Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 129
Filtrar
1.
Bull Environ Contam Toxicol ; 105(5): 742-749, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33000334

RESUMO

Inland lakes are important ecosystems for the carbon cycle at both regional and global scales. However, a knowledge gap still exists about the correlations between the partial pressure of CO2 (pCO2) and nutrient dynamics in lakes. In this study, we analysed the long-term dynamics of nutrient and pCO2 in Taihu Lake. Strong spatial heterogeneity was observed with highest nutrient concentrations occurring in the River mouth and significant lower concentrations (p < 0.01) occurring in East Taihu and Other zone. For pCO2, the average values were 1136.81 ± 1240.16 µatm, 433.07 ± 305.45 µatm, and 487.05 ± 414.02 µatm in Rive mouth, East Taihu, and Other zone, respectively. Statistical analysis revealed that pCO2 was significantly and positively related to nutrient (TN: total nitrogen and NH4+: ammonium) concentrations (p < 0.01), but negatively related to Chla (Chlorophyll a) concentrations in River mouth and Other zone (p < 0.01). The parallelism of nutrient concentrations and pCO2 in Taihu Lake highlights the dual effects of external pollution inputs from the surrounding catchment. In addition, progressive mitigation was found for not only nutrients but also pCO2, which was attributed to the previous effort in the environmental protections in Taihu Lake basin. Our results also suggest the importance of long-term monitoring for the future assessment of anthropogenic impacts on nutrient and CO2 dynamics in freshwater lakes.


Assuntos
Dióxido de Carbono/análise , Monitoramento Ambiental/métodos , Lagos/química , Nitrogênio/análise , Fósforo/análise , Poluentes Químicos da Água/análise , China , Clorofila A/análise , Ecossistema , Eutrofização , Rios/química
2.
Nat Commun ; 11(1): 4658, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938931

RESUMO

Dimethylsulfoniopropionate (DMSP) is an important marine osmolyte. Aphotic environments are only recently being considered as potential contributors to global DMSP production. Here, our Mariana Trench study reveals a typical seawater DMSP/dimethylsulfide (DMS) profile, with highest concentrations in the euphotic zone and decreased but consistent levels below. The genetic potential for bacterial DMSP synthesis via the dsyB gene and its transcription is greater in the deep ocean, and is highest in the sediment.s DMSP catabolic potential is present throughout the trench waters, but is less prominent below 8000 m, perhaps indicating a preference to store DMSP in the deep for stress protection. Deep ocean bacterial isolates show enhanced DMSP production under increased hydrostatic pressure. Furthermore, bacterial dsyB mutants are less tolerant of deep ocean pressures than wild-type strains. Thus, we propose a physiological function for DMSP in hydrostatic pressure protection, and that bacteria are key DMSP producers in deep seawater and sediment.


Assuntos
Bactérias/genética , Bactérias/metabolismo , Água do Mar/química , Água do Mar/microbiologia , Compostos de Sulfônio/metabolismo , Bactérias/isolamento & purificação , Clorofila A/análise , Clorofila A/metabolismo , Genes Bacterianos , Sedimentos Geológicos/química , Pressão Hidrostática , Marinobacter/genética , Marinobacter/isolamento & purificação , Marinobacter/metabolismo , Metagenoma , Mutação , Oceanos e Mares , Prochlorococcus/genética , Prochlorococcus/isolamento & purificação , Prochlorococcus/metabolismo , RNA Ribossômico 16S , Sulfetos/análise , Sulfetos/metabolismo , Compostos de Sulfônio/análise , Synechococcus/genética , Synechococcus/isolamento & purificação , Synechococcus/metabolismo
3.
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
4.
An Acad Bras Cienc ; 92(2): e20180962, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32321032

RESUMO

Benthic macroinvertebrates are organisms that are recognized as water quality bio-indicators. A wide variety of indices and metrics have been shown to respond to a variety of anthropogenic impacts, usually under a general condition of environmental impairment. The absence of a clear distinction in the relations between specific pollutants and biotic variables is very common and can lead to biased interpretation of biomonitoring. The aims of this research were to test taxonomic and non-taxonomic responses to specific environmental conditions instead to general conditions. For this purpose, we estimated the theoretical toxicity by comparing toxicity values published by EPA with metal concentrations in water and sediments. Then we tested the responses of biological variables to toxicity and other environmental conditions using the linear mixed effects models approach. We generated 32 models considering 24 different biological metrics and indices that were grouped in five levels. Taxonomic and abundance metrics were best predictor than functional or tolerance-based indexes. The strongest model was that which considered subfamily taxonomic resolution responding to Al_w and Cr_s.


