Depth is Relative: The Importance of Depth on TEP in the Near Surface Environment

Abstract. Transparent exopolymer particles (TEP) are a major source for both organic matter (OM) and carbon transfer in the ocean and into the atmosphere. Consequently, understanding the vertical distribution of TEP and the processes which impact its movement are important in understanding the OM and carbon pools on a larger scale. Additionally, most studies looking at the vertical profile of TEP have focused on large depth scales from 5 to 1000s meters and have omitted the near surface environment. Results from a study of TEP enrichment in the sea surface microlayer (SML) in different regions (tropical, temperate) has shown that while there is a correlation between TEP abundance and primary production (PP) on larger or seasonal scales, such relationships break down on shorter time and spatial scales. Using a novel small-scale vertical sampler, the vertical distribution of TEP within the uppermost 2 meters was investigated. With a maximum variance of TEP abundance between depths (1.39 × 106 µg XG eq2 L-2) and a minimum variance of (6 × 102 µg XG eq2 L-2) the vertical distribution of TEP was found to be both heterogeneous and homogeneous at times. Results from the enrichment of TEP and Chl a between different regions has shown TEP enrichment to be greater in oligotrophic waters, when both Chl a and TEP abundance was low, suggesting the importance of abiotic sources for the enrichment of TEP in the SML. However, considering multiple additional parameters that were sampled, it is clear that no single parameter could be used as a proxy for TEP heterogeneity, other probable biochemical drivers of TEP transport are discussed.

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Depth is relative: the importance of depth for transparent exopolymer particles in the near-surface environment

Ocean Science ◽

10.5194/os-15-1653-2019 ◽

2019 ◽

Vol 15 (6) ◽

pp. 1653-1666 ◽

Cited By ~ 2

Author(s):

Tiera-Brandy Robinson ◽

Christian Stolle ◽

Oliver Wurl

Keyword(s):

Vertical Distribution ◽

Small Scale ◽

Surface Microlayer ◽

Transparent Exopolymer Particles ◽

Near Surface ◽

Chl A ◽

Sea Surface Microlayer ◽

Carbon Transfer ◽

The Vertical Distribution ◽

Surface Environment

Abstract. Transparent exopolymer particles (TEPs) are a major source for both organic matter (OM) and carbon transfer in the ocean and into the atmosphere. Consequently, understanding the vertical distribution of TEPs and the processes which impact their movement is important in understanding the OM and carbon pools on a larger scale. Additionally, most studies looking at the vertical profile of TEPs have focused on large depth scales from 5 to 1000 m and have omitted the near-surface environment. Results from a study of TEP enrichment in the sea surface microlayer (SML) in different regions (tropical, temperate) has shown that, while there is a correlation between TEP concentration and primary production (PP) on larger or seasonal scales, such relationships break down on shorter timescales and spatial scales. Using a novel small-scale vertical sampler, the vertical distribution of TEPs within the uppermost 2 m was investigated. For two regions with a total of 20 depth profiles, a maximum variance of TEP concentration of 1.39×106 µg XG eq2 L−2 between depths and a minimum variance of 6×102 µg XG eq2 L−2 was found. This shows that the vertical distribution of TEPs was both heterogeneous and homogeneous at times. Results from the enrichment of TEPs and Chl a between different regions have shown TEP enrichment in the SML to be greater in oligotrophic waters, when both Chl a and TEP concentrations were low, suggesting the importance of abiotic sources for the enrichment of TEPs in the SML. However, considering multiple additional parameters that were sampled, it is clear that no single parameter could be used as a proxy for TEP heterogeneity. Other probable biochemical drivers of TEP transport are discussed.

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Vertical Distribution of Particulates within the Near-Surface Layer of Dry Bulk Port and Influence Mechanism: A Case Study in China

Sustainability ◽

10.3390/su11247135 ◽

2019 ◽

Vol 11 (24) ◽

pp. 7135 ◽

Cited By ~ 2

Author(s):

Jinxing Shen ◽

Xuejun Feng ◽

Kai Zhuang ◽

Tong Lin ◽

Yan Zhang ◽

...

