Cm Of Sand Research Articles

Development Modeling of Phormia regina (Diptera: Calliphoridae).

A series of experiments were conducted on Phormia regina, a forensically important blow fly species, that met the requirements needed to create statistically valid development models. Experiments were conducted over 11 temperatures (7.5 to 32.5 °C, at 2.5 °C intervals) with a 16:8 L:D cycle. Experimental units contained 20 eggs, 10 g of beef liver, and 2.5 cm of sand. Each life stage (egg to adult) had five sampling times. Each sampling time was replicated four times for a total of 20 measurements per life stage. For each sampling time, the cups were pulled from the chambers, and the stage of each maggot was documented morphologically through posterior spiracular slits and cephalopharyngeal development. Data were normally distributed with the later larval (L3m) and pupation stages having the most variation within and transitioning between stages, particularly between 12.5 °C and 20.0 °C. The biological minimum was between 10.0 °C and 12.5 °C, with little egg development and no egg emergence at 7.5 °C and no maturation past L1 at 10.0 °C. Phormia regina did not display increased mortality associated with the upper temperature of 32.5 °C. The development data generated illustrate the advantages of large data sets in modeling blow fly development and the need for curvilinear models in describing development at environmental temperatures near the biological minima and maxima.

Impacts of vegetation and topsoil removal on soil erosion, soil moisture, and infiltration

AbstractSoil erosion by water is a critical environmental problem that affects a large land area globally and is expected to increase substantially as a result of climate change‐induced rainfall intensification. This study sought to determine the impacts of soil mechanical disturbance and topsoil removal on soil erosion and deposition, soil moisture, soil water infiltration, and vegetation type in a central Texas subtropical grassland setting. The removal of topsoil increased soil erosion and caused changes in soil texture, soil moisture, infiltration rate, and the vegetation community within the disturbed area. Soil texture shifted from clay to sand dominated as sand particles were eroded from an upland area. This shift in soil texture led to decreased volumetric soil moisture (−14.6%) as compared to an adjacent undisturbed location. The removal of topsoil also led to an invasion of non‐native grasses that now dominate the vegetated portions of the disturbed area. Erosion and deposition measurements indicated an uneven gain and loss of soil across the disturbed area, but on average 0.85 cm of sand was deposited during the 1‐month study period. Our results show that high levels of erosion are occurring and degrading the immediate landscape, which is likely contributing a large amount of sediment to a nearby waterway, posing a potential water quality threat to an important surface water body.

Performance Evaluation of Mentha longifolia Plant for Domestic Waste water Treatment under arid climate conditions (Tamanrasset region, Algeria)

The objective of this work is to highlight the purification performance of the Mentha longifolia plant for wastewater under a horizontal flow regime and a hot and dry (arid) climate. In this research, we made a comparison between a planted bed of Mentha longifolia and a non-planted bed (control) as well as the study of the performance of the Mentha longifolia to purify the wastewater. The study is carried out according to an experimental pilot in the urban wastewater treatment zone within the National Sanitation Office (NSO) in Tamanghasset. The experimental pilot consists of pots of capacity 130 liters filled from bottom to top on a thickness of 45 cm of gravel (15 / 25mm) of 10 cm of sand. The pot is planted with young stems of Mentha longifolia (36 stems / m2) and the other non-planted pot is taken as a control. The pots are fed by urban wastewater (18 liters / day), once a week. The water obtained after 5 days is collected in a container located under the pot. The performance information shown is for the periods from the month of January - April 2021.After four months of follow –up, we obtained the pollutant removal results with the following percentages: COD (77.74%), BOD5 (72.47%), MES (87.78%), NO3-(63.40%), NO2- (62.03%), PO43- (62.77%), E. coli (99.43%). The existence of the plant Mentha longifolia in planted beds maintains a sufficient porosity that prevents clogging. The significant reduction of pollutants and pathogenic microorganisms allows us to consider the reuse of treated water in agriculture and industry.

