Sand Depth Research Articles

Human walking biomechanics on sand substrates of varying foot sinking depth.

Our current understanding of human gait is mostly based on studies using hard, level surfaces in a laboratory environment. However, humans navigate a wide range of different substrates every day, which incur varied demands on stability and efficiency. Several studies have shown that when walking on natural compliant substrates there is an increase in energy expenditure. However, these studies report variable changes to other aspects of gait such as muscle activity. Discrepancies between studies exist even within substrate types (e.g. sand), which suggests that relatively 'fine-scale' differences in substrate properties exert quantifiable influences on gait mechanics. In this study, we compared human walking mechanics on a range of sand substrates that vary in overall foot sinking depth. We demonstrated that variation in the overall sinking depth in sand was associated with statistically significant changes in joint angles and spatiotemporal variables in human walking but exerted relatively little influence on pendular energy recovery and muscle activations. Significant correlated changes between gait metrics were frequently recovered, suggesting a degree of coupled or mechanistic interaction in their variation within and across substrates. However, only walking speed (and its associated spatiotemporal variables) correlated frequently with absolute foot sinkage depth within individual sand substrates, but not across them. This suggests that a causative relationship between walking speed and foot sinkage depth within individual sand substates is not coupled with systematic changes in joint kinematics and muscle activity in the same way as is observed across sand substrates.

Experimental Study of Erosion Prevention Model by Bio-Cement Sand

Microbially induced carbonate precipitation (MICP) technology is employed to reinforce the surface soil of a dam, aiming to prevent erosion caused by water flow and damage to the dam slope. The relationship between penetration depth, calcium carbonate content, and bonding depth was investigated at eight measuring points on the sand slope surface of a mold under different reinforcement durations. It was observed that as grouting reinforcement times increased, there was a gradual increase in calcium carbonate content but a rapid rise in penetration resistance. Moreover, the bonding depth of sand on the bio-reinforced sand slope increased with higher levels of calcium carbonate content. Microbial grouting reinforcement enhanced soil particle bonding force, requiring water flow to overcome this force for activation of sand particles. Consequently, microbial grouting reinforcement significantly improved shear strength and critical starting flow velocity on sand slope surfaces. The experimental results demonstrated that after MICP surface treatment through spraying, a dense and water-stable hard shell layer composed of bonded calcium carbonate and soil particles formed continuously on sample surfaces, effectively enhancing the strength and erosion resistance of sandy soils. These findings provide reliable evidence for silt slope reinforcement and dam erosion prevention.

Distribution of microplastics on sandy beaches in western and southern Japan and their fate in the oceans

The Japanese archipelago is surrounded by the Sea of Japan, the Sea of Okhotsk, the Pacific Ocean, and the East China Sea. The oceans are known to be contaminated by waste artifacts (marine litter). To investigate how these artifacts contaminate sandy beaches in Japan and their fate in the oceans, we sampled sand from 19 sandy beaches ranging from the western area of the main island of Japan (Honshu), which faces the Sea of Japan, to the westernmost island in the Japanese archipelago (Yonaguni Island), which faces the East China Sea. Almost all beaches were contaminated by marine litter. The maximum density by number of pieces was 604,600 per m3 in a 2-cm depth of sand on Yonaguni Island. Polystyrene foam was the most common artifact, and plastic fragments were second. The densities of artifacts by number and weight, and the type of artifacts, varied by location. A statistically significant positive relationship between the weights of artifacts and natural objects was observed, suggesting that they experience similar fates in the oceans. The major axis of the polystyrene foam in the Yonaguni area differed significantly from those in the Shimane, Tsushima, and Okinawa areas. The major axis in the Tsushima area significantly differed from those in all other studied areas. This study found the geological difference in the distribution and the major axis of polystyrene foams. These differences may be relevant to environmental physical factors (wind, rain, and waves), chemical alterations by ultraviolet rays, exposed time, the gyre, and local currents.

