Site-specific Sampling Research Articles

Breaking barriers in passive sampling: The potential of PTFE membranes in the monitoring of hydrophilic micropollutants

Passive samplers are key tools to sample hydrophilic micropollutants in water. Two main approaches address the influence of hydrodynamics: (1) determining site-specific sampling rate (RS) by characterizing kw, the mass transfer coefficient of the water-boundary layer (WBL), and (2) reducing WBL impact using a diffusive material to control the uptake. The first requires calibration data and the second has only been achieved using fragile diffusive material. This study assesses the transfer of hydrophilic contaminants through polytetrafluoroethylene (PTFE; 30 µm thick), a new membrane material with lower sorption than commonly used polyethersulfone (PES). Combined for the first time in a Chemcatcher-like configuration, we calibrated the modified samplers for 44 micropollutants to provide RS – kw relationships for in-situ RS determination (approach 1). Micropollutants accumulated over 2000 times more on the sorbent than on PTFE. PTFE-based RS (0.027 to 0.300 L day-1) were 2.5 higher than previously reported with PES. Membrane property measurements (porosity, tortuosity) indicated that accumulation is primarily controlled by the membrane. Extrapolation indicated that using thicker PTFE membranes (≥ 100 µm) would shift uptake control entirely to the membrane in river conditions (approach 2). This finding could enable RS prediction based on contaminants properties, thus representing a significant advancement in passive sampling.

Individual genotypes from environmental DNA: Fingerprinting snow tracks of three large carnivore species.

Continued advancements in environmental DNA (eDNA) research have made it possible to access intraspecific variation from eDNA samples, opening new opportunities to expand non-invasive genetic studies of wildlife populations. However, the use of eDNA samples for individual genotyping, as typically performed in non-invasive genetics, still remains elusive. We present successful individual genotyping of eDNA obtained from snow tracks of three large carnivores: brown bear (Ursus arctos), European lynx (Lynx lynx) and wolf (Canis lupus). DNA was extracted using a protocol for isolating water eDNA and genotyped using amplicon sequencing of short tandem repeats (STR), and for brown bear a sex marker, on a high-throughput sequencing platform. Individual genotypes were obtained for all species, but genotyping performance differed among samples and species. The proportion of samples genotyped to individuals was higher for brown bear (5/7) and wolf (7/10) than for lynx (4/9), and locus genotyping success was greater for brown bear (0.88). The sex marker was typed in six out of seven brown bear samples. Results for three species show that reliable individual genotyping, including sex identification, is now possible from eDNA in snow tracks, underlining its vast potential to complement the non-invasive genetic methods used for wildlife. To fully leverage the application of snow track eDNA, improved understanding of the ideal species- and site-specific sampling conditions, as well as laboratory methods promoting genotyping success, is needed. This will also inform efforts to retrieve and type nuclear DNA from other eDNA samples, thereby advancing eDNA-based individual and population-level studies.

From Site-Specific Sampling to Gamification: An exploration of performative engagement with the environment

This article explores strategies that allow electronic music performers to engage their audiences and environments in live acts of co-creation. We outline our existing musical practice relying on site-specific sampling and digital mobile technologies that have been tested across a range of participatory music performances. Salient challenges within this performance context are identified and several tools and techniques are proposed as solutions. We then consider how setting-based and sample-based participatory performances can be expanded through gamification strategies. After exploring how notions of playful experience can offer new insights into the nature of audience engagement, we propose several approaches for introducing gamified elements into performative music practices that can expand the scope of audience participation while preserving key aspects of using concert location recordings and musical improvisation. We conclude by discussing the implications of these approaches for the performer–audience relationship and the prospect of musical engagement with the environment before suggesting directions for future research.

