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Land Use/Land Cover Evaluation Using Trajectory Maps Based on Landsat TM/OLI in Southwest China Full text
2022
Gong, Wenfeng | Liu, Tiedong | Liu, Tao | Duan, Xuanyu | Liu, Yueyang | Stott, Philip
This study mainly aims to detect the county-level spatio-temporal variability of LULCC (Land Use and Land Cover Change) spatial patterns in Southwest China. Multi-temporal Remote Sensing (RS) images (Landsat TM/OLI in 2000, 2005, 2010, and 2015) were applied to extract land use/cover types at each of the four-time nodes using the Support Vector Machine (SVM) method. Then, the trajectory map methodology was adopted to identify the spatio-temporal distribution characteristics of LULCC patterns throughout the given time series. According to the results, the area of unused land decreased continuously, 0.094% total. An evident decline of grassland by 2.17% was documented, and a notable increase was observed in forestland by 63.94 km2 during the period from 2000 to 2015. Water bodies, built-up land, and unused land showed no significant change throughout the study period. The conversion from grassland to forestland and vice-versa (code 13 or 31) was prominent due to an adjustment made to local forestry policy during the first two periods (2000-2005 and 2005-2010), accounting for 17.55% and 17.56% of the study region, respectively. The anaphase trajectory transition type occupied the smallest area of all the trajectory maps. By contrast, the repetitive trajectory was the leading land-use transition type and covered the largest area. Trajectory analysis provides an effective approach for detecting the spatio-temporal changes in LULCC patterns.
Show more [+] Less [-]Assessment of Flood Hazard Zonation Using Geographic Information System and Analytical Hierarchy Process: A Case Study of Tlawng River Watershed in Sairang, Mizoram, India Full text
2022
Malsawmtluanga, . | Vabeihmo, Ch.
Flood occurs when the water inundates normally dry ground, which could happen in a variety of ways like excessive rainfall, overflowing of embankments, dams, rivers, snowmelt, and other factors. Floods are one form of a natural hazard which are difficult to contain and control. A flood susceptibility mapping using Geographic Information System (GIS) and Analytical Hierarchy Process (AHP) techniques were carried out at Sairang village in Aizawl, Mizoram in Northeast India. The study area Sairang is situated on the banks of the Tlawng river, the longest river in Mizoram. Floods have wreaked havoc in Sairang frequently resulting in huge losses and damage to property with numerous loss of life over the years. The total study area is 131.27 sq km and the resulting flood hazard potential zonation map shows that 1/3 of the watershed area falls in Vey High and High Potential Flood Hazard Zonation areas.
Show more [+] Less [-]Environmental Geological Problems in Southwest China: A Case Study from the Researches of Regional Landslide Hazards Full text
2022
Li, Shuang | Wu, Xiang | Sun, Faming | Yang, Jie | Li, Jian
Humans have paid a lot of attention to environmental geological challenges in recent years. Landslides, being one of the most prevalent geological disasters, are characterized by their suddenness and destructiveness. Southwest China is prone to landslides and debris flows due to its unique geological structure. This paper uses landslides in southwest China as an example, focusing on research on landslide initiation mechanisms and outlining modern landslide monitoring devices and prediction models. Landslides are caused by external variables such as persistent precipitation, groundwater movement, and significant seismic activity, as well as interior reasons such as fine particle rearrangement and the action of positive pore water. The reduction of the friction coefficient of the shear surface, which is induced by the increase of the shear rate, the supercritical carbon dioxide and superheated steam of the shear zone, and the mineral recrystallization process on the shear surface, all have an important impact on reducing the friction coefficient of the shear surface, is a key factor in the occurrence of high-speed remote landslides. Real-time landslide monitoring using space-air-ground and acoustic emission technology, as well as the creation of machine learning-based forecast models, have aided in the research of landslide development and early warning.
