes may be effectively used for Korean lakes and reservoirs management.


Assuntos
Monitoramento Ambiental , Eutrofização , China , Clorofila/análise , Lagos , Nitrogênio/análise , Nutrientes , Fósforo/análise , República da Coreia
7.
Ecotoxicol Environ Saf ; 205: 111113, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32836153

RESUMO

Eutrophication is a global problem, and bacterial diversity and community composition are usually affected by eutrophication. However, limited information on the ecological significance of bacterial community during algae blooms of rivers has been given, more studies should be focused on the bacterial diversity and distribution characteristics in eutrophic rivers. In this study, we explored the spatial variations of bacterial biomass, community structure, and their relationship with environmental factors in the eutrophic Xiangxi River. The content of Chlorophyll (Chl) was about 16 mg/L in the midstream (S2, S3), which was in the range of light eutrophication. Significant spatial variation of bacterial community structure was found at different sites and depths (p < 0.05), and the driving environmental factor was found to be nitrogen, mainly detected as total nitrogen (TN), Kjeldahl nitrogen (KN), and ammonia nitrogen (NH4+) (p < 0.05). The midstream sites had some significantly different bacteria, including algicidal bacteria and dominant lineages during algal blooms. This result was consistent with the functional prediction, where significant higher abundance of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways was associated with algicidal substances in the midstream. At different water depths, some populations adapted to the surface layer, such as the class Flavobacteriia, and others preferred to inhabit in the bottom layer, such as Betaproteobacteria and Acidobacteria. The bacterial biomass was higher in the bottom layer than that in the surface and middle layer, and temperature and pH were found to be the major driving factors. The bacterial diversity increased with the increasing of depths in most sampling sites according to operational taxonomic units (OTUs), Chao1 and ACE indexes, and PO43- was demonstrated to be the most significant factor. In summary, this study offered the evidence for microbial distribution characteristics across different sites and depths in summer, and its relationship with environmental variables in a eutrophic river.


Assuntos
Monitoramento Ambiental/métodos , Eutrofização , Microbiota , Proteobactérias/crescimento & desenvolvimento , Rios , Biomassa , China , Clorofila/análise , Microbiota/genética , Nitrogênio/análise , Fosfatos/análise , Fósforo/análise , Proteobactérias/classificação , Proteobactérias/genética , RNA Ribossômico 16S/genética , Rios/química , Rios/microbiologia , Estações do Ano , Temperatura
8.
Water Res ; 185: 116236, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32739700

RESUMO

The effect of nutrients on phytoplankton biomass in lakes continues to be a subject of debate by aquatic scientists. However, determining whether or not chlorophyll a (CHL) is limited by phosphorus (P) and/or nitrogen (N) is rarely considered using a probabilistic method in studies of hundreds of lakes across broad spatial extents. Several studies have applied a unified CHL-nutrient relationship to determine nutrient limitation, but pose a risk of ecological fallacy because they neglect spatial heterogeneity in ecological contexts. To examine whether or not CHL is limited by P, N, or both nutrients in hundreds of lakes and across diverse ecological settings, a probabilistic machine learning method, Bayesian Network, was applied. Spatial heterogeneity in ecological context was accommodated by the probabilistic nature of the results. We analyzed data from 1382 lakes in 17 US states to evaluate the cause-effect relationships between CHL and nutrients. Observations of CHL, total phosphorus (TP), and total nitrogen (TN) were discretized into three trophic states (oligo-mesotrophic, eutrophic, and hypereutrophic) to train the model. We found that although both nutrients were related to CHL trophic state, TP was more related to CHL than TN, especially under oligo-mesotrophic and eutrophic CHL conditions. However, when the CHL trophic state was hypereutrophic, both TP and TN were important. These results provide additional evidence that P-limitation is more likely under oligo-mesotrophic or eutrophic CHL conditions and that co-limitation of P and N occurs under hypereutrophic CHL conditions. We also found a decreasing pattern of the TN/TP ratio with increasing CHL concentrations, which might be a key driver for the role change of nutrients. Previous work performed at smaller scales support our findings, indicating potential for extension of our findings to other regions. Our findings enhance the understanding of nutrient limitation at macroscales and revealed that the current debate on the limiting nutrient might be caused by failure to consider CHL trophic state. Our findings also provide prior information for the site-specific eutrophication management of unsampled or data-limited lakes.


