bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using remote sensing indicators to investigate the association of landings with fronts: Application to the Alboran Sea (western Mediterranean Sea)
Authors: Brigolin D. , Girardi P. , Miller P. I. , Xu W. , Nachite D. , Zucchetta M. , Pranovi F. 
Published: March 2018

AbstractThis study examined links between the variability of coastal front features and composition of fishery landings. Satellite‐derived sea surface temperature data allowed the detection of thermal fronts and calculation of front metrics that account for gradient, persistency, and vicinity. Landings data were clustered by functional group (according to habitat use, size, morphology), and trophic level (TL). Three independent time series analyses, based on two different classes of statistical methodologies, were carried out: (i) correlation analysis performed on species aggregated by functional groups, and (ii) compositional analysis performed on the top five species landed and on species aggregated by trophic level. Analyses were carried out for the Moroccan coast of the Alboran Sea (western Mediterranean Sea). Results of the proposed type of application were discussed with respect to their potential for improving scientific knowledge and management of fisheries in data‐poor areas. Pelagic landings were associated with front indicators in two‐thirds of tested cases. The results demonstrated a markedly different association between landings and front features in the Nador fishing zone, relative to M'diq and Al Hoceima. Improved performance of the front gradient and persistence indicator was detected, with respect to the front gradient only for flatfish and demersal landings. Compositional data regression outlined a different role for Sardina pilchardus and Trachurus trachurus in the Al Hoceima and M'diq landings, and in the latter case the dominance of these two species in the landings seemed to respond to the front density indicator. A decreasing trend in TL > 3.5 landings was detected with increasing front distance.
Climate change likely to reduce orchid bee abundance even in climatic suitable sites
Authors: Faleiro Frederico Valtuille , Nemésio André , Loyola Rafael 
Published: March 2018

AbstractStudies have tested whether model predictions based on species’ occurrence can predict the spatial pattern of population abundance. The relationship between predicted environmental suitability and population abundance varies in shape, strength and predictive power. However, little attention has been paid to the congruence in predictions of different models fed with occurrence or abundance data, in particular when comparing metrics of climate change impact. Here, we used the ecological niche modeling fit with presence–absence and abundance data of orchid bees to predict the effect of climate change on species and assembly level distribution patterns. In addition, we assessed whether predictions of presence–absence models can be used as a proxy to abundance patterns. We obtained georeferenced abundance data of orchid bees (Hymenoptera: Apidae: Euglossina) in the Brazilian Atlantic Forest. Sampling method consisted in attracting male orchid bees to baits of at least five different aromatic compounds and collecting the individuals with entomological nets or bait traps. We limited abundance data to those obtained by similar standard sampling protocol to avoid bias in abundance estimation. We used boosted regression trees to model ecological niches and project them into six climate models and two Representative Concentration Pathways. We found that models based on species occurrences worked as a proxy for changes in population abundance when the output of the models were continuous; results were very different when outputs were discretized to binary predictions. We found an overall trend of diminishing abundance in the future, but a clear retention of climatically suitable sites too. Furthermore, geographic distance to gained climatic suitable areas can be very short, although it embraces great variation. Changes in species richness and turnover would be concentrated in western and southern Atlantic Forest. Our findings offer support to the ongoing debate of suitability–abundance models and can be used to support spatial conservation prioritization schemes and species triage in Atlantic Forest.
A comparison of milk yields and methane production from three contrasting high‐yielding dairy cattle feeding regimes: Cut‐and‐carry, partial grazing and total mixed ration
Authors: Cameron L. , Chagunda M. G. G. , Roberts D. J. , Lee M. A. 
Published: March 2018

