The sorption parameters of two heavy metals (i.e. Pb and Cu) in clay soils from Selangor were studied using batch equilibrium test. The test was conducted in two separate systems, i.e. single and mix solutions. The sorption isotherms data from this test were then used to calculate the sorption parameters, i.e. distribution coefficient (Kd) and maximum adsorption capacity (Am). Langmuir sorption equation was used to model the sorption data with the correlation coefficients (r2) higher than 0.6. The study has revealed that different soils have different sorption capacity for different heavy metals. The Kd values are proportional to the sorption capacity of the soils. The sorption of Pb and Cu in single solution is higher than in mix solution, due to the competition for sorption sites among heavy metals in mix solution. The Kd values for Pb in single solution ranging from 36.18-334.48 L/g and for Cu is 9.29-66.19 L/g. In mix solution, the Kd values for Pb and Cu are much smaller, ranging from 23.13-31.79 L/g and 3.95-18.53 L/g respectively. The Am values in single solution for both Pb and Cu are ranging from 0.48-1.09 mg/g dan 0.18-0.70 mg/g respectively. While in mix solution, the values of Am for Pb ranging from 0.20-1.11 mg/g and Cu within 0.18-0.60 mg/g.
This study was carried out at an ultrabasic area, Selaru and Felda Rokan Barat, Kuala Pilah, Negeri Sembilan. Eighteen samples of plant and its substrates were collected for determination of heavy metal contents such as Ni, Co, Cr, Mn and Fe in soils and plants. The plants were separated into different portion such as root, stem and leaf and extracted for their heavy metal content by wet digestion method whereas the soils heavy metal available and resistant content were extracted by sequential extraction. Heavy metals content in soil and plant extract was determined using Flame Atomic Absorption Spectrophotometer. The result showed that total content of heavy metals for Ni, Cr, Co, Mn and Fe was at 84.13 - 740.36 mg/kg, 23.51 - 135.53 mg/kg, 188.23 - 848.92 mg/kg, 245.00 - 545.33 mg/kg and 1176.77 - 1243.90 mg/kg, respectively. Bio-available heavy metals content in soil is at 0.09-6.32 mg/kg for Ni, 0-0.51 mg/kg for Co, 0 mg/kg for Cr, 7.78-21.07 mg/kg for Mn and 2.23-4.47 mg/kg for Fe. Based on BAC, Mn and Fe were detected to have a high concentration in plant parts compared to other heavy metals.
A geotechnical study needs to be carried out to determine the engineering parameters of the rock mass at the project site in executing construction projects such as tunnels, dams, highways and buildings. Design and safety factor of the construction are highly dependent on soil and rock engineering parameters which are usually determined by in-situ test such as Standard Penetration Test (SPT) and seismic tests. The SPT test which normally involves drilling and laboratory works always incur high operating cost, while seismic tests on the other hand are fast, cheap, non-destructive and an easy to operate method for rock mass characterization. The spectral analysis of surface waves (SASW) method is an in situ and non-destructive measurement that is rapid and cost effective. The aims of this study were to determine Rock Quality Designation (RQD) value, excavation classification analysis as well as site characterization by using the SASW method. WinSASW 3.1.3 was used for inversion processing of the SASW data to produce shear wave velocity (Vs) versus depth profiles. The profiles were then analyzed and correlated with rock mass engineering geological parameters such as RQD and site characterization as well as excavation classification of rock mass. Twenty (20) SASW tests were conducted on the granitic rock mass and four (4) SASW tests were conducted on a cut hill slope of metasedimentary rocks. RQD values were computed based on shear wave velocities and ultrasonic velocities of intact (fresh) rock. The differences between RQD obtained from SASW method and those from discontinuity survey were found to be less than 10%. Excavation classification for granitic rock mass at JKR Quarry was empirically determined using both SASW and ultrasonic velocities as well as RQD value of the rock mass. Site characterization for metasedimentary rocks mass at Bukit Tampoi was determined based on shear wave velocities from SASW method.
