The cellulose microfibers (CMF) from water hyacinth (WH) fiber as a filler in sago starch (SS) biocomposites was investigated. The CMF was isolated by pulping, bleaching and acid hydrolysis methods. The addition of CMF in sago matrix was varied i.e. 0, 5, 10, 15 and 20 wt%. Biocomposites were made by using solution casting and glycerol as a plasticizer. The biocomposites were also determined by tensile test, FTIR, X-Ray, thermogravimetric, SEM, and soil burial tests. The results show that the SS15CMF sample has the highest tensile strength of 10.23 MPa than those other samples. Scanning Electron Microscope (SEM) images show that the strong interaction was formed between CMF WH and matrix. Fourier Transform Infra-red (FTIR) indicated that the functional group of biocomposites was a hydrophilic cluster. The addition of CMF WH in sago starch biocomposites lead to the moisture barrier, crystallinity, and thermal stability increased; it is due to the pure sago starch film was more rapidly degraded than its biocomposites.
In this study geogenic radon potential (GRP) mapping was carried out on the bases of field radon in soil gas concentration and soil gas permeability measurements by considering the corresponding geological formations. The spatial pattern of soil gas radon concentration, soil permeability, and GRP and the relationship between geological formations and these parameters was studied by performing detailed spatial analysis. The radon activity concentration in soil gas ranged from 0.11 to 434.5 kBq m-3 with a mean of 18.96 kBq m-3, and a standard deviation was 55.38 kBq m-3. The soil gas permeability ranged from 5.2×10-14 to 5.2×10-12 m2, with a mean of 5.65×10-13 m2. The GRP values were computed from the 222Rn activity concentration and soil gas permeability data. The range of GRP values was from 0.04 to 154.08. Locations on igneous granite rock geology were characterized by higher soil radon gas activity and higher GRP, making them radon-prone areas according to international standards. The other study locations fall between the low to medium risk, except for areas with high soil permeability, which are not internationally classified as radon prone. A GRP map was created displaying radon-prone areas for the study location using Kriging/Cokriging, based on in situ and predicted measured values. The GRP map assists in human health risk assessment and risk reduction since it indicates the potential of the source of radon and can serve as a vital tool for radon combat planning.
Soil ecosystems are home to a diverse range of microorganisms, but they are only partially understood because no single-cell sequencing or whole-community sequencing provides a complete picture of these complex communities. Using one of such metagenomics approaches, we succeeded in monitoring the microbial diversity and stress-response gene in the soil samples. This study aims to test whether known differences in taxonomic diversity and composition are reflected in functional gene profiles by implementing whole gene sequencing (WGS) metagenomic analysis of geographically dispersed soils from two distinct pristine forests. The study was commenced by sequencing three rainforest soil samples and three peat swamp soil samples. Soil richness effects were assessed by exploring the changes in specific functional gene abundances to elucidate physiological constraints acting on different soil systems and identify variance in functional pathways relevant to soil biogeochemical cycling. Proteobacteria shows abundances of microbial diversity for 52.15% in Royal Belum Reserved Forest and 48.28% in Raja Musa; 177 out of 1,391,841 and 449 out of 3,586,577 protein coding represent acidic stress-response genes for Royal Belum and Raja Musa, respectively. Raja Musa indicates pH 2.5, which is extremely acidic. The analysis of the taxonomic community showed that Royal Belum soils are dominated by bacteria (98% in Sungai Kooi (SK), 98% in Sungai Papan (SP), and 98% in Sungai Ruok (SR), Archaea (0.9% in SK, 0.9% in SP, and 1% in SR), and the remaining were classed under Eukaryota and viruses. Likewise, the soils of Raja Muda Musa are also dominated by bacteria (95% in Raja Musa 1 (RM1), 98% in Raja Musa 2 (RM2), and 96% in Raja Musa 3 (RM3)), followed by Archaea (4% in RM1, 1% in RM2, and 3% in RM3), and the remaining were classed under Eukaryota and viruses. This study revealed that RBFR (Royal Belum Foresr Reserve) and RMFR (Raja Musa Forest Reserve) metagenomes contained abundant stress-related genes assigned to various stress-response pathways, many of which did not show any difference among samples from both sites. Our findings indicate that the structure and functional potential of the microbial community will be altered by future environmental potential as the first glimpse of both the taxonomic and functional composition of soil microbial communities.