Low-cost onsite selection of suitable unplanted sand drying bed structure for faecal sludge treatment in less developed countries: A case study of Yaounde in Cameroon

Abstract There are lots of drying bed structures in the literature that are planted or unplanted but few indicate reasons behind their choice. As this technology is widely spread in less developed countries, identification and analysis of selection criteria for appropriate unplanted faecal sludge drying beds are necessary. This article analyses a case study in Yaounde for domestic septage over three bed structures for which sludge and percolates parameters are analyzed and treatment performance assessed through 10 technical criteria using a low-cost infrastructure with a minimal footprint. These are related to mass and volume reduction, organic and mineral pollution, as well as drainage capacity. The bed structure used is constituted of gravel and sand with 20–30 cm thickness. These beds recorded more than 85% reduction in organic and suspended matter and a 70% reduction in nitrates and lead concentration with at least 38% of dissolved material and chemicals removed. Considering the suggested criteria, a bed with 20 cm of gravel and 20 cm of sand was found to be the most efficient for material and pathogens removal. This method provides an interesting selection option with low-cost infrastructure, material, and operation for popular selection of suitable faecal sludge treatment technology in less developed countries.

Use of constructed wetlands to prevent overloading of wastewater treatment plants

The fluctuation in the number of people in tourist areas affects the wastewater quality and quantity. Constructed wetlands (CWs) aim to simulate physical, chemical, and biological processes occurring in natural environments for wastewater treatment and are considered a sustainable system. The current study aimed at evaluating the effectiveness of in-vessel CWs for supporting the wastewaters treatment plants in periods of overloading. Such approach can be quickly implementable, economic, and the CWs can be fast regenerated in the framework of sustainable good practices. Three pilot scale CWs were prepared in as many containers layering 10 cm of gravel, 60 cm of sand and 10 cm of gravel, and placing pieces of giant reed rhizomes in the upper layers. The bottom of each CW had a tap, and CWs were irrigated with a real municipal sewage three times a week. Before each new irrigation, the tap was opened, and the effluent collected for determining gross parameters, elemental composition, and contaminants of emerging concern (CECs).CWs significantly reduced almost all gross parameters considered and half the CECs, except for a couple of metabolites of corresponding parental compounds. With regards to the potentially toxic elements, all reduced their concentration from the influents to the effluents.The results of this study were promising and highlighted good efficiency of constructed wetlands as pre-treatment of real municipal sewage to reduce the overloading of the wastewater treatment plant.

Using A Subsurface Vertical Flow System to Remediate Municipal Wastewater

The goal of this study is to determine the efficacy of plants in the treatment of municipal wastewater (MWW) utilizing the aquatic plant common reed, also known as Phragmites australis. Two glass basins with dimensions of (60 cm x 26 cm) and a height of (60 cm x 26 cm) have been developed for this purpose (30 cm). In this investigation, two basins were employed: one served as a reference, while the other was used to conduct tests using synthetic and actual city wastewater. The plant treatment basins with a vertical subsurface flow (VSSF) system was used in this investigation because it provides greater ventilation. Furthermore, the retention duration is many hours due to water molecules penetrating the basin's layers of packing materials, which have a rather high hydraulic conductivity. Three layers of aggregates, sand, and agricultural sand were used to cover the basins' bases: the first layer was 3 cm of aggregates, the second was 3 cm of sand, and the final layer was 4 cm of agricultural sand. Before beginning the experiment, the plants were acclimated for two weeks. To imitate municipal wastewater, lab-created synthetic wastewater was employed. Samples were collected and tests were performed after four weeks of running the trials to determine certain significant pollution indicators and their elimination percentage. TDS= 20.6 %, TSS= 65 %, BOD5=75 percent, COD=64.1 %, and TH= 47.2 % were the findings. The capacity of Phragmites australis to function as a biofilter in the treatment process was demonstrated by its use in the phytoremediation of municipal wastewater.

Ebullition-facilitated mobilization of trapped dense non-aqueous phase liquid at residual saturation from sandy sediments.

