ALBERT

Description: A series of direct simple shear (DSS) tests were carried out on a non-plastic sandy silt lead-zinc-silver tailings to develop a relationship between undrained shearing behaviour and density, where in situ testing had identified contractive behaviour. The critical state line was also obtained through triaxial compression tests to enable the DSS tests to be viewed in a critical state framework and allow comparison with in situ testing. It was found that the gravimetric water content (GWC) used to tamp the specimens had a significant effect on the resulting undrained strengths when attempting to achieve dense states - with higher GWC giving lower strength at a given density than a lower GWC. Intact and slurry deposited (SD) samples were also tested to access denser states without inducing tamping-related stresses. These showed a more consistent trend with the loose-tamped specimens, and with other data from the literature. Plausible explanations as to the causes of the increased strength of dense-tamped samples were obtained through estimating potential preconsolidation stresses and “locked in” horizontal stresses that may occur from dense tamping. The importance of these observations on the development of density - strength profiles in engineering practice was outlined.

Description: Accurate prediction of soil deformations is important in unloading as well as loading. Historically, however, the loading scenario has been the most common and thus the most extensively studied phenomenon, leaving unloading less well described. Overconsolidated high plasticity clays are particularly challenging in this regard due to their complex deformation behaviour that has previously shown two conceptually different unloading behaviours. Based on a series of incremental loading and constant rate of strain compression and swelling tests on folded Røsnæs Clay, these unloading behaviours are unified in a framework as different swell modes, and an additional swell mode is identified. These different modes represent a variation in swell inhibiting structure, seemingly unrelated to the structure in compression. The use of constant rate of strain tests greatly enhanced the detailed description of stiffness development in each mode, which may be characterised by up to three swell phases. The parameters governing the occurrence of the swell modes are identified along with the variables that define the transition between the swell phases and their detailed development.

Description: We quantified benthic diatom diversity in streams in the Miellajokka catchment, about 200 km north of the Arctic circle in Sweden. Beta diversity among sites was related to local-scale environmental heterogeneity (occurring on the order of 1 km or less), and its magnitude was equal (Sørensen Index = 0.62) to levels previously reported for rivers on regional environmental gradients across 100’s of kilometers of Arctic Fennoscandia. Species turnover was the dominant (77%) component of beta diversity in the Miellajokka catchment. Small, stress-tolerant taxa dominated the assemblages, and there were no clear patterns of functional class among sites. Site ordinates from non-metric dimensional scaling were most strongly correlated with flood frequency (r = 0.83) and water temperature (r = 0.89), which was higher in harsh tundra sites than below treeline. Additionally, site ordinates were correlated (r = 0.83) with ecosystem-scale gross primary production – indicative of a link between diatom diversity and ecosystem function. Our results advance understanding of patterns diatom diversity in Arctic streams by quantifying local-scale variation that is understudied in this region, and by identifying the consequences of this local-scale diversity for an ecosystem-scale process.

Description: Above average warming in the Arctic is leading to increasing permafrost temperatures and a reduction in sea ice cover, which are expected to contribute to increasing rates of Arctic coastal erosion and sediment release. We studied a 1.5 km stretch of coastline off Richard’s Island, Northwest Territories, Canada, consisting of multiple retrogressive thaw slumps (RTSs) with varying degrees of activity over a one-year period. Multi-temporal 2D and 3D geomorphic analysis was based on unmanned aerial vehicle-Structure-from-Motion (UAV-SfM) data sets collected in 2018 and 2019. Over the observation period, −3.9 m and −1.1 m of planimetric cliff edge and toe retreat occurred, respectively, and corresponded to an average volumetric change of 8.1 m3 m−1. The accuracy of UAV-SfM-derived digital elevation models was tested using 12 data collection and processing scenarios, testing the influence of off-nadir camera angle, flight pattern, and georeferencing strategy. We found that oblique imaging and georeferencing strategy had a large influence on vertical accuracy and variability across the study site and has implications for studying volumetric changes in RTSs. This study furthers the geomorphological understanding of RTS processes by highlighting the complex relationship between planimetric and volumetric change along rapidly retreating Arctic coasts, and demonstrates advancements in measurement practices for UAV-SfM data sets.

Description: Understanding the runout of slope failures is important for hazard identification, risk assessments, and disaster prevention. This study evaluates the accuracy of three runout software packages, DAN3D, Anura3D, and FLO-2D, for modeling the runout of the 2014 Oso Landslide and investigates the viability of predicting the runout of other landslides and slope failures under similar conditions. This study uses the geotechnical conditions and failure mechanism reported by Stark et al. (2017) to conduct the Oso Landslide runout analyses and assess the accuracy/applicability of the runout models using field observations. These analyses show the importance of: (1) using a digital terrain model in the runout analysis, (2) modeling field representative shear strength properties and failure mechanisms, and (3) predicting runout distance, splash height, and duration for risk assessments and to improve public safety for this and other slopes.

Description: A two-year field study was conducted on a coarse textured soil in Manitoba, Canada, to investigate the effects of liquid hog manure (LHM) and chemical fertilizer application on barley (2005) and red spring wheat (2006) yields, crop nutrient uptake and nitrogen (N) and phosphorus (P) movement to the environment. The treatments were LHM applied at two rates as 22000 L ha-1 (2500 gal ac-1, abbreviated as M2500) and 43000 L ha-1 (5000 gal ac-1, abbreviated as M5000) and two rates of chemical fertilizer to match total N and P in LHM treatments, F2500 and F5000, along with an unamended control. The M5000 and M2500 treatments showed similar grain yield and N and P uptake. However, M5000 and M2500 significantly increased grain yield by 67% and 78%, respectively, compared to the control in 2005. In 2006, wheat grain yields from M2500 and M5000 were 71% and 86% greater than the control. In 2005, leachate NO3-N concentrations and leaching loads were higher with chemical fertilizers than M2500. In 2005, the apparent recovery of applied N as leachate was 35% and 23% in F5000 and F2500 treatments, whereas it was 6% and 7% of applied N in M5000 and M2500 plots, respectively. However, the application of M5000 resulted in P accumulation near the surface and may increase the potential risk of P loss with runoff. Our results show that applying LHM at moderate rates (M2500) may ensure desirable crop yields comparable to higher rates of nutrient application with minimal potential losses relative to higher rates.

Description: Continuous or discontinued manure applications to agricultural soils may impact soil organic carbon (SOC) and water balances because of manure carbon inputs and the potential for manure-induced soil hydrophobicity (SH) and soil water repellency (SWR). A laboratory study was conducted using a long-term (44 yr) field experiment on a clay loam soil to determine the effect of application rate of feedlot manure under dryland (0, 30, 60, and 120 Mg ha-1 wet wt.) and irrigation (0, 60, 120, 180 Mg ha-1) on SOC, SH and SWR. In addition, we compared the effect of 44 yr of continuous annual manure applications (C44) to legacy treatments which had discontinued applications for 14 yr (D14) or 30 yr (D30). Laboratory measurements were conducted on air-dried and sieved ( 1.95) SWR. Manure application rate had a significant (P ≤ 0.05) and positive effect on SOC and SH, and both followed an exponential model. In contrast, RI had a negative response to application rate under dryland and had no response under irrigation. Overall, positive responses of SOC and SH to application rate supported our hypothesis, but it was not supported for RI. The hypothesis of greater SOC, SH, and RI for continuous versus discontinued treatments was also supported for SOC and SH, but not for RI.

Description: Soil water percolation is an important process required to meet plant water needs, determine soil water storage, and affect soil water quality in riparian buffer strips. However, the effects of plant roots on soil percolation in riparian buffer strips are not totally understood, and contradictory results have been carried out on the effects of the root system on soil percolation rates. This study aimed to investigate soil percolation in natural grasslands and evaluate the relationships between root morphological characteristics and percolation rates. Path analysis was used to provide information on the relative contribution of root characteristics on soil percolation rates. Three mixed grasslands (Imperata cylindrica + Phragmites australis, Imperata cylindrica + Cynodon dactylon, Imperata cylindrica + Juncellus serotinus) were selected in the Yellow River wetland natural reserves of Zhengzhou. Soil percolation rates (initial, average and steady infiltration rates) were measured by using double-ring methods, and plant root morphological characteristics were analyzed. Soil percolation rates and plant root characteristics parameters of Imperata cylindrica + Phragmites australis and Imperata cylindrica + Cynodon dactylon were higher than those of Imperata cylindrica + Juncellus serotinus. Initial percolation rate of Imperata cylindrica + Phragmites australis and Imperata cylindrica + Cynodon dactylon at 0-10cm depth was 58.06% and 95.55% higher than that of Imperata cylindrica + Juncellus serotinus, respectively. Percolation rates had a significant positive correlation with root characteristic parameters, and the main factor controlling soil percolation rates was root volume density. Mixed natural grasslands with more root volume density improved soil infiltration and percolation rates.

Description: The quality of the cement-treated soil columns is normally assured based on the unconfined compressive strength qu of core samples. qu of core samples varies spatially and the statistical parameters of qu are adopted in quality assurance procedures. The statistical parameters of qu evaluated from the core sample strengths have a statistical uncertainty depending on the statistical sample size. The present study investigates the influence of the statistical sample size on the evaluation of overall strength of a cement-treated soil column. A probabilistic framework in which a Bayesian inference analysis and a finite element method analysis are incorporated is used to calculate the overall strength while simultaneously considering the statistical uncertainty and spatial variability of core strength. The probabilistic framework is briefly described and a parametric analysis is performed to investigate the influence of the statistical sample size on the evaluation of the overall strength of a full-scale column. The numerical results show that the sample size and spatial correlation influence the variability of the overall strength, and the influence can be reasonably described using an equivalent number of independent data.

Description: Renewable materials including coir, biochar and composts are investigated worldwide in the horticultural industry to partially substitute peat in growing media. In this study, we assessed the effects of biochar and vermicompost as partial substitution of peat, and compared these peat-based growing media with coir in terms of NH4+-N and NO3--N content, CO2-C and N2O-N emissions and their microbial biomass carbon (MBC) and nitrogen (MBN). Six growing media mixtures (peat; peat+biochar 9:1 v/v; peat+vermicompost 9:1 v/v; coir; coir+biochar 9:1 v/v; coir+vermicompost 9:1 v/v) replicated three times were incubated in growth chambers during a 60-days period. At day 0 of incubation (DAI), peat amended with biochar retained around 12.81% of NH4+-N compared with peat alone. The concentrations of NO3--N peaked at 275 mg kg–1 at 33 DAI for peat and 552 mg kg–1 at 46 DAI for coir amended with vermicompost. The substitution of peat with biochar resulted in large CO2-C (2070 µg CO2-C g–1 dry weight (dw)) and N2O-N (62.78 µg N2O-N g–1 dw) emissions, but not coir. The substitution of coir with vermicompost increased N2O-N emissions at a much lower level (47.53 µg N2O-N g–1 dw) than peat (111.82 µg N2O-N g–1 dw). Our results showed that supplements of vermicompost in peat and coir improved N supply which could benefit plant growth, while substituting part of peat with biochar increased CO2-C and N2O-N emissions. In contrast, no effect of biochar was observed with coir, which is beneficial for the environmental footprint of short-cycle growing crops.

Description: There is an urgent need for brackish groundwater-based irrigation methods to be developed for saline soils that are effective, economically advantageous, and environmentally friendly. The use of both ionized brackish water and polyacrylamide (PAM) might provide such a method. The long-term use of brackish water irrigation can lead to the secondary salinization of soil and, as a consequence, restrict the development of the agricultural economy. Here, we conducted one-dimensional vertical infiltration experiments to examine the effects of ionized brackish water and PAM on soil infiltration characteristics. The result indicated that the water retention of soil first increased and then decreased with the increased in PAM application rates. The maximum water retention of soil was obtained in PAM application of 0.04% for ionized brackish water treatment. Soil water storage for the 0.04% PAM application under ionized brackish water irrigation was the highest and 5.1% higher compared with non-ionized brackish water at a PAM application rate of 0.04%. The ionized brackish water treatment at a PAM application rate of 0.04% improved the desalinization efficiency by 2.3% compared with non-ionized brackish water treatment. Thus, ionized treatment and PAM application are effective for improving the characteristics of soil water and salt transport and permit the safe use of brackish groundwater for irrigation.

