Low Organic Matter Content Research Articles

Flash-Calcined Sediments for Zinc Adsorption

Heavy metal contamination of the environment could pose health risks to humans. Until recently, several geochemical routes were considered to address the issue of metallic leachates from sources such as e-waste deposal sites or mining areas. Following the adsorption pathway, this study focused on investigating the ability of calcination products as a low-cost option for the remediation of zinc contaminated effluents. Sediments dredged in northern France were calcined by flash calcination method, before testing the calcination products (FCS750 hereafter) as adsorbent for zinc removal. The calcination process performed at 750 °C resulted in a denser material with a higher specific surface area and lower organic matter content, suited for aqueous remediation. Kinetic and equilibrium assessment underlined a rapid adsorption better described with the Pseudo Second Order model than the Pseudo First Order or Bangham equations. Adsorption models (Langmuir, Freundlich and Temkin) implemented to describe the interaction under two pH conditions (pH = 2; pH = 7) resulted in a maximum adsorption capacity (qmax) of 89.61 mg g−1 under the most favourable configuration. The pH conditions had poor influence on the adsorbing capacity value, which suggested a good buffering property of the calcined sediment and a potential applicability on effluents with different chemistries. A qmax comparison based on 42 studies indicated that FCS750 was more beneficial than most raw organic adsorbents but remained less effective than grafted and composite materials. Nevertheless, the low number of steps necessary for FCS750 processing, the easy access of its precursor (harboring wastes) and its low energy cost suggested good economic competitiveness and pleaded in favor of field experimentations.

Assessment of soil health in uncontrolled grazing areas in the Administrative Post of Luro, Lautem, East Timor

Abstract. Costa DD. 2023. Assessment of soil health in uncontrolled grazing areas in the Administrative Post of Luro, Lautem, East Timor. Intl J Trop Drylands 7: 46-54. Uncontrolled grazing practices have been judged as the main cause of soil degradation in grassland areas. This study was conducted to provide baseline information on soil health in uncontrolled grazing areas in the administrative post of Luro, municipality of Lautem, East Timor (Timor Leste). Furthermore, 40 soil samples were collected from eight uncontrolled grazing areas using the core method; five points sampling per each site (four in corners and one in in the center) sampling points distances were 100 to 150 m apart, and each point represented three different soil layers (0-5 cm, 5-10 cm, and 10-20 cm). All soil samples were transported to the laboratory of the Faculty of Agriculture, Universidade Nacional Timor Lororsae, East Timor. Samples preparation and analysis followed the procedure and guidelines of McKenzie et al. (2002) and Liu et al. (2019) for physical properties, while Soil Organic Matter (SOM) analysis used Loss-On-Ignition (LOI) adopted from Nakhli et al. (2019). In addition, all soil chemical properties were analyzed using Kjeldhal and Bray-1 method following the soil analysis guidelines of JICA (2014). The study showed that soil physical properties in the uncontrolled grazing areas in Luro are characterized by high bulk density, poor porosity, and low organic matter content. Furthermore, soil pH remains neutral in areas where uncontrolled grazing is practiced but with very low nitrogen and potassium levels. In contrast, phosphorus is very high in the Cotamuto and Lakawa but very low in the Afabubo areas. Furthermore, low literacy levels and livelihoods are key socioeconomic factors that directly influence uncontrolled grazing practices. Hence, promoting sustainable grazing methods among communities towards raising livestock for their livelihood is recommended.

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.

