Tank Experiments Research Articles

Simplified estimation of wave attenuation in marginal ice zone using homogenized scattering model

A theoretical model to explain the scattering process of wave attenuation in a marginal ice zone is proposed. Although many numerical methods have been developed to accurately estimate wave attenuation, it is not easy to incorporate this knowledge and results into practical use. Therefore, a simplified estimation method is developed here to explicitly and simply describe its fundamental mechanisms. We consider a periodic array of ice floes, where the floe is modeled by a vertical rigid cylinder. Using a homogenization technique, a homogenized free surface equivalent to the array is obtained. Then, we show that a dispersion relation of the homogenized free surface waves makes all wave numbers complex. As a result, the exponential energy decay in the scattering process is demonstrated. Under the deep water assumption, the wave attenuation coefficient is proportional to the open water’s wave number, ice concentration ratio, and imaginary part of the floe’s heave motion. To validate the proposed theory, a tank experiment was also conducted using cylindrical synthetic ice plates. Although our model is obtained under many simplifications, the theoretical results show the same tendency and order as the experimental results.

The retrofitting of ships by applying retractable bow hydrofoils: a case study

Increasing environmental requirements and a relatively long ship life of 30 years mean more attention is needed to retrofit existing ships. One possibility is using hydrofoils to reduce the ship’s resistance and improve comfort and safety in rough sea conditions. This study investigates the influence of retractable bow hydrofoils on the seakeeping performance and operational conditions of a selected case study vessel (V-shaped bulbous bow). The methods used were full-scale computational fluid dynamics (CFD) simulations and towing tank experiments for validation. The analysis was conducted for bow waves of different lengths and a ship’s operating speed. The most beneficial effect of hydrofoils was observed for wavelengths from λ/LWL = 1.0 to λ/LWL = 1.2. For the wavelength λ/LWL = 1.2, the reduction of heave motion was equal to 33%, pitch motion was equivalent to 28%, and the reduction of wave-added resistance was equal to 25%. The analysis also showed unfavourable conditions for which hydrofoil folding is needed to avoid causing an excessive increase in resistance. A generalized procedure has been developed to assess the potential for resistance and motion reduction by retrofitting existing ships using hydrofoils.

Plastic pollution in riverbeds fundamentally affects natural sand transport processes

Over the past 50 years, rivers have become increasingly important vectors for plastic pollution. Lowland riverbeds exhibit coherent morphological features including ripple and dune bedforms, which transport sediment downstream via well-understood processes, yet the impact of plastic on sediment transport mechanics is largely unknown. Here we use flume tank experiments to show that when plastic particles are introduced to sandy riverbeds, even at relatively low concentrations, novel bedform morphologies and altered processes emerge, including irregular bedform stoss erosion and dune “washout”, causing topographic bedform amplitudes to decline. We detail (i) new mechanisms of plastic incorporation and transport in riverbed dunes, and (ii) how sedimentary processes are fundamentally influenced. Our laboratory flume tank experiments suggest that plastic is not a passive component of river systems but directly affects bed topography and locally increases the proportion of sand suspended in the water column, which at larger scales, has the potential to impact river ecosystems and wider landscapes. The resulting plastic distribution in the sediment is heterogeneous, highlighting the challenge of representatively sampling plastic concentrations in river sediments. Our insights are part of an ongoing suite of efforts contributing to the establishment of a new branch of process sedimentology: plastic – riverbed sand interactions.