Assuntos
Invertebrados/química , Metais/toxicidade , Poluentes Químicos da Água/análise , Animais , Brasil , Clorofila A/análise , Ecossistema , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Invertebrados/classificação , Modelos Lineares , Fósforo/análise , Análise de Componente Principal , Rios/química
5.
Environ Monit Assess ; 192(5): 316, 2020 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-32342228

RESUMO

Zayandeh-Rud River is the only permanent river in the central plateau of Iran. This river has been subject to an extensive discharge of wastewater and effluents from several point and nonpoint pollution sources. Accordingly, sediment quality of Zayandeh-Rud River in Varzaneh region, were studied. Algae and the sediment were sampled through 3 replications at 6 stations in the downstream after crossing through the Isfahan city and reaching Gavkhuni international wetland. Chlorophyll content and As, Pb, and Cd concentrations were measured in each sample Cladophora sp. and Oscillatoria sp. were identified using standard identification keys. The mean concentrations of metals in all stations exceeded background levels. Mean concentration of arsenic (162.9 mg/kg) in the sediment is about 31 times more than the ISQG standard (5.9 mg/kg) and considerably higher than the similar studies in Iran and other regions of the world. The mean concentration of As in algae samples is higher than the most polluted areas of the world. The mean concentration of Pb in the sediment (19.69 mg/kg) is lower than the ISQGs standard (35 mg/kg) and most of the studied river in north of Iran such as Chalous, Baboul-Rud, Gorgan-Rud (North), Khiav (North West), and Anzali wetland. The mean concentration of Cd in the sediment (2.11 mg/kg) is significantly higher than ISQG standard (0.6 mg/kg and some north highly polluted wetlands of Iran such as Anzali. There is a significant positive correlation between the mean concentrations of As and Pb in the sediment and Cladophora sp. tissue, and a negative one between the mean concentration of Pb in the sediment and chlorophyll b/a. There are significant negative correlations between the mean concentration of As in the sediment and chlorophyll a, and the total chlorophyll concentration in Oscillatoria sp. The results of Muller index indicate that the concentrations of Pb, Cd, and As in all stations occur in the Unpolluted, Moderate/Heavy, and Heavy/Extreme groups, respectively. Degree of contamination and modified degree of contamination show very high degree of pollution in the studied area. RI in all the stations showed very high ecological risk. The bioaccumulation factor for all metals in both algae is less than one. So, these two species may not be described as heavy metal accumulators. This study is an alarm for the Zayandeh-Rud River as the most important freshwater source for the Iranian Plateau. Graphical abstract.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos , Metais Pesados , Poluentes Químicos da Água , Clorofila A/análise , Clorófitas/química , Cidades , Sedimentos Geológicos/química , Irã (Geográfico) , Metais Pesados/análise , Medição de Risco , Poluentes Químicos da Água/análise
6.
PLoS One ; 15(4): e0231104, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32255794

RESUMO

Over the last three decades corals have declined precipitously in the Florida Keys. Their population decline has prompted restoration effort. Yet, little effort has been invested in understanding the contemporary niche spaces of coral species, which could assist in prioritizing conservation habitats. We sought to predict the probability of occurrence of 23 coral species, including the critically endangered Acropora cervicornis, using observations at 985 sites from 2011-2015. We ran boosted regression trees to evaluate the relationship between the presence of these corals and eight potential environmental predictors: (i) bathymetry (m), (ii) mean of daily sea surface temperature (SST) (°C), (iii) variance of SST (°C), (iv) range of SST (°C), (v) chlorophyll-a concentration (mg m3), (vi) turbidity (m-1), (vii) wave energy (kJ m-2), and (viii) distance from coast (km). The Marquesas and the lower and upper Florida Keys were predicted to support the most suitable habitats for the 23 coral species examined. A. cervicornis had one of the smallest areas of suitable habitat, which was limited to the lower and upper Florida Keys, the Dry Tortugas, and nearshore Broward-Miami reefs. The best environmental predictors of site occupancy of A. cervicornis were SST range (4-5°C) and turbidity (K490 between 0.15-0.25 m-1). Historically A. cervicornis was reported in clear oligotrophic waters, although the present results find the coral species surviving in nearshore turbid conditions. Nearshore, turbid reefs may shade corals during high-temperature events, and therefore nearshore reefs in south Florida may become important refuges for corals as the ocean temperatures continue to increase.