Addition of chemical binders such as lime and cement improves the strength and stiffness
of fine grained soils. However, the treated soils exhibit brittle stress-strain behaviour.
Inclusion of randomly oriented discrete fibers in the soil-binder mixture changes its brittle
behaviour into ductile behaviour. Most synthetic fibers, however, tend to get entangled
and cannot be easily separated from one another. Therefore, it is difficult to realize soilbinder-
fiber mixtures in which the fibers are distributed uniformly throughout the mass.
This issue has been an impediment in the utilization of the positive modification in the
behaviours of soils and soil-binder mixtures by the fibers. The present study aims to address
the limitations in using fibers as soil reinforcement. Further, it also aims to investigate
the use of synthetic mesh or net elements as an alternative type of soil reinforcement.
The paper presents the experimental study on a fine grained soil. Lime has been chosen
as the binder due to its low cost and the scarcity of fiber reinforced soil studies in which
lime has been used as a binder. The main experimental program is a series of unconfined
compression tests on samples prepared using untreated soil, soil-reinforcement mixture,
soil-lime mixture, and soil-lime-reinforcement mixture. The lime treated samples were
cured up to 120 days at laboratory temperature. The results demonstrate the combinational
effects of lime and discrete reinforcement
elements on the behaviour and mechanical
properties of the soil. The performances of
the fiber and mesh element reinforcements
have also been compared.
An extensive study was conducted to determine the activity concentrations of natural and artificial radionuclides 226Ra, 232Th, 40K, and 137Cs in soil samples of each governate of Jordan. A total of 370 samples have been measured using a high-purity germanium detector. The activity concentration for 226Ra, 232Th, 40K, and 137Cs has mean values of 42 ± 3, 23 ± 3, 309 ± 21, and 3.7 ± 0.9 Bq kg-1, respectively. The highest mean activity concentration for 226Ra was found to be 138 ± 4 Bq kg-1 in the Alkarak governate. In the Ajloun and Jarash governates, the highest mean activity concentration was 35 ± 3 Bq kg-1 for 232Th, and 14.2 ± 1.9 Bq kg-1 for 137Cs, respectively. Geological influence on the activity concentrations was investigated using the one-way analysis of variance (ANOVA) and independent samples. The ANOVA results indicate that there are strong significant differences between the activity concentrations of 232Th, 40K, and 137Cs based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to 226Ra activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg-1, and 0.266, respectively.
This study was carried out on the hilly topographic area in Kundasang, Sabah. This area is known to be extremely prone to landslides that occurred either naturally or by human interference to natural slopes. Aerial photographs interpretation was conducted in order to identify landslide distributions across three assessment years (2012, 2009 and 1984). These datasets were classified into two landslides groups based on their occurrences; natural and artificial. A total of 362 naturally occurring landslides were identified and another 133 are artificial slope landslides. Physical parameters which include lithology, slope angle, slope aspect and soil series were analyzed with each landslide group to examine the different influence of these parameters on each of the group. From the analysis, the landslide density for the natural landslide group shows that more than 35° slope angle and slope aspect facing east and southwest are prone to landslides. In terms of geological materials, high landslide density is recorded in the phyllite, shale, siltstone and sandstone lithologies group and the Pinosuk, Kepayan and Trusmadi soil series. In contrast, for the artificial
slope landslide, high landslide density is observed in the 25°-35° slope angle and similar density in every slope aspect classes. The geological materials however have similar landslide density across their factors’ classes. The landslide density technique was also used to generate the landslide susceptibility maps for both landslide conditions. Validation of the maps shows acceptable accuracy of 71% and 74%, respectively, for both natural and artificial slope landslide susceptibility maps and this shows that these maps can be used for future land use planning.
This paper investigates the compressibility characteristics of compacted clay treated with cement, peat ash and silica
sand. For this purpose, one dimensional consolidation tests were conducted to determine the soil consolidation properties.