Optimizing Sampling Strategies for Near-Surface Soil Carbon Inventory: One Size Doesn’t Fit All

Soils comprise the largest pool of terrestrial carbon yet have lost significant stocks due to human activity. Changes to land management in cropland and grazing systems present opportunities to sequester carbon in soils at large scales. Uncertainty in the magnitude of this potential impact is largely driven by the difficulties and costs associated with measuring near-surface (0–30 cm) soil carbon concentrations; a key component of soil carbon stock assessments. Many techniques exist to optimize sampling, yet few studies have compared these techniques at varying sample intensities. In this study, we performed ex-ante, high-intensity sampling for soil carbon concentrations at four farms in the eastern United States. We used post hoc Monte-Carlo bootstrapping to investigate the most efficient sampling approaches for soil carbon inventory: K-means stratification, Conditioned Latin Hypercube Sampling (cLHS), simple random, and regular grid. No two study sites displayed similar patterns across all sampling techniques, although cLHS and grid emerged as the most efficient sampling schemes across all sites and strata sizes. The number of strata chosen when using K-means stratification can have a significant impact on sample efficiency, and we caution future inventories from using small strata n, while avoiding even allocation of sample between strata. Our findings reinforce the need for adaptive sampling methodologies where initial site inventory can inform primary, robust inventory with site-specific sampling techniques.

Small airways obstruction and its risk factors in the Burden of Obstructive Lung Disease (BOLD) study: a multinational cross-sectional study

Small airways obstruction is a common feature of obstructive lung diseases. Research is scarce on small airways obstruction, its global prevalence, and risk factors. We aimed to estimate the prevalence of small airways obstruction, examine the associated risk factors, and compare the findings for two different spirometry parameters. The Burden of Obstructive Lung Disease study is a multinational cross-sectional study of 41 municipalities in 34 countries across all WHO regions. Adults aged 40 years or older who were not living in an institution were eligible to participate. To ensure a representative sample, participants were selected from a random sample of the population according to a predefined site-specific sampling strategy. We included participants' data in this study if they completed the core study questionnaire and had acceptable spirometry according to predefined quality criteria. We excluded participants with a contraindication for lung function testing. We defined small airways obstruction as either mean forced expiratory flow rate between 25% and 75% of the forced vital capacity (FEF25-75) less than the lower limit of normal or forced expiratory volume in 3 s to forced vital capacity ratio (FEV3/FVC ratio) less than the lower limit of normal. We estimated the prevalence of pre-bronchodilator (ie, before administration of 200 μg salbutamol) and post-bronchodilator (ie, after administration of 200 μg salbutamol) small airways obstruction for each site. To identify risk factors for small airways obstruction, we performed multivariable regression analyses within each site and pooled estimates using random-effects meta-analysis. 36 618 participants were recruited between Jan 2, 2003, and Dec 26, 2016. Data were collected from participants at recruitment. Of the recruited participants, 28 604 participants had acceptable spirometry and completed the core study questionnaire. Data were available for 26 443 participants for FEV3/FVC ratio and 25 961 participants for FEF25-75. Of the 26 443 participants included, 12 490 were men and 13 953 were women. Prevalence of pre-bronchodilator small airways obstruction ranged from 5% (34 of 624 participants) in Tartu, Estonia, to 34% (189 of 555 participants) in Mysore, India, for FEF25-75, and for FEV3/FVC ratio it ranged from 5% (31 of 684) in Riyadh, Saudi Arabia, to 31% (287 of 924) in Salzburg, Austria. Prevalence of post-bronchodilator small airways obstruction was universally lower. Risk factors significantly associated with FEV3/FVC ratio less than the lower limit of normal included increasing age, low BMI, active and passive smoking, low level of education, working in a dusty job for more than 10 years, previous tuberculosis, and family history of chronic obstructive pulmonary disease. Results were similar for FEF25-75, except for increasing age, which was associated with reduced odds of small airways obstruction. Despite the wide geographical variation, small airways obstruction is common and more prevalent than chronic airflow obstruction worldwide. Small airways obstruction shows the same risk factors as chronic airflow obstruction. However, further research is required to investigate whether small airways obstruction is also associated with respiratory symptoms and lung function decline. National Heart and Lung Institute and Wellcome Trust. For the Dutch, Estonian, French, Icelandic, Malay, Marathi, Norwegian, Portuguese, Swedish and Urdu translations of the abstract see Supplementary Materials section.

