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The results of a study of soil factors in relation to plant growth for a tropical mangrove forest in northern Australia are presented and discussed. Basic soil properties are described briefly in terms of particle size distribution, bulk density and total carbon, nitrogen and phosphorus. Soil redox potential, pH, salinity and extractable nitrogen and phosphorus were monitored monthly over a 14 month period commencing April 1979. Sampling was carried out at 9 sites along a 370 m transect which exhibits strong gradients in topography, above ground biomass, canopy height and species distribution. Statistical analysis of the data shows that above ground biomass correlates significantly with the following soil factors, averaged over depth within the rooting zone and over time: Extractable P (r=0.85, p<0.01), redox potential (r=0.89, p<0.01) and salinity (r=?0.79, p<0.05). The strong biomass-EH correlation may be partly due to oxygen translocation by the plants to the root zone. Soil ammonium levels were within the range of 1–14 μg N per g (dry wt) and, unlike the above parameters, showed only minor variation with position along the transect. Variation of ammonium levels with time was apparent, but no significant correlation with rate of new shoot growth could be demonstrated, although depth profiles indicated depletion of ammonium by plant uptake during rapid growth periods. In addition neither soil ammonium, extractable phosphorus nor rate of plant growth showed any definite seasonal periodicity in this tropical system. 相似文献
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I.C.A. da Silveira J.A.M. Lima A.C.K. Schmidt W. Ceccopieri A. Sartori C.P.F. Franscisco R.F.C. Fontes 《Dynamics of Atmospheres and Oceans》2008,45(3-4):187
Temporally-growing frontal meandering and occasional eddy-shedding is observed in the Brazil Current (BC) as it flows adjacent to the Brazilian Coast. No study of the dynamics of this phenomenon has been conducted to date in the region between 22° S and 25°S. Within this latitude range, the flow over the intermediate continental slope is marked by a current inversion at a depth that is associated with the Intermediate Western Boundary Current (IWBC). A time series analysis of 10-current-meter mooring data was used to describe a mean vertical profile for the BC-IWBC jet and a typical meander vertical structure. The latter was obtained by an empirical orthogonal function (EOF) analysis that showed a single mode explaining 82% of the total variance. This mode structure decayed sharply with depth, revealing that the meandering is much more vigorous within the BC domain than it is in the IWBC region. As the spectral analysis of the mode amplitude time series revealed no significant periods, we searched for dominant wavelengths. This search was done via a spatial EOF analysis on 51 thermal front patterns derived from digitized AVHRR images. Four modes were statistically significant at the 95% confidence level. Modes 3 and 4, which together explained 18% of the total variance, are associated with 266 and 338-km vorticity waves, respectively. With this new information derived from the data, the [Johns, W.E., 1988. One-dimensional baroclinically unstable waves on the Gulf Stream potential vorticity gradient near Cape Hatteras. Dyn. Atmos. Oceans 11, 323–350] one-dimensional quasi-geostrophic model was applied to the interpolated mean BC-IWBC jet. The results indicated that the BC system is indeed baroclinically unstable and that the wavelengths depicted in the thermal front analysis are associated with the most unstable waves produced by the model. Growth rates were about 0.06 (0.05) days−1for the 266-km (338-km) wave. Moreover, phase speeds for these waves were low compared to the surface BC velocity and may account for remarks in the literature about growing standing or stationary meanders off southeast Brazil. The theoretical vertical structure modes associated with these waves resembled very closely to the one obtained for the current-meter mooring EOF analysis. We interpret this agreement as a confirmation that baroclinic instability is an important mechanism in meander growth in the BC system. 相似文献
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Tiago Carrilho Biló Ilson Carlos Almeida da Silveira Wellington Ceccopieri Belo Belmiro Mendes de Castro Alberto Ricardo Piola 《Ocean Dynamics》2014,64(10):1431-1446
The Brazil Current (BC) is likely the least observed and investigated subtropical western boundary current in the world. This study proposes a simple and systematic methodology to estimate quasi-synoptic cross-sectional speeds of the BC within the Santos Basin (23° S–26° S) based on the dynamic method using several combinations of data: Conductivity, temperature, and depth (CTD), temperature profiles, CTD and vessel-mounted Acoustic Doppler Current Profiler (VMADCP), and temperature profiles and VMADCP. All of the geostrophic estimates agree well with lowered Acoustic Doppler Current Profiler (LADCP) velocity observations and yield volume transports of -5.56 ±1.31 and 2.50 ±1.01 Sv for the BC and the Intermediate Western Boundary Current (IWBC), respectively. The LADCP data revealed that the BC flows southwestward and is ～100 km wide, 500 m deep, and has a volume transport of approximately -5.75 ±1.53 Sv and a maximum speed of 0.59 m s?1. Underneath the BC, the IWBC flows northeastward and has a vertical extent of approximately 1,300 m, a width of ～60 km, a maximum velocity of ～0.22 m s?1, and a volume transport of 4.11 ± 2.01 Sv. Our analysis indicates that in the absence of the observed velocities, the isopycnal (σ 0) of 26.82 kg m?3 (～500 dbar) is an adequate level of no motion for use in geostrophic calculations. Additionally, a simple linear relationship between the temperature and the specific volume anomaly can be used for a reliable first estimate of the BC-IWBC system in temperature-only transects. 相似文献
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Ana Cecília Rizzatti de Albergaria-Barbosa Vinicius Faria Patire Satie Taniguchi Wellington Silva Fernandez June Ferraz Dias Márcia Caruso Bícego 《Marine pollution bulletin》2017,114(1):609-614