Description: Depositional ages and provenance of metasedimentary rocks provide constraints on the architecture of the interface between the Slave and Rae cratons and processes related to the Thelon Orogen. Clastic rocks analysed from the central Thelon tectonic zone are Paleoproterozoic in age and not remnants of the Archean Yellowknife Supergroup (Slave Province), as originally considered. Two assemblages are recognized. An older clastic assemblage deposited after 2.09 Ga contains detrital zircon age modes of 2.3 and 2.17 Ga, with subordinate Neoarchean and Paleoarchean detritus. Its deposition is interpreted to predate Thelon magmatic activity given that (1) it lacks ca. 2.01–1.97 Ga detritus of Thelon magmatic origin, and (2) correlative clastic rocks occur as inclusions in Thelon plutons and contain ca. 2.0 Ga metamorphic monazite. This assemblage is correlative with both the Mary Frances and Rutledge River groups, establishing a 〉800 km long basin at ca. 2.1 Ga that received detritus from the western Rae and (or) Buffalo Head terrane(s). Separation from the Slave craton at this time is consistent with the absence of any Slave-affinity detritus. A younger assemblage deposited after 1.95 Ga and prior to 1.91 Ga contains mainly 2.02–1.95 Ga detrital zircon, age modes comparable with adjacent Thelon convergent-margin plutonic rocks. The younger assemblage records deposition of the uplifted and eroded Thelon magmatic arc in an intermontane or foreland basin setting during the later stages of post-collisional convergence. These U–Pb zircon data support a tectonic model for western Laurentia that reconciles differences between the Thelon and Taltson magmatic zones involving ca. 2.1 Ga rifting, ca. 2.01–1.97 Ga convergence, followed by

Description: Predicting the soil available nitrogen (N) to grain corn over a growing season in humid temperate regions is the key for improving fertilizer N recommendations. The objective of this study was to evaluate a suite of soil-N tests to predict soil N availability to grain corn over two growing seasons at 13 individual sites with long-term history of synthetic N fertilization in Ontario, Canada (13 site-years). At each site, fertilizer N was applied at various rates (0-224 kg N ha-1) to determine the crop response to N fertilizer, relative yield (RY) and the most economic rate of N (MERN). Across the entire dataset, water-extractable mineral N (WEMN) was the only soil test that strongly correlated to both RY (r = 0.74**) and MERN (r = -0.56*) indicating that in grain corn fields with long-term history of N fertilization, mineral forms of N in soil solution can be used for fertilizer N recommendations in southern and eastern Ontario. We also provide evidence that grouping soils based on clay content could further refine fertilizer-N recommendations for grain corn in Ontario. A multi-year validation of the WEMN test with more field sites and development of a fertilizer recommendation table for this soil test are recommended.

Description: Recent researches on the behavior of gravelly sands advocate for the use of skeleton void ratio to characterize their density state. Skeleton void ratio corresponds to the void ratio of grains constituting the stress-bearing skeleton. However, such a void ratio relies on parameters difficult to determine in practice, such as the fraction of fine grains that take part actively in the load bearing skeleton. Also, it fails to consider the effect of Grain Size Distribution (GSD) of gravel and sand grains. Therefore, the skeleton void ratio index introduced by Chang et al (2015) is revisited to account for the effect of GSD of both gravel and sand grains. Two semi-empirical equations are developed in this paper to connect GSD parameters with skeleton void ratio parameters. The validity of the proposed equations has been checked for a particular class of gravelly sand materials. A series of specially-designed drained triaxial tests on gravelly sands were then conducted. Test results show that it is essential to consider the effect of GSD when using skeleton void ratio index. It also verifies the effectiveness and applicability of the proposed updated skeleton void ratio, which shows advantages in characterizing critical state lines of gravelly sands.

Description: The island of Cyprus constitutes a fragment of southern Anatolia separated from the mainland by left-oblique transtension in late Cenozoic time. However, a geological framework of offset features of the south-central Anatolia, for comparison of Cyprus with a source region within and west of the southeastern Anatolian suture zone, has not yet been developed. In this paper, I enumerate, describe, and compare a full suite of potentially correlative spatial and temporal elements exposed in both regions. Northern Cyprus and south-central Anatolia have identical tectonostratigraphic units. At the base of both belts, crop out ophiolitic mélange-accretionary complex generated during the northward subduction of the NeoTethyan Oceanic lithosphere from the Late Cretaceous until the end of middle Eocene. The nappes of the Taurus carbonate platform were thrust above this internally chaotic unit during late Eocene. They began to move as a coherent nappe pile from that time onward. An asymmetrical flysch basin was formed in front of this southward moving nappe pile during the early Miocene. The nappes were then thrust over the flysch basin fill and caused its tight folding. Cyprus separated from Anatolia in the Pleistocene-Holocene when, transtensional oblique faults with dip-slip components caused the development of the Adana and Iskenderun basins and the separation of Cyprus from Anatolia.

Description: Water availability and pH are important factors to consider to determine the suitability of a material for use as a growing medium. Unfortunately, most horticultural substrates are characterized by their water repellency. This is the case with peat moss which is hydrophobic and acidic. Synthetic surfactants are required to improve its wettability. In this study, a combination of phosphorylated wood pulp fibers (FLP) and zeolite is proposed as a substitute to surfactants to increase the wettability of peat moss in the presence of lime, an additive generally used as fertilizer or pH regulator. Results show that lime reduces the water retention capacity of FLP. However, the addition of 15% zeolite to the peat moss/FLP system increases the pH and water retention of the substrate. The negative effect of the presence of 1 wt. % lime on the water retention of the peat moss/FLP mixture was corrected by zeolite addition. Optimal conditions were obtained at 10% zeolite for the two types of lime tested with favorable pH and water retention capacity values. Zeolite was shown to have a higher affinity than FLP for calcium ions preventing the detrimental interaction between FLP and calcium ions.

Description: Understanding of the risk of phosphorus (P) loss to the environment is crucial to monitor soil P and implement policies for P management. We assessed P sorption characteristics and adapted a P saturation index (PSI) for silage corn and blueberry fields in south coastal British Columbia (BC), Canada. We used 284 composite soil samples with contrasting P levels collected from eight silage corn and 23 blueberry fields across south coastal BC. The P sorption maximum (Smax) varied between 982 and 2532 mg P·kg−1 and was influenced by aluminum concentration and organic matter content. The degree of P saturation was related to water-extractable P (Pw) by a quadratic regression with R2 = 0.85. A critical Pw = 3.7 mg·kg−1 was established across the two cropping systems. The silage corn fields with pH 〉 5.5 had critical PSI value of 10.4%, and blueberry fields with pH 

Description: The Andaman Ophiolite of south-eastern India is located on the outer arc of the Andaman-Java subduction zone. It is represented by thrust slices formed in the Mesozoic Neo-Tethyan Ocean. Lithologically, it consists of dismembered mafic and ultramafic rocks and associated oceanic pelagic sediments. The present study focuses on the mafic cumulate rocks of the Andaman Ophiolite preserved in the Kodiaghat and the Mundapahar area of the South Andaman Island. The mafic cumulates are represented by olivine-bearing and olivine-free gabbros. The sequence of crystallisation in the gabbros is olivines (Fo~80) ± chromian spinels (Cr# 59 - 57), plagioclases (An95−61), clinopyroxenes (Mg# = 89 - 82) and amphiboles (Mg-hornblende, edenite and pargasite). Major oxide and trace element whole rock geochemistry and mineral compositions are consistent with a hybrid signature of Island Arc Tholeiite (IAT) - Mid Oceanic Ridge Basalt (MORB). Geochemical modelling shows that trapped melt fractions of 0 – 20 % can produce the observed trace element signatures of these gabbros. Our findings suggest that the gabbroic cumulates of the Andaman ophiolite were formed in an oceanic back-arc and oceanic arc setting developed in the Neo-Tethyan oceanic domain between the Indian and the Burmese plates during Late Cretaceous age.

Description: Physical building vulnerability to debris flows is defined as the potential damage degree of buildings for a given debris-flow intensity. In this paper, the physical characteristics on both debris flow intensity and building response are considered. Uncertainties in building capacity and debris flow intensity are explicitly quantified to evaluate the damage probability of a typical reinforced concrete building subject to debris flow impact. Four damage states with clear failure mechanisms are defined using multi-source information from field observations, numerical simulation and expert experience. Two series of fragility models have been proposed based on practical debris-flow impact pressure models. Several debris flow intensity measures are investigated. A better indication can be provided using the intensity measure that represents specific failure mechanism, for example, impact force (hv2) for force-dominated failures or overturning moment (h2v2) for moment dominated failures, where h and v are debris flow depth and velocity, respectively. The corresponding fragility surfaces best express the potential building damage. The intensity thresholds in the proposed fragility curves are consistent with those in empirical vulnerability curves. The methodology presented in this paper promotes the vulnerability assessment using physics based modeling, leading to a more reliable evaluation of building damage caused by debris flows.

Description: Climate change is having myriad effects on Arctic marine ecosystems and food webs. Anadromous Arctic Char, Salvelinus alpinus, feed intensively at sea during summer. In Cumberland Sound, NU, there has been a recent increased availability of a forage fish, Capelin. To investigate changes over time in Arctic Char foraging, we assessed Arctic Char trophic niche from 2002 to 2011 using stomach content analysis and stable isotope analysis (δ13C and δ15N) of muscle tissue from two river/lake systems, Isuituq and Kipisa. We also compared population characteristics by calculating Fulton’s condition factor (K) and by fitting von Bertalanffy growth curves with length-at-age data. Results revealed Capelin newly present in the diets of Arctic Char in 2011, describing a shift from a primarily invertebrate-based to a fish-based diet. No trend in δ15N (del 15N) over time suggests the trophic level of Arctic Char has not changed; however, the δ15C (del 15C) for both systems converged in 2011 on a value suggestive of feeding on Capelin. Growth curves and length-at-age analyses suggest that foraging on Capelin may have increased individual growth. Changes in the growth and condition of Arctic Char in this region could have significant economic and cultural implications.

Description: Critical analysis of induced earthquake occurrences requires comprehensive datasets obtained by dense seismographic networks. In this study, using such datasets, I take a detailed investigation into induced seismicity that occurred in the Montney play of northeast British Columbia, mostly caused by hydraulic fracturing. The frequency-magnitude distribution (FMD) of earthquakes in several temporal and spatial clusters, show fundamental discrepancies between seismicity in the southern Montney play (2014-2018) and the northern area (2014-2016). In both regions, FMDs follow the linear Gutenberg-Richter (G-R) relationship for magnitudes up to 2-3. While in the southern Montney, within the Fort St. John graben complex, the number of earthquakes at larger magnitudes falls off rapidly below the G-R line, within the northern area with a dominant compressional regime, the number of events increases above the G-R line. This systematic difference may have important implications with regard to seismic hazard assessments from induced seismicity in the two regions, although caution in the interpretation is warranted due to local variabilities. While for most clusters within the southern Montney area, the linear or truncated G-R relationship provide reliable seismicity rates for events below magnitude 4, the G-R relationship underestimates the seismicity rate for magnitudes above 3 in northern Montney. Using a well-located dataset of earthquakes in southern Montney, one can observe generally that 1) seismic productivity correlates well with the injected volume during hydraulic fracturing and 2) there is a clear depth dependence for the G-R b-value; clusters with deeper median depths show lower b-values than those with shallower depths.

Description: Steep-creek beds are macroscopically rough. This roughness causes channelised flow material to decelerate and dissipate energy, which are accounted for by depth-averaged mobility models (DMM). However, practical DMM implementations do not explicitly account for grain-scale basal interactions which influence macroscopic flow dynamics. In this study, we model flows using physical tests with smooth and macroscopically rough bases, and hence evaluate Discrete Element Method (DEM) and DMM models. A scaling effect is identified relating to roughened beds: increasing the number of grains per unit depth tends to suppress dispersion, such that small-scale flows on smooth beds resemble large-scale flows on roughened beds, at least in terms of bulk density. Furthermore, the DEM shows that rougher beds reduce the peak bulk density by up to 15% compared to a smooth bed. Rough beds increase the vertical momentum transfer tenfold, compared to smooth ones. The DMM cannot account for density change or vertical momentum, so DMM flow depths are underestimated by 90% at the flow front and 20% in the body. The Voellmy model implicitly captures internal energy dissipation for flows on rough beds. The parameter ξ can allow velocity reductions due to rough beds observed in the DEM to be captured.

