Ionic Liquid-Based Quartz Crystal Microbalance Sensors for Organic Vapors: A Tutorial Review

Organic vapor sensors are used in diverse applications ranging from environmental monitoring to biomedical diagnostics. Among a number of these sensors, quartz crystal microbalance (QCM) sensors prepared by coating ionic liquids (ILs) or their composites are promising devices for the analysis of volatile organic compounds (VOCs) in complex chemical mixtures. Ionic liquids are remarkable materials, which exhibit tunable physico-chemical properties, chemical and thermal stability, multiple interactions with diverse group of molecules, and enormous structural variability. Moreover, ILs exhibit viscoelastic properties, and hence these materials are ideal for creation of QCM virtual sensor arrays. While the scientific literature on IL-coated QCM sensors is rapidly growing, there is still much to learn. This manuscript provides a comprehensive review on the development of IL-coated QCM sensors and multi-sensor arrays as well as their applications for the analysis of VOCs in complex mixtures. Furthermore, IL-coated QCM virtual sensor arrays and their applications are presented. A short overview of some of the QCM designs, future research areas, and recommendations are also discussed. This short review is a necessary first step towards standardization and further development of QCM for the analysis of VOCs

Distributions and Accumulation Rates of Polycyclic Aromatic Hydrocarbons in the Northern Gulf of Mexico Sediments

Sediment samples collected from shelf, slope and interior basin of the northern Gulf of Mexico during 2011–2013, 1–3 years after the Deepwater Horizon (DWH) oil spill, were utilized to characterize PAH pollution history, in this region. Results indicate that the concentrations of surface ΣPAH43 and their accumulation rates vary between 44 and 160 ng g−1 and 6–55 ng cm−2 y−1, respectively. ΣPAH43 concentration profiles, accumulation rates and Δ14C values are significantly altered only for the sediments in the immediate vicinity of the DWH wellhead. This shows that the impact of DWH oil input on deep-sea sediments was generally limited to the area close to the spill site. Further, the PAHs source diagnostic analyses suggest a noticeable change in PAHs composition from higher to lower molecular weight dominance which reflects a change in source of PAHs in the past three years, back to the background composition. Results indicate low to moderate levels of PAH pollution in this region at present, which are unlikely to cause adverse effects on benthic communities

Agroforestry for mountain development: Prospects, challenges and ways forward in Nepal

Most of the agroforestry systems (AFS) in Nepal are traditional, and deliberate management of trees, crops and livestock as an integrated and interactive agroecosystem, albeit its enormous socio-economic and ecological benefits, is limited. The objective of this review paper is to understand the prospects, analyze challenges and suggest practical solution for promoting agroforestry as a viable system balancing economic, social and environmental concerns. We develop this paper based on practical experience on the ground and an in-depth review of relevant literature and highlights the prospects, challenges and ways forward of AFS, both farm-based and forest-based, in Nepal. Nepal has enormous agroecological diversity, suitable land availability for agroforestry, traditional knowledge, skill and labor forces, and huge prospects of adapting new technologies and developing market systems, especially considering emerging markets for developing remunerative and environment friendly value chains. However, the prospective value chains of the mountain agroforestry products face many challenges, including i) socio-economic constraints of the farmers mainly because of high initial adoption costs, limited information on benefit-cost of agroforestry practices, limited knowledge on full benefits of agroforestry, and limited markets and marketing information; ii) institutional constraints because of unclear policy to support agroforestry, the lack of extension services and undefined administrative boundaries; and iii) inadequate scientific knowledge, expertise and technologies to address management complexity of agroforestry system. We therefore suggest having a scan of those challenges and find out solutions, especially for promoting growth and competitiveness of the sector with poverty reduction strategy ensuring availability of food, fuel, fodder and employment opportunity for local communities. The paper provides a few successful cases of AFS and finally suggests ways forward to promote AFS and a business model which could help achieve the untapped potentials for enhancing income and employment opportunity, achieving food and nutrition security, and building sustainable land use systems

Correction: Coupled effects of oil spill and hurricane on saltmarsh terrestrial arthropods.

