Determination of Free Cd,Cu and Zn Concentrations in Lake Waters by In Situ Diffusion Followed by Column Equilibration Ion-exchange   总被引：1，自引：0，他引：1  

C. Fortin  Y. Couillard  B. Vigneault  P. G. C. Campbell 《Aquatic Geochemistry》2010,16(1):151-172

Combining in situ diffusion and column ion-exchange equilibration, we measured free metal ion concentrations (Cd, Cu and Zn) in water samples collected from the epilimnion of 14 lakes in the Rouyn-Noranda area (600 km north-west of Montreal, QC, Canada). Lakes were selected to represent a wide range of physico-chemical characteristics (hardness, pH, dissolved organic matter—DOM, degree of metal contamination), to determine the influence of these parameters on metal speciation. Total dissolved metal concentrations, as determined within the diffusion cells, varied over one to two orders of magnitude: [Cd] 0.19–2.9 nM; [Cu] 36–190 nM; [Zn] 7–2,800 nM. The proportion of total dissolved metal present as free Cd²⁺ and Zn²⁺ was relatively constant for the 14 selected lakes, despite the wide pH (4.5–8) and DOM (3–23 mg C/L) ranges, probably reflecting the inverse relationship observed between pH and DOM; this proportion did, however, vary with DOM and pH for Cu. Our experimental free metal ion concentrations were compared with those calculated with the thermodynamic models WHAM (Windermere Humic Aqueous Model VI) and ECOSAT 4.7 (incorporating the NICA-Donnan model). Measured and calculated values were in reasonable agreement for both Cd and Zn although measured values were generally slightly higher, i.e. less than one order of magnitude. For several lakes, measured free Cu concentrations were, however, much higher than the calculated values, suggesting that these models overestimate Cu complexation. The gap between measured and calculated free metal ion concentration becomes more important as the total metal concentration decreases and as pH increases.  相似文献   

Diurnal variation in vertical distribution of pelagic copepods off Kaikoura,New Zealand   总被引：2，自引：2，他引：0  

Janet M. Bradford 《新西兰海洋与淡水研究杂志》2013,47(4):337-350

The vertical distribution of 55 species of copepods at levels 0–100 m, 100–250 m, 250–500 m, over 21 hours on 20–21 September 1967 at a station 39 km east of Kaikoura (central east coast), New Zealand, is reported, and changes in the night : day biomass ratio at the three depth levels are discussed.

Most copepod species counted showed diurnal vertical migratory movements generally similar to those recorded by other workers, but differences between sexes were noted. Modifications to the usual diurnal migratory pattern were observed and are thought to be caused by the animal's physiological state or by changes in the environment.

In the surface 250 m, the night : day biomass ratio was >2 but at 250–500 m it was <1.  相似文献   

Summer distribution of the pelagic copepod Centropages aucklandkus in New Zealand waters     

Janet M. Bradford 《新西兰海洋与淡水研究杂志》2013,47(3):287-291

The quantitative distribution of Centropages aucklandicus in summer is described. This coastal species, endemic to New Zealand, is found round the whole country except in the north. It has a northern limit coincident with the 19°c isotherm. Possible factors operating to conserve C. aucklandicus in coastal waters, temperature, salinity, food and behaviour, are discussed.  相似文献   

Phytoplankton biornass in relation to the surface hydrography of southern New Zealand and possible effects on the food chain     

Janet M. Bradford  H. John Cranfield  Keith P. Michael 《新西兰海洋与淡水研究杂志》2013,47(2):133-144

Abstract

The surface distribution of salinity, temperature, nitrate‐nitrogen (N0₃‐N), and chlorophyll a in the southern New Zealand, Foveaux Strait region in February 1977, 1978, 1979, and 1980 was highly variable. The source of new nitrogen appears to be incursions of high‐salinity water west and east of Stewart Island. Although it seems likely that the source of this high‐nutrient, high‐salinity water is vertical, a horizontal advective source cannot be ruled out The chlorophyll a content of surface waters was not related directly to the NO3‐N concentrations. This lower food chain variability may be linked to variability in economically important species. Oysters grew twice as fast in the summer of 1978/79 as they did in 1979/80. But the mean chlorophyll a values were very similar for February of both years (2.5 and 2.2 μg 1^?1, respectively). The elevated NO₃‐N levels in 1979 may have resulted in much higher phytoplankton levels later that summer and resulted in the higher oyster growth rate that year. The mechanisms driving this variability have yet to be determined.  相似文献   