Vast amounts of plastic waste are causing serious environmental issues and urge to develop of new remediation methods. The aim of the study is to determine the role of inorganic (nitric acid), organic (starch addition), and biological (Pseudomonas aeruginosa) soil amendments on the degradation of Polyethylene (PE) and phytotoxic assessment for the growth of lettuce plant. The PE-degrading bacteria were isolated from the plastic-contaminated soil. The strain was identified as Pseudomonas aeruginosa (OP007126) and showed the highest degradation percentage for PE. PE was pre-treated with nitric acid as well as starch and incubated in the soil, whereas P. aeruginosa was also inoculated in PE-contaminated soils. Different combinations were also tested. FTIR analysis and weight reduction showed that though nitric acid was efficient in degradation, the combined application of starch and bacteria also showed effective degradation of PE. Phytotoxicity was assessed using morphological, physiological, and biochemical parameters of plant. Untreated PE significantly affected plants' physiology, resulting in a 45% reduction in leaf chlorophyll and a 40% reduction in relative water content. It also had adverse effects on the biochemical parameters of lettuce. Bacterial inoculation and starch treatment mitigated the harmful impact of stress and improved plants' growth as well as physiological and biochemical parameters; however, the nitric treatment proved phytotoxic. The observed results revealed that bacteria and starch could be effectively used for the degradation of pre-treated PE.
This is the first attempt in the world to depict the vertical distribution of radionuclides in the soil samples along several heights (900 feet, 1550 feet, and 1650 feet) of Marayon Tong hill in the Chittagong Hill Tracts, Bandarban by HPGe gamma-ray spectrometry. The average activity concentrations of 232Th, 226Ra, and 40K were found to be 37.15 ± 3.76 Bqkg-1, 19.69 ± 2.15 Bqkg-1, and 347.82 ± 24.50 Bqkg-1, respectively, where in most cases, 232Th exceeded the world average value of 30 Bqkg-1. According to soil characterization, soils ranged from slightly acidic to moderately acidic, with low soluble salts. The radium equivalent activity, outdoor and indoor absorbed dose rate, external and internal hazard indices, external and internal effective dose rates, gamma level index, and excess lifetime cancer risk were evaluated and found to be below the recommended or world average values; but a measurable activity of 137Cs was found at soils collected from ground level and at an altitude of 1550 feet, which possibly arises from the nuclear fallout. The evaluation of cumulative radiation doses to the inhabitants via periodic measurement is recommended due to the elevated levels of 232Th.This pioneering work in mapping the vertical distribution of naturally occurring radioactive materials (NORMs) can be an essential factual baseline data for the scientific community that may be used to evaluate the variation in NORMs in the future, especially after the commissioning of the Rooppur Nuclear Power Plant in Bangladesh in 2024.