Sand Production Prediction and Management Using a One-Dimensional Geomechanical Model: A Case Study in NahrUmr Formation, Subba Oil Field

Sand production in sandstone reservoirs is a complex problem for oil and gas companies. This problem can damage downhole equipment and surface production facilities. This paper presents a sand production case and quantifies sand risks for the NahrUmr formation located in Subbaoilfied.The risk of sanding or rock failure is commonly observed during production phases as well as drilling operations. A (1D) mechanical earth model was created using wireline log data and core data for estimating the formations mechanical properties.The extrapolation method is utilized for vertical stress prediction, whereas pore pressure and static Young’s modulus were calculated using Slowness Eaton method and John Fuller correlation respectively. The poro-elastic model was used to determine horizontal principal stresses and hydrocarbon intervals susceptible to sand production issues.The purpose of this study was achieved using Tech-Log software. Sand onset intervals are firstly predicted as an open hole using ten methods: Loading factor (LF), Critical drawdown pressure (CDDP), B-index, schlumberger (Sc), Elastic combination index (Ec-index), Interval Transit-Time (DTc), Total porosity method (PHIT), unconfined compressive strength (UCS), Shear modulus to bulk compressibility ratio (G/Cb), and shear failure method. Approximately ten methods refer to the same intervals that can produce sand. Secondly, sand depths were predicted by representing the well according to what actually existed as a cased hole by calculating the critical drawdown pressure (CDDP), which is calculated at various depletion rates (0%, 15%, 25%, and 35%) in order to measure the effect of reservoir pressure depletion on sand production. The results show that as the rock strength is increased, the amount of sand-free drawdown and depletion becomes larger. Also, a single-depth analysis was conducted for problem intervals, indicatg a sandwillproducefromdepth of 2527.7 m under certain conditions. Therefore, it is necessary to install sand control equipment in this well.

Predicting lateral displacement of sand for mat foundation under simplified seismic loading

This research presents the settlement factor of sand for the lateral seismic excitation considering various peak ground accelerations. For this reason, analytical formulations are proposed to calculate the settlement factor. A one-dimensional model is considered to derive these formulations, which is the simplified form of the three-dimensional model. The seismic excitation is simplified by considering only peak ground acceleration (PGA) for the development of formulations. The proposed formulations are verified by the previous numerical studies. Also, a parametric study is conducted to consider the variable parameters such as super-structure loads, mat thickness, PGA factors, and depths of sand. According to the verification results, the observed and calculated sand settlement factor variation rates are slightly higher because of the considerations for the development of the proposed model. The maximum value of the sand settlement factor is found to be 434 for the PGA factor of 0.36 at the highest depth of the sand layer. Also, the sand settlement factor is gradually increased with the increment of the depth for all cases due to the increment of the stiffness. The lateral sand settlement factor is varied within a range of (60 ~ 434) considering all PGAs of the lateral seismic excitation.

Analysis of influencing factors of penetration mechanism and vertical bearing characteristics of monopile in calcareous sand: Laboratory model testing and in-situ testing

The construction of islands and reef engineering structures in marine environments has been a hot topic in recent years, and calcareous sand, which possesses unique physical properties, is widely distributed on islands and reefs. Due to the properties of calcareous sand, engineering problems such as pile slipping while driving and a low bearing capacity during service can occur. To address the key problem of pile‒soil interactions in calcareous sand foundations, laboratory model and in situ tests were conducted, accounting for factors such as impact energy, relative density, pile-forming method, and pile aspect ratio. First, the penetration mechanism of hammered piles in calcareous sand was studied. Then, the differences in vertical bearing characteristics between hammered and pre-embedded piles under different conditions were explored. The pile driving test results showed that a higher impact energy and lower relative density are more conducive to pile sinking. Moreover, as the number of hammer drops and dynamic penetration resistance increase with increasing burial depth, the pile tip resistance is the main factor limiting pile penetration in calcareous sand. The vertical static loading test revealed that particle breakage accelerates soil redistribution around the pile and that compaction enhances the bearing capacity of the pile. The pile aspect ratio, relative density and pile-forming method also play major roles in the vertical bearing capacity of piles in calcareous sand. In addition, the skin friction of a pile rapidly increases to the ultimate value along a multisegment trend of polyline functions. Similarly, the pile tip resistance rapidly increases at the initial loading stage, exhibiting the behavior of an end-bearing pile. The in situ test results indicated that the pile penetration depth in coral calcareous sand is an important factor affecting the bearing capacity.