The test specimens were trimmed from the compaction test specimen. The 1D consolidation test specimen was subjected
to the normal pressures of 2.5, 5, 10, 20, 40, 80 and 160 kPa in sequence on the test specimen which was saturated with
distilled water. At the end of the loading period of 80 kPa, the vertical load was removed and the specimen was allowed
to expand for 24 h for the purpose of evaluating of its swelling behavior. The results showed that void ratio of the soil
specimens decreased with increasing effective normal pressure. The laboratory investigation clearly demonstrates that,
settlement is as the compression of a soil specimen due to vertical loading applied at the top surface of the 1D consolidation
test specimen. It was concluded that, the compression settlement of the stabilized soil with the binder composition of
18% cement, 2% peat ash and 5% silica sand improved by almost 1.3-fold. A notable discovery is the suitability of the
stabilized soil for road embankment and low lying marginal area for foundation works; also solving the environmental
problems in relation to peaty ground. However, sufficient laboratory and field testing are required.
Ground improvement using artificial crust composite foundation, consisting of stabilization of soft clay and composite foundation, is an effective technique for the treatment of deep soft soil layers under infrastructure embankments. In this study, the load responses and settlement performance of this improvement technique were investigated using two centrifuge model tests to compare the variations of the vertical deformation, pore water pressure, axial force of the piles and tensile stress at the bottom of the artificial crust in the crust composite foundation with those in pile-supported embankment. The results of centrifuge model tests showed that the load responses and settlement performance of artificial crust composite foundation was different from the pile-supported embankment, which displayed mainly that the final middle settlement of crust composite foundation can be reduced by about 15% compared with those of pile-supported embankment with the same length of pile and construction cost. The deformation of the crust with the characteristics of the plate was found based on the change of the tensile stress. Additionally, the excess pore water pressure in the crust composite foundation was lower owing to the stress diffusion effect of the crust during the loading period and the dissipation rate of excess pore water pressure was slower due to lower permeability of the crust at the same loading period. Eventually, the axial force of the middle piles was reduced. At the same time, the boundary stress was functioned with the crust, the axial force of the side piles was improved. The comparison of measured and calculated results was carried out using the stress reduction ratio, the result shows that the bearing capacity of the subsoil in the crust composite was improved.
Litter decomposition is vital for carbon and nutrient turnover in terrestrial ecosystems, and this process has now
been thoroughly demonstrated to be regulated by various mechanisms. The total environment has been continuously
changing in recent decades, especially in high-latitude regions; these alterations, however, profoundly contribute to the
decomposition process, but a comprehensive recognition has not available. Here we reviewed the empirical observations
and current knowledge regarding how hydrological leaching and freeze-thaw events modulate early decomposition of
plant litter. Leaching contributes a considerable percentage of mass loss and carbon and nutrient release in early stage of
decomposition, but the magnitudes are different between species levels depending on the chemical traits. Frequent freezing
and thawing events could positively influence decomposition rate in cold biomes but also hamper soil decomposer and
there is no general and predictable pattern has been emerged. Further experiments should be manipulated to estimate
how the altered freezing and thawing effect on carbon and nutrient release from plant litter to better understanding the
changing environment on litter decomposition.