The Efficiency of Mechanized Mineral Processing Techniques to Recover Tin and Tantalum Ores. Case Study: Nyamatete Concession, Rwanda

Mining activities have resulted in a large volume of tailings containing a certain proportion of lost minerals, making them a potential reprocessing opportunity, and information on tailings and mineral reprocessing is often scarce. In this study, a conceptual framework was established and used to produce meaningful information and knowledge from the tailings of the Nyamatete mine at HABATU Mining Company Limited (an ASM in Rwanda). Tailings particles were investigated based on the observed lithology to determine their distribution over the tailing dams, and a site-specific sampling approach and procedure were established. Sieving the collected samples, particle size analysis, and chemical analysis using XRF were chosen as methods for tailings characterization. Raw materials such as SnO2, minor Ta2O5, and Nb2O5 and elements of environmental importance such as Mn, Co, and as were observed but in small quantities are largely predominant in quartz vein, have been discovered in Nyamatete tailings. The comminution and gravity separation by mechanical reprocessing facilities improved Cassiterite recovery by 43.9 % compared to the artisanal processing method. SnO2 recovery of 19.4 % and 29.9 % with grades of 63.224 % and 76.6 % were obtained in pegmatite and quartz tailings respectively. According to a scoping study, the Habatu tailings have an appropriate grade, the valuable content occurs in a recoverable grain-size range, and the total ore amount scales with the required input for the reprocessing equipment. Tailings reprocessing with mechanized reprocessing equipment is advantageous because it improves efficiency while also treating the material with previously unknown quantities of ore, thereby significantly increasing the total recovery of processed Run of Mine. Keywords: Artisanal processing; Cassiterite; Coltan; Mechanized processing; Tailings.

Smart capsule for targeted proximal colon microbiome sampling

The gastrointestinal (GI) tract, particularly the colon region, holds a highly diverse microbial community that plays an important role in the metabolism, physiology, nutrition, and immune function of the host body. Accumulating evidence has revealed that alteration in these microbial communities is the pivotal step in developing various metabolic diseases, including obesity, inflammatory bowel disease (IBD), and colorectal cancer. However, there is still a lack of clear understanding of the interrelationship between microbiota and diet as well as the effectiveness of chemoprevention strategies, including pre and probiotic agents in modifying the colonic microbiota and preventing digestive diseases. Existing methods for assessing these microbiota-diet interactions are often based on samples collected from the feces or endoscopy techniques which are incapable of providing information on spatial variations of the gut microbiota or are considered invasive procedures. To address this need, here we have developed an electronic-free smart capsule that enables site-specific sampling of the gut microbiome within the proximal colon region of the GI tract. The 3D printed device houses a superabsorbent hydrogel bonded onto a flexible polydimethylsiloxane (PDMS) disk that serves as a milieu to collect the fluid in the gut lumen and its microbiome by rapid swelling and providing the necessary mechanical actuation to close the capsule after the sampling is completed. The targeted colonic sampling is achieved by coating the sampling aperture on the capsule with a double-layer pH-sensitive enteric coating, which delays fluid in the lumen from entering the capsule until it reaches the proximal colon of the GI tract. To identify the appropriate pH-responsive double-layer coating and processing condition, a series of systematic dissolution characterizations in different pH conditions that mimicked the GI tract was conducted. The effective targeted microbial sampling performance and preservation of the smart capsule with the optimized design were validated using both realistic in vitro GI tract models with mixed bacteria cultures and in vivo with pigs as an animal model. The results from 16s rRNA and WideSeq analysis in both in vitro and in vivo studies showed that the bacterial population sampled within the retrieved capsule closely matched the bacterial population within the targeted sampling region (proximal colon). Herein, it is envisioned that such smart sampling capsule technology will provide new avenues for gastroenterological research and clinical applications, including diet-host-microbiome relationships, focused on human GI function and health. Statement of significanceThe colonic microbiota plays a major role in the etiology of numerous diseases. Extensive efforts have been conducted to monitor the gut microbiome using sequencing technologies based on samples collected from feces or mucosal biopsies that are typically obtained by colonoscopy. Despite the simplicity of fecal sampling procedures, they are incapable of preserving spatial and temporal information about the bacteria through the gastrointestinal (GI) tract. In contrast, colonoscopy is an invasive and impractical approach to frequently assess the effect of dietary and therapeutic intake on the microbiome and their impact on the health of the patient. Here, we developed a non-invasive capsule that enables targeted sampling from the ascending colon, thereby providing crucial information for disease prediction and monitoring.

