Nutrients Load Estimation in a Regulated Streamflow Estuary: The São Francisco Estuary (NE/Brazil)

2020 ◽  
Author(s):  
Edmara Ramos Melo ◽  
Nilva Brandini ◽  
Paulo Ricardo Petter Medeiros ◽  
Rosiberto Silva ◽  
Geórgenes Cavalcante
Keyword(s):  
River Discharge ◽  
Winter Season ◽  
Load Estimation ◽  
Internal Circulation ◽  
Estuary Mouth ◽  
Strong Current ◽  
Nutrients Concentration ◽  
High Precipitation ◽  
Nutrients Fluxes

Abstract This study aimed to estimate the nutrients concentration variability in the São Francisco estuary from observed data during the summer and winter seasons of 2014 and to assess the influence of outflow discharges, circulation and precipitation on nutrients fluxes exchange. The marginal difference in the streamflow (1,160 m3/s - summer; 1,260 m3/s - winter) reflected the small role of the river discharge on the variability of the nutrients load. The increase in the sediments load from February (13189.70 T/month) to July (36088.56 T/month) revealed that high precipitation (153.6 mm - winter; 37.6 mm - summer) and internal circulation might have contributed to enhancing the sediment budge towards the estuary mouth. The strong current velocity in July (~0.9 m/s) revealed more potential to export estuarine waters towards the coast when compared to ~0.7 m/s (February). The concentrations and nutrients load were higher during the winter season led by phosphate (3.70 μgL-1) and NID (83.64 μg L-1), against (1.38 μgL-1 and 30.70 μgL-1 - summer), except for silicates with 4.20 mgL-1 (summer) and 3.59 mgL-1 (winter). Despite the active control of outflows, the internal circulation, followed by local precipitation, are considered the main mechanisms behind the increased nutrients load within the estuary.

The role of tides, river discharge and wind on the residual circulation of Maputo Bay

2020 ◽  
pp. 101604
Author(s):  
Paulo J. Sigaúque ◽  
Carlos A.F. Schettini ◽  
Samuel S. Valentim ◽  
Eduardo Siegle
Keyword(s):  
River Discharge ◽  
Residual Circulation

Climate as the great equalizer of continental-scale erosion

2021 ◽  
Author(s):  
Gilby Jepson ◽  
Barbara Carrapa ◽  
Jack Gillespie ◽  
Ran Feng ◽  
Peter DeCelles ◽  
...  
Keyword(s):  
Central Asia ◽  
Regional Scale ◽  
Continental Scale ◽  
Active Tectonic ◽  
Tectonically Active ◽  
High Precipitation ◽  
Tectonic Boundaries ◽  
Great Equalizer ◽  
Tian Shan

<p>Central Asia is one of the most tectonically active and orographically diverse regions in the world and is the location of the highest topography on Earth resulting from major plate tectonic collisional events. Yet the role of tectonics versus climate on erosion remains one of the greatest debates of our time. We present the first regional scale analysis of 2526 published low-temperature thermochronometric dates from Central Asia spanning the Altai-Sayan, Tian Shan, Tibet, Pamir, and Himalaya. We compare these dates to tectonic processes (proximity to tectonic boundaries, crustal thickness, seismicity) and state-of-the-art paleoclimate simulations in order to constrain the relative influences of climate and tectonics on the topographic architecture and erosion of Central Asia. Predominance of pre-Cenozoic ages in much of the interior of central Asia suggests that significant topography was created prior to the India-Eurasia collision and implies limited subsequent erosion. Increasingly young cooling ages are associated with increasing proximity to active tectonic boundaries, suggesting a first-order control of tectonics on erosion. However, areas that have been sheltered from significant precipitation for extensive periods of time retain old cooling ages. This suggests that ultimately climate is the great equalizer of erosion. Climate plays a key role by enhancing erosion in areas with developed topography and high precipitation such as the Tian Shan and Altai-Sayan during the Mesozoic and the Himalaya during the Cenozoic. Older thermochronometric dates are associated with sustained aridity following more humid periods.</p>

scholarly journals A Study on Role of Fluctuation in River Discharge in Forming River Environment