Direct evidence of the South Java Current system in Ombai Strait     

Janet Sprintall  Susan Wijffels  Robert Molcard  Indra Jaya 《Dynamics of Atmospheres and Oceans》2010

Direct velocity measurements from 2004 through 2006 confirm the eastward flowing surface South Java Current (SJC) and its deeper Undercurrent (SJUC) crosses the Savu Sea to reach Ombai Strait, a main outflow portal of the Indonesian Throughflow (ITF). The extension of the South Java Current system into Ombai Strait was hinted at by earlier measurement and modeling studies, but the 3-year velocity time series from two moorings in Ombai Strait clearly show separate distinct cores of flow in the SJC and SJUC. The deeper SJUC is driven by Kelvin waves forced by intraseasonal and semi-annual winds in the equatorial Indian Ocean and, when present, is observed across the entire strait. Eastward flow in the surface SJC is near year-round, although it appears that the mechanisms responsible for this flow differ throughout the year. Both the wind-driven Ekman flow during the northwest monsoon and the strongest semi-annual Kelvin waves that have surface signatures can result in eastward surface layer flow across the entire strait. In contrast, during the southeast monsoon the SJC has a subsurface maximum eastward flow at 50–100 m depth in the northern part of Ombai Strait, while the westward ITF is at an annual maximum at the surface in the southern part of the strait. Surface temperature maps suggest the presence of a front during the southeast monsoon that seems to trap the SJC to within ∼10–15 km of the northern boundary of Ombai Strait. The SJC and the frontal location are related to a complex interplay between local wind-driven Ekman dynamics, the strong ITF flow and topography. Significant energy is found at short intraseasonal time scales (20–60 days) in the along-strait flow that is probably related to the short duration westerly wind bursts that drive the Kelvin waves into Ombai Strait. There is a distinct lack of energy at longer intraseasonal time scales (60–90 days) that is likely attributable to interannual climate variability.  相似文献   

Keeping the stress off the sheep? Agricultural intensification, neoliberalism, and ‘good’ farming in New Zealand     

Julia Haggerty  Hugh Campbell  Carolyn Morris 《Geoforum》2009,40(5):767-329

Under neoliberal schemes like audit systems, consumer demands born of concerns about food safety, the environment and animal welfare are theoretically poised to influence agricultural production systems (Campbell and Le Heron, 2007). Whether such influences might reverse or redirect the trend toward environmentally-damaging rampant productivism of the 20th century hinges in part on the subjective positions of farmers and the ways in which they inform how farmers respond to policy and market signals.In this paper we argue the need for a genuine engagement with both the complexities of farmer subjectivity and the interactions amongst farmer subjectivity and agro-ecologies, and animal bodies in particular. This paper presents a case study of sheep farmers on the South Island that reveals contestation and transitions in traditional markers of “good farming”, particularly animal health. We observe how such transitions arise from reconfigurations of the relationships between agro-ecological, political and social histories. In this paper’s formulation, neither state subsidies nor neoliberalism in agriculture is primary cause or ultimate effect of the transformation of agricultural practice. Rather, changes in the political economy expose contradictions in farmer subjectivities, the resolution of which may block or reinforce trends suggested by the political economy. We suggest that contested ideas about animal health within the social field of pastoral farming in New Zealand makes it possible that New Zealand’s sheep growers may take the high road of best environmental practice via highly audited environmental standards of production demanded by elite consumer markets, or that they may remain in the intensifying trajectory of continuing to drive the sheep’s body to its maximum possible intensity of production. The mixed legacy of neoliberal reform is that it has simultaneously enabled both of these contradictory trajectories in New Zealand pastoralism.  相似文献   

Keck Observations of Solar System Objects: Perspectives for Extremely Large Telescopes     

A. R. Conrad  R. W. Goodrich  R. D. Campbell  W. J. Merline  J. D. Drummond  C. Dumas  B. Carry 《Earth, Moon, and Planets》2009,105(2-4):115-122