Timing of Vaccine Decision-Making Among First-Time Parents.

Decreased childhood vaccination can lead to local outbreaks of vaccine-preventable disease. In a pilot study from our group, 72% of parents of newborns reported initiating their vaccine decision-making for that child prior to conception. Since a sound understanding of the timing of parental vaccine decision-making is needed to direct educational efforts, we surveyed a national cohort of first-time parents to extend our preliminary findings. From March 2019 to March 2020, first-time parents of newborns in mother-baby units of the Better Outcomes through Research for Newborns (BORN) network completed the Vaccine Preference Development Survey (VPDS). The VPDS measures intent to vaccinate, timing of vaccine decision-making, and sources of influence. Univariate and multivariate analyses explored associations between intent to vaccinate and timing of vaccine decision-making with demographic variables. Twenty-three sites provided surveys through site-specific nonrandom systemic sampling; 91% (1393/1524) of surveys were used in the analysis. Most parents planned to fully vaccinate (1191/1380, 86.3%) and started vaccine decision-making prior to conception (850/1378, 61.7%). Maternal age, race and ethnicity, relationship status, and education were all significantly associated with planning to fully vaccinate and preconception decision-making (P < .001). Preconception decision-making correlated strongly with intent to fully vaccinate (P < .001). Parents influenced by personal education, medical professionals, and family/friends were more likely to endorse preconception decision-making; those strongly influenced by internet/social media were less likely to allow all vaccines or start decision-making prior to conception. Vaccine decision-making occurs preconception for most new parents. Initiating vaccine discussions during the birth hospitalization may be too late.

Retrofitting urban land through integrative, subsoils-based planning of green stormwater infrastructure: a research framework

Abstract We present a research framework that integrates native subsoil performance and surface retrofitting into coordinated green stormwater infrastructure (GSI) planning. This framework provides communities a strategy to move beyond opportunistic GSI, which can be limited to capturing marginal amounts of stormwater, toward more impactful, coordinated GSI planning that restores the lost hydrologic functioning of the pre-development landscape. We create this framework by establishing critical performance-based relationships among four variables: (1) saturated hydraulic conductivity of native subsoils (∼upper 2 m below urban compaction and fill); (2) GSI design depth for both rain gardens and permeable pavement (in increments of 6″ from 12–30″ for planted and paved GSI); (3) loading ratio, defined as the ratio of GSI retrofit area to upstream impervious surface runoff area (from 1:2 to 1:5 for planted GSI; and 1:1 and direct infiltration for paved GSI); and (4) design storms (rainfall quantity up to 5-inches over 2 h and 24 h durations). We model the four variables using GSI models (built in the US Environmental Protection Agency’s Storm Water Management Model) and reliability analysis, a risk-assessment method adapted to characterize the reliability of GSI in response to varying stormwater runoff loading. The outcome of the modeling is a set of fragility curves and design prototypes, adjustable to catchment and sub-catchment scales, to assist municipalities in early funding and investment decisions to retrofit urbanized land through GSI. We also share two piloted applications in which we use the research framework within the Chicago-Calumet region in Illinois, USA, to conduct site-specific subsoil sampling and determinations of saturated hydraulic conductivity and to develop urban-scale GSI retrofit scenarios. Our framework is transferable to other urban regions, and particularly useful where a lack of integrating native subsoil performance into GSI design hinders decision-making, coordinated GSI planning at scale, and achieving high runoff reduction targets.

Spatially resolved analysis of Pseudomonas aeruginosa biofilm proteomes measured by laser ablation sample transfer.