AbstractThere have been reductions in grazing cattle and corresponding increases in mixed diets across many regions. Mixed diets consist of silage, grains, legumes and other herbaceous plants (termed total mixed ration, TMR). TMR has been associated with increased milk yields but has also been linked to increased enteric methane production. We measured milk yields and methane production from high‐yielding Holstein‐Friesian cattle after substituting 29%–36% of a TMR diet with grass. Two feeding treatments were compared with a diet of TMR: grass grazed at pasture and grass cut in the field and delivered to housed cattle (termed cut‐and‐carry). Each feeding treatment was fed to 15 cattle, and the experiment was conducted in South‐west Scotland. Using a laser methane detector, we measured a twofold and fourfold decline in enteric methane production for the cut‐and‐carry and grazing groups, respectively, when the animals consumed grass. TMR was consumed by both grass‐fed groups overnight, so daily values were adjusted to include elevated methane production during this period. This revealed that methane production for the cut‐and‐carry and grazing groups was 17% and 39% lower than for the TMR‐fed group respectively. Milk yields were maintained for all three groups, and the efficiency of milk production per unit of methane was substantially greater for the two grass‐fed groups. A shift away from exclusively feeding TMR by adding fresh grass to the diets of cattle could contribute to meeting emissions targets and could also represent an economically sustainable climate change mitigation strategy.
Natural history of gastric cancer from a retrospective review of endoscopic images of older patients with interval gastric cancer
Authors: Iida Tomoya , Yamashita Kentaro , Ohwada Sae , Ohkubo Yosuke , Hirano Takehiro , Miyake Takakazu , Onodera Kei , Kubo Toshiyuki , Yamano Hiroo , Nakase Hiroshi 
Published: March 2018

AimInterval gastric cancers (IGC) are defined as those diagnosed after negative results of endoscopy carried out within the past 10 years. We aimed to investigate the characteristics of IGC and the natural history of gastric cancer (GC) from a retrospective view of endoscopic images of older patients with IGC.MethodsWe retrospectively reviewed endoscopic images of 240 patients with GC who were aged >60 years. We compared past endoscopic images with newer ones, in which GC was diagnosed. IGC were classified into two categories: missed cancers and new cancers.ResultsOf the 240 patients with GC, 32 had past endoscopic images that qualified for a precise review. A total of 14 cases involved new cancers, whereas 18 involved missed cancers. Most of the IGC were stage I for at least 2 years; however, a small subset was unresectable at >2 years after a negative endoscopy. Furthermore, the rate of endoscopic treatment was significantly higher for IGC compared with that for non‐IGC.ConclusionsIn people aged >60 years, most IGC remain in an early stage for at least 2 years; however, at >2 years after a negative endoscopy, some are unresectable. These results suggest that most early‐stage GC will not develop into advanced cancers within 2 years; thus, a 2‐year interval might be within the permissible range for patients with negative endoscopy results for any lesions. Geriatr Gerontol Int 2018; 18: 997–1002
Effects of Glacial Sediment Type and Land Use on Nitrate Patterns in Groundwater
Authors: Best Anna , Arnaud Emmanuelle , Parker Beth , Aravena Ramon , Dunfield Kari 
Published: March 2018

AbstractGrowing population centers such as those in southern Ontario rely on fractured bedrock aquifers for drinking water. A threat to these aquifers is posed by surficial nonpoint‐source pollution infiltrating with rainwater and moving through the overlying Quaternary glacial deposits. Investigation of local unconsolidated sediments, and the factors affecting contaminant transport through these, is needed to assess risks to the quality of underlying groundwater resources. In this study, sites with a variety of agricultural land management practices and glacial geologic settings were investigated by employing high‐resolution data collection methods. Geologic data from continuous sediment cores were combined with depth‐discrete hydrogeologic and geochemical parameter measurements using high‐resolution multilevel monitoring wells. Within a relatively small geographic area with three distinct glacially derived sediment types, the three sites exhibited greatly disparate vulnerability to nitrate contamination. The geologic setting, including surface topography and architecture and heterogeneity of sediment types at depth, influenced groundwater flow paths and water geochemistry, and subsequently, nitrate distribution. Although management practices influence the quantity of pollutants leaching to groundwater resources, the physical and chemical properties of the subsurface related to the geologic setting ultimately determine the persistence or attenuation of nitrate, and therefore become important to characterize when evaluating best nutrient and waste management practices.
Challenges and a Strategy for Agricultural BMP Monitoring and Remediation of Nitrate Contamination in Unconsolidated Aquifers
Authors: Rudolph D.L. , Devlin J.F. , Bekeris L. 
Published: March 2018

