In conjunction with an environmental assessment of biologically-treated bleached kraft mill effluent (BKME) in a Western Canadian river, data indicated that lipophilic compounds were transferred to the mountain whitefish Prosopium williamsoni through ingestion of filter-feeding benthic caddisflies. P4501A induction was correlated with lipophilic body burdens, not with indices of recent BKME exposure. P4501A contents in hepatic and intestinal tissues of BKME-exposed whitefish were compared during a follow-up collection. Ethoxyresorufin O-deethylase (EROD) activity was not detectable in intestines; P-450 spectral analysis indicated denaturation had occurred. Use of enhanced chemiluminescence (ECL) immunoblotting achieved at least 10-fold greater sensitivity over colorimetric methods and indicated that some intestines did contain P4501A protein. No correlation of intestinal P4501A with hepatic EROD activity or P4501A content was found. Application of the ECL technique significantly improves the analytical detection limits of P4501A immunoblotting. Analysis of historical samples from this site will further probe water-borne versus dietary routes of uptake of BKME-related P4501A inducers in this species. 相似文献
We provide an example of how one estuarine research project engaged regional managers to help guide the research towards the needs of managers and policymakers dealing with shoreline management in the Mid-Atlantic region of the USA. Elements of the approach that contributed to success included a well-targeted initial request for proposals, a review process that included management input both as a review criterion and on the review panel, a careful process in choosing advisory members at the appropriate level in the agencies, regular opportunities for interactions between the management advisory group and the science team, and active involvement of a program manager as liaison throughout the life of the project. Engagement of a management advisory group changed some of the scientific approaches, helped to communicate results, and formed a foundation for incorporation into regional management and initiatives. 相似文献
Reactions and reaction rates within aquifers are fundamental components of critical hydrological processes. However, reactions
simulated in laboratory experiments typically demonstrate rates that are much faster than those observed in the field. Therefore,
it is necessary to conduct more reaction rate analyses in natural settings. This study of geochemical reactions in the regional
aquifer in the Pajarito Plateau near Los Alamos, New Mexico combines modeling with petrographic assessment to further knowledge
and understanding of complex natural hydrologic systems. Groundwater geochemistry shows marked evolution along assumed flow
paths. The flow path chosen for this study was evaluated using inverse mass balance modeling to calculate the mass transfer.
X-ray diffraction and field emission gun scanning electron microscopy were used to identify possible reactants and products.
Considering the mineralogy of the aquifer and saturation indices for the regional water refined initial interpretations. Calculations
yielded dissolution rates for plagioclase on the order of 10−15 mol s−1 m−2 and for K-feldspar on the order of 10−17 mol s−1 m−2, orders of magnitude slower than laboratory rates. While these rates agree with other aquifer studies, they must be considered
in the light of the uncertainty associated with geometric surface area estimates, 14C ages, and aquifer properties. 相似文献
Oil and gas exploration data for the Northern Somalia and Horn of Africa region have been utilised for deep freshwater resources exploration. This unique geophysical and petrophysical dataset is integrated into a regional hydrogeological study and it allows for targeting of unmapped and unknown deep aquifers that would otherwise be beyond the conventional reach of the groundwater sector. The database includes open-hole well logging surveys (resistivity, gamma ray, and spontaneous potential), mud logging and drill stem test (DST) data. The results from the data analysis are combined with the geological interpretation to assess the freshwater potential of each mapped hydrostratigraphic unit in the region. The results highlight the presence of several previously unknown deep low-to-medium salinity (<9 g/L total dissolved solids (TDS)) aquifers within the Jurassic to Eocene units, including the Adigrat, Hamanlei, Gabredarre, Gumburo, Jessoma, and Auradu formations. With tested intervals of water containing less than 3.8 g/L total dissolved solids, the Auradu, Jessoma, and Gumburo formations are the most promising deep freshwater aquifers. Additional results on the analysis of groundwater parameters, such as hydraulic head, provide the basis for further groundwater modelling. The results show that the method has good potential, in particular for use in drought-stricken areas of arid regions. Ultimately, the results from this region have global significance, as the method can provide a new means of boosting fresh groundwater resources in water-poor regions, and supporting sustainable development and utilization of the resources in the medium and long term.
We describe the selection of candidate radio-loud quasars obtained by cross-matching radio source positions from the low-frequency (151-MHz) 7C survey with optical positions from five pairs of EO POSS-I plates scanned with the Cambridge Automatic Plate-measuring Machine (APM). The sky region studied is centred at RA 10h 28m, Dec.+41° and covers ≈0.057 sr. We present VLA observations of the quasar candidates, and tabulate various properties derived from the radio maps. We discuss the selection criteria of the resulting '7CQ' sample of radio-loud quasars. The 70 confirmed quasars, and some fraction of the 36 unconfirmed candidates, constitute a filtered sample with the following selection criteria: 151-MHz flux density S 151>100 mJy; POSS-I E -plate magnitude E ≈ R <20; POSS-I colour ( O E )<1.8; the effective area of the survey drops significantly below S 151≈200 mJy. We argue that the colour criterion excludes few if any quasars, but note, on the basis of recent work by Willott et al., that the E magnitude limit probably excludes more than 50 per cent of the radio-loud quasars. 相似文献