Gas ebullition can mobilize dense non-aqueous phase liquids (DNAPLs) from sediments to the overlying water column, increasing the DNAPL-impacted area and posing serious challenges to the remediation and management of contaminated sediments. Despite this, there have been few laboratory studies focused on gas ebullition-facilitated transport of DNAPL. In this study, bubble-facilitated transport was investigated by injecting gas (air or nitrogen) at 1mL/min through a creosote source zone (∼25% saturation) capped with sand layers of different thicknesses. Three short-term experiments (8.3-8.7h) were capped with 11.4, 7.0 or 4.5cm of sand to estimate DNAPL flux. One long-term experiment (30 days) was capped with 8cm of sand to investigate DNAPL removal. Heptane placed on a layer of water above the sand was used as a solvent trap and analyzed for petroleum hydrocarbons (PHCs). Results showed that creosote travelled as thin coatings and films surrounding gas bubbles migrating out of the source zone. Gas invasion was dominated by capillarity in the 11.4cm-thick sand layer and by fracturing in the 7.0 and 4.5cm-thick sand layers. Migration through these fractures often led to the formation of creosote tails on mobilized bubbles that drained towards the rear end of the bubble. The mass released decreased exponentially with sand cap thickness. In the long-term experiment, images showed significant depletion of the source zone in 30 days. Linear regression analysis showed that relationships with high predictive capabilities for ebullition-facilitated fluxes of hydrophobic organic contaminants can be obtained by incorporating gas ebullition flux and source strength, based on results from this study along with others from the field and laboratory. To our knowledge, this is the first study to compile and integrate data collected from laboratory and field studies to develop an assessment tool to facilitate the management of contaminated sediments affected by gas ebullition.

Predictive modelling of a rapid stratified bed filter for turbidity removal from surface water

The objective of the present work was to evaluate the hydrodynamic behaviour of a stratified bed filtration column consisting of 4 cm of sand and 2 cm of limestone to remove turbidity and measuring the head loss through the filter in several runs. In this study, two types of sand were used as filtering bed material, one fine and one medium. Crushed limestone was also available. These materials were characterized to determine the average particle diameter, porosity, and permeability coefficient. These were respectively 1.7∙10 –4 m, 336.96 and 0.68 m∙day –1 for fine sand, 3.3∙10 –4 m, 654.24 and 2.59 m∙day –1 for the medium sand and 1.26∙10–3 m, 388.8 and 8.64 m∙day–1 for crushed limestone. Using these materials, hydrodynamic analyses were carried out using clean water under rapid filtration conditions. In these analyses, different filtration rates were determined to be used in each experiment. Once the filtration rates were determined, the filtration analysis was performed with synthetic turbid water prepared at 8 NTU using tap water and bentonite. From the results obtained, a predictive model was developed based on total head losses for the evaluated filter, maintaining the rapid filtration condition. As a result, a turbidity removal efficiency of 97.7% was obtained with a total head loss of 17.8 cm at a filtration rate of 153 m·day –1. The developed model predicted head loss as a function of operating time, filtration rate, and filter depth to maximise turbidity removal. The model showed excellent prediction accuracy with R2 of 0.9999, which indicates that the model predictions are not biased. It was concluded that, due to the porosity of these materials, a stratified bed of sedimentary rocks has a great potential to be used in surface water filtration processes, which implies that it could be used at the rural community level as a form of water treatment, since the

Scientists may have discovered why Speedy Gonzales is always fast

Almost every person has walked or run on the beach at some point in their life. Moving on loose sand feels more challenging than walking on a sidewalk. In general, walking on sand requires more work and energy and this is not unique to humans. Now, you may also be familiar with Speedy Gonzales, a Looney Tunes cartoon mouse who runs super-fast all the time. You may wonder how Speedy can always run so fast across all the different terrains that he encounters, but a very similar looking animal to Speedy Gonzales in real life, the kangaroo rat (Dipodomys deserti), may prove that the cartoon's versatility is not so far off reality.Some researchers have previously tested different types of animals, such as lizards and ostriches, running over solid surfaces versus sandy surfaces. This line of research motivated Joseph Hall (Washington State University, USA), Craig McGowan (University of Idaho, USA) and David Lin (Washington State University) to study a hopping animal, the kangaroo rat, to expand on our current understanding of the effects of different types of ground on animal movements. These little hopping animals are equally adept moving across rocky and sandy terrains, both of which exist in their natural desert habitat. So, the researchers cleverly developed the very first variable terrain rotatory treadmill and put these animals to the test hopping on a solid and a sandy surface while controlling the speed and recording video of the animals’ manoeuvres.However, before the kangaroo rats were allowed to hop in place, the team had to ensure that the level of sand on the treadmill was sufficient to prevent the animal from touching the solid base beneath. To do this they designed a device that can measure how far the rodents’ feet would penetrate the sand and determined that at least 1.5 cm of sand was sufficient.Although the six desert kangaroo rats had to move at five different speeds, ranging from 1.25 to 2.25 m s−1, Hall and colleagues only analysed the motion of the little rodents’ hind legs at 1.8 m s−1, the speed at which these animals tend to hop in the wild. Comparing the animals’ hopping styles on solid and sandy surfaces, they found no significant difference in the amount of time the animals’ feet were in contact with the ground or the distance covered during each hop. Also, the researchers found no meaningful difference in the rodent's speed and acceleration between the two different surfaces, although the animals were more crouched when hopping on sand.Even though the environment has induced changes in the running styles of some animals, it appears that kangaroo rats have evolved so that changes in the surface they hop around on does not affect their speed. They maintain very similar physical hindlimb movements regardless of the firmness of the surface that they are moving over, suggesting that they are finely tuned to their environment. And even though Speedy Gonzales is a runner and kangaroo rats hop, the discovery that kangaroo rats are perfectly tuned to move on hard and soft surfaces could hold the key to Speedy's super-fast reputation.