Vertical stratification and seasonality of fecal indicator bacteria in New York City playground sandboxes

Sandboxes in public play spaces afford a crucial opportunity for urban children to engage in naturalistic play that fosters development of cognitive, social, and motor skills. As open pits, sandboxes in New York City public playgrounds are potentially exposed to fecal inputs from various sources, including wild and domestic animals. A longitudinal study of thirteen sandboxes located in public playgrounds on the east side of Manhattan reveals ubiquity of the fecal indicator bacteria enterococci and Escherichia coli through all seasons. The highest concentrations of bacteria occur in surface sand (n = 42; mean enterococci 230 MPN/g and E. coli 182 MPN/g dry weight), with significantly lower levels at depths below the surface (n = 35; mean enterococci 21 MPN/g and E. coli 12 MPN/g dry weight), a stratification consistent with fecal loading at the surface. Generalized linear mixed models indicate that sand depth (surface vs. underlayers) is the most influential variable affecting bacterial levels (P <0.001 for both enterococci and E. coli), followed by sampling season (P <0.001 for both). Bacterial concentrations do not vary significantly as a function of playground location or ZIP code within the study area. Children’s exposure while playing in sandboxes likely reaches 105 enterococci and 104E. coli in a typical play period. Microbial source tracking to identify fecal hosts reveals dog, bird, and human biomarkers in low concentrations. Open sandbox microcosms installed at ground level in the urban environment of Manhattan are fouled by enterococci and E. coli within two weeks, while adjacent closed microcosms exhibit no fecal contamination over a 33-day sampling period. Collectively, our results indicate that increasing the frequency of sand refills and covering sandboxes during times of disuse would be straightforward management strategies to mitigate fecal contamination in playground sandboxes.

Comprehensive Solutions to Prevent Larvae Breakout in Water Filtration Systems

The presence of invertebrates in drinking water distribution systems, particularly Chironomidae larvae, has raised concerns among the general public. This study aimed to comprehensively address the issue of larvae breakout in water filtration systems and provide potential solutions to prevent their escape into the water supply. The research investigated various factors contributing to larvae breakout, including the type of filtration column, sand depth, pretreatment methods, and the effective size and uniformity coefficient of sand media. Experimental results revealed that the GAC column, primarily utilized for adsorption, was ineffective in retaining Chironomidae larvae, leading to their escape within a short period. Similarly, the sand filter column, with a design that is currently widely used with sand specifications of an effective size of 0.7 mm and a uniformity coefficient of 1.7, failed to act as a barrier for larvae. Increasing the height of the sand media and applying a pretreatment method, which was expected to prevent larvae from entering the treated water, yielded unsatisfactory results. Our research results show that reducing the uniformity coefficient to 1.5 while maintaining an effective size of 0.7 mm proved to be important in preventing the release of larvae into treated water. The Sand/GAC and Sand/Anthracite systems, by maintaining adjusted media sand specifications, also succeeded in retaining larvae in the filtration system. Additionally, this study emphasized the importance of following the recommended backwash procedure, consisting of specific steps involving air flow, a combination of air and water flow, and final water flow. This sequence effectively removed contaminants, turbidity, and Chironomidae larvae from the filtration media, ensuring improved water quality and system performance. The findings of this study provide valuable insights and recommendations for water treatment plants to address the issue of larvae breakout and enhance water quality.

