Effects of thinning and understory removal on water use efficiency of Pinus massoniana:evidence from photosynthetic capacity and stable carbon isotope analyses

Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and its key controlling processes are not well understood,which limits our comprehension of the physiological mechanisms of various management practices.In this study,four forest management measures(no thinning:NT;understory removal:UR;light thinning:LT;and heavy thinning:HT)were carried out in Pinus massoniana plantations in a subtropical region of China.Photosynthetic capacity and needle stable carbon isotope composition(δ^(13)C)were measured to assess instantaneous water use efficiency(WUE_(inst))and long-term water use efficiency(WUE_(i)).Multiple regression models and structural equation modelling(SEM)identified the effects of soil properties and physiological performances on WUE_(inst)and WUE_(i).The results show that WUE_(inst)values among the four treatments were insignificant.However,compared with the NT stand(35.8μmol·mol^(-1)),WUE_(i)values significantly increased to 41.7μmol·mol^(-1)in the UR,50.1μmol·mol^(-1)in the LT and 46.6μmol·mol^(-1)in HT treatments,largely explained by photosynthetic capacity and soil water content.Understory removal did not change physiological performance(needle water potential and photosynthetic capacity).Thinning increased the net photosynthetic rate(A_n)but not stomatal conductance(g_s)or predawn needle water potential(ψ_(pd)),implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability.In general,thinning may be an appropriate management measure to promote P.massoniana WUE to cope with seasonal droughts under future extreme climates.

Removal Effect of Precipitation on Atmospheric Particulate Matter (PM_(2.5) ) in Bengbu City

Based on the monitoring data of PM_(2.5) concentration in Bengbu Environmental Monitoring Station and precipitation observation data of Bengbu National Meteorological Observation Station from 2016 to 2019, the influence of precipitation on PM_(2.5) mass concentration in Bengbu City was analyzed. The results show that precipitation had a washing and removal effect on PM_(2.5) in the air, and the removal effect was related to precipitation level, precipitation intensity, precipitation duration and PM_(2.5) concentration. The removal effect of precipitation on PM_(2.5) increased with the increase of precipitation level, and the seasonal difference was obvious. Precipitation intensity was positively correlated with the removal effect of PM_(2.5) , but the average removal rate began to decline when precipitation intensity exceeded 10 mm. With the increase of precipitation intensity, the proportion of positive removal showed an overall upward trend, but there was a low-value area as precipitation intensity was 3-10 mm. Precipitation duration was also positively correlated with the removal effect of PM_(2.5) , and there was a low-value area when precipitation duration was 10-15 h. When PM_(2.5) concentration was low before the precipitation process began, the removal effect was not good, and the average removal rate was negative. As PM_(2.5) concentration was high before the precipitation process started, the removal effect was obvious.

Highly Selective Electrocatalytic CuEDTA Reduction by MoS_(2) Nanosheets for Efficient Pollutant Removal and Simultaneous Electric Power Output

Electrocatalytic reduction of ethylenediamine tetraacetic acid copper(CuEDTA),a typical refractory heavy metal complexation pollutant,is an environmental benign method that operates at mild condition.Unfortunately,the selective reduction of CuEDTA is still a big challenge in cathodic process.In this work,we report a MoS_(2) nanosheet/graphite felt(GF)cathode,which achieves an average Faraday efficiency of 29.6%and specific removal rate(SRR)of 0.042 mol/cm^(2)/h for CuEDTA at−0.65 V vs SCE(saturated calomel electrode),both of which are much higher than those of the commonly reported electrooxidation technology-based removal systems.Moreover,a proofof-concept CuEDTA/Zn battery with Zn anode and MoS_(2)/GF cathode is demonstrated,which has bifunctions of simultaneous CuEDTA removal and energy output.This is one of the pioneer studies on the electrocatalytic reduction of heavy metal complex and CuEDTA/Zn battery,which brings new insights in developing efficient electrocatalytic reduction system for pollution control and energy output.

