Impact of atmospheric deposition on the dynamics of ultraphytoplanktonic populations in the Gulf of Gabès during an intense dust event (MERITE-HIPPOCAMPE campaign).

The ultraphytoplankton composition and dynamics were assessed during a Saharan dust event occurring off the southern Tunisian coasts during the MERITE-HIPPOCAMPE Trans-Mediterranean oceanographic cruise. The composition of atmospheric dust was characterized in terms of nutriments and trace metals. Data-assimilative hydrodynamic model revealed no differences in the hydrological features along the sampling track and almost no water transport occurred during the period of atmospheric deposition. Dust deposition increased the growth rates and the productivity of the major phytoplanktonic cytometric groups, resulting in the highest surface biomass along the Mediterranean transect. One group, distinguished by low fluorescence and nanoplanktonic size, reacted to dust deposition within hours, exhibiting the highest growth rate and net productivity. The dust composition showed a substantial enrichment with organic phosphorous representing (56 % of Total phosphorus) and trace metals mainly Fe, Mn and V.

Relative sensitivity of hydrodynamic, thermodynamic, and chemical processes for simulating the buoyant multiphase plume and surfacing flows of an oil and gas blowout.

Deepwater hydrocarbon releases experience complex chemical and physical processes. To assess simplifications of these processes on model predictions, we present a sensitivity analysis using simulations for the Deepwater Horizon oil spill. We compare the buoyant multiphase plume metrics (trap height, rise time etc), the hydrocarbon mass flowrates at the near-field plume termination and their mass fractions dissolved in the water column and reaching the water surface. The baseline simulation utilizes a 19-component hydrocarbon model, live-fluid state equations, hydrate dynamics, and heat and mass transfer. Other simulations turn-off each of these processes, with the simplest one using inert oil and methane gas. Plume metrics are the least sensitive to the modeled processes and can be matched by adjusting the release buoyancy flux. The mass flowrate metrics are more sensitive. Both liquid- and gas-phase mass transfer should be modeled for accurate tracking of soluble components (e.g. C1 - C7 hydrocarbons) in the environment.

Downstream Transport of Geosmin Based on Harmful Cyanobacterial Outbreak Upstream in a Reservoir Cascade.

Understanding water quality events in a multiple-impoundment series is important but seldom presented comprehensively. Therefore, this study was conducted to systematically understand the explosion event of geosmin (GSM) in the North Han River (Chuncheon, Soyang, Euiam, and Cheongpyeong Reservoirs) and Han River (Paldang Reservoir), which consists of a cascade reservoir series, the largest drinking water source system in South Korea. We investigated the spatiotemporal relationship of harmful cyanobacterial blooms in the upstream reservoir (Euiam) with the water quality incident event caused by the GSM in the downstream reservoir (Paldang) from January to December 2011. The harmful cyanobacterial bloom occurred during August−September under a high water temperature (>20 °C) after a heavy-rainfall-based flood runoff event. The high chlorophyll-a (Chl-a) concentration in the upper Euiam Reservoir was prolonged for two months with a maximum concentration of 1150.5 mg m−3, in which the filamentous Dolichospermum circinale Kütz dominated the algal community at a rate of >99%. These parameters remarkably decreased (17.3 mg Chl-a m−3) in October 2011 when the water temperature decreased (5 °C) and soluble reactive phosphorus was depleted. However, high and unprecedented GSM concentrations, with a maximum value of 1640 ng L−1, were detected in the downstream reservoirs (Cheongpyeong and Paldang); the level was 11 times higher than the value (10 ng L−1) recommended by the World Health Organization. The concentrations of GSM gradually decreased and had an adverse effect on the drinking water quality until the end of December 2011. Our study indicated that the time lag between the summer−fall cyanobacterial outbreak in the upstream reservoir and winter GSM explosion events in the downstream reservoirs could be attributed to the transport and release of GSM through the effluent from hydroelectric power generation in this multiple-reservoir system. Therefore, we suggest that a structural understanding of the reservoir cascade be considered during water quality management of drinking water sources to avoid such incidents in the future.