The soil organic carbon accumulation in soda saline-alkaline soil and the humus composition changes with application of aluminum sulfate and rice straw were investigated by the controlled simulative experiments in laboratory. For evaluating the amelioration effect, organic carbon content and humus composition in soda saline-alkaline soil were investigated with different application amounts of rice straw and aluminum sulfate. Potassium dichromate oxidation titration (exogenous heat) method and Kumada method were used to analyze the contents of organic carbon and humus composition, respectively. The transformation of soil organic matter in the saline-alkali soil during the amelioration has been clarified in this paper. The results demonstrated that the contents of soil organic carbon were significantly increased (13-92%) with different application amounts of rice straw and aluminum sulfate. The contents of free fraction and combined fraction of humus and their compositions (humic acid and fulvic acid) were increased with different application amounts of rice straw. The free fraction of humus was increased more dramatically. Due to aluminum sulfate application, free fraction of humus and humic acid (HA) was transformed to combined fraction partially. Free HA was changed to be P type with rice straw application. With aluminum sulfate application, free form of HA was changed from type P to type Rp. For rice straw application, combined HA only was transferred within the area of type A. Aluminum sulfate addition had no significant effect on the type of combined form of HA. With the same amount of rice straw application, the contents of soil organic carbon were increased by increasing the amount of aluminum sulfate application. Both rice straw and aluminum sulfate applications could reduce the humification degree of free and combined fraction of HA. According to the types of HA, it could be concluded that humus became younger and renewed due to the application of rice straw and aluminum sulfate.
Greenhouse experiments were carried out to determine the phytotoxic effects on the plant Ludwigia octovalvis in order to assess its applicability for phytoremediation gasoline-contaminated soils. Using plants to degrade hydrocarbons is a challenging task. In this study, different spiked concentrations of hydrocarbons in soil (1, 2, and 3 g/kg) were tested. The results showed that the mean efficiency of total petroleum hydrocarbon (TPH) removal over a 72-day culture period was rather high. The maximum removal of 79.8 % occurred for the 2 g/kg concentration, while the removal rate by the corresponding unplanted controls was only (48.6 %). The impact of gasoline on plants included visual symptoms of stress, yellowing, growth reduction, and perturbations in the developmental parameters. The dry weight and wet weight of the plant slightly increased upon exposure to gasoline until day 42. Scanning electron microscopy (SEM) indicated change to the root and stem structure in plant tissue due to the direct attachment with gasoline contaminated compared to the control sample. The population of living microorganisms in the contaminated soil was found to be able to adapt to different gasoline concentrations. The results showed that L. octovalvis and rhizobacteria in gasoline-contaminated soil have the potential to degrade organic pollutants.
A novel kinetic model has been developed to explain the degradation of total petroleum hydrocarbons. Microbiome engineered biochar amendment may result in a synergistic impact on degradation of total petroleum hydrocarbons (TPHs). Therefore, the present study analyzed the potential of hydrocarbon-degrading bacteria A designated as Aeromonas hydrophila YL17 and B as Shewanella putrefaciens Pdp11 morphological characterized as rod shaped, anaerobic and gram-negative immobilized on biochar, and the degradation efficiency was measured by gravimetric analysis and gas chromatography-mass spectrometry (GC-MS). Whole genome sequencing of both strains revealed the existence of genes responsible for hydrocarbon degradation. In 60 days remediation setup, the treatment consisting of immobilization of both strains on biochar proved more efficient with less half-life and better biodegradation potentials compared to biochar without strains for decreasing the content of TPHs and n-alkanes (C12-C18). Enzymatic content and microbiological respiration showed that biochar acted as a soil fertilizer and carbon reservoir and enhanced microbial activities. The removal efficiency of hydrocarbons was found to be a maximum of 67% in soil samples treated with biochar immobilized with both strains (A + B), followed by biochar immobilized with strain B 34%, biochar immobilized with strain A 29% and with biochar 24%, respectively. A 39%, 36%, and 41% increase was observed in fluorescein diacetate (FDA) hydrolysis, polyphenol oxidase and dehydrogenase activities in immobilized biochar with both strains as compared to control and individual treatment of biochar and strains. An increase of 35% was observed in the respiration rate with the immobilization of both strains on biochar. While a maximum colony forming unit (CFU/g) was found 9.25 with immobilization of both strains on biochar at 40 days of remediation. The degradation efficiency was due to synergistic effect of both biochar and bacteria based amendment on the soil enzymatic activity and microbial respiration.