Description: Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, applied and assessed standardized protocols to measure tundra herbivory at three spatial scales: plot, site (habitat), and study area (landscape). The plot and site-level protocols were tested in the field during summers 2014-2015 at eleven sites, nine of them comprising warming experimental plots included in the International Tundra Experiment (ITEX). The study area protocols were assessed during 2014-2018 at 24 study areas across the Arctic. Our protocols provide comparable and easy-to-implement methods for assessing the intensity of invertebrate herbivory within ITEX plots and for characterizing vertebrate herbivore communities at larger spatial scales. We discuss methodological constraints and make recommendations for how these protocols can be used and how sampling effort can be optimized to obtain comparable estimates of herbivory, both at ITEX sites and at large landscape scales. The application of these protocols across the tundra biome will allow characterizing and comparing herbivore communities across tundra sites and at ecologically relevant spatial scales, providing an important step towards a better understanding of tundra ecosystem responses to large-scale environmental change.

Description: This paper presents the horizontal bearing characteristics of piles in coral sand and silica sand from comparative experimental studies. A total of 6 model piles with different diameters are tested. The horizontal bearing capacity, deformation characteristic, bending moment, p-y curve, the change in soil horizontal pressure, as well as the particle breakage behaviour of coral sand are investigated. The results show that, in coral sand foundation, the horizontal bearing capacities of piles and the increments of soil horizontal pressures are obviously greater than those in silica sand. Accordingly, the lateral displacement, the rotation of pile head, the bending moment and the corresponding distribution depth in coral sand are significantly smaller than that in silica sand. The p-y curves indicate that the horizontal stiffness of coral sand is greater than that of silica sand. Remarkably, the breakage behaviour of coral sand is mainly distributed in the range of 10 times pile diameter depth and 5 times pile diameter width on the side where the sand is squeezed by pile. Furthermore, in coral sand, the influence of pile size is more pronounced, the squeezing force generated by pile spread farther and its influence range is larger compared to those in silica sand.

Description: High resolution topographic modeling has become more accessible due to the development of Structure from Motion (SfM) image matching algorithms in digital photogrammetry. Large archival databases of historical aerial photographs are available in university, public, and government libraries, commonly as paper copies. The photos can be in poor condition (i.e. deformed by humidity, scratched, or annotated). In addition, the negatives, as well as metadata, may be missing. Processing such photos using classic stereo-photogrammetry is difficult and, in many instances, impossible. SfM can be applied to these photosets to access the valuable archive of geomorphic changes over the past century. In this paper, we illustrate the utility of the SfM technique using 568 digitized vertical aerial photographs of Mount Meager volcano, located in southwest British Columbia, Canada. We use the aerial photographs, which span the period from 1947 to 2006, to track glacier and glacier-landslide interactions on the volcano. Over this period, glaciers have thinned and retreated, interrupted by minor advances in the 1960s and 1970s. Landslides are frequent on the volcano and contribute to debris cover on the glaciers affecting the ablation process. SfM processing of the aerial photographs allowed us to unlock geomorphic information and reconstruct landscape change that would otherwise have been impossible. The results from SfM provide a visually effective way of presenting landscape change to a broad public audience, as a form of virtual geoheritage. The approach can thus be broadly applied in scientific and professional practices for improving land planning and hazard management.

Description: Warmer atmospheric temperatures (eT) will increase plant nutrient uptake, and elevated atmospheric CO2 (eCO2) is expected to enhance plant growth, whereas a multicomponent eTeCO2 effect should also be beneficial for agroecosystems. Our goal was to understand if single- (eT, eCO2) or multicomponent (eTeCO2) climate effects, predicted for southern Ontario, Canada, will affect soybean and soil properties differently when soil is amended with manure and biochar (MB) or with manure, nitrogen (N) fertilizer, and biochar (MNB) compared with the addition of manure and N fertilizer (MN). We hypothesized that biochar regulates climate effects and causes soybean and soil properties to be similar to ambient climate conditions than soil without biochar. However, soil amended with biochar functioned independently of single- or multicomponent climate effects. Soybean pod and shoot biomass, shoot height, and shoot:root ratio were greater (p 

Description: Long term cattle manure applications build up nutrient pools and can lead to trace element enrichments in soils. The objectives of this study were to evaluate Cu and Zn loadings in the soil during continuous annual cattle manure applications and determine the time required for soil to return to its pre-manure available Cu and Zn levels after manure is discontinued. The manure application rates were 0, 30, 60, and 90 Mg ha-1 for rainfed and 0, 60, 120, and 180 Mg ha-1 (wet weight) for irrigated plots. While manure was applied for 45 years in some plots, applications were terminated in one subset of treatments after 14 years and in another subset after 30 years to study legacy effects after 31 and 15 years, respectively. Soil samples were collected in the fall of 2003, 2008, 2013, and 2018 and analyzed for available Cu and Zn. Crops were grown in all years continuously with Cu and Zn concentrations measured in both silage and grains harvested. The regression model developed using data collected suggests long legacy effects with recovery time to pre-manure levels ranging from 10-20 years for Cu and 23-41 years for Zn at irrigated and 10-24 for Cu and 21-32 years for Zn under rainfed, respectively. Long term applications of cattle manure could lead to accumulation of Cu and Zn, creating long-lasting legacy effects in soils with the increased environmental risk of leaching to groundwater

Description: Microorganisms mediate soil organic carbon (SOC) turnover, and microbial residues contribute a significant portion to SOC storage in temperate agroecosystems. However, little is known about the direct effect of temperature on microbial residues associated with SOC sequestration/decomposition. We assessed microbial residue dynamics in a 28 d incubation conducted at four temperatures (5, 15, 25, and 35 °C). Microbial residues did not change with time from 5 to 25 °C. However, at 35 °C, fungal residues decomposed significantly with time, and the decomposition rate was higher than SOC. Considering the important contribution of fungal residues to stable-C pool, our findings indicated warming may be detrimental to C stability in this temperate soil.

Description: Impact loads generated from the dynamic effect of passing trains can exacerbate the degradation level of ballast aggregate of railway track. To diminish the induced impact loads, the use of crumb rubber (CR) in the ballast course is characterized as a well-established procedure related to the modification of utilized material. Nonetheless, more in-depth assessments of size and percentage of CR particles combined with ballast aggregate are still required. The present study evaluates the influence of size and content of CR particles used for degradation reduction of ballast aggregate subjected to impact loading. For this purpose, a large-scale impact loading test is carried out on prepared specimens of aggregate by considering the initial gradation, subgrade condition, as well as the size and content of CR particles. The results indicate less ballast degradation for a higher percentage of CR particles. Meanwhile, the enhancement of rubber modified ballast against deterioration is further highlighted in the case of rigid subgrade. In addition, incorporation of larger-sized CR particles (12.5–25 mm) in a ballast specimen comprising more uniform gradation of aggregate can more effectively diminish the amount of degradation. Nevertheless, using smaller-sized CR particles (4.75–9.5 mm) for a ballast sample consisting of a broader range of sizes can better improve resistance against degradation.

Description: Landslides are a risk to buried gas pipeline infrastructure, but these risks are particularly difficult to assess given the complex nature of landslide movements. This paper presents of portion of research conducted at the University of Manitoba where gas pipelines within active landslide areas were monitored over a four-year period. Two locations were examined in Western Manitoba within the Assiniboine river valley where a shallow natural gas pipeline runs parallel to the valley slope. A field investigation and monitoring program was undertaken where surficial ground movements and soil and pipe temperatures and pipe strains through strain gauges were measured. Monitoring results identified soil near the pipeline does not freeze, and ground movements are

Description: Mining at greater depths can lead to stress-induced failure, especially in areas of high horizontal in-situ stress. The induced stresses around the opening are known to be in a poly-axial stress state where, σ_1≠ σ_2≠ σ_3 with special case of σ_3= 0 and σ_1, σ_2 ≠ 0 at its boundary. The conventional triaxial testing does not represent the actual in-situ strength of the rock in regions of high horizontal stress, as it ignores the influence of intermediate principal stress (σ_2). The typical poly-axial testing (biaxial and true-triaxial tests) of intact rock mostly requires sophisticated and expensive loading systems. This study investigated the mechanical behavior of intact rock under a poly-axial stress state using a simple and cost-effective design. The apparatus consists of biaxial frame and a confining device. The biaxial frame has two platens that apply equal stress in both directions (σ_1=σ_2) on a 50.8 mm cubical specimen when placed inside the uniaxial loading device. The confining device performed separate biaxial tests under constant intermediate principal stress (σ_2 = constant) and true-triaxial tests when used along with the biaxial frame. This study then compared the failure modes and peak strength of Berea Sandstone specimens with other biaxial/triaxial devices to validate the design of the poly-axial apparatus. We also performed uniaxial tests on both standard cylindrical samples and prismatic specimen of different slenderness ratios. These tests provided a complete understanding of the failure mode transition from standard uniaxial compressive tests to triaxial stress conditions on cubical specimen. Additionally, this study determined best-fitted strength envelopes for biaxial and triaxial stress state. Based on regression analysis, we found a quadratic polynomial to be a good fit to biaxial strength envelope. For true-triaxial strength envelope, we found the 3D failure criterion by Nadai (1950) to be a good fit with R^2 of 0.964

Description: Annual removal of tobacco residues and insufficient input of organic materials have exacerbated total organic carbon (TOC) depletion and soil degradation in a tobacco field in the Huanghuai area. Straw residue and biochar application may be effective ways to increase TOC accumulation and improve soil fertility. In this field experiment, wheat straw (WS) and wheat-straw derived biochar (BC) with mineral fertilizer were compared to mineral fertilizer alone (CK) and we assessed their effects on soil organic carbon fractions, enzyme activities, and nutrients in Shandong Province, China during 2016 and 2017. At 0–20 cm depth, the WS treatment had a greater overall effect on the measured soil properties. Compared with the control, the WS treatment significantly increased the concentrations of microbial biomass carbon (MBC), hot water-extractable carbon (HWC), and permanganate-oxidizable carbon concentrations (POXC; by 252.41%, 107.02%, and 65.53%, respectively); the activities of sucrase, urease, and phosphatase (by 112.52%, 7.81%, and 34.33%, respectively); and the contents of alkaline hydrolysable nitrogen, available phosphorus, and available potassium (by 92.22%, 100.78%, and 10.57%, respectively). Compared with the control, the BC treatment significantly increased TOC content, MBC content, light fraction organic carbon (LFOC) and potassium (TK) concentration (by 74.93%, 86.24%, 153.73%, and 21.92%, respectively). Most soil enzyme activity and nutrient parameters were significantly correlated with MBC. Thus, straw application improved soil fertility by increasing the concentrations of high labile organic carbon fractions (HWC, MBC, POXC), stimulating soil enzyme activities, and releasing more soil available nutrients, and BC addition contributed to the accumulation of TOC, MBC, LFOC, and TK.

Description: Fall-applied manure may have nitrogen (N) fertilizer value for spring-seeded crops. We applied liquid or solid cattle manure to plots on a sandy-loam soil in southern Quebec in fall. The following spring, half of each plot received urea fertilizer before planting the spring cereal crop. Total N content of the spring cereal at tillering, flowering, and maturity was lower in subplots without urea, and yields were up to 183% less in the no-urea subplots, regardless of whether liquid or solid manure was applied in fall. Fall-applied manure did not provide plant-available N to spring cereals under our growing conditions.

Description: Estimating pile group efficiency for open-ended steel piles in small group arrangements is a challenging task for designers. This paper reports on the large-scale experimental campaign performed for the BorWin gamma offshore converter platform, which involved single piles and two-pile group systems on a scale of 1:10. The experimental works included installation, dynamic end-of-driving tests, dynamic restrike tests, and static load tests of a single pile and a pair of two-pile groups in densely compacted, artificially prepared homogeneous sand. The CPT profiles and the blow counts confirmed that the foundation systems are comparable to each other. The experimental results of the single pile system were compared with conventional design methods. Such comparison indicated that CPT-based methods and load-transfer methods are applicable at the considered model scale. The bearing capacity prediction obtained via the CAPWAP method is conservative with respect to the static capacity. A consistent setup effect can be detected by analyzing the complete dynamic loading session. The pile group efficiency for the given foundation system was found to be less than 1.0 at both very small and very large soil strains, while it equaled 1.0 at failure.

Description: Swelling characteristics of compacted bentonite when hydrated with a hypersaline pore fluid (332 g/L total dissolved solids; 6.6 mol/L ionic strength) are reported. The pore fluid mimics the multiple constituents and their concentrations found for the Cobourg limestone of the Michigan Basin and is dominated by sodium (25% mole fraction) with some potassium, calcium, and magnesium (10%, 5%, and 4% mole fractions). Measurements of swell pressure for two sodium bentonites when hydrated under conditions of zero volume increase are reported. Swell pressure reached a peak within 10–30 h from the onset of hydration, followed by a continual decrease over 1 year of testing from chemical interaction between the bentonite and pore fluid. After 1 year, the swell pressure of the MX-80 bentonite tested decreased by a factor of nine relative to the peak swell pressure with deionized water when the dry density was 1.6 Mg/m3. Swell pressures increased as dry density increased. However, chemical interactions appear to have more influence on swell pressure than density for the pore fluid examined as a swell pressure of just under 1200 kPa was measured for MX-80 after 1.8 years of hydration when compacted to the highest dry density of 1.8 Mg/m3 examined.