Assuntos
Lagos , Teorema de Bayes , China , Clorofila/análise , Clorofila A , Monitoramento Ambiental , Eutrofização , Nitrogênio/análise , Fósforo/análise
9.
Food Chem ; 333: 127500, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32693317

RESUMO

The objectives of this study were to optimize the condition of ultrasonic treatment combined with aqueous chlorine dioxide (ClO2) on nitrate content of spinach by response surface methodology (RSM), and determine the effectiveness of ultrasound (US) and ClO2 alone and in combination, on spinach postharvest quality during 7 days' storage period. The optimal treatment parameters obtained were ultrasonic power (300 W), ClO2 concentration (50 ppm), treatment time (4 min). The combined treatments significantly reduced the nitrate content and maintained better storage quality in terms of total soluble solids (TSS) and ascorbic acid content compared with the individual treatment or untreated. For Chlorophyll content, the combined treatment was significantly higher than the control and ClO2 treatment, but lower than ultrasonic treatment. The results demonstrated that US combined with ClO2 are promising alternatives for the reduction of nitrate content, as well as preserving the quality of stored leafy vegetables.


Assuntos
Compostos Clorados/farmacologia , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Nitratos/análise , Óxidos/farmacologia , Spinacia oleracea/química , Ultrassom/métodos , Ácido Ascórbico/análise , Clorofila/análise , Conservação de Alimentos/instrumentação , Armazenamento de Alimentos , Folhas de Planta/química , Spinacia oleracea/efeitos dos fármacos , Verduras/química , Verduras/efeitos dos fármacos
10.
PLoS One ; 15(6): e0233905, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32502194

RESUMO

Water stress (WS) and heat stress (HS) have a negative effect on soybean plant growth and crop productivity. Changes in the physiological characteristics, proteome, and specific metabolites investigated on molecular and cellular functions were studied in two soybean cultivars exposed to different heat and water stress conditions independently and in combination. Leaf protein composition was studied using 2-DE and complemented with MALDI TOF mass spectrometry. While the two cultivars displayed genetic variation in response to water and heat stress, thirty-nine proteins were significantly altered in their relative abundance in response to WS, HS and combined WS+HS in both cultivars. A majority of these proteins were involved in metabolism, response to heat and photosynthesis showing significant cross-tolerance mechanisms. This study revealed that MED37C, a probable mediator of RNA polymerase transcription II protein, has potential interacting partners in Arabidopsis and signified the marked impact of this on the PI-471938 cultivar. Elevated activities in antioxidant enzymes indicate that the PI-471938 cultivar can restore the oxidation levels and sustain the plant during the stress. The discovery of this plant's development of cross-stress tolerance could be used as a guide to foster ongoing genetic modifications in stress tolerance.


Assuntos
Aclimatação/fisiologia , Secas , Resposta ao Choque Térmico , Proteínas de Plantas/metabolismo , Soja/fisiologia , Clorofila/análise , Clorofila/metabolismo , Regulação da Expressão Gênica de Plantas , Oxirredução , Folhas de Planta/química , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Mapas de Interação de Proteínas/fisiologia , Proteoma/metabolismo , Proteômica , Solo/química , Água/análise
11.
PLoS One ; 15(6): e0233735, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497128

RESUMO

Many fertilization models have been created to scientifically determine the amount of fertilization. With the same purpose, we constructed a nitrogen (N) application model, the leaf value model, which can make N fertilizer decisions in a timely, fast and nondestructive manner during rice planting. However, only one area (A1, Jiuzhou Town, Xixiu District, Guizhou Province) and one cultivar (Qyou6) were involved in the construction of the leaf value model. Its stability and applicability could not be well evaluated. Thus, we chose another area (A2, Jiuzhou Town, Huangping County, Guizhou Province) in Guizhou Province and carried out the experiment by using four cultivars (Nie5you5399, Qyou6, Yixiangyou2115 and Zhongzheyou8) for the leaf value model construction. Compared with the average value of apparent total N uptake (Nz) obtained in 2 years in the A1 area, that in the Qyou6 leaf value model in the A2 area increased by 12%, reaching 635.72 kg ha-1, whereas the corresponding target yield changed slightly, reaching 10,999.90 kg ha-1. Simultaneously, the linear relationship between several good SPAD value-derived indexes (Ys) and apparent N supply of the field (Nx) was still significant or extremely significant in the Qyou6 leaf value model. Compared with the A1 area, it slightly differed, and the R2 of SPADL1 was higher than that of SPADL3×L4/mean. In the leaf value model of the other three cultivars, the relationship between yield and Nx and that between Ys and Nx were significant or extremely significant. The Nz of Yixiangyou2115 and Zhongzheyou8 (618.33 and 617.76 kg ha-1) were close to that of Qyou6 and the corresponding target yields were 10313.36 and 10301.99 kg ha-1, respectively. The Nz and target yield of Nie5you5399 were lowest at 546.63 and 10680.24 kg ha-1, respectively. In general, this study showed that relationships used in the construction of leaf value model had certain stability and applicability to difference areas and cultivars. The leaf value model can be considered in N fertilizer decision-making of rice planting management.