Sand-capping stabilizes muddy sediment and improves benthic light conditions in eutrophic estuaries: Laboratory verification and the potential for recovery of eelgrass (Zostera marina)

Decades of eutrophication have increased water turbidity in Danish estuaries and led to light limitation of eelgrass (Zostera marina) growth. Former eelgrass areas are now denuded and consist of organic-rich muddy sediment with frequent resuspension events that maintain a high turbidity state. In addition, low anchoring capacity of eelgrass in the soft organic-rich sediments has contributed to eelgrass loss. When navigation channels in Danish estuaries are dredged, large amounts (~100.000 m3) of sandy sediment are shipped to remote dumping sites. Instead, we suggest that the dredged sand is used to consolidate adjacent muddy areas. We demonstrate in the present laboratory study that capping of fluid muddy sediment with 10 cm of sand is feasible without any vertical mixing and that this marine restoration approach potentially can lower the magnitude and frequency of resuspension events. Erosion of suspended solids change from 5 g m−2 min−1 above muddy sediment as to about 0.2 g m−2 min−1 after sand-capping, implying that the application of sand can improve light conditions. Moreover, since erosion thresholds increase from about 10–12 cm s−1 for mud to 40 cm s−1 for sand-capped mud the anchoring capacity of rooted vegetation is increased. However, the full potential of sand-capping to facilitate restoration of otherwise lost eelgrass habitats requires verification by large-scale field experiments.

Effect of flow rate on the performance of Biosand Filter

Lack of access to safe drinking water is an issue in some areas where centralized water treatment is not possible, the biosand filter (BSF) one of several such point-of-use technologies is available. This study was conducted in Côte d’Ivoire to evaluate the effect of flow rate on the performance of the BSF. Three biosand filter (BSF) built in Poly vinyl chloride was used to investigate the effect of three flow rates (1.95 L/d in BSF1; 3.9 L/d in BSF2 and 7.8 L/d in BSF3) for 91 days. Each BSF was filled with 15 cm of gravel, 90 cm of sand and 40 cm of supernatant water. Physical and chemical parameters were analyzed in raw water and filtered water with standards methods. The results showed that the percentage removal of TSS approximately the same for all filters. Ammonium concentrations ranged from 37 to 170 μg.L-1, 110 to 190 μg.L-1 and 150 to 278 μg.L-1 for filtered waters of BSF1, BSF2 and BSF3, respectively. Nitrite concentrations in filtered waters of BSF1 (2 - 33 μg.L-1) were less than those of BSF2 (5 - 45 μg.L-1) and BSF3 (7 - 49.5 μg.L-1). Nitrate concentrations in filtered waters of BSF2 (1.9 to 4 mg.L-1) and BSF3 (1.6 to 4.2 mg.L-1) were higher than those of BSF1 (0.6 to 2.3 mg.L-1). Chemical Oxygen Demand removal efficiency for BSF3 (68.2 ± 9.5%) was lower compared to BSF2 (82.6 ± 3.8%) and BSF1 (93.7 ± 2.8%). The flow rate has an influence only on the removal of ammonium, nitrite, nitrate and Chemical Oxygen Demand. The best treatment results were obtained with the minimum flow rate (1.95 L/d).