Description: Driven cast-in-situ (DCIS) piles are classified as large displacement piles. However, the use of an oversized driving shoe introduces additional complexities influencing shaft resistance mobilisation, over and above those applicable to preformed displacement piles. Therefore, several design codes restrict the magnitude of shaft resistance in DCIS pile design. In this paper, a series of dynamic load tests was performed on the temporary steel driving tubes during DCIS pile installation at three UK sites. The instrumented piles were subsequently subjected to maintained compression load tests to failure. The mobilised shear stresses inferred from the dynamic tests during driving were two to five times smaller than those on the as-constructed piles during maintained load testing. This was attributed to soil loosening along the tube shaft arising from the oversized base shoe. Nevertheless, the radial stress reductions appear to be reversible by the freshly-cast concrete fluid pressures which provide lower-bound estimates of radial total stress inferred from the measured shear stresses during static loading. This recovery in shaft resistance is not recognised in some European design practices, resulting in conservative design lengths. Whilst the shaft resistance of DCIS piles was underpredicted by the dynamic load tests, reasonable estimates of base resistance were obtained.

Description: Animal distribution and movement facilitate energy- and nutrient-transfer within and between regions, thus influencing ecosystem structure and function. Ringed seals (Pusa hispida) have been observed making sustained, extensive migrations (〉 1000km) in the western Canadian Arctic, but observations of their movements from the eastern Canadian Arctic are limited. We equipped 12 ringed seals with satellite telemetry tags in Resolute Bay (n = 7; 2012, 2013) and Tremblay Sound (n = 5; 2017, 2018), Nunavut, to monitor their movements, behavioural states, and diving behaviour from late summer until their spring moult. Six tags transmitted into winter and recorded long-distance movements to southeastern Baffin Island, with three seals travelling through central Baffin Bay (3608 ± 315 km; maximum 4226 km), while three travelled along the Baffin Island coastline (3674 ± 655 km; maximum 4872 km). Seals that travelled through central Baffin Bay made shallower dives (25.4 ± 1.1 m) than those that travelled near the coast (100.0 ± 4.1 m, respectively). Results provide new information on the variability, scales, and pathways of movement and diving behaviour of eastern Canadian Arctic ringed seals. This new knowledge can be used to inform spatial conservation and management priorities of this ecologically- and culturally-important species.

Description: This paper presents a novel framework of modeling crushable granular materials under mechanical loadings based on the discrete element method (DEM). The framework is featured with the construction of the one-to-one model in which every particle in a physical experiment has its own numerical twin and allows the modeling of irregular shaped fragments during the continuous breakage process. First, image processing techniques and spherical harmonic (SH) analysis were adopted, respectively, to segment and label particles and to construct a one-to-one model mathematically in DEM. Then, a particle crushing criterion based on the maximum inter-particle contact force was used to predict the crushing events, showing fitting results that agreed very well with a large number of single particle crushing tests. Next, a statistical approach for the generation of particle fragmentation modes of a given type of sand particles based on the principal component analysis (PCA) was proposed. The aim of the PCA was to analyze the statistical trends of the coefficient matrix, which was composed of the SH coefficients of all the particles involved in the analysis. Finally, a successful modeling of a particle crushing event was achieved by replacing the particle, which was judged by the crushing criterion to undergo crushing, with a few sub-particles chosen randomly from a specific fragment template constructed using the micro-computed tomography (micro-CT) data.

Description: Biochar has potential to sequester carbon and mitigate greenhouse gas emissions, and it may also contribute nutrients for plant growth in temperate climates. Nutrient availability in biochar-amended soil was assessed in a 338-d incubation study. The clay soil prepared with 4% w/w (dry basis) compost or without compost, then amended with wood-based biochar made at different pyrolysis temperatures (maple bark [Acer saccharum] at 400°C [M400], 550°C [M550] and 700°C [M700]) on a dry-rate basis of 5% (w/w). After moistening the soil mixture to 44% volumetric soil water content (equivalent to 70% water-filled pore space), soil mixtures were incubated in the dark at 22°C. Soil was sampled at days 9, 16, 23, 44, 86, 23 170 and 338 of the incubation. Biochar amendment increased the Mehlich-3 P, K, Ca, Mg and Cu concentrations, and reduced the Mehlich-3 Al and Fe concentrations at each sampling date, and M400 had the most significant effect on Mehlich-3 extractable nutrient concentrations. Compost addition also increased the amounts of extractable nutrients. These results suggested that M400 and carbon-rich compost promoted microbial growth and mineralization in amended soil. In addition, soil mixed with compost and amended with biochar had more Mehlich-3 extractable K than when compost or biochar were applied alone, probably due to greater growth and activity of soil K-solubilizing microorganisms. Overall, our study indicated that co-application of wood-based biochar and compost could improve soil fertility in temperate regions by increasing the availability of most plant macronutrients and micronutrients.

Description: The depth of mixing layer is one of the important parameters which cannot be assigned a constant value affected by many factors in the slope runoff. The objective of this study was to investigate the effect of slope length and underground biomass on slope runoff, solute transport processes, as well as mixing layer depth. In this study, the experimental plots with the four slope lengths (5, 10, 15, and 20 m) and a width of 2 m were built on the slope with the gradient of 20°. In addition, the plots with the millet or wheat planting were built on the slope. The change of runoff and solute transport was analyzed through simulated rainfall experiments and then to estimate mixing layer depth. The results showed that the runoff rate decreased and more runoff seeped into the slope soil with increasing slope length. Increasing underground biomass also promoted greater rainfall infiltration into the soil. The increase in slope length increased the concentration of solute in runoff, but more underground biomass reduced the nutrients transported with runoff. The effective mixing depth increased with an increase in slope length, but effective mixing depth decreased with increased underground biomass. The modified expression of the equivalent mixing model under different slope lengths and underground biomass could accurately describe the solute transfer process in runoff when compared with complete mixing model and incomplete mixing model based on exponential functions. This research provided a reference for improving the application of mixing layer models in the slope management.

Description: We measured community-level traits of vascular plants, lichens and bryophytes in an alpine Dryas octopetala heath in Finse, Norway, after nearly two decades of experimental warming by open top chambers. We hypothesized that under warming 1) vascular plant traits would shift from resource conservative towards more resource acquisitive, and 2) lichen and bryophyte traits would shift to those associated with drier conditions, due to increased evapotranspiration. Both hypotheses were not supported, as vascular plant nitrogen concentration decreased while carbon to nitrogen ratio increased with warming, indicative of a less resource acquisitive strategy, and lichen specific thallus area and water holding capacity (WHC) were unresponsive. Bryophyte specific shoot length increased, and carbon concentration and WHC tended to decrease under warming, concurrent with increased vegetation height and litter cover indicating stronger competition from vascular plants. Intraspecific variation was most important for vascular plant and lichen traits, while species turnover was the main driver of bryophyte trait variation. This indicates that bryophytes may be affected more strongly by future warming than vascular plants and lichens in our study system. We highlight the importance of studying traits of different primary producer groups simultaneously, as they may respond differently to the same environmental changes.

Description: Farm soil tests are common decision support tools employed by regulatory agencies and farmers to manage nutrients in an economical and environmentally sustainable way. The complex interplay between the local environment and locally relevant crops makes soil testing, and critically soil-test based recommendations, site-specific. Newfoundland and Labrador (NL) has a relatively small but rapidly growing commercial agriculture, mainly on lands converted from the boreal forest over the last 80 years. A first step towards developing locally calibrated fertilizer recommendations is understanding current practices. For this, we examined regular farm soil test reports and associated recommendations for Newfoundland (Nfld). Following a request distributed to 167 farmers, 1503 soil tests were obtained from 32 farms. While tests exemplify the gamut of crops in Nfld, more than half were from forage and mixed forage fields in western Nfld, representing dairy farms. Results show that even in the absence of more comprehensive site analyses, an investigative survey of farm tests may be employed to recognize possible environmental and economic inefficiencies of local cropping systems, including regional and crop type-driven differences, for both nitrogen (N) and phosphorus (P) fertilization. Soil-test based identification of possible N and/or P inefficiencies and associated crop and regional particularities, including excess fertilization, can be employed to devise targeted research for improved, preventative decision tools to increase the sustainability of Nfld agricultural systems.

Description: The structural performance and soil-structure interaction mechanism of a 7.3 m span three-sided culvert with flat top slab (TSC) are investigated through field monitoring and numerical analyses. The culvert was instrumented with 6 pressure cells and 14 strain gauges. Data were collected during and after construction. Two-dimensional finite element models were verified against the field measurements. The verified numerical models were then employed to evaluate the effects of the foundation soil condition (yielding or non-yielding) on the applied earth pressures along the culvert profile and the induced straining actions at the base of the culvert’s sidewall. Moreover, the structural performance of TSCs at the ultimate loading condition has been evaluated from the numerical model. The results indicated that for TSC supported on yielding foundation soil, significant bending moment develops at the sidewall base and that the assumption of hinged connection at the base is only realistic for the case of TSCs supported on rock (non-yielding foundation). In addition, the precast unit width was found to have minimal influence on the failure mechanism and the ductility of the precast unit. Finally, failure may occur at a lower backfill height for the case of non-yielding foundation relative to the case of yielding foundation.

Description: Anthrosols refers to anthropic soils of high fertility in general, but the concentration of these nutrients may vary according to the occupation of indigenous people in the past or due to current soil use. This study aimed to evaluate the spatial variability of the chemical attributes of the soil in areas of guandu bean production and pasture and to compare with natural forest systems on Anthropogenic dark earth (ADE). For this assessment, 88 sampling points were selected in the area with natural forest vegetation and pasture and 90 sampling points in an area of guandu bean production. Soil samples were collected from layers 0.00-0.05, 0.05-0.10 and 0.10-0.20 m. Chemical analyses of the soil were conducted to determine organic matter, pH, Aluminium (Al3+), soil acidity (H+Al), phosphorus (P), potassium (K+), Calcium (Ca2+), Magnesium (Mg2+), cation exchange capacity (CEC), sum of bases (SB) and base saturation (V%). Data were analyzed using descriptive statistics and geostatistics to sample range, sample density was estimated for each attribute. Guandu bean showed high content of soil organic matter in relation to pasture in the superficial layer (0.00-0.05 m). Based on sample density, lower variability and higher spatial continuity were observed for guandu bean in relation to pasture and natural forest in the layers of 0.00-0.05 and 0.05-0.10 m. It was found that the use and continuous management of ADE’s areas alter the content and distribution of soil fertility and in some cases may even improve chemical attributes when compared to areas not used with agricultural crops.

