Oil Leak Detections with a Combined Telescopic Fluorescence Sensor and a Wide Band MultiBeam Sonar

2017 ◽  
Vol 2017 (1) ◽  
pp. 1559-1573
Author(s):  
Job Bello ◽  
Peter Eriksen ◽  
Pawel Pocwiardowski
Keyword(s):  
Water Column ◽  
Fluorescence Polarization ◽  
Open Water ◽  
Wide Band ◽  
Fluorescence Sensor ◽  
Multibeam Sonar ◽  
3 Dimensional ◽  
Water Testing ◽  
Test Pool ◽  
Operational Integration

ABSTRACT 2017-042: A combined telescopic fluorescence instrument and a wide band multibeam sonar (WBMS) were developed as dual sensors for detecting underwater oil leaks and plumes. The fluorescence instrument is a forward-looking fluorescence polarization instrument with motorized telescopic focusing that can detect oil at a standoff distance. The instrument responds only to materials showing fluorescence polarization, and therefore is able to distinguish oil from other fluorescing species in water. The WBMS is as an acoustic sensor that provides 2D as well as 3D topology for mapping and water column imagery. The operational integration of the two sensors result in a more definitive identification and mapping of oil in the water column co-registered in time and space. The sonar records a 3-dimensional map of a leak, and then the fluorescence sensor is use to confirm that the leak that the sonar detected is oil. A sensing scheme to integrate the operation and overlap the field of view of the 2 instruments was developed as well as the software algorithm to automate the detection process. Evaluations of the integrated sensors were done in a test pool and in open water. Testing results shows that the combined sensors are very effective in detecting and identifying oil plume in the water column.

Subglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica

2020 ◽  
Vol 32 (3) ◽  
pp. 223-237
Author(s):  
Jade P. Lawrence ◽  
Peter T. Doran ◽  
Luke A. Winslow ◽  
John C. Priscu
Keyword(s):  
Water Column ◽  
Internal Waves ◽  
Open Water ◽  
Surface Discharge ◽  
Katabatic Wind ◽  
Neutral Buoyancy ◽  
Cold Temperatures ◽  
Glacier Terminus ◽  
Wind Events ◽  
Taylor Glacier

AbstractBrine beneath Taylor Glacier has been proposed to enter the proglacial west lobe of Lake Bonney (WLB) as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the geochemistry of the water column of WLB. Year-round measurements from this study are the first to definitively identify brine intrusions from a subglacial entry point into WLB. Furthermore, we excluded input from Blood Falls by focusing on winter dynamics when the absence of an open water moat prevents surface brine entry. Due to the extremely high salinities below the chemocline in WLB, density stratification is dominated by salinity, and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude into the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. High-resolution measurements also reveal under-ice internal waves associated with katabatic wind events, a novel finding that challenges long-held assumptions about the stability of the WLB water column.

Phosphorus Budgets and Stoichiometry during the Open-Water Season in Two Unmanipulated Lakes in the Experimental Lakes Area, Northwestern Ontario

1994 ◽  
Vol 51 (12) ◽  
pp. 2739-2755 ◽  
Author(s):  
P. Campbell
Keyword(s):  
Water Column ◽  
Bottom Sediments ◽  
Open Water ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Phosphorus Budgets ◽  
Mass Balance Approach ◽  
Primary And Secondary Producers ◽  
Column Total

A comparative mass-balance approach is used to describe and quantify phosphorus (P) cycles during the open-water season in two unmanipulated Experimental Lakes Area (ELA) lakes. A bimodal cycle generally prevailed, in which water-column total phosphorus (TP = total dissolved P plus sestonic particulate P) peaked just after ice-out and again late in the summer. Changes in mass of water-column TP were often much larger than corresponding net external inputs. Shifts of P to and from either zooplankton or fish in the water column do not explain the P residuals. Rather, the bottom sediments must have been adding P to the water column. Short-term regeneration of P from the bottom sediments also probably occurs in artificially eutrophied ELA lakes. The mechanism of regeneration is probably biological. Other aspects of P cycling and P stoichiometry are discussed, particularly in relation to nutrient control of population structure and the function of primary and secondary producers.

scholarly journals Observations of Shallow Methane Bubble Emissions From Cascadia Margin

2021 ◽  
Vol 9 ◽  
Author(s):  
Anna P. M. Michel ◽  
Victoria L. Preston ◽  
Kristen E. Fauria ◽  
David P. Nicholson
Keyword(s):  
Water Column ◽  
Water Depth ◽  
Dissolved Methane ◽  
Multibeam Sonar ◽  
Surface Ocean ◽  
Transient Nature ◽  
Technological Approach ◽  
Open Questions ◽  
Cascadia Margin ◽  
Methane Bubble