Assuntos
Distribuição Animal , Antozoários/fisiologia , Recifes de Corais , Espécies em Perigo de Extinção/estatística & dados numéricos , Recuperação e Remediação Ambiental , Animais , Clorofila A/análise , Espécies em Perigo de Extinção/tendências , Monitoramento Ambiental/estatística & dados numéricos , Florida , Temperatura Alta/efeitos adversos , Água do Mar/análise , Água do Mar/química
7.
Mar Environ Res ; 157: 104934, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32275514

RESUMO

Phytoplankton response to interannual climate variability has an important regulatory effect on the regional marine ecological environment and carbon cycle. In this study, we focused on the phytoplankton response in the upwelling region of the Sulu Ridge to the El Niño-Southern Oscillation (ENSO) based on monthly remote sensing chlorophyll-a concentration (Chl-a) and physical parameters from various sources from September 1997 to December 2017. We selected two El Niño events in 1997/1998 and 2015/2016 and two La Niña events in 1998/1999 and 2010/2011 to examine the response of Chl-a to ENSO events in this region. Results showed that El Niño and La Niña could enhance and inhibit the growth of phytoplankton in the Sulu Ridge in winter, respectively. For other seasons, the influence of ENSO on the Chl-a was inconsistent. Specifically, during El Niño events, the largest Chl-a increases occurred in winter, and the low sea surface temperature (SST) center appeared northwest of Sulu Ridge. The significant decrease of SST (~1.5 °C) during El Niño events in winter in the northeastern Sulu Ridge was mainly caused by the increase in Ekman transport (ET) and Ekman pumping velocity (EPV), which brought nutrient-rich subsurface water to the surface layer through the thin barrier layer and enhanced Chl-a. During La Niña events, the SST was higher (~0.8 °C) than the average and the high SST center generally appeared in the middle of the Sulu Ridge with the east-west direction in winter, which was resulted from the intensification of barrier layer thickness (BLT) and the decrease of ET, thus reducing the Chl-a. The different responses to El Niño and La Niña events indicate the high sensitivity of Chl-a in this region to the ENSO.


Assuntos
El Niño Oscilação Sul , Fitoplâncton/crescimento & desenvolvimento , Clorofila A/análise , Filipinas , Estações do Ano
8.
Opt Express ; 28(3): 2661-2682, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32121950

RESUMO

A methodology is developed for deriving consistent ocean biological and biogeochemical products from multiple satellite ocean color sensors that have slightly different sensor spectral characteristics. Specifically, the required coefficients for algorithm modifications are obtained using the hyperspectral in situ optical measurements from the Marine Optical Buoy (MOBY) in the water off Hawaii. It is demonstrated that using the proposed approach for modifying ocean biological and biogeochemical algorithms, satellite-derived ocean property data over the global open ocean are consistent from multiple satellite sensors, although their corresponding sensor-measured normalized water-leaving radiance spectra nLw(λ) are different. Therefore, the proposed approach allows satellite-derived ocean biological and biogeochemical products to be consistent and can therefore be routinely merged from various satellite ocean color sensors. The proposed approach can be applied to any satellite algorithms that use the input of sensor-measured nLw(λ) spectra.


Assuntos
Monitoramento Ambiental/instrumentação , Oceanos e Mares , Comunicações Via Satélite , Algoritmos , Clorofila A/análise , Cor , Óptica e Fotônica
9.
Opt Express ; 28(3): 4274-4285, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32122083

RESUMO

In vivo chlorophyll fluorescence (ChlF) can serve as a reasonable estimator of in situ phytoplankton biomass with the benefits of efficiently and affordably extending the global chlorophyll (Chl) data set in time and space to remote oceanic regions where routine sampling by other vessels is uncommon. However, in vivo ChlF measurements require correction for known, spurious biases relative to other measures of Chl concentration, including satellite ocean color retrievals. Spurious biases affecting in vivo ChlF measurements include biofouling, colored dissolved organic matter (CDOM) fluorescence, calibration offsets, and non-photochemical quenching (NPQ). A more evenly distributed global sampling of in vivo ChlF would provide additional confidence in estimates of uncertainty for satellite ocean color retrievals. A Saildrone semi-autonomous, ocean-going, solar- and wind-powered surface drone recently measured a variety of ocean and atmospheric parameters, including ChlF, during a 60-day deployment in mid-2018 in the California Current region. Correcting the Saildrone ChlF data for known biases, including deriving an NPQ-correction, greatly improved the agreement between the drone measurements and satellite ocean color retrievals from MODIS-Aqua and VIIRS-SNPP, highlighting that once these considerations are made, Saildrone semi-autonomous surface vehicles are a valuable, emerging data source for ocean and ecosystem monitoring.