Scaling up extractive deacidification of waste cooking oil.

Biodiesel produced from waste feedstocks can play a significant role in fighting climate change, improperly disposed waste and growing energy demand. Waste feedstocks such as used cooking oil have a great potential for energy production. However, they often have to be purified from free fatty acids prior to biodiesel production. Extractive deacidification with deep eutectic solvents is a promising alternative to conventional purification methods. To evaluate the process of extractive deacidification of waste cooking oil, a full set of physical, hydrodynamic and kinetic data were experimentally determined on a laboratory scale. Hydrodynamic and kinetic experiments were performed in three geometrically similar jacketed agitated vessels. Vessels were equipped with axial flow impeller (four pitched blade impeller). Physical properties (density, viscosity and surface tension) were experimentally determined. Preliminary hydrodynamic experiments involved several model systems without mass transfer. As a result, correlation between power number and Reynolds number as well as scale-up criterion was developed. Obtained dependencies were correlated with the physical properties. Mixing intensity for achieving complete dispersion was determined. Second stage of investigation involved two sets of experiments, hydrodynamic and kinetic, with interphase mass transfer (the extraction of free fatty acids from waste cooking oil with deep eutectic solvent, potassium carbonate:ethylene glycol, 1:10). Obtained results enabled understanding interphase mass transfer and prediction of mass transfer coefficient from the derived dimensionless correlations. The values of volumetric mass transfer coefficients were smaller for the dispersed phase, indicating that the prevailing mass transfer resistance was within the droplets. The working hypothesis was that the same process result should be achieved at the same dispersion rate, and that hypothesis was confirmed - at all scales extraction efficiency was 97.9 ± 0.1%.

Hypersaline Pore Water in Gulf of Mexico Beaches Prevented Efficient Biodegradation of Deepwater Horizon Beached Oil.

The 2010 Deepwater Horizon (DWH) blowout released 3.19 million barrels (435 000 tons) of crude oil into the Gulf of Mexico. Driven by currents and wind, an estimated 22 000 tons of spilled oil were deposited onto the northeastern Gulf shorelines, adversely impacting the ecosystems and economies of the Gulf coast regions. In this work we present field work conducted at the Gulf beaches in three U.S. States during 2010-2011: Louisiana, Alabama, and Florida, to explore endogenous mechanisms that control persistence and biodegradation of the MC252-oil deposited within beach sediments as deep as 50 cm. The work involved over 1500 measurements incorporating oil chemistry, hydrocarbon-degrading microbial populations, nutrient and DO concentrations, and intrinsic beach properties. We found that intrinsic beach capillarity along with groundwater depth provides primary controls on aeration and infiltration of near-surface sediments, thereby modulating moisture and redox conditions within the oil-contaminated zone. In addition, atmosphere-ocean-groundwater interactions created hypersaline sediment environments near the beach surface at all the studied sites. The fact that the oil-contaminated sediments retained near or above 20% moisture content and were also eutrophic and aerobic suggests that the limiting factor for oil biodegradation is the hypersaline environment due to evaporation, a fact not reported in prior studies. These results highlight the importance of beach porewater hydrodynamics in generating unique hypersaline sediment environments that inhibited oil decomposition along the Gulf shorelines following DWH.

Hydrodynamics- and hydrochemistry-affected microbial selenate reduction in aquifer: Performance and mechanisms.