A diesel-degrading bacterium was isolated from a diesel-contaminated site in Selangor, Malaysia. The isolate was tentatively identified as Acinetobacter sp. strain DRY12 based on partial 16S rDNA molecular phylogeny and Biolog GN microplate panels and Microlog database. Optimum growth occurred from 3 to 5% diesel and the strain was able to tolerate as high as 8% diesel. The optimal pH that supported growth of the bacterium was between pH 7.5 to 8.0. The isolate exhibited optimal growth in between 30 and 35 degrees C. The best nitrogen source was potassium nitrate (between 0.6 and 0.9% (w/v)) followed by ammonium chloride, sodium nitrite and ammonium sulphate in descending order. An almost complete removal of diesel components was seen from the reduction in hydrocarbon peaks observed using Solid Phase Microextraction Gas Chromatography analysis after 10 days of incubation. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibiting growth with a correlation coefficient value of 0.97. The maximum growth rate- micromax was 0.039 hr(-1) while the saturation constant or half velocity constant Ks and inhibition constant Ki, were 0.387% and 4.46%, respectively. MATH assays showed that 75% of the bacterium was found in the hexadecane phase indicating that the bacterium was hydrophobic. The characteristics of this bacterium make it useful for bioremediation works in the Tropics.
Repeated applications of animal manure as fertilizer are normal agricultural practices that may release veterinary antibiotics and hormones into the environment from treated animals. Broiler manure samples and their respective manure-amended agricultural soil samples were collected in selected locations in the states of Selangor, Negeri Sembilan and Melaka in Malaysia to identify and quantify veterinary antibiotic and hormone residues in the environment. The samples were analyzed using ultrasonic extraction followed by solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The broiler manure samples were found to be contaminated with at least six target analytes, namely, doxycycline, enrofloxacin, flumequine, norfloxacin, trimethoprim and tylosin. These analytes were detected in broiler manure samples with maximum concentrations reaching up to 78,516 μg kg(-1) dry weight (DW) (doxycycline). For manure-amended agricultural soil samples, doxycycline and enrofloxacin residues were detected in every soil sample. The maximum concentration of antibiotic detected in soil was 1331 μg kg(-1) DW (flumequine). The occurrence of antibiotics and hormones in animal manure at high concentration poses a risk of contaminating agricultural soil via fertilization with animal manure. Some physico-chemical parameters such as pH, total organic carbon (TOC) and metal content played a considerable role in the fate of the target veterinary antibiotics and progesterone in the environment. It was suggested that these parameters can affect the adsorption of pharmaceuticals to solid environmental matrices.
The degradation behavior of veterinary antibiotics in soil is commonly studied using the following methods of adding antibiotics to the soil: (i) adding manure collected from animals fed with a diet containing antibiotics, (ii) adding antibiotic-free animal manure spiked with antibiotics and (iii) directly adding antibiotics. No research simultaneously comparing different antibiotic addition methods was found. Oxytetracycline (OTC) was used as a model antibiotic to compare the effect of the three commonly used antibiotic addition methods on OTC degradation behavior in soil. The three treatment methods have similar trends, though OTC degradation half-lives show the following significant differences (P<0.05): manure from swine fed OTC (treatment A)soil. Because the main entry route for veterinary antibiotics into soil is via the manure of animals given with antibiotics, the most appropriate method to study the degradation and ecotoxicity of antibiotic residues in soil may be to use manure from animals that are given a particular antibiotic, rather than by adding it directly to the soil.
The influence of temperature, moisture and organic matter on the persistence of cyfluthrin was determined using three types of Malaysian soils, namely clay, clay loam and sandy clay loam obtained from a tomato farm in Cameron Highlands, Pahang. The persistence of cyfluthrin was observed in the laboratory at two temperature levels of 25 and 35 degreeC and field water capacity of 30 and 80%. Treated soil samples were incubated in a growth chamber for 1, 2, 3, 5, 7, 10, 14, 21 and 28 days. The results from the incubation studies showed that temperature and organic matter content significantly reduced the half-life (t1/2) values of cyfluthrin in the three soil types, but moisture content had very little effect. It was observed that cyfluthrin persisted longer at lower temperature and moisture content and higher organic matter content in all the three soil types. The present study demonstrated that under the tropical conditions of Malaysia, cyfluthrin dissipated rapidly in soils compared to its dissipation in soils of temperate regions, evidently due to high temperature.