Description: The market for small fruits (grapes, blueberries, strawberries, and raspberries) is valued at more than CAD100 million per year in Quebec, Canada. Wood-based biochar is an amendment that improves soil quality, which may boost small fruit growth and production. The objective of this research was to determine if wood-based biochar could increase the yield and quality of grape, blueberry, strawberry, and raspberry in southern Quebec. We evaluated the fruit yield as well as the quality parameters like average fruit weight, fruit firmness, color, juice pH, total soluble solids, total phenolic content, and antioxidant activity. Field trials were established on commercial farms with grape, blueberry, strawberry, and raspberry production systems in plots that received wood-based biochar and no biochar in spring (April to May). Small fruits were harvested at their ripening stage for yield and quality evaluation in fall (July to October). Biochar application did not improve yield and quality parameters of small fruits except it gave a marginal higher yield of grape (3.7 vs. 4.4 t ha-1, P = 0.08) and a higher average fruit weight of strawberry (11.9 vs. 13.2 g, P 〈 0.05). There was no difference in the quality of the fruit from biochar-amended and control plots in the first year of biochar application, possibly because the quality parameters are affected more by weather conditions, handling, and storage than by soil quality. This work suggests that wood-based biochar (

Description: Nanoparticles with high reactivity can be applied as amendments to remediate soil metal contaminations by immobilizing toxic elements. Nano-oxides of Fe have been studied but Al and Ti nano-oxides have not been tested for their remediation capacity of toxic metals. The potential of synthesized iron (Fe-O), aluminum (Al-O), and titanium (Ti-O) nano-oxides for stabilizing Cd, Pb, and Zn in mine spoil (Chat) and contaminated soil was compared using adsorption studies and a greenhouse experiment. Chat and soil were amended with nano oxides at two rates (25 and 50 g kg-1) and a pot experiment was conducted with sorghum (Sorghum bicolor L. Moench). Leachates were collected twice per week from plant emergence to harvest at maturity and metals were compared against an unamended control. Chat was contaminated with Cd, Pb, and Zn at 84, 1583, and 6154 mg kg-1, and soil at 15, 1260, and 3082 mg kg-1, respectively. Adsorption conformed to the Langmuir linear isotherm and adsorption maxima of metals were in the order of Al-O 〉 Ti-O ≥ Fe-O. Nano-oxides reduced Cd concentration by 28% (Fe-O) to 87% (Ti-O) and Zn concentration by 14% (Fe-O) to 85% (Al-O) in plant tissues compared with unamended Chat. Nano-oxides significantly reduced Cd, Pb, and Zn in leachates and available Cd and Zn in Chat/ soil relative to the respective unamended controls. Nano-oxides can be used to remediate heavy metal contaminated Chat and soil and facilitate plant growth under proper nutrient supplements. Nano-oxides of Al-O and Ti-O remediated metals more effectively than Fe-O

Description: This paper presents an experimental study on the pullout behaviour of inclined shallow plate anchors subject to axial pull in sand. The 1g model tests were performed to examine the effects of anchor inclination and sand-anchor interface conditions on the load-displacement response and the associated failure and deformation mechanisms of plate anchors at various embedment ratios and sand densities. The anchor pullout capacity was found to increase continuously with the load inclination angle to the vertical (), and the increase was more significant for  from º to º. The effect of sand-anchor interface conditions was negligible for horizontal plate anchors (º) but it became increasingly significant at larger inclination angles. The effects of these two factors both decreased with an increasing embedment ratio. Their influences on the failure and deformation mechanisms were measured and analysed using a digital image correlation (DIC) technique. Based on the test data and results available in the literature, a simple empirical method for the prediction of pullout resistance of inclined plate anchors in sand is calibrated and recommended.

Description: Leaf toughness is an important functional trait that confers resistance to herbivory and mechanical damage. We sought to determine how species composition, climate, seasonality, and nutrient availability influence leaf toughness in two types of tundra in northern Alaska. We measured leaf toughness as force to punch for 11 species of Arctic plants in tussock tundra and dry heath tundra at 17 sites distributed along a latitudinal gradient. Rubus chamaemorus and the graminoids occupied opposite ends of the leaf toughness spectrum, with R. chamaemorus requiring the least force to punch, while one of the graminoids, Eriophorum vaginatum, required the most. Leaf toughness increased with mean summer temperature for E. vaginatum and Betula nana, while it declined with warmer temperatures for the other species. Toughness of mature leaves of E. vaginatum did not vary through the growing season but declined significantly after senescence. Application of N and P fertilizer in an experimental site decreased leaf toughness in three species but had no effect on four others. Leaf toughness of four out of five species in dry heath was greater than for the same species in tussock tundra, but there was no difference in community-weighted mean toughness between tussock tundra and dry heath.

Description: Recycling phosphorus (P) within the food system is fundamental to long-term sustainability. This greenhouse study compared three sources of recycled P – struvite precipitated from municipal wastewater, black soldier fly frass from food waste, and anaerobic digestate of food waste – to mono-ammonium phosphate (MAP), compost, and a control. Italian Ryegrass (Lolium multiflorum) was harvested four times during a 123 day trial from a P-depleted soil. In nitrogen (N) sufficient conditions, all amendments significantly increased cumulative ryegrass yields compared to the control, and were not significantly different from MAP. Relative P supply was frass=MAP〉struvite〉= compost〉=digestate〉〉control. The recycled nutrient sources tested show promise as sustainable P sources.

Description: Waves and tidal currents can interact to produce strong seabed shear stress and mobilization of sediments on continental shelves. Modelled wave and tidal current data for a 3-year period were used in a combined-flow sediment transport model to simulate the seabed shear stresses and the mobilization of uniform medium sand on the continental shelves of Canada. The modelling results are presented to establish the first national framework of seabed disturbance and sediment mobility on the continental shelves of Canada. Strong waves and tidal currents on the Canadian continental shelves produce mean bed shear velocity 〉5 cm·s−1. Medium sand can be mobilized 〉50% of the time over many areas on the shelves. The mobilization by tidal currents occurs over 36% and by waves over 50% of the shelf area, demonstrating that mobilization of sediments is dominated by waves on the Canadian continental shelves. Combined shear stresses due to wave and tidal current interaction further increase sediment mobilization to over 68% of the shelf area. The spatial variation of the relative importance of wave and tidal disturbances allows classification of the continental shelves into six disturbance types. Innovative Seabed Disturbance (SDI) and Sediment Mobility (SMI) indices are proposed to quantify the seabed exposure to oceanographic processes and sediment mobilization, incorporating both the magnitude and frequency of these processes. The proposed SDI and SMI, together with the disturbance type classification, can be used as standard parameters to best quantify seabed disturbance and sediment mobility on other shelves of the world.

Description: The bender element (BE) test has been widely used for the dynamic characterization of soil specimens at low-shear strain levels. However, the actual behavior of the BE inside a soil specimen remains unknown. Thus, the current ASTM standard does not consider the interference of compressional and shear waves in BE testing, which can lead to significant errors in the evaluation of shear wave velocities. The main objective of this paper is to present a numerical model of the BE system to better understand the response of the BEs inside a soil sample. The model is calibrated, verified, and then used to demonstrate the importance of taking into consideration the interaction between compressional and shear waves for the correct interpretation of BE measurements. The model successfully captured the measured vibrations of the BE in air as well as inside transparent soils. More importantly, the numerical simulations provide a new understating of the significant interactions of P-waves and S-waves especially in clay soils. Thus, the proposed coupled piezoelectric and solid mechanics model can be used to study the soil-BE interaction so that sound recommendations can be given to improve the interpretation of BE tests in different soils.

Description: Rolling Dynamic Compaction (RDC) is a soil compaction technique, which is capable of improving thick layers of soil at a relatively fast operating speed. The paper presents the results of laboratory experiments conducted on 1:13 scale models of the 4-sided, 8- and 12-tonne, Broons BH-1300 and BH-1300 HD impact rollers to study the performance of the scale model at four different operating speeds. A series of laboratory tests are undertaken using transparent soils and the particle image velocimetry (PIV) technique to investigate the effectiveness of the models. The transparent soil employed in this study consists of fused quartz and a pore fluid which matched the refractive index of the fused quartz. A one-particle thick layer of coloured fused quartz is embedded in the centre plane of the transparent soil to visualise soil internal displacements and a digital camera is used to capture the speckled pattern during the scale model testing process. The results show that the heavier module induces greater soil displacements at each operating speed. The optimal operating speed is approximately 299 mm/s for both module weights. The most significant soil displacements occur within the first 20 passes and, no obvious ground improvement is observed after 35 passes. The results of this study demonstrate the unique capability of transparent soil to study soil displacements induced by the ground improvement scale models.

Description: A series of automatic time-lapse cameras installed along the southwestern side of Tasiapik Valley, near the village of Umiujaq, Nunavik (Northern Québec) documented several departure modes and types of snow involved in snow avalanches during winter 2017-18. These included cornice-avalanche dynamics, slab and loose snow avalanches, and clean and dirty snow avalanches. At the top of the selected slope, a camera monitored the development of a snow cornice beginning in November 2017, detecting multiple cornice failures over the winter and spring. The track and deposition area of the runout paths were monitored from two cameras downslope, revealing the concomitance of snow-cornice fall and snow-avalanche triggering. Snow-avalanche activity remained relatively infrequent until the end of May 2018. Spring snow-avalanche activity is characterized by wet and dirty snow avalanches carrying debris to the foot of the slope and by runout zones located near the road along the slope.

Description: The age and nature of the Neoproterozoic – early Paleozoic rift–drift transition has been interpreted differently along the length of the North American Cordillera. The Ediacaran “upper” group (herein elevated to the Rackla Group) of the Coal Creek inlier, Yukon, Canada, represents a key succession to reconstruct the sedimentation history of northwestern Laurentia across the Precambrian–Cambrian boundary and elucidate the timing of active tectonism during the protracted breakup of the supercontinent Rodinia. These previously undifferentiated late Neoproterozoic – early Paleozoic map units in the Coal Creek inlier are herein formally defined as the Lone, Cliff Creek, Mount Ina, Last Chance, Shade, and Shell Creek formations. New sedimentological and stratigraphic data from these units is used to reconstruct the depositional setting. In the Last Chance Formation, chemostratigraphic observations indicate a ca. 5‰ δ13Ccarb gradient coincident with the globally recognized ca. 574–567 Ma Shuram carbon isotope excursion. Map and stratigraphic relationships in the overlying Shell Creek Formation provide evidence for latest Ediacaran – middle Cambrian tilting and rift-related sedimentation. This provides evidence for active extension through the Cambrian Miaolingian Series in northwestern Canada, supporting arguments for a multiphase and protracted breakup of Rodinia.

Description: Plant roots are known to provide mechanical reinforcement to soils upon shearing and seismic loading. However, the effects of different stress paths on root reinforce-ment are unclear. Moreover, whether, and how, roots provide resistance to soil lique-faction upon cyclic loading have rarely been studied. The objective of this study is to conduct a series of undrained triaxial tests to investigate the monotonic and cyclic behaviour of rooted sand. Roots of vetiver grass (Chrysopogon zizanioides L), which has been advocated for use in shallow slope stabilisation purposes, were used for testing. The root diameters ranged between 0.3 to 1.5 mm, while the root volume ra-tios were 0.23%, 0.45% and 0.67%. It was discovered that the root reinforcement ef-fect was anisotropic and path-dependent. Along the extension path when the major principal stress was perpendicular to the predominant root orientation, the root-induced increase in soil friction angle was approximately 10o. This increase was much greater than the case along the compression path where the change was min-imal. The presence of roots prevented the limited flow failure (which occurred in the unreinforced sand), and the failure mode of root-reinforced soil switched to cyclic mobility. The liquefaction resistance was improved with an increase in root volume, and this improvement was more remarkable at higher cyclic stress ratios.

Description: When using initial deformation from oedometer tests to quantify sample disturbance, a correction for false deformation is sometimes needed. A method to determine this false deformation is presented.

Description: Alpine and arctic bryophytes have been found to respond negatively to climate change, but since they are often analysed as one functional group, there is limited knowledge on species-specific responses. In this study, we examine how nearly two decades of experimental warming by open top chambers (OTC) and ambient warming have affected the bryophyte community structure in an alpine Dryas octopetala heath in Finse, southwest Norway. In contrast to what we expected, we found that bryophyte abundance, species richness and evenness increased over time in the control plots, indicating a positive response to ambient warming. However, the increase in bryophyte abundance and cover was suppressed in experimentally warmed plots compared to control plots. Bryophyte community composition changed in a similar direction in response to both ambient and experimental warming. Acrocarpous mosses were not affected stronger by warming than pleurocarpous mosses, but individual species and taxa showed contrasting responses. Our study highlights the importance of studying bryophyte responses to environmental change, as well as combining long-term observations with experimental warming.

Description: A plough pan with reduced permeability always accumulates infiltrated water along slopes then saturates the cultivated layer under continuous rain. Topsoil saturation is a frequent phenomenon and an important process of the special soil slopes. A methodology and device system was used in this study to keep cultivated purple soil saturated. Strands of scouring tests were developed to quantify the rill erosion and sediment transport processes along a saturated purple soil slope at four experiment slopes (5°, 10°, 15°, and 20°) and three flow discharges (2, 4 and 8 L min−1). The experimental results indicated that the sediment transport capacity on a saturated purple soil slope ranged from 0.03 to 1.56 kg s−1 m−1 with the increasing trend along the slope gradient and flow discharge, and the increasing trend could be well matched by a nonlinear multivariable equation. The sediment concentration of the saturated purple soil slope exponentially increased with rill length and decreased with the increment rate and the maximum sediment concentrations observed in this study in different hydraulic events ranged from 108.13 to 1174.20 kg m-3. Saturated and non-saturated purple soil slopes erode differently with the maximum sediment concentration of saturated purple soil slope recorded at approximately 1.42-2.10 times the values for non-saturated purple soil slope. The findings of this research help illustrate the sediment transportation and erosion behaviors of a saturated purple soil slope, and serve as the basis for determining the parameters in the erosion models of the purple soil slope.