Assuntos
Clorofila A/análise , Oceanos e Mares , Processos Fotoquímicos , Comunicações Via Satélite , Cor , Fluorescência , Geografia , México , Fatores de Tempo
10.
PLoS One ; 15(2): e0228873, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32040527

RESUMO

The manila clam Ruditapes philippinarum is widely distributed in the sandy mud sediments of tidal flats and plays a role in seawater purification by filtering suspended organic matter. This study was designed to evaluate differences in seawater purification based on the filtration rate of the manila clam in terms of particulate organic matter (POM) between two tidal flats with different hydrographic regimes. In situ experiments were carried out at Geunso and Sihwa tidal flats, along the west coast of Korea. The amount of POM removed from the water column by the feeding activity of the clam was measured in the field using a closed circulation chamber. The filtration rate of clams for POM at Sihwa tidal flat (2.86 for POC, 2.29 for PON and 5.46 L h-1 gDW-1 for Chl a) was higher than that at Geunso tidal flat (0.61 for POC, 0.89 for PON and 2.54 L h-1 gDW-1 for Chl a) which resulted from differences in the hydrographic regime, including tide characteristics, current speed and submergence time, and food quantity and quality. The current speed was much greater at Geunso tidal flat than at Sihwa tidal flat, but the submergence time by tide was longer at the latter site than the former, resulting in different feeding times for clams. The food quantity in terms of chlorophyll a was higher at Sihwa tidal flat than at Geunso tidal flat, and the food quality based on the C/N ratio of POM was better at the former site than the latter, with values of 12.8 and 15.6, respectively. These findings suggest that hydrographic regime could be important in understanding in situ filtration rates of R. philippinarum.


Assuntos
Bivalves/fisiologia , Animais , Clorofila A/análise , Comportamento Alimentar/fisiologia , Cadeia Alimentar , Sedimentos Geológicos/análise , Hidrodinâmica , Material Particulado/análise , República da Coreia , Água do Mar/análise , Poluentes Químicos da Água/análise , Purificação da Água
11.
Artigo em Inglês | MEDLINE | ID: mdl-32102314

RESUMO

In the rapid development of marine aquaculture, the water quality of aquatic environments is regarded as a main limiting factor. Therefore, it is necessary to assess the water quality and environmental conditions in marine aquaculture areas and find out the main influencing factors regarding damage to the water quality environment. In the present research, pond aquaculture and cage aquaculture areas were sampled in May, August and November in 2018. Nine water quality indicators were detected, including pH, temperature, salinity, dissolved oxygen, molybdate-reactive phosphorus, chemical oxygen demand, chlorophyll a, inorganic nitrogen and antibiotic resistance genes (ARGs). Principal component analysis (PCA) was used to analyze the water quality conditions, spatial-temporal changes, and the driving factors in pond and cage aquaculture areas. The results showed that three main components were extracted from the pond aquaculture area, which explained 66.82% of the results, the most relevant factors are salinity, dissolved oxygen and ARGs. For the cage aquaculture area, three main components were extracted which can account for 72.99% of the results, the most relevant factors are chlorophyll a, salinity and dissolved oxygen. The comprehensive scores of the principal components indicated that the heaviest polluted months in pond and aquaculture areas were August and November, respectively. The water quality of the pond aquaculture area is mainly limited by the volume of the pond, while aquaculture activities and seasonality are the main factors for cage aquaculture. ARGs in cage culture areas showed more variety and frequency compared with pond culture areas, which indicated that terrestrial input might be one of the sources for ARGs occurrence. The results would be helpful for the relevant authorities to select water quality monitoring parameters in marine aquaculture areas.


