Concentrations and sources of polycyclic aromatic hydrocarbons in surface coastal sediments of the northern Gulf of Mexico

Zucheng Wang is with the Department of Geography, Northeast Normal University, Changchun, China. -- Zucheng Wang and Zhanfei Liu are with the Marine Science Institute, The University of Texas at Austin, Port Aransas, TX, USA. -- Kehui Xu is with the Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA – and – the Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, USA. -- Lawrence M Mayer is with the School of Marine Sciences, University of Maine, Walpole, ME, USA. -- Zulin Zhang is with The James Hutton Institute, Aberdeen, UK. -- Alexander S. Kolker is with Louisiana Universities Marine Consortium, Chauvin, LA, USA. -- Wei Wu is with the Department of Coastal Sciences, Gulf Coast Research Laboratory, The University of Southern Mississippi, Ocean Springs, MS, USA.Background: Coastal sediments in the northern Gulf of Mexico have a high potential of being contaminated by petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), due to extensive petroleum exploration and transportation activities. In this study we evaluated the spatial distribution and contamination sources of PAHs, as well as the bioavailable fraction in the bulk PAH pool, in surface marsh and shelf sediments (top 5 cm) of the northern Gulf of Mexico. Results: PAH concentrations in this region ranged from 100 to 856 ng g−1, with the highest concentrations in Mississippi River mouth sediments followed by marsh sediments and then the lowest concentrations in shelf sediments. The PAH concentrations correlated positively with atomic C/N ratios of sedimentary organic matter (OM), suggesting that terrestrial OM preferentially sorbs PAHs relative to marine OM. PAHs with 2 rings were more abundant than those with 5–6 rings in continental shelf sediments, while the opposite was found in marsh sediments. This distribution pattern suggests different contamination sources between shelf and marsh sediments. Based on diagnostic ratios of PAH isomers and principal component analysis, shelf sediment PAHs were petrogenic and those from marsh sediments were pyrogenic. The proportions of bioavailable PAHs in total PAHs were low, ranging from 0.02% to 0.06%, with higher fractions found in marsh than shelf sediments. Conclusion: PAH distribution and composition differences between marsh and shelf sediments were influenced by grain size, contamination sources, and the types of organic matter associated with PAHs. Concentrations of PAHs in the study area were below effects low-range, suggesting a low risk to organisms and limited transfer of PAHs into food web. From the source analysis, PAHs in shelf sediments mainly originated from direct petroleum contamination, while those in marsh sediments were from combustion of fossil fuels.Marine [email protected]

Directly growing hierarchical nickel-copper hydroxide nanowires on carbon fibre cloth for efficient electrooxidation of ammonia

Ammonia is an attractive carbon-free chemical for electrochemical energy conversion and storage. However, the sluggish kinetic rates of the ammonia electrooxidation reaction, and high cost and poisoning of Pt-based catalysts still remain challenges. This also limits the development of direct ammonia fuel cells. In this work, we directly grew hierarchical mixed NiCu layered hydroxides (LHs) nanowires on carbon fibre cloth electrodes by a facile one-step hydrothermal synthesis method for efficient electro-oxidation of ammonia. This catalyst achieves a current density of 35 mA cm−2 at 0.55 V vs. Ag/AgCl, which is much higher than that of bare Ni(OH)2 catalyst (5 mA cm−2). This is due to abundant active sites and a synergistic effect between Ni and Cu, possibly due to the formation of Ni1−xCuxOOH on the surface of the catalysts through the electrochemical activation of the mixture of Cu(OH)2 and α-Ni(OH)2. In the investigated first row transition elements, it is found that Cu is the sole first-row transition metal to effectively improve activity of Ni(OH)2 for ammonia electrooxidation. This mixed NiCu LHs nano-wire catalyst outperforms commercial Pt/C catalyst in the aspects of ammonia oxidation current and stability, demonstrating it to be a promising low-cost and stable catalyst for efficient ammonia electrooxidation in alkaline condition, which is a potential electrode for ammonia fuel cells for power generation or electrolysis of ammonia for ammonia-containing wastewater treatment

Susceptibility of schizophrenia and affective disorder not associated with loci on chromosome 6q in Han Chinese population