Show more [+] Less [-]Preparation of Copolymer of 2-Methacryloyloxyethyldimethyl-3-sulfonic Acid Propylammonium Hydroxide and 3-(Methacryloyloxy) Propyltrimethoxysilane and Its Dye Adsorption Properties Full text
2022
Xi, Fenfen | Liang, Liping | Tan, Weishou | Dong, Yanyan | Yu, Linshuang | Ma, Huiting | Yue, Gaosheng | Meng, Xu
While printing and dyeing bring us huge economic benefits, it also brings us huge challenges. Printing and dyeing will produce a large amount of wastewater, and the treatment of printing and dyeing wastewater has always been a concern. This work uses 2-methacryloxyethyl dimethyl-3-sulfonic acid propyl ammonium hydroxide, 3-(methacryloxy) propyl trimethoxysilane, and N, N’-methylene bispropylene as raw materials, and a photoinitiator is used to initiate polymerization under an ultraviolet lamp to prepare a copolymer gel. Taking the aqueous solution containing soap yellow as simulated dye wastewater, the adsorption performance of the prepared polymer for dyes was investigated. An ultraviolet spectrophotometer was used to investigate the effects of adsorption time, initial dye concentration, and polymer dosage on the adsorption performance. The performance test results show that the prepared polymer has high adsorption and removal efficiency for dyes containing soap yellow simulation, and has a potential application value.
Show more [+] Less [-]Effect of Surface Modification on the Characteristics of Sisal Fiber Reinforced Concrete Treated with Na2CO3 Full text
2022
Abirami, R. | Sangeetha, S. P.
Concrete with fiber as a reinforcing material is one of the important fields of research that is gaining traction in this upcoming green technology revolution. By adding fibers to concrete, the tensile strength properties are vastly improved without compromising the strength characteristics, and cost fluctuation is minimal. This research is being carried out to improve the qualities of concrete that have been infused with chemically treated sisal fiber in varied ratios. The paper investigates and describes the effects of sisal fiber when it is chemically treated and infused with concrete, comparing it to ordinary concrete in strength tests. Water absorption, workability, and other material characteristics of Sisal fiber reinforced concrete with 0.5 per cent, 1 per cent, 1.5 per cent, and 2 per cent fiber replacing cement by volume fraction and a sisal fiber aspect ratio of 1:100 are compared to the traditional M30 concrete grade. After being treated with an alkaline solution, 0.5 per cent and 1 per cent sisal fiber reinforced concrete increased tensile and compressive strength, as well as the formation of calcium carbonate deposits on the fiber interfaces; this also contributes to the concrete’s corrosion resistance and durability.
Show more [+] Less [-]Properties and Distribution of Seed Banks in a Black Locust (Robinia pseudoacacia) Plantation in Central China Full text
2022
Zhang, K.Q. | Yang, X.C. | Shen, Z. | Ma, L.Y. | Duan, J. | Li, Y.
We aimed to compare the properties of seed banks in different types of Robinia pseudoacacia stands and different substratum layers. We established four Black locust plots (each 50 × 50 m) that included two second-generation stands and two third-generation stands. Spatial coordinates, diameter at breast height, and the heights of all trees were measured in the four plots. In each plot, we set a total of 259 points using the regular grid design method. At these points, we sampled the seed banks in the litter and soil (0-5 cm) layers. The coordinates of the 259 points were recorded. After the samples had been collected and screened, a germination trial was performed using the collected seeds from the different layers and stands. We used variogram and kriging interpolation geostatistical methods to analyze the distribution of the seed banks. A kernel density estimation map was generated to examine the relationship between the seed bank and trees in each stand. The results showed that seed bank density was high in the four stands (4005-7325 seeds.m-2), and was higher in the third-generation stands (6085 and 7325 seeds.m-2) than in the second-generation stands (4005 and 5659 seeds.m-2). The seed bank density in the litter layer (3225 seeds.m-2) exceeded that in the soil layer (2164 seeds.m-2). The spatial pattern of the seed banks varied among different stands and was positively correlated with the distribution of trees in each stand. Furthermore, we found that spatial autocorrelation in the seed banks occurred at a variety of scales. Seeds in the litter layer were significantly more active than those in the soil layer; the germination rate varied from 6.67% to 28.89%. The findings of this study suggest that the Robinia pseudoacacia plantation in the Luoning area may exhibit potential for regeneration from seeds, and this will be the focus of our future studies.
Show more [+] Less [-]Pollution Characteristics of Surface Sediments in Luhun Drinking Water Reservoir in the Middle China Full text
2022
Zhou, Zizhen | Xu, Yu | Dai, Zhen
The pollution status of surface sediments in the Luhun drinking water reservoir in the central of China was analyzed and evaluated, and three sampling points were selected for this study. The results showed that the organic matter content of the Luhun reservoir was as high as 5.2%, which was at a high level. The analysis of nitrogen, phosphorus, and their components showed that the total nitrogen (TN) and total phosphorus (TP) pollution in Luhun reservoir was in the medium pollution level, among which the ion-exchange state of nitrogen component and the strong-alkali extraction state of phosphorus component accounted for a relatively high risk of release into the overlying water. The results showed that the bioavailability index of Pb and Cr was as high as 0.73 and 0.62, which was of big pollution risk. Generally speaking, the sediment of Luhun reservoir had a high risk of pollution to the overlying water. The results of this study can provide a theoretical basis for urban safe water supply and provide support for water quality improvement.
