Stability of xanthates in sulfite media

Journal of Mining Science -     

The Effects of Isolation and Acid Mine Drainage on Fish and Macroinvertebrate Communities of Monday Creek, Ohio, USA

Isolated headwater streams in mined watersheds may have good water quality and fish habitat, yet be disconnected from immigration sources by stream segments impaired by acid mine drainage (AMD). Studies of fish and macroinvertebrate communities, habitat, and a number of hydrochemical parameters in Monday Creek, Ohio, show that AMD eliminates fish communities and severely limits macroinvertebrate communities in directly affected tributaries. Isolated headwaters in the heavily mined Monday Creek watershed have relatively good water quality and habitat, but poor fish communities. Comparison of isolated Monday Creek headwaters with non-isolated reaches in unmined watersheds indicates that differences in fish communities are attributable to isolation. Fish communities in isolated headwaters have lower Indices of Biotic Integrity (IBI) than comparable non-isolated communities, reduced species numbers, and lower numbers of individuals, despite suitable habitat as measured by the Qualitative Habitat Evaluation Index (QHEI). Comparison of macroinvertebrate communities shows higher Invertebrate Community Indices (ICI), and no apparent species loss, which can be attributed to the obligate flight stage in the life cycle of many macroinvertebrates, which enables them to overcome aquatic barriers. The implication of this research is that there is an opportunity for recovery of depleted fish communities in large AMD-isolated areas with good water quality, suitable habitat, and intact macroinvertebrate communities, by downstream treatment or source control of AMD to create aquatic corridors for fish immigration.     

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.     

An extension of ASM2d including pH calculation

This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an ion-balance for the calculation of the pH value and the dissociation species. The significant pH variations observed in a sequencing batch reactor operated for enhanced biological phosphorus removal were used to verify the capability of the extended model for predicting the dynamics of pH jointly with concentrations of acetic acid and phosphate. A pH inhibition function for polyphosphate accumulating bacteria has also been included in the model to simulate the behaviour observed. Experimental data obtained in four different experiments (with different sludge retention time and influent phosphorus concentrations) were accurately reproduced.     

Dinoflagellate cysts and hydrographical change in Gullmar Fjord, west coast of Sweden

This high-resolution study of the latest Holocene dinoflagellate cyst record from Gullmar Fjord, on the west coast of Sweden, provides evidence for the recognition of two major dinoflagellate communities within the fjord over the last 85 years. These communities may have their origins with the history of cultural eutrophication within the region, but are more likely to be associated with the wider phenomenon of the North Atlantic Oscillation and/or the complex hydrographical response of the fjord to various changing climatic environments between 1915 and 1999. The changing dinoflagellate cyst populations are compared in detail with the many hydrographical parameters available from this well studied fjord with its long instrumental records. Indeed the dinoflagellate cysts fail to demonstrate a convincing ongoing eutrophication record for the fjord but do show a major change in the cyst assemblages at about 1969/1970 at a time when the NAO was changing from a negative phase to the present-day positive phase. Gullmar Fjord is important in the history of dinoflagellate cyst studies, being the site of the 1954 study by Erdtman in which viable cysts, produced within the phytoplankton, were first documented within the water column.