Over the years, sedimentation has posed a great danger to the storage capacity of hydropower reservoirs. Good understanding of the transport system and hydrological processes in the dam is very crucial to its sustainability. Under optimal functionality, the Shiroro dam in Northern Nigeria can generate ∼600 MW, which is ideally sufficient to power about 404,000 household. Unfortunately, there have not been reliable monitoring measures to assess yield in the upstream, where sediments are sourced into the dam. In this study, we applied the Soil and Water Assessment Tool (SWAT) to predict the hydrological processes, the sediment transport mechanism and sediment yield between 1990 and 2018 in Kaduna watershed (32,124 km2) located upstream of the dam. The model was calibrated and validated using observed flow and suspended sediment concentration (SSC) data. Performance evaluation of the model was achieved statistically using Nash-Sutcliffe (NS), coefficient of determination (r2) and percentage of observed data (p-factor). SWAT model evaluation using NS (0.71), r2 (0.80) and p-factors of 0.86 suggests that the model performed satisfactorily for streamflow and sediment yield predictions. The model identified the threshold depth of water (GWQMN.gw) and base flow (ALPHA_BF.gw) as the most sensitive parameters for streamflow and sediment yield estimation in the watershed. Our finding showed that an estimated suspended sediment yield of about 84.1 t/ha/yr was deposited within the period under study. Basins 67, 71 and 62 have erosion prone area with the highest sediment values of 79.4, 75.1 and 73.8 t/h respectively. Best management practice is highly recommended for the dam sustainability, because of the proximity of erosion-prone basins to the dam.
Cypermethrin is a pyrethroid insecticide commonly used to control bagworm infestation in oil palm plantations. It is applied through spraying onto the leaves where the bagworms reside. This article reports the fate of cypermethrin used in a Malaysian oil palm plantation during a typical dry season through the analysis of cypermethrin residue in environmental and palm oil samples collected from a supervised field trial. Residues of cypermethrin were not detected in the soil samples collected at different depths, water samples collected at different points in the experimental plots, and oil samples extracted from fresh fruit bunches (FFB) harvested from each plot for both single and double dosages of treatment throughout the study interval. Analysis of leaf samples, however, revealed that cypermethrin residue was detected for both pesticide treatments up to day 2 after cypermethrin application.
Regular optimization techniques have been widely used in landslide-related problems. This paper outlines two novel optimizations of artificial neural network (ANN) using grey wolf optimization (GWO) and biogeography-based optimization (BBO) metaheuristic algorithms in the Ardabil province, Iran. To this end, these algorithms are synthesized with a multi-layer perceptron (MLP) neural network for optimizing its computational parameters. The used spatial database consists of fourteen landslide conditioning factors, namely elevation, slope aspect, land use, plan curvature, profile curvature, soil type, distance to river, distance to road, distance to fault, rainfall, slope degree, stream power index (SPI), topographic wetness index (TWI) and lithology. 70% of the identified landslides are randomly selected to train the proposed models and the remaining 30% is used to evaluate the accuracy of them. Also, the frequency ratio theory is used to analyze the spatial interaction between the landslide and conditioning factors. Obtained values of area under the receiver operating characteristic curve, as well as mean square error and mean absolute error showed that both GWO and BBO hybrid algorithms could efficiently improve the learning capability of the MLP. Besides, the BBO-based ensemble surpasses other implemented models.
Studies reveal that climate change (CC) has higher negative impacts on agricultural production than positive impacts. Therefore, this article attempts to explore the impacts of CC on oil palm production in Malaysia and provides mitigation and adaptation strategies towards reducing such impacts. The multiple regression analysis is applied to assess the impacts of CC on oil palm production by using time series data in the period of 1980 to 2010. A negative and significant relationship is found between annual average temperature and oil palm production. If temperature rises by 1 °C, 2 °C, 3 °C, and 4 °C, production of oil palm can decrease from a range of 10 to 41%. This article has also found a negative impact of sea level rise (SLR) on oil palm production. Findings reveal that if areas under oil palm production decrease by 2%, 4%, and 8% due to SLR of 0.5, 1, and 2 m, oil palm production can decrease by 1.98%, 3.96%, and 7.92%, respectively, indicating that CC has a significant impact on the reduction of oil palm production in Malaysia, ultimately affecting the sustainability of oil palm sector in Malaysia. Finally, this study suggests to practice appropriate mitigation and adaptation strategies, including promotion and development of climate resilient varieties, soil and water conservation, afforestation, insurance and other risk transfer mechanisms, emission reduction technology, protection of coastal flooding for reducing the impacts of CC on oil palm production.
