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1.
In 1969–72, nitrate determinations were made on waters from 122 wells on the Waimea Plain, Nelson, South Island, New Zealand. Four wells showed values above 30 mg NO3‐N/litre with a maximum of 50 mg/litre in one well, fifteen were in the 30–20 mg/litre range, forty‐six were between 20 mg and 10 mg/litre; fifty‐seven were below 10 mg/litre, and in only four wells was the nitrate concentration below 1.0 mg NO3‐N/litre. Where it entered the plain, the Wairoa River usually contained about 0.07 mg NO3‐N/litre, whereas the Waiiti River contained from 0.5 to 2.0 mg NO3‐N/litre.

Mapping of gradients of nitrate level indicated that these might contribute to aquifer definition and to sources of replenishing waters.  相似文献   

2.
The method of comparing growth curves that is described in this paper consists of describing growth for the ith group by the equation Li(t) = ai + bi rt, which is linear in the two parameters ai and bi, and subsequently using the analysis of variance to compare the curves. The advantages of the linear growth equation over the von Bertalanffy equation, l i (t) = ai + bi rt i, are easier analysis and a much simpler interpretation of the differences in the parameters in terms of growth rate and maximum size. An example comparing the growth of male and female red gurnard Chelidonichthys kumu from four areas within the Hauraki Gulf is given.  相似文献   

3.
Hydrological data, including current observations, from a line of five stations across seasonal ice in McMurdo Sound, Antarctica, are presented. The observations, which were made during the 1972–73 summer, gave evidence for a net flux of approximately 0.4 × 106m3.s‐1 flowing towards the south to pass under the Ross Ice Shelf. There was a small northward flux (0.04 × 106m3.s‐1) on the western side of the sound, but over most of the width the flow was to the south.

Diurnal tidal currents, which were analysed in terms of K1, P1, and O1 components, were superposed on the drift currents.

Temperature and salinity measurements revealed signs of surface water dilution and warming down to 200 m in the region of southerly drift. Temperatures associated with the northerly drift on the western side of the section were close to freezing at all depths. This water can be identified as coming from under the Ross Ice Shelf.  相似文献   

4.
To distinguish the manner of spread of upwelling effects in the Cook Strait/Taranaki Bight (New Zealand) region, nitrogen uptake and the distribution of nutrients and chlorophyll a are described. NO3 concentrations were closely linked to upwelled water, but this was distributed irregularly and not necessarily with the upwelling focus. NH4, SRP, and chlorophyll a showed varying degrees of association with recycling processes, but linear correlations were not present. NO3 uptake was strongly inhibited by ambient NH4, but not completely. There was no evidence of either N or P limitation of total planktonic biomass, and there was indirect evidence from C/N uptake and cellular ratios that a high growth rate prevailed. N uptake increased with irradiance (= decreasing depth) similar to photosynthesis, but without high light inhibition, and could be related to light by a simple equation. The irregularity of distribution of features suggests that future modelling of the phytoplankton biomass in the region could benefit from analysis of event occurrence rather than of evenly progressive changes.  相似文献   

5.
Tidal currents derived from current meter measurements are compared with the output from a barotropic tidal model of the New Zealand region. For the semi‐diurnal constituents there was very good agreement for the M2 tide and good agreement for the S2 tide. For the diurnal constituents (Kl, Ol) it was found that as the amplitude of the constituents decreased so did both the model/observation agreement and the accuracy of the observed tidal ellipse parameters. Consequently it was not possible to decide whether differences arose through shortcomings in the model or in the data. However, the overall performance of the model as a prognostic tool for ocean tidal current simulation appears to be good.  相似文献   

6.
The CO2 exchange characteristics and chlorophyll content of the pneumatophores of Avicennia marina (Forsk.) Vierh. var. resinifera (Forst.) Bakh. were examined. The results indicate that, in addition to their primary role in ventilation of the buried roots, the aerial roots have the ability to fix exogenous CO2 via photosynthesis. Consequently, during the day these organs are almost auto trophic in terms of carbon balance. When corrected for the respiration of non‐chlorophyllous tissue, they show photosynthetic rates comparable to those of many other woody plants.  相似文献   