AbstractNitrate in groundwater and surface water is among the most common contamination problems in the world. Efforts to reduce the loss of excess nutrients at the regional scale currently focus on Best Management Practices (BMPs) designed to facilitate the optimal use of fertilizers, adjusted for specific site conditions. Performance monitoring of regional BMPs has proven to be problematic owing to the large areal scales, the inherent heterogeneity of nutrient mobility on landscapes and in the subsurface, and the extended time lag between implementation and overall improvements in groundwater quality. In order to shorten the time for useful assessments of progress and for the beneficial results to be realized, a strategy is proposed here with specific application to unconsolidated granular aquifers. First, a novel approach for quantifying BMP performance in the short term is demonstrated involving the monitoring of transient nitrate storage in the unsaturated zone. Secondly, a temporary remediation method based on in situ denitrification is implemented for reducing nitrate levels in public supply wells in the interim period until the full influence of the regional nutrient management BMPs is realized. The remediation approach incorporates a passive component that necessitates enhanced site characterization methods including high definition assessments of aquifer properties and groundwater velocity. The preliminary findings from a series of field investigations conducted between 2004 and 2011 at a site in southern Ontario indicate that this combined two‐step strategy may be capable of providing short‐term quantifiable evidence of BMP performance and also of attenuating nitrate to desirable levels during the time lag period between implementation of the BMPs and the arrival of their desired beneficial effects on the quality of public well water supplies. This may avoid the need to construct permanent above‐ground water treatment facilities that could eventually become redundant.
Review of Abiotic Degradation of Chlorinated Solvents by Reactive Iron Minerals in Aquifers
Authors: He Y. T. , Wilson J. T. , Su C. , Wilkin R. T. 
Published: March 2018

AbstractAbiotic degradation of chlorinated solvents by reactive iron minerals such as iron sulfides, magnetite, green rust, and other Fe(II)‐containing minerals has been observed in both laboratory and field studies. These reactive iron minerals form under iron‐ and sulfate‐reducing conditions which are commonly found in permeable reactive barriers (PRBs), enhanced reductive dechlorination (ERD) treatment locations, landfills, and aquifers that are chemically reducing. The objective of this review is to synthesize current understanding of abiotic degradation of chlorinated solvents by reactive iron minerals, with special focus on how abiotic processes relate to groundwater remediation. Degradation of chlorinated solvents by reactive minerals can proceed through reductive elimination, hydrogenolysis, dehydrohalogenation, and hydrolysis reactions. Degradation products of abiotic reactions depend on degradation pathways and parent compounds. Some degradation products (e.g., acetylene) have the potential to serve as a signature product for demonstrating abiotic reactions. Laboratory and field studies show that various minerals have a range of reactivity toward chlorinated solvents. A general trend of mineral reactivity for degradation of chlorinated solvents can be approximated as follows: disordered FeS > FeS > Fe(0) > FeS2 > sorbed Fe2+ > green rust = magnetite > biotite = vermiculite. Reaction kinetics are also influenced by factors such as pH, natural organic matter (NOM), coexisting metal ions, and sulfide concentration in the system. In practice, abiotic reactions can be engineered to stimulate reactive mineral formation for groundwater remediation. Under appropriate site geochemical conditions, abiotic reactions can occur naturally, and can be incorporated into remedial strategies such as monitored natural attenuation.
A Simple and Affordable System for Installing Shallow Drive Point Piezometers
Authors: Burk Lawrence , Cook Peter G. 
Published: March 2018