Measurements of a 20, 440, and 3130 cubic inch air gun or array off Peregian Beach Queensland and Dongara Western Australia highlight small and large scale inhomogeneous sound propagation environments

During the project “Behavioural Response of Australian Humpback whales to Seismic Surveys” three air gun configurations were used to quantify the response of southerly migrating humpback whales to a northerly travelling air gun. Off Peregian Beach, Queensland (26.5o S latitude) a 20 cubic inch (cui) single air gun, 440 cui and 3130 cui arrays were operated while off Dongara, Western Australia (29.5o S) the 440 cui array was operated. At a first glance, we assumed within the respective ∼200 km2 experimental areas sound propagation was reasonably uniform but this was not the case. At Peregian Beach, flat supposedly sandy areas had patchy outcrops of soft “coffee” rock which dramatically increased sound propagation loss while in the north a large arc of hard reef or shallow sand over reef again increased sound propagation loss and acted as an “amphitheatre.” Off Dongara different depths of sand or no sand over a limestone base created variable sound propagation. When comparing Dongara and Peregian Beach the shallow limestone off Dongara increased propagation loss compared to Peregian. This talk will explore some of the idiosyncrasies of air gun propagation and inhomogeneities which can be expected when planning sound exposure experiments.

Reinforcement of Different Sands by Low-pH Bio-Mineralization.

Different sands have significant influences on MICP reinforcement effects. Using calcium carbonate production and bioflocculation lag period as evaluation criteria, this study investigates the optimal theoretical pH values of bacterial solutions with different concentrations. We reinforced four different sands using MICP at the optimal theoretical pH, and based on permeability, moisture retention, raindrop erosion, wind erosion, penetration, and SEM tests, the influence of sand properties on low-pH MICP reinforcement was analyzed and the low-pH MICP mechanism was revealed. The results indicate the following: (1) The optimal theoretical pH values for bacterial solutions with concentrations of 0.67 × 108 cells/mL, 3 × 108 cells/mL, and 10 × 108 cells/mL are 4.5, 3, and 4, respectively. (2) With 0.67 × 108, 3 × 108, and 10 × 108 cells/mL bacterial solutions, the strength of tailings sand containing calcium salt was 21.15%, 44.42%, and 13.61% higher than that of quartz sand, respectively. The effective reinforcement depth of alkaline reclaimed sand was 10, 8, and 6 mm lower than that of neutral calcareous sand, respectively. The strength of fine tailings sand was 70.41%, 58.04%, and 22.6% higher than that of coarse reclaimed sand. The effective reinforcement depth of fine quartz sand was 6, 4, and 4 mm lower than that of coarse calcareous sand. (3) Low pH temporarily suppresses urease activity, delaying calcium carbonate flocculation and enhancing reinforcement uniformity. To achieve optimal reinforcement effects, adjusting the actual optimal pH values of bacterial solution based on sand properties is essential in engineering applications.

Beach erosion aggravates the drastic decline in marine turtle populations in French Guiana

Yalimapo beach, near the Maroni River estuary in French Guiana, is an important turtle nesting site. The interaction of massive mud banks migrating alongshore from the distant Amazon River with discharge from the Maroni River generates strong beach morpho-sedimentary changes. The eventual degradation of the marine turtle nesting habitats resulting from these changes represents a threat to the offspring, and consequently, to the turtle population. Field operator counts of green and leatherback turtle nests were combined with high-resolution topographic measurements of the beach over four field surveys in 2012 and 2014 to map the topographic modifications susceptible to affect nesting on Yalimapo beach. We assumed that the survival of nests was at stake when the depth of sand between the egg chamber and the topographic surface (i.e. the top) of the beach was < 50 cm, and that beach surface lowering > 10 cm represented unfavourable conditions for nest safety with unequal nest survival across the beach. Erosion of the beach surface exceeding a depth of 50 cm therefore results in nest destruction. Digital elevation models were produced to quantify the topographic modification of nesting on Yalimapo beach and highlight the endangered nesting areas. As the modification of the beach is not linear, some sectors are more eroded than others, resulting in unequal nest survival across the beach. Overall, up to 40% of the nests were presumed destroyed over the 2 years of survey, but true losses would depend on the species and the preferential locations of their nesting habitats. The relatively unfavourable conditions that prevailed during the 2 years of the survey are consistent with persistent erosion of Yalimpao beach since 2011. This ongoing erosion could explain in part the drastic decline of the leatherback turtle population in western French Guiana over the period 2001–2018. The substrate quality and dynamics of the nesting beach in relation to the preferred nesting habitat of each species are therefore critical issues that should be considered in the conservation strategies of marine turtles. The beach nesting conditions of marine turtles in French Guiana, as elsewhere, could be further aggravated in the future by climate change effects, including sea-level rise.