Assessment of physicochemical properties of some cultivated floodplains in Ekiti State, Southwest Nigeria

Crop productivity depends to a large extent on the physicochemical properties of soil on which it is grown because the later has direct relationship to the nutrient requirements and uptake of crops. Floodplains are notable for seasonal utilization to produce crops especially fruits and vegetables for our teeming population. However, the floodplains can be affected by rainfall/storm regime in a way that can impact nutrients availability negatively. It is on this premise that this research was conducted to investigate physicochemical properties of some floodplains in Ekiti State, Nigeria to ascertain their suitability for crop production. Soil samples (0-30 cm) were collected at 5 m, 25 m and 45 m perpendicular distance to each of the three river parts at upper, middle and lower portion of the river channel. The samples were air-dried, milled, sieved and subjected to physicochemical analyses using standard methods. The ranges of the physicochemical properties are pH (5.02-7.13), electrical conductivity (34.00-571.00 μS/cm), organic matter (0.14-3.77 %), nitrogen (0.03-1.47 %), Ca2+ (0.23-4.94 cmol/kg), Mg2+ (0.15-4.64 cmol/kg), Na+ (1.20-3.62 cmol/kg), K+ (2.15-19.75 cmol/kg), Al3+ (0.41-23.02 cmol/kg), H+ (0.34-28.71 cmol/kg) and CEC (9.53-65.32 cmol/kg). In general, the floodplains are slightly acidic with low organic matter content typical of West African sub-region, sandy loam with moderate cation exchange capacity. It is recommended that the floodplains under study be treated to reduce the exchangeable sodium percentage for better crop production. The acidic soils are also recommended to be limed in order to prevent the possibility of pollutants like heavy metals from entering into the food chain. Recommendations are made to improve the soils’ physicochemical condition for increased food production.

Effect of the association of coagulation/flocculation, hydrodynamic cavitation, ozonation and activated carbon in landfill leachate treatment system

Mature landfill wastewater is a complex effluent due to its low biodegradability and high organic matter content. Currently, mature leachate is treated on-site or transported to wastewater treatment plants (WWTPs). Many WWTPs do not have the capacity to receive mature leachate due to its high organic load leading to an increase in the cost of transportation to treatment plants more adapted to this type of wastewater and the possibility of environmental impacts. Many techniques are used in the treatment of mature leachates, such as coagulation/flocculation, biological reactors, membranes, and advanced oxidative processes. However, the isolated application of these techniques does not achieve efficiency to meet environmental standards. In this regard, this work developed a compact system that combines coagulation and flocculation (1st Stage), hydrodynamic cavitation and ozonation (2nd Stage), and activated carbon polishing (3rd Stage) for the treatment of mature landfill leachate. The synergetic combination of physicochemical and advanced oxidative processes showed a chemical oxygen demand (COD) removal efficiency of over 90% in less than three hours of treatment using the bioflocculant PGα21Ca. Also, the almost absolute removal of apparent color and turbidity was achieved. The remaining CODs of the treated mature leachate were lower when compared to typical domestic sewage of large capitals (COD ~ 600 mg L−1), which allows the interconnection of the sanitary landfill to the urban sewage collection network after treatment in this proposed system. The results obtained with the compact system can help in the design of landfill leachate treatment plants, as well as in the treatment of urban and industrial effluents which contains different compounds of emerging concern and persistence in the environment.

Phytoremediation potential of native plants: Biomonitoring approach in contaminated soils

Phytoremediation has been used to remediate contaminated site. This study aims to investigate the potential of the selected native plants to accumulate and tolerate chemical pollutants. Two sites were selected in Southern Tunisia lands (Gabès), i) Gannouch located near the chemical industrial complex and ii) Zerkineis around 35 kilometres far from the industrial activities. Soil and plants were sampled and analysed for cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn) and fluorine (F) concentrations. The native plants were Bassia indica and Chenopodium album, with no obvious morphological toxic symptoms. Results indicated that the upper soil layers were alkaline and salt affected with low organic matter content. The highest levels of fluoride and heavy metal were found in Ghannouch. The contents of Cd, Cu, Pb, Zn and F in the roots, stem and leaves of the native plants exceed the normal ranges and the phytotoxic level. Bioconcentration factor (BCF), translocation factor (TF), and biological accumulation factor (BAF) were determined for each element. Based on these factors the selected plants were classified as excluders, indicators, and accumulators for each element. The native plants, studied herein, seems to have significant potential for phytoremediation, thus they may be used as biomonitors in contaminated soils. Bassia indica identified as Cd, Cu and Pb accumulator, could be an excellent candidate for phytoextraction and phyto stabilization because of its F excluder performance.