Show more [+] Less [-]Low-Cost Calibration MOS Gas Sensor for Measuring SO2 Pollutants in Ambient Air Full text
2022
Purbakawaca, R. | Yuwono, A.S. | Subrata, I.D.M. | Alatas, H.
Air pollution has evolved into a global issue that necessitates immediate and accurate pollution control. The usage of the Metal Oxide Semiconductor (MOS) sensor as a monitoring system for air pollution levels is one possible answer to this challenge. The MQ-136 sensor is calibrated using standard SO2 (0, 5, 10, 20, 30, 40, 50, 60, 70) ppm as the test gas in this study. To collect the sensor output signal, a variety of equipment was created, including a gas test box, a voltage divider, and follower circuit, and a gas flow control unit operated by a microcontroller. The test gas can be pumped into the test box at a constant rate of 1.0 L.min-1 by the apparatus. To evaluate a significant difference (= 0.05), an analysis of variance was performed on the response signal generated by a series of sensors due to the concentration of the test gas. To examine the correlation between the sensor response signal and the test gas concentration treatment, as well as the sensor performance, linear regression analysis was used. The ANOVA results demonstrate no significant differences amongst the sensors, indicating that they all follow the same routine. Furthermore, ANOVA analysis reveals that the sensors respond differently at each level of SO2 concentration. According to linear regression, the relationship between gas concentration and sensor-1, sensor-2, and sensor-3 output signals is reflected by coefficients of determination of 0.94, 0.91, and 0.93, respectively.
Show more [+] Less [-]Insight into Effects of Initial Moisture Content on the Heat-Up of Sewage Sludge Composting During Mesophilic Phase Full text
2022
Li, Yu | Su, Yuran | Hu, Bin | Ma, Chuang
The effects of initial moisture content (55%, 60% and 65%) on the heat-up of sewage sludge (SS) composting during the mesophilic phase were investigated. Monitoring results showed that low moisture content (55%) increased the heating rate, high initial moisture content (60% and 65%) significantly improved the activities of cellulase and peroxidase during the mesophilic phase. Furthermore, although high moisture content improved the diversity of bacteria during composting, there were no significant differences in the microbial structure during the process of succession. So, rather than inhibiting the activity of the bacterial population, the negative effect of high moisture content (60 and 65 per cent) on composting temperature heat up was attributable to the difficulty of heating produced by the specific heat capacity of water. The correlation index between initial moisture content and microorganisms was relatively low, while the temperature was the largest environmental factor affecting the bacterial community. This conclusion provided a hint to make an association between initial moisture content and composting temperature-rising stage.
Show more [+] Less [-]Use of Agricultural Waste-Based Biosorbents for the Removal of Heavy Metals from Aqueous Solution: A Review Full text
2022
Harshala, K. | Wagh, N. D.
Agriculture is the immemorial benefaction of man for the existence and welfare of the human race. Being an agricultural country, it is the prime source of livelihood in India. This review focused on the present scenario of Indian Agriculture with respect to crop production, factors affecting productivity, and agricultural waste-related issues in India. Agrowaste can be helpful to farmers but economic costs are less than the cost of collection, transportation, and processing for profitable use. In this consequence, the review has presented considerable information on the alternative use of agrowaste to control water pollution. The review focused the light on the replacement of conventional chemicals with agro-based waste to develop fully green and sustainable biosorbents. It also highlighted the potential of biosorbents and biosorption technology in terms of their adsorption capacities, cost-effectiveness, binding mechanisms, and interfering factors such as pH, temperature, initial concentration, dose, and pre-treatments. Biosorption isotherms and sorption kinetics models were used for the characterization of agrowaste and developed biosorbent, and recovery of sorbent was also reviewed. The review concluded that further research is required to investigate novel biosorbents that may be a good option for bioremediation for the removal of a large range of toxic heavy metals. The utilization of plant waste as biosorbent will also open a new window of agricultural waste management.
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