1998 ◽  
Vol 26 ◽  
pp. 77-84
Author(s):  
Minoru YASUDA ◽  
Yasuo SHIMIZU ◽  
Takayuki TAKEMOTO
Keyword(s):  
River Discharge

scholarly journals Multi-Decadal Trends and Variability in Temperature and Salinity in the Mid-Atlantic Bight, Georges Bank, and Gulf of Maine

2018 ◽  
Vol 76 (5) ◽  
pp. 163-215 ◽  
Author(s):  
Elizabeth J. Wallace ◽  
Lev B. Looney ◽  
Donglai Gong
Keyword(s):  
River Discharge ◽  
Gulf Of Maine ◽  
Winter Season ◽  
Hudson River ◽  
The Other ◽  
Georges Bank ◽  
Spring Season ◽  
Science Center ◽  
Other Hand ◽  
Decadal Scale

Increasing attention is being placed on the regional impact of climate change. This study focuses on the decadal scale variabilities of temperature and salinity in the Mid-Atlantic Bight (MAB), Georges Bank (GB), and Gulf of Maine (GOM) from 1977 to 2016 using hydrographic survey data from the National Oceanic and Atmospheric Administration (NOAA) Northeast Fisheries Science Center. The MAB (as defined by the shelf regions from Cape Hatteras to Cape Cod) experienced warming rates of 0.57 °C per decade during the Winter/Spring season (Jan–Apr) and 0.47 °C per decade during the Fall/Winter season (Sep–Dec). The GOM and GB, on the other hand, warmed at approximately half the rate of the MAB over the same time span (1977–2016). We found that rates of warming vary on decadal time scales. From 1977 to 1999, significant temperature increases (> 0.6 °C/decade) were found in the southern regions of the MAB during the Winter/Spring season. During the same period, significant freshening (stronger than– 0.2/decade) was found in GB and the northern regions of the MAB during the Winter/Spring and Summer seasons. From 1999 to 2016, on the other hand, we found no significant trends in temperature and few significant trends in salinity with the exceptions of some northern MAB regions showing significant salting. Interannual variability in shelf salinity can in part be attributed to river discharge variability in the Hudson River and Chesapeake Bay. However, decadal scale change in shelf salinity cannot be attributed to changes in river discharge as there were no significant decadal scale changes in river outflow. Variability in along-shelf freshwater transport and saline intrusions from offshore were the likely drivers of long-term changes in MAB shelf-salinity.

scholarly journals Study of episootic sıtuation at poultry farms for colibacteriosis and salmonellosis in Azerbaijan

2021 ◽  
Vol 23 (103) ◽  
pp. 56-59
Author(s):  
S. B. Abbasov
Keyword(s):  
Research Work ◽  
Winter Season ◽  
Winter Period ◽  
Bacteriological Examination ◽  
Spring Season ◽  
Autumn Period ◽  
E Coli ◽  
Poultry Farms ◽  
The Republic

The article refers to the research work carried out in recent years at the poultry farms of the Khachmaz region of the Republic of Azerbaijan, the influence of opportunistic microbes on the activities of the farm. The role of opportunistic microbes in the occurrence of certain diseases with deficiencies in the process of feeding and raising of birds, and the microclimate in poultry farms is shown. During the bacteriological examination of breeding eggs by seasons there were revealed the presence of infection in the winter season with E. coli, Salmonella, Staphylococcus and Streptococcus – with each infection separately 13.0 %, in the spring season with E. coli, Salmonella, Staphylococcus – with each infection separately 20.0 %, in the autumn period with E. coli 27.0%, Salmonella 40.0 %, Staphylococcus 13.0 % and Streptococcus 13.0 %. In the course of bacteriological examination of dead embryos, the presence of infection in the winter period with E. coli 20.0 %, salmonella 30.0 %, staphylococcus 25.0 % and streptococcus 25.0 %, in the spring  season with E. coli 30.0 %, salmonella 40.0 %, staphylococcus 15.0 % and streptococcus 15.0 %, in the autumn season with E. coli 45.0 %, salmonella 55.0 % was revealed. In the autumn period, infection with staphylococci and streptococci was not detected. When studying as a whole, pseudomoniasis and mold fungi were not found.