AbstractThis paper describes a drive point system for installing small‐diameter (15 to 25 mm ID) piezometers to depths of several metres in unconsolidated sediments. The system fills the gap between (1) heavy duty drive point systems powered by drilling rig hydraulics or air hammers that are capable of installing large diameter drive points to depths of many tens of metres and (2) manually driven systems that typically install 10 mm ID or smaller tubing to depths of <2 m. Unlike many existing systems, which install piezometers inside an outer casing that is later removed, our system protects the piezometer screen inside the casing and extends it only once the casing is driven to the desired depth. This avoids clogging of the screen during installation and the risk of creating an annulus around the piezometer, which can provide a preferential pathway for water movement. The piezometer has a larger diameter than most manually driven systems, and thus has a higher yield; it also permits use of most commercially available pressure transducers and electrical conductivity sensors. The piezometers have been successfully installed to depths of up to 6 m using an electric hammer. The system overcomes some issues associated with existing systems and provides the advantages of affordability, rapid installation, mechanical assistance and manual portability.
Biofilm Detection in a Model Well‐Bore Environment Using Low‐FieldNMR
Authors: Kirkland Catherine M. , Hiebert Randy , Phillips Adrienne , Grunewald Elliot , Walsh David O. , Seymour Joseph D. , Codd Sarah L. 
Published: March 2018

AbstractThis research addresses the challenges of the lack of non‐invasive methods and poor spatiotemporal resolution associated with monitoring biogeochemical activity central to bioremediation of subsurface contaminants. Remediation efforts often include growth of biofilm to contain or degrade chemical contaminants, such as nitrates, hydrocarbons, heavy metals, and some chlorinated solvents. Previous research indicates that nuclear magnetic resonance (NMR) is sensitive to the biogeochemical processes of biofilm accumulation. The current research focuses on developing methods to use low‐costNMRtechnology to support in situ monitoring of biofilm growth and geochemical remediation processes in the subsurface. Biofilm was grown in a lab‐scale radial flow bioreactor designed to model the near wellbore subsurface environment. The Vista Clara JavelinNMRlogging device, a slim down‐the‐borehole probe, collectedNMRmeasurements over the course of eight days while biofilm was cultivated in the sand‐packed reactor. MeasuredNMRmean logT2relaxation times decreased from approximately 710 to 389 ms, indicating that the pore environment and bulk fluid properties were changing due to biofilm growth. Destructive sampling employing drop plate microbial population analysis and scanning electron and stereoscopic microscopy confirmed biofilm formation. Our findings demonstrate that theNMRlogging tool can detect small to moderate changes inT2distribution associated with environmentally relevant quantities of biofilm in quartz sand.
Evaluating the Use of In‐Well Heat Tracer Tests to Measure Borehole Flow Rates
Authors: Sellwood Stephen M. , Hart David J. , Bahr Jean M. 
Published: March 2018

AbstractRecent research has demonstrated the use of in‐well heat tracer tests monitored by a fiber optic distributed temperature sensing (DTS) system to characterize borehole flow conditions in open bedrock boreholes. However, the accuracy of borehole flow rates determined from in‐well heat tracer tests has not been evaluated. The purpose of the research presented here is to determine whether borehole flow rates obtained using DTS‐monitored in‐well heat tracer tests are reasonable, and to evaluate the range of flow rates measureable with this method. To accomplish this, borehole flow rates measured using in‐well heat tracer tests are compared to borehole flow rates measured in the same boreholes using an impeller or heat pulse flowmeter. A comparison of flow rates measured using in‐well heat tracer tests to flow rates measured with an impeller flowmeter under the same conditions showed good agreement. A comparison of in‐well heat tracer test flow rate measurements to previously‐collected heat pulse flowmeter measurements indicates that the heat tracer test results produced borehole flow rates and flow profiles similar to those measured with the heat pulse flowmeter. The results of this study indicate that borehole flow rates determined from DTS‐monitored in‐well heat tracer tests are reasonable estimates of actual borehole flow rates. In addition, the range of borehole flow rates measurable by in‐well heat tracer tests spans from less than 10−1 m/min to approximately 101 m/min, overlapping the ranges typically measurable with an impeller flowmeter or a heat pulse flowmeter, making in‐well heat tracer testing a versatile borehole flow logging tool.
Electrical Resistance Heating of Clay Layers in Water‐Saturated Sand
Authors: Martin Eric J. , Mumford Kevin G. , Kueper Bernard H. 
Published: March 2018