Indigenous food sources as vectors of Escherichia coli and antibiotic resistance

The contamination of surface waters by fecal bacteria, measured by the number of Escherichia coli, is a significant public health issue. When these bacteria are also resistant to antimicrobials, infections are more complicated to treat. While water is regularly tested at recreational sites, wild-harvested foods, known as mahinga kai by the indigenous Māori people of Aotearoa New Zealand, are commonly overlooked as a source of exposure to potential pathogens and antimicrobial resistance (AMR). We investigate two likely sources of risk from harvesting aquatic wild foods. The first is water contact, and the second is contact with/ingestion of the harvest. We used E. coli as a proxy for microbial water quality at harvesting sites. Two popular mahinga kai species were also harvested and assessed. We found antibiotic-resistant bacteria on watercress (Nasturtium officinale) and cockles (Austrovenus stutchburyi). One-third of E. coli isolates were conjugative donors of at least one resistance phenotype. Tank experiments were used to track the internalization of E. coli by Greenshell/lip mussels (Perna canaliculus). Greenshell mussels kept at environmentally relevant concentrations of E. coli were colonized to levels considered unsafe for human consumption in 24 h. Finally, we measured horizontal gene transfer between bacteria within the shellfish, what we termed ‘intra-shellular’ conjugation. The transmission frequency of plasmid RP4 was significantly higher in mussels than in water alone. Our results indicate that shellfish could promote the dissemination of antibiotic resistance. They highlight the need to limit or reduce human pathogenic bacteria where food is gathered.

Hydrodynamics Analysis of an Underwater Foldable Arm

Improved designs for underwater manipulators are becoming increasingly important due to their utility in academic and industrial applications. In this work, an experiment was conducted in conjunction with a numerical simulation to investigate the hydrodynamic performance and structural reliability of the proposed foldable arm during the unfolding process at various movement velocities. A large-scale geometric model of the foldable arm with a single degree of freedom (DOF) was constructed. The distribution of the flow field, the movement stability and the equivalent stress of the foldable arm were quantitatively analyzed with a designed tank experiment and the Computational Fluid Dynamics (CFD) simulation. Simulation results show that the maximum deviation of the resistance and torque is 8.04% and 5.73%, respectively, compared with the experimental results of static postures. Comparison results prove the reliability of the numerical model. The results of transient simulation demonstrate that the optimal speed of the foldable arm is 3 Kn and the pressure distribution on the surface of foldable arm is relatively regular. Furthermore, a fluid–structure interaction (FSI) validation study of the foldable arm was presented. For the coupling between the fluid and structural mechanics domains, a nonmatching discretization approach was adopted. The results show that the directional deformation (Z axis) of the foldable arm is less than 0.50 mm. The proposed foldable arm has a large angle of rotation and high stability compared to the existing manipulators.

Phase-resolved real-time forecasting of three-dimensional ocean waves via machine learning and wave tank experiments

Accurate prediction of ocean waves plays an essential role in many ocean engineering applications, such as the control of wave energy converters and floating wind turbines. However, existing studies on phase-resolved wave prediction using machine learning mainly focus on two-dimensional wave data, while ocean waves are usually three-dimensional. In this work, we investigate, for the first time, the phase-resolved real-time prediction of three-dimensional waves using machine learning methods. Specifically, the wave prediction is modeled as a supervised learning task aiming at learning mapping relationships between the input historical wave data and the output future wave elevations. Four frequently-used machine learning methods are employed to tackle this task and a novel Dual-Branch Network (DBNet) is proposed for performance improvement. A group of wave basin experiments with nine directional wave spectra under three sea states are first conducted to collect the data of 3D waves. Then the wave data are used for verifying the effectiveness of the machine learning methods. The results demonstrate that the upstream wave data measured by the gauge array can be used for control-oriented wave forecasting with a forecasting horizon of more than 20 s, where the directional information provided by the upstream gauge array is vital for accurately predicting the downstream wave elevations. In addition, further investigations show that by using only local wave data (which can be easily obtained), the very short-term phase-resolved prediction (less than 5 s) can be achieved.