scholarly journals Diatom Biodiversity in Karst Springs of Mediterranean Geographic Areas with Contrasting Characteristics: Islands vs Mainland

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2602 ◽  
Author(s):  
Giuseppina G. Lai ◽  
Sara Burato ◽  
Bachisio M. Padedda ◽  
Raffaella Zorza ◽  
Elisabetta Pizzul ◽  
...  
Keyword(s):  
Anthropogenic Impact ◽  
Multivariate Analyses ◽  
Winter Season ◽  
Global Scale ◽  
Diatom Assemblages ◽  
Karst Springs ◽  
Karst Ecosystems ◽  
Structural Indices ◽  
Epilithic Diatom

Karst ecosystems are considered as priority environments for the protection of biodiversity on a global scale. This study provides a first comparative analysis of epilithic diatom flora from karst springs in two Mediterranean geographic areas (Spain and Italy) with contrasting characteristics (islands vs mainland). We investigated twenty-three springs with different anthropogenic impact levels once in the winter season between 2007 and 2017 (N = 23). A total of 176 diatom taxa (56 genera) were found of which 101 (44 genera) were observed in single sites. A general good biotic integrity was revealed by structural indices (species richness, diversity and evenness). However, crenophilous species were generally present and abundant in less impacted springs. Comparing islands and mainland, significant differences were found in species composition and diversity (H’) based on multivariate analyses (global R = 0.610; p = 0.001) and t-test (t = 2.304; p = 0.031). Discharge and Cl− were the most significant variables in determining diatom assemblages. Our results confirm the role of springs as multiple ecotones and refuges for rare species and suggest that the geographic insularity may be an important factor in maintaining diatom biodiversity.

scholarly journals Time Evolution of Estuarine Turbidity Maxima in Well-Mixed, Tidally Dominated Estuaries: The Role of Availability- and Erosion-Limited Conditions

2018 ◽  
Vol 48 (8) ◽  
pp. 1629-1650 ◽  
Author(s):  
Ronald L. Brouwer ◽  
George P. Schramkowski ◽  
Yoeri M. Dijkstra ◽  
Henk M. Schuttelaars
Keyword(s):  
River Discharge ◽  
Suspended Sediment Concentration ◽  
Time Lag ◽  
Sediment Concentration ◽  
Fine Sediment ◽  
Time Varying ◽  
Hydrodynamic Conditions ◽  
Good Qualitative Agreement ◽  
Estuarine Turbidity Maxima

AbstractUsing an idealized width-averaged process-based model, the role of a mud pool on the bed and time-varying river discharge on the trapping of fine sediment is systematically investigated. For this purpose, a dynamically and physically motivated description of erodibility is presented, which relates the amount of sediment on the bed to the suspended sediment concentration (SSC). We can distinguish between two states: in the availability-limited state, the SSC is limited by the amount of erodible sediment at the bed. Over time, under constant forcing conditions, the estuary evolves to morphodynamic equilibrium. In the erosion-limited state, there is an abundant amount of sediment at the bed so that sediment pickup occurs at the maximum possible rate. The SSC is then limited by the local hydrodynamic conditions. In this state, the estuary keeps importing sediment, forming an erodible bottom pool that grows in time. These two states can be used to explain the response of an estuary to changing river discharge. Under availability-limited conditions, periods of high river discharge push estuarine turbidity maxima (ETMs) downstream, while drier periods allow ETMs to move upstream. However, when the estuary is in an erosion-limited state during low river discharge, a bottom pool is formed. When the discharge then increases, it takes time to deplete this pool, so that an ETM located over a bottom pool moves with a significant time lag relative to changes in the river discharge. Good qualitative agreement is found between model results and observations in the Scheldt Estuary of surface SSC using a representative year of discharge conditions.