Assuntos
Aquicultura , Monitoramento Ambiental , Qualidade da Água , Análise da Demanda Biológica de Oxigênio , Clorofila A/análise , Farmacorresistência Bacteriana/genética , Genes Bacterianos , Nitrogênio/análise , Oxigênio/análise , Fósforo , Tanques , Salinidade
12.
J Photochem Photobiol B ; 203: 111768, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931383

RESUMO

In vitro callus cultures of Verbena officinalis L. were maintained on solid Murashige and Skoog medium, enriched with 1 mg dm-3 BA and 1 mg dm-3 IBA under LED lights (red, blue, red/blue 70%/30%), in darkness and under control fluorescent lamps. The measurements of 2 phenylpropanoid glycosides (verbascoside and isoverbascoside) and 23 phenolic acids were performed in methanolic extracts from the biomass collected after 2-, 3- and 4-week growth cycles using the HPLC-DAD method. The presence of verbascoside, isoverbascoside and additionaly 7 phenolic acids (protocatechuic, chlorogenic, vanillic, caffeic, ferulic, o-coumaric and m-coumaric acids) was confirmed in all extracts. Blue and red/blue lights stimulated the accumulation of verbascoside (max. of 6716 and 6023 mg 100 g-1 DW after a 4-week growth cycle) and isoverbascoside (max. 333 and 379 mg 100 g-1 DW also after 4 weeks). The maximum amounts of verbascoside and isoverbascoside were respectively 1.8- and 7.0-fold higher than under the control conditions. Phenolic acids were accumulated in different amounts, and the maximum total amounts ranged from 36 to 65 mg 100 g-1 DW. LED lights also stimulated their accumulation in comparison with darkness and control. The main phenolic acids included: m-coumaric acid (max. 39 mg 100 g-1 DW), ferulic acid (max. 12 mg 100 g-1 DW), and protocatechuic acid (max. 13 mg 100 g-1 DW). Additionally, the quantities of photosynthetic pigments (chlorophyll a, b and carotenoids) were estimated in acetonic extracts using spectrophotometry. Red/blue light stimulated the biosynthesis of pigments (max. total content 287 µg g-1 FW after 4-week growth cycles). This is the first study describing the effect of LED lights on the production of phenylpropanoid glycosides and phenolic acids in V. officinalis callus cultures. Very high amounts of verbascoside and isoverbascoside are interesting from a practical point of view.


Assuntos
Glucosídeos/metabolismo , Hidroxibenzoatos/metabolismo , Luz , Fenóis/metabolismo , Verbena/metabolismo , Biomassa , Carotenoides/análise , Clorofila/análise , Clorofila A/análise , Cromatografia Líquida de Alta Pressão , Glucosídeos/análise , Hidroxibenzoatos/análise , Fenóis/análise , Fotossíntese/efeitos da radiação , Análise de Componente Principal , Análise de Regressão , Espectrofotometria
13.
Bioengineered ; 11(1): 141-153, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-31994978

RESUMO

Cell immobilization on the magnetic nanoparticles (MNPs) and magnetic harvesting is a novel approach for microalgal cells separation. To date, the effect of these nanoparticles on microalgal cells was only studied over a short period of time. More studies are hence needed for a better understanding of the magnetic harvesting proposes or environmental concerns relating to long-term exposure to nanoparticles. In this study, the impact of various concentrations of MNPs on the microalgal cells growth and their metabolic status was investigated over 12 days. More than 60% reduction in mitochondrial activity and pigments (chlorophyll a, chlorophyll b, and carotenoids) content occurred during the first 6 days of exposure to ≥50 µg/mL nanoparticles. However, more than 50% growth inhibitory effect was seen at concentrations higher than 400 µg/mL. Exposure to MNPs gradually induced cellular adaptation and after about 6 days of exposure to stress generating concentrations (˂400 µg/mL) of IONs, microalgae could overcome the imposed damages. This work provides a better understanding regarding the environmental impact of MNPs and appropriate concentrations of these particles for future algal cells magnetic immobilization and harvesting.