On the role of organic matter composition in fresh-water kaolinite flocculation

Organic matter has long been understood to affect fine sediment flocculation, yet the specific effects of different types of organic matter remain only partially understood. To address this knowledge gap, laboratory tank experiments were conducted in fresh water to investigate the sensitivity of kaolinite flocculation to varying organic matter species and contents. Three species of organic matter (xanthan gum, guar gum and humic acid) were investigated at varying concentrations. Results revealed a significant enhancement in kaolinite flocculation when organic polymers (xanthan gum and guar gum) were introduced. In contrast, the addition of humic acid had minimal influence on aggregation and floc structure. Notably, the nonionic polymer guar gum demonstrated greater efficacy in promoting the development of floc size compared to the anionic polymer, xanthan gum. We observed non-linear trends in the evolution of mean floc size (Dm) and boundary fractal dimension (Np) with increasing ratios of organic polymer concentration to kaolinite concentration. Initially, increasing polymer content facilitated the formation of larger and more fractal flocs. However, beyond a certain threshold, further increases in polymer content hindered flocculation and even led to the break-up of macro-flocs, resulting in the formation of more spherical and compact flocs. We further quantified the co-relationships between floc Np and Dm and found that larger Np values corresponded to larger Dm. These findings highlight the significant impact of organic matter species and concentrations on floc size, shape and structure, and shed light on the complex dynamics of fine sediment and associated nutrients and contaminants in fluvial systems.

Snow crab (Chionoecetes opilio) hemocytes and hepatopancreas transcriptomes: identification, validation, and application of immune-relevant biomarkers of exposure to noise

The snow crab (Chionoecetes opilio) fishery off the east coast of Newfoundland and Labrador, Canada, has been impacted by annual seismic oil and gas surveying in recent decades, and commercial crab harvesters are concerned that it could potentially affect this resource. A laboratory study was performed to investigate the effects of chronic noise exposure on the transcriptomes of snow crab hemocytes and hepatopancreas, which are important in immunity, metabolism and response to environmental stress. Snow crab were held in replicate control or experimental tanks; on alternating days, the experimental tanks were exposed to noise from an underwater speaker which played a recording of a seismic airgun firing every 10 sec in a continuous loop for ~ 22 weeks (chronic noise). RNA sequencing was used to identify candidate noise-responsive molecular biomarkers in both hemocytes and hepatopancreas. The quantified transcripts of individuals (i.e. n=10 from each of the four groups) were compared using DESeq2, identifying over 300 noise-responsive transcripts in each cell/tissue type. Real-time quantitative polymerase chain reaction (qPCR) assays were designed and run for 61 of these transcripts with significant BLASTx hits. One transcript (rgs2) was significantly (p < 0.05) higher expressed in both hemocytes and hepatopancreas in response to noise; five and seven other transcripts were either significant or showed a non-significant trend of differential expression (0.05 < p ≤ 0.1) in hemocytes (e.g. cfb upregulated, sacs and myof downregulated) and hepatopancreas (e.g. gpx3 and atf3 upregulated, sult1c4 downregulated), respectively. To further investigate the performance and utility of these candidate biomarkers in the field, expression levels of 25 selected transcripts were then examined in the hepatopancreas of snow crab that had been subjected to 2D and 3D seismic surveying using both qPCR and multivariate statistical analyses. Overall, few of these biomarkers showed consistent results in field-collected snow crab, highlighting the need to combine lab and field-based studies to fully evaluate the utility of biomarkers. Nonetheless, our study still identified noise-responsive biomarkers in both settings (including stress and immune relevant genes), providing valuable information for understanding the impact of ocean noise on snow crab physiology and health.

A universal wireless charging platform with novel bulged‐structure transmitter design for multiple heterogeneous autonomous underwater vehicles (AUVs)

AbstractAutonomous underwater vehicles (AUVs) are important mobile equipment for ocean observation. Subsea docking stations are used to charge AUV batteries to increase their cruise duration. Here, a universal wireless charging platform with a novel transmitter is developed to address the issues of poor compatibility existing in conventional docking stations. In order to guarantee a sufficient charging area and reduce copper losses, the proposed transmitter is designed to have a bulged‐structure surrounding coil and a centre coil in coaxial. Moreover, the parameters of the transmitter that impact the magnetic flux density are analysed and optimized by non‐linear programming by Quadratic Lagrangian (NLPQL) algorithm to achieve a field with desirable intensity and uniformity. The characteristics of the circuits under single‐load and double‐load conditions have been tested in air and tank experiments. The results verify that the proposed platform achieves both the universality and misalignment tolerance requirements.