Description: Constant head tests are commonly used for field measurements of fracture transmissivity. As a bulk transmissivity is measured for each test section, it is frequently unclear how this transmissivity relates to the hydraulic properties of individual fractures. The goal of this study is to determine if constant head tests conducted at scales larger than the average fracture spacing can be used to generate discrete fracture network (DFN) models that describe transport. The methodology involved generating DFNs using measurements from constant head tests conducted at lengths both above and below the average fracture spacing at a site in Ontario, Canada. Transport predictions from DFNs produced from different scales of hydraulic tests were compared to determine if a method for proportioning larger-scale test results to obtain a DFN representative of the smaller-scale tests could be established. The results of this study indicate that the choice of method used to apportion bulk transmissivities has a significant impact on transport simulations, with a difference in mass arrival of over a factor of two at travel distances less than 50 m. While the most appropriate method is case specific, the error resulting from the choice needs to be considered when using DFN models.

Description: Crops in the northwest arid region of China frequently suffer from low emergence and poor yield due to high water deficit. Mulching is an important approach to reduce irrigation amount while increasing productivity but faces challenge of ecological adaptability in this region. A field experiment was carried out in the three growing seasons from 2011 to 2013 to study effects of mulching with crushed wheat straw padding and plastic film on sunflower seed emergence and yields under different irrigation intensities. A two factor (mulching, irrigation intensity) completely randomized block design was applied, resulting in a total of 12 treatments repeated three times. Mulching treatments includes: zero mulch (N), straw mulching at the beginning of trial (S), plastic film mulching when sowing (F), a commonly used mulching by local farmers, and double mulching with plastic film on the crushed wheat straw layer (SF). Irrigation intensity includes: High (H=900 m3 ha-1), Medium (M=750m3 ha-1), Low (L=600m3 ha-1). Results showed that all mulching treatments promoted early emergence of seedlings compared with N, with SF and F performing the better than the rest. SF was the best-performing mulching approach in this study, and had significantly improved sunflower yield and yield components compared with other treatments. In SF, medium irrigation level had significantly increased sunflower 100-seed weight. Therefore, SF with medium irrigation level showed the most positive effect on sunflower production and in now the recommended agronomic solution for sunflower production in the northwest arid regions and potentially, other irrigated areas with similar ecological conditions.

Description: Pipelines in the offshore sector make common use of polypropylene (and other polymer) coating systems to protect the infrastructure and provide thermal insulation. High Pressure High Temperature (HPHT) pipelines are subject to large axial loads due to restraint by seafloor soils of thermal strains in the pipe wall. Friction between pipe coating material and seafloor soil plays a defining role in the build-up of axial stress and the formation of lateral buckling. Accurate quantification of pipe-soil interface friction is key to robust pipeline stability design and possibilities to enhance or manipulate the friction coefficient may be attractive to designers. An extensive campaign of soil and interface tests using a range of granular materials and polypropylene surface specimens engineered to achieve varying surface textures was carried out. The results show that interface friction primarily depends on stress level and the magnitude of the surface texture in relation to the particle size. Herein, a new relative textural parameter, Ta, is developed that, unlike alternative relative roughness parameters, can be obtained using conventional profilometry measurement techniques. An expression for estimating the friction factor in relation to texture and stress level is proposed which can serve as a useful predictor of pipe-soil interface friction.

Description: The immersion weakening effect of natural soil has always been a difficult problem encountered in geotechnical engineering practice. The bond dissolution is a common cause of soil strength deterioration, which remains not well understood yet. In this study, a thermodynamic-based constitutive model of structural soils based on the α model is first established, considering the bond strength by modifying the yield surface size and gradually reducing the bond strength with the development of plastic strain. Furthermore, by taking the meso-mechanisms of bond dissolution into account, the evolution rule of the free energy during the bond dissolution process is derived based on a homogenization approach, and a thermodynamic-based constitutive model of structural soil with bond dissolution is thereafter developed. By comparing with the results of one-dimensional compression tests and conventional triaxial tests, the model is verified to be capable of reflecting the gradual destructuration process of soil while loading. The comparison with triaxial test results of completely decomposed granite after different immersion durations and parametric studies show that based on the cross-scale energy equivalence, the model can well reflect the strength deterioration characteristics of completely decomposed granite with bond dissolution mechanisms at the mesoscale fully considered.

Description: Dear Author: Please reduce the abstract length down below 250 words both in the manuscript text file and pasted here.

Description: The mid-Cretaceous Peninsular Ranges orogeny occurred in the North American Cordillera and affected rocks from Mexico to Alaska. It formed when a marine trough, open for ~35 Myr, closed by westerly subduction beneath a 140-100 Ma arc complex. In Part I we described the features of the orogen in Mexico and California, west to east: back-arc trough, magmatic arc, 140-100 Ma seaway, post-collisional 99-84 Ma granodioritic-tonalitic plutons emplaced into the orogenic hinterland during exhumation, an east-vergent thrust belt, and farther east, a flexural foredeep. In western Nevada, where the Luning–Fencemaker thrust might be a mid-Cretaceous feature, arc and post-collisional plutons occur in proximity. The orogen continues through the Helena salient and Washington Cascades. In British Columbia, rocks of the 130-100 Ma Gambier arc lie west of the exhumed orogenic hinterland and 99-84 Ma post-collisional plutons to collectively indicate westerly subduction. East-dipping reverse faults near Harrison Lake, active from ~100 Ma until ~90 Ma, shed 99-84 Ma debris westward into the Nanaimo back-arc region. Within Insular Alaska, the Early Cretaceous Gravina basinal arc assemblage was deformed at 100 Ma, and flanked to the east by a high-grade hinterland cut by post-collisional plutons. In mainland Alaska, the 100 Ma collision of Wrangellia and the Yukon-Tanana-Farewell composite terrane occurred above a southward-dipping subduction zone as shown by the 130-100 Ma Chisana arc sitting on Wrangellia and southward-dipping, northerly vergent thrusts in the Lower Cretaceous Kahiltna basin to the north. The outboard back-arc region was filled with post-collisional detritus of the McHugh complex.

Description: Indigenous people possess information of animals’ habitat use and behaviour; information essential for management and conservation of species affected by climate change. Accessibility of species that are important to Indigenous hunters may also change with environmental conditions. We documented Indigenous Knowledge of bearded (ugruk in Iñupiaq), ringed (natchiq), and spotted seals (qasigiaq) in Utqiaġvik, Alaska, using semi-directed interviews with Iñupiaq hunters. This study originated from discussions with an agency of the regional municipal government to serve co-management efforts and understand habitat use of species subjected to climate change. Results indicated that ringed seals are associated with higher ice concentrations in winter than bearded seals and changes in sea ice retreat in spring may have greater impact on ringed seal habitat use because they are more likely to haul out on ice in spring. Additionally, all three species have foraging hotspots, used over several days by multiple individuals. Bearded seals, and to a lesser extent spotted and ringed seals, will use currents to forage. Results also revealed the use of inland water bodies and terrestrial habitat, which may become more important for bearded and ringed seals with changing ice concentrations and should be considered in management and conservation of these species.

Description: In this paper, two artificial intelligent models (i.e., artificial neural networks (ANN) and multivariate adaptive regression splines (MARS)) were developed using cumulative percentiles from grain-size distribution (GSD) curve as input information to predict the soil-water characteristic curve (SWCC). The importance of each input variable was testified using two different sensitivity analyses. The results show a strong correlation between the SWCC and GSD curves based on large volume of datasets. The ANN provides higher accuracy due to its unique structure; however, MARS model facilitates in developing a regression equation that contributes to stable performance. The SWCC can be reliably predicted with MARS regression equation using one data point from the GSD curve and bulk density information. Sensitivity analysis suggests that the prediction of the SWCC is also possible with a reasonable degree of accuracy by using single data point information from the GSD curve as an input variable. Finally, a novel AI aid design method is proposed by combining MARS regression equation along with physico-empirical model and fitting equation that provides a rapid and reliable technique for predicting the SWCC of sands.

Description: Climate change is rapidly warming high latitude and high elevation regions influencing plant community composition. Changes in vegetation composition have motivated the coordination of ecological monitoring networks across the Arctic, including the International Tundra Experiment (ITEX). We have established a long-term passive warming experiment using open-top chambers, which includes five distinct plant communities (Dry Heath; Tussock Tundra; and Dry, Mesic, and Wet Meadow). We have measured changes in plant community composition based on relative abundance differences over 26 years. In addition, relative abundance changes in response to fertilization and warming treatments were analysed based on a 7-year Community-Level Interaction Program (CLIP) experiment. The communities had distinct soil moisture conditions, leading to community specific responses of the plant growth forms (deciduous shrubs, evergreen shrubs, forbs and graminoids). Warming significantly affected growth forms, but the direction of the response was not consistent across the communities. Evidence of shrub expansion was found in nearly all communities, with soil moisture determining whether it was driven by deciduous or evergreen shrubs. Graminoids increased in relative abundance in the Dry Meadow due to warming. Growth form responses to warming are likely mediated by edaphic characteristics of the communities and their interactions with climate.

Description: Vegetation change of the Arctic tundra due to global warming is a well-known process, but the implication for the belowground microbial communities, key in nutrient cycling and decomposition, is poorly understood. We characterized the fungal and bacterial abundances in litter and soil layers across 16 warming experimental sites at 12 circumpolar locations. We investigated the relationship between microbial abundances and nitrogen (N) and carbon (C) isotopic signatures, indicating shifts in microbial processes with warming. Microbial abundances were 2-3 orders of magnitudes larger in litter than in soil. Local, site-dependent responses of microbial abundances were variable, and no general effect of warming was detected. The only generalizable trend across sites was a dependence between the warming response-ratios and C:N ratio in controls, highlighting a legacy of the vegetation on the microbial response to warming. We detected a positive effect of warming on the litter mass and δ15N, which was linked to bacterial abundance under warmed conditions. This effect was stronger in experimental sites dominated by deciduous shrubs, suggesting an altered bacterial N-cycling with increased temperatures, mediated by the vegetation, and with possible consequences on ecosystem feedbacks to climate change.

Description: An increase in the operation speed of high-speed trains often leads to an increase in the loading frequency on subgrade soil. Hence, the long-term dynamic behavior of the subgrade and the service performance of high-speed tracks are affected. To determine the stress-strain characteristics of granular soil under high-frequency loading, a triaxial test setup was modified to investigate the effects of loading acceleration and duration, water content, vibration frequency, cell pressure, and initial soil density. The experimental results indicate that there are reductions in axial stress and volumetric strain during high-frequency loading. The reduction in axial stress is as high as 40%, and that of volumetric strain, which is permanent, could approach 0.1%. The stress reduction, strain compression, and excess pore pressure are found to vary linearly with vibration acceleration when a/g〉0.02. The reduction in strength and strains are found to depend on the loading acceleration and effective cell pressure, but independent of the loading duration, water content, frequency, and initial density. A threshold acceleration a=0.02g is observed, below which the changes in the shear strength and volumetric strain induced by vibration are negligible. At high vibration acceleration, the strain amplitude could increase, eventually leading to a collapse of the specimen.

Description: Repeated applications of liquid dairy manure (LDM) and perennial crops generally favor nitrogen (N) stocks in soils, but in ways that may differ with soil type and other management practices. The objective of this study was to assess the long-term (21 yr) changes in soil N stocks (0–50 cm) of a silty clay soil, in a cool humid climate, in response to mineral fertilization (MIN) or LDM, combined with two tillage practices [chisel plow (CP), or moldboard plow (MP)], and two crop rotations [cereal monoculture (monoculture) or cereal–perennial forage rotation (forage-based rotation)]. The forage-based rotation favoured a greater accumulation of N in the first 20 cm of soil (+50 kg N·ha−1·yr−1) when compared with the monoculture. Tillage practices did not impact N stocks in the whole soil profile, but influenced its vertical distribution, with greater accumulation at the surface with CP, and at depth with MP. Annual input of LDM increased N stocks at the surface (0–20 cm) compared with MIN, especially when combined with the forage-based rotation. After 21 yr, soil N stocks (0–50 cm) with LDM were 32% (+2 t N·ha−1) higher in the forage-based rotation than in the monoculture, suggesting better retention and more efficient use of manure-N with perennial forages than cereals. Comparisons between the N mass balance computed for each cropping system, and the changes in soil N stocks indicated that accumulation of N under the forage-based rotation was largely due to symbiotic fixation by legumes in the forage mixture.