AbstractElectrical resistance heating (ERH) experiments were performed in a two‐dimensional water‐saturated porous medium comprising an electrically conductive, low‐permeability clay lens embedded within a less electrically conductive, higher permeability silica sand. These were compared to experiments performed in homogeneous silica sand. All experiments were performed in the absence of a non‐aqueous phase liquid (NAPL) or dissolved volatile organic compound (VOC). Temperature monitoring showed preferential heating in the clay lens and higher overall heating rates throughout the test cell compared to the homogeneous case. Gas production was localized around the sand–clay interface due to high temperature and low capillary displacement pressure. Above the clay lens, unexpected temperature plateaus were observed, similar to those observed in previous experiments during NAPL–water co‐boiling. A conceptual model based on the consumption of thermal energy as latent heat of vaporization in the highly localized heating and gas production region adjacent to the clay lens is proposed to explain the temperature plateaus. Supporting data is drawn from images of the gas phase and electric current measurements. These results show that the use of co‐boiling plateaus as an indicator of NAPL–water co‐boiling could be misleading during applications of ERH at sites containing electrically conductive, low‐permeability clay lenses embedded within less electrically conductive, higher‐permeability sands.
Evaluation of Long‐Term Performance and Sustained Treatment at Enhanced Anaerobic Bioremediation Sites
Authors: McGuire Travis M. , Adamson David. T. , Burcham Michael S. , Bedient Philip B. , Newell Charles J. 
Published: March 2018

AbstractThis study evaluated the long‐term performance of enhanced anaerobic bioremediation (EAB) at chlorinated solvent sites to determine if sustained treatment processes were helping to prevent concentration rebound. A database of groundwater concentration versus time records was compiled for 34 sites, with at least 3 years of posttreatment monitoring data (median = 4.7 years, range = 3.0 to 11.7 years). Long‐term performance was evaluated based on order‐of‐magnitude (OoM) changes in parent compound concentrations during various monitoring periods. Results indicate that, relative to the pretreatment concentration, a median concentration reduction for all 34 sites of 1.0 OoM (90% reduction) was achieved by the end of the posttreatment monitoring period. No rebound was observed at 65% of the sites between the first year of posttreatment monitoring and the final year. During this posttreatment period, Mann‐Kendall trend analysis indicated that the concentration was stable or decreasing at 89% of the sites where a trend could be established (n = 27; 33% decreasing, 56% stable, 11% increasing). Statistical analysis indicates there is no evidence that the distribution of median concentration reductions after the first year of posttreatment monitoring was different than the distribution of median reductions 2 to 11 years later at the end of the monitoring period (p = 0.67). Similarly, statistical analysis indicates that there is no evidence that the distribution of median reductions for a larger set of sites (n = 84) with less than 3 years of posttreatment monitoring data (1.1 OoM; 92% reduction) was different than the distribution of median OoM reductions for the 34‐site dataset with longer monitoring periods (p = 0.80). This suggests that, at a typical site, a 3‐year monitoring period should be sufficient for evaluating performance. The results of this study indicate that, in the long term, after the end of active treatment, sustained treatment processes contribute to relatively modest concentration reductions but do mitigate rebound at the majority of EAB sites.