This work aimed to evaluate the use of Mugil curema as a biomonitor for polycyclic aromatic hydrocarbon (PAH) bioavailability. Fish biliary metabolites from low-contaminated (Cananéia) and contaminated (Santos) Brazilian estuaries were analysed using a high-performance liquid chromatography apparatus coupled to fluorescence detectors connected in a series. In the Cananéia and Santos estuaries, total metabolite levels ranged from 0.85 to 34.4 μg g? 1 of bile and from 4.06 to 528 μg g? 1 of bile, respectively. Metabolite levels were not influenced by feeding status or sexual hormones (p < 0.05), thus suggesting that M. curema is a good biomonitor for PAH bioavailability. In estuarine regions, it is possible to sample both the male and female genders of this species in any reproductive period. 相似文献
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Sheila M. Palmer Brian I. Wellington Chris E. Johnson Charles T. Driscoll 《水文研究》2005,19(9):1751-1769
Concentrations of both aluminium (Al) and dissolved organic carbon (DOC) in stream waters are likely to be regulated by factors that influence water flowpaths and residence times, and by the nature of the soil horizons through which waters flow. In order to investigate landscape‐scale spatial patterns in streamwater Al and DOC, we sampled seven streams draining the Hubbard Brook valley in central New Hampshire. We observed considerable variation in stream chemistry both within and between headwater watersheds. Across the valley, concentrations of total monomeric aluminium (Alm) ranged from below detection limits (<0·7 µmol l−1) to 22·3 µmol l−1. In general, concentrations of Alm decreased as pH increased downslope. There was a strong relationship between organic monomeric aluminium (Alo) and DOC concentrations (R2 = 0·92). We observed the highest Alm concentrations in: (i) a watershed characterized by a steep narrow drainage basin and shallow soils and (ii) a watershed characterized by exceptionally deep forest floor soils and high concentrations of DOC. Forest floor depth and drainage area together explained much of the variation in ln Alm (R2 = 0·79; N = 45) and ln DOC (R2 = 0·87; N = 45). Linear regression models were moderately successful in predicting ln Alm and ln DOC in streams that were not included in model building. However, when back‐transformed, predicted DOC concentrations were as much as 72% adrift from observed DOC concentrations and Alm concentrations were up to 51% off. This geographic approach to modelling Al and DOC is useful for general prediction, but for more detailed predictions, process‐level biogeochemical models are required. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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B.?K.?LinsleyEmail author G.?M.?Wellington D.?P.?Schrag L.?Ren M.?J.?Salinger A.?W.?Tudhope 《Climate Dynamics》2004,22(1):1-11
In the Pacific Ocean, the coherent pattern of interdecadal variations in sea surface temperature (SST) over the last 100 years has been termed the Interdecadal Pacific Oscillation (IPO). To examine past variations in the IPO we have generated time series of Sr/Ca and oxygen isotopes (18O) from South Pacific Porites coral colonies growing at Rarotonga (1997 to 1726) and Fiji (1997 to 1780). At both sites skeletal Sr/Ca is highly correlated with instrumental SST at least back to 1970 and 18O appears to reflect both SST and South Pacific Convergence Zone (SPCZ) effects on seawater 18O. Comparison of our results to a New Caledonia coral 18O record and to indices of interdecadal Pacific climate variability demonstrates that these South Pacific corals have accurately recorded twentieth century variations in the IPO and SPCZ. The coral records also indicate that higher amplitude and more spatially coherent IPO-related variability existed from 1880 to 1950 with notably poor between-site correlations in the mid-1800s. These observations suggest that the spatial IPO pattern in South Pacific SST was significantly more complex and/or poorly defined in the mid-1800s compared to that observed in the twentieth century. Comparison with North Pacific IPO indices also indicates that the degree of cross-hemispheric symmetry of interdecadal oceanographic variability has changed over time with a lower correlation between the North and South Pacific in the mid-1800s. This evidence suggests that the spatial pattern of the IPO at least in the South Pacific has varied over the last 300 years, with a major reorganization occurring after 1880 A.D. 相似文献
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Magnetic susceptibility of soil: an evaluation of conflicting theories using a national data set 总被引：5，自引：0，他引：5
J. A. Dealing K. L. Hay S. M. J. Baban A. S. Huddleston E. M. H. Wellington P. J. Loveland 《Geophysical Journal International》1996,127(3):728-734
Magnetic susceptibility values for topsoils across England arc combined with data for soil type, geochemistry and concentrations of magnetotactic bacteria in order to evaluate different theories for explaining soil magnetism. Strongly magnetic soils in unpolluted areas are found over weakly magnetic substrates and are dominated by ultrafine superparamagnetic grains. Magnetotactic bacteria are present in insufficient concentrations to account for strongly magnetic soils, and crop burning is discounted as a major factor. A small number of samples show high values associated with either airborne magnetic particulates from pollution or residual primary ferrimagnetic minerals from igneous substrates. The results are used to construct a new mechanism for the formation of secondary ferrimagnetic minerals that links abiological weathering and biological fermentation processes. The fundamental driving force in the mechanism is Fe supply, which may be linked to climate. Observed causative associations between climate and the magnetic susceptibility of loess-palaeosol sequences are supported by the findings. 相似文献
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Kaiser J&#;lia Nogueira Izabel C. M. Campos Ricardo M. Parente Carlos E. Martins Renato P. Belo Wellington C. 《Ocean Dynamics》2022,72(2):137-150
Ocean Dynamics - This paper evaluates the performance of the spectral wave model WAVEWATCH III for the South Atlantic Ocean forced by wind inputs from the most recent reanalyses, NCEP/CFSR and... 相似文献