Tea Bag Index to Assess Carbon Decomposition Rate in Cranberry Agroecosystems

In cranberry production systems, stands are covered by 1–5 cm of sand every 2–5 years to stimulate plant growth, resulting in alternate layers of sand and litter in soil upper layers. However, almost intact twigs and leaves remain in subsurface layers, indicating a slow decomposition rate. The Tea Bag Index (TBI) provides an internationally standardized methodology to compare litter decomposition rates (k) and stabilization (S) among terrestrial ecosystems. However, TBI parameters may be altered by time-dependent changes in the contact between litter and their immediate environment. The aims of this study were to determine the TBI of cranberry agroecosystems and compare it to the TBI of other terrestrial ecosystems. Litters were standardized green tea, standardized rooibos tea, and cranberry residues collected on the plantation floor. Litter decomposition was monitored during two consecutive years. Added N did not affect TBI parameters (k and S) due to possible N leaching and strong acidic soil condition. Decomposition rates (k) averaged (mean ± SD) 9.7 × 10−3 day−1 ± 1.6 × 10−3 for green tea, 3.3 × 10−3 day−1 ± 0.8 × 10−5 for rooibos tea, and 0.4 × 10−3 day−1 ± 0.86 × 10−3 for cranberry residues due to large differences in biochemical composition and tissue structure. The TBI decomposition rate (k) was 0.006 day−1 ± 0.002 in the low range among terrestrial ecosystems, and the stabilization factor (S) was 0.28 ± 0.08, indicating high potential for carbon accumulation in cranberry agroecosystems. Decomposition rates of tea litters were reduced by fractal coefficients of 0.6 for green tea and 0.4 for rooibos tea, indicating protection mechanisms building up with time in the tea bags. While the computation of the TBI stabilization factor may be biased because the green tea was not fully decomposed, fractal kinetics could be used as additional index to compare agroecosystems.

Short-Term Effects of Thin-Layer Sand Placement on Salt Marsh Grasses: A Marsh Organ Field Experiment.

Salt marshes can build in elevation with sea-level rise through accumulation of inorganic sediment and organic matter, but marshes worldwide are under threat of drowning due to rapid rates of sea-level rise that outpace natural marsh building rates. The application of a thin layer of sediment to the marsh surface (thin-layer placement [TLP]) is a tool to build elevation and decrease flooding stress, but its effects on marsh plants are understudied, especially in New England. In a novel application of a marsh organ experiment (i.e. rows of pots at different elevations), the addition of 10 cm of sand to pots planted with Spartina alterniflora and Spartina patens resulted in fewer stems than controls for S. patens but not S. alterniflora after 2 months. However, total biomass and root mass were not significantly impacted for either species, suggesting plants will fully recover from TLP over longer timescales. Effects of TLP on biomass and stem density did not vary significantly by elevation. Although long-term research is still needed, short-term equivalency in biomass between TLP treatments and controls suggests TLP of 10 cm is a promising strategy to enhance the ability of marshes to build vertically as sea level rises in New England.

Study on the Development of Spiral babylonia snail Tiger Snail Juvenil Eggs (Babylonia spirata Linnaeus, 1758) in the Laboratory

Several marine gastropods are known to have high economic value, one of which is the Spiral babylonia snail. They commonly exploited for meat, shell, or operculum. Tiger snail meat is commonly exported and consumed by fishermen. Its shell is used as a material for industrial lime and for omamen. Operculum is commonly used as a medicinal and perfume ingredient). However, the recent production has decreased due to the limited information of seasonal catch. One way to overcome these obstacles is through culture activities. The provision of seeds is an important link in the culture system, therefore the study of the spawning process and larval development is an important requirement for the development of larval rearing techniques. This study aims to determine the development process of juvenil eggs and the survival rate of tiger snails reared in the laboratory.. The study was conducted at the Laboratory of Marine Farm Subdivision in Kudus, Pt Pura Bahari, Jepara Regency. This sudy used experimental method with descriptive data analysis. Adult tiger snails were caught from Bunga waters, Demak. The snails were reared in a rectangular tube filled with 15 cm filtered sea water and 5 cm of sand. Egg capsules were reared in a 4 liters circular tube with continuous aeration. The hatched larvae were reared in a 300 liters circular tube filled with filtered seawater, continuously aerated and fed with Chlorella plankton . Our result showed that tiger snails spawn naturally and produce egg capsules. The incubation period for the capsule is 6 days, then develop into veliger larva for 12 days. The veliger larvae metamorphosed,and become juvenil. The lowest survival rate observed in the veliger stage. The survival rate of the egg and the intracapsular trochopore stages were quite high (tube I = 98.413%; tube II = 98.238%; tube III = 90.476%), then the lowest was in the veliger stage (tube I = 3,468%; tube II = 2.603%; tube III = 2,598%) and the juvenil stage is quite high compared to the previous phase (tube I = 3,413%; tube II = 2,479%; tube III = 2,351%).