Assuntos
Fertilizantes , Modelos Biológicos , Nitrogênio/administração & dosagem , Oryza/fisiologia , Folhas de Planta/fisiologia , Clorofila/análise , Produção Agrícola/métodos , Oryza/anatomia & histologia , Oryza/química , Folhas de Planta/química , Solo/química
12.
Nat Commun ; 11(1): 3108, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32561737

RESUMO

In the Southern Ocean, large-scale phytoplankton blooms occur in open water and the sea-ice zone (SIZ). These blooms have a range of fates including physical advection, downward carbon export, or grazing. Here, we determine the magnitude, timing and spatial trends of the biogeochemical (export) and ecological (foodwebs) fates of phytoplankton, based on seven BGC-Argo floats spanning three years across the SIZ. We calculate loss terms using the production of chlorophyll-based on nitrate depletion-compared with measured chlorophyll. Export losses are estimated using conspicuous chlorophyll pulses at depth. By subtracting export losses, we calculate grazing-mediated losses. Herbivory accounts for ~90% of the annually-averaged losses (169 mg C m-2 d-1), and phytodetritus POC export comprises ~10%. Furthermore, export and grazing losses each exhibit distinctive seasonality captured by all floats spanning 60°S to 69°S. These similar trends reveal widespread patterns in phytoplankton fate throughout the Southern Ocean SIZ.


Assuntos
Monitorização de Parâmetros Ecológicos/métodos , Cadeia Alimentar , Camada de Gelo/microbiologia , Fitoplâncton/fisiologia , Água do Mar/microbiologia , Algoritmos , Clorofila/análise , Clorofila/metabolismo , Conjuntos de Dados como Assunto , Monitorização de Parâmetros Ecológicos/instrumentação , Eutrofização , Herbivoria , Oceanos e Mares , Tecnologia de Sensoriamento Remoto/instrumentação , Tecnologia de Sensoriamento Remoto/métodos , Estações do Ano , Análise Espaço-Temporal
13.
Sci Total Environ ; 736: 139362, 2020 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-32497893

RESUMO

Prevention of excessive periphyton standing crop (quantified as chlorophyll a) is among primary objectives for river management. Defensible instream nutrient criteria to achieve periphyton chlorophyll a targets at the site scale require robust predictive models. Such models have proved elusive because peak chlorophyll a depends on multiple factors in addition to nutrients. A key predictor may be accrual period, which depends on river flow variability and the flow magnitudes (effective flows, EF) at which periphyton biomass removal is initiated. In this study we used a seven-year dataset from 44 gravel-bed river sites in the Manawatu-Whanganui region, New Zealand, to explore the relative importance of accrual period, nutrients, and other variables in explaining peak chlorophyll a, using a regression approach. We also assessed the effect of combining data from multiple years. Previous empirical studies have used a universal flow metric (3 × median flow) to define accrual period (Da3). We calculated site-specific EF, which varied from 2 × to 15 × median flow. Accrual period based on EF (DaEF) outperformed Da3 in models. However, in the study region, more variance in chlorophyll a was explained by conductivity (EC) and dissolved inorganic nitrogen (DIN) than by DaEF. The best models derived from multi-year datasets included EC, DIN and DaEF as predictors and accounted for up to 82% of the variance in peak chlorophyll a. Models from annual data were weaker and more variable in strength and predictors. The models indicated that EC and DaEF should be considered when setting DIN criteria for periphyton outcomes in the study region. The principles we used in developing the models may have broad relevance to the management of periphyton in other regions.