7.
Size trends and population characteristics of striped marlin, Tetrapturus audax, caught in the New Zealand recreational fishery were evaluated using club records from the Bay of Islands Sword‐fish Club (BOISC) from 1925 to 2003 (n = 15 114) and biological samples from northern New Zealand collected from 1985 to 1994 (n = 684). Average weight (kg) ± SE of striped marlin declined 6–9 kg every 20 years between 1925 (124.2 ± 1.0 kg) and 2003 (100.1 kg ± 0.4). Weight (H14843 = 444.58, P < 0.001) and condition (H443 = 37.54, P < 0.001) increased significantly throughout the recreational fishing season (December‐May). No differences were observed in the lower jaw‐fork length (LJFL)‐weight (W) relationship between sexes or years but average weight of females (106.2 ±1.1 kg) was significantly greater than males (90.2 ±1.2 kg) from 1985 to 1994 (F684 = 88.37, P < 0.001). Negative allometric growth (W = 2E ‐08 LJFL2.88) was recorded for all striped marlin. Individual growth was modelled by fitting backcalculated LJFL to eight age classes derived from dorsal spine measurements (n = 94) using the von Bertalanffy growth equation (r2 = 0.96). The parameters estimated in the von Bertalanffy growth equation were asymptotic length (L ) = 3010 mm, annual growth rate (K) = 0.22, age (yr) at hypothetical length 0 (t0) = ‐0.04.  相似文献   

8.
Growth of the bluenose, Hyperoglyphe antarctica (Carmichael, 1818) from the lower east coast, North Island, was determined by counting growth check rings in otoliths. One growth check ring appeared to be laid down each year, so this technique is probably valid for aging bluenose. Female fish had a significantly higher growth rate than males. Comparisons of samples from three sites indicated no significant regional differences in growth. The von Bertalanffy parameters L8,K, and t0 fitted to back‐calculated fish lengths were, respectively, 81.1 cm, 0.308, ‐0.627 for males, and 86.1 cm, 0.308, ‐0.384 for females.  相似文献   

9.
A combination of a three-dimensional hydrodynamic model and in-situ measurements provides the structures of barotropic tides, tidal circulation and their relationship with turbulent mixing in the Java Sea, which allow us to understand the impact of the tides on material distribution. The model retains high horizontal and vertical resolutions and is forced by the boundary conditions taken from a global model. The measurements are composed of the sea level at coastal stations and currents at moorings embedded in Seawatch buoys, in addition to hydrographic data. The simulated tidal elevations are in good agreement with the data for the K1 and M2 constituents. The K1 tide clearly shows the lowest mode resonance in the Java Sea with intensification around the nodal point in the central region. The M2 tide is secondary and propagates westward from the eastern open boundary, along with a counterclockwise amphidromic point in the western part. The K1 tide produces a major component of tidal energy, which flows westward and dissipates through the node region near the Karimata Strait. Meanwhile, the M2 tide dissipates in the entire Java Sea. However, the residual currents are mainly induced by the M2 tide, which flows westward following the M2 tidal wave propagation. The tidal mixing is mainly caused by K1 tide which peaks at the central region and is consistent with the uniform temperature and salinity along the vertical dimension. This mixing is expected to play an important role in the vertical exchange of nutrients and control of biological productivity.  相似文献   

10.
Serpulid patch reefs of Galeolaria hystrix Mörch, 1863 were found in water depths of 9–16 m in Big Glory Bay, Paterson Inlet, Stewart Island, and here we report preliminary studies of these important habitat‐formers. This is the first observation of this species in subtidal patch reefs; 114 reefs were noted in a survey of 28 000 m2. Most reefs were 1–5 m in diameter, and up to 1.5 m high. Up to 65% of the serpulid tubes were occupied by living G. hystrix during a mid‐winter diving survey; 64% of reefs observed were whole, whereas 36% were broken or dead. Radiometric dating of a basal specimen of reef carbonate showed it to be less than 50 years old. Production of high‐Mg calcite, ranging from 9 to 11 wt% MgCO3, by G. hystrix may be as much as 11 kg CaCO3 m‐2y‐1, but was not reflected in surrounding sediments, which were dominantly terrigenous muds. A rich reef fauna, both sessile and motile, was associated with the reefs. Further study of these unusual temperate reefs is strongly recommended.  相似文献   

