Sources and Characterisation -- Radioactive Particles Released from Different Nuclear Sources -- Single Particles Handling and Analyses -- Characterisation of DU Particles from Kosovo and Kuwait -- Formation of Radioactive Aerosol Particles During the Wildland Fires in Chernobyl Zone and their Radioecological Impact -- Ecosystem Transfer -- Thule Expedition 2003 - Studies on Radioactive Contamination and Particles -- Hot Particles in the Floodplain of the Yenisei River -- Migration of Fuel Particles of ChNPP Fallout and Leached Radionuclides in Soils and Soil-To-Plant System -- Dissolution of Particles of Irradiated Nuclear Fuel in the Temporary Storages of Radioactive Waste in Chernobyl Zone: Sources for Radionuclides Migration -- Phenomenon of a Fast Migration of Plutonium Radioisotops in Ground Water: Colloids or Soluble Form? -- Restoration of Radiation Events of the Past by Antedated Lakes Bottom Sediment Layers -- 241Ams and 137Cs in Soils of the Belarus Part of the Chernobyl Zone -- Databases, Platforms and Measurement Techniques -- The "Hot Particles" Data Base -- The Experimental Platform in Chernobyl: An International Research Polygon in the Exclusion Zone for Soil and Groundwater Contamination -- Deconvolution of Alpha Spectra From Hot Particles -- The Use of 236U as a Tracer of Irradiated Uranium -- Biological Uptake and Risk Assessment -- Health Effects of Dounreay Hot Particles: A Benchmark for the Evaluation of Doses and Risks -- The Influence of Hot Particle Contamination on Models for Radiation Exposures Via the Aquatic Pathway -- Hot Particles Behavior in Cows After Peroral Intake -- Sources and Types of Uncertainties Associated with Radioactive Particles. Radioactive particles have been released to the environment from a number of sources, including nuclear weapon tests, nuclear accidents and discharges from nuclear installations. Particle characteristics influence the mobility, biological uptake and effects of radionuclides, hence information on these characteristics is essential for assessing environmental impact and risks. This publication presents a series of papers covering sources and source term characterisation, methodologies for characterizing particles, and the impact of particles on the behaviour of radioactive particles in the environment. Sources covered include the Chernobyl accident, nuclear weapons accidents at Thule and Palomares accident, the discharges from Dounreay and Krashnoyarsk, and depleted uranium in Kosovo and Kuwait. The overall aim is that an increased understanding of particle characteristics and behavior will help to reduce some of the uncertainties in environmental impact and risk assessment for particle contaminated areas.