Assuntos
Perifíton , Clorofila/análise , Clorofila A , Monitoramento Ambiental , Nova Zelândia , Nitrogênio , Qualidade da Água
14.
J Vis Exp ; (160)2020 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-32597841

RESUMO

Satellite observations offer a great approach to investigate the features of major marine parameters, including sea surface chlorophyll (CHL), sea surface temperature (SST), sea surface height (SSH), and factors derived from these parameters (e.g., fronts). This study shows a step-by-step procedure to use satellite observations to describe major parameters and their relationships in seasonal and anomalous fields. This method is illustrated using satellite datasets from 2002-2017 that were used to describe the surface features of the South China Sea (SCS). Due to cloud coverage, monthly averaged data were used in this study. The empirical orthogonal function (EOF) was applied to describe the spatial distribution and temporal variabilities of different factors. The monsoon wind dominates the variability in the basin. Thus, wind from the reanalysis dataset was used to investigate its driving force on different parameters. The seasonal variability in CHL was prominent and significantly correlated with other factors in a majority of the SCS. In winter, a strong northeast monsoon induces a deep mixed layer and high level of chlorophyll throughout the basin. Significant correlation coefficients were found among factors at the seasonal cycle. In summer, high CHL levels were mostly found in the western SCS. Instead of a seasonal dependence, the region was highly dynamic, and factors correlated significantly in anomalous fields such that unusually high CHL levels were associated with abnormally strong winds and intense frontal activities. The study presents a step-by-step procedure to use satellite observations to describe major parameters and their relationships in seasonal and anomalous fields. The method can be applied to other global oceans and will be helpful for understanding marine dynamics.


Assuntos
Clorofila/análise , Monitoramento Ambiental , Oceanos e Mares , Astronave , China , Estações do Ano , Temperatura , Vento
15.
Artigo em Inglês | MEDLINE | ID: mdl-32474384

RESUMO

High temperatures limit the successful cultivation of the Hylocereus species on a global basis. We aimed to investigate the degree of heat tolerance in three species, namely, the diploids Hylocereus undatus and H. monacanthus, and the tetraploid H. megalanthus, and nine of their interspecific-interploid hybrids. Rooted cuttings were exposed to heat stress (45/35 °C) or control conditions (25/20 °C) for eight days. Initially, the plants were screened for their tolerance to heat stress and ranked into four heat tolerance categories: good tolerance, moderate tolerance, low tolerance, or sensitive, according to the decrease in the maximum quantum efficiency of photosystem II (Fv/Fm) and visual stem damage. The physiological and biochemical performances of the parental species and of three hybrids representing three different heat-tolerance categories were further analyzed in depth. H. megalanthus (classified as heat sensitive) showed a 65% decrease in Fv/Fm and severe visual stem damage, along with a marked reduction in total chlorophyll content, a large increase in malondialdehyde, and inhibition of catalase activity. H. undatus and H. monacanthus, (classified as low-tolerance species) exhibited slight stem "liquification." The good-tolerance hybrid Z-16 exhibited the best performance under heat stress (21% decrease in Fv/Fm) and the absence of stem damage, coupled with a small decrease in total chlorophyll content, a slight increase in malondialdehyde, high antioxidant activity, and proline accumulation progressing with time. Our findings revealed that most of the hybrids performed better than their parental species, indicating that our breeding programs can provide Hylocereus cultivars suitable for cultivation in heat-challenging regions.


Assuntos
Cactaceae/fisiologia , Temperatura Alta , Estresse Fisiológico , Clorofila/análise , Complexo de Proteína do Fotossistema II/fisiologia , Melhoramento Vegetal
16.
Environ Monit Assess ; 192(7): 417, 2020 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-32506388

RESUMO

This study assessed the spatial and temporal nutrient variability in the El Fuerte River basin in northwestern Mexico, considering its effects on the water trophic status as well as the nutrient loading to the Gulf of California. Physicochemical parameters, inorganic species of nitrogen, phosphate, total nitrogen, total phosphorus, and chlorophyll-a (chl-a) were quantified at 16 selected sites along the river in April (dry season) and October (rainy season) 2017. Mean concentrations of nutrients during dry and rainy seasons were 36.3 ± 24.1 and 55.1 ± 74.6 µg L-1 of total ammonia nitrogen, 3.4 ± 3.6 and 4.5 ± 3.5 µg L-1 of NO2--N, 190.8 ± 256.0 and 163.6 ± 261.0 µg L-1 of NO3--N, 42.4 ± 44.2 and 104.9 ± 76.2 µg L-1 of PO43--P, 1.0 ± 1.3 and 691 ± 2242 mg L-1 of TN, 0.06 ± 0.06 and 0.08 ± 0.09 mg L-1 of TP, and 0.9 ± 0.6 and 2.0 ± 0.9 µg L-1 of chl-a with significant differences (p < 0.05) between sites and seasons. When waters are transported downstream, nutrient levels are enriched by 4 to 35 times compared to those upstream due to increased population and agriculture downstream, confirming the hypothesis of the study. The calculated TN and TP fluxes were 1.23 × 104 and 3.57 × 101 ton year-1, respectively. Factor analysis indicated that inorganic nitrogen species and phosphorus are the main factors affecting the river water quality. Despite N excess during the rainy season, the river reached mesotrophic waters due to phosphorus limitation. This suggests the need to establish a water quality monitoring program to understand the vulnerability of the river course to changes in its trophic state.


