Spatial Distribution and Activity of Microbial Extracellular Enzymes in the Water Column of the Mariana Trench

A two-dimensional multichannel seismic reflection profile acquired in the Madeira Abyssal Plain during June 2016 was used in a modeling workflow comprising seismic oceanography processing, geostatistical inversion and Bayesian classification to predict the probability of occurrence of distinct water masses. The seismic section was processed to image in detail the fine scale structure of the water column using seismic oceanography. The processing sequence was developed to preserve, as much as possible, the relative seismic amplitudes of the data and enhance the shallow structure of the water column by effectively suppressing the direct arrival. The migrated seismic oceanography section shows an eddy at the expected Mediterranean Outflow Water depths, steeply dipping reflectors, which indicate the possible presence of frontal activity or secondary dipping eddy structures, and strong horizontal reflections between intermediate water masses suggestive of double diffuse processes. We then developed and applied an iterative geostatistical seismic oceanography inversion methodology to predict the spatial distribution of temperature and salinity. Due to the lack of contemporaneous direct measurements of temperature and salinity we used a global ocean model as spatial constraint during the inversion and nearby contemporaneous ARGO data to infer the expected statistical properties of both model parameters. After the inversion, Bayesian classification was applied to all temperature and salinity models inverted during the last iteration to predict the spatial distribution of three distinct water masses. A preliminary interpretation of these probabilistic models agrees with the expected ocean dynamics of the region.

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THE DISTRIBUTION OF DISSOLVED FORMS COPPER IN THE WATER COLUMN OF THE CASPIAN SEA

Геология и геофизика Юга России ◽

10.23671/vnc.2018.4.20147 ◽

2018 ◽

Author(s):

В.В. Ковалев ◽

С.Г. Парада

Keyword(s):

Surface Layer ◽

Spatial Distribution ◽

Water Column ◽

Caspian Sea ◽

Sea Water ◽

Average Content ◽

Vital Activity ◽

The Caspian Sea ◽

Organic Complexes ◽

High Concentrations

По результатам химических анализов проб воды Северного, Среднего Каспия и, частично, Южного Каспия, отобранных по профилям из различных горизонтов водной толщи, определены содержания растворенных форм меди. Построены карты пространственного распределения этого элемента в поверхностном и наддонном водных горизонтах, а также по вертикальным разрезам водной толщи, выявлены закономерности их распространения в объеме морской воды. Установлены средние содержания растворенных форм меди в поверхностном (8,6 мкг/л) и в наддонном (9,6 мкг/л) горизонтах Каспийского моря. Выделены участки с аномально высокими (более 20 мкг/л) и аномально низкими (менее 5 мкг/л) концентрациями растворенных форм меди в них. Особенности распределения растворенных форм меди по вертикали водной толщи определяются жизнедеятельностью планктонных организмов и их отмиранием. В поверхностном слое аномально высокие концентрации меди связаны с прижизненным накоплением металла планктоном. На глубинах свыше 100 м аномально высокие ее концентрации связаны с распадом отмерших организмов и выделением меди и других металлов в виде органических комплексов According to the results of chemical analyzes of water samples from the Northern, Middle Caspian and, partially, the Southern Caspian, taken from profiles from different horizons of the water column, the contents of dissolved forms of copper were determined. Maps of the spatial distribution of this element in the surface and supra-aquatic horizons, as well as along vertical sections of the water column, have been constructed, and patterns of their distribution in the volume of sea water have been revealed. The average content of dissolved forms of copper in the surface (8.6 μg/l) and in the above bottom (9.6 μg/l) horizons of the Caspian Sea has been established. Selected areas with abnormally high (more than 20 μg/l) and abnormally low (less than 5 μg/l) concentrations of dissolved forms of copper in them. The specific features of the distribution of dissolved forms of copper along the vertical of the water column are determined by the vital activity of planktonic organisms and their death. In the surface layer, abnormally high concentrations of copper are associated with the lifetime accumulation of metal by plankton. At depths above 100 m, its abnormally high concentrations are associated with the decay of dead organisms and the release of copper and other metals in the form of organic complexes

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Relationship between spatial distribution of chaetognaths and hydrographic conditions around seamounts and islands of the tropical southwestern Atlantic

