Laboratory and field investigations of particulate and carbon monoxide emissions from traditional and improved cookstoves

We implemented a program in which emission characterization is enabled through collaborations between academic, US and international non-governmental entities that focus on evaluation, dissemination, and in-use testing, of improved cookstoves. This effort resulted in a study of field and laboratory emissions from traditional and improved biofuel cookstoves. We found that field measured particulate emissions of actual cooking average three times those measured during simulated cooking in the laboratory. Emission factors are highly dependent on the care and skill of the operator and the resulting combustion; these do not appear to be accurately reproduced in laboratory settings. The single scattering albedo (SSA) of the emissions was very low in both lab and field measurements, averaging about 0.3 for lab tests and around 0.5 for field tests, indicating that the primary particles are climate warming. Over the course of three summers in Honduras, we measured field emissions from traditional cookstoves, relatively new improved cookstoves, and “broken-in” improved cookstoves. We found that well-designed improved cookstoves can significantly reduce PM and CO emission factors below traditional cookstoves. For improved stoves, the presence of a chimney generally resulted in lower emission factors but left the SSA unaffected. Traditional cookstoves had an average PM emission factor of 8.2 g kg^?1 – significantly larger than previous studies. Particulate emission factors for improved cookstoves without and with chimneys averaged about 6.6 g kg^?1 and 4.5 g kg^?1, respectively. The elemental carbon (EC) fraction of PM varied significantly between individual tests, but averaged about 25% for each of the categories.     

Organo-tins in sediments and mussels from the Sado estuarine system (Portugal)

Analyses of methyl- and butyl-tin levels in freshwater, estuarine and marine sediments from the Sado estuarine system, and in mussels (Mytilus galloprovincialis) from its adjacent coast, have been performed in order to detect the contaminated areas. The main inputs of tributyl-tin (TBT), along with degradation products di- and monobutyl-tin (DBT and MBT), were detected in the estuarine zone, due to high discharge from shipyards located in this area. These levels are sometimes very high, ranging from 235 to 12,200 ng g(-1) total butyl-tins in sediments. Such inputs lead to higher bioconcentration values in mussels in the estuarine zone, as well as in a harbour located along the adjacent coast. The bioconcentration of organo-tins in mussel tissues could be enhanced in estuarine turbid waters, due to an ingestion of butyl-tins adsorbed onto fine particles, in comparison with non-turbid coastal waters. Debutylation processes occur in both sediments and mussel tissues; in organisms, these processes may lead to the formation of inorganic tin, which may be methylated differently according to the period of the year.