Keyword(s):

Vertical Distribution ◽

Weather Conditions ◽

Dust Suppression ◽

Near Surface ◽

Cargo Handling ◽

Port Operation ◽

Pm10 And Pm2.5 ◽

The Impact ◽

The Vertical Distribution ◽

Porous Fence

Knowing the vertical distribution of ambient particulate matter (PM) will help port authorities choose the optimal dust-suppression measures to reduce PM concentrations. In this study, we used an unmanned aerial vehicle (UAV) to assess the vertical distribution (0–120 m altitude) of PM in a dry bulk port along the Yangtze River, China. Total suspended particulates (TSP), PM10, and PM2.5 concentrations at different altitudes were measured at seven sites representing different cargo-handling sites and a background site. Variations in results across sites make it not suitable to characterize the vertical distribution of PM concentration at this port using simple representative distributions. Bulk cargo particle size, fog cannon use, and porous fence all affected the vertical distribution of TSP concentrations but had only minor impacts on PM10 and PM2.5 concentrations. Optimizing porous fence layout according to weather conditions and cargo demand at port have the most potential for mitigating PM pollution related to port operation. As ground-based stations cannot fully measure vertical PM distributions, our methods and results represent an advance in assessing the impact of port activities on air quality and can be used to determine optimal dust-suppression measures for dry bulk ports.

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Sinking microplastics in the water column: simulations in the Mediterranean Sea

Ocean Science ◽

10.5194/os-17-431-2021 ◽

2021 ◽

Vol 17 (2) ◽

pp. 431-453

Author(s):

Rebeca de la Fuente ◽

Gábor Drótos ◽

Emilio Hernández-García ◽

Cristóbal López ◽

Erik van Sebille

Keyword(s):

Vertical Distribution ◽

Mediterranean Sea ◽

Water Column ◽

Large Scale ◽

Circulation Model ◽

Small Scale ◽

The Mediterranean ◽

Scale Turbulence ◽

Non Gaussian ◽

The Vertical Distribution

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects (inertia, Coriolis force, small-scale turbulence and variable seawater density), and we bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

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Assessing the potential for DMS enrichment at the sea-surface and its influence on air–sea flux

10.5194/os-2016-26 ◽

2016 ◽

Author(s):

C. F. Walker ◽

M. J. Harvey ◽

M. J. Smith ◽

T. G. Bell ◽

E. S. Saltzman ◽

...

Keyword(s):

Sea Surface ◽

Gas Transfer ◽

Surface Microlayer ◽

Surface Seawater ◽

Biological Factors ◽

Near Surface ◽

Wind Speeds ◽

Factors Influencing ◽

Sea Surface Microlayer ◽

High Enrichment

Abstract. The flux of dimethylsulfide (DMS) to the atmosphere is generally inferred using water sampled at or below 2 m depth, thereby excluding any concentration anomalies at the air–sea interface. Two independent techniques were used to assess the potential for near-surface DMS enrichment to influence DMS emissions and also identify the factors influencing enrichment. DMS measurements in productive frontal waters over the Chatham Rise, east of New Zealand, did not identify any significant DMS gradients between 0.01 and 6 m in sub-surface seawater, whereas DMS enrichment in the sea-surface microlayer was variable, with a mean enrichment factor (EF; the concentration ratio between DMS in the SSM and in sub-surface water) of 1.7. Physical and biological factors influenced sea-surface microlayer DMS concentration, with high enrichment (EF > 1.3) only recorded in a dinoflagellate-dominated bloom, and associated with low to medium wind speeds and near-surface temperature gradients. On occasion, high DMS enrichment preceded periods when the air–sea DMS flux, measured by eddy covariance, exceeded the flux calculated using COARE parameterised gas transfer velocities and measured sub-surface seawater DMS concentrations. The results of these two independent approaches suggest that air–sea emissions may be influenced by near-surface DMS production under certain conditions, and highlights the need for further study to constrain the magnitude and mechanisms of DMS production in the sea surface microlayer.

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Wind Erosion at a Saline Playa Environment, Ebinur Lake, Xinjiang, China - A Case Study on the Source of Saline Dust Storm

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.260-261.1003 ◽

2012 ◽

Vol 260-261 ◽

pp. 1003-1008

Author(s):

Dong Wei Liu ◽

Jilili Abuduwaili

Keyword(s):

Vertical Distribution ◽

Wind Erosion ◽

Dust Storms ◽

Aeolian Transport ◽

Near Surface ◽

Erosion Pins ◽

Dry Lake ◽

The Vertical Distribution ◽

Main Factor

In many arid and semiarid lands, dry lake beds (saline playa) represent a tremendous source of unconsolidated salt-rich sediments that are available for aeolian transport. Severe salt-dust storms caused by the erosion of such landforms have become very harmful natural phenomena. Base on texture and appearance characteristic, five principal undisturbed playa surfaces for sampling to investigate the deflation rate and the vertical distribution of material abraded using a wind-tunnel experiment in this study. Two additional field deflation monitoring transect were aslo established to examine vertical deflation by wind from measurements of erosion pins at the Ebinur (dry) Lake. The results indicate that winds greater than 8 m/s is the main factor for inducing the erosion of the playa sediments. Soft salt, aeloian sediment and alluvial deposit are the main sources of the saline dust storms in Ebinur region. The near-surface vertical distribution of material abraded concentrated in 0 -10 cm height. The annual wind erosion rate ranged from 0.48 cm to 5.6 cm in the northwest portion of the lake and from 0.24 cm to 0.96 cm in the southeast portion.