Open questions exist about whether methane emitted from active seafloor seeps reaches the surface ocean to be subsequently ventilated to the atmosphere. Water depth variability, coupled with the transient nature of methane bubble plumes, adds complexity to examining these questions. Little data exist which trace methane transport from release at a seep into the water column. Here, we demonstrate a coupled technological approach for examining methane transport, combining multibeam sonar, a field-portable laser-based spectrometer, and the ChemYak, a robotic surface kayak, at two shallow (<75 m depth) seep sites on the Cascadia Margin. We demonstrate the presence of elevated methane (above the methane equilibration concentration with the atmosphere) throughout the water column. We observe areas of elevated dissolved methane at the surface, suggesting that at these shallow seep sites, methane is reaching the air-sea interface and is being emitted to the atmosphere.

Colonization by lake benthos of hard substrata in the water column versus on the bottom

1998 ◽  
Vol 49 (2) ◽  
pp. 157 ◽  
Author(s):  
G. P. Quinn ◽  
P. S. Lake ◽  
E. S. G. Schreiber
Keyword(s):  
Water Column ◽  
Benthic Macroinvertebrates ◽  
Open Water ◽  
Almost All ◽  
Benthic Animals ◽  
Hard Substrata

Little work has been done on colonization by lake benthos, particularly onto hard substrata. This study experimentally compared the rates of colonization of hard substrata (bricks) in a lake by benthic macroinvertebrates from two sources — the water column and the bottom. Colonization onto bricks (as mimics of stones) placed on the bottom of the lake was compared with colonization onto bricks suspended in the water column, where they could not be reached by crawling fauna. Almost all taxa colonizing bottom bricks also colonized suspended bricks, including taxa usually considered benthic (e.g. gastropods, mites, oligochaetes and planarians). Water-column samples confirmed the presence of these taxa in open water. These results suggest that many benthic animals in lakes may move through the water column more readily than previously considered; constant movement by lake benthos may be in response to shortage of resources.

STANDARDIZING BOOM TEST PROCEDURES1

1985 ◽  
Vol 1985 (1) ◽  
pp. 41-45
Author(s):  
M. Borst ◽  
H. W. Lichte
Keyword(s):  
Standardized Test ◽  
Extended Period ◽  
Open Water ◽  
Fold Increase ◽  
Weather Conditions ◽  
Technical Committee ◽  
Design Parameters ◽  
Sea State ◽  
Water Testing ◽  
Wide Range

ABSTRACT The Interagency Technical Committee (OITC) of the U.S. Environmental Protection Agency's (EPA) Oil and Hazardous Materials Simulated Environmental Test Tank (OHMSETT) facility sponsored a combined series of in-tank and open-water tests on five booms. The booms selected cover the wide range of sizes and design parameters often considered appropriate for spill control. The tests were conducted at the OHMSETT facility and in nearby Sandy Hook Bay between November 1983 and May 1984. The in-tank tests measured the oil-holding performance of the boom; the open-water tests demonstrated wave conformance and survivability. The objective was to correlate the two sets of data. The five in-tank tests for each boom used a standardized test matrix for oil-holding ability. Wave conformance and endurance were observed under controlled conditions. The results of this testing compared favorably with historical tests performed in the test task. The five booms were deployed in the bay over an extended period. The length of deployment varied from 14 to 27 days depending on the local weather conditions. The booms were observed and videotaped to document approximate sea-state limits of the booms. The booms deployed in the bay were approximately 500 ft long. The tank tests used 100 ft lengths. Wave conformance in the two tests was similar. The five-fold increase in boom length made any lack of conformance more obvious, however. The data derived from the open-water testing were based primarily on visual observations and sea-state estimates. The in-tank endurance tests did not correlate as well as expected with the open-water testing. Determining the deterioration of a boom during long-term deployment by in-tank testing was discounted by this program. This paper documents the results of the initial in-tank and open-water tests, emphasizing the techniques of testing, and outlines plans for the future tests.

Influence of extended water column mixing during the first 2 years of hypolimnetic oxygenation on the phytoplankton community of Amisk Lake, Alberta

1997 ◽  
Vol 54 (9) ◽  
pp. 2133-2145 ◽  
Author(s):  
D J Webb ◽  
R D Robarts ◽  
E E Prepas
Keyword(s):  
Water Column ◽  
Trophic Status ◽  
Phytoplankton Community ◽  
Euphotic Zone ◽  
Open Water ◽  
Eutrophic Lake ◽  
Cyanobacterial Blooms ◽  
Chl A ◽  
Hypolimnetic Oxygenation ◽  
Physical Variables

