International Journal of Environmental Research

Article	Citations
Plastic Waste: Challenges and Opportunities to Mitigate Pollution and Effective Management	179
Evaluation of the Climate Change Impact on Urban Heat Island Based on Land Surface Temperature and Geospatial Indicators	57
Role of Endophytes in Abiotic Stress Tolerance: With Special Emphasis on Serendipita indica	40
The Nexus Between Worldwide Governance Indicators and Hydropower Sustainable Growth in EU 28 Region	31
Iron Coated-Sand from Acid Mine Drainage Waste for Being a Catalytic Oxidant Towards Municipal Wastewater Remediation	29
Development of Functionalized Activated Carbon for Uranium Removal from Groundwater	26
Assessing the Driving Factors of Carbon Dioxide and Total Greenhouse Gas Emissions to Maintain Environmental Sustainability in Southeastern Europe	25
A Basin-Scale Groundwater Flow Model of the Columbia Plateau Regional Aquifer System in the Palouse (USA): Insights for Aquifer Vulnerability Assessment	25
GIS-Based Multi-Criteria and Multi-Objective Evaluation for Sustainable Land-Use Planning (Case Study: Qaleh Ganj County, Iran) “Landuse Planning Using MCE and Mola”	24
Cu(II) Removal From Aqueous Solution Using The Walnut Shell: Adsorption Study, Regeneration Study, Plant Scale-Up Design, Economic Feasibility, Statistical, and GA-ANN Modeling	24
Global Warming Status in the African Continent: Sources, Challenges, Policies, and Future Direction	24
Heavy Metal Concentrations in Cynoglossus arel (Bloch & Schneider, 1801) and Sediment in the Chabahar Bay, Iran	23
Heavy Metal Removal from Aqueous Solutions Using Fly-Ash Derived Zeolite NaP1	23
Estimation of Phosphorus Transport Influenced by Climate Change in a Rice Paddy Catchment Using SWAT	22
Biochar Application Rate: Improving Soil Fertility and Linum usitatissimum Growth on an Arsenic and Lead Contaminated Technosol	22
Adsorption of 4-Nitrophenol onto Iron Oxide Bentonite Nanocomposite: Process Optimization, Kinetics, Isotherms and Mechanism	22
Zero-Waste Approach: Assessment of Aluminum-Based Waste as a Photocatalyst for Industrial Wastewater Treatment Ecology	19
Chromium Bioaccumulation by Plants and Grazing Livestock as Affected by the Application of Sewage Irrigation Water: Implications to the Food Chain and Health Risk	18
Optimization of Silica Extraction from Rice Husk Using Response Surface Methodology and Adsorption of Safranin Dye	18
Dynamics of Glyphosate and Aminomethylphosphonic Acid in Soil Under Conventional and Conservation Tillage	18
The System of Self-Consistent of Models: A New Approach to Build Up and Validation of Predictive Models of the Octanol/Water Partition Coefficient for Gold Nanoparticles	17
Insight into Photocatalytic Degradation of Amoxicillin by Biofabricated Granular Zinc Oxide Nanoparticle: Mechanism, Optimization and Toxicity Evaluation	17
Assessment of Surface and Groundwater Resources Quality Close to Municipal Solid Waste Landfill Using Multiple Indicators and Multivariate Statistical Methods	16
Aspirin Adsorption onto Activated Carbon Derived from Spent Tea Leaves: Statistical Optimization and Regeneration Study	15
Testing the Persistence of Shocks on Ecological Footprint and Sub-accounts: Evidence from the Big Ten Emerging Markets	15

Modelling of Streamflow and Water Balance in the Kuttiyadi River Basin Using SWAT and Remote Sensing/GIS Tools	15
Insights in the Aqueous and Adsorbed Photocatalytic Degradation of Carbamazepine by a Biosourced Composite: Kinetics, Mechanisms and DFT Calculations	15
Photocatalytic Degradation of Sugarcane Vinasse Using ZnO Photocatalyst: Operating Parameters, Kinetic Studies, Phytotoxicity Assessments, and Reusability	14
Phytoremediation Potential of E. camaldulensis and M. alba for Copper, Cadmium, and Lead Absorption in Urban Areas of Faisalabad City, Pakistan	14
Agricultural Landscapes in Brandenburg, Germany: An Analysis of Characteristics and Spatial Patterns	14