Heterogeneity in the distribution of nutrients and oxygen gradients during biofilm growth gives rise to changes in phenotype. There has been long term interest in identifying spatial differences during biofilm development including clues that identify chemical heterogeneity. Laser ablation sample transfer (LAST) allows site-specific sampling combined with label free proteomics to distinguish radially and axially resolved proteomes for Pseudomonas aeruginosa biofilms. Specifically, differential protein abundances on oxic vs. anoxic regions of a biofilm were observed by combining LAST with bottom up proteomics. This study reveals a more active metabolism in the anoxic region of the biofilm with respect to the oxic region for this clinical strain of P. aeruginosa, despite this organism being considered an aerobe by nature. Protein abundance data related to cellular acclimations to chemical gradients include identification of glucose catabolizing proteins, high abundance of proteins from arginine and polyamine metabolism, and proteins that could also support virulence and environmental stress mediation in the anoxic region. Finally, the LAST methodology requires only a few mm2 of biofilm area to identify hundreds of proteins.

Hyperspectral remote sensing for detecting geotechnical problems at Ray mine

While many or most geotechnical problems at open-pit mines are related to geological structures or discontinuities, highwall movement and failure can also occur as a consequence of nonstructural geological factors. Nonstructural causes of movement are not amenable to detection by conventional geotechnical sensing techniques such as LiDAR. In this case study, we applied hyperspectral remote sensing for large-scale mapping and detection of minerals at a non-structure-related ground instability in the highwalls of the Ray mine near Tucson, Arizona. The spectral images, obtained and integrated with radar images and the geological map, show that the dominant spectrally active mineral underlying the unstable area is the swelling clay montmorillonite, whereas kaolinite and white mica are more common in more stable parts of the highwall. The montmorillonite is concentrated in an outcropping altered diabase and conglomerate that underlie more competent rocks, providing a potential lift and slip surface. This study shows that hyperspectral remote sensing can aid in geotechnical slope characterization, particularly for nonstructural causes of failure. We provide a brief overview of best practices for hyperspectral remote sensing in geotechnical applications (combining drone- and tripod-mounted sensors, integrating hyperspectral with LiDAR and radar data, and using an iteratively refined spectral library based on site-specific sampling supported by ground truth).

Considerations for toxicity experiments and risk assessments with PFAS mixtures.

Per- and polyfluoroalkyl substances (PFAS) have been around for decades and have been the subject of laboratory and field research studies for nearly as long. Although attention to PFAS has grown in recent years, many unanswered questions remain. Accordingly, the number of research projects designed to improve our understanding of PFAS toxicity, bioaccumulation, and biomagnification, and to improve our ability to predict the interactions of PFAS mixtures, is also increasing. The growing number of ongoing and future research projects focusing on these chemicals will benefit from lessons learned in previous studies. This perspectives article discusses available approaches to mixture risk assessment with specific focus on application to PFAS mixtures. We discuss ongoing research as well as lessons learned from approaches to handling mixtures of other groups of chemicals. Many of these approaches require some detailed understanding of a manageable number of representative chemicals, yet only limited toxicological data are available for most PFAS. With the limited amount of published data currently available, the need for single-chemical and binary-mixture studies persists. Based on our previous work with single-chemical exposures for understudied PFAS, we explored some of the challenges of trying to design and interpret an aquatic concentration-response experiment for a binary mixture of two commonly detected PFAS: perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonic acid (PFHxS). Based on our findings, we propose that addressing risk from PFAS mixtures will likely require combinations of approaches incorporating findings from traditional whole-organism toxicity studies and novel methods relying on in vitro assays, read-across, or quantitative structure activity relationships. Complicating a limited understanding of PFAS mixture toxicity is that relative concentrations of PFAS mixtures vary across sites and time, even at one site. Thus, reliance on empirical data, such as site-specific toxicity sampling or community structure studies, may be needed to fully understand potential impacts of mixtures. Integr Environ Assess Manag 2021;17:697-704. © 2021 SETAC.

A Systematic Framework for Collecting Site-Specific Sampling and Survey Data to Support Analyses of Health Impacts from Land-Based Pollution in Low- and Middle-Income Countries.