The phytoplankton community, physical variables, and nutrient and chlorophyll a (Chl a) concentrations were monitored during the first two of six open-water seasons of hypolimnetic oxygenation in double-basined Amisk Lake, Alberta. Deep mixing of the water column in the treated basin (Zmax = 34 m) in spring was enhanced by hypolimnetic oxygenation. Oxygenation began in June 1988, when stratification was likely already established, but subsequent year-round treatment favoured an extended spring diatom bloom (Asterionella formosa and Cyclotella spp.), followed by a delay in the development of, and reduction in the severity of, cyanobacterial blooms (Aphanizomenon flos-aquae and Anabaena flos-aquae) in 1989. Historically, mean summer Chl a and total phosphorus (TP) concentrations in the euphotic zone (0-6 m) of the treated basin were 15.9 ± 1.6 and 33.5 ± 1.5 µg ·L-1, respectively, indicating a eutrophic lake. In 1988 and 1989, mean summer Chl a (10.0 ± 0.6 and 8.1 ± 0.7 µg ·L-1, respectively) and TP concentrations (29.0 ± 0.5 and 22.5 ± 0.9 µg ·L-1, respectively) in this stratum were lower than historic values (P < 0.05), indicating that the trophic status of Amisk Lake had shifted towards mesotrophy.

Characterization of the photoautotrophic algal and bacterial communities in a large, shallow, subtropical lake using HPLC-PDA based pigment analysis

1998 ◽  
Vol 55 (1) ◽  
pp. 206-219 ◽  
Author(s):  
Alan D Steinman ◽  
Karl E Havens ◽  
J William Louda ◽  
Nancy M Winfree ◽  
Earl W Baker
Keyword(s):  
Water Column ◽  
Chlorophyll A ◽  
High Performance ◽  
Principal Component ◽  
Open Water ◽  
High Performance Liquid Chromatographic ◽  
Lake Okeechobee ◽  
Pheophytin A ◽  
Pigment Analysis ◽  
Liquid Chromatographic

Pigment abundances of the oxygenic and anoxygenic photoautotrophic communities from sediments and the water column in Lake Okeechobee, Florida, were estimated using reverse-phase high-performance liquid chromatographic (RP-HPLC) and photodiode array (PDA) UV/VIS (350-800 nm) spectrophotometric analyses. Thirty lipophilic pigments were identified and measured in the samples, with the most abundant overall (sediment and open-water samples combined) being chlorophyll a (38.1%), fucoxanthin (12.6%), pheophytin a (7.6%), zeaxanthin (6.6%), and pyropheophytin a (3.6%). Relative abundance of chlorophyll a was greater in the water column than in the sediments (58.3 versus 24.3% of all pigments) whereas pheophytin a comprised 9.1% of the total pigments in the sediments but only 3.7% of the total pigments in the water column. Principal component analysis (PCA) separated the sediment samples from those collected in the water column; this discrimination appears to be a function of pigment integrity in that sediment assemblages had much greater relative abundances of degraded pigments. Different regions of the lake were weakly separated by PCA based on pigments. The relatively weak degree of separation may reflect the overwhelming abundance of chlorophyll a at all sites. Overall, the pigment assemblage in Lake Okeechobee suggests cyanobacteria-diatom dominance. Out of 65 sampling events, pigments from anoxygenic photoautotrophs (e.g., bacteriochlorophylls) were detected 17 times but accounted for >20% of total chlorophyll only five times. Bacteriochlorophylls were observed only in the sediments and were most abundant during June and September, when winds were calm and temperatures warm, and at relatively shallow sites.

DOM DYNAMICS IN THE MEDITERRANEAN SEA. Can a new fluorescence SENSOR contribute to its understanding?

2020 ◽  
Author(s):  
Simona Retelletti Brogi ◽  
Marta Furia ◽  
Giancarlo Bachi ◽  
Vanessa Cardin ◽  
Giuseppe Civitarese ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Mediterranean Sea ◽  
Water Column ◽  
Fluorescence Sensor ◽  
Global Ocean ◽  
Intermediate Water ◽  
Physical Processes ◽  
Open Sea ◽  
The Mediterranean