Assuntos
Chlorella vulgaris/química , Nanopartículas/química , Células Imobilizadas/química , Células Imobilizadas/metabolismo , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Clorofila/análise , Clorofila/metabolismo , Clorofila A/análise , Clorofila A/metabolismo , Fenômenos Magnéticos , Microalgas/química , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo
14.
Environ Monit Assess ; 192(2): 94, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31907685

RESUMO

A multimetric water quality standards (WQS) attainment indicator (MMI) was created to assess the habitat quality of the Chesapeake Bay and its tidal tributaries. The indicator uses metrics of dissolved oxygen concentrations, water clarity assessments, underwater bay grass acreages, and season-specific chlorophyll a distributions. This suite of metrics is recognized as symptomatic of eutrophication and responsive to nutrient and sediment management actions. Habitat criteria for these metrics were established by the US Environmental Protection Agency (USEPA) to protect the survival, growth, and reproduction of tidal bay living resources. The criteria were adopted into state WQS used to define outcome targets of the regulatory 2010 Chesapeake Bay Total Maximum Daily Load (TMDL). Direct accounting of monitoring results compared with state standards would be the most direct measure of water quality status related to achieving habitat health goal conditions under the TMDL. However, the Chesapeake Bay Program long-term water quality monitoring program that supports Clean Water Act 303d water quality impairment assessments does not provide sufficient measurement resolution across all temporal scales represented in these TMDL-related WQS. Recognizing data and analysis gaps, we developed the indicator to provide estimates of WQS attainment for the Chesapeake Bay. The structure of the indicator uses metrics that have been measured consistently with the historical Chesapeake Bay tidal water quality data collections since 1985. The ability to compute scores on contemporary and historical data will provide for bay-wide and spatially explicit long-term trend evaluations of habitat quality.


Assuntos
Baías/química , Monitoramento Ambiental/métodos , Qualidade da Água/normas , Clorofila A/análise , Ecossistema , Eutrofização/fisiologia , Oxigênio/análise , Estados Unidos , United States Environmental Protection Agency
15.
Ann Rev Mar Sci ; 12: 23-48, 2020 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-31433959

RESUMO

Biogeochemical-Argo (BGC-Argo) is a network of profiling floats carrying sensors that enable observation of as many as six essential biogeochemical and bio-optical variables: oxygen, nitrate, pH, chlorophyll a, suspended particles, and downwelling irradiance. This sensor network represents today's most promising strategy for collecting temporally and vertically resolved observations of biogeochemical properties throughout the ocean. All data are freely available within 24 hours of transmission. These data fill large gaps in ocean-observing systems and support three ambitions: gaining a better understanding of biogeochemical processes (e.g., the biological carbon pump and air-sea CO2 exchanges) and evaluating ongoing changes resulting from increasing anthropogenic pressure (e.g., acidification and deoxygenation); managing the ocean (e.g., improving the global carbon budget and developing sustainable fisheries); and carrying out exploration for potential discoveries. The BGC-Argo network has already delivered extensive high-quality global data sets that have resulted in unique scientific outcomes from regional to global scales. With the proposed expansion of BGC-Argo in the near future, this network has the potential to become a pivotal observation system that links satellite and ship-based observations in a transformative manner.


Assuntos
Monitoramento Ambiental/instrumentação , Tecnologia de Sensoriamento Remoto/métodos , Água do Mar/química , Bioquímica , Técnicas Biossensoriais/instrumentação , Clorofila A/análise , Concentração de Íons de Hidrogênio , Nitratos/análise , Oceanos e Mares , Oxigênio/análise
16.
Physiol Plant ; 168(2): 345-360, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31343742

RESUMO

We conducted a study to evaluate the interactive effect of NO and H2 S on the cadmium (Cd) tolerance of wheat. Cadmium stress considerably reduced total dry weight, chlorophyll a and b content and ratio of Fv/Fm by 36.7, 48.6, 26.7 and 19.5%, respectively, but significantly enhanced the levels of hydrogen peroxide (H2 O2 ) and malondialdehyde (MDA), endogenous H2 S and NO, and the activities of antioxidant enzymes. Exogenously applied sodium nitroprusside (SNP) and sodium hydrosulfide (NaHS), donors of NO and H2 S, respectively, enhanced total plant dry matter by 47.8 and 39.1%, chlorophyll a by 92.3 and 61.5%, chlorophyll b content by 29.1 and 27.2%, Fv/Fm ratio by 19.7 and 15.2%, respectively, and the activities of antioxidant enzymes, but lowered oxidative stress and proline content in Cd-stressed wheat plants. NaHS and SNP also considerably limited both the uptake and translocation of Cd, thereby improving the levels of some key mineral nutrients in the plants. Enhanced levels of NO and H2 S induced by NaHS were reversed by hypotuarine application, but they were substantially reduced almost to 50% by cPTIO (a NO scavenger) application. Hypotuarine was not effective, but cPTIO was highly effective in reducing the levels of NO and H2 S produced by SNP in the roots of Cd-stressed plants. The results showed that interactive effect of NO and H2 S can considerably improve plant resistance against Cd toxicity by reducing oxidative stress and uptake of Cd in plants as well as by enhancing antioxidative defence system and uptake of some essential mineral nutrients.


