Errors in Measurement and Counting of Particles Using Light Scattering

More efficient air sampling programs can be designed, and clearer interpretations of their data made, if important theoretical aspects are clearly understood. The choice of a sampling time is an important decision affecting the results. Empirical and theoretical calculations show that the averaging effect of sampling time attenuates responses to short period fluctuations in pollutant concentrations. Data for sulfur dioxide concentrations in six cities are examined.

The body acts as a sampling mechanism also, and concentrations inside the body fluctuate less than those outside. These damping processes are quantitatively described. A significant biological parameter is the product of the biological half-life of a pollutant and the fraction of entrance to total resistance for its passage through the body. When sampling time is four times this parameter, attenuation of significant fluctuations is about the same in both samples and the body; when it is twice the parameter, the “sampling window” transmits all significant fluctuations better than the “biological window.” Shorter sampling periods appear to give unnecessary fine detail for biological application according to this theoretical model.     

Climate change impacts in Central Asia and their implications for development

Regional Environmental Change - This paper synthesizes what is known about the physical and biophysical impacts of climate change and their consequences for societies and development under...     

Kosovo-Konflikt: Ökologische Auswirkungen

10 years ago, the WWF (World Wide Fund for Nature) began to support the work of environmental protection in the countries of Eastern Europe. A main topic is the Danube-Carpathian Program. With the beginning of the bombardements, connected with great amounts of chemicals released directly and as clouds from the fires and explosions, the question raises: What are the consequences for mankind and nature? Is there a risk for the Danube-Carpathian Program? The WWF feels responsible for reporting about these consequences. In July 1999, a group of two Oil Experts and two scientists (each a chemist and a toxicologist) visited Belgrad, Pan?evo and Novi Sad, took samples of soil and water, and estimated the contents of dangerous substances. The first findings and the first consequences for nature and human health are described.     

Greenhouse gas fluxes and mitigation potential for managed lands in the Russian Federation

Mitigation and Adaptation Strategies for Global Change - This work aims to assess the dynamics of net greenhouse gas (GHG) emissions and removals, as well as analyse the mitigation potential for...     

Influence of the incorporation of high-and low-density polyethylene granules in mortar matrices on the characteristics of solidified radioactive waste

Granules of high density polyethylene (PEHD) and low density polyethylene (PELD) were used in preparation of the mortar matrices in the immobilization process of radioactive waste materials containing ¹³⁷Cs. The diameter of granulate forms varied from 0.2 to 2.0 mm. Four types of PEHD and PELD, forming four types of matrix materials, were used instead of ordinarily used stone granules of 2 mm average diameter, to decrease the porosity and density of the mortar matrix and avoid the segregation of stone particles on the bottom of the immobilized radioactive waste cylindric form. The physico-chemical characteristics of the radioactive waste mortar mixture form were improved, especially the radionuclide leach-rate. It decreased from 4% for the material prepared with stone granules to 2.5% to 3% for the materials prepared with PEHD and PELD. Mechanical strengths of the mortar-radioactive waste mixture samples prepared with PELD and PEHD were notably higher, 14 to 18 MPa, than the monoliths prepared with the ordinary stone granules, 11 MPa. Using PEHD and PELD as granules in the radioactive waste mortar mixture, the weight of the final, full-sized immobilized monolith was up to 25% lower than material with stone granules.