32 research outputs found
Current State of Microplastic Pollution Research Data: Trends in Availability and Sources of Open Data
The rapid growth in microplastic pollution research is influencing funding priorities, environmental policy, and public perceptions of risks to water quality and environmental and human health. Ensuring that environmental microplastics research data are findable, accessible, interoperable, and reusable (FAIR) is essential to inform policy and mitigation strategies. We present a bibliographic analysis of data sharing practices in the environmental microplastics research community, highlighting the state of openness of microplastics data. A stratified (by year) random subset of 785 of 6,608 microplastics articles indexed in Web of Science indicates that, since 2006, less than a third (28.5%) contained a data sharing statement. These statements further show that most often, the data were provided in the articlesâ supplementary material (38.8%) and only 13.8% via a data repository. Of the 279 microplastics datasets found in online data repositories, 20.4% presented only metadata with access to the data requiring additional approval. Although increasing, the rate of microplastic data sharing still lags behind that of publication of peer-reviewed articles on environmental microplastics. About a quarter of the repository data originated from North America (12.8%) and Europe (13.4%). Marine and estuarine environments are the most frequently sampled systems (26.2%); sediments (18.8%) and water (15.3%) are the predominant media. Of the available datasets accessible, 15.4% and 18.2% do not have adequate metadata to determine the sampling location and media type, respectively. We discuss five recommendations to strengthen data sharing practices in the environmental microplastic research community
A synthesis of three decades of hydrological research at Scotty Creek, NWT, Canada
Scotty Creek, Northwest Territories (NWT), Canada, has
been the focus of hydrological research for nearly three decades. Over this
period, field and modelling studies have generated new insights into the
thermal and physical mechanisms governing the flux and storage of water in
the wetland-dominated regions of discontinuous permafrost that characterises
much of the Canadian and circumpolar subarctic. Research at Scotty Creek
has coincided with a period of unprecedented climate warming, permafrost
thaw, and resulting land cover transformations including the expansion of
wetland areas and loss of forests. This paper (1)Â synthesises field and
modelling studies at Scotty Creek, (2)Â highlights the key insights of these
studies on the major water flux and storage processes operating within and
between the major land cover types, and (3)Â provides insights into the rate
and pattern of the permafrost-thaw-induced land cover change and how such
changes will affect the hydrology and water resources of the study region.</p
There is no such thing as âundisturbedâ soil and sediment sampling: sampler-induced deformation of salt marsh sediments revealed by 3D X-ray computed tomography
Purpose: Within most environmental contexts, the collection of 'undisturbed' samples is widely relied-upon in studies of soil and sediment properties and structure. However, the impact of sampler-induced disturbance is rarely acknowledged, despite the potential significance of modification to sediment structure for the robustness of data interpretation. In this study, 3D-computed X-ray microtomography (ÎŒCT) is used to evaluate and compare the disturbance imparted by four commonly-used sediment sampling methods within a coastal salt-marsh.
Materials and methods: Paired sediment core samples from a restored salt-marsh at Orplands Farm, Essex, UK were collected using four common sampling methods (push, cut, hammer and gouge methods). Sampling using two different area-ratio cores resulted in a total of 16 cores that were scanned using 3D X-Ray computed tomography, to identify and evaluate sediment structural properties of samples that can be attributed to sampling method.
Results and discussion: 3D qualitative analysis identifies a suite of sampling-disturbance structures including gross-scale changes to sediment integrity and substantial modification of pore-space, structure and distribution, independent of sediment strength and stiffness. Quantitative assessment of changes to pore-space and sediment density arising from the four sampling methods offer a means of direct comparison between the impact of depth-sampling methods. Considerable disturbance to samples result from use of push, hammer and auguring samplers, whilst least disturbance is found in samples recovered by cutting and advanced trimming approaches.