Assuntos
Monitoramento Ambiental , Nitrogênio , Fósforo , Rios , Poluentes Químicos da Água , Clorofila/análise , México , Nitrogênio/análise , Nutrientes/análise , Fósforo/análise , Rios/química , Estações do Ano , Poluentes Químicos da Água/análise
17.
PLoS One ; 15(5): e0232051, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433697

RESUMO

Dalbergia odorifera T. Chen seedlings do not grow well in the typical red soils of tropical regions. Eighteen culture substances filled with different substrate combinations and proportions of red soil, coconut coir powder, deciduous leaf powder, and sand were used as to determine their effects on the growth, root system development, dry matter accumulation and allocation, leaf relative electrolyte leakage, chlorophyll content, root superoxide dismutase activity, root malondialdehyde content, and total soluble sugar content of D. odorifera. Results demonstrated that different substrate combinations and proportions had different effects on the performance of D. odorifera. All mixed substrates were better than any single substrate. The suitable substrate combinations and proportions of sand, coconut coir powder, and deciduous leaf powder mixed with red soil improved the growth, root architecture, and physiological characteristics of D. odorifera seedling. For example, groups C1-2 (coconut coir/red soil = 2/2, v/v, the same below) and C3-2 (red soil/sand = 2/2) exerted the best effects on plant growth and biomass accumulation. Groups C1-2, C2-2 (deciduous leaf powder/red soil = 2/2), and C3-2 remarkably enhanced root system development. Group C6 (coconut coir/red soil/sand = 1/1/1) substantially promoted root nodule development. Group C3-1 (red soil/sand = 3/1) exhibited the best effects on physiological characteristics. On the basis of the comprehensive evaluation of Euclid's multidimensional space mathematical model, we found that the suitable substrate combinations followed the order of C1-2 > C3-1 > C2-2. This research provides scientific guidance for the proper seedling culture of D. odorifera and the rational utilization of solid wastes such as coconut coir and deciduous leaves of Ficus elastica.


Assuntos
Dalbergia/fisiologia , Solo/química , Biomassa , Clorofila/análise , Dalbergia/anatomia & histologia , Dalbergia/crescimento & desenvolvimento , Eletrólitos/metabolismo , Fertilizantes/análise , Malondialdeído/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/enzimologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/anatomia & histologia , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Superóxido Dismutase/metabolismo
18.
Food Chem ; 326: 126974, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32413759

RESUMO

In this study, flaxseeds roasted at microwave (MW) powers of 180, 360 and 540 W for 5 and 10 min were evaluated for their influence on oil yield, chemical properties, carotenoid and chlorophyll contents, total phenolic content (TPC), radical scavenging activity (RSA), oxidative stability index (OSI), fatty acid composition and Maillard reaction products (MRPs). MW roasting at 540 W for 10 min significantly increased the oil yield, TPC, OSI, RSA, a* value, browning index, carotenoid and chlorophyll contents while decreased the L* and b* values of flaxseed oil (FSO). MRPs were detected only in oil of flaxseeds roasted at 540 W for 10 min. The level of stearic, palmitic, oleic, linoleic and α-linolenic acids were slightly changed and FTIR spectra showed minor variation in peak intensities of oils from different MW roasted flaxseeds. MW roasting (540 W for 10 min) is recommended for improving quality and stability characteristics of FSO.