Selenate [Se(VI)] with higher content in groundwater will be harmful for human beings. Hence, effective treatment for Se(VI) in aquifer should be conducted reasonably. Microbial reduction of Se(VI) to elemental selenium with weak movability and toxicity has attracted significant attention due to its high efficiency and no secondary contamination. However, hydrodynamic and hydrochemical influences with corresponding mechanisms during Se(VI) bioreduction are still not clear. In this study, influences of flow rate, initial Se(VI) and organic concentrations, coexisting nitrate were evaluated. Se(VI) removal efficiency and capacity reached 96.42 ± 6.82% and 41.28 ± 3.41 (g/m3·d) with flow rate of 0.56 mL/min, initial Se(VI) and chemical organic demand concentrations of 10 mg/L and 400 mg/L. Dechloromonas and Pseudomonas were presumably contributed to Se(VI) reduction, with upregulated serA and tatC genes. Solid Se0 was identified as the final product from Se(VI) reduction. These results will be beneficial for the further comprehending of Se(VI) remediation in aquifer.

Bulk sedimentary phosphorus in relation to organic carbon, sediment textural properties and hydrodynamics in the northern Beibu Gulf, South China Sea.

Bulk sedimentary phosphorus (P) is studied to evaluate its source, distribution, preservation and enrichment in relation with organic carbon (OC), sediment textures and moisture contents in the northern Beibu Gulf. Approximately 80% of surface sediments in the investigated sites were composed of coarse sandy texture (>63 µm). Total P (TP), inorganic P (IP) and organic P (OP) contents were lower to medium range compared to the levels reported for other marginal seas. Sedimentary OC and P were derived from mixed sources, with high terrestrial influence in the coastal areas (molar OC/OP ratios >250:1). The distribution of P corroborated with the variation tendency of fine-grained sediments, moisture contents and OC. Both IP and OP may significantly influence the trophic state of seawater if released from surface sediments. Influenced by hydrodynamics, frequent resuspension and high abundance of sand, TP is less preserved, and shows low to moderate enrichment in surface sediments.

The transcription factor YY2 has less momentous properties of an intrinsically disordered protein than its paralog YY1.

The transcription factor YY2 is a recently discovered paralog of YY1. The two proteins exhibit substantial sequence similarity and partially similar transcriptional activity. They recognize the same DNA sequence in vitro yet bind different promoters in vivo. YY1 comprises two structurally distinct parts: an intrinsically disordered regulatory part and a compact DNA-binding domain. The structure of YY2 is yet unknown. We show that YY2 is structurally similar to YY1, although the conformational state of YY2 is more ordered, as shown by its composition, hydrodynamic properties, spectroscopic signal, and proteolytic susceptibility. As such, YY2's range of molecular partners might be distinct from that of YY1. This could explain different effects of YY1 and YY2 on gene expression patterns and the mechanism of YY proteins in transcriptional regulation.

Spatial distribution of sediment nitrogen and phosphorus in Lake Taihu from a hydrodynamics-induced transport perspective.

Hydrodynamics play an important role in sediment nutrient dynamics in large shallow eutrophic lakes. In this study, the spatial patterns of sediment nitrogen and phosphorus in Lake Taihu were compared from a hydrodynamics-induced transport perspective based on high-resolution investigation of sediment, field observations, numerical simulations and long-term ecological data analysis. The results showed that sediments were primarily distributed in the west and southeast portions of the lake. Additionally, the total nitrogen (TN) and phosphorus (TP) stored in the active sediments was 166,329 t and 67,112.4 t, respectively. The sediment TN content was 319.4-3123.8 mg kg-1, with high content areas being primarily located in the Zhushan, Meiliang and East Taihu bays. The external nitrogen-containing nutrients in the overlying water, which is mostly dissolved nitrogen, can be horizontally transported by lake currents to the water areas with high biomass levels and weak vertical hydrodynamic disturbance where sediment nitrogen enrichment primarily occurs via bio-deposition. The sediment TP content ranged between 382.6 and 1314.1 mg kg-1, and the high content areas were primarily distributed near the inflowing river mouths. Sediment phosphorus enrichment primarily occurred via physical and chemical deposition. Surface waves caused vertical phosphorus transport from sediments to the overlying water but had a limited effect on its spatial distribution. Although the horizontal transport of phosphorus was found to be weaker than that of nitrogen, short-distance vertical transport of sediment phosphorus may relieve nutrient limitations, leading to maintenance of cyanobacterial blooms found in Lake Taihu.