Effects of surface materials of self-draining beds on cattle behavior in a temperate climate.

ObjectiveThe objective of the present experiment was to construct self-draining beds to keep surface bedding materials clean and dry for beef cattle comfort in a temperate climate.MethodsIn Experiment 1, a self-draining bed was covered with sand at depths of 10 cm (S-10a), 15 cm (S-15), and 20 cm (S-20) respectively. In Experiment 2, self-draining beds of different sizes were covered with 10 cm of sand (S-10b) and wood shavings (WS) at depths of 15 cm and 20 cm (WS-15 and WS-20). Fifteen cattle were engaged to evaluate the comfort of self-draining beds covered with different bedding materials.ResultsNo cattle lay in the feed alley and cattle spent more time lying on S-10a than S-15 or S-20 in Experiment 1 (p<0.01). No difference in lying time was detected between S-15 and S-20 (p>0.05). In Experiment 2, no cattle selected the feed alley as the lying area. Cattle preferred WS-15 as the lying area and time spent lying on WS-20 was slightly higher than on S-10b (p<0.05). Feces weight was higher in the feed alley than in the different bedding areas in both Experiments 1 and 2 (p<0.01).ConclusionSand-bedding depth at 10 cm and WSs at 15 cm above the self-draining bed can provide for the lying comfort of beef cattle. Design of a special feed alley to hold most of the feces to keep bedding materials clean and dry is desirable for organic beef cattle in a loose barn.

Genome-wide Association Study (GWAS) for Mesocotyl Elongation in Rice (Oryza sativa L.) under Multiple Culture Conditions.

Mesocotyl is a crucial organ for pushing buds out of soil, which plays a vital role in seedling emergence and establishment in dry direct-seeded rice. However, the genetic mechanisms of mesocotyl elongation remains unclear. In our study, 208 rice accessions were used to identify the SNPs significantly associated with mesocotyl length under various culture conditions, including sand, water and soil. The mesocotyl length ranges from 0 to 4.88 cm, 0 to 3.99 cm and 0 to 4.51 cm in sand, water and soil covering, respectively. A total of 2,338,336 SNPs were discovered by re-sequencing of 208 rice accessions. Genome-wide association study (GWAS) based on mixed linear model (MLM) was conducted and 16 unique loci were identified on chromosomes 1, 2 (2), 3, 4, 5 (2), 6 (2), 7, 8, 9 (2) and 12 (3), respectively, explaining phenotypic variations ranging from 6.3 to 15.9%. Among these loci, 12 were stable across two or more environments. Ten out of the sixteen loci coincided with known genes or quantitative trait locus (QTL), whereas the other six were potentially novel loci. Furthermore, five high-confidence candidate genes related to mesocotyl elongation were identified on chromosomes 1, 3, 5, 9 and 12. Moreover, qRT-PCR analysis showed that all the five genes showed significant expression difference between short-mesocotyl accessions and long-mesocotyl accessions. This study provides new insights into the genetic architecture of rice mesocotyl, the associated SNPs and germplasms with long mesocotyl could be useful in the breeding of mechanized dry direct-seeded rice.

Thin-layer fine-sand capping of polluted sediments decreases nutrients in overlying water of Wuhan Donghu Lake in China.