Intensified Hydrodynamic Cavitation-Based Process for the Production of Liquid Emulsion Membrane (LEM) for the Extraction of Chromium(VI) Ions	13
Effect of Surfactants’ Tail Number on the PVDF/GO/TiO2-Based Nanofiltration Membrane for Dye Rejection and Antifouling Performance Improvement	13
Arsenic Adsorption by TiO2 Nanoparticles Under Conditions Similar to Groundwater: Batch and Column Studies	13
Biosorption of Heavy Metals from Water onto Phenolic Foams Based on Tannins and Lignin Alkaline Liquor	13
A Review on the Potential of Common Disinfection Processes for the Removal of Virus from Wastewater	13
Electro/Fe2+/Persulfate Oxidation of Landfill Leachate Nanofiltration Concentrate Using MMO/TiO2-Ti Anode: A Kinetic Study	13
Effects of Exogenous Organic Matter on the Migration of Organic Contaminants with Different Polarities in Soil	12
System Dynamics Modeling of Water–Energy Nexus for Resource-Saving Policy Assessment	11
Nitrogen Fertilizer Effects on Microbial Respiration, Microbial Biomass, and Carbon Sequestration in a Mediterranean Grassland Ecosystem	11
Green Synthesis of Nano-Zero-Valent Copper for the D-Blue 60 Textile Dye Removal from Aqueous Medium	11
The Review of Ecological Network Indicators in Graph Theory Context: 2014–2021	11
High-Density Polyethylene Waste-Derived Carbon as a Low-Cost Cathode Catalyst in Microbial Fuel Cell	11
The Integration of Carbon Price Between European and Chinese Markets: What are the Implications?	11
Thermal Management of Solar Panels for Overall Efficiency Enhancement Using Different Cooling Techniques	11
Enhanced Electrokinetic Remediation of Cadmium (Cd)-Contaminated Soil with Interval Power Breaking	10
Overview of Air Pollution in Typical Basin of China Under the Target of Carbon Neutrality	10
Synthesis of Novel Hybrid NF/FO Nanocomposite Membrane by Incorporating Black TiO2 Nanoparticles for Highly Efficient Heavy Metals Removal	10
Scale-up Design and Treatment Cost Analysis for Abatement of Hexavalent Chromium and Metanil Yellow Dye from Aqueous Solution Using Mixed Phase CaFe2O4 and ZrO2 Nanocomposite	10
The Impact of Biomass Energy Consumption on CO2 Emission and Ecological Footprint: The Evidence from BRICS Countries	9
Invasion Intensity Modulates the Allelopathic Impact of Solidago canadensis L. Leaves and Roots Against Lactuca sativa L. During Germination and Early Seedling Stage	9
Unraveling Microbes as Potential Proxies for Remediation of Heavy Metal and Pesticide Contamination: A State-of-the Art Review	9
Contradictory Results of Soil Greenhouse Gas Emissions as Affected by Biochar Application: Special Focus on Alkaline Soils	9
Microplastic Composition, Load and Removal Efficiency from Wastewater Treatment Plants Discharging into Orontes River	9
Application of Waste-Derived Activated Red Mud/Base Treated Rice Husk Composite in Sulfate Adsorption from Aqueous Solution	8
Behaviors and Mechanism of Color, COD, and Silica Removals in the Electrocoagulation of Batik Wastewater Using Waste Aluminum Electrodes	8
Comparative Analysis on Metal Removal Potential of Exopolymeric Substances with Live and Dead Cells of Bacteria	8
Toxicity, Environmental Monitoring and Removal Strategies of Arsenic	8
Radioactive Cs Removal from Aqueous Solutions by Biochar-Immobilized Potassium Nickel Hexacyanoferrate Prepared Using Ball Mill	8
Air Pollution and Health Impacts of Atmospheric PM: Application of AirQ+ Model to Jiangsu Province in China	8
Valorization of Rice Husk to Value-Added Chemicals and Functional Materials	8
Use of Slaughterhouse Sludge in the Bioremediation of an Oxyfluorfen-Polluted Soil	8
Micro- and Nanoplastics in Environment: Degradation, Detection, and Ecological Impact	8
Recycling of Rice Husk for Preparation of Activated Carbon/Magnetite Nanocomposites for Removal of Methylene Blue from Wastewater	8