Rice ingestion is one of the major pathways for heavy metal bioaccumulation in human. This study aimed to measure the heavy metal content of paddy soils and its bioavailability in paddy grain in order to assess the health risk. In total, 10 rice samples (50 g each) of paddy plants were harvested from the Selangor and Terengganu areas of Malaysia to assess the bioavailability of heavy metal (As, Cd, Cu, Cr, and Pb) using the in vitro digestion model of Rijksinstituut voor Volksgezondheid en Milieu. The bioavailability of heavy metal concentrations in rice samples were analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The findings showed the bioavailability of heavy metal concentrations was decreased in the order Cr > Cu > Pb > As > Cd. Chromium was found to be the most abundant bioavailable heavy metal in cooked rice, which was the result of its high content in paddy soil. Hazard Quotient values for the bioavailability of the heavy metal studied were less than one indicating no non-carcinogenic health risks for adults and children. Meanwhile, the total Lifetime Cancer Risk exceeded the acceptable value showing a potential of carcinogenic health risk for both adults and children. The application of in vitro digestion model in assessing bioavailability of heavy metal produces a more realistic estimation of human health risks exposure. However, a regular monitoring of pollution in Selangor and Terengganu areas is crucial since the exposure of heavy metals through rice consumption poses the potential non-carcinogenic and carcinogenic health risk to the local residents.
Ganoderma boninense is a soil-borne Basidiomycete pathogenic fungus that eminent as the key causal of devastating disease in oil palm, named basal stem rot. Being a threat to sustainable palm oil production, it is essential to comprehend the fundamental view of this fungus. However, there is gap of information due to its limited number of genome sequence that is available for this pathogenic fungus. This implies the hitches in performing biological research to unravel the mechanism underlying the pathogen attack in oil palm. Therefore, here we report a dataset of draft genome of G. boninense that was sequenced using Illumina Hiseq 2000. The raw reads were deposited into NCBI database (SRX7136614 and SRX7136615) and can be accessed via Bioproject accession number PRJNA503786.
A low-cost, low-power, and low data-rate solution is proposed to fulfill the requirements of information monitoring for actual large-scale agricultural farms. A small-scale farm can be easily managed. By contrast, a large farm will require automating equipment that contributes to crop production. Sensor based soil properties measurement plays an integral role in designing a fully automated agricultural farm, also provides more satisfactory results than any manual method. The existing information monitoring solutions are inefficient in terms of higher deployment cost and limited communication range to adapt the need of large-scale agriculture farms. A serial based low-power, long-range, and low-cost communication module is proposed to confront the challenges of monitoring information over long distances. In the proposed system, a tree-based communication mechanism is deployed to extend the communication range by adding intermediate nodes. Each sensor node consists of a solar panel, a rechargeable cell, a microcontroller, a moisture sensor, and a communication unit. Each node is capable to work as a sensor node and router node for network traffic. Minimized data logs from the central node are sent daily to the cloud for future analytics purpose. After conducting a detailed experiment in open sight, the communication distance measured 250 m between two points and increased to 750 m by adding two intermediate nodes. The minimum working current of each node was 2 mA, and the packet loss rate was approximately 2-5% on different packet sizes of the entire network. Results show that the proposed approach can be used as a reference model to meet the requirements for soil measurement, transmission, and storage in a large-scale agricultural farm.