Trajectories of plant communities in Massachusetts, USA cranberry farms discontinued from agriculture

Retirement of cultivated croplands creates potential for ecosystem and wetland restoration, but vegetation and soil legacies of cropping influence the development of post-agriculture vegetation. In low-lying coastal watersheds of southeastern Massachusetts, cranberries (Vaccinium macrocarpon Aiton) are cultivated in commercial farm units that are diked, leveled and sanded beds created from historic wetlands. Current low cranberry prices and expanding cranberry production elsewhere now increase the likelihood of cranberry farmland retirement. We quantified the trajectories of plant species richness and cover, and plant characteristics (life form, native or non-native, wetland or non-wetland) in a chronosequence of cranberry farm beds that ranged from cultivated units to those retired from cropping and revegetated for 90 years with no post-cropping management. Species richness increased from active beds to 10–20 year-old beds and subsequently decreased. Post-retirement species richness was overwhelmingly dominated by native species. Shrub and tree richness and cover increased steadily over time. The richness of wetland, upland and facultative species all increased quickly after retirement and then declined in the oldest retired beds. The basal area and canopy cover of red maple (Acer rubrum) and pitch pine (Pinus rigida) increased over time. Vegetation followed a relatively consistent successional trajectory and the plant community after five to nine decades was predominantly forest and dominated by non-wetland plants. Encouragement of long-term persistence of greater diversity and cover of wetland plant species on retired cranberry farms will likely require active hydrological and soil modifications that decrease sand depth and raise water tables.

Method for calculating the uplift capacity of a circular anchor plate at arbitrary depth in sand

Methods for calculating the uplift capacity of horizontal anchor plates have the problem of artificially distinguishing shallow and deep buried types in advance, but the classification standards differ greatly. Based on the application of digital photographic measurement technology in experiment, this paper focuses on a theoretical method for calculating the uplift capacity of horizontal anchor plate in sand at arbitrary depth without distinguishing shallow and deep burial types. The results show that the sliding surface in the soil extends to ground surface in approximately a straight oblique line at shallow burial depths, then gradually confined within the soil as a balloon shape as the burial depth increases, and further shrinks toward the anchor plate. This change of sliding surface has no absolute boundary but undergoes continuous evolution, and can be described by a morphological function of logarithmic spiral line, which is used to develop a unified mechanical model, and a theoretical method for calculating uplift capacity is deduced and established. The new mechanical model well reflects the continuous variation of the sliding surface, and comparison with other four methods on 8 experimental cases show that the new calculation method has good adaptability for different types of burial depths.

An Experimental Study on optimizing Wastewater Filtration through Conventional and Capped Rapid Sand Filter

Abstract: Rapid sand filtration is a widely adopted technique for purifying water in various applications, ranging from municipal water treatment plants to industrial processes. This abstract provides an overview of the rapid sand filter, highlighting its key principles, advantages, and applications. The rapid sand filter is a gravity-driven filtration system that utilizes a bed of sand as the primary filtration medium. Water flows through the sand bed under gravity or low-pressure conditions, undergoing physical andbiological processes that remove suspended solids,pathogens, and other impurities. The sand bed acts as a physical barrier, trapping and retaining particles while allowing the passage of clean water. This abstract discusses the key factors influencing the efficiency of rapid sand filters, including sand grain size, uniformity, and depth. The control of filtration rate, backwashing frequency, and the use of coagulants or flocculants are also addressed, as they significantly impact the filter's performance. Proper maintenance and monitoring are crucial to ensure optimal filter operation and prevent clogging or biofilm formation. Rapid sand filtration offers several advantages, such as simplicity, cost-effectiveness, and ease of operation. It is capable of achieving high removal efficiencies for suspended solids, turbidity, and certain pathogens, making itsuitable for a wide range of water treatment applications