In Malaysia, large amounts of organic materials, which lead to disposal problems, are generated from agricultural residues especially from palm oil industries. Increasing landfill costs and regulations, which limit many types of waste accepted at landfills, have increased the interest in composting as a component of waste management. The objectives of this study were to characterize compost feedstock properties of common organic waste materials available in Malaysia. Thus, a ratio modelling of matching ingredients for empty fruit bunches (EFBs) co-composting using different organic materials in Malaysia was done. Organic waste materials with a C/N ratio of < 30 can be applied as a nitrogen source in EFB co-composting. The outcome of this study suggested that the percentage of EFB ranged between 50% and 60%, which is considered as the ideal mixing ratio in EFB co-composting. Conclusively, EFB can be utilized in composting if appropriate feedstock in term of physical and chemical characteristics is coordinated in the co-composting process.
Effects of laterite cover soil with different characteristics on survival of buried eggs, third instar larvae, and pupae of Musca domestica (L.) were studied experimentally. Soil treatments were loose dry soil, loose wet soil, compacted dry soil, and compacted wet soil (CWS). Eggs, third instar larvae, and pupae were buried under 30 cm of the different soil treatments and placed under field conditions until adults emerged. Rearing medium was provided for eggs and larvae, and control treatments of all stages were unburied immatures placed on soil surface. Egg and pupal survival to adult were significantly affected by the cover soil treatments, but third instars were more resilient. Wet soil treatments (loose wet soil and CWS) resulted in significantly reduced pupal survival, but increased survival of eggs. However, CWS significantly reduced adult emergence from buried eggs. Though emergence of house flies buried as eggs was significantly reduced, some were able to hatch and emerging first instar larvae developed to pupation. Although cover soil does not completely prevent fly emergence, it did limit development and emergence of buried house flies.
This study aims to investigate the impacts of ethyl lactate (EL) based Fenton treatment on soil quality for polycyclic aromatic hydrocarbons (PAHs)-contaminated soils. Accumulation of oxygenated-polycyclic aromatic hydrocarbons (oxy-PAHs) was observed, but quantitative measurement on the most abundant compound 9,10-anthraquinone (ATQ) showed lower accumulation of the compound than that reported for ethanol (ET) based Fenton treatment. In general, as compared to conventional water (CW) based Fenton treatment, the EL based Fenton treatment exerted either a lower or higher negative impact on soil physicochemical properties depending on the property type and shared the main disadvantage of reduced soil pH. For revegetation, EL based Fenton treatment was most appropriately adopted for soil with native pH >/~ 6.2 in order to obtain a final soil pH >/~ 4.9 subject to the soil buffering capacity.
Methane (CH₄) emissions and oxidation were measured at the Air Hitam sanitary landfill in Malaysia and were modeled using the Intergovernmental Panel on Climate Change waste model to estimate the CH₄ generation rate constant, k. The emissions were measured at several locations using a fabricated static flux chamber. A combination of gas concentrations in soil profiles and surface CH₄ and carbon dioxide (CO₂) emissions at four monitoring locations were used to estimate the CH₄ oxidation capacity. The temporal variations in CH₄ and CO₂ emissions were also investigated in this study. Geospatial means using point kriging and inverse distance weight (IDW), as well as arithmetic and geometric means, were used to estimate total CH₄ emissions. The point kriging, IDW, and arithmetic means were almost identical and were two times higher than the geometric mean. The CH₄ emission geospatial means estimated using the kriging and IDW methods were 30.81 and 30.49 gm(−2) day(−1), respectively. The total CH₄ emissions from the studied area were 53.8 kg day(−1). The mean of the CH₄ oxidation capacity was 27.5 %. The estimated value of k is 0.138 year(−1). Special consideration must be given to the CH₄ oxidation in the wet tropical climate for enhancing CH₄ emission reduction.