Phosphate solubilizing bacteria (PSBs) shows high potential to be used for lead passivation in sediments due to the abilities of releasing phosphate and the subsequent formation of insoluble Pb-phosphate compounds. In this research, microbial capsules implemented with sodium alginate and CaCl2, containing Leclercia adecarboxylata L15 (a lead resistant PSB) and Ca3(PO4)2, were developed and the performance on lead passivation under different conditions was examined. The optimal concentrations of sodium alginate and CaCl2 for formulating the capsules were determined to be 0.3% and 10%, respectively. The removal efficiency of Pb2+ by capsules containing L15 and Ca3(PO4)2 was up to 98% with a capsule dosage of 2%, initial Pb2+ concentration of 1mM and pH of 3.0, which was better than that of free L15 (18%) and capsules containing only L15 (34%). Lead was immobilized via the formation of Pb5(PO4)3Cl on the surface and Pb3(PO4)2 in the interior of the capsules. The simulated sediment remediation experiments showed that the acid soluble fraction of lead reduced from 28% to 14% and transformed into more stable fractions after 10 days. The experiment results indicated that PSBs capsules coupled with phosphate materials have a great promise for application in remediation of lead contaminated sediments.
Ethylenediaminetetraacetic acid (EDTA) can serve as a washing agent in the remediation of low-permeability layers contaminated by heavy metals (HMs). Therefore, batch adsorption experiments, where pure quartz (SM1) and mineral mixtures (SM2) were used as typical soil minerals (SMs) in low-permeability layers, were implemented to explore the effects of different EDTA concentrations, pH, and exogenous chemicals on the HM-SM-EDTA adsorption system. As the EDTA concentration increased, it gradually cut down the maximum Cd adsorption capacities of SM1 and SM2 from approximately 135 to 55 mg/kg and 2660 to 1453 mg/kg; and the maximum Pb adsorption capacities of SM1 and SM2 were reduced from 660 to 306 mg/kg and 19,677 to 19,262 mg/kg, respectively. When the initial mole ratio (MR = moles of HM ions/sum of moles of HM ions and EDTA) was closer to 0.5, the effect of EDTA was more effective. Additionally, EDTA worked well at pH below 7.0 and 4.0 for Cd and Pb, respectively. Low-molecular-weight organic acids (LMWOAs) affected the system mainly by bridging, complexation, adsorption site competition, and reductive dissolution. Cu2+, Fe2+ ions could significantly increase the Cd and Pb adsorption onto SM2. Notably, there were characteristic changes in mineral particles, including attachment of EDTA and microparticles, agglomeration, connection, and smoother surfaces, making the specific surface area (SSA) decrease from 16.73 to 12.59 m2/g. All findings indicated that EDTA could effectively and economically reduce the HM adsorption capacity of SMs at the reasonable MR value, contact time, and pH; EDTA reduced the HM adsorption capacity of SMs not only by complexation with HM ions but also by decreasing SSA and blocking active sites. Hence, the acquired insight from the presented study can help to promote the remediation of contaminated low-permeability layers in groundwater.
The durability of natural and treated clay soil stabilized with lime and alkaline activation (AA) affected by environmental factors (hot and humid) was determined in this study. Investigation and evaluation on the strength of the soil, moisture content, and volume change of the specimen were determined at each curing period (7, 28, and 90 days) based on the weather conditions. An unconfined compressive strength (UCS) of the specimen at three different wetting/drying cycles (one, three, and five cycles) was determined. The findings show that the strength of the treated specimens fluctuated with increment and decrement strength (one and three cycles) in the range of 1.41 to 1.88 MPa (lime) and 2.64 to 8.29 MPa (AA), while for five cycles with a curing period of 90 days the decrement was in the range of 1.62 to 1.25 MPa and 6.06 to 5.89 MPa for lime and AA, respectively. The decrement percentage for treated samples that were subjected to five cycles of wetting and drying in 90 days was found to be 20.38% (lime) and 38.64% (AA), respectively. Therefore, it can be summarized that wetting/drying cycles have a significant influence on the durability, strength, and the volume changes of the specimens.
Bauxite mining in Kuantan district of Pahang has raised health concerns of communities residing near the mining areas. Bauxite mining and transportation activities have contributed a lot to the pollution of environment. There is a fear among the residents of the areas that whether the soil is free from naturally occurring radioactive substances or not. Therefore, the objective of this study was to detect the presence of natural radioactive elements in the soil of bauxite mining field at Bukit Goh, Kuantan.