LiDAR-change-based mapping of sediment movement from an extreme rainfall event

ABSTRACT Mapping landscape change at fine scales (e.g. <1.0 m resolution) using airborne LiDAR data from manned aircraft is a significant challenge. This challenge is magnified in disaster response contexts. A combination of collection and processing factors contributes to horizontal and vertical errors (and resulting uncertainty) in each pre- and post-LiDAR derived digital elevation model (DEM). Subsequently, the errors in the change surface from the two (or more) DEMs are an accumulation of the errors in the individual DEMs. Thus, reliable mapping erosion/deposition changes at sub-meter precision in change detection studies using LiDAR data is largely the domain of terrestrial LiDAR or sUAS with LiDAR scanners rather than manned aircraft. Unfortunately, terrestrial and sUAS LiDAR scanners are not well suited for mapping large areas and sUAS collections are subject to additional airspace constraints compared to manned aircraft. In this study, we probed one of the significant issues in airborne LiDAR change projects – vertical height errors from sequential flight lines. A simplified solution for determining flight line vertical biases in areas of low topographic relief with natural cover types was developed and tested for normalizing point clouds. The approach was tested in a fine-scale erosion/deposition study from an extreme rainfall event that eroded and deposited sand at depths of about 1.0 m. Airborne LiDAR had been collected prior to the rainfall event, and another airborne LiDAR collection was made 1 month after the event. Eleven field campaigns to collect reference data and visit anomalies in the change surface were conducted in a 15-month period after the event, beginning 25 February 2016 and ending 8 May 2017. The validation results indicate accuracies for the pre-event and post-event LiDAR derived DEMs were 7.8 cm and 13.0 cm RMSE, respectively. After modeling vertical errors and corrections applied to the post-event point clouds, the RMSE for the post-event DEM was 8.3 cm. In the depositional use case, 27 locations were sampled with auger boreholes/sand pits and compared with LiDAR-based change. The LiDAR-based change detection analysis resulted in predicted sand depth accuracies of 94% with a mean error of 4.7 cm.

Effect of filtration rates on the performance and head loss development in granular filters during the post-treatment of anaerobic reactor effluent.

This study investigated the performance of a granular filtration system (GFS) composed of a rock filter (RF), a rapid sand filter (RSF), and an activated carbon filter (ACF), applied to the post-treatment of an anaerobic reactor effluent. Four filtration rates (FR) were applied to the GFS (in m3·m-2·d-1): 100-60-60, 100-90-90, 200-120-120, and 200-160-160, for RF-RSF-ACF, respectively. A clarified final effluent with low turbidity (~ 10 NTU), solids (~ 6.5mg TSS.L-1), and organic matter content (~ 40mg COD.L-1) was obtained when the GFS worked with FR up to 100-90-90 m3·m-2·d-1. For higher FR, the effluent quality was a little poorer. Principal component analysis showed when the RSF operated at 120 or 160 m3·m-2·d-1, it presented an effluent with higher turbidity which did not affect negatively the ACF performance. The hydraulic load limits in the RSF were reached in periods of 45, 30, and 24.5h for the FR of 60, 120, and 160 m3·m-2·d-1, respectively, and head loss analysis depicted a more distributed solid retention through the sand depth with the lower FR. Thus, the results revealed that the RF-RSF-ACS system is a promising alternative for effluent polishing of anaerobic reactor, especially when the FR is set at 90 m3·m-2·d-1 or even higher.

Review of Slow Sand Filtration for Raw Water Treatment with Potential Application in Less-Developed Countries

Providing safe drinking water to people in developing countries is an urgent worldwide water problem and a main issue in the UN Sustainable Development Goals. One of the most efficient and cheapest methods to attain these goals is to promote the use of slow sand filters. This review shows that slow sand filters can efficiently provide safe drinking water to people living in rural communities not served by a central water supply. Probably, the most important aspect of SSF for developing and less-developed countries is its function as a biological filter. WASH problems mainly relate to the spread of viruses, bacteria, and parasites. The surface and shallow groundwater in developing countries around urban areas and settlements are often polluted by domestic wastewater containing these microbes and nutrients. Thus, SSF’s function is to treat raw water in the form of diluted wastewater where high temperature and access to nutrients probably mean a high growth rate of microbes and algae but probably also high predation and high efficiency of the SSF. However, factors that may adversely affect the removal of microbiological constituents are mainly low temperature, high and intermittent flow rates, reduced sand depth, filter immaturity, and various filter amendments. Further research is thus needed in these areas, specifically for developing countries.

