Spatial structure of internal Poincaré waves in Lake Michigan

In this paper we examine the characteristics of near-inertial internal Poincaré waves in Lake Michigan (USA) as discerned from field experiments and hydrodynamic simulations. The focus is on the determination of the lateral and vertical structure of the waves. Observations of near-inertial internal wave properties are presented from two field experiments in southern Lake Michigan conducted during the years 2009 and 2010 at Michigan City (IN, USA) and Muskegon (MI, USA), respectively. Spectra of thermocline displacements and baroclinic velocities show that kinetic and potential baroclinic energy is dominated by near-inertial internal Poincaré waves. Vertical structure discerned from empirical orthogonal function analysis shows that this energy is predominantly vertical mode 1. Idealized hydrodynamic simulations using stratifications from early summer (June), mid-summer (July) and fall (September) identify the basin-scale internal Poincaré wave structure as a combination of single- and two-basin cells, similar to those identified in Lake Erie by Schwab, with near-surface velocities largest in the center of the northern and southern basins. Near-inertial bottom kinetic energy is seen to have roughly constant magnitude over large swathes across the basin, with higher magnitude in the shallower areas like the Mid-lake Plateau, as compared with the deep northern and southern basins. The near-bottom near-inertial kinetic energy when mapped appears similar to the bottom topography map. The wave-induced vertical shear across thermocline is concentrated along the longitudinal axis of the lake basin, and both near-bottom velocities and thermocline shear are reasonably explained by a simple conceptual model of the expected transverse variability.     

Microplastic sources,formation, toxicity and remediation: a review

Microplastic pollution is becoming a major issue for human health due to the recent discovery of microplastics in most ecosystems. Here, we review the sources, formation, occurrence, toxicity and remediation methods of microplastics. We distinguish ocean-based and land-based sources of microplastics. Microplastics have been found in biological samples such as faeces, sputum, saliva, blood and placenta. Cancer, intestinal, pulmonary, cardiovascular, infectious and inflammatory diseases are induced or mediated by microplastics. Microplastic exposure during pregnancy and maternal period is also discussed. Remediation methods include coagulation, membrane bioreactors, sand filtration, adsorption, photocatalytic degradation, electrocoagulation and magnetic separation. Control strategies comprise reducing plastic usage, behavioural change, and using biodegradable plastics. Global plastic production has risen dramatically over the past 70 years to reach 359 million tonnes. China is the world's top producer, contributing 17.5% to global production, while Turkey generates the most plastic waste in the Mediterranean region, at 144 tonnes per day. Microplastics comprise 75% of marine waste, with land-based sources responsible for 80–90% of pollution, while ocean-based sources account for only 10–20%. Microplastics induce toxic effects on humans and animals, such as cytotoxicity, immune response, oxidative stress, barrier attributes, and genotoxicity, even at minimal dosages of 10 μg/mL. Ingestion of microplastics by marine animals results in alterations in gastrointestinal tract physiology, immune system depression, oxidative stress, cytotoxicity, differential gene expression, and growth inhibition. Furthermore, bioaccumulation of microplastics in the tissues of aquatic organisms can have adverse effects on the aquatic ecosystem, with potential transmission of microplastics to humans and birds. Changing individual behaviours and governmental actions, such as implementing bans, taxes, or pricing on plastic carrier bags, has significantly reduced plastic consumption to 8–85% in various countries worldwide. The microplastic minimisation approach follows an upside-down pyramid, starting with prevention, followed by reducing, reusing, recycling, recovering, and ending with disposal as the least preferable option.

     

One-step synthesis of N-doped metal/biochar composite using NH3-ambiance pyrolysis for efficient degradation and mineralization of Methylene Blue

A series of new biochar-supported composite based on the combination of biochar and metallic nanoparticles(NPs)were produced through single-step pyrolysis of FeCl_3–Ti(OBu)_4 laden agar biomass under NH_3 environment.The physiochemical properties of composites were characterized thoroughly.It has found that heating temperature and N-doping through NH_3-ambiance pyrolysis significantly influence the visible-light sensitivity and bandgap energy of composites.The catalytic activities of composites were measured by degradation of Methylene Blue(MB)in the presence or absence of H_2O_2 and visible-light irradiation.Our best catalyst(N–TiO_2–Fe_3O_4-biochar)exhibits rapid and high MB removal competency(99.99%)via synergism of adsorption,photodegradation,and Fenton-like reaction.Continuous production of O_2U~-and UOH radicles performs MB degradation and mineralization,confirmed by scavenging experiments and degradation product analysis.The local trap state Ti~(3+),Fe_3O_4,and N-carbon of the catalyst acted as active sites.It has suggested that the Ti~(3+)and N-doped dense carbon layer improve charge separation and shuttle that prolonged photo-Fenton like reaction.Moreover,the catalyst is highly stable,collectible,and recyclable up to 5 cycles with high MB degradation efficiency.This work provides a new insight into the synthesis of highly visible-light sensitized biocharsupported photocatalyst through NH_3-ambiance pyrolysis of NPs-laden biomass.     