Removal of Phosphate from the Healthcare Wastewater Through Peroxi-Photoelectrocoagulation Process: Effect of Process Parameters	8
Improving the ARIMA Model Prediction for Water Quality Parameters of Urban Water Distribution Networks (Case Study: CANARY Dataset)	8
Understanding the Impact of Soil Clay Mineralogy on the Adsorption Behavior of Zinc	8
Human Health Risk Assessment of Mercury in Soil–Plants System	7
Improvement of Sludge Dewatering by Ultrasonic Pretreatment	7
Groundwater Monitoring Network Design Using Optimized DRASTIC Method and Capture Zone Analysis	7
Spatial and Temporal Changes in Hydrological Regionalization of Lowland Rivers	7
Box-Behnken Response Surface Design for Modeling and Optimization of Electrocoagulation for Treating Real Textile wastewater	7
Effectiveness of Fe, Mn, UV254 and Colour Removal from Pre-ozonated Groundwater Using Anthracite Coal	7
Sorption of Cadmium, Lead, Arsenate, and Phosphate on Red Mud Combined with Phosphogypsum	7
Facile Synthesis of ZnO/g-C3N4 with Enhanced Photocatalytic Performance for the Reduction of Cr(VI) in Presence of EDTA Under Visible Light Irradiation	7
Remediation of Fluoride from Groundwater Using Modified Pineapple Juice Extracted Residue	7

Yttrium Doped Bismuth Vanadate Titania Heterojunction for Efficient Photoreduction of Cr from Wastewater Under Visible Light	7
Nitrate Removal by Sorbent Derived from Waste Lignocellulosic Biomass of Lagenaria vulgaris: Kinetics, Equilibrium and Thermodynamics	6
Reliability of the Mass Transfer Factor Models to Describe the Adsorption of NH4+ by Granular Activated Carbon	6
Impact of Climate Change on Cocoa Production in Africa: An Approach of Cross-sectional ARDL	6
Multi-objective Optimization Method Based on Deterministic and Metaheuristic Approaches in Water–Energy–Food Nexus Under Uncertainty	6
Variation of the Gravimetric Composition of Landfilled Municipal Solid Waste Over the Time in a Developing Country	6
Assessment of Cadmium (Cd) in Paddy Soil and Ditch Sediment in Polluted Watershed and Non-Polluted Watershed	6
Brassica juncea as a Feasible Hyperaccumulator of Chosen Potentially Toxic Metals Under Extreme Environmental Conditions	6
Application of Continuous Column Adsorption of Organochlorine Pesticides from Contaminated Water onto Date Stones Activated Carbon	6
Simultaneous Ecosystem Benefit and Climate Change Control: A Future Study on Sustainable Development in Iran	6
Particle-Size-Dependent Filtration Efficiency, Breathability, and Flow Resistance of Face Coverings and Common Household Fabrics Used for Face Masks During the COVID-19 Pandemic	6
Kinetics and Adsorption Isotherm of Strontium on Sugarcane Biochar and Its Application in Polluted Soil	6
Applications of Bioflocculants for Heavy Metals Removal: A Systematic Review	6
Modeling and Optimization by RSM for the Removal of the Dye "Palanil blue R” by Coagulation-Flocculation Process	6
Duckweed-lemna minor as green route for removal of chromium (VI) from aqueous solution	6
Hexavalent Chromium Removal Using Ionic Liquid Coated Magnetic Nano Zero-Valent Iron Biosynthesized by Camellia sinensis Extract	6
Preparation of new h-MoO3 rod-like microcrystals for effective removal of cationic dye in aqueous solution	6
Phosphorus Removal and Recovery During Microalgae-Based Wastewater Treatment: A Mini-review	6
A Mobile Vehicle-Based Methodology for Dynamic Microclimate Analysis	6
Impact of Land Use and Land Cover Change on Ecosystem Services in Eastern Coast of India	6
Adsorption Activity of Spent Coffee Grounds Biochar for the Removal of Vivizole Red 3BS Dye from Aqueous Solution	6
The Ecotoxicity of Sugarcane Pesticides to Non-target Soil Organisms as a Function of Soil Properties and Moisture Conditions	6
Synthesis and Characterization of Nano-CoFe2O4 Ferrite: Application to the Adsorption of AG25 Dye in Aqueous Solution	5
The Impact of COVID-19 Outbreak on Camping Tourism in Spain: A Spatial Approach to Tourist Destinations	5