Evaluating physico-chemical influences on cyanobacterial blooms using hyperspectral images in inland water, Korea.

Understanding harmful algal blooms is imperative to protect aquatic ecosystems and human health. This study describes the spatial and temporal distributions of cyanobacterial blooms to identify the relations between blooms and environmental factors in the Baekje Reservoir. Two-year cyanobacterial cell data at one fixed station and four remotely sensed distributions of phycocyanin (PC) concentrations based on hyperspectral images (HSIs) were used to describe the relation between the spatial and temporal variations in the blooms and the affecting factors. An artificial neural network model and a three-dimensional hydrodynamic model were implemented to estimate the PC concentrations using remotely sensed HSIs and simulate the hydrodynamics, respectively. The statistical test results showed that the variations in the cyanobacterial biomass depended significantly on variations in the water temperature (slope = 0.13, p-value < 0.01), total nitrogen (slope = -0.487, p-value < 0.01), and total phosphorus (slope = 20.7, p-value < 0.05), whereas the variation in the biomass was moderately dependent on the variation in the outflow (slope = -0.0097, p-value = 0.065). Water temperature was the main factor affecting variations in the PC concentrations for the three months from August to October and was significantly different for the three months (p-value < 0.01). Hydrodynamic parameters also had a partial effect on the variations in the PC concentrations in those three months. Overall, this study helps to describe spatial and temporal variations in cyanobacterial blooms and identify the factors affecting the variation in the blooms. This study may play an important role as a basis for developing strategies to reduce bloom frequency and severity.

State of the art review and future directions in oil spill modeling.

A review of the state of the art in oil spill modeling, focused on the period from 2000 to present is provided. The review begins with an overview of the current structure of spill models and some lessons learned from model development and application and then provides guiding principles that govern the development of the current generation of spill models. A review of the basic structure of spill models, and new developments in specific transport and fate processes; including surface and subsurface transport, spreading, evaporation, dissolution, entrainment and oil droplet size distributions, emulsification, degradation, and sediment oil interaction are presented. The paper concludes with thoughts on future directions in the field with a primary focus on advancements in handling interactions between Lagrangian elements.

Intrinsic disorder of human Yin Yang 1 protein.

YY1 (Yin Yang 1) is a zinc finger protein with an essential role in various biological functions via DNA- and protein-protein interactions with numerous partners. YY1 is involved in the regulation of a broad spectrum of cellular processes such as embryogenesis, proliferation, tumorigenesis, and snRNA transcription. The more than 100 reported targets of the YY1 protein suggest that it contains intrinsically disordered regions that are involved in such diverse interactions. Here, we present a study of the structural properties of human YY1 using several biochemical and biophysical techniques (fluorescence, circular dichroism, gel filtration chromatography, proteolytic susceptibility) together with various bioinformatics approaches. To facilitate our exploration of the YY1 structure, the full-length protein as well as an N-terminal fragment (residues 1-295) and the C-terminal DNA binding domain were used. We found the N-terminus to be a non-compact fragment of YY1 with little residual secondary structure and lacking a well-defined tertiary structure. The results of our study indicate that YY1 belongs to the family of intrinsically disordered proteins (IDPs), which exist natively in a partially unfolded conformation.

New methodologies to characterize the effectiveness of the gene transfer mediated by DNA-chitosan nanoparticles.