The rise of small-scale and localized economic activities in low- and middle-income countries (LMICs) has led to increased exposures to contaminants associated with these processes and the potential for resulting adverse health effects in exposed communities. Risk assessment is the process of building models to predict the probability of adverse outcomes based on concentration-response functions and exposure scenarios for individual contaminants, while epidemiology uses statistical methods to explore associations between potential exposures and observed health outcomes. Neither approach by itself is practical or sufficient for evaluating the magnitude of exposures and health impacts associated with land-based pollution in LMICs. Here we propose a more pragmatic framework for designing representative studies, including uniform sampling guidelines and household surveys, that draws from both methodologies to better support community health impact analyses associated with land-based pollution sources in LMICs. Our primary goal is to explicitly link environmental contamination from land-based pollution associated with specific localized economic activities to community exposures and health outcomes at the household level. The proposed framework was applied to the following three types of industries that are now widespread in many LMICs: artisanal scale gold mining (ASGM), used lead-acid battery recycling (ULAB), and small tanning facilities. For each activity, we develop a generalized conceptual site model (CSM) that describes qualitative linkages from chemical releases or discharges, environmental fate and transport mechanisms, exposure pathways and routes, populations at risk, and health outcomes. This upfront information, which is often overlooked, is essential for delineating the contaminant zone of influence in a community and identifying relevant households for study. We also recommend cost-effective methods for use in LMICs related to environmental sampling, biological monitoring, survey questionnaires, and health outcome measurements at contaminated and unexposed reference sites. Future study designs based on this framework will facilitate consistent, comparable, and standardized community exposure, risk, and health impact assessments for land-based pollution in LMICs. The results of these studies can also support economic burden analyses and risk management decision-making around site cleanup, risk mitigation, and public health education.

The fate of plastic litter within estuarine compartments: An overview of current knowledge for the transboundary issue to guide future assessments.

Plastics can enter biogeochemical cycles and thus be found in most ecosystems. Most studies emphasize plastic pollution in oceanic ecosystems even though rivers and estuaries are acknowledged as the main sources of plastics to the oceans. This review detected few studies approaching the transboundary issue, as well as patterns of estuarine gradients in predicting plastic distribution and accumulation in water, sediments, and organisms. Quantities of plastics in estuaries reach up to 45,500 items m-3 in water, 567,000 items m-3 in sediment, and 131 items per individual in the biota. The role of rivers and estuaries in the transport of plastics to the ocean is far from fully understood due to small sample sizes, short-term approaches, sampling techniques that underestimate small plastics, and the use of site-specific sampling rather than covering environmental gradients. Microfibres are the most commonly found plastic type in all environmental matrices but efforts to re-calculate pathways using novel sampling techniques and estimates are incipient. Microplastic availability to estuarine organisms and rising/sinking is determined by polymer characteristics and spatio-temporal fluctuations in physicochemical, biological, and mineralogical factors. Key processes governing plastic contamination along estuarine trophic webs remain unclear, as most studies used "species" as an ecological unit rather than trophic/functional guilds and ontogenetic shifts in feeding behaviour to understand communities and intraspecific relationships, respectively. Efforts to understand contamination at the tissue level and the contribution of biofouling organisms as vectors of contaminants onto plastic surfaces are increasing. In conclusion, rivers and estuaries still require attention with regards to accurate sampling and conclusions. Multivariate analysis and robust models are necessary to predict the fate of micro- and macroplastics in estuarine environments; and the inclusion of the socio-economic aspects in modelling techniques seems to be relevant regarding management approaches.

Systematic characterization of historical tailings for possible remediation and recovery of critical metals and minerals – The Yxsjöberg case