Energy and Carbon Footprints for the Urban Water Cycle in Amman, Jordan	5
Assessing the adverse effects of a mixture of AMD and sewage effluent on a sub-tropical dam situated in a nature conservation area using a modified pollution index	5
Mitigation Approaches to Prevent Microplastics Effects in the Aquatic Environment: Exploration of Microbeads from Personal Care and Cosmetic Products	5
The Efficiency of Volcanic Tuff-Based Foamed Geopolymer for Heavy Metals Removal: A Parametric Study	5
Sequential Fe2O3-Powdered Activated Carbon/Activated Sludge Process for the Removal of Reactive Black 5 and Chemical Oxygen Demand from Simulated Textile Wastewater	5
Characterization and Ethanol-Sensing Behavior of Nanostructured Vanadium Pentoxide Recovered from Oil Fly Ash	5
An Excellent Alternative to Industrial Activated Carbons for the Purification of Textile Water Elaborated from Waste Coffee Grounds	5
Production of Waste Tomato Stem Hydrochar (TS-HC) in Subcritical Water Medium and Application in Real Textile Wastewater using Photocatalytic Treatment System	5
The Effects of Urbanization on Reduction of Groundwater Level and Changes in Vegetation and Surface Temperature in Iran’s Desert Areas (Case Study: Yazd Province)	5
Modelling and Optimization of Biochar-Based Adsorbent Derived from Wheat Straw Using Response Surface Methodology on Adsorption of Pb2+	5
Predicting Wildfires Occurrences Using Meteorological Parameters	5
Degradation of Sulfadiazine by Activated Peroxymonosulfate on Biochar with Different Carbon Structures	5
Gross Alpha and Beta Radioactivity Evaluation in Drinking Water: Results from the Calabria Region, Southern Italy	5
Algae for Wastewater Treatment and Production of Biofuels and Bioproducts	5
The Economic Valuation of Ecosystem Services: Economic Value-Based Management in a Case Study of Protected Areas in Iran	4
The Effects of Washing Techniques on Thermal Combustion Properties of Sewage Sludge Chars	4
Analysis of Worldwide Greenhouse and Carbon Monoxide Gas Emissions: Which Countries Exhibit a Special Pattern? A Closer Look via Twitter	4
Impact of Silicon and Heavy Metals on Hemp (Cannabis sativa L.) Bast Fibres Properties: An Industrial and Agricultural Perspective	4
Satellite-Based Monitoring of the Algal Communities of Aras Dam Reservoir: Meteorological Dependence Analysis and the Footprint of COVID-19 Pandemic Lockdown on the Eutrophication Status	4
Non-carcinogenic risk assessment of Cr and Pb in vegetables grown in the industrial area in the southwest of Iran using Monte Carlo Simulation approach	4
The Potential of Oil Palm Frond Biochar for the Adsorption of Residual Pollutants from Real Latex Industrial Wastewater	4
Potential of Fish Scale Biochar Nanocomposite with ZnO for Effective Sequestration of Cr (VI) from Water: Modeling and Kinetics	4
Effects of Shallow Water Table Depth on Vegetative Filter Strips Retarding Transport of Nonpoint Source Pollution in Controlled Flume Experiments	4
Comparison of Different Anodes and Investigation of Energy Consumption in the Treatment of Real Wastewater by Electrooxidation	4
Investigation of SARS-CoV-2 Genome in the Indoor Air and High-Touch Surfaces	4
Investigating Visual Aesthetic Fatigue in Urban Green Spaces	4
Optimal and Fair Distribution of Water Under Water Scarcity Scenarios at a Macroscopic Level	4
Consequences of Coastal Wetlands Reclamation and the Need for Integrating Impact Assessment of Invasive Alien Plants Species and Coastal Armoring in Life Cycle Assessment (LCA)	4
Biogas Production from Co-digestion Between Rice Straw and Food Waste with Pilot Scale	4
Selective Decolorization of Methylene Blue from Methyl Orange in Heterogeneous Fenton-like Reaction	4
Assessment of CO2 Emission and Decarbonization Measures in Uzbekistan	4
Characterization and Efficiency Evaluation of Cold Active Bacterial Isolates for Treatment of Sanitary Landfill Leachate	4