Time-domain Kirchhoff approximation extensions modeling of acoustic camera imagery with multiple scattering

High-frequency acoustic cameras have provided high-resolution sonar images to enable the development of signal processing algorithms, such as 3-D reconstruction, target recognition, and precision navigation. However, the lack of large datasets has hampered the development of such algorithms. In this context, this paper proposes a time-domain Kirchhoff approximation extensions (TDKAX)-based model to generate realistic acoustic camera images, capable of accounting for multiple scattering from arbitrary-shapetargets. The images are formed by a coherent summation of different orders of transient echoes, along with a pipeline of the range conversion, time-varying gain compensation, noise addition, and image rendering. Validating the proposed model using tank experiments of isolated cylindrical concave reflectors, we then present the ray paths based on the coordinates of intersection points. They can help interpret the mechanism of image features in the absence of amplitude information. Results demonstrate that, with the temporal and spatial coherence of different orders of scattering, the proposed model successfully reproduces forward-looking sonar (FLS) images with multiple scattering arcs and coherent speckles.

Sub-lethal toxicity of indigo dye (Indigofera tinctoria) on Oreochromis niloticus juveniles

BackgroundTextile dyes which are eliminated as unfixed dyes through the effluent from textile industry cause deleterious effect on the fresh water fish. Thus, toxicity tests were conducted using indigo dye on Oreochromis niloticus juveniles (mean weight 30.00 ± 0.73 g) as a test fish under bioassay system. Varying concentration of 0.00 (control), 0.5, 1.0, 1.5, 2.0, and 2.5 mg/l containing graded levels of Indigofera were applied in experimental tanks to determine the lethal concentration. The LC50 of dye at 96 h was 1.3 mg/l of water. The histopathology (heart, gills, kidney and spleen) and water quality parameters (Dissolved oxygen, pH and temperature) were determined using standard methods and behavioural responses were observed.ResultsHistopathology of heart, gills, kidney and spleen revealed degeneration of cells, space formation, slight cellular changes and vacuolation among the treatments especially in the higher concentration of 1.5 mg/l, 2.0 mg/l, and 2.5 mg/l of the dye solution used except in the control. The pH and DO of control were significantly different from the experimental units while there was no significant variation in the temperature of the control and all the experimental units. Effects of indigo dye on water parameters were significant (P < 0.05) throughout the experiment. Behavioural responses exhibited by the experimental fish include irregular swimming, hyperventilation, rapid opercula movement, and restlessness. The dye concentration and exposure period both boosted these behaviours.ConclusionsThe findings of this study indicated that indigo dye solution is toxic to fish, and that fish opercula movement and mortality were influenced by the dosage of each concentration and the duration of exposure.

Effect of C/N Ratio Levels and Stocking Density of Catla Spawn (Gibelion catla) on Water Quality, Growth Performance, and Biofloc Nutritional Composition in an Indoor Biofloc System