As the need to address environmental concerns in mining and the demand for critical metals and minerals increase, historical tailings are among the mining waste repositories being sought after. However, there is only limited information available about such repositories, and hence there is a need to fill these knowledge gaps. In this paper, a conceptual framework is proposed for how relevant information about historical tailings can be generated and structured in a systematic manner. The case of the closed Yxsjöberg mine in Sweden is used to demonstrate how this framework is being used. A site-specific sampling strategy and technique was identified, and based on the observed lithology, tailings particles were studied to understand their distribution across the repository. Using Mineral Liberation Analysis (MLA), the modal mineralogy, mineral associations, and mineral liberation by particle size of the tailings were determined. The Smaltjärnen tailings repository of Yxsjöberg has potential for critical metals and minerals, including tungsten (W) and fluorite (CaF2) but also contains minerals of environmental concern as pyrrhotite and pyrite. It has on average 0.15% WO3 concentration in the sampled locations, indicating approximately 3300 tons of WO3 in the repository. Scheelite mineral grains are mostly (>50 wt%) locked in tailings particles that have a number of mineral grains (binary, ternary or even more complex) in the dominating particle size fraction −600 to +149 μm. Mineral locking is mostly with calcium-bearing minerals ilvaite, fluorite and garnet-gross-andradite. Pyrrhotite has been the most reactive acid-generating mineral, and hence is more depleted than pyrite in the weathered locations. The heterogeneity of tailings across the repository suggests a possible existence of geometallurgical domains that require further assessment to evaluate their metallurgical performance. The obtained information and knowledge about these tailings will hereinafter be used to develop sustainable processes for remediation and recovery of the critical metals and minerals.

Combined Focused Ion Beam-Ultramicrotomy Method for TEM Specimen Preparation of Porous Fine-Grained Materials.

A new transmission electron microscopy (TEM) specimen preparation method that utilizes a combination of focused ion beam (FIB) methods and ultramicrotomy is demonstrated. This combined method retains the benefit of site-specific sampling by FIB but eliminates ion beam-induced damage except at specimen edges and allows recovery of many consecutive sections. It is best applied to porous and/or fine-grained materials that are amenable to ultramicrotomy but are located in bulk samples that are not. The method is ideal for unique samples from which every specimen is precious, and we demonstrate its utility on fine-grained material from the one-of-a-kind Paris meteorite. Compared with a specimen prepared by conventional FIB methods, the final sections are uniformly thin and free from re-deposition and curtaining artifacts common in FIB specimens prepared from porous, heterogeneous samples.

Spatial distribution of mercury and other potentially toxic elements using epiphytic lichens in Nova Scotia.

The use of naturally occurring epiphytic lichens can be an effective tool for regional monitoring of mercury (Hg) and other potentially toxic elements (PTEs). Nova Scotia, Canada is a hotspot for mercury and other trace metal accumulation in ecosystems; partially attributed to long-range transport of air pollution. The relative contribution of local and international sources of Hg to local air in Nova Scotia is unknown. This study assessed the potential of epiphytic lichens (Usnea spp.) as passive samplers for PTE air pollution in Nova Scotia. Lichens (n = 190) collected across mainland Nova Scotia were analyzed for PTEs. Results indicate that there are 3 distinct clusters of PTEs which suggest patterns and sources for each elemental cluster. Hg was correlated with longitude and prevailing wind direction, and Hg was not significantly different in site-specific hotspot sampling nor year of sampling. Our data support the hypothesis that Hg in lichens is from historical and ongoing long-range transport and diffuse emission patterns rather than localized pollution sources. PTE concentrations were shown to have median values that are similar to other remote regions (such as the Antarctic) however the maximum values were observed to be substantially higher for some elements (e.g. lead, cadmium). This research supports the use of lichens as biomonitors and provides a baseline for future monitoring efforts to identify changes in PTE distribution in Nova Scotia with ongoing industrial activity and a changing climate.

Current-use pesticides in New Zealand streams: Comparing results from grab samples and three types of passive samplers