Use of Helix aspersa and Pinus nigra as Bioindicators to Study Temporal Air Pollution in Northern Lebanon	4
Analyzing and Evaluating Industrial Ecology Development Model in Iran Using FAHP-DPSIR	4
Analysis of the Gridded Influencing Factors of the PM2.5 Concentration in Sichuan Province Based on a Stacked Machine Learning Model	4
Numerical and Experimental Investigation on Enhancing Thermal Conductivity of Paraffin Wax with Expanded Graphene in Battery Thermal Management System	4
An Overview of Characterisation, Utilisation, and Leachate Analysis of Clinical Waste Incineration Ash	4
Pyrolysis of Coconut Inflorescence Wastes: Production, Effects of Parameters, Characterization and Optimization of Phenolic-Rich Bio-Oil	4
Characterization of High-Performance Zinc Chloride Activated Biochar Modified by Thermal Chemical Vapor Deposition (CVD) and Its Removal Mechanism of Aqueous Nitrate Ions	3
Robust Flood Risk Management Strategies Through Bayesian Estimation and Multi-objective Optimization	3
Impact of COVID-19 on Management, Quality and Satisfaction of Health Organizations: A Case Study in a Portuguese Hospital	3
Pavement Performance Enhancement Using Waste Rubber: Green Pavement Design for Kuwait	3
Treatment of 17α-Ethinylestradiol (EE2) in Water Using UV/H2O2 and Reverse Osmosis (RO) Membranes: Assessment of Estrogenic Activity and Membrane Adsorption	3
Effect of ZnO Nanoparticles During the Process of Phytoremediation of Soil Contaminated with As and Pb Cultivated with Sunflower (Helianthus annuus L.)	3
Chemometric Optimization of a Demineralization Method for Analysing Sediment Organic Matter by Fourier Transform Infrared Spectroscopy	3
Microbial Degradation of Explosive Manufacturing Facility Wastewater in a Bioreactor	3
The interactions between habitat, sex, biomass and leaf traits of different willow (Salix) genotypes	3
Fabrication of Silver–2–Aminoterephthalic Acid Coordination Polymer‐Coated Fe3O4 for Effective Removal of Lead from Aqueous Media	3
Effects of Considering Social Costs in Different Economic Scenarios of Water Systems in Iran	3
Optimal Design of Ecological Concrete Mix Proportion Based on AHP-GWO-BP Neural Network	3
Simulation of Chlorine Injection in Water Distribution Networks in Response to Contaminations	3
Assessment of Carbon Reserves and Biomass of Forest Ecosystems in the Southern Urals	3
Adaptation of Environmental Assessment to PSS Specificities: Heating Appliance Case Study	3
The Efficiency of Different Digestion and Separation Methods for Extracting Microplastics in Typical Organic Solid Waste	3
Profile, Sources, Ecological and Health Risk Assessment of PAHs in Agricultural Soil in a Pljevlja Municipality	3
Magnetic MgAl-LDH for Adsorptive Removal of Malachite Green from Water	3

Porous Materials Prepared by Magnesium Phosphate Cement for the Effective Immobilization of Lead Ions	3
Enhancement in Ni–Cd Phytoremediation Efficiency of Helianthus annuus L. from Battery Waste Contaminated Soil by Bacterial Augmentation, Isolated from E-Waste Contaminated Sites	3
Decadal Changes in Atmospheric Methane Emissions in the Eastern Himalayan Region: Source Apportionment and Impact Assessment	3
Forecasting Effluent Biochemical Oxygen Demand in Sewage Treatment Plants Using Machine Learning and User-Friendly Interface	3
Vertical Distribution of Phosphorous Fractions and Bioavailability of the Nutrient in the Southern Indian Ocean	3
Current Status, Emerging Challenges, and Future Prospects of Industrial Symbiosis in Africa	3
Persistence of Sulfur Dioxide Emissions in OECD Countries Between 1750–2014: A Fractional Integration Approach	3
Treatment of Winery Wastewater with PEG-600/PVDF Mixed Matrix Membranes Using Submerged Membrane Bioreactor and Process Optimization by Box–Behnken Design	3
Mathematical Modeling of Thin-Layer Solar Drying of Poultry Abattoir Sludge	3
