Tracking Fluorescent Dye Dispersion from an Unmanned Aerial Vehicle

Commercial unmanned aerial vehicles continue to gain popularity and their use for collecting image data and recording new phenomena is becoming more frequent. This study presents an effective method for measuring the concentration of fluorescent dyes (fluorescein and Rhodamine WT) for the purpose of providing a mathematical dispersion model. Image data obtained using a typical visible-light camera was used to measure the concentration of the dye floating on water. The reference measurement was taken using a laboratory fluorometer. The article presents the details of three extensive measurement sessions and presents elements of a newly developed method for measuring fluorescent tracer concentrations. The said method provides tracer concentration maps presented on the example of an orthophoto within a 2 × 2 m discrete grid.

Verifying the extent of plumes from produced formation water: a Wheatstone case study

Chevron Australia Pty Ltd operates the Wheatstone liquefied natural gas facility in Western Australia under a Joint Operating agreement. Hydrocarbons from Wheatstone, Iago and Julimar-Brunello fields are sent to the Wheatstone Platform (the Platform), located ~50 km north of the Montebello Islands, for dewatering and dehydration before being transported onshore for final processing. Produced formation water (PW) is processed (treated) and, once criteria are met, discharged overboard. PW at Wheatstone is predicted to rapidly dilute in the receiving ocean to concentrations below water quality criteria (Australian and New Zealand Environment Conservation Council guidelines and ecotoxicology), though empirical evidence is needed to verify the actual discharge risk. Seawater (i.e. cooling water, CW) is also abstracted for cooling duty on the Platform, chlorinated and discharged. This paper describes a field verification campaign aimed at understanding PW and CW behaviour in the water column post-discharge, dilution with distance and whether numerical modelling of dilutions is accurate. The campaign was designed to evaluate plume characteristics by monitoring both entrained PW constituents (i.e. hydrocarbons and metals) and using a Rhodamine WT tracer dye. Monitoring of these constituents was done using an array of sampling techniques, including fluorometry, remotely operated vehicles and discrete water samplers. Results indicate rapid dilutions post PW and CW discharge, with dye fluorometry proving a valuable tool for understanding plume characteristics. Water sampling data interpretation indicated dilutions were likely orders of magnitude greater than anticipated, likely due to variable flow effects and turbulence induced by the Platform structure for PW, and the influence of entrained air within the plume for CW.

Reducing the Pore Size of Covalent Organic Frameworks in Thin-Film Composite Membranes Enhances Solute Rejection

Three imine-linked covalent organic framework (COF) films are incorporated as active layers into separate thin-film composite (TFC) membranes and tested for their ability to reject an organic pollutant surrogate and salt from water. The synthesized membranes consist of a polyacrylonitrile (PAN) membrane supporting a <b>TAPB-PDA-H</b>, <b>TAPB-PDA-Me</b>, or <b>TAPB-PDA-Et</b> COF thin film. The latter two COFs direct six methyl and ethyl substituents per tiled hexagon into the pores, respectively, while maintaining the same topology across the series. These substituents decrease the effective pore size of the COF compared to the parent <b>TAPB-PDA-H</b> COF. The <b>TAPB-PDA-Me</b> membrane rejects Rhodamine-WT (R-WT) dye and NaCl better than the <b>TAPB-PDA-H</b> membrane, and the <b>TAPB-PDA-Et</b> membrane exhibits the best rejection overall. The solution-diffusion model used to analyze this permeation behavior indicates that there is a systematic difference in rejection as subsequent pendant groups are added to the interior of the COF pore. These findings demonstrate the concept of tuning the selectivity of COF membranes by systematically reducing the effective pore size within a given topology.<br>

Reducing the Pore Size of Covalent Organic Frameworks in Thin-Film Composite Membranes Enhances Solute Rejection