Assuntos
Antioxidantes/fisiologia , Cádmio/toxicidade , Sulfeto de Hidrogênio/farmacologia , Óxido Nítrico/farmacologia , Estresse Oxidativo , Triticum/efeitos dos fármacos , Clorofila A/análise , Peróxido de Hidrogênio/análise , Malondialdeído/análise , Triticum/fisiologia
17.
Lett Appl Microbiol ; 70(2): 79-86, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31677281

RESUMO

The study of interactions between beneficial micro-organisms associated with plant roots is important, because such interactions might either enhance or inhibit the beneficial effects of individual species. The effect of the combined inoculation of arbuscular mycorrhizal (AM) fungi and a biocontrol fungus (Trichoderma viride) on different growth parameters and chlorophyll a,b, carotenoids, total chlorophyll and total pigments of onion (Allium cepa) plants was studied under glasshouse conditions. The results proved that AM fungi and T. viride are compatible with each other and their combined use was effective not only in improving onion growth parameters such as fresh and dry weights, root and shoot lengths and leaf area but also increasing total chlorophyll, carotenoids and total pigments content in onion leaves. Where, inoculation of onion plants by AM fungi and T. viride alone or in combination significantly increased bulb diameters of onion plants 20, 12·5 and 17·5% increase; respectively, when compared with control ones. Also percentage of AM fungal colonization increased greatly with T. viride inoculation. Therefore, AM fungi and T. viride could be a good alternate of chemical fertilizer for improving the growth of onion. SIGNIFICANCE AND IMPACT OF THE STUDY: Significance and Impact of the Study: The need for increasing agricultural productivity and quality has led to an excessive use of chemical fertilizers; creating serious threats to human health and the environment. The use of biofertilizers is an alternative for sustaining high production with low ecological impact. Thus the goal of this study was to propose a biological technique using arbuscular mycorrhizal symbiosis and Trichoderma viride (plant-microbe interaction) for increasing plant growth that represent a great opportunities for recent agricultural practices. This may be an indication displaying the AM and Trichoderma significance for plant progress and growth.


Assuntos
Interações entre Hospedeiro e Microrganismos/fisiologia , Micorrizas/fisiologia , Cebolas/crescimento & desenvolvimento , Cebolas/fisiologia , Trichoderma/fisiologia , Clorofila A/análise , Fertilizantes , Cebolas/microbiologia , Pigmentação/fisiologia , Pigmentos Biológicos/análise , Desenvolvimento Vegetal/fisiologia , Folhas de Planta/fisiologia , Raízes de Plantas/microbiologia , Simbiose
18.
Sci Total Environ ; 708: 134833, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31796276

RESUMO

The spatial variation of chlorophyll a in the Southern Ocean (SO) was of great significance. Sea surface chlorophyll a concentrations was measured by Ferry Box monitoring system on the Chinese polar research vessel Xue Long, which circumnavigated the Antarctic continent in a clockwise direction during the austral summer 2013-2014 (November 2013-April 2014). The concentrations of chlorophyll a indicated a relatively uniform distribution of 0.049-11.647 mg m-3 (mean 0. 869 mg m-3, n = 152,751). The highest chlorophyll a concentrations (mean 1.847 mg m-3) was found in the Ross sea (RS). In addition, six high-chlorophyll a hot spots were recognized. Analysis revealed that phytoplankton bloom could be controlled by multiple factors in different regions, and the chlorophyll a bloom is attributed to the combined effect of surface and subsurface processes such as, continental shelf, sea ice melting, Circumpolar Deep Water (CDW) upwelling, suitabletemperature, and nutrient injection from subsurface to the surface. The topographic effects, sea ice melting and CDW upwelling may play a major role in controlling primary productivity in the SO. Among of all, CDW upwelling may be the most important role improving primary productivity. This study presented the phytoplankton distribution patterns and the relation with potential growth-controlling factors in the SO, which will provide more insight in the mechanisms that control global warming to reduce global CO2 the atmosphere into the ocean interior.