Nitrogen removal efficiency of iron-carbon micro-electrolysis system treating high nitrate nitrogen organic pharmaceutical wastewater

The nitrate nitrogen removal efficiency of iron-carbon micro-electrolysis system was discussed in treating pharmaceutical wastewater with high nitrogen and refractory organic concentration. The results show that the granularity of fillings,pH,volume ratios of iron-carbon and gas-water,and HRT. have significant effects on the nitrogen removal efficiency of iron-carbon micro-electrolysis system. The iron-carbon micro-electrolysis system has a good removal efficiency of pharmaceutical wastewater with high nitrogen and refractory organic concentration when the influent TN,NH4+-N,NO3--N and BOD5/CODCr are 823 mg/L,30 mg/L,793 mg/L and 0.1,respectively,at the granularity of iron and carbon 0.425 mm,pH 3,iron-carbon ratio 3,gas-water ratio 5,HRT 1.5 h,and the removal rates of TN,NH4+-N and NO3--N achieve 51.5%,70% and 50.94%,respectively.

Dust removal efficiency of high pressure atomization in underground coal mine

To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensively studied in theory by virtue of related theories of hydromechanics and aerosol.According to actual measurements of flow coefficients and atomization angles of X-type swirl nozzle,computational formula was derived for atomized particle sizes of such a nozzle in conjunction with relevant empirical equation. Moreover, a mathematical model for applying high pressure atomization to dust removal in underground coal mine was also established to deduce theoretical computation formula of fractional efficiency. Then, Matlab was adopted to portray the relation curve between fractional efficiency and influence factors. In addition, a theoretical formula was also set up for removal efficiency of respirable dust and total coal dust based on dust size and frequency distribution equations. In the end,impacts of dust characteristic parameters on various dust removal efficiencies were analyzed.

Study on SO_2 Removal Efficiency by Nanosecond Rising Edge Pulse DBD Under Different Environmental Conditions

In this paper, an experimental study on SO2 removal by nanosecond rising edge pulse dielectric barrier discharge （DBD） plasma, generated by multi-needle-to-plane electrodes, is carried out. The mechanism of the effect of various factors, such as gap size between dielectric barrier and discharge needles, environmental humidity, and inlet speed of gas flow upon the removal efficiency of air purification is analyzed. The studies show that SOs removal efficiency improves with the increase in the gap size between dielectric barrier and discharge needles in the case of a fixed space between two electrodes, and also improves with the increase in the environmental humidity. For a mixed gas with a fixed concentration, there is an optimal inlet speed of gas flow, which leads to the best removal efficiency.

Start-up and contaminants removal characteristics of aerobic granules-membrane bioreactor at low temperature

In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and operated at low temperature using the carbon resource of sodium acetate. Aerobic granules cultivated in AGS-MBR possess smooth surface and compact structure in morphology as well as better settling property and higher biomass after 38 days. The average parameters of aerobic granules are: diameter 3. 1 mm,wet density 1. 041 g/mL,sludge volume index 42. 35 mL/g and settling velocity 20. 6 - 45. 2 cm/min. During the start-up of AGS-MBR,the respectively average contaminants removal efficiencies at low temperature are 91. 9% for chemical oxygen demand (COD) ,89. 2% for NH4 + -N and 86. 3% for PO43- -P,and the overgrowth of filamentous bacteria has been well controlled. In addition,the hollow fiber microfiltration (MF) membrane fouling is light and the regime membrane layer is capable of enhancing membrane filtration as well as the average growth of trans-membrane pressure (TMP) is 1. 07 kPa/d. Compared with the conventional cultivation of aerobic granules,the sludge granulation time significantly decreases from 73 days to 38 days by the application of microfiltration membrane at low temperature.

