Rice paddies have been identified as major methane (CH4) source induced by human activities. Water management is an important factor affecting CH4 emission during the rice growing season, and the water depth in a rice field directly affects the production, oxidation, and transfer. Field experiments on irrigation management are generally conducted under three modes: control irrigation, intermittent irrigation, and long-term flood irrigation. Static opaque chamber gas chromatographic method was adopted in this work for in situ observations of CH4 emission flux in a field in the rice growing season in a cold region of China. Test data from 2016 was adopted to establish the single factor and interaction types of the CH4 emission flux estimation model for the rice growing season under different water management methods, and the data from 2017 was used for model inspection. The estimation models were based on NO3-N in soil and soil temperature, 10 cm under the soil surface. All models passed the significance test for significance levels of P<0.01. The average forecast error of the model is 13.53-24.78%, and the coefficient of determination Radj2 is between 0.399-0.675. The calculated values of the model are consistent with the measured values. The model established in this research can be used for estimation of CH4 emission in the rice growing season in cold regions of China for different water-saving irrigation modes.

The adsorption of methylene blue in an aqueous medium using two activated carbons AC1 and AC1 + H3PO4 was studied. The AC1+ H3PO4 adsorbent, which was inoculated with phosphoric acid, had better methylene blue removal capacity compared with AC1 adsorbent which had only thermal treatment. The optimum activation temperature for both adsorbents was 500°C while the suitable activation time was 180 min. The best pH in this investigation was 6. With AC1 + H3PO4 adsorbent, 100% removal of methylene blue was recorded for concentrations 20 to 100 mg.L-1 and the suitable adsorbent dosage was 3 g.L-1. The effect of temperature showed insignificant effect on the adsorption of methylene blue ions. The SEM results for AC1 + H3PO4 adsorbent showed better pores compared with AC1, an indication that the injection of phosphoric acid into it before the activation played a significant role in enhancing the porosity of the adsorbent surface.

The source region of the Yellow River, located in the north-eastern edge of the Qinghai-Tibet Plateau, is an important water conservation region and ecological barrier of the Yellow River. In this paper, based on remote sensing technology, multi-period Landsat remote sensing images in the source region were taken as the main information source. With the assistance of field investigation, we monitored the spatial and temporal changes of desertification in the source region from 2000 to 2019. The results show that the area of desertification in the source region has accounted for 9.36% of the total area, of which the light desertification land is the major portion. The desertification is mainly distributed between the southern margin of Madoi Valley basin and the northern margin of Heihe Valley basin, and is distributed on the river valleys, lakesides, ancient rivers and piedmont proluvial fan, showing the form of patches, sheets and belts. The growth rate of desertification in the source region was 87.47% from 2000 to 2010. With a high growth rate, the process of desertification was represented by the rapid spread of desertification. From 2010 to 2019, the growth rate of desertification was 37.32%, which was relatively slow. But the moderate desertification land maintained a straight linear growth trend, showing an increasing trend of desertification degree. Through the analysis of the driving factors of desertification in the source region of the Yellow River, this paper argues that the special geographical location, climatic factors, rodent damages and human activities are the main causes of desertification.

Marine litter and associated marine pollution are becoming a complex global environmental hazard these days. Among the different faces of marine pollution, by far the largest and probably the most dangerous part is marine plastic litter. Plastic litter can be found in almost every marine environment in the world, including deep ocean beds and frozen polar ice. Unless new sustainable methods of plastic production and waste management are encouraged, marine plastic pollution will continue to pose a severe threat to the natural ecosystems of the world. In this paper, the status of marine plastic litter is reviewed using a DPSIR framework, and it is found that significant changes in the way we live and consume are needed to prevent it. A framework that combines the source-to-sea approach and circular economy is introduced as a possible solution to eliminate plastic waste from the environment as well as from the economy.

This paper explores the macroscopic permeability characteristics, pore distribution, mineral composition, and microstructure changes in remoulded silty clay under different concentrations and different back pressures through flexible-wall triaxial permeability tests, nuclear magnetic resonance tests, X-ray diffraction tests, and scanning electron microscope tests. The results of the flexible-wall triaxial permeability tests indicate that the hydraulic conductivity of the landfill leachate with different concentrations increases to the peak value in 108-132 h period and then decreases to a stable value in 252–264 h period under the action of different back pressures. The nuclear magnetic resonance tests show that the pore distribution of the remoulded silty clay is macropore after it is corroded by the leachate. Increasing the concentration of landfill leachate and reducing the back pressures can reduce the overall development effect of pores. The X-ray diffraction tests show that the weakly acidic corrosive environment provided by remoulded silty clay and landfill leachate reduce respectively the contents of montmorillonite, muscovite, and illite by 33.52 %, 23.57 % and 63.51 %, while kaolinite and albite increase by 283.40 % and 188.64 %. Finally, scanning electron microscope tests show that the corrosion of landfill leachate and the plugging of organic pollutants in the infiltration process reduce the apparent pore ratio of the microstructure of remoulded silty clay and the hydraulic conductivity gradually decreases.