Application of Vermicompost, Kasgot (BSF Compost), and Vermigot for growth and production of Pakchoy (Brassica rapa L.) in Ultisol

Ultisol have low organic matter content, acid pH, very low available nutrients, and high Al, therefore compost application is needed as a source of nutrients for plants in Ultisol. Vermicompost, which is produced from the decomposition of certain organic matter by earthworms. However, there is another decomposer that is producing compost, Black Soldier Fly larvae, it is called Kasgot (BSF compost). The new compost from combination of the two types both of compost is called Vermigot. This study aimed to examine the combination of vermicompost and kasgot from cow dung and banana stems on the growth of pakchoy in Ultisol soil. This study used a factorial randomized block design (RAK). The first factor is the type of compost (K): K1 (vermicompost), K2 (kasgot) and K3 (vermigot). The second factor is the dosage (D): D1 (100 g/pot), D2 (200 g/pot), and D3 (300 g/pot). The treatment was repeated two times so that 27 treatments were obtained. The best compost that could be used to increase the growth and production of pakchoy was vermigot compost 200 g/pot, while the type of compost with the best chemical characteristics and nutrient content in Ultisol soil was vermigot at a dose of 300 g/pot.

Assessment of Soil Quality Index in the Southern Coastal Sandy Soils of Kerala, India

Context: The Indian state of Kerala has a long coastline of 589.50 km all along its western border, which has a great potential in biomass production. The agro-ecological unit 1 (AEU 1) in Kerala represents the southern coastal plains, with typical sandy soils. The major constraints of these coastal sandy soil with regard to agriculture are: low organic matter and clay content, as well as their poor water holding capacity, resulting in limited ability to hold nutrients.
 Aims: A study was carried out to evaluate the physico-chemical parameters and quality of the soils of coastal sandy soils in AEU 1.
 Methods: Fifty geo-referenced composite soil samples were taken from different locations of AEU-1 in Thiruvananthapuram district, and were characterised for physical, chemical and biological attributes. Principal component analysis (PCA) was carried out for the analysed soil properties which resulted in 6 principal components (PCs) and a minimum data set (MDS) was obtained using the selected indicators i.e., texture (clay %), water holding capacity, bulk density, soil pH, organic carbon, available nutrients such as potassium, sulphur, zinc, manganese and boron. The soil indicators were changed to unit-less scores after the development of MDS, and were assigned with appropriate weights based on existing soil conditions and soil nutrient content.
 Key Results: Value of SQI recorted the highest in Kadakkavoor and the lowest in Anchuthengu. Further, the locations were classified into three groups namely poor, medium, and good, based on the relative soil quality index (RSQI). Less than 50% of RSQI is considered poor, from 50% to 70% is medium, while more than 70% is considered good. From the study, majority of the land area (60% of samples) in AEU 1 of Thiruvananthapuram district were observed to have a medium level of relative soil quality index.

Effects of Citric Acid and Humic-like Substances on Yield, Enzyme Activities, and Expression of Genes Involved in Iron Uptake in Tomato Plants