A Fast Predicting Neural Fuzzy Model for Suspended Solid Removal Efficiency in Multimedia Filter

Modeling of filter performance is very difficult because of complexity of the defining physical and chemical events in the filtration system whereas the knowledge of functionality of filter coefficient. The main objective of this study is to predict the performance of multimedia filter and to evaluate both the initial and transient stage of suspended solid removal efficiency depending on experimental data. Fuzzy logic has been used to build a model of multi input and one output (MISO) for the removal efficiency of multimedia filter which it consists from sand and granular activated carbon (GAC) mediums. The control parameters of (FLC) of Sugeno model are seven parameters which are media depths, media grains size for both sand and GAC, filtration rate, diameter of suspension particle, feed concentration, and operation time. The output parameter is removal efficiency of media filter whereas these data are collocated from pilot scale deep bed filter, thus, the removal efficiency of filter was modeled by 575 rules as a function of different control parameters. An adaptive of neuron fuzzy inference system (ANFIS) had used to simulate the experimental data. The simulation results were evaluated using mean absolute percentage error (MAPE), whereas the results showed that the prediction of ANFIS model has a good agreement with experimental data when the MAPE is equal to 7.0458 and fuzzy rule -based modeling proved a reliable and flexible tool to study the performance of multimedia filter. The conclusion showed that there is a relationship between flow rate, effective size and optimum bed depth for all filter media, the increment of effective size generates a higher value of optimum filter bed depth for a lower value of filtration rate. It was concluded that the optimal removal efficiency (95-100) achieved by (0.5-0.7 mm) grain size of sand, (1.5-1.9) mm grain size of granular activated carbon (GAC), with media depths should range from 0.3 to 0.6 m.

A preliminary study on total removal efficiency of organic pollutants in sewage by Harbin municipal sewage treatment plant

To evaluate the removal efficiency of organic pollutants in the sewage by Harbin municipal sewage treatment plant, the influent and effluent samples from the plant were pretreated by liquid-liquid extraction （LLE） under conditions of acidity, neutrality and alkaleseence in sequence, and then were analyzed by gas chromatograph-mass spectrum （GC-MS） procedures. Results indicate that there are 70 species of organic pollutants in the influent sample of the plant, which mainly consist of alkyls, benzene series, esters, and heteroeyclic compounds. Some of these organic pollutants are biotoxie and belong to persistent organic pollutants （POPs）. Four species among them are on the list of Prior Pollutants of Environmental Protection Agency of USA （USEPA）. However, 7 species of organic pollutants appearing in the effluent sample mainly include alkyls of multi-carbons and phthalate esters. The removal efficiency of phthalates is poor because of their poor biodegradability. The sewage treatment technique is effective in removing most＋of organics pollutants.

Water film area and dust removal efficiency of string grilles:a theoretical analysis

Based onmultiphase flowtheory and capillary mechanics,the dimensionless bond number expression of the influence of string grille wire spacing on droplet spreading is derived.Taking a liquid film formed by spreading droplets based on Kelvin correlation,the Young-Laplace equation,and the Hagen-Poiseuille law,an equation for calculating the thickness and height of the liquid film is established with temperature,relative humidity and molar volume of liquid phase as independent variables.According to the theory of string grille filtration and dust removal,a dust removal efficiency calculation model covering the wet string grille wire group is constructed based on the liquid film thickness,height,wire diameter,water film area,and vortex shedding frequency.Finally,a theoretical analysis of the influence of water film area on the efficiency of wet string grille dust removal is carried out based on the spray pressure and the ratio of string grille wire distance to wire diameter.It is found that the effect of spray pressure on water film area and dust removal efficiency is more significant than the string grille wire distance diameter ratio.Moreover,the optimized combination of wet string grille wire distance diameter ratio 0.84,wind speed 3m/s and spray pressure 0.8 MPa is found,which could provide an important reference for engineering applications.

Comparison of heavy metal removal efficiencies in four activated sludge processes

The removal efficiencies of heavy metals(As, Cr, Cu, Ni, Pb and Zn) were investigated in the 17 operating municipal wastewater treatment plants(WWTPs) and compared with those in four main activated sludge processes. Significant differences of heavy metal removal efficiencies were observed among four activated sludge processes. The removal efficiency for As(75.5%) in the oxidation ditch(OD) process is significantly higher than that in the conventional activated sludge(CAS) process(38.6%) or sequencing batch reactor(SBR) process(51.4%). The mean removal efficiencies for Cu and Ni in the OD process are 90.5% and 46.7%, respectively, while low mean removal efficiencies are observed for Cu(69.9%) and Ni(16.5%), respectively, in the SBR process. The removal efficiencies for Cu and Ni in the OD process are significantly higher than those in the anaerobic-anoxic-oxic(A2-O) process. These results highlight the differences of removal efficiencies for heavy metals in different processes and should be considered when selecting a wastewater treatment process.