Assuntos
Ácidos Graxos/análise , Linho/química , Óleo de Semente do Linho/química , Micro-Ondas , Antioxidantes/química , Carotenoides/análise , Carotenoides/química , Clorofila/análise , Clorofila/química , Ácidos Graxos/química , Armazenamento de Alimentos , Produtos Finais de Glicação Avançada/análise , Produtos Finais de Glicação Avançada/química , Oxirredução , Fenóis/análise , Fenóis/química , Sementes/química , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Plant Mol Biol ; 103(4-5): 561-580, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32405802

RESUMO

KEY MESSAGE: CmHKT1;1 selectively exports Na+ from plant cells. Upon NaCl stress, its expression increased in a salt-tolerant melon cultivar. Overexpression of CmHKT1;1 increased transgenic Arabidopsis salt tolerance through improved K+/Na+ balance. High-affinity K+ transporters (HKTs) are thought to be involved in reducing Na+ in plant shoots under salt stress and modulating salt tolerance, but their function in a moderately salt-tolerant species of melon (Cucumis melo L.) remains unclear. In this study, a Na+ transporter gene, CmHKT1;1 (GenBank accession number: MK986658), was isolated from melons based on genome data. The transcript of CmHKT1;1 was relatively more abundant in roots than in stems or leaves from melon seedlings. The tobacco transient expression system showed that CmHKT1;1 was plasma-membrane localized. Upon salt stress, CmHKT1;1 expression was more strongly upregulated in a salt-tolerant melon cultivar, 'Bingxuecui' (BXC) compared with a salt-sensitive cultivar, 'Yulu' (YL). Electrophysiological evidence demonstrated that CmHKT1;1 only transported Na+, rather than K+, when expressed in Xenopus laevis oocytes. Overexpression of CmHKT1;1 increased salt sensitivity in Saccharomyces cerevisiae and salt tolerance in Arabidopsis thaliana. Under NaCl treatments, transgenic Arabidopsis plants accumulated significantly lower concentrations of Na+ in shoots than wild type plants and showed a better K+/Na+ balance, leading to better Fv/Fm, root length, biomass, and enhanced plant growth. The CmHKT1;1 gene may serve as a useful candidate for improving crop salt tolerance.


Assuntos
Arabidopsis/metabolismo , Cucumis melo/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Potássio/metabolismo , Sódio/metabolismo , Arabidopsis/genética , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Clorofila/análise , Clonagem Molecular , Cucumis melo/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana Transportadoras/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Raízes de Plantas/metabolismo , Brotos de Planta/genética , Saccharomyces cerevisiae/genética , Tolerância ao Sal , Plântula/genética , Plântula/metabolismo , Alinhamento de Sequência , Análise de Sequência de Proteína , Cloreto de Sódio/metabolismo , Estresse Fisiológico/genética , Estresse Fisiológico/fisiologia , Simportadores/genética , Simportadores/metabolismo , Tabaco/genética , Tabaco/metabolismo
20.
Chemosphere ; 254: 126846, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32361542

RESUMO

The Water Sediment Regulation Scheme (WSRS) is a unique engineering measure that has been regularly performed to reduce reservoir sedimentation and increase the flood capacity of the Yellow River in China since 2002. As a side effect, the WSRS greatly increases the monthly input flux of nutrients to the Bohai Sea (BHS) in summer, potentially exacerbating eutrophication levels therein and subsequently affecting the growth of phytoplankton. However, its influence on the Chlorophyll-a (Chl-a) dynamics over the BHS is still poorly understood. In this study, two approaches were adopted to investigate it: 1) long-term in-situ observations and satellite-derived data of surface Chl-a were used to study its seasonal variations before and since 2002, and 2) one 1D physical-biological coupled model was developed to evaluate the impact of WSRS on seasonal Chl-a. The results showed that the surface Chl-a exhibited two peaks in spring and autumn until 2002, but has exhibited only one peak in spring-summer since 2002. Satellite-derived Chl-a concentrations in spring-summer since 2002 have increased by 56% compared to those until 2002. The simulated results showed that the change in Yellow River discharge induced by the WSRS has resulted in the appearance of high concentrations of Chl-a in summer over the Central Bohai Sea since 2002. The WSRS increased the ratio of added Chl-a owing to the riverine nutrients to total Chl-a by 19% compared to that until 2002. Overall, WSRS greatly affects the seasonal cycling of Chl-a in the Bohai Sea, and the side effect needs to be considered.


Assuntos
Clorofila A/análise , Monitoramento Ambiental , China , Clorofila/análogos & derivados , Clorofila/análise , Clima , Conservação dos Recursos Hídricos , Eutrofização , Fitoplâncton , Rios , Estações do Ano , Água , Poluição da Água/prevenção & controle
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