Conclusions: It is evident that with the small-bore tubes and samplers commonly used in environmental studies, all techniques result in disturbance to sediment structure to a far greater extent than previously reported, revealed by ÎŒCT. This work identifies and evaluates for the first time the full nature, extent and significance of internal sediment disturbance arising from common sampling methods
Bacterial Stern layer diffusion: experimental determination with spectral induced polarization and sensitivity to nitrite toxicity
Spectral induced polarization signatures have been used as proxies for microbial abundance in subsurface environments, by taking advantage of the charged properties of microbial cell membranes. The method's applicability, however, remains qualitative, and signal interpretation ambiguous. The adoption of spectral induced polarization as a robust geoâmicrobiological tool for monitoring microbial dynamics in porous media requires the development of quantitative relationships between biogeochemical targets and spectral induced polarization parameters, such as biomass density and imaginary conductivity (Ïâł). Furthermore, deriving cell density information from electrical signals in porous media necessitates a detailed understanding of the nature of the cell membrane surface charge dynamics. We present results from a fully saturated sandâfilled column reactor experiment where Shewanella oneidensis growth during nitrate reduction to ammonium was monitored using spectral induced polarization. While our results further confirm the direct dependence of Ïâł on changing cell density, ColeâCole derived relaxation times also record the changing surface charging properties of the cells, ascribed to toxic stress due to nitrite accumulation. Concurrent estimates of cell size yield the first measurementâderived estimation of the apparent surface ion diffusion coefficient for cells (Ds = 5.4 ±1.3 ”m2 sâ1), strengthening the link between spectral induced polarization and electrochemical cell polarization. Our analysis provides a theoretical framework on which to build Ïâłâcell density relations using benchâscale experiments, leading to eventual robust nonâdestructive monitoring of in situ microbial growth dynamics.Canada Excellence Research Chair programmeWaterlooâTechnion University Cooperation Programm
Outstanding supercapacitor performance of nd-mn co-doped perovskite lafeo3@nitrogen-doped graphene oxide nanocomposites
Perovskites have been significantly considered as promising materials for electrochemical energy storage in the recent years. Co-doping of Mn and Nd with hydrothermally synthesized LaFeO3 (LF) perovskite resulted in La0.8Nd0.2Fe0.8Mn0.2O3 (LNFM) with significantly higher specific capacitance of 158 F/g at 50 mV/s compared to non-doped and single doped LF samples. Subsequently, LNFM/nitrogen-doped graphene oxide (NGO) nanocomposite was prepared and investigated. It was found out that the introducing of NGO substantially enhances the specific capacitance of the nanocomposite up to 1060 F/g at 50 mV/s. Besides, the composite revealed outstanding capacity retention as 92.4% after 10000 continuous cycle (85.37% for the LNFM sample). In overall, the electrochemical behavior of the composite with 1:1 ratio of LNFM/NGO confirms its high potential as supercapacitor for energy storage applications
Comparison of light transmission and reflection techniques to determine concentrations in flow tank experiments
Transmissive and reflective intensity measurements for visual concentration determinations in 2D flow tank experiments were compared and evaluated for their applicability in the study of flow and transport phenomena. A density-dependent heterogeneous flow experiment was conducted and transmission and reflection images of the dyed saltwater plume were analyzed. A single light source and dark curtains forced the light to pass through the porous media only, thus facilitating the transmission measurements. The reflection images delivered a more homogeneous spatial illumination than the transmission images. Major perturbations of the transmission images were lens flare effects and light dispersion within the bead-water-Plexiglas system which smear the front of the plume. Based on the conducted evaluation of transmissive and reflective intensity measurements, the reflection data delivered more reliable intensity values to derive solute concentrations in intermediate scale flow tank experiments
Linking Spectral Induced Polarization (SIP) and Subsurface Microbial Processes: Results from Sand Column Incubation Experiments
Geophysical techniques, such as spectral
induced polarization (SIP),
offer potentially powerful approaches for in situ monitoring of subsurface
biogeochemistry. The successful implementation of these techniques
as monitoring tools for reactive transport phenomena, however, requires
the deconvolution of multiple contributions to measured signals. Here,
we present SIP spectra and complementary biogeochemical data obtained
in saturated columns packed with alternating layers of ferrihydrite-coated
and pure quartz sand, and inoculated with <i>Shewanella oneidensis</i> supplemented with lactate and nitrate. A biomass-explicit diffusion-reaction
model is fitted to the experimental biogeochemical data. Overall,
the results highlight that (1) the temporal response of the measured
imaginary conductivity peaks parallels the microbial growth and decay
dynamics in the columns, and (2) SIP is sensitive to changes in microbial
abundance and cell surface charging properties, even at relatively
low cell densities (<10<sup>8</sup> cells mL<sup>â1</sup>). Relaxation times (Ï) derived using the ColeâCole
model vary with the dominant electron accepting process, nitrate or
ferric iron reduction. The observed range of Ï values, 0.012â0.107
s, yields effective polarization diameters in the range 1â3
ÎŒm, that is, 2 orders of magnitude smaller than the smallest
quartz grains in the columns, suggesting that polarization of the
bacterial cells controls the observed chargeability and relaxation
dynamics in the experiments