Iron (Fe) deficiency is a common abiotic stress on plants growing in calcareous soils where low organic matter content, high carbonate–bicarbonate concentration, and high pH precipitate Fe in unavailable forms. Enzymatic activity is a mechanism for plants to access soil nutrients; enzymes such as H+-ATPase, phosphoenolpyruvate carboxylase (PEPC), and the intracellular enzyme ferric reduction oxidase (FRO) are involved in Fe absorption. The effects of the application of citric acid (CA) and humic-like substances (HLS) on the yield, H+-ATPase, PEPC, and FRO enzyme activity, and expression of LeHA1, LePEPC1, and LeFRO1 genes in tomato plants grown under calcareous soil were studied. CA and HLS improved the SPAD units and increased the number of harvested fruits and yield per plant. Temporary alterations in enzyme activity, which reduced PEPC and FRO activity in roots, were documented. In leaf tissue, CA resulted in lower expression of LeHA1 and LePEPC1 and the induction of LeFRO1 expression, whereas HLS application resulted in higher expression of LePEPC1 and LeFRO1. In roots, LeHA1 expression increased with HLS, whereas LePEPC1 and LeFRO1 showed lower expression with CA and HLS, respectively. The application of CA and HLS through a nutrient solution in combination with Fe-chelate can improve Fe nutrition in tomato plants potted in calcareous soil by inducing temporal alterations in PEPC and FRO enzyme activity and LeFRO1 and LeHA1 gene expression.

Spatial Variability Mapping of Selected Soil Properties of District Tando Allahyar, Sindh, Pakistan

Spatial variability mapping of soil properties is essential to understand the differences among soils found in a geographical region for their better management. This study aimed at spatial variability mapping of selected soil properties of district Tando Allahyar, Sindh which is one of the most important districts of Sindh province. The results revealed that majority of soils (35.6%) had loamy slightly medium-textured type, including 30.8% silt loam, 3.8% loam and 1.0% silt, followed by clayey, fine-textured heavy type (27.9%), including 18.3% clay, 6.7% silty clay and 2.9% sandy clay. Soils with sandy, coarse-textured light type were 20.2%, including 16.3% sandy loam and 1.9% loamy sand and sand each. Soils with loamy, moderately medium-textured type were 16.3%, including 9.6% clay loam and 6.7% sandy clay loam, while silty clay loam soil texture was total missing. The EC ranged from 0.14 to 4.44 dS m-1 (mean: 0.69 dS m-1, mode: 0.42 dS m-1). Majority (91%) of soils had low (46%) to medium (45) level of salinity. Soil pH ranged from 6.2 to 8.6 (mean: 7.7, mode: 8.3). Majority of soils (84%) had either slightly (24%), medium (22%) or strongly alkaline (38%) soil pH. Interestingly, some soils (13%) had slightly acidic pH. Organic matter ranged from 0.10 to 1.6% (mean: 0.64%, mode: 0.17%). Majority (84%) of soils were deficient in organic matter. Soil ABDTPA-P ranged from 1.2 to 18.8 mg kg-1 (mean: 5.38 mg kg-1, mode: 2.4 mg kg-1). More than half (55%) of the soils had low P, while soils with marginal (14%) or adequate (31%) P were also present. Soil ABDTPA-K ranged from 31 to 376 mg kg-1 (mean: 154 mg kg-1, mode: 230 mg kg-1). Majority of soils (62%) had adequate K, while soils with marginal (28%) or low (11%) K were also found. Spatial variability mapping revealed the dominance of loam, sandy clay loam, sandy loam, silty clay and clay loam textures, medium > low and high > salinity, slightly to medium alkaline soils > strongly alkaline soils, low organic matter content, medium to adequate > low soil P, and adequate soil K. The spatial variation found in various soil properties of district Tando Allahyar, Sindh must be taken in mind while deciding about their site-specific management, using the recently developed maps.

Dry-to-wet fluctuation of moisture contents enhanced the mineralization of chloramphenicol antibiotic