[This corrects the article DOI: 10.1371/journal.pone.0194941.]

Weathering of Oil Spilled in the Marine Environment

Crude oil is a complex mixture of many thousands of mostly hydrocarbon and nitrogen-, sulfur-, and oxygen-containing compounds with molecular weights ranging from below 70 Da to well over 2,000 Da. When this complex mixture enters the environment from spills, ruptures, blowouts, or seeps, it undergoes a continuous series of compositional changes that result from a process known as weathering. Spills of petroleum involving human activity generally result in more rapid input of crude oil or refined products (diesel, gasoline, heavy fuel oil, and diluted bitumens) to the marine system than do natural processes and urban runoffs. The primary physicochemical processes involved in weathering include evaporation, dissolution, emulsification, dispersion, sedimentation/flocculation, microbial degradation, and photooxidation

Weathering of Oil Spilled in the Marine Environment

Crude oil is a complex mixture of many thousands of mostly hydrocarbon and nitrogen-, sulfur-, and oxygen-containing compounds with molecular weights ranging from below 70 Da to well over 2,000 Da. When this complex mixture enters the environment from spills, ruptures, blowouts, or seeps, it undergoes a continuous series of compositional changes that result from a process known as weathering. Spills of petroleum involving human activity generally result in more rapid input of crude oil or refined products (diesel, gasoline, heavy fuel oil, and diluted bitumens) to the marine system than do natural processes and urban runoffs. The primary physicochemical processes involved in weathering include evaporation, dissolution, emulsification, dispersion, sedimentation/flocculation, microbial degradation, and photooxidation

Coupled effects of oil spill and hurricane on saltmarsh terrestrial arthropods

<div><p>Terrestrial arthropods play an important role in saltmarsh ecosystems, mainly affecting the saltmarsh’s primary production as the main consumers of terrestrial primary production and decomposition. Some of these arthropods, including selected insects and spiders, can be used as ecological indicators of overall marsh environmental health, as they are differentially sensitive to ecological stressors, such as land loss, erosion, oil spills, and tropical storms. In the present study, we used terrestrial arthropods collected from seven (three lightly-oiled, four heavily-oiled) sites in Barataria Bay and from three unoiled reference sites in Delacroix, Louisiana, to determine the impacts of the distribution and re-distribution of <i>Deepwater Horizon</i> (DWH) oil on these saltmarsh ecosystems. A total of 9,476 and 12,256 insects were collected in 2013 and 2014, respectively. The results show that the terrestrial arthropods were negatively affected by the re-distribution of DWH oil by Hurricane Isaac in 2012, although the level of impacts varied among the arthropod groups. Moreover, the mean diversity index was higher (>1.5) in 2014 than in 2013 (<1.5) for all sites, suggesting a recovery trajectory of the saltmarsh arthropod population. The higher taxonomic richness observed in the reference sites compared to the oiled sites for both years also indicated long-term impacts of DWH oil to the saltmarsh arthropod community. Whereas a slow recovery of certain terrestrial arthropods was observed, long-term monitoring of arthropod communities would help better understand the recovery and succession of the marsh ecosystems.</p></div

Effect of treatment (heavily oil, lightly oiled, and reference), year (2013 and 2014) and their interaction (treatment*year) on the insects and spider (p values).

<p>The degree of freedom for treatment (df = 7), year (df = 47) and treatment*year interaction (df = 47) is same for all the arthropods.</p

Geographic coordinates for the treatment sites: heavily oiled, lightly oiled and reference sites.

<p>Geographic coordinates for the treatment sites: heavily oiled, lightly oiled and reference sites.</p

Mean (±SE) abundance of individual group of arthropods collected per sweep net sample in reference, light oiled and heavily oiled sites in 2013 (blue) and 2014 (orange).

<p>Mean (±SE) abundance of individual group of arthropods collected per sweep net sample in reference, light oiled and heavily oiled sites in 2013 (blue) and 2014 (orange).</p