Anais da Academia Brasileira de Ciências ◽

10.1590/0001-3765201420130101 ◽

2014 ◽

Vol 86 (3) ◽

pp. 1151-1165 ◽

Cited By ~ 5

Author(s):

CHRISTIANE S. DE SOUZA ◽

JOANA A.G. LUZ ◽

PAULO O. MAFALDA JUNIOR

Keyword(s):

Spatial Distribution ◽

Water Column ◽

Water Mass ◽

South Atlantic ◽

Northeastern Brazil ◽

Southwestern Atlantic ◽

The South ◽

Water Column Stability ◽

South Atlantic Central Water ◽

Hydrographic Conditions

Relationship between spatial distribution of chaetognaths and hydrographic conditions around seamounts and islands off Northeastern Brazil were analyzed from 133 oceanographic stations during the months of January – April of 1997 and April – July of 1998. Oblique zooplankton tows, using 50 cm diameter Bongo nets with 500µm mesh with a flowmeter to determine the filtered volume, were carried out to a maximum of 200m depth. The Superficial Equatorial Water, which had a salinity > 36 PSU and temperature > 20°C, occupied the top 80 to 200m depth. Below this water mass was the South Atlantic Central Water with salinity ranging from 34.5 to 36 PSU and temperature from 6 to 20°C. The community of chaetognaths showed six species: Pterosagitta draco, Flaccisagitta enflata, Flaccisagitta hexaptera, Pseudosagitta lyra, Serratosagitta serratodentata, and Sagitta helenae. Of these species, F. enflata was the most abundant (32.05% in 1997 and 42.18% in 1998) and the most frequent (87.88% in 1997 and 95% in 1998) during both periods. A mesopelagic specie was identified (P. lyra). This specie was more abundant in 1997 (3.42%), when the upwelling was more intense. P. lyra occurred in 22% of the samples during 1997. The abundance of F. enflata, an epiplanktonic species, increased, associated with greater water-column stability.

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A Methodology for Measuring Microplastic Transport in Large or Medium Rivers

Water ◽

10.3390/w10040414 ◽

2018 ◽

Vol 10 (4) ◽

pp. 414 ◽

Cited By ~ 26

Author(s):

Marcel Liedermann ◽

Philipp Gmeiner ◽

Sebastian Pessenlehner ◽

Marlene Haimann ◽

Philipp Hohenblum ◽

...

Keyword(s):

Spatial Distribution ◽

Water Column ◽

Turbulent Mixing ◽

Suspended Sediments ◽

High Flow ◽

Danube River ◽

Long Term Effects ◽

Plastic Debris ◽

Different Depths

Plastic waste as a persistent contaminant of our environment is a matter of increasing concern due to the largely unknown long-term effects on biota. Although freshwater systems are known to be the transport paths of plastic debris to the ocean, most research has been focused on marine environments. In recent years, freshwater studies have advanced rapidly, but they rarely address the spatial distribution of plastic debris in the water column. A methodology for measuring microplastic transport at various depths that is applicable to medium and large rivers is needed. We present a new methodology offering the possibility of measuring microplastic transport at different depths of verticals that are distributed within a profile. The net-based device is robust and can be applied at high flow velocities and discharges. Nets with different sizes (41 µm, 250 µm, and 500 µm) are exposed in three different depths of the water column. The methodology was tested in the Austrian Danube River, showing a high heterogeneity of microplastic concentrations within one cross section. Due to turbulent mixing, the different densities of the polymers, aggregation, and the growth of biofilms, plastic transport cannot be limited to the surface layer of a river, and must be examined within the whole water column as for suspended sediments. These results imply that multipoint measurements are required for obtaining the spatial distribution of plastic concentration and are therefore a prerequisite for calculating the passing transport. The analysis of filtration efficiency and side-by-side measurements with different mesh sizes showed that 500 µm nets led to optimal results.

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Difference in temporal and spatial distribution pattern of cyanobacteria between the sediment and water column in Lake Chaohu

Environmental Pollution ◽

10.1016/j.envpol.2021.118163 ◽

2021 ◽

Vol 291 ◽

pp. 118163

Author(s):

Mingdong Ren ◽

Min Zhang ◽

Fan Fan ◽

Jinsheng Yang ◽

Zhen Yang ◽

...