Due to livestock wastewater irrigation, soil is becoming one of the major sinks of antibiotics in the environment. Recently, it is getting recognized that a variety of minerals under low moisture conditions can induce strong catalytic hydrolysis to antibiotics. However, the relative importance and implication of soil water content (WC) for natural attenuation of soil residual antibiotics has not been well recognized. In order to explore the optimal moisture levels and the key soil properties dominating for the high catalytic hydrolysis activities of soils, this study collected 16 representative soil samples across China, and assessed their performances to degrade chloramphenicol (CAP) under different moisture levels. The results showed that the soils with low organic matter contents (< 20 g/kg) and high amounts of crystalline Fe/Al were particularly effective in catalyzing CAP hydrolysis when exposed to low WC (< 6%, wt/wt), leading to CAP hydrolysis half-lives of <40 d Higher WC greatly suppressed the catalytic activity of the soil. By utilizing this process, it is possible to integrate abiotic and biotic degradation to enhance the mineralization of CAP, attributing to that the hydrolytic products are more available for soil microorganisms. As expected, the soils experienced periodic dry-to-wet moisture conditions (i.e., the WC shifting from 1 to 5% to 20–35%, wt/wt) exhibited higher degradation and mineralization of 14C-CAP, in comparison with the constant wet treatment. Meanwhile, the bacterial community composition and the specific genera showed that the dry-to-wet fluctuation of soil WC relieved the antimicrobial stress to bacterial community. Our study verifies the critical role of soil WC in mediating the natural attenuation of antibiotics, and guides to remove antibiotics from both wastewater and soil.

Analysis of Water Infiltration Characteristics and Hydraulic Parameters of Sierozem Soil under Humic Acid Addition

The farmland in Yinchuan is composed of sierozem soil, which is characterized by high sand content and low organic matter content, resulting in poor water-holding capacity and weak soil structure. Humic acid is a natural organic polymer soil amendment. It is critical to study how humic acid affects soil water infiltration in sierozem soil at the microlevel. A one-dimensional vertical infiltration experiment was conducted to explore how adding different amounts of humic acid (0, 1%, 2%, 3% and 4%) affected the infiltration characteristics and hydraulic parameters of the sierozem soil. The results revealed that the wetting front and cumulative infiltration decreased with the increase in humic acid addition. When the infiltration time was 90 min, the wetting front of the 1%, 2%, 3% and 4% treatments was 6.50%, 10.00%, 15.00% and 21.00% lower than CK (0 for CK), and the cumulative infiltration volume was 4.50%, 11.14%, 18.42% and 23.60% lower than CK, respectively. Among the three infiltration models created by Philip, Horton and Kostiakov, the Kostiakov model (R2 &gt; 0.95) could more accurately describe the soil water infiltration process in the study area. After infiltration, the moisture content of each soil layer increased with the increase in humic acid, which improved the water-holding capacity of the sierozem soil. Using Hydrus-1D to calculate soil hydraulic parameters, we found that the humic acid addition affected the hydraulic parameters. With the increase in the amount of humic acid addition, the retention water content θr and saturated water θs were positively correlated with the humic acid addition amount and negatively correlated with the saturated water conductivity Ks and the reciprocal of air-entry α. The results showed that humic acid could increase the water-holding capacity of soil and improve the rapid water loss and poor water-holding capacity of sierozem soil.

STATUS AND FORMS OF SULPHUR IN SOILS OF WUDIL AND GAYA, KANO STATE, NIGERIA.

An investigation study was carried out to determine the status and forms of sulphur in soils of Wudil and Gaya, Kano state, Nigeria. Soils were collected using grid sampling method across two farming communities, Gaya and Wudil Local Government areas of Kano state. A total of 297 samples were collected at a depth of 0 - 30 cm. The samples were subjected to routine soil tests while the forms of sulphur were determined using turbidmetric method. Descriptive analysis was used for the interpretation of the data. The result obtained showed that soils from both locations were sandy loam with slightly acidic to neutral pH and low content of organic matter (0.38 and 0.24%) and nitrogen (0.06 and 0.04%). The sulphur level in both locations was sufficient. Differences in the concentration of the forms of sulphur were observed. Total sulphur had the highest amount of sulphur 498.30 mg kg-1, while non-sulphate sulphur had the least amount 0.74 mg kg-1. The low amounts of adsorbed and non-sulphate sulphur observed were attributed to the texture (sandy loam) and pH (6.24 and 6.99) of the soil. It can be concluded that the sulphur levels in both locations; Gaya and Wudil were high. Therefore, management strategies that will enable sulphur mineralization in the soil should be maintained by farmers to enhance availability of sulphate in the soil.