A 20-day 3 ∗ 3 factorial experiment was conducted in 100 L HDPE experimental tanks to investigate the effect of the C/N ratio (10, 15, and 20) and stocking density (3, 4, and 5 spawn L−1) on Gibelion catla spawn nursery rearing in the indoor biofloc system. Rice bran was used as the carbon source for manipulating C/N ratios. Each treatment was stocked with catla spawn of average length (6.7 ± 0.4 mm) and average weight (1.6 ± 0.2 mg). Water parameters showed that increasing the C/N ratio from 10 to 20 significantly ( p &lt; 0.05 ) reduced total ammonia nitrogen (TAN) and nitrite nitrogen (NO2-N) and increased nitrate nitrogen (NO3-N) in the water. The insignificant difference ( p &gt; 0.05 ) and lowest final average length, average length gain, average weight gain, and specific growth rate (SGR) were recorded in C/N ratios of 10 and 15 compared to a C/N ratio of 20. A significant difference ( p &lt; 0.05 ) in survival was observed with the increasing C/N ratio. Increasing the fish stocking density resulted in higher mortality. However, a higher amount of fry produced was observed in the treatments with 3 and 4 spawn L−1. Crude protein content increased significantly ( p &lt; 0.05 ) with the increasing C/N ratio with higher content in C/N 20. No significant difference ( p &gt; 0.05 ) in proximate composition of biofloc was observed in different stocking density groups. In conclusion, the application of the biofloc technology with a C/N ratio of 20 at a stocking density of 4 spawn L−1 could be recommended to increase the production of catla fry in the indoor biofloc system.

Assessing chamomile and marjoram meals as feed additives on growth indices and haematological parameters of Nile tilapia (Oreochromis niloticus) reared under biofloc system

First report on using chamomile (Matricaria chamomilla) flower meal [CFM] and marjoram (Origanum majorana) leaves meal [MLM] as dietary supplements in low-protein fish diets on Nile tilapia (Oreochromis niloticus) reared in a bio-floc system. The experiment consisted of 6 groups in triplicates, where the first (T1) and second (T2) groups were fed diets containing 25 and 20% protein, respectively, without any additives. In contrast, the rest of the groups were fed a 20% protein diet, adding CFM at rates of 1% (T3) and 2% (T4) or MLM at rates of 1% (T5) and 2% (T6). The fish were initially weighed 18.44 g ± 0.38 (S.E.) and randomly stocked in 18 experimental tanks at six fingerlings in a water volume of 40 litres (150 fish/m3). Molasses was used as a carbon source with a carbon-to-nitrogen ratio of 16:1 in the treatments fed 20% protein; 12:1 in the treatments provided 25% protein. Feeding was done twice daily, six days a week, at a rate of 3% of body weight for 42 days. Water quality was within the desirable tilapia growth and health limit regarding temperature (23.20 - 24.70 °C), pH (8.43 - 8.65), dissolved oxygen (5.5 - 6.1 mg/L), and NH3 (0.03–0.051 mg/L). Fish fed on a 20% CP diet containing 1% CFM had the highest values in all growth indicators, followed by 2% CFM and 1% MLM then T1 and T2 groups. Blood analysis showed variation (P ≤ 0.05) among groups, and T3 had the highest levels of hemoglobin (Hb), hematocrit (Hct), and red blood cells (RBCs) followed by T5 then T4, T2, while T6 and T1 were the least. In conclusion, using chamomile or marjoram as a feed supplement maximizes the benefits of using the bio-floc system, especially in a lack of water resources and poor protein feeds. Nile tilapia growth and hematological parameters were the best with a 1% chamomile (M. chamomilla) supplement under a biofloc system.

An improved method for estimating the dissipation rate of turbulent kinetic energy using structure functions evaluated from the motion of finite-sized neutrally buoyant particles

Statistical relations used for estimating the dissipation rate of turbulent kinetic energy (TKE) in isotropic turbulence from the inertial subrange of Lagrangian temporal and spatial structure functions are extended here to the case of more realistic turbulence spectra that include low-frequency and low-wavenumber ranges. It is shown that using the traditional relations based only on the inertial subrange substantially underestimates the dissipation. The improved relations are better constrained by experimental data from which the dissipation is evaluated, enabling more accurate dissipation estimates. The concept is illustrated using laboratory data from water tank experiments of turbulence generated by an oscillating cylinder, where the dissipation is evaluated in three independent ways: from Lagrangian spectra and from Lagrangian temporal and spatial structure functions calculated from the motion of neutrally buoyant finite-sized particles. An additional correction to the relations for estimating the dissipation from the spatial structure functions is applied to take into account the filtering effect of the particles due to their finite size. It is found that, for these particular experiments, the TKE dissipation rate scales well with dimensionally consistent quantities built using the amplitude of the oscillation of the cylinder and the period of its motion, and the constant of proportionality in this scaling relation is determined using the method proposed here. Although the turbulence under consideration is quite anisotropic, the adopted theoretical framework, which assumes isotropic turbulence, seems to be applicable to the experimental data as long as the turbulence statistics are averaged over the three main flow directions.

