Origin and evolution of formation waters, Alberta Basin, Western Canada sedimentary Basin. I. Chemistry

Inorganic chemical analyses and short-chain aliphatic acid content are used to interpret the origin and compositional evolution of formation waters in the Alberta portion of the Western Canada Sedimentary Basin. Forty-three formation water samples were obtained covering a stratigraphic interval from Devonian to Cretaceous. The data show that: (1) there is a subaerially evaporated brine component that shows no apparent contribution of waters derived from evaporite dissolution; and (2) formation waters have maintained characteristics indicative of subaerially evaporated waters, despite subsequent flushing by gravity-driven meteoric waters in the basin.Formation waters are predominantly Na---Cl brines that contain 4-235g/l total dissolved solids (TDS). Short-chain aliphatic acids (SCA) range up to 932 mg/l, with the following abundance: acetate >> propionate > butyrate. Their number varies randomly with subsurface temperature, depth, geological age and salinity. Instead, SCA distributions appear related to proximity to Jurassic and Mississippian source rocks and to zones of active bacterial SO4 reduction.Based on chemical composition, the formation waters can be divided into three groups. Group I waters are from dominantly carbonate reservoirs and Group II from clastics. Groups I and II are differentiated from Group III in that they are composed of a brine end member, formed by evaporation of sea water beyond the point of halite saturation, that has been subsequently diluted 50-80% by a meteoric water end member. Group III waters are from clastic reservoirs and are dilute, meteoric waters that are decoupled from the more saline, stratigraphically lower, waters of Groups I and II.Group I waters have been influenced by clay mineral transformations in shales surrounding the carbonate reservoirs, ankeritization reactions of reservoir dolomites and calcites, and possible decarboxylation reactions. Group II waters indicate significant leaching reactions, particularly of feldspar and clay minerals. Group I and Group II waters both indicate ion exchange reactions were also possible. The waters are near equilibrium with respect to quartz, calcite, dolomite and barite, but are undersaturated with respect to evaporite minerals (halite, anhydrite). Occurrence of feldspar (predominantly albite) and kaolinite seems to control the population of the water cations. Post-Laramide invasion of meteoric waters provided an impetus for many of the diagenetic reactions in both carbonate, but especially in clastic reservoirs. Subsequent hydrochemical isolation of Group I and II waters from further meteoric influences occurred, resulting in pronounced mixing relations and cross-formational fluid flow replacing the once dominant lateral flow.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28507/1/0000304.pd

Origin and evolution of formation waters, Alberta Basin, Western Canada Sedimentary Basin. II. Isotope systematics and water mixing

Isotopic measurements (Sr, O, D) on formation waters from the Alberta Basin have been made, covering a stratigraphic range from Devonian to Upper Cretaceous. These measurements, combined with chemical compositional trends, give evidence for two distinct water regimes. One hydrological regime is composed of waters hosted in Devonian-Lower Cretaceous reservoirs, the other waters from Upper Cretaceous and younger sedimentary rocks. The two regimes are separated by a regional transgressive shale in the Colorado Group, the Second White Speckled Shale Formation.The waters within the Devonian-Lower Cretaceous regime exhibit a large range in 87Sr/86Sr values (0.7076-0.7129), but have similar Sr concentrations, regardless of host lithology. Bulk rock and late-stage diagenetic cements are less radiogenic than present brines. Importantly, brines from Devonian carbonates possess the most radiogenic Sr isotopic signatures of the waters examined. Devonian shales and/or Cambrian shales may be sources of high 87Sr/86Sr ratios in the carbonate-hosted waters. Waters from the Upper Cretaceous clastic units, which have ratios as low as 0.7058, and diagenetic cements from Upper Cretaceous clastic units appear to have precipitated from fluids similar in Sr isotopic value to modern brines. High Sr concentrations in the Cretaceous clastic waters and sedimentary rocks and correspondingly low 87Sr/86Sr ratios suggest that volcanism in Montana during the Cretaceous may have provided a source of sediments to the study area.Cross-formational upward water migration, superimposed on lateral fluid flow, is required to explain the geochemistry and isotopic systematics in the brines from Devonian-Lower Cretaceous reservoirs. Strontium isotope ratios and Sr contents suggest a two component mixing relation for these waters. This system of waters also exhibits [delta]D values characteristic of meteoric values in the Neogene, reflecting post-Laramide flushing of Tertiary waters throughout the basin, with subsequent hydrochemical isolation from more modern waters. In contrast, waters in Upper Cretaceous reservoirs have O and D isotopic compositions similar to those of present day rainfall; these, in conjunction with very dilute Sr concentrations and low Sr ratios, suggest hydrological isolation from the stratigraphically lower system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28509/1/0000306.pd