11.
Laboratory experiments were carried out to investigate the effect of sustained light and temperature on the uptake of PO4 3 ‐P, NH/‐N, and NO3 ‐‐N and on the biomass of the phytoplankton of Lake Rotongaio. Two sets of experiments compared differences between the seasonally contrasting dominant phytoplankton species, which consist of a filamentous nitrogen‐fixing cyanophyte in summer and diatoms in winter. The extent to which nutrients became exhausted, cell N/P ratios changed, and nitrogen‐fixation was enhanced, depended on the amount of light supplied and strongly indicated that light is the limiting factor for phytoplankton growth under normal lake conditions. Re‐illumination after extended periods of darkness suggested that sedimentation below the euphotic zone could be tolerated by the phytoplankton, and that growth could be quickly reestablished upon re‐entry to better light conditions. Temperature could have some effect on metabolic rate but is probably of minor importance compared to light availability for the species selection and overall nutrient dynamics of the lake.  相似文献   

12.
南海东沙岛西南大陆坡内潮特征   总被引：2，自引：0，他引：2  
2008年4月-10月,在南海东沙岛西南大陆坡底部布放了1套全剖面锚系,同时沿大陆坡底部布放了3套近底锚系,应用谱分析和调和分析方法分析温度和海流连续观测资料,进而研究该海域的内潮特征.结果表明,东沙岛西南大陆坡存在强内潮现象,大陆坡底部温度变化受到内潮波的影响,上层海洋存在强日潮周期的内潮波振动;正压潮和斜压潮均以O...  相似文献   

13.
As with other benthic fish which bury themselves in sand, in Genyagnus monopterygius it is the branchiostegal apparatus which makes the major contribution to ventilation of the gills. The prolonged abduction of the branchiostegal membranes draws water in through the mouth, and exhaled water moves away from the fish through mucus‐lined channels in the sand. The steady and continuous flow of water during ventilation may avoid detection of the stargazer by prey or predators. Associated with its sluggish habits and the low gill surface area available for gas exchange, Genyagnus has a low rate of oxygen consumption (15.8 ml kg‐1 h‐1 for a 100 g fish at 17°C). At partial pressures of oxygen (PO2) below 6 kPa (45 mm Hg) oxygen consumption is reduced, but the fish does not emerge from the sand until the PO2 falls below 2 kPa. There is evidence that the fish can sustain an oxygen debt. Respiration in the stargazer is discussed in relation to the fish's ability to withstand temporary hypoxia when it is stranded above the water level in the intertidal zone.  相似文献   

14.
王逸涵  王韫玮  于谦  蔡辉  高抒 《海洋科学》2019,43(10):66-74
南黄海西侧的江苏海岸近岸区域,素以地形复杂、潮流强劲、悬沙输运剧烈著称,但是较长期的同步潮位和潮流观测数据仍然缺乏,尤其是在近岸(20 km)浅水(20 m)区域。2014年1月在大丰港附近开展了连续潮位和潮流观测,获得的数据揭示了一系列特征。此地潮汐潮流为正规半日潮,浅水分潮显著。平均潮差为3.05 m,最显著的两个分潮为M2和S2分潮,振幅分别为1.45 m和0.52 m。潮流最显著的半日分潮M2分潮和最显著的浅水分潮M4分潮在沿岸方向上振幅分别为0.84m/s和0.12m/s,在跨岸方向上振幅分别为0.24 m/s和0.01 m/s,沿岸方向占绝对优势。潮波的沿岸传播介于前进波和驻波之间,驻波的特征稍强。M2分潮潮流椭圆最大流(长轴)方向为南偏东7.4°。存在冬季沿岸向北的余流,垂向平均值的大小为2.2 cm/s。以上潮汐潮流特征为该区域海洋物质输运研究提供了基础资料。  相似文献   