Keyword(s):

Spatial Distribution ◽

Distribution Pattern ◽

Water Column ◽

Spatial Distribution Pattern ◽

Lake Chaohu ◽

Temporal And Spatial Distribution ◽

Temporal And Spatial

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Short-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: a <sup>13</sup>C pulse-chase experiment

Biogeosciences ◽

10.5194/bg-15-2873-2018 ◽

2018 ◽

Vol 15 (9) ◽

pp. 2873-2889 ◽

Cited By ~ 4

Author(s):

Philip M. Riekenberg ◽

Joanne M. Oakes ◽

Bradley D. Eyre

Keyword(s):

Water Column ◽

Nutrient Availability ◽

Nutrient Enrichment ◽

Extracellular Enzymes ◽

Turnover Time ◽

Ex Situ ◽

Nutrient Concentrations ◽

Organic C ◽

Storage Products

Abstract. Shallow coastal waters in many regions are subject to nutrient enrichment. Microphytobenthos (MPB) can account for much of the carbon (C) fixation in these environments, depending on the depth of the water column, but the effect of enhanced nutrient availability on the processing and fate of MPB-derived C (MPB-C) is relatively unknown. In this study, MPB was labeled (stable isotope enrichment) in situ using 13C-sodium bicarbonate. The processing and fate of the newly fixed MPB-C was then traced using ex situ incubations over 3.5 days under different concentrations of nutrients (NH4+ and PO43-: ambient, 2× ambient, 5× ambient, and 10× ambient). After 3.5 days, sediments incubated with increased nutrient concentrations (amended treatments) had increased loss of 13C from sediment organic matter (OM) as a portion of initial uptake (95 % remaining in ambient vs. 79–93 % for amended treatments) and less 13C in MPB (52 % ambient, 26–49 % amended), most likely reflecting increased turnover of MPB-derived C supporting increased production of extracellular enzymes and storage products. Loss of MPB-derived C to the water column via dissolved organic C (DOC) was minimal regardless of treatment (0.4–0.6 %). Loss due to respiration was more substantial, with effluxes of dissolved inorganic C (DIC) increasing with additional nutrient availability (4 % ambient, 6.6–19.8 % amended). These shifts resulted in a decreased turnover time for algal C (419 days ambient, 134–199 days amended). This suggests that nutrient enrichment of estuaries may ultimately lead to decreased retention of carbon within MPB-dominated sediments.

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Spatial distribution of turbulent mixing in the upper ocean of the South China Sea

Ocean Science ◽

10.5194/os-13-503-2017 ◽

2017 ◽

Vol 13 (3) ◽

pp. 503-519 ◽

Cited By ~ 7

Author(s):

Xiao-Dong Shang ◽

Chang-Rong Liang ◽

Gui-Ying Chen

Keyword(s):

Spatial Distribution ◽

South China Sea ◽

Water Column ◽

South China ◽

Turbulent Mixing ◽

Dissipation Rate ◽

Luzon Strait ◽

The West ◽

Dissipation Rates ◽

Diapycnal Diffusivity

Abstract. The spatial distribution of the dissipation rate (ε) and diapycnal diffusivity (κ) in the upper ocean of the South China Sea (SCS) is presented from a measurement program conducted from 26 April to 23 May 2010. In the vertical distribution, the dissipation rates below the surface mixed layer were predominantly high in the thermocline where shear and stratification were strong. In the regional distribution, high dissipation rates and diapycnal diffusivities were observed in the region to the west of the Luzon Strait, with an average dissipation rate and diapycnal diffusivity of 8.3  ×  10−9 W kg−1 and 2.7  ×  10−5 m2 s−1, respectively, almost 1 order of magnitude higher than those in the central and southern SCS. In the region to the west of the Luzon Strait, the water column was characterized by strong shear and weak stratification. Elevated dissipation rates (ε > 10−7 W kg−1) and diapycnal diffusivities (κ > 10−4 m2 s−1), induced by shear instability, occurred in the water column. In the central and southern SCS, the water column was characterized by strong stratification and weak shear and the turbulent mixing was weak. Internal waves and internal tides generated near the Luzon Strait are expected to make a dominant contribution to the strong turbulent mixing and shear in the region to the west of the Luzon Strait. The observed dissipation rates were found to scale positively with the shear and stratification, which were consistent with the MacKinnon–Gregg model used for the continental shelf but different from the Gregg–Henyey scaling used for the open ocean.

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