Numerical investigation on the pull-out capacity of suction anchors in sand considering torsional and mooring line effects

Torsional pullout of suction anchors may occur during installation due to improper positioning or deviations caused by current forces, but less attention has been paid to the effect of torsion on the pull-out capacity of suction anchor in existing literatures. This paper therefore numerically investigates the pull-out capacity and failure mechanism of suction anchors in sand considering both torsional and mooring line effects using the advanced SIMSAND constitutive model. It is found that considering torsional influence causes a significant reduction in the pull-out capacity of suction anchor in sand under horizontal and inclined loading. The case with the optimal padeye depth of 0.7L produces the largest pull-out capacity and the greatest reduction in the pull-out capacity due to torsion. The dimensionless pull-out capacity for the case without mooring line is approximately 24% higher than or almost twice that of the case with mooring line in scenarios without or with torsional condition. Based on the findings, a new framework for estimation of the pull-out capacity of the suction anchor at the optimal padeye depth in sand considering torsional and mooring line effects is finally proposed which may benefit the design of suction anchor in scenarios with torsion in the real practice.

Long coleoptile genotype and soil texture interactions determine establishment success and early growth parameters of wheat sown at depth

Long coleoptile (LC) - wheat genotypes sown deeper (> 10 cm) than current practice (< 5 cm) enables earlier deep sowing into subsurface soil moisture. The LC genotype shows promise to broaden sowing windows and remove reliance on the shifting seasonal break for crop establishment. The suitability of this sowing strategy to the highly variable soils of the southern Australian wheatbelt warrants investigation to identify suitable environments for potential establishment benefits. We conducted controlled environment room (CER) and field experiments using pairs of near-isogenic-lines (NILs) that differed genetically only for coleoptile length. The experiments investigated the suitability of deep sown (12 cm) LC wheats in soils with different texture (sand versus loam). The CER experiment identified that LC genotypes exhibited greater emergence and early seedling growth, producing greater shoot and root biomass, when deep sown (12 cm) in loam. While LC and short coleoptile (SC) genotypes produced similar shoot growth when sown at depth in sand, LC produced greater root biomass reflected in more seminal roots. In the field on sand, LC and SC had similar emergence and early shoot growth characteristics at all sowing depths (5, 8 and 10 cm). However, the heavy-textured, loam soil reduced seedling emergence and restricted leaf growth with deep sowing (12 cm) in the SC. Our results indicate that the LC trait was more critical for plant emergence and early growth parameters (shoot and root biomass) from depth in a heavier textured loam compared with a sand. By identifying environments that will likely benefit most from deep sown LC, we are one step closer to adapting crop production to shifting rainfall patterns in southern Australia.

Bioindication of Bottom Sediments of the Gulf of Finland by the Composition of Meiobenthos in Combination with Biotesting and Chemical Analysis

The question of the possibility of using meiobenthos to monitor the state of bottom sediments (BS) in the Baltic Sea, where bottom macrofauna are unstable due to hypoxia, is of interest. The parameters of meiobenthos and the physicochemical characteristics of BS and bottom water were studied, and the toxicity of BS was determined by the survival of the amphipod Gmelinoides fasciatus in 10-day tests for 11 stations in the brackish part of the Gulf of Finland (depths of 10–52 m). Principal component analysis revealed two factors explaining 67% of the variability of the variables, and groups of stations similar in terms of conditions. Factor 1 combined nine related variables (depth, metal concentrations and fraction of sand in BS, ratio of nematodes and copepods (N/C index) and survival of amphipods), and factor 2 combined four variables (organic matter and polyaromatic hydrocarbons in BS, phosphates in water and the number of meiobenthos). Thus, bioindication of the environment by meiobenthos is promising, but requires an integrated approach to be applied in monitoring.