In this work three DNA-chitosan nanoparticle formulations (Np), differing in the molecular weight (MW; 150 kDa, 400 kDa, and 600 kDa) of the polysaccharide, were prepared and administered by two different administration routes: the hydrodynamics-based procedure and the intraduodenal injection. After the hydrodynamic injection, DNA-chitosan nanoparticles were predominantly accumulated in the liver, where the transgene was expressed during at least 105 days. No significant influence of MW was observed on the levels of luciferase expression. The curves of bioluminescence versus time obtained using the charge-coupled device (CCD) camera were described and divided in three phases: (i) the initial phase, (ii) the sustained release step and (iii) the decline phase (promotor inactivation, immunological and physiological processes). From these curves, which describe the transgene expression profile, the behavior of the different formulations as gene delivery systems was characterized. Therefore, the following parameters such as C(max) (maximum level of detected bioluminescence), AUC (area under the bioluminescence-time curve) and MET (mean time of the transgene expression) were calculated. This approach offers the possibility of studying and comparing transgene expression kinetics among a wide variety of gene delivery systems. Finally, the intraduodenal administration of naked DNA permitted the gene transfer in a dose dependent manner quantifiable with the CCD camera within 3 days. Nevertheless, the same administration procedure of the three formulations did not improve the levels of transgene expression obtained with naked DNA. This fact could be explained by the rapid physiological turn-over of enterocytes and by the ability of chitosan nanoparticles to control the DNA release.

Mecanismo de acción local de la ozonoterapia y su combinación con el campo magnético en pacientes con glaucoma primario de ángulo abierto estadio inicial / Mechanism of local action of ozone therapy and its combination with the magnetic field in patients with initial stage primary open-angle glaucoma

En 1989 en el Hospital Carlos J. Finlay se iniciaron estudios en la aplicación del ozono y campo electromagnético en la rehabilitación del paciente portador de glaucoma primario de ángulo abierto con el objetivo de disminuir la presión intraocular y mejorar la función visual y nerviosa deteriorada. Teniendo en cuenta que los resultados obtenidos estuvieron dirigidos fundamentalmente a las alteraciones en la hemodinamia ocular se propuso con este trabajo estudiar el mecanismo de acción de estas técnicas en la hidrodinamia ocular. Se estudiaron 220 pacientes (308 ojos) portadores de glaucoma primario de ángulo abierto estadio inicial, donde se evaluó la función visual y la hidrodinamia ocular. Los resultados en la función visual plantean mejoría en la agudeza visual de un 68 % en los casos tratados con ozono y de un 92 % en la terapia combinada. El campo visual mejoró en el 100 % de los casos. En la hidrodinamia ocular se observó mejoría en ambos esquemas de tratamiento. No hubo variación biológica en los valores de C y F en los esquemas terapéuticos empleados cuando los parámetros hidrodinámicos iniciales fueron normales. La respuesta en la hidrodinamia ocular con las técnicas empleadas fue satisfactoria tanto con el empleo de tratamiento local o sin él. Estas técnicas deben aplicarse en estadio latente de la enfermedad cuando aún no existan manifestaciones clínicas evidentes y no sea necesario el tratamiento local.

Studies on the application of ozone and electromagnetic field in the rehabilitation of the patient carrier of primary open-angle glaucoma were started at "Carlos J. Finlay" Hospital in 1989 aimed at reducing the intraocular pressure and improving the deteriorated visual and nervous function. Taking into account that the results obtained were mainly directed to the alterations in the ocular hemodynamics, we proposed ourselves with this paper to study the mechanism of action of these techniques in the ocular hydrodynamics. 220 patients (308 eyes) carriers of initial stage primary open angle glaucoma were studied. Visual function and ocular hydrodynamics were evaluated among them. The results attained in the visual function showed an improvement of visual acuity of 68 % in the cases treated with ozone, and of 92 % in the combination therapy. The visual field improved in 100 % of the cases. In ocular hydrodynamics, it was observed improvement in both treatment schemes. There was no biological variation in the values of C and F in the therapeutic schemes used when the initial hydrodynamic parameters were normal. The response in the ocular hydrodynamics to the techniques used was satisfactory with local treatment, or without it. These techniques should be applied in the latent stage of the disease even when there are no evident clinical manifestations and the local treatment is not necessary.