Capping water body sediments with a thin layer of sand is an effective technique to decrease nutrient concentrations in the water column and accelerate ecological restoration of eutrophic water bodies. However, long-term effects of thin-layer sand capping in shallow lakes are reported less often. Using clean fine sand and geotextile mats as capping materials for sediments collected from Wuhan Donghu Lake in China, we designed a 290-day tank experiment with 3 cm of sand capping at four percentages of sediment coverage from 25 to 100% and a control (no capping). We monitored total nitrogen (TN), total phosphorus (TP), nitrate (NO3-), ammonia (NH4+), and soluble reactive phosphorus (SRP) in the overlying water every 7 days. Mean TN and NO3- concentrations were significantly the lowest (P < 0.05) at 50% coverage. Further increase in coverage kept them slightly fluctuating. NH4+ concentration was significantly lowest (P < 0.05) at 75% coverage. The relation between coverage and mean TP and SRP concentrations indicated that 75% coverage significantly decreased (P < 0.05) them, and increasing coverage to 100% decreased them even more. The fluxes of TN and TP estimated between sediments and overlying water showed that the thin fine-sand layer significantly increased the function of sediments as a sink of TN from overlying water and the potential of a sand layer to block release of TP from sediments (P < 0.05). Our results suggested that if thin-layer sand capping were applied to Wuhan Donghu Lake, more than 50% coverage is required to decrease nutrients in the lake's water.

Stabilization on Expansive Soil with Different Sand Layers

Problematic Soil improves by better root growth, water movement, and also by mixing portions of the soil profile, to provide more uniform texture. As a ground improvement technique to improve the strength of problematic soils and this study is carried out to understand the settlement behaviour of layered soils. The soil which is collected was found to be problematic in nature, which is more swelling in nature. The samples of soil are collected the from Mudichur road, Tambaram. The sand used in this study is taken from nearby site and is used to improve the problematic soil by forming a layer of required thickness. The preliminary tests are conducted on the soil samples to determine their properties as per IS standards. After the preliminary test, the plate load tests are performed on the soil with square plate (10 mm x 10mm) in order to know the bearing capacity of soil. The load tests are performed on sand and clay layers with varying thickness of 5cm, 10 cm and 15 cm of sand over clay soil. From the plate load test the load- settlement behaviour of soil layers are studied. It can be conclude that if different layers of sands are provided over Problematic soil then It gets enough Load bearing resistance which can be further gets implemented during Highways constructions. The results says that of 15 cm layer of sand shows maximum load bearing capacity &amp; shown better load – settlement graphs as well.

Stabilizing Property of Expansive Soil with Different Sand Layers

Sweeping Soil improves by better root development, water development, and furthermore by blending bits of the dirt profile, to give progressively uniform surface. As a ground improvement method to improve the quality of dangerous soils and this examination is done to comprehend the settlement conduct of layered soils. The dirt which is gathered was seen as risky in nature, which is all the more expanding in nature. The examples of soil are gathered from in and around Chennai. The sand utilized in this investigation is taken from close by site and is utilized to improve the hazardous soil by shaping a layer of required thickness. The primer tests are directed on the dirt examples to decide their properties according to IS models. After the fundamental test, the plate load tests are performed on the dirt with square plate (10 mm x 10mm) so as to know the bearing limit of soil. The heap tests are performed on sand and mud layers with fluctuating thickness of 5cm, 10 cm and 15 cm of sand over mud soil. From the plate load test the heap settlement conduct of soil layers are examined. It very well may be reason that on the off chance that various layers of sands are given over Problematic soil, at that point It gets enough Load bearing obstruction which can be further gets actualized during Highways developments. The outcomes says that of 15 cm layer of sand shows most extreme burden bearing limit and indicated better burden – settlement diagrams also.

A Bayesian Approach for Remote Depth Estimation of Buried Low-Level Radioactive Waste with a NaI(Tl) Detector.

This study reports on the implementation of Bayesian inference to improve the estimation of remote-depth profiling for low-level radioactive contaminants with a low-resolution NaI(Tl) detector. In particular, we demonstrate that this approach offers results that are more reliable because it provides a mean value with a 95% credible interval by determining the probability distributions of the burial depth and activity of a radioisotope in a single measurement. To evaluate the proposed method, the simulation was compared with experimental measurements. The simulation showed that the proposed method was able to detect the depth of a Cs-137 point source buried below 60 cm in sand, with a 95% credible interval. The experiment also showed that the maximum detectable depths for weakly active 0.94-μCi Cs-137 and 0.69-μCi Co-60 sources buried in sand was 21 cm, providing an improved performance compared to existing methods. In addition, the maximum detectable depths hardly degraded, even with a reduced acquisition time of less than 60 s or with gain-shift effects; therefore, the proposed method is appropriate for the accurate and rapid non-intrusive localization of buried low-level radioactive contaminants during in situ measurement.