&lt;p&gt;The Mediterranean Sea (Med Sea) can be considered as a natural laboratory for the study of dissolved organic matter (DOM) dynamics. Despite its small size, it is characterized by the same physical processes and dissolved organic carbon (DOC) concentration and distribution as the global ocean. The Med Sea deep water DOC pool is however older than the Atlantic one and differences in the microbial loop and in DOM dynamics have been observed between the eastern (EMED) and western (WMED) basins. Fluorescence is a fast, cheap and highly sensitive tool to study DOM dynamics, it can therefor give useful information about the main processes affecting DOM distribution.&lt;/p&gt;&lt;p&gt;The main aims of this study were: (i) to investigate DOM dynamics in both Med Sea basins, in relation to the physical processes (e.g. vertical stratification, irradiation); and (ii) to validate the use of a new fluorescence sensor, developed in the framework of the SENSOR project (POR FESR, Tuscany Region), for the rapid, in-situ measurements of open-sea fluorescent DOM (FDOM). DOM dynamics was investigated by measuring dissolved organic carbon (DOC) and the fluorescence of FDOM. Samples were collected from surface to bottom in 26 stations during the trans-Mediterranean cruise &amp;#8220;MSM72&amp;#8221;, carried out on board the R/V MARIA S.MERIAN (Institut f&amp;#252;r Meereskunde der Universit&amp;#228;t Hamburg). The stations cover both the EMED and the WMED, from Gibraltar to the Crete Island.&lt;/p&gt;&lt;p&gt;Six fluorescent components were identified by applying the parallel factorial analysis (PARAFAC) to the measured excitation-emission matrices (EEMs). Two components were identified as marine humic-like, two as terrestrial humic-like, one as protein-like and one as polycyclic aromatic hydrocarbon-like (PAH-like).&lt;/p&gt;&lt;p&gt;Temperature and salinity increased moving from the WMED to the EMED. A surface minimum in salinity, was observed in the WMED, indicating the occurrence of the Atlantic Water (AW), whereas the presence of the Levantine Intermediate Water (LIW) was observed south of Crete. The vertical distribution of both DOC and humic-like FDOM was strongly affected by the water masses circulation and water column stratification. In the upper 200 m, DOC markedly increased from 50 to 80 &amp;#956;M moving eastward, likewise the protein-like component dominates the upper layer and increased moving from Gibraltar to Crete. In contrast, the humic-like components showed a minimum in the surface layer, and a decreasing moving eastward, probably due to photobleaching. The PAH-like component showed its maximum in correspondence with the areas characterized by intensive naval traffic. The accumulation of DOC, observed in the EMED, could be explained by a change in DOM quality, supported by the differences in FDOM.&lt;/p&gt;&lt;p&gt;In 2 selected stations, the fluorescence of humic-like and protein-like compounds was also measured along the water column by using the new fluorescence sensor and compared with PARAFAC results, in order to evaluate its performance for open sea waters.&lt;/p&gt;

scholarly journals Isotope fractionation between dissolved and suspended particulate Fe in the oxic and anoxic water column of the Baltic Sea

2013 ◽  
Vol 10 (1) ◽  
pp. 233-245 ◽  
Author(s):  
M. Staubwasser ◽  
R. Schoenberg ◽  
F. von Blanckenburg ◽  
S. Krüger ◽  
C. Pohl
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Isotope Composition ◽  
Open Water ◽  
Deep Basin ◽  
Strong Concentration ◽  
Suspended Particulate ◽  
Oxidative Precipitation ◽  
The Difference ◽  
The Baltic

Abstract. Fe isotope ratios and concentrations of dissolved Fe (Fedis, < 0.45 μm) and of suspended particulate Fe (FeSPM) were analyzed from a depth profile through the anoxic Eastern Gotland Basin water column, Baltic Sea. Results show a sharp gradient in δ56Fedis across the ferruginous layer with δ56Fedis = −0.4‰ in the euxinic deep basin and δ56Fedis = &amp;plus;0.3‰ in the oxic upper water column. The isotopic gradient overlaps with a strong concentration gradient of Fedis, a concentration maximum in FeSPM and lower δ56FeSPM values than δ56Fedis. These features indicate preferential loss of light Fe isotopes from solution to suspended iron-oxyhydroxides (FeIOH) during typical oxidative precipitation across the redox interface. The sign of the overall fractionation, Δ56FeIOH-Fe(II)(aq) < 0‰, is in contrast to similar, mostly non-marine redox environments, where Δ56FeIOH-Fe(II)(aq) > 0‰. The difference appears to be the result of isotope exchange dominated by reaction kinetics in the marine water column, rather than equilibrium fractionation generally inferred for oxidative Fe precipitation elsewhere. High residual δ56Fedis immediately above the oxic–ferruginous interface and throughout the oxic water column suggests that any potential dissolved Fe export from marine reducing waters into the oxic open water column is enriched in the heavy isotopes. In the deep, mildly euxinic water column above the level of Fe sulfide saturation, a decreasing δ56FeSPM trend with depth and a generally low δ56Fedis are comparable to trends generally observed in marine anoxic sediment profiles where microbial reductive Fe dissolution occurs. The isotope composition of the redox-cycled Fe inventory in anoxic marine basins mainly reflects the balance between external fluxes, driving the composition towards crustal δ56Fe values, and intensity of internal recycling, driving δ56Fe towards negative values.

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