Three imine-linked covalent organic framework (COF) films are incorporated as active layers into separate thin-film composite (TFC) membranes and tested for their ability to reject an organic pollutant surrogate and salt from water. The synthesized membranes consist of a polyacrylonitrile (PAN) membrane supporting a <b>TAPB-PDA-H</b>, <b>TAPB-PDA-Me</b>, or <b>TAPB-PDA-Et</b> COF thin film. The latter two COFs direct six methyl and ethyl substituents per tiled hexagon into the pores, respectively, while maintaining the same topology across the series. These substituents decrease the effective pore size of the COF compared to the parent <b>TAPB-PDA-H</b> COF. The <b>TAPB-PDA-Me</b> membrane rejects Rhodamine-WT (R-WT) dye and NaCl better than the <b>TAPB-PDA-H</b> membrane, and the <b>TAPB-PDA-Et</b> membrane exhibits the best rejection overall. The solution-diffusion model used to analyze this permeation behavior indicates that there is a systematic difference in rejection as subsequent pendant groups are added to the interior of the COF pore. These findings demonstrate the concept of tuning the selectivity of COF membranes by systematically reducing the effective pore size within a given topology.<br>

New methods for predicting and measuring dispersion in rivers

To develop a better predictive tool for dispersion in rivers over a range of temporal and spatial scales, our group has developed a simple Lagrangian model that is applicable for a wide range of coordinate systems and flow modeling methodologies. The approach allows dispersion computations for a large suite of discretizations, model dimensions (1-, 2-, or 3-dimensional), spatial and temporal discretization, and turbulence closures. As the model is based on a discrete non-interacting particle approach, parallelization is straightforward, such that simulations with large numbers of particles are tractable. Results from the approach are compared to dispersion measurements made with conventional Rhodamine WT dye experiment in which typical at-a-point sensors are employed to determine concentration. The model performs well, but spatial resolution for experiments over large and or complex river flows was inadequate for model testing. To address this issue, we explored the idea of measuring spatial concentrations in river flows using hyperspectral remote sensing. Experiments both for idealized channels and real rivers show that this technique is viable and can provide high levels of spatial detail in concentration measurements with quantitatively accurate concentrations.

Investigations On Water Circulation in Animal Sea-Water Basins – On the Example of Seals′ Breeding Pools

This paper presents general comments concerning investigations on water circulation in animal breeding pools containing sea water. As an example are given results of computer simulation of water circulation in seals′ breeding pools situated in Marine Station at Hel, belonging to Oceanographic Institute , Gdansk University. A mathematical model of three main pools was prepared with taking into account their inflow and outflow water supply points. Next, the object indication ( tracer) tests were done with the use of mathematical modelling as well as in-situ measurements. For description of flow field in steady conditions a simplified model of 2D flow in the form of Helmholtz biharmonic equation of stream function , recalculated then into velocity vector components, was used. The equation , supplemented with appropriate boundary conditions , was solved numerically by using the finite differences method. The spreading of a substance dissolved in water (tracer) was analyzed by solving 2D equation of transient advecting - dispersing transport. To solve it the finite volumes method was applied. The applied model was verified by conducting the indication tests with the use of the rhodamine WT as a tracer. The obtained results made it possible to reconstruct water circulation within the seals′ pools and identify stagnation zones in which water circulation may be made difficult.

Application of Heterogeneous Robotic System for Underwater Oil Spill Scenario

The tragic Deepwater Horizon accident in the Gulf of Mexico in 2010 as well as the increase in deepwater offshore activity have increased public interest in counter-measures available for subsurface releases of hydrocarbons. To arrive at proper contingency planning, response managers urge for a system for instant detection and characterization of accidental releases. Along these lines, this paper describes the application of a heterogeneous robotic system of unmanned vehicles: autonomous underwater vehicle (AUV), unmanned surface vehicle (USV) and unmanned aerial vehicle (UAV) extended with the oil spill numerical modeling, visualisation and decision support capabilities. A first set of field experiments simulating oil spill scenarios with Rhodamine WT was held in Croatia during the early autumn 2014. and the second set of experiments were held in Spain during the summer 2015. The objectives of this experiment were to test: effectiveness of the system for underwater detection of hydrocarbons, heterogeneous multi-vehicle collaborative navigation and communication as well as decision support system, visualisation of the system components and detected spill.