A seasonal tropical sink for atmospheric CO2 in the Atlantic ocean: the role of the Amazon River discharge

2000 ◽  
Vol 68 (3) ◽  
pp. 183-201 ◽  
Author(s):  
J.F Ternon ◽  
C Oudot ◽  
A Dessier ◽  
D Diverres
Keyword(s):  
Atlantic Ocean ◽  
River Discharge ◽  
Atmospheric Co2 ◽  
Amazon River

scholarly journals Vapor isotopic evidence for the worsening of winter air quality by anthropogenic combustion-derived water

2020 ◽  
Vol 117 (52) ◽  
pp. 33005-33010
Author(s):  
Meng Xing ◽  
Weiguo Liu ◽  
Xia Li ◽  
Weijian Zhou ◽  
Qiyuan Wang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Air Quality ◽  
Relative Humidity ◽  
Isotope Composition ◽  
Winter Season ◽  
Energy Structure ◽  
Particulate Pollution ◽  
Guanzhong Basin ◽  
Physical And Chemical

Anthropogenic combustion-derived water (CDW) may accumulate in an airshed due to stagnant air, which may further enhance the formation of secondary aerosols and worsen air quality. Here we collected three-winter-season, hourly resolution, water-vapor stable H and O isotope compositions together with atmospheric physical and chemical data from the city of Xi’an, located in the Guanzhong Basin (GZB) in northwestern China, to elucidate the role of CDW in particulate pollution. Based on our experimentally determined water vapor isotope composition of the CDW for individual and weighted fuels in the basin, we found that CDW constitutes 6.2% of the atmospheric moisture on average and its fraction is positively correlated with [PM2.5] (concentration of particulate matter with an aerodynamic diameter less than 2.5 μm) as well as relative humidity during the periods of rising [PM2.5]. Our modeling results showed that CDW added additional average 4.6 μg m−3 PM2.5 during severely polluted conditions in the GZB, which corresponded to an average 5.1% of local anthropogenic [PM2.5] (average at ∼91.0 μg m−3). Our result is consistent with the proposed positive feedback between the relative humidity and a moisture sensitive air-pollution condition, alerting to the nontrivial role of CDW when considering change of energy structure such as a massive coal-to-gas switch in household heating in winter.

scholarly journals Conditions of spatiotemporal variability of the thickness of the ice cover on lakes in the Tatra Mountains

2020 ◽  
Vol 17 (10) ◽  
pp. 2369-2386
Author(s):  
Maksymilian Solarski ◽  
Mirosław Szumny
Keyword(s):  
Snow Cover ◽  
Winter Season ◽  
Ice Cover ◽  
Spatiotemporal Variability ◽  
Ice Thickness ◽  
Tatra Mountains ◽  
Cover Thickness ◽  
The Tatra Mountains ◽  
The Impact

Abstract This research aimed to identify the impact of local climatic and topographic conditions on the formation and development of the ice cover in high-mountain lakes and the representativeness assessment of periodic point measurements of the ice cover thickness by taking into consideration the role of the avalanches on the icing of the lakes. Field works included measurement of the ice and snow cover thickness of seven lakes situated in the Tatra Mountains (UNESCO biosphere reserve) at the beginning and the end of the 2017/2018 winter season. In addition, morphometric, topographic and daily meteorological data of lakes from local IMGW (Polish Institute of Meteorology and Water Management) stations and satellite images were used. The obtained results enabled us to quantify the impact of the winter eolian snow accumulation on the variation in ice thickness. This variation was ranging from several centimetres up to about 2 meters and had a tendency to increase during the winter season. The thickest ice covers occurred in the most shaded places in the direct vicinity of rock walls. The obtained results confirm a dominating role of the snow cover in the variation of the ice thickness within individual lakes.

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