Performance Evaluation of Machine Learning Algorithms in Change Detection and Change Prediction of a Watershed’s Land Use and Land Cover	3
Determining the Most Sensitive Indicators of Soil Carbon Transformation to the Land-Use Change from Intact Rangeland to Cropland, Western Iran	2
Short-Term Effects of Operating Parameters and Wastewater Constituents on the Performance of Free-cell Candidatus Brocadia and Candidatus Scalindua Anammox Enrichment	2
Adsorption rate and capacity assessment of Methylene blue removal by biocomposite microparticles using design of experiments	2
Biochar Promotes the Germination and Growth of Herbaceous Seeds Hydroseeded on Gold Mine Tailings	2
Sulfate Radical-Based Advanced Oxidation Technology to Remove Pesticides From Water A Review of the Most Recent Technologies	2
Treatment of Reactive Dye Hydrolysates with UV-C- and Ozone-Activated Percarbonate and Persulfate	2
Monitoring of the Physicochemical Parameters During the Co-Composting of Dehydrated Faecal Sludge and Organic Household Solid Waste: Composts Maturity Assessment	2
Magnetic Nanocomposite of TiO2 as Efficient Adsorbent for Direct Green 26 Dye: Multivariate Optimization, Kinetic and Equilibrium Isotherms	2
A Sustainable Green Approach for Efficient Capture of Strontium from Simulated Radioactive Wastewater Using Modified Biochar	2
Scaling-up Studies on Electrolysis Using Cation Exchange Membrane for Alum Recovery	2
The Influence of Oil Pollutants on the Mechanical Properties of Clayey Sand	2
Immobilization of Cells of Hydrocarbon-oxidizing Bacteria for Petroleum Bioremediation Using New Materials	2
Trace Elements in Fluvisols with Different Anthropogenic Load	2
Carbon Stock Profiling of Mangrove Ecosystem in the Semarang-Demak Coastal Area for Global Warming Mitigation	2
Nitrate-Induced Toxicity and Potential Attenuation of Behavioural and Stress Biomarkers in Tubifex tubifex	2
Biostimulation of the In Situ Production of Biosurfactants During the Bioremediation of Diesel Oil in Clayey Soil	2
Fluoride Removal from Aqueous Solution Employing Chicken Feathers: Isotherms, Kinetics and Thermodynamics Studies	2
Degradation of Municipal Solid Waste Landfill Leachate Using Ferrites from Spent Batteries as Heterogeneous Solar Photo-Fenton Catalyst	2
Synthesis and Characterization of Laccase Enzyme Aggregates From Trametes villosa for Simultaneous Elimination of Rifampicin and Isoniazid	2
Survey of Low Birthweight and Extremely Low Birthweight Events in a High Environmental Risk Area of Apulia, Italy	2
Indigenous PGPB Inoculant from Qinghai-Tibetan Plateau Soil Confer Drought-Stress Tolerance to Local Grass Poa annua	2
Comparative Study of Algae and Cactus as Bioflocculants in the Physico-chemical Treatment of Leachate from the Controlled Landfill	2
Real-Time Size Distributions of Air Pollutants From a Wastewater Treatment Plant in the New York State Capital District	2
Health Risk Assessment Related to As, Cd and Pb Due to the Consumption of Shrimp Species from Southeast Brazil	2
Removal of Pharmaceuticals from Aqueous Solutions by Photodegradation Using TiO2 and Sn/Zn/Fe-Doped TiO2 as Photocatalyst Under Ultraviolet and Visible Light	2
Application for Reprocessing Cattle, Chicken, and Fish Bones in the Removal of Zn (II) and Cr (VI) from Wastewater Using Batch Adsorption System	2
Carbon-Based Catalysts for Clean Environmental Remediation	2
Impact Analysis of Internalizing Environmental Costs on Technical, Economic, and Environmental Performances for Power Plants	2
Role and Concept of Rooftop Disconnection in Terms of Runoff Volume and Flood Peak Quantity	2
Spread of Multidrug-Resistant Bacteria and Antibiotic Resistance Genes in a Swine Wastewater Treatment Plant	2
In Situ Remediation and Stability Assessment of Solid Waste: Alkaline Amendments to Stabilize Acid-Generating High-Concentration Antimony (Sb) Tailings in Southwest China	2