Microbial mediated zinc removal from mine water : a microcosm study

The influence of cyanobacteria mats on the removal of zinc from mine waters and the nature of zinc precipitates were assessed using thirty batch microcosms. The cyanobacteria were isolated from white precipitate mats, composed of hydrozincite (Zn5(CO3)2(OH)6), collected from the Rio Naracauli creek, a stream affected by historical Pb-Zn mining in Sardinia, Italy. The cultured bacteria were inoculated into flasks containing sterilised dead leaves, as a source of carbon, immersed in a solution that simulated mine water with composition of SO4 745 mg/l, HCO3 27 mg/l, Ca 99 mg/l and Zn 300 mg/l. Epifluorescence microscopy showed that the microcosms were able to sustain an active population of bacteria for the duration of the experiment (226 days). Rising pH and falls in dissolved zinc concentrations by 40-60% were interpreted as being indicative of photosynthetic activity and precipitation of zinc from solution. SEM analysis of the particulate matter from the microcosm suspensions showed abundant fibres enriched in Zn and C, typically 10-50um in length. Saturation indices indicated that the microcosm solutions were undersaturated with respect to zinc carbonates, with both low pH and alkalinity limiting precipitation. Cell-surface microenvironments with steep gradients of pH and alkalinity, induced by photosynthesis, could drive localised precipitation of zinc carbonates and, together with absorption onto the cell matrix, account for the observed decrease of zinc in the microcosm solutions. The overall results produce more evidence supporting the role of cyanobacteria for bioremediation of metal contaminated waters. Sequential extraction studies are required to further understand the mobility and subsequent stability of metals associated with this type of microbial mats

Defense contingency contracting handbook, Essential tools, information, and training to meet contingency contracting needs for the 21st century

This handbook provides a pocket-sized guide to help you meet the needs of those whom you are supporting. This is crucial to your success and that of the overall mission. It is by no means a stand-alone document and must be read together with the Federal Acquisition Regulation, the Defense Federal Acquisition Regulation Supplement, and Operational Contract Support in Joint Operations (Joint Publication 4-10)

Tributes to McKenna

245 p. : ill., map ; 26 cm.Includes bibliographical references.Preface / Gina C. Gould and Susan K. Bell ; with contributions from James S. Mellett -- 1. Malcolm C. McKenna : a biography and bibliography / Susan K. Bell -- 2. The ankle structure of two pterodactyloid pterosaurs from the Santana Formation (Lower Cretaceous), Brazil / Alexander W.A. Kellner -- 3. Diversity of early Cretaceous mammals from Victoria, Australia / Thomas H. Rich and Patricia Vickers-Rich -- 4. The anterior dentition of the late Jurassic multituberculate Ctenacodon / George F. Engelmann -- 5. Marsupial mammals from the Albian-Cenomanian (early-late Cretaceous) boundary, Utah / Richard L. Cifelli -- 6. A polydolopine marsupial skull from the Cachapoal Valley, Andean main range, Chile / John J. Flynn and André R. Wyss -- 7. Phylogeny and divergence of basal Glires / Jin Meng -- 8. Adaptation and the origin of rodents / Leigh Van Valen -- 9. Assessing statistical techniques for detecting multispecies samples of heteromyids in the fossil record : a test using extant Dipodomys / Marc A. Carrasco -- 10. The edentulous skull of the North American pangolin, Patriomanis americanus / Robert J. Emry -- 11. Global climate and the evolution of large mammalian carnivores during the later Cenozoic in North America / Robert M. Hunt, Jr. -- 12. New felid material from the Ulaan Tologoi locality, Loh Formation (early Miocene) of Mongolia / Tom Rothwell -- 13. Humeri of Oligoscalops (Proscalopidae, Mammalia) from the Oligocene of Mongolia / Jonathan H. Geisler -- 14. The basicranial and posterior cranial anatomy of the families of the Toxodontia / Sherri L. Gabbert -- 15. Moropus merriami in the early Barstovian Lower Snake Creek fauna of Nebraska, with comments on biogeography of North American chalicotheres / Margery C. Coombs -- 16. A revised dental nomenclature for fossil horses / Robert L. Evander -- 17. Gigantism, dwarfism, and Cope's rule : "Nothing in evolution makes sense without a phylogeny" / Gina C. Gould and Bruce J. MacFadden -- 18. North American mammalian chronostratigraphy : the contributions of Malcolm C. McKenna / Donald R. Prothero