The rhetoric of participation re-examined: The state,NGOs and water users at Varanasi,Uttar Pradesh,India

Summary People's participation is usually regarded as a sine qua non for the success and sustainability of development projects. Yet in practice, it raises a number of questions. Who are the people? Why is their participation sought, and how or at what level, is such participation desired? This paper seeks to examine the rhetoric of participation in the implementation of the Ganga Action Plan (GAP) at Varanasi, in the north-eastern State of Uttar Pradesh, India. Launched in 1985, the GAP is the first major attempt to systematically control and monitor the pollution of a significant river in the country. In addition, it claimed to be a people's programme because of the powerful and deep-seated cultural and religious meaning associated with the Ganga. Varanasi, however, is indicative of its failure to deliver this promise — the GAP is only acceptable to authority because it does not challenge the existing institutional order, and its participatory content is symbolic rather than substantive. Non-govemental organisations, traditionally viewed as intermediary actors between the micro and macro levels, work within the socio-political framework of the city. In the process, water-user groups such as the washermen who derive an economic livelihood from washing clothes in the Ganga, are literally excluded from the definition and process of participation.She obtained her PhD, the basis of the current research, at the University of Cambridge, UK.     

Correlation between oxygen utilization and electron transport activity in marine phytoplankton

Measurement of a respiratory control ratio is deemed very useful in determination of energy balance in respiration. We have defined and computed a control ratio as the ratio of the rate of oxygen consumption in vivo to the calculated maximum rate of oxygen consumption in vitro as measured by enzymatic electron transport rates. In order for a control ratio to serve a useful purpose in calculating in situ oxygen consumption in a water parcel, the ratio must be fairly constant. Our results indicated that this is precisely so in healthy cultures of the 9 species of phytoplankton studied. The data presented in this communication further point towards the potential for making reasonable estimates of phytoplankton oxygen consumption in an ocean water parcel by directly utilizing in vitro electron transport activity measurements.     

Prenatal diagnosis of familial ring 21 chromosome

Ring chromosome 21 is a rare chromosome anomaly often associated with mental retardation and dysmorphic features. Less commonly, the ring chromosome can be familial and associated with a normal phenotype. Phenotypically normal female carriers, however, are at increased risk of having children with Down syndrome, mosaic monosomy 21, and variable duplication or deletion of chromosome 21. Because of the relative mitotic and meiotic instability of ring chromosomes, abnormal cytogenetic findings encountered during prenatal diagnosis may not reflect the true genetic status of the fetus. This is a report of a phenotypically normal female carrier of a familial ring 21 chromosome. Prenatal diagnosis on her twin pregnancy revealed a mosaic 46,XX,r(21)(p13;q22) (77 per cent)/45,XX, – 21 in one fetus and a normal male karyotype in the second. The pregnancy was carried to term. Both infants are completely normal, with a non-mosaic ring 21 karyotype from the lymphocytes of one twin. The diagnostic uncertainty and problematic genetic counselling related to fetal cytogenetic abnormalities are the subjects of this report.     

Method for evaluation of immunotoxicity of dioxin compounds using human T-lymphoblastic cell line, L-MAT

Caspase-3 was activated in apoptotic L-MAT cells by treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Treatment with tributyltin, which has been reported to induce apoptosis in rat thymocytes, also activated caspase-3 and led to cell death in L-MAT cells. Blocking caspase-3 activity with the peptide inhibitor, DEVE-CHO, prevented TCDD from inducing subsequent apoptotic changes. The potent Ah receptor ligand, 2,3,7,8-tetrachlorodibenzofuran (TCDF), the low acute toxicity compound, 1,2,3,4,6,7,9-heptachlorodibenzo-p-dioxin (HCDD), and one of the major contaminants in human milk, 3,3',4,4',5-pentachlorobiphenyl (PCBP), increased the activation level of caspase-3, each in a dose-dependent manner. Thus, we propose that measuring caspase-3 activation in the human T-lymphoblastic cell line, L-MAT, is a useful evaluation method for the immunotoxicity of dioxin compounds.     

Secondary imbibition in NAPL-invaded mixed-wet sediments

A previously developed pore network model is used here to study the spontaneous and forced secondary imbibition of a NAPL-invaded sediment, as in the displacement of NAPL by waterflooding a mixed-wet soil. We use a 3D disordered pore network with a realistic representation of pore geometry and connectivity, and a quasi-static displacement model that fully describes the pore-scale physics. After primary drainage (NAPL displacing water) up to a maximum capillary pressure, we simulate secondary imbibition (water displacing NAPL). We conduct a parametric study of imbibition by varying systematically the controlling parameters: the advancing contact angles, the fraction of NAPL-wet pores, the interfacial tension, and the initial water saturation. Once the secondary imbibition is completed, the controlling displacement mechanisms, capillary pressures, relative permeabilities, and trapped NAPL saturations are reported. It is assumed that NAPL migrates into an initially strongly water-wet sediment, i.e., the receding contact angles are very small. However, depending on the surface mineralogy and chemical compositions of the immiscible fluid phases, the wettability of pore interiors is altered while the neighborhoods of pore corners remain strongly water-wet-resulting in a mixed-wet sediment. Here, we compare three different levels of wettability alteration: water-wet (advancing contact angles (20 degrees to 55 degrees), intermediate-wet (55 degrees to 120 degrees), and NAPL-wet (120 degrees to 155 degrees). The range of advancing contact angles and the fraction of NAPL-wet pores have dramatic effects on the NAPL-water capillary pressures and relative permeabilities. The spatially inhomogeneous interfacial tension has a minor impact on the trapped NAPL saturation and relative permeability to NAPL, and a slight effect on the relative permeability to water. The initial water saturation has a slight effect on the two-phase flow characteristics of water-wet sediments; however, with more NAPL-wet pores in the sediment, it starts to have a profound effect on the water and NAPL relative permeabilities.