15.
南麂岛附近海域潮汐和潮流的特征   总被引：4，自引：2，他引：2  
以2008年冬季在浙江近海南麂岛附近投放的4个底锚系观测的水位和流速资料为依据,分析了潮汐和潮流特征。水位谱分析结果显示半日分潮最显著,全日分潮其次;近岸的浅水分潮比离岸大。水位调和分析结果表明:潮汐类型均为正规半日潮,近岸处的平均潮差大于3m,最大可能潮差大于6m,潮汐呈现出显著的低潮日不等和回归潮特征。流速谱分析结果显示半日分潮流最强,全日分潮流其次,且比半日分潮流小得多;近岸浅水分潮流比远离岸显著。流速调和分析结果表明:潮流类型均为正规半日潮流,靠近岸的两个站浅水分潮流较显著;最显著的半日分潮流是M2分潮流,其最大流速介于0.32～0.48m/s之间,全日分潮流均很弱,最大流速小于0.06m/s。M2分潮流均为逆时针旋转,椭圆率越靠近海底越大;最大分潮流流速分布为中上层最大、表层略小、底层最小;最大分潮流流速方向的垂向变化很小,底层比表层略为偏左;最大分潮流流速到达时间随深度的加深而提前,底层比中上层约提前30min。潮流椭圆的垂向分布显示这里的半日分潮流以正压潮流为主;日分潮流则表现出很强的斜压性。  相似文献   

16.
Within the framework of a project comprising part of the Spanish Space Program related to the JASON-1 CNES (Centre National d'Etudes Spatiales)/NASA (National Aeronautics and Space Administration) mission, a campaign was conducted from June 9–17, 2003, on the Absolute Calibration Site of the island of Ibiza. The objective was to determine the local marine geoid slope under the ascending (187) and descending (248) Jason-1 ground tracks, in order to allow a better extrapolation of the open-ocean altimetric data with on-shore tide gauge locations, and thereby improve the overall precision of the calibration process. For this we have used a catamaran with two GPS antennas onboard, following the Corsica/Senetosa design (Bonnefond et al. 2003a Bonnefond, P., Exertier, P., Laurain, O., Menard, Y., Orsoni, A., Jeansou, E., Haines, B., Kubitschek, D. and Born, G. 2003a. Leveling Sea Surface using a GPS catamaran. Marine Geodesy, 26(3–4): 319–334. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). Five GPS reference stations were deployed in order to reduce the distance between the areas covered by the catamaran and the fixed GPS receiver used in the kinematic process. The geodetic activities (e.g., GPS, leveling) have enabled the building of a very accurate (few mm) network in a reference frame compatible with the satellite altimetry missions (ITRF 2000). The GPS kinematic data were processed using two different software programmes, allowing checking of the consistency of the solutions. If the standard deviation of the differences (3.3 cm) is close to the kinematic process precision, they exhibit some large values (up to 14 cm). These large discrepancies have been reduced using a weighting based on the crossover differences. Inasmuch as the distances between the tide gauges and the areas covered by the GPS catamaran were becoming large, we have used the MOG2D ocean model (Carrère and Lyard 2003 Carrère, L. and Lyard, F. 2003. Modelling the barotropic response of the global ocean to atmospheric wind and pressure forcing—comparisons with observations. Geophys. Res. Letters, 30(6) [Google Scholar]) to correct the sea surface from tides. In the farthest areas, the crossover differences show an improvement by a factor of two. Finally, we also present preliminary results on Jason-1 altimeter calibration using the derived marine geoid. From this analysis, the altimeter bias is estimated to be 120 ± 5 mm. The quality of this first result validates the whole GPS-based marine geoid processing, for which the accuracy is estimated to be better than 3 cm rms at crossovers.  相似文献   

17.
Average values of inherent optical properties for the 400–700 nm waveband were estimated from quantum irradiance measurements on 27 New Zealand lakes of diverse optical character, using published nomograms. Secchi disc depths, turbidity, algal pigment, non‐volatile suspended solids, and absorption by membrane‐filtered samples at 440 nm (g 440 ) were also measured. Turbidity (NTU) correlated closely with the scattering coefficient (m‐1) and these quantities were almost numerically equal, as found in other studies. The data were found to conform to an expression in the oceanographic literature relating Secchi disc depth to the beam attenuation and diffuse attenuation coefficients. Specific beam attenuation, scattering, and absorption coefficients were estimated from the coefficients of linear multiple regressions of the measured total coefficients on the variables: total pigment (chlorophyll a + phaeopigment), non‐volatile suspended solids, and g 440. The estimated values were in reasonable agreement with similar specific coefficients reported in the oceanographic literature. The coefficients provide a basis for predicting clarity in new impoundments or for predicting the effects of loading changes (e.g., of nutrients) on the clarity of existing lakes. The coefficients can be used for classifying lake waters into different optical types.  相似文献   