Description: We analyzed Arctic Char stable isotope ratios and fatty acid composition from two geographically proximal Nunavut lakes, Qasigiyat and Iqalugaarjuit, to determine if anadromous and resident Arctic char occupied different trophic niches. Resident Arctic char had lower δ13C and δ34S, indicative of a freshwater feeding, compared to anadromous individuals. Significantly lower δ15N of residents suggests the ecotypes feed at different trophic levels. Significantly wider δ13C and δ15N ranges in residents implied a broader trophic niche or a wider range in baseline prey isotope values. Results also provide further evidence for resident use of the estuarine environment in Qasigiyat. Immature Arctic char occupy a different trophic niche than both resident and anadromous fish within Iqalugaarjuit, but this relationship is less clear in Qasigiyat. Distinct stable isotope and fatty acid profiles indicate that resident and anadromous Arctic char have distinct trophic niches, marine for anadromous, freshwater for resident. Immature Arctic char seem to occupy a distinct niche from both anadromous and resident fish, which likely relates to use of both freshwater and estuarine environments, depending on developmental stage. We show the first evidence of the fatty acid differences and niche segregation between sympatric anadromous and resident ecotypes in Arctic Char.

Description: Satellite remote sensing is a popular approach for identifying vegetation change in northern environments; however, disentangling ecological processes causing variability in spectral indices remains a challenge. Here, we aim to determine how shrub characteristics differ between low and rapidly greening areas near Nain, Nunatsiavut, Canada. Using a cross-scale approach, we combined remotely sensed spectral greening trends (Normalized Difference Vegetation Index; Landsat Collection 1; 1985-2018) with shrub dynamics derived from ring-widths of green alder (Alnus alnobetula) and dwarf birch (Betula glandulosa). Differentiation of spectral greening classes appears to be driven by the distribution of shrub species. Alder were taller, grew faster, had more recent stem initiation than dwarf birch, and were dominant in rapid greening subplots. In low greening subplots, alders were co-dominant with dwarf birch, whose dominant stems initiated more gradually, were shorter, and had lower rates of vertical growth. The radial growth of both shrub species was favoured by warm winter temperatures and precipitation, whereas rapid greening alder was also favoured by warm summer temperatures. Further shrub growth will likely be enhanced under continued climate warming if moisture does not become limiting. This research demonstrates the importance of species identity in determining rates of spectral greening in northern environments.

Description: The Avalon Peninsula, Newfoundland, Canada, defined as the type zone of Avalonia is believed to have been impacted by several orogenetic and deformation events since the Neoproterozoic. Previous studies determined the lowest degree of metamorphism reached in the successions was of the prehnite-pumpellyite or greenschist facies. We sampled and measured thirteen clastic sedimentary sections ranging from the late Ediacaran to the Early Ordovician and analysed the illite “crystallinity” of 331 samples using the Kübler index. Our results show diagenetic zones occur related to lithology, age and burial depth, respectively, and regional setting. Samples adjacent to the fault zones bounding the Holyrood Horst experienced among the highest degree of metamorphism (anchizone) in the study area. The lowest degree of thermal alteration occurs in the high stratigraphic sections at the centre of the horst structure where shallow diagenetic conditions are preserved. Fault zones, most probably active during the Acadian Orogeny, may have served as potential paths for hot fluids in bounding areas of the horst, whereas the centre of the horst remained almost unaffected by any metamorphic overprint. The thermal impact decreases from the Bonavista Peninsula to the study area from greenschist facies to anchizonal and diagenetic. The study area experienced lower metamorphic conditions than major regions of Avalonia south of the study area on the mainland of New Brunswick and Maine and eastwards in Europe. The thermal impact is in part consistent with a few other areas of Avalonia, such as the Mira terrane and the Antigonish Highlands in Nova Scotia.

Description: The lake ecology of high-latitude fishes is strongly influenced by seasonal feeding opportunities and environmental stochasticity in Arctic environments. Arctic Charr (Salvelinus alpinus) populations are prevalent throughout the Arctic and show multiple life history strategies across their range. Unlike Old World populations the lake ecology of Arctic Charr populations on south Baffin Island remain poorly defined. We examined the comparative seasonal lake ecology of two differing Arctic Charr populations (anadromous and landlocked) in Cumberland Sound, Nunavut. Anadromous charr showed no evidence of feeding occurring within freshwater once they began seaward migrations. Anadromous charr achieve sexual maturation at a larger size and younger age than landlocked charr. Landlocked charr used more lake habitats than anadromous charr with feeding opportunities as an apparent influence on habitat selection. Landlocked charr fed year round. They adopted a cannibalistic feeding strategy in the winter but consumed a variety of prey items in the fall. Littoral habitat was found to be important to all sizes of charr in both seasons. Smaller anadromous charr (

Description: Historically, fisheries have been monitored at the individual stock level, without consideration to connectivity to other species or activities in the ecosystem. The ecosystem approach requires that the stock and fishery be seen in the context of predators, competitors, prey, by-catch impacts, other fisheries and abiotic environmental variables so that management is holistic. In this review, we describe the components of the ecosystem approach applied in the scientific investigation of fisheries in Cumberland Sound, NU. Relative to other Canadian Arctic locales with commercial fisheries operations, the Cumberland Sound area has a greater biodiversity and abundance of fish and marine mammal species These components support active fisheries for Arctic Charr, Greenland Halibut, Beluga Whale as well as Ringed, Bearded and Harp Seal. The species and their fisheries are variable in character, their ecosystem effects and their response to the environment. We describe the species dynamics and their fisheries within an ecosystem context. We briefly note the challenges to developing an overarching model of the system such as the integration of the different life histories of the species, as well as the incorporation of future non-fisheries related disturbances.

Description: The soil arching mechanism is partly responsible for the transfer of stresses away from the soft subsoil and towards the relatively stiff column heads in column supported embankments. Experimental studies have shown that the load transfer resulting from soil arching evolves progressively with increasing subsoil settlement. Past numerical studies exploring soil arching in column supported embankments have typically not been able to capture this progressive development of load transfer. A series of improvements on past numerical studies are outlined which allow for improved simulation of the soil arching mechanism in column supported embankments. These improvements include implementation of a strain-softening constitutive model, non-local integral type regularisation and the application of the Arbitrary Lagrangian-Eulerian finite element method. The benefits of these improvements are observed through comparison of simulation results to recent experimental studies of column supported embankments. The comparison indicates that these techniques allow key aspects of soil arching kinematics and mechanics to be captured.

Description: In a scenario of world population increase and climate change, an efficient use of water is key for agricultural production. Onion is one of the most profitable crops and can adapt to particular conditions of water stress. The objective of this research was to determine growing degree-days (GDD) and accumulated radiation under non-stress conditions, and yield of an F1 2000 hybrid of onion (Allium cepa L.) under water deficit and biofertilization in a semi-arid environment. An established nutrient requirement of 247 kg N, 240 kg P2O5 (105 kg P), 240 kg K2O (199 kg K) and two irrigation factors were applied: normal irrigation (NI) with a daily and water deficit (WD) with a three-day interval irrigation frequencies. The effect of biofertilization was evaluated through the inoculation of a microbial consortium in combination with four NPK fertilizer treatments. The crop accumulated 1334 °Cd and 1188 MJ m-2 d-1 at the time of harvest at 71 days after transplanting (DAT). The yield was 36 t ha-1, similar under both irrigation conditions; and the WD treatment resulted in a 35% water savings, a 47% and 65% increase in water use efficiency (WUE) and modulus of elasticity, respectively. The microbial consortium resulted in a 50% NPK savings under non-limiting water conditions and produced a similar yield compared to the 100% NPK non-inoculated control. The lower irrigation frequency together with the 100% NPK fertilization dose without the microbial consortium, and the use of the microorganisms and the 50% NPK treatment without water stress are recommended as agrosustainable practices for onion production.

Description: Appropriate application of corn straw residues increase soil organic carbon (SOC) sequestration. Yet, sequestration and stabilization of added carbon (C) during corn straw transformation is not fully understood. Here, we present changes in soil humus C and humic acid (HA) molecular structure during corn straw decomposition in an incubation experiment carried out for 270 days at 25 °C. Corn straw was applied at the amount of 74.76 g per 18 kg soil (i.e., 1.57 g C kg-1), in the soil surface (CS1), incorporated within 0–10 cm (CS2), applied below 10 cm soil depth (CS3), and no corn straw applied. The results showed that after corn straw application (CS1, CS2 and CS3), accumulation of SOC content was rapid in the first 90 days. The HA spectral results of straw amended soils showed a slight increase in aliphatic C compounds and amino acids in day 90. In day 180, the degree of condensation was less, and aliphatic C compounds were present in large quantities in soil HA. As decomposition advanced to day 270, the aliphatic character of HA appeared to slightly weaken, and soil HA was enriched with aromatic structures. These results suggest that corn straw application enrich soil HA with more aliphatic C compounds in the early stages of decomposition, and aromatic C structures are formed in the later stage of decomposition. Incorporation of corn straw into the soil (CS2 treatment) is more conducive in increasing SOC and aliphaticity in HA during corn straw decomposition, which can potentially increase C sequestration.

Description: This study presents the use of controlled blasting as a source of seismic energy to obtain the coupled, dynamic, linear-elastic to nonlinear-inelastic response of a plastic silt deposit. Characterization of blast-induced ground motions indicate that the shear strain and corresponding residual excess pore pressures (EPPs) are associated with low frequency near- and far-field shear waves that are within the range of earthquake frequencies, whereas the effect of high frequency P-waves are negligible. Three blasting programs were used to develop the initial and pre-strained relationships between shear strain, EPP, and nonlinear shear modulus degradation. The initial threshold shear strain to initiate soil nonlinearity and to trigger generation of residual EPP ranging from 0.002 to 0.003% and 0.008 to 0.012%, respectively, where the latter corresponded to ~30% of Gmax. Following pre-straining and dissipation of EPPs within the silt deposit, the shear strain necessary to trigger residual excess pore pressure increased two-fold. Greater excess pore pressures were observed in-situ compared to that of intact direct simple shear (DSS) test specimens at a given shear strain amplitude. The reduction of in-situ undrained shear strength within the blast-induced EPP field measured using vane shear tests compared favorably with that of DSS test specimens.

Description: Arctic charr (Salvelinus alpinus) are phenotypically plastic with multiple dietary-morphological relationships observed throughout their circumpolar range. Feeding strategies often differ between Arctic charr life histories and can impact size-at-age and morphological attributes. We examined growth, condition, and body morphology for two high Arctic populations of Arctic charr with anadromous and landlocked life histories. Anadromous Arctic charr had higher growth rates, achieving mean lengths two times those of landlocked Arctic charr by age 10 and had higher overall condition, particularly in the fall. Ontogenetic shifts in diet were suspected in both populations, with an abrupt shift to marine feeding in the anadromous population and a gradual shift to piscivory in the landlocked population. Morphological differences between life histories manifested most predominantly in larger eye diameter, longer pectoral and pelvic fins, and longer upper jaws of landlocked Arctic charr, suggestive of piscivorous feeding specialization of landlocked fish 〉350mm. Our findings emphasize the benefits that marine feeding can have for growth and condition of freshwater fishes in Arctic environments and also convey the necessity of adaptive feeding strategies to optimize growth and condition in fishes inhabiting low-production lacustrine habitats.

Description: Stomatal conductance (SC) and chlorophyll concentration (CC) are sensitive to soil matric suction (ψ). The relationship between these two plant parameters and ψ in root zone can help understand the water uptake efficiency and photosynthetic capacity of a plant. This paper aims to quantify the relationships between SC and CC with ψ, for Schefflera arboricola grown in compacted bare silty sand and biochar amended soil (BAS). Plant parameters (SC, CC, leaf area (LA), root length (RL)) and ψ were regularly monitored in an atmospheric controlled room. The maximum recorded SC was greater in BAS than that in bare soil due to the higher water demand of LA. Based on measured data upon evapotranspiration, two equations are proposed to interpret the effects of ψ on plant water uptake and photosynthesis. A fitting equation is established to relate normalized SC with ψ to identify a threshold suction (ψNSCt; indicator of drought stress resistance). The magnitude of ψNSCt is found to be mainly dependent on LA/RL ratio and root ends. Furthermore, a new relationship between CC and ψ is observed and developed. A decrease in CC at higher ψ is attributed to leaf senescence and stomatal closure, restricting plant to produce more chlorophyll.