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Characterizing the surface microlayer in the Mediterranean Sea: trace metal concentrations and microbial plankton abundance

Biogeosciences ◽

10.5194/bg-17-2349-2020 ◽

2020 ◽

Vol 17 (8) ◽

pp. 2349-2364 ◽

Cited By ~ 3

Author(s):

Antonio Tovar-Sánchez ◽

Araceli Rodríguez-Romero ◽

Anja Engel ◽

Birthe Zäncker ◽

Franck Fu ◽

...

Keyword(s):

Mediterranean Sea ◽

Negative Correlation ◽

Salinity Gradient ◽

Western Mediterranean ◽

Surface Microlayer ◽

Dissolved Metals ◽

Strong Negative Correlation ◽

Chl A ◽

Sea Surface Microlayer ◽

The Mediterranean

Abstract. The Sea Surface Microlayer (SML) is known to be enriched by trace metals relative to the underlying water and harbor diverse microbial communities (i.e., neuston). However, the processes linking metals and biota in the SML are not yet fully understood. The metal (Cd, Co, Cu, Fe, Ni, Mo, V, Zn and Pb) concentrations in aerosol samples in the SML (dissolved and total fractions) and in subsurface waters (SSWs; dissolved fraction at ∼1 m depth) from the western Mediterranean Sea were analyzed in this study during a cruise in May–June 2017. The composition and abundance of the bacterial community in the SML and SSW, the primary production, and Chl a in the SSW were measured simultaneously at all stations during the cruise. Residence times in the SML of metals derived from aerosol depositions were highly variable and ranged from minutes for Fe (3.6±6.0 min) to a few hours for Cu (5.8±6.2 h). Concentrations of most of the dissolved metals in both the SML and SSW were positively correlated with the salinity gradient and showed the characteristic eastward increase in the surface waters of the Mediterranean Sea (MS). In contrast, the total fraction of some reactive metals in the SML (i.e., Cu, Fe, Pb and Zn) showed a negative correlation with salinity and a positive correlation with microbial abundance, which might be associated with microbial uptake. Our results show a strong negative correlation between the dissolved and total Ni concentration and heterotrophic bacterial abundance in the SML and SSW, but we cannot ascertain whether this correlation reflects a toxicity effect or is the result of some other process.

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The vertical distribution and abundance of Chthamalus stellatus Poli and Chthamalus montagui Southward (Crustacea, Cirripedia) at two localities of the Istrian peninsula coast (North Adriatic)

Acta Adriatica ◽

10.32582/aa.58.1.6 ◽

2017 ◽

Vol 58 (1) ◽

pp. 77-88

Author(s):

Nataša Dolenc-Orbanić ◽

Claudio Battelli

Keyword(s):

Vertical Distribution ◽

Adriatic Sea ◽

Spatial Scales ◽

Tidal Range ◽

Rocky Shores ◽

Tidal Level ◽

The North ◽

Chthamalus Montagui ◽

The Vertical Distribution ◽

North Adriatic Sea

Two species of chthamalid barnacles are well established from the upper to the lower limit of the midlittoral zone on the rocky shores of the North Adriatic Sea: Chthamalus stellatus, Poli and Chthamalus montagui, Southward. The present study deals with the vertical distribution and abundance for each species at two localities of the Istrian peninsula coast (North Adriatic Sea). For this purpose chthamalid populations were monitored in 2015 along the Slovenian marine coast (Bay of Koper, Gulf of Trieste) and along the Croatian marine coast, near Rovinj (west Istrian coast), both on limestone. The main aim of the study was to establish if there was a relationship between the vertical distribution and abundance of these two species at different spatial scales: small (between sites, about 1 kilometer) and large (between localities, 10s of kilometers). The selected localities are slightly different in tidal range, in orientation and wave exposure. Three sites were randomly selected at each locality and two transects per tidal level (upper, middle and lower) were chosen on each site. The abundance of each chthamalids species in 1 dm2 plots was determined at three different tidal levels along each transect. The results indicated that the vertical distribution of C. montagui and C. stellatus was very similar between localities and even among sites, but their abundance varied. At both localities, C. montagui was more abundant in the upper and middle tidal levels, while C. stellatus was more abundant at the lower tidal level. It was also found that C. montagui was more abundant in sheltered conditions (Bay of Koper), while C. stellatus on the coast more exposed to the wave action (near Rovinj), at all tidal levels.