THE COMBINED EFFECT OF THE TILLAGE DEPTH AND COMPOST APPLICATION ON CALCAREOUS SOIL AGGREGATES AND THE YIELD OF INTERCROPPED FABA BEAN WITH WHEAT

Calcareous soils crusting and low organic matter (OM) content are key problems restrict their management and productivity. The aim of this study is to assess the role of tillage at different depths along with the compost application for improving some characteristics of the calcareous soil as well as the yield, and its components of the intercropped faba bean with wheat (1:1 ratio). A field experiment was carried out at the Nubaryia Agricultural Experimental Station through the two successive winter seasons (2019/2020) and (2020/2021) in a split-plot design with three replicates. The main factor (F1) was the plough depth treatments: Chisel plough (20 cm depth) and subsoiler (40 cm depth) one time and twice. The sub-factor (F2) was the applied compost (C1= 5.95 and C2= 11.9 tons ha-1). A control without additions was involved. The wheat and fababean were sown in a 1:1 intercropping ratio mixed with the surface layers by hatchat under a surface irrigation system and the recommended agronomic practices were followed. The tillage treatments combined with increasing the rate of the applied compost have increased the total stable aggregates (TSA), the aggregation index and aggregation degree in the surface and subsurface soil layers (0 – 20 cm, 20 – 40 cm) as well as the saturated hydraulic conductivity (Ks) for both seasons. The water stable aggregates (WSA) distribution revealed that the 8-2 cm aggregates are the abundant size especially in the surface soil layers. The 40 cm depth subsoiler twice treatment combined with the compost rate C2 resulted in the maximum OM for both seasons. The relative maximum OM increase (%) compared to the corresponding control was by 32.3 and 26.7% in the 0 – 20 cm soil layer and by 64.9 snd 60.0% in the 20 – 40 cm soil layer. For the compost rate C2, the most significant relative increase in the wheat grains yield (kg ha-1) was by 74.8% with the plowing two times at 40 cm depth, while for the faba bean seeds yield (kg ha-1) it increased by 145.5% with the 20 cm depth plowing. The studied treatments were effective for improving the calcareous soil properties and productivity.

DISTRIBUTION OF BOTTOM SEDIMENT BEFORE AND AFTER RECLAMATION AT CENTER POINT OF INDONESIA (CPI) MAKASSAR CITY

Characteristics and distribution of bottom sediment is one of the important parameters in determining the management plan and land use in coastal areas. The purpose of this study was to determine the condition of the distribution of bottom sediments and to compare the changes that occurred in the distribution of bottom sediment before and after the reclamation of the Center Point of Indonesia (CPI) in Makassar City. Sediment sampling was carried out using a grab sampler at four stations, namely stastions on the island adjacent to the reclamation area and two other stations in the water around the reclamation area. The results showed that the bottom sediment in the waters around the reclamation area consisted of coarse sand and medium sand with an organic matter content of 14.92% in the sediment. On the islands adjacent to the reclamation area, the bottom sediments are move varied, consisting of coarse sand, medium sand and fine sand with lower organic matter content of 4.92% to 5.38%.

Gas Desorption Characteristics of the Chang 7 Member Shale in the Triassic Yanchang Formation, Yan’an Area, Ordos Basin