From differential tracking techniques, required for appulse observations of KBOs with Laser Guide Star Adaptive Optics (LGSAO), to developing methods for collecting spectra at the precise moment of a predicted impact, each Solar System observation conducted on a large telescope presents a unique set of challenges. We present operational details and some key science results from our science program, adaptive optics observations of main belt asteroids and near earth objects; as well as the technical and operational details of several Keck Solar System observations conducted by other teams: the impact of Shoemaker-Levy 9 on Jupiter, volcanoes on Io, the Deep Impact mission to Comet 9P/Tempel 1, and recent observations of Pluto’s moons Nix and Hydra. For each of these observations, we draw from our Keck experience to predict what challenges may lie ahead when similar observations are conducted on next generation telescopes.  相似文献   

The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures     

D. Heath Jones  Mike A. Read  Will Saunders  Matthew Colless  Tom Jarrett  Quentin A. Parker  Anthony P. Fairall †  Thomas Mauch  Elaine M. Sadler  Fred G. Watson  Donna Burton  Lachlan A. Campbell  Paul Cass  Scott M. Croom  John Dawe †  Kristin Fiegert  Leela Frankcombe  Malcolm Hartley  John Huchra  Dionne James  Emma Kirby  Ofer Lahav  John Lucey  Gary A. Mamon  Lesa Moore  Bruce A. Peterson  Sayuri Prior  Dominique Proust  Ken Russell  Vicky Safouris  Ken-ichi Wakamatsu  Eduard Westra  Mary Williams 《Monthly notices of the Royal Astronomical Society》2009,399(2):683-698

We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky  (| b | > 10°)  . Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with  ( K , H , J , r _F, b _J) ≤ (12.65, 12.95, 13.75, 15.60, 16.75)  . The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with   z ≤ 0.1  , showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS .  相似文献   

A GEOGRAPHICAL ANALYSIS OF IMAGE INTERPRETATION METHODS     

James B. Campbell 《The Professional geographer》1978,30(3):264-269

Image interpretation methods, procedures for relating image pattern to ground conditions, are essential to our use of remote sensing imagery. These methods can be analyzed in respect to the role of ancillary information in the image interpretation process. In general, those procedures that are comparatively independent of ancillary information can be applied in varied geographic settings. Because almost all interpretation procedures depend to some extent upon ancillary information, a detailed and integrated knowledge of the cultural and physical landscape is a prerequisite for both manual and automated interpretation procedures.  相似文献   

THE COLONY METEORITE AND VARIATIONS IN CO3 CHONDRITE PROPERTIES     

Alan E. Rubin  Janet A. James  Bradley D. Keck  Karen S. Weeks  Derek W.G. Sears  Eugene Jarosewich 《Meteoritics & planetary science》1985,20(2):175-196

The Colony meteorite is an accretionary breccia containing several millimeter-to centimeter-size chondritic clasts embedded in a chondritic host. Colony is one of the least equilibrated CO3 chondrites; it has an unrecrystallized texture and contains compositionally heterogeneous olivine and low-Ca pyroxene, kamacite with low Ni and Co and high Cr, amoeboid inclusions with low FeO and MnO, a fine-grained silicate matrix with very high FeO, and numerous small chondrules with clear pink glass. However, Colony differs from normal CO chondrites in several respects: Although Al, Sc, V, Cr, Ir, Fe, Au and Ga abundances are consistent with a CO chondrite classification, certain lithophiles (Mg and Mn), siderophiles (Ni and Co) and chalcophiles (Se and Zn) are depleted by factors of 10–40%. The shape of Colony's thermoluminescence (TL) glow curve is similar to that of Allan Hills A77307 (another unequilibrated chondrite with CO3 petrological characteristics) and different from those of normal CO chondrites. [ALHA77307 also resembles Colony in having low Mg, Mn, Ni and Co, compared to normal CO chondrites, but it possesses CO-CV levels of Se and Zn and nearly CV levels of Cd.] Colony is badly weathered; it contains 22.7 wt.% Fe₂O₃ and 5.7 wt.% H₂O. Recalculating the analysis on an H₂O-free basis with all Fe₂O₃, NiO and CoO converted to metal, yields an inferred original metallic Fe, Ni abundance of ～ 19 wt.%. This is similar to that of Kainsaz (an unweathered CO3 fall), but much higher than that of all other CO3 chondrites (< 6.3 wt.%). Although it is possible that Colony and either ALHA77307 or Kainsaz constitute distinct CO3 chemical subgroups, the weathered nature of Colony and ALHA77307 preclude the drawing of firm conclusions. Nevertheless, it is clear that CO3 chondrites vary more in compositional and petrological properties than was previously recognized.  相似文献