Methane (CH₄) is one of the most relevant greenhouse gases and it has a global warming potential 25 times greater than that of carbon dioxide (CO₂), risking human health and the environment. Microbial CH₄ oxidation in landfill cover soils may constitute a means of controlling CH₄ emissions. The study was intended to quantify CH₄ and CO₂ emissions rates at the Sungai Sedu open dumping landfill during the dry season, characterize their spatial and temporal variations, and measure the CH₄ oxidation associated with the landfill cover soil using a homemade static flux chamber. Concentrations of the gases were analyzed by a Micro-GC CP-4900. Two methods, kriging values and inverse distance weighting (IDW), were found almost identical. The findings of the proposed method show that the ratio of CH₄ to CO₂ emissions was 25.4 %, indicating higher CO₂ emissions than CH₄ emissions. Also, the average CH₄ oxidation in the landfill cover soil was 52.5 %. The CH₄ and CO₂ emissions did not show fixed-pattern temporal variation based on daytime measurements. Statistically, a negative relationship was found between CH₄ emissions and oxidation (R(2) = 0.46). It can be concluded that the variation in the CH₄ oxidation was mainly attributed to the properties of the landfill cover soil.
This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.
In this paper, an attempt has been made to assess, prognosis and observe dynamism of soil erosion by universal soil loss equation (USLE) method at Penang Island, Malaysia. Multi-source (map-, space- and ground-based) datasets were used to obtain both static and dynamic factors of USLE, and an integrated analysis was carried out in raster format of GIS. A landslide location map was generated on the basis of image elements interpretation from aerial photos, satellite data and field observations and was used to validate soil erosion intensity in the study area. Further, a statistical-based frequency ratio analysis was carried out in the study area for correlation purposes. The results of the statistical correlation showed a satisfactory agreement between the prepared USLE-based soil erosion map and landslide events/locations, and are directly proportional to each other. Prognosis analysis on soil erosion helps the user agencies/decision makers to design proper conservation planning program to reduce soil erosion. Temporal statistics on soil erosion in these dynamic and rapid developments in Penang Island indicate the co-existence and balance of ecosystem.
This work focuses on the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil using modified Fenton (MF) treatment coupled with a novel chelating agent (CA), a more effective technique among currently available technologies. The performance of MF treatment to promote PAH oxidation in artificially contaminated soil was investigated in a packed column with a hydrogen peroxide (H(2)O(2)) delivery system simulating in-situ soil flushing which is more representative of field conditions. The effectiveness of process parameters H(2)O(2)/soil, Fe(3+)/soil, CA/soil weight ratios and reaction time were studied using a 2(4) three level factorial design experiments. An optimised operating condition of the MF treatment was observed at H(2)O(2)/soil 0.05, Fe(3+)/soil 0.025, CA/soil 0.04 and 3h reaction time with 79.42% and 68.08% PAH removals attainable for the upper and lower parts of the soil column respectively. The effects of natural attenuation and biostimulation process as post-treatment in the remediation of the PAH-contaminated soil were also studied. In all cases, 3-aromatic ring PAH (phenanthrene) was more readily degraded than 4-aromatic ring PAH (fluoranthene) regardless of the bioremediation approach. The results revealed that both natural attenuation and biostimulation could offer remarkable enhancement of up to 6.34% and 9.38% in PAH removals respectively after 8 weeks of incubation period. Overall, the results demonstrated that combined inorganic CA-enhanced MF treatment and bioremediation serves as a suitable strategy to enhance soil quality particularly to remediate soils heavily contaminated with mixtures of PAHs.