In the Yan’an area of the Ordos Basin, the lithological heterogeneity of Chang 7 Member shale is extremely strong. In addition, sandy laminae is highly developed within the Chang 7 Member shale system. In order to explore the gas generation and migration processes of Chang 7 Member shale, geochemical characteristics of desorption gas are comprehensively compared and analyzed. In this study, rock crushing experiments were carried out to obtain shale samples, and desorption experiments were carried out to obtain shale samples and sandy laminated shale samples. For the crushing gas and desorption gas, the volume contents of different gas components were obtained using gas chromatography experiments. The rock crushing experiments revealed that the average volume percentage of CH4 in Chang 7 Member shale is 61.93%, the average volume percentage of C2H6 and C3H8 is 29.53%, and the average volume percentage of other gases is relatively small. The shale gas in Chang 7 Member is wet gas; the gas is kerogen pyrolysis gas. Most of the shale gas hosting in Chang 7 Member shale is adsorbed gas. Porosity, permeability and organic matter content are the main geological factors controlling gas migration and gas hosting. Shale with a higher porosity, good permeability and a low organic matter content is conducive to gas migration. The shale gas in Chang 7 Member shale contains CH4, C2H6, C3H8, iC4H10, nC4H10, iC5H12, nC5H12, CO2 and N2. N2 migrates more easily than CH4, and CH4 migrates more easily than CO2. For hydrocarbon gases, gas components with small molecular diameters are easier to migrate. The desorption characteristics of shale might provide clues for guiding hydrocarbon exploration in the study area. The sandy laminated shale with a higher gas content may be the “sweet spot” of shale gas targets. In Chang 7 Member, the locations hosting both shale oil and CH4 may be the most favorable targets for shale oil production.

Remediation of arsenic-contaminated calcareous agricultural soils by iron-oxidizing bacteria combined with organic fertilizer.

In arid soil with low-iron and high-calcium carbonate contents, the fate of arsenic (As) is mainly controlled by the contents of calcium and organic matter in the soil. However, there is still a lack of knowledge about their interaction and that effect on their absorption by maize. The purpose of this study was to explore the long-term immobilization and repair mechanism of in situ As-contaminated farmland. We designed three treatments: iron-oxidizing bacteria (FeOB), organic fertilizer, FeOB and organic fertilizer added in combination. After 140-day field farmland remediation trial, the results showed that the FeOB can effectively immobilize the water-soluble As (FS1) in soil, and the organic fertilizer promoted the remediation of FeOB. In addition, the content of As in maize grains was reduced after treatment by FeOB and organic fertilizer. The XRD and XPS analysis of the topsoil showed that the combined treatment of FeOB and organic fertilizer promoted the formation of calcium arsenate mineral with low solubility and high stability; As(III) would gradually transform into As(V). The biological iron (hydr)oxide can increase the contents of Fe and As in the rhizosphere and form iron plaques on the surface of the roots by SEM-EDS analysis of maize root. Collectively, these results clarify the main biogeochemical ways to control the fate of As in calcareous soils with low-iron and low-organic matter contents and provide a basis for in situ remediation of As.

A novel photoelectrocatalytic reactor with Fenton-like BiFeO3-TNTAs electrode for treatment of reclaiming water

The reuse of reclaimed water has been limited by the ecological and human health risks of the residual trace organic pollutants, antibiotic-resistant bacteria and antibiotic resistance genes it often contains. The emerging photoelectrocatalytic technology may be able to break through this bottleneck. Nevertheless, the detailed information about such technology in the reclaiming water treatment has not been fully addressed. A laboratory-scale photoelectrocatalytic purification system was constructed using TiO2 nanotube arrays doped with BiFeO3 nanoparticles as the anode and carbon/polytetra-fluoroethylene as the cathode. The anode was stable with excellent optical and electrochemical properties. About 5.6 log of antibiotic-resistant bacteria were inactivated within 30 min, and 60% of free antibiotic resistance genes were removed within 60 min. The effective removal was mainly due to mutual promotion between photoelectrocatalysis and Fenton reactions which produced abundant active radicals. Low concentrations of effluent organic matter promoted the inactivation. The process was demonstrated in a bench-scale reactor treating 17α-ethinylestradiol and antibiotic-resistant bacteria with high removal rates. The designed photoelectrocatalytic reactor can provide efficient technology for the reuse of reclaiming water.