Assuntos
Clorofila A/análise , Regiões Antárticas , Clorofila , Oceanos e Mares , Fitoplâncton , Estações do Ano
19.
Sci Total Environ ; 704: 135269, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31796282

RESUMO

Low underwater light availability and benthivorous fish-mediated disturbance are two important factors that influence the growth of submersed macrophytes. However, the combined effects of these factors remain unclear. To determine the combined effects of low light and fish-mediated disturbance on the growth of two submersed macrophytes with contrasting growth forms, i.e., Vallisneria natans and Hydrilla verticillata, we conducted an outdoor mesocosm experiment with a two-by-two factorial design. The experiment involved two fish-mediated disturbance levels (0 and 1 Misgurnus anguillicaudatus) crossed with two levels of light intensity (ambient light and a low-light environment created by culturing the macrophytes under a shelter). The results showed that the chlorophyll a (chl a) concentration in the overlying water showed no difference among treatments for each macrophyte species. The fish-mediated disturbance significantly decreased the relative growth rate (RGR) of both species in the low-light environment but showed no effects in the ambient light environment. Low light availability and/or fish-mediated disturbance led to increased plant heights of both species compared with the heights under the ambient light regime. Low light availability combined with fish-mediated disturbance significantly reduced the ramet number and soluble carbohydrate (SC) content of both species; however, the free amino acid (FAA) content was not affected. Compared to V. natans, H. verticillata exhibited a high RGR and high ramet numbers in a low-light environment combined with fish-mediated disturbance. Our results indicated that the adaptability of H. verticillata is better than that of V. natans in turbid, shallow and hydrostatic water. Fish-mediated disturbance can negatively influence submersed macrophyte recovery in lakes when light is not abundant.


Assuntos
Clorofila A/análise , Peixes/fisiologia , Hydrocharitaceae/fisiologia , Animais , Lagos , Nitrogênio , Fósforo , Luz Solar
20.
J Plant Physiol ; 245: 153095, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31877472

RESUMO

Previous work showed in tomato plants harbouring the Agrobacterium rhizogenes rolB gene overexpression of genes involved in chloroplast function and stress response, significant increase in non-photochemical quenching and chlorophyll a and b content, and reduced chlorophyll a/b ratio. The latter condition being typical of plant shade where far-red is dominant, suggested a role for rolB in improving photosynthesis in such condition. To gain a better insight into these results, the photosynthetic performance of transgenic and control plants was compared by means of variable fluorescence kinetics with a WATER-PAM chlorophyll fluorometer, after 6 days-exposure to white light and to a far-red-enriched light source. Photosynthetic parameters analysed were quantum yield of photosystem II photochemistry Y(II); qL, corresponding to the fraction of open PSII reaction centers in a "lake" model of photosystem II; non-photochemical quenching and Y(NO), describing, respectively, regulated and non-regulated pathways for dissipation of excess energy. Chlorophyll a and b content was also analysed by HPLC. Finally, real-time PCR was performed to quantify the expression level of some of the chloroplast-related genes already shown to be overexpressed in transgenic plants. Quantum yield of photosystem II photochemistry decreased with increasing light intensity, showing no significant differences in both plant genotypes and light regimen. qL, on the other hand, was significantly higher at low PAR intensities, in particular in FR-treated transgenic plants. Fate of remaining light energy, channelled into regulated or non-regulated dissipation pathways, was different in transgenic and control plants, indicating a higher capability for protection from photodamage in rolB plants, particularly after exposure to far-red-enriched light. Chlorophyll a/b ratio was also decreased in transgenic plants under far-red-enriched light with respect to white light. Finally, qPCR showed that the expression of genes encoding small heat shock protein, chlorophyll a/b binding protein and carbonic anhydrase was significantly induced by far-red-enriched condition. Taken together, these data suggest the involvement of rolB in photosynthesis modulation under far-red-rich light in tomato.


Assuntos
Agrobacterium/genética , Proteínas de Bactérias/metabolismo , Clorofila A/metabolismo , Clorofila/metabolismo , Lycopersicon esculentum/metabolismo , Fotossíntese/efeitos da radiação , Plantas Geneticamente Modificadas/metabolismo , beta-Glucosidase/metabolismo , Proteínas de Bactérias/genética , Clorofila/análise , Clorofila A/análise , Expressão Gênica/genética , Regulação da Expressão Gênica de Plantas/genética , Proteínas de Choque Térmico Pequenas/genética , Proteínas de Choque Térmico Pequenas/metabolismo , Luz , Lycopersicon esculentum/genética , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , beta-Glucosidase/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...