Degradation of antibiotic contaminants from water by gas–liquid underwater discharge plasma

Antibiotic contamination adversely affects human health and ecological balance.In this study,gasliquid underwater discharge plasma was employed to simultaneously degrade three antibiotics,sulfadiazine(SDZ),tetracycline(TC),and norfloxacin(NOR),to address the growing problem of antibiotic contaminants in water.The effects of various parameters on the antibiotic degradation efficiency were evaluated,including the discharge gas type and flow rate,the initial concentration and pH of the solution,and the discharge voltage.Under the optimum parameter configuration,the average removal rate of the three antibiotics was 54.0% and the energy yield was 8.9 g(kW·h)-1after 5 min treatment;the removal efficiency was 96.5% and the corresponding energy yield was4.0 g(kW·h)-1 after 20 min treatment.Reactive substance capture and determination experiments indicated that ·OH and O3 played a vital role in the decomposition of SDZ and NOR,but the role of reactive substances in TC degradation was relatively less significant.

Numerical Simulation of Dust Removal in the Cyclone Collector of a Straw Crusher Based on a Discrete Phase Model

The cyclone dust collector is an important subsystem of straw crushers used in agriculture.In the present study,a new type of dust collector with involute morphology is proposed to obtain better dust removal efficiency with respect to that of classical tangential and spiral dust collectors.A discrete phase model(DPM)method is used in synergy with a turbulence model,and the SIMPLE algorithm to simulate the flow field inside the dust collector and the related particle dynamics.It is shown that the internal flow field features a primary swirl,a secondary swirl and blockage effects.Moreover,for the involute dust collector,the tangential velocity in the initial stage and the pressure in the high-pressure area are larger than those obtained for the classical types.The dust removal efficiency is 37.11%,25.3%,and 16.37%for the involute type dust collector,the tangential type and the spiral type,respectively.

Efficiency of Removing Sulfur Dioxide in the Air by Non-Thermal Plasma Along with the Application of the Magnetic Field

The non-thermal plasma created by high voltage pulsed power supply can be used to remove sulfur dioxide in the air, but how to increase the removing efficiency is not clear. It is novel to apply the magnetic field in removing SO2 as discussed in this paper. The mechanisms of removing sulfur dioxide by non-thermal plasma along with the application of the magnetic field are analyzed, and the related factors affecting the removal efficiency, such as the magnitude of pulsed voltage, the polarity of the pulse, the layout of the discharge electrode, especially the magnetic field are experimentally investigated. It can be concluded that the purification efficiency is improved significantly by applying the magnetic field.

Study on the Heavy Metals Removal Efficiencies of Constructed Wetlands with Different Substrates

In this study constructed wetlands (CWs) were used to remove three heavy metals (Zn, Cu and Pb). The two tested substrates were made of coke and gravel, respectively. First order dynamic model was appropriate to describe removing of Zn and Cu. The experimental results showed that first dynamic removal rate constants of Zn in CWs with coke and gravel were 0.2326 h-1 and 0.1222 h-1, respectively. And those of Cu in CWs with coke and gravel were 0.2017 h-1 and 0.3739 h-1. However, removal efficiencies of Pb in the coke system and the gravel system were within 95-99%, so the first order dynamic model failed to fit the experimental data because the hydraulic resident times of Pb did not affect outlet concentration of Pb. From the removal rate constants, it is found that the coke and gravel system have different absorption efficiencies of heavy metal pollutants. Therefore, it is suggested that the removal efficiencies of heavy metals are influenced by the choice of substrates to some extent.