<p>Abstract</p> <p>Background</p> <p>Several linkage studies across multiple population groups provide convergent support for susceptibility loci for schizophrenia – and, more recently, for affective disorder – on chromosome 6q. We explore whether schizophrenia and affective disorder have common susceptibility gene on 6q in Han Chinese population.</p> <p>Methods</p> <p>In the present study, we genotyped 45 family trios from Han Chinese population with mixed family history of schizophrenia and affective disorder. Twelve short tandem repeat (STRs) markers were selected, which covered 102.19 cM on chromosome 6q with average spacing 9.29 cM and heterozygosity 0.78. The transmission disequilibrium test (TDT) was performed to search for susceptibility loci to schizophrenia and affective disorder.</p> <p>Results</p> <p>The results showed STRs D6S257, D6S460, D6S1021, D6S292 and D6S1581 were associated with susceptibility to psychotic disorders. When families were grouped into schizophrenia and affective disorder group, D6S257, D6S460 and D6S1021, which map closely to the centromere of chromosome 6q, were associated with susceptibility to schizophrenia. Meanwhile, D6S1581, which maps closely to the telomere, was associated with susceptibility to affective disorder. But after correction of multiple test, all above association were changed into no significance (P > 0.05).</p> <p>Conclusion</p> <p>These results suggest that susceptibility of schizophrenia and affective disorder not associated with loci on chromosome 6q in Han Chinese population.</p

Electrodeposited NiCu bimetal on carbon paper as stable non-noble anode for efficient electrooxidation of ammonia

Electrochemical remediation of ammonia-containing wastewater at low cell voltage is an energy-effective technology which can simultaneously recover energy via hydrogen evolution reaction. One of the main challenges is to identify a robust, highly active and inexpensive anode for ammonia electrooxidation. Here we present an alternative anode, prepared by electrochemical co-deposition of Ni and Cu onto carbon paper. This NiCu bimetallic catalyst is characterised by scanning electron microscope, scanning transmission electron microscope, X-ray diffraction, x-ray photoelelectron spectroscopy, cyclic voltammetry, linear sweep voltammetry and chronoamperometry techniques. The stability and activity of NiCu bimetallic catalyst are largely improved in comparison with Ni or Cu catalyst. Moreover this noble-metal-free NiCu catalyst even performs better than Pt/C catalyst, as NiCu is not poisoned by ammonia. An ammonia electrolysis cell is fabricated with NiCu/carbon paper as anode for ammonia electrolysis. The influences of pH value, applied cell voltages and initial ammonia concentration on cell current density, ammonia removal and energy efficiency are tested. An ammonia removal efficiency of ∼80% and coulombic efficiency up to ∼92% have been achieved. Ni-Cu bimetal on carbon paper is a stable non-noble anode for efficient electrooxidation of ammonia

Development of acillary techniques for chromatographic analysis of trace organic pollutants in environmental samples

published_or_final_versionChemistryDoctoralDoctor of Philosoph

Recent progress in electrocatalysts with mesoporous structures for application in polymer electrolyte membrane fuel cells

Recently mesoporous materials have drawn great attention in fuel cell related applications, such as preparation of polymer electrolyte membranes and catalysts, hydrogen storage and purification. In this mini-review, we focus on recent developments in mesoporous electrocatalysts for polymer electrolyte membrane fuel cells, including metallic and metal-free catalysts for use as either anode or cathode catalysts. Mesoporous Pt-based metals have been synthesized as anode catalysts with improved activity and durability. Mesoporous carbons together with other inorganic materials are better supporting materials than conventional carbon black, which have a large surface area, high porosity and synergistic effect with metal particles. Pt supported on these materials has a small particle size, uniform distribution and good access to fuels, which performs better as fuel cell catalysts than commercial Pt/C. Some efforts such as further improvement in the conductivity and chemical stability of mesoporous carbon by chemical doping are stated. Moreover, metal free cathode catalysts based on heteroatom modified mesoporous carbon are also summarized

Minimizing the Health Risks from Hydrocarbon Contaminated Soils by Using Electric Field-Based Treatment for Soil Remediation

The present work addresses the assessment of human health risk from soil contaminated with total petroleum hydrocarbons (TPHs) due to crude oil pollution, with a particular focus on the polycyclic aromatic hydrocarbon (PAH) group of carcinogenic and toxic substances. Given that the measured risk for human health exceeded the accepted level, the study considered an electrochemical remediation method. The laboratory-scale experiments were conducted by using an electric field-based treatment as a possible solution for the remediation of contaminated soil. After 20 days of treatment, while the voltage applied was 15 V (specific voltage of 1 V/cm), the hydrocarbon content was significantly reduced. The parameters measured to determine the overall remediation efficiency were pH, redox potential, ionic strength, soil characteristics, voltage gradient, and zeta potential. The remediation degree observed during the experiments was around 50% for TPHs and 46% for PAHs. The applied remediation method resulted in significant removal efficiency of the tested contaminants from the soil. Consequently, the human health risk assessment for the new degree of contaminants in the soil was achieved. This data demonstrated to what extent the application of the remediation applied technology ensured an acceptable risk under the same exposure conditions for the industrial workers