18.
Using the three-dimensional nonlinear finite-element thermohydrodynamic model QUODDY-4, we obtain two solutions giving an idea of the role of the nonlinear interaction of tidal harmonics in the formation of their spatial structure. The first solution is induced by the total tide (M 2 + S 2 + K 1 + O 1) at the open boundary and by the total static tide inside the area under consideration; then, the solution obtained is subject to harmonic analysis. The second solution is obtained by specifying such tidal sea level elevations at the open boundary that meet individual tidal harmonics. These two solutions are compared. It is shown that the differences between the solutions for the S 2, K 1, and O 1 waves can be significant, especially near the open boundary between the White and Barents seas. This conclusion remains valid also for the maximum velocities (major semiaxes of the ellipses) of the barotropic (depth-average) tidal current as well as for the average (over the tidal cycle) densities of the total tidal energy and components of the tidal-energy budget. The emergence of this feature indicates that there are resonance modes with frequencies that differ from those of the S 2, K 1, and O 1 harmonics to a lesser extent than the M 2 harmonic frequency. The same conclusion can be made by comparing the values of the amplification factor, which is defined as the ratio between the actual and static tides, for the system of the Barents and White seas as a whole and for Mezen Bay in the White Sea and Czech Bay in the Barents Sea, taken separately.  相似文献   

19.
The Sofala Bank, a wide shelf located along the central coast of Mozambique, hosts tides with high amplitudes. The Regional Ocean Modelling System (ROMS) was used to analyse the tidal currents on the bank and to investigate their effects on the stratification and generation of tidal fronts. During spring tides, barotropic tidal currents with maximum values ranging from 40 cm s–1 to 70 cm s–1 are found on the central bank. The major axis of the tidal ellipses for M2 and S2 follow a cross-shelf direction with mainly anticlockwise rotation. Similar to observations, three distinct regimes occur: (i) a warm well-mixed region on the inner shelf where the depths are <30 m; (ii) a wellmixed colder region above the shelf edge; and (iii) a stratified region offshore. The model shows that the tides lead to cooling where two criteria are satisfied: the Simpson and Hunter parameter log10(h/U3) <3.2 and the depth h >30 m. The shelf edge of the bank is important for internal tide generation. Two frontal structures result, one offshore between cooler mixed waters and warmer stratified waters and the other in shallow inshore waters, between cooler mixed waters and solar heated mixed waters.  相似文献   

20.
Availability of soil and sediment phosphorus to a planktonic alga   总被引：1，自引：1，他引：0  
Chlorophyll production by Chlorella vulgaris Beij. var. vulgaris was used to estimate alga‐available phosphorus in clays, soils, and lake sediments suspended in water at concentrations appropriate to lake inflows during floods (100–500 g/m3). Chlorella apparently used 24–81% of 0.5M H2SO4 extractable phosphorus in clays from topsoils, about 25% from lake sediments, and 0.3–1.0% from, subsoils low in phosphorus and with high phosphorus retention.

The presence of suspended soil material did not reduce the availability to Chlorella of inorganic phosphorus added to the cultures. Increasing the Chlorella population by adding inorganic phosphorus resulted in an apparent increase in availability of phosphorus from the soil, possibly as a result of enzymic mineralisation of organic soil phosphorus. The amount of available phosphorus in lake sediments was not a reliable guide to the trophic condition, of the lake.

Suspended material from sediments, soils, and especially clay eroded from fertilised topsoils may provide phosphorus for algal growth in lakes. If allophanic clays are applied to lakes to sorb phosphorus and hence control eutrophication, the particles must settle out before planktonic algae in the photic zone can use the adsorbed phosphorus.  相似文献   

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