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On the vertical distribution of the chlorophyll <i>a</i> concentration in the Mediterranean Sea: a basin scale and seasonal approach

Biogeosciences Discussions ◽

10.5194/bgd-12-4139-2015 ◽

2015 ◽

Vol 12 (5) ◽

pp. 4139-4181 ◽

Cited By ~ 4

Author(s):

H. Lavigne ◽

F. D'Ortenzio ◽

M. Ribera D'Alcalà ◽

H. Claustre ◽

R. Sauzède ◽

...

Keyword(s):

Vertical Distribution ◽

Mediterranean Sea ◽

Global Ocean ◽

Control Procedure ◽

Chl A ◽

Basin Scale ◽

In Situ Experiments ◽

The Mediterranean ◽

The Vertical Distribution ◽

Surface Observations

Abstract. The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, which is mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles calibrated into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a dedicated quality control procedure. To ensure homogeneity between the different data sources, 65% of fluorescence profiles have been inter-calibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profile in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings on the range of [Chl a] values and on the main Mediterranean trophic regimes. It also provides new insights on the seasonal variability of the shape of the vertical [Chl a] profile, inaccessible from remote sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, suggesting thus that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] distribution in the Mediterranean Sea mimics, at smaller scales, what is observed in the Global Ocean. As already evidenced by analyzing satellite surface observations, mid-latitude and subtropical like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears characterized by patterns already observed at global scale.

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Determining the Pixel-to-Pixel Uncertainty in Satellite-Derived SST Fields

10.20944/preprints201707.0066.v1 ◽

2017 ◽

Author(s):

Fan Wu ◽

Peter Cornillon ◽

Brahim Boussidi ◽

Lei Guan

Keyword(s):

Spatial Scales ◽

Quality Data ◽

Good Measure ◽

Small Scale ◽

Infrared Sensors ◽

Near Surface ◽

Spectral Estimates ◽

Instrument Noise ◽

Along Track ◽

The Impact

The primary measure of the quality of sea surface temperature (SST) fields obtained from satellite-borne infrared sensors has been the bias and variance of matchups with co-located in-situ values. Because such matchups tend to be widely separated, these bias and variance estimates are not necessarily a good measure of small scale (several pixels) gradients in these fields because one of the primary contributors to the uncertainty in satellite retrievals is atmospheric contamination, which tends to have large spatial scales compared with the pixel separation of infrared sensors. Hence, there is not a good measure to use in selecting SST fields appropriate for the study of submesoscale processes and, in particular, of processes associated with near-surface fronts, both of which have recently seen a rapid increase in interest. In this study, two methods are examined to address this problem, one based on spectra of the SST data and the other on their variograms. To evaluate the methods, instrument noise was estimated in Level-2 VIIRS and AVHRR SST fields of the Sargasso Sea. The two methods provided very nearly identical results for AVHRR: along-scan values of approximately 0.18 K for both day and night and along-track values of 0.21 K also for day and night. By contrast, the instrument noise estimated for VIIRS varied by method, scan geometry and day-night. Specifically, daytime, along-scan (along-track), spectral estimates were found to be approximately 0.05 K (0.08 K) and the corresponding nighttime values of 0.02 K (0.03 K). Daytime estimates based on the variogram were found to be 0.08 K (0.10 K) with the corresponding nighttime values of 0.04 K (0.06 K). Taken together: AVHRR instrument noise is significantly larger than VIIRS instrument noise, along-track noise is larger than along-scan noise and daytime levels are higher than nighttime levels. Given the similarity of results and the less stringent preprocessing requirements, the variogram is the preferred method although there is a suggestion that this approach overestimates the noise for high quality data in dynamically quiet regions. Finally, simulations of the impact of noise on the determination of SST gradients show that on average the gradient magnitude for typical ocean gradients will be accurately estimated with VIIRS but substantially overestimated with AVHRR.

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Sinking microplastics in the water column: simulations in the Mediterranean Sea

10.5194/os-2020-95 ◽

2020 ◽

Author(s):

Rebeca de la Fuente ◽

Gábor Drótos ◽

Emilio Hernández García ◽

Cristóbal López ◽

Erik van Sebille

Keyword(s):

Vertical Distribution ◽

Mediterranean Sea ◽

Water Column ◽

Large Scale ◽

Circulation Model ◽

Small Scale ◽

The Mediterranean ◽

Scale Turbulence ◽

Non Gaussian ◽

The Vertical Distribution

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects: inertia, Coriolis force, small-scale turbulence and variable seawater density, and bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

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