New Zealand uses more than a ton of pesticides each year; many of these are mobile, relatively persistent, and can make their way into waterways. While considerable effort goes into monitoring nutrients in agricultural streams and programs exist to monitor pesticides in groundwater, very little is known about pesticide detection frequencies, concentrations, or their potential impacts in New Zealand streams. We used the ‘Polar Organic Chemical Integrative Sampler’ (POCIS) approach and grab water sampling to survey pesticide concentrations in 36 agricultural streams in Waikato, Canterbury, Otago and Southland during a period of stable stream flows in Austral summer 2017/18. We employed a new approach for calculating site-specific POCIS sampling rates. We also tested two novel passive samplers designed to reduce the effects of hydrodynamic conditions on sampling rates: the ‘Organic-Diffusive Gradients in Thin Films’ (o-DGT) aquatic passive sampler and microporous polyethylene tubes (MPTs) filled with Strata-X sorbent. Multiple pesticides were found at most sites; two or more were detected at 78% of sites, three or more at 69% of sites, and four or more at 39% of sites. Chlorpyrifos concentrations were the highest, with a maximum concentration of 180 ng/L. Concentrations of the other pesticides were generally below 20 ng/L. Mean concentrations of individual pesticides were not correlated with in-stream nutrient concentrations. The majority of pesticides were detected most frequently in POCIS, presumably due to its higher sampling rate and the relatively low concentrations of these pesticides. In contrast, chlorpyrifos was most frequently detected in grab samples. Chlorpyrifos concentrations at two sites were above the 21-day chronic ‘No Observable Effect Concentration’ (NOEC) values for fish and another two sites had concentrations greater than 50% of the NOEC. Otherwise, concentrations were well-below NOEC values, but close to the New Zealand Environmental Exposure Limits in several cases.

Site-Specific Cytosol Sampling from a Single Cell in an Intact Tumor Spheroid Using an Electrochemical Syringe.

A multicellular tumor aggregate, known as a spheroid, is an indispensable tool to study cancer biology. Owing to its three-dimensional organization, a spheroid exhibits an inherent gradient of nutrients, oxygen, and metabolites within itself. The spheroid provides culture conditions that resemble the microenvironment of certain cancer cells and causes these cells to acquire characteristics relevant to tumors in our body. However, site-specific gene expression analysis in an intact spheroid with single-cell resolution has not been explored. Recently, some types of electrochemical syringes were developed to extract cellular materials from living single cells for transcriptomic analysis. Here, we investigated whether an electrochemical syringe could be used to evaluate site-specific gene expression in a spheroid. A small amount of cytosol (roughly 540-1480 fL, less than the volume of a single cell) was successfully collected from the first, second, and third layers of the spheroid using an electrochemical syringe without causing damage to the spheroid architecture. We found that the CCNB1 and CCNA2 expression levels were different between the surface and the average of the entire spheroid, indicating that there are heterogeneous cellular functions across different regions of the spheroid. This method provides opportunities to improve our understanding of spatial gene expression of single cells in a three-dimensional environment.

Abstract No. 474 A Pilot study of the feasibility of ultrasound-PET/CT fusion–guided supraclavicular brown adipose tissue biopsy

To determine the feasibility of ultrasound-PET/CT fusion imaging guidance for supra-clavicular adipose tissue biopsies This IRB-approved prospective study included seven healthy volunteers (5F/2M) who had a prior 18F-FDG PET/CT showing metabolically active BAT. Manual registration of the ipsilateral sterno-clavicular joint was performed using an electromagnetically tracked 15-7io probe. A 2D ultrasound sweep of the ipsilateral clavicle was then obtained after manual alignment of the electromagnetic tracking space to the patient. A 3D ultrasound volume was reconstructed and then registered to the CT portion of the PET/CT image. Manual correction of image fusion was carried out on an as-needed basis. Ultrasound/CT/PET fusion was displayed in real-time for biopsy guidance. Biopsies were performed with 14-16G Temno needles under direct ultrasound visualization in the fused image. BAT was confirmed via 1) the presence of mRNA for uncoupling protein 1 (UCP1), the thermogenic protein specific to brown adipocytes, and 2) comparison of levels obtained from adjacent subcutaneous white adipose tissue (WAT) obtained from each subject. From the seven subjects enrolled, deep supraclavicular brown fat was acquired from 6/7 and superficial white fat from 7/7. The deep biopsies had 40X higher levels of UCP1 (P<0.001), consistent with BAT, validating the accuracy of the fused imaging guidance. Complications included self-limited site erythema (1/7), pressure (1/7), and paresthesias (1/7). Ultrasound-PET/CT fusion is a feasible approach for site-specific sampling human supraclavicular BAT and WAT. This novel method should enable a new, wide range of studies of human BAT physiology.