Organic Matter Assessment and Paleoenvironmental Changes of the Middle Jurassic Main Source Rocks (Khatatba Formation) in the North Western Desert, Egypt: Palynofacies and Palynomorph Perspectives

The Middle Jurassic in the north Western Desert, Egypt, was a time of complex tectonics and increased environmental perturbations attributed to the predominant sedimentation of organic carbon-rich fine siliciclastic and carbonate deposits of the Khatatba Formation. Although some studies have addressed the hydrocarbon potential and source rock characteristics of the Khatatba Formation, a regional-scale investigation of the prevalent paleoenvironmental conditions and organic matter characteristics is still necessary. In this study, the Khatatba Formation is investigated for detailed palynofacies analysis and palynomorph composition to assess organic matter kerogen types and reconstruct the depositional paleoenvironmental patterns on a regional scale. For this purpose, 116 drill cuttings were collected from five wells in the Matruh, Shushan, and Dahab-Mireir Basins. Moderately diverse assemblages of spores, pollen, and dinoflagellate cysts are reported. Age-diagnostic dinoflagellate cysts, including Adnatosphaeridium caulleryi, Dichadogonyaulax sellwoodii, Korystocysta gochtii, Wanaea acollaris, and Pareodinia ceratophora, along with occasional records of Systematophora areolate and Systematophora penicillate, defined a Bajocian–Callovian age. Based on particulate organic matter (POM) composition, four palynofacies assemblages (PFAs) are identified. PFA-1 is the most common within the Khatatba Formation in the five studied wells. It contains high proportions of phytoclast fragments versus low contents of amorphous organic matter (AOM) and palynomorphs and is defined by a gas-prone kerogen Type III. PFA-2 is comprised of moderate abundances of AOM and phytoclast characteristics of oil-prone kerogen Type II. PFA-3 is dominated by phytoclasts and moderate to low proportions of AOM and palynomorphs of kerogen Type III, whereas PFA-4 consists of AOM and palynomorphs defining kerogen Type II. PFA-1 indicates predominant deposition in proximal active fluvio-deltaic sources to marginal marine conditions with enhanced contributions of terrestrial/riverine influx. PFA-2 and PFA-3 reveal deposition under an enhanced dysoxic to anoxic proximal inner neritic shelf due to the abundant occurrences of spores and coastal to shallow marine dinoflagellate cysts. PFA-4 suggests deposition under enhanced suboxic to anoxic distal inner neritic conditions because of enhanced AOM and abundant proximate and some chorate dinoflagellate cysts. Thus, the Middle Jurassic experienced a predominantly marginal to shallow water column in this part of the southern margin of the Tethyan Ocean where the Matruh, Shushan, and Dahab-Mireir Basins were located.

Role of Rice Husk Biochar in Improving Soil Physical Properties of ex Gold-Mined Soil

Mining causes destructive soil properties, especially soil texture, water retention, and transmission. Applying biochar is the best way to improve soil physical properties. A glasshouse experiment was conducted to evaluate the role of biochar on soil physical properties based on a Completely Randomized Design (CRD) with four replicates. The research comprised six treatments (0, 4, 8, 12, 16, 20 t biochar ha-1). The results showed that the ex-gold-mined soil had coarse soil texture (sandy loam), high Bulk Density (BD) (1.43 g cm-3), low Total Soil Pores (TSP) (46.45%), low soil organic matter (SOM) content (1.27 %), very fast hydraulic conductivity (198.8 cm h-1). After biochar incubation, SOM increased (to 3.11%), soil BD decreased (to 1.16 g cm-3), TSP increased (to 54.17 %), water retention increased (at pF 1.0, 2.0, 2.54, and 4.2), plant available water (PAW) increased (into 8.33 %), and hydraulic conductivity decreased (into 24.70 cm h-1). However, applying 20 t biochar ha-1 still needs to bring the soil physical properties of the ex-gold-mined soil back into suitable soil for farming land.