A comparison of regression models for the ice loads measured during the ice tank test

To evaluate the time-domain positioning performance of arctic marine structures, it is necessary to generate an ice load appropriate for the current position and heading of the structure. The position and orientation angle of a floating body continuously change with time. Therefore, an ice load is required for any attitude in the time-domain simulation. In this study, we present a fundamental technique for analyzing ice loads in the frequency domain based on data measured at various angles in the ice-water tank experiment. We perform spectral analysis instead of general FFT to analyze the ice load, which has the characteristics of a random signal. To generate the necessary ice load in the time domain, we must first interpolate the measured data in the frequency domain. Using the Blackman-Tukey method, we estimate the spectrum for the measured data, then process the data to generate the training set required for machine learning. Based on the results, we perform regression analysis by applying four representative techniques, including linear regression, random forest, or neural network, and compare the results with MSE. The deep neural network method performed best, but we provide further discussion for each model.

Investigation of the optimum longitudinal single transverse step location for a high-speed craft

One of the crucial aspects of the conceptual design of a stepped planing hull is the prediction of its performance. To improve performance, the prediction of total resistance must become more accurate. In the field of research, both towing tank experiments and numerical analysis may be used to achieve this goal. In this study, experiments were conducted initially to investigate total resistance of a relatively high-speed craft without a transverse step. Later, numerical computations were carried out to validate the experimental results. After it was determined that the test results and CFD methods were in good agreement, the experimental method continued to investigate the resistance properties of the hull with four different configurations to evaluate the optimal longitudinal position of a single transverse step. The ideal longitudinal position of the single transverse step was evaluated based on a similar relatively high-speed hull with a velocity of up to beam Froude number (FrB) 2.56 in this study, focusing on the FrB range between 2.30 and 2.45.

Seawater alkalinity enhancement with magnesium hydroxide and its implication for carbon dioxide removal

For the first time we used lab and wind-wave tank experiments to prove the concept of using Mg(OH)2 for the ocean alkalinity enhancement and carbon dioxide removal approach (OAE-CDR). Experiment results showed up to 370 μmol kg−1 seawater total alkalinity (TA) increase without precipitation, stable enhanced TA, and OAE-CDR efficiency (ΔDIC/ΔTA) consistent with theoretical calculation. Based on the experimental results, we calculated the global Mg(OH)2 OAE-CDR efficiency and CO2 sink from this approach. The efficiency is in favor of lower initial DIC to TA ratio, lower temperature, and higher atmospheric CO2, and therefore is the lowest at the equator (0.7–0.8) and increases with latitude (1.0–1.2 above 70 N/S). However, factoring in the ocean's surface area, low latitude regions can absorb more atmospheric CO2. We conservatively estimate that 44. 4 × 109 ton of CO2 (∼ 3.3 times of current annual CO2 sink in the ocean) could be removed from the atmosphere with 175 μmol kg−1 Mg(OH)2 (equivalent to 350 μmol kg−1 of TA) added to the top 10 m of the ocean.