Nitrogen Removal Efficiencies for Two Biological Nutrient Removal （BNR） Plants in Thailand： Molasses as an External Carbon Source for Enriched Denitrifying Culture in a BNR Process

Two biological nutrient removal （BNR） wastewater treatment plants （WWTPs） in Thailand were selected for study： the Nonghkaem WWTP and the Suvarnabhumi Airport WWTP. For each site the influents, effluents, and supernatant liquids from anaerobic sludge digesters were analyzed for total Kjeldahl nitrogen （TKN）, total nitrogen （TN）, total chemical oxygen demand （TCOD）, biodegradable chemical oxygen demand （bCOD）, and biochemical oxygen demand （BOD）. Nitrogen removal efficiencies in the Nonghkaem WWTP and the Suvarnabhumi Airport WWTP were evaluated. Inadequate nitrogen removal at the Nonghkaem centralized WWTP was found during the summer period. Influent ratios of bCOD：N at the Nonghkaem plant and the Suvarnabhumi Airport plant were 2.42：1-5.45：1 and 4.1：1-6.5：1, respectively. The efficacy of addition of molasses as a carbon source for enriched denitrifying culture in a BNR process at Nonghkaem was studied. Fluorescent in situ hybridization technique （FISH） was used to identify specific nitrifying bacteria （Nitrosomonas spp., Nitrobacter spp. and Nitrospira spp.）. Nitrospira spp. was the most prevalent species in the aeration tank at the Nonghkaem WWTP. This result from FISH suggests that there were significantly low oxygen and nitrite concentration in the aeration tank at the Nonghkaem WWTP during a period of low nitrogen removal.

Efficient removal of uranium from mice by a novel compound of fullerence multi-macrocyclic polyamine derivatives

Uranium removal efficacy of fullerence multi-macrocyclic polyamine derivatives(C60-MMP),a novel chelating agent,was evaluated in mice.C60-MMP was administrated intravenously into mice at 30 min after the uranium contamination.The molar ratio of chelating ligand/uranium was about 1:1.The results indicate that C60-MMP can effectively prevent accumulation of uranium in liver at 8 h after C60-MMP injection.At 48 h after the last injection,uranium deposition in liver of C60-MMP treated mice is approximately 65%less than that of the control group.C60-MMP reacted positively in promoting the removal of uranium from kidney,and the urinary uranium excretion increased significantly,compared with the control and DTPA-treated mice.However,repeated administration of C60-MMP,and combined injection of DTPA and C60-MMP,did not show desirable effects on uranium removal from mice.It implies that more investigations are needed for the treatment protocols and clinical applications of C60-MMP.

Arsenic Removal from Zimapan Contaminated Water Monitored by the Tyndall Effect

In Zimapan Valley, Mexico, up to 1.1 mg·L-1 of arsenic concentrations have been detected in deep wells that are used as drinking water supply for almost 39,000 people, which could have been exposed to levels higher than 10 μg·L-1 of arsenic, the maximum level recommended by the World Health Organization. Chronic consumption of water contaminated with arsenic can cause several diseases, including cancer. For it, the implementation of practical and economical methods to remove arsenic from drinking water is crucial to protect the population health. In this work, an electrochemical method to remove arsenic from drinking water is described. The process, monitored by Tyndall effect, utilizes Cu2+ and Zn2+ ions from a brass electrode in an electrochemical cell with water as electrolyte. Results show that the EC process reduces the concentration of the arsenic diluted in Zimapan water to a level below the limit of detection of the atomic absorption spectrophotometer employed. Arsenic was removed through the formation of Cu and Zn arsenic compounds. Cu2+ and Zn2+ ions form a hydroxide and eventually polycrystalline precipitation of kottigite and cornubite complexes (identified by energy-dispersive X-ray spectroscopy and X-ray diffraction), which are then filtered to eliminate the precipitated arsenic compounds.

Study on influence of characteristics of air-supply jet on drain-contamination efficiency and air quality in heading

Based on the theory of air supply jet, the conception and theory of the air quality and the drain contamination efficiency, the results achieved by comparing the circular cross section wall jet with the plane wall jet were following: firstly, within the limitation of the ventilation distance at the tunnel heading in a coal mine, there were a better air quality and a higher efficiency of drain contamination with application of the plane wall jet ventilation. Secondly, there was a advantage to improve the air quality of the workers breathing area with mounting the air supply outlet on the top but not on the side of the tunnel heading.