Description: The Cumberland Sound (Nunavut, Canada) beluga whale (Delphinapterus leucas) population has been designated as threatened and updated biological information about summer distribution is required for a sound recovery plan. Variation in aerial survey counts are speculated to occur due to movement of belugas in and out of the fiord, and there is still uncertainty related to their distribution within key summer habitat. To address these knowledge gaps, non-invasive passive acoustic monitoring (PAM) systems were deployed in August of 2010 and 2011. An automated detector was used to determine presence/absence and quantify calls by recorder site. Results were verified by partial manual analysis of 20% of the files. The detector had a minimum accuracy of 85% for presence/absence and 42% for call quantification. Belugas were detected primarily at the uppermost site of Clearwater Fiord, with detections subsiding with increasing proximity to the fiord entrance. Diel variation in call patterns were quantified at two separate sites in different years, but no correlation was observed between tidal cycles and number of detections. This study indicates that Cumberland Sound beluga may prefer sites at the head of Clearwater Fiord. Further research is required to identify which environmental variables contribute to this observed summer distribution.

Description: Balancing nutrient inputs from manure and supplemental inorganic fertilizers with crop requirements should achieve crop yield goals and agro-environmental targets. We asked if composted dairy cattle manure, alone or in combination with inorganic fertilizers, could sustain the corn and soybean yields, without increasing the residual soil N and soil P saturation of a sandy-loam soil in southern Quebec, Canada. Cropping systems were continuous silage corn and corn-soybean rotation, with each phase of the rotation grown every year, for 5-yr. Cropping systems were amended with compost at rates of 0, 15, 30 and 45 Mg (wet weight) ha-1, and received supplemental inorganic fertilizer to supply 200 kg N ha-1 yr-1 to corn while assuring that corn and soybean received 45 kg P ha-1 yr-1 and 125 kg K ha-1 yr-1 from compost and inorganic fertilizer. Crop yields were similar in composted-amended and inorganically-fertilized plots. Corn yield was limited by N availability, and there was no P or K limitation in corn and soybean. Soil P saturation in the 0–15 cm layer exceeded the agro-environmental limit of 13.1% P/Al for a sandy-loam soil in Quebec, indicating that the P input exceeded crop uptake. Residual soil N concentration was affected more by the crop than the fertilizer source, with greater residual soil N in plots with higher grain production. Crop-induced priming can explain how N fertilizer cycles through the soil microbial community and is gradually mineralized during the growing season, and why crop senescence may trigger residual soil N release after harvest.

Description: Climate change increases the risk of severe alterations to essential wildlife habitats. The Arctic fox (Vulpes lagopus) uses dens as shelters against cold temperatures and predators. These dens, needed for successful reproduction, are generally dug into the active layer on top of permafrost and reused across multiple generations. We assessed the vulnerability of Arctic fox dens to the increasing frequency of geohazards (thaw settlement, mass movements, thermal erosion) that is arising from climate change. On Bylot Island (Nunavut, Canada) we developed, and calculated from field observations, a qualitative vulnerability index to geohazards for Arctic fox dens. Of the 106 dens studied, 14% were classified as highly vulnerable while 17% and 69% had a moderate and low vulnerability. Vulnerability was not related to the probability of use for reproduction. While climate change will likely impact Arctic fox reproductive dens, such impact is not a major threat to foxes of Bylot Island. Our research provides first insights into the climate-related geohazards potentially affecting Arctic fox ecology in the next decades. The developed method is flexible and could be applied to other locations or other species that complete their life cycle in permafrost regions.

Description: Fifty-five new Nd isotope analyses are presented for plutonic orthogneisses from the Grimsthorpe domain in the marble-rich segment of the Grenvillian Central Metasedimentary Belt (CMB) to test the back-arc aulacogen model for its origin. Nd isotope analyses from the Weslemkoon batholith, Elzevir batholith, Lingham Lake complex and Canniff tonalite are used to probe the crustal formation age of their source rocks. Despite its concentric foliation, the Weslemkoon batholith displays a complex geochemical pattern consisting of several NE trending domains with older TDM ages, surrounded by juvenile crustal material. The new Nd isotope results, coupled with geochemistry for the Weslemkoon and Elzevir batholiths depict the fragmentation of a block of old crust that formed a screen between en echelon segments of a mid-Mesoproterozoic back-arc rift zone. The isotope boundaries identified within the Weslemkoon batholith delineate magma pulses sampling two distinct sources, interpreted as Laurentian basement and juvenile basaltic underplate. Underplating could be attributed to slab rollback under the pre-Grenvillian continental margin arc. The intensification of rift-related magmatism in the CMB is demonstrated by its bimodal petrological character. A modern analogue for the tectonic context of the CMB is the Gulf of California, where subduction-related magmatism has transitioned to rift-related magmatism. However, the Gulf of California exhibits more transcurrent motion than is evidenced by the geometry of the CMB rift. A geometrical analogue for the break-up of the Elzevir block between two rift segments is provided by the Danakil block of the Red Sea, which is currently undergoing similar tectonic fragmentation.

Description: A large dyke of quartz-tholeiitic gabbronorite has been mapped for 59 km in southern New Brunswick, Canada, between Lepreau River in the northeast and Indian Island in the southwest. Scattered outcrops occur along a positive aeromagnetic lineament, providing a dyke strike of N42°E overall (segments N30°E to N72°E), dips of 80° to 90°NNW, and widths of 4 to 30 m. A new 40Ar/39Ar plagioclase age of 201.67 ± 0.35 Ma for the Lepreau River Dyke is similar to dates for the massive North Mountain Basalt in the Fundy Basin to the east. The dyke is associated with the Ministers Island and Christmas Cove dykes, which are indistinguishable in chemistry, petrology, and probable age, and we regard them as segments of the same co-magmatic dyke system. In addition, their petrology is similar to that of the basalts of the adjacent Early Mesozoic Fundy and Grand Manan basins. We propose that the Lepreau River and associated dykes were sources for the regional basin basalts, which in turn are part of the Central Atlantic Magmatic Province (CAMP) that overlaps the Triassic-Jurassic boundary and associated mass extinction event.

Description: Biochar, a carbon-rich material produced by the pyrolysis of organic residues, is frequently used as a soil amendment to enhance soil fertility and improve soil properties in tropical climates. However, in temperate agriculture, the impact of biochar on soil and plant productivity remains uncertain. The objective of this review is to give an overview of the challenges and opportunities of using biochar as an amendment in temperate soils. Among the various challenges, the type of feedstock and the conditions during pyrolysis produces biochars with different chemical and physical properties, resulting in contrasting effects on soils and crops. Furthermore, biochar aging, biochar application rates and its co-application with mineral fertilizer and/or organic amendments add further complexity to our understanding of the soil-amendment-plant continuum. Although its benefits on crop yield are not yet well demonstrated under field studies, other agronomic benefits of biochar in temperate agriculture have been documented. In this review, we proposed a broader view of biochar as a temperate soil amendment, moving beyond our current focus on crop productivity, and instead target its capacity to improve soil properties. We explored biochar’s benefits in remediating low productive agricultural lands, and its environmental benefits through long-term carbon sequestration and reduced nutrient leaching while curtailing our reliance on fertilizer input. We also discussed the persistence of beneficial impacts of biochar in temperate field conditions. We concluded biochar displays great prospective to improve soil health and its productivity, enhance plant stress resilience, mitigate greenhouse gas emissions and restore degraded soils in temperate agriculture.

Description: The Weibull function is applied extensively in the life sciences and engineering but underused in agriculture. The function was consequently adapted to include parameters and metrics that increase its utility for characterizing agricultural processes. The parameters included initial and final dependent variables (Y0 and YF, respectively), initial independent variable (x0), a scale constant (k), and a shape constant (c). The primary metrics included mode, integral average, domain, skewness, and kurtosis. Nested within the Weibull function are the Mitscherlich and Rayleigh functions where c is fixed at 1 and 2, respectively. At least one of the three models provided an excellent fit to six example agricultural datasets, as evidenced by large adjusted coefficient of determination (RA2 ≥ 0.9266), small normalized mean bias error (MBEN ≤ 1.49%), and small normalized standard error of regression (SERN ≤ 8.08%). The Mitscherlich function provided the most probable (PX) representation of corn (Zea mays L.) yield (PM = 87.2%); Rayleigh was most probable for soil organic carbon depth profile (PR = 96.4%); and Weibull was most probable for corn seedling emergence (PW = 100%), nitrous oxide emissions (PW = 100%), nitrogen mineralization (PW = 58.4%), and soil water desorption (PW = 100%). The Weibull fit to the desorption data was also equivalent to those of the well-established van Genuchten and Groenevelt–Grant desorption models. It was concluded that the adapted Weibull function has good potential for widespread and informative application to agricultural data and processes.

Description: Chronosequence studies of soil formation and ecosystem development provide important insights into the pathways and rates of change occurring on centennial and millennial time scales. In cool or temperate humid environments, Podzols are the predominant soil type formed under coniferous forests in coarse-textured parent material and have been a major focus of chronosequence studies. This study examined the rate and mechanisms of Podzol development and related forest productivity in a sand dune chronosequence in a hypermaritime climate in coastal British Columbia (BC). The sequence spans 10 760 ± 864 yr over eight sites and is the first documented chronosequence in coastal BC to span most of the Holocene Epoch. Soil samples from each genetic horizon were analyzed for bulk density, pH and concentrations of total carbon (C), pyrophosphate- and oxalate-extractable aluminum (Al) and iron (Fe), and total elements. Within ∼3500 yr, a mature Podzol had formed, with cemented horizons (ortstein and placic) present. Organo-metallic complexation appeared to be the dominant mechanism involved in podzolization. Despite a mild, moist climate conducive to chemical weathering, all soils had similarly low values for the chemical index of alteration, suggesting that congruent dissolution of primary minerals may be occurring. Ecosystem retrogression is apparent in the latter stages of the chronosequence — a phenomenon not previously documented in coastal BC. Further research is needed to examine the interactions of nutrient limitation, soil physical barriers, and other possible drivers of ecosystem retrogression.

Description: This paper presents the result of five pressuremeter tests conducted in deep three clay shale formations at a thermal operation site. Pressuremeter loading was imposed parallel to the bedding plane under an approximately undrained condition. Test data are analyzed using the axisymmetric cavity expansion theory. In parallel with triaxial test results, the analyses reveal several constitutive characteristics of the Westgate clay shale, in particular, the limited nonlinearity and the stress−strain-path dependency of shear modulus. A procedure is proposed to correct the data including multi-azimuth radial displacement measurements in the caliper plane and the anisotropic response of the borehole is studied. Two aspects of azimuthal anisotropy are assessed — (i) in-plane anisotropy of borehole stiffness and (ii) the anisotropy in expansion after borehole plastic yielding. The latter provides the implication of anisotropic in situ horizontal stresses, demonstrated by both experimental and numerical evidence. The influence of the radial and azimuthal variations of the elastic stiffness around borehole on the interpreted orientation of in situ horizontal stresses is discussed. An agreement is shown between the interpreted azimuth of major or minor in situ horizontal stress and the reported crustal stress orientation for the test least affected by such stiffness variation.

Description: Successful geotechnical projects occur when the design is based on a thorough understanding of the geologic and environmental systems and the interaction of these systems over time. The ability to examine and track movement through space and time has been an essential part of the geoprofessional’s toolkit since the onset of the practice. Since the early 2000s, high-resolution three-dimensional (3D) topographic data have begun to transform how we map and understand movement through time across spatially extensive regions at unprecedented levels of accuracy and confidence. This paper examines how high-resolution 3D topographical data, four-dimensional (4D) analysis, and visualization of data in 3D environments can improve our ability to better understand changes in the morphology and material behaviour through time, leading to better decisions and better outcomes. Evolution of advancements made over the past 20 years is presented through case studies where positive impacts were realized through the adoption of 3D remote sensing and 4D analysis, and cases where data could be used in the future to improve outcomes. The paper presents current research being done to further improve processing techniques and exploit new data collection and computational processing capabilities, pushing the capability of time-dependant 4D geotechnical monitoring to new limits.

Description: Conventional geotechnical soil classifications aim to classify soils into families with geotechnical characteristics and therefore similar behaviour; however, they require core samples and laboratory identification testing. Several empirical systems for estimating the nature of the soils have been developed on the basis of several in situ geotechnical tests. However, at present these systems remain empirical and they are often only used on an indicative basis. The objective of this article is, based on the analysis of dynamic penetrometric signals, to develop a methodology able to provide an estimate of the nature of the soil crossed. The methodology developed provide an automatic classification based on artificial neuron networks (ANNs) tools. Two types of ANN architectures were considered: multi-layer feedforward perceptron (MFP) and probabilistic neural network (PNN). The learning of these two tools was achieved through a base carried out in the laboratory and in situ. Both classification models were then tested in blind conditions and showed a good efficiency for calibrated soils and promising results for in situ soils.