In this study, the microbial population responsible for decomposition of banana leaf with dung and urine of cattle (cow and sheep used here) was isolated, identified, and their incidence calculated. During this study, significant changes were observed in different physio-chemical properties (temperature, pH, moisture content, humidity, ash content, total organic carbon, total nitrogen content, phosphorus) of decomposing material which focuses particularly on the role of thermophilic coprophilous fungi in reducing the time for decomposition. It also gives a clear demonstration of various effects of different environmental conditions on the microbial population during the process of decomposition. The decomposition product thus obtained was found to be rich in organic phosphorous and nitrogen, raising our hopes for a successful implementation of it in daily agricultural practices.

One of the challenges for hydropower dam operation is the occurrence of supersaturated total dissolved gas (TDG) levels that can cause gas bubble disease in downstream fish. Supersaturated TDG is generated when water discharged from a dam entrains air and temporarily encounters higher pressures (e.g. in a plunge pool) where TDG saturation occurs at a higher gas concentration, allowing a greater mass of gas to enter into solution than would otherwise occur at ambient pressures. As the water moves downstream into regions of essentially hydrostatic pressure, the gas concentration of saturation will drop, as a result, the mass of dissolved gas (which may not have substantially changed) will now be at supersaturated conditions. The overall problem arises because the generation of supersaturated TDG at the dam occurs faster than the dissipation of supersaturated TDG in the downstream reach. Because both generation and dissipation of TDG are functions of water temperature, there is an opportunity to affect the TDG process through selective withdrawal structures at a reservoir. Using a combination of field observations, and hydrodynamic modelling, we analysed the dependence of the water temperature difference on TDG generation from different-elevation release structures of highdam reservoirs. By using of the dissipation model coupled with TDG and temperature, the evolution of supersaturated TDG from different withdrawal structures was simulated and compared in a natural river reach. It showed that warmer withdrawals result in reduced generation of TDG and enhanced dissipation of TDG.

Reservoirs play a key role in many infrastructure functions for people like flood control, irrigation, and water supply. In this work, we focused on the water quality evaluation model for Shimen Reservoir. Based on the monthly changes of factors such as pH, nitrate, ammonia nitrogen (NH3-N) and total nitrogen (TN) in 2013 and 2014, the information diffusion theory and fuzzy neural network technology were utilized to evaluate the water quality comprehensively. The probability distribution of these four factors in the reservoir was analysed and the water quality of the reservoir evaluated. The results show its reliability and these two methods can provide a basis for water quality control of Shimen Reservoir. Furthermore, the methods can be universally applied to the analysis and research of water quality in other regions.

This paper presents a summary of PM2.5, PM10 and gaseous pollutant concentrations measured during each season of the year from March 1, 2018 to February 28, 2019 in Visakhapatnam city (17.6868°N, 83.2185°E) located on the east coast of India. The city is studded with 14 major industries and surrounded on three sides by mountains and the Bay of Bengal on the fourth side. The monthly variations of mass concentrations of PM2.5, PM10 and gaseous pollutants SO2, NO2 and CO recorded revealed the impact of atmospheric pollutants originating from industry, urbanization and increased automobile traffic. The seasonal variability of PM concentrations, highest in winter and lowest in summer, is observed. The annual averages for 2018 in Visakhapatnam are 103.5 ± 55.1 ?g/m3 and 111.5 ± 29.1 ?g/m3 for PM2.5 and PM10 respectively. To establish the causal relationship between PM2.5, PM10 and the gaseous pollutants we used Pearson correlation and regression statistical methods. The Pearson correlation coefficients between PMs and gaseous pollutants were either high or moderate. Regression results further confirmed that NO2 and SO2 significantly impacted PM2.5 and PM10 in Visakhapatnam city.

In this research work, the characterization of the palm stearin biodiesel was made using Nuclear Magnetic resonance (NMR), Fourier transform infrared spectroscopy (FITR) and GC/MS methods. Analysis of the composition of fatty acids was done using the GCMS apparatus based on the retention time. Fourier transform infrared spectrometer was used for the spectrum analysis of the various functional groups and bands located in it. The properties of the palm stearin biodiesel were predicted adopting the American Society for Testing and Materials (ASTM) standards. Measured values of the properties were the density at 18°C as 0.88 g/m3, kinematic viscosity at 35°C as 3.4 mm2/s, the calorific value of the palm stearin as 37121 kJ/kg and the flash and fire points of the biodiesel as 130°C and 160oC respectively. The rapid and correct characterization of the palm stearin biodiesel was made by the NMR.