Laboratory experiments on coastal current separation and vortex formation in front of Cabo Corrientes and Bahía de Banderas, México

A series of rotating tank experiments are carried out to study the behaviour of a coastal current when encountering a cape and an adjacent bay. The experiments are designed to represent some essential dynamics of the interaction of the Mexican Coastal Current with Cabo Corrientes and Bahía de Banderas on the western coast of Mexico. The experiments show that the current surrounds the cape and accumulates negative relative vorticity in front of the downstream bay. For sufficiently strong currents, the flow separates from the coast and the accumulated vorticity develops an anticyclonic eddy that drifts away from the generation region. Afterwards, the current is re-established and the process is repeated. The periodicity is about 16 periods of the rotating system. The current separation and vortex formation depend on the ratio between the inertial length of the current (defined as the characteristic speed over the Coriolis parameter) and the coastal radius of curvature associated with the cape. Another mechanism for vortex formation is verified when the coastal current is switched off. The current separation and eventual vortex shedding are further studied in additional experiments without the cape or the bay, thus increasing the effective coastal radius of curvature. It is verified that the absence of any of these two features inhibits the current separation. The results illustrate the dynamical conditions that may help to explain the emergence of mesoscale oceanic eddies observed on the lee side of Cabo Corrientes, especially during the summer. This assertion is explored by examining historical data from the GLORYS12V1 reanalysis, in which current separation and eddy-shedding events are found and compared with the experimental observations.

Characteristics of persulfate gel materials in groundwater remediation: Column and tank experiments investigations

Using persulfate and environment–friendly gel solution as raw materials, persulfate gel sustained–release material (PGSR) and persulfate gelatin gel sustained–release material (G–PGSR) were developed. The main purpose of this study was to evaluate the potential of PGSR and G–PGSR in sustained release, migration and removal performance through column and tank experimental investigations. Results showed that the maximum release rates of PGSR and G–PGSR in water columns were 1.34 and 0.58 mg min−1 and the cumulative release amounts achieved 2950 and 2818 mg within 75 h, representing release efficiencies of 98.3 % and 93.9 %, respectively. In three sand columns, the maximum release rate was 0.32, 0.21, and 0.16 mg min−1 and the cumulative release achieved 473, 426, and 359 mg within 90 h with release efficiencies of 94.7 %, 85.3 %, and 71.7 %, respectively. Release time and rate of PGSR and G–PGSR are constrained by the permeability of porous media. G–PGSR in the sand tank exhibited migration and release characteristic with the slow–release diffusion effect. Lateral diffusion produced higher S2O82− concentration far beyond what was allowed in the tank. The saturated hydraulic conductivity decreased from 4.9 × 10−3, 1.1 × 10−3, and 4.9 × 10−4 cm s−1 to 2.4 × 10−3, 7.4 × 10−4, and 2.1 × 10−4 cm s−1 in columns filled with medium, fine, and silt, respectively. G–PGSR injection did not significantly change the order of magnitude of hydraulic conductivity. 2,4–dinitrotoluene removal performance was affected with the inlet flow rates, which decreased from 92 %, 82 %, and 78 % to 42 %, 28 %, and 8 % during 24 PV at the flow rate of 0.5, 1.5, and 4.5 mL min−1, respectively. Moreover, the removal efficiency was enhanced by G–PGSR with activated carbon as an activator. This study expands our understanding and ability of persulfate gel materials for groundwater remediation and provides a certain research basis for practical applications.

The Antarctic Scallop Adamussium colbecki Is Unable to Transcriptomically Respond to Captivity and Moderate Thermal Stress

Adamussium colbecki is a scallop endemic of the Antarctic Ocean, the only modern survivor of the Adamussiini tribe and one of the few bivalves living in polar environments. Compared with other Antarctic animals, very little is known concerning the evolutionary adaptations which allow this species to thrive at sub-zero temperatures. Due to its local abundance and sensitivity to environmental changes, A. colbecki is an interesting model for studying the effects of pollution and climate change in the Antarctic Ocean. Here, we report, for the first time, the application of transcriptomic tools to the study of the effects of a short-to-medium term exposure to a +1.5 °C water temperature increase on three tissues. Although this approach did not highlight any significant change in response to thermal stress, we observed slight alterations in energetic metabolism and nutrient adsorption in the digestive gland, most likely linked with stabling in experimental tanks. The results of our study suggest that A. colbecki may be particularly vulnerable to the effects of climate change due to its complete inability to adapt to temperature increase at the transcriptomic level.