Veterinary decision making in relation to metritis - a qualitative approach to understand the background for variation and bias in veterinary medical records

<p>Abstract</p> <p>Background</p> <p>Results of analyses based on veterinary records of animal disease may be prone to variation and bias, because data collection for these registers relies on different observers in different settings as well as different treatment criteria. Understanding the human influence on data collection and the decisions related to this process may help veterinary and agricultural scientists motivate observers (veterinarians and farmers) to work more systematically, which may improve data quality. This study investigates qualitative relations between two types of records: 1) 'diagnostic data' as recordings of metritis scores and 2) 'intervention data' as recordings of medical treatment for metritis and the potential influence on quality of the data.</p> <p>Methods</p> <p>The study is based on observations in veterinary dairy practice combined with semi-structured research interviews of veterinarians working within a herd health concept where metritis diagnosis was described in detail. The observations and interviews were analysed by qualitative research methods to describe differences in the veterinarians' perceptions of metritis diagnosis (scores) and their own decisions related to diagnosis, treatment, and recording.</p> <p>Results</p> <p>The analysis demonstrates how data quality can be affected during the diagnostic procedures, as interaction occurs between diagnostics and decisions about medical treatments. Important findings were when scores lacked consistency within and between observers (variation) and when scores were adjusted to the treatment decision already made by the veterinarian (bias). The study further demonstrates that veterinarians made their decisions at 3 different levels of focus (cow, farm, population). Data quality was influenced by the veterinarians' perceptions of collection procedures, decision making and their different motivations to collect data systematically.</p> <p>Conclusion</p> <p>Both variation and bias were introduced into the data because of veterinarians' different perceptions of and motivations for decision making. Acknowledgement of these findings by researchers, educational institutions and veterinarians in practice may stimulate an effort to improve the quality of field data, as well as raise awareness about the importance of including knowledge about human perceptions when interpreting studies based on field data. Both recognitions may increase the usefulness of both within-herd and between-herd epidemiological analyses.</p

Lymphocytes and macrophages of the epidermis and dermis in lesional psoriatic skin, but not epidermal Langerhans cells, are depleted by treatment with cyclosporin A

Since cyclosporin A (CsA) is an immuno-suppressive agent, its beneficial effect in psoriasis suggests that immune cells may play a role in the pathogenesis and resolution of psoriasis. To determine early effects of CsA in psoriasis, we quantitated immune cells using double immunofluorescence microscopy on biopsy specimens obtained prior to therapy and after 3,7, and 14 days of CsA therapy. CsA therapy resulted in significant reductions in the absolute number of immune cells (including T cells, monocytes/macrophages, and antigen presenting cells) contained within psoriatic skin. The effect was rapid, with over one-half of the reduction in the density of HLe1 + (human leukocyte antigen-1 positive or bone marrow derived) cells, including T cells, activated T cells, monocytes, and Langerhans cells (LCs), occurring within 3 days. Despite the overall reduction in the numbers of immunocytes in the skin, the proportion of T cells, Langerhans cells, and monocytes in relation to the total number of immune cells was unchanged with therapy, reflecting equally proportional losses of each subtype. Dermal CD1 + DR + cells (putative Langerhans cells), which are not found in normal skin but are present in lesional psoriasis skin, were virtually cleared from the papillary dermis after CsA therapy. Although absolute numbers of epidermal Langerhans cells, defined as cells expressing both CD1 (T6) and DR molecules (CD1 + DR + ), were also reduced after CsA, epidermal non-Langerhans CD1 - DR + cells (macrophages, activated T cells, DR - keratinocytes) demonstrated a proportionally greater decrease, with the ratio of CD1 + DR + Langerhans cells/non-Langerhans CD1 - DR + epidermal cells changing from a mean of 0.82 at baseline to 1.92 at day 14. Thus, early in the course of therapy, CsA appears to be effective at clearing CD1 - DR + cells while leaving LC relatively intact in the epidermis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47242/1/403_2004_Article_BF00431054.pd