Studies of the Hydrobiology of a Tropical Lake in North-western Queensland. I. Seasonal Changes in Chemical Characteristics

1979 ◽  
Vol 30 (5) ◽  
pp. 579 ◽  
Author(s):  
TP Farrell ◽  
CM Finlayson ◽  
DJ Griffiths
Keyword(s):  
Ionic Composition ◽  
Sampling Period ◽  
Climatic Conditions ◽  
Chemical Characteristics ◽  
Artificial Lake ◽  
Heavy Metal Concentrations ◽  
Run Off ◽  
Major Nutrients ◽  
Lake Waters ◽  
North Western

The chemical characteristics of the water of Lake Moondarra, an artificial lake in tropical north-western Queensland, are described. Changes in ionic composition, and in the concentrations of major nutrients and heavy metals, were monitored over a 12 month sampling period. Seasonal variations within the lake were strongly influenced by climatic conditions, principally rainfall which affects run-off and dilution by way of the intermittently flowing river and creeks. The results show that, in spite of the considerable input of nutrients, their concentration in the lake waters remains consistently low. The heavy metal concentrations in the lake water are also well below the limits regarded as acceptable for drinking water.

scholarly journals A new Middle Pleistocene interglacial sequence from Måløv, Sjælland, Denmark

1969 ◽  
Vol 23 ◽  
pp. 29-32
Author(s):  
Ole Bennike ◽  
Esben Lindgård ◽  
Henrik Jønsson Granat ◽  
Richard C. Preece ◽  
Finn Viehberg
Keyword(s):  
Deep Sea ◽  
Western Europe ◽  
Sediment Cores ◽  
Climatic Conditions ◽  
Middle Pleistocene ◽  
Arctic Species ◽  
Relative Age ◽  
Quaternary Sequences ◽  
Animal Remains ◽  
North Western

Interglacial deposits in Denmark have traditionally been referred to the Cromerian complex (Hareskovian), Holsteinian or Eemian stages. However, based on studies of sediment cores from the deep sea many more than three Quaternary interglacials have been documented, and in other parts of north-western Europe it is becoming increasingly clear that the on-shore Quaternary sequences are much more complex than previously believed. Interglacial deposits are characterised by plant and animal remains indicating longer periods with climatic conditions similar to or warmer than today, whereas interstadial deposits were formed during shorter time spans and usually contain remains of relatively coldadapted, arctic or sub-arctic species. Interglacial and interstadial deposits can be dated more or less precisely, and thus provide information about the relative age of glacial deposits.

scholarly journals Brief communication: Glacier run-off estimation using altimetry derived basin volume change: case study at Humboldt Glacier, Northwest Greenland

2020 ◽  
Author(s):  
Laurence Gray
Keyword(s):  
Volume Change ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Run Off ◽  
Height Change ◽  
North Western

Abstract. CryoSat can provide temporal height change around the Greenland Ice Sheet including that close to the terminus of many glaciers. Height change from the northern outlet of the Humboldt Glacier in north-western Greenland is combined with ice flux into and out of sections of the glacier basin to derive the water run-off each year from 2011 to 2019. The cumulative nine-year run-off for this part of the Humboldt basin is 9.6 ± 2.9 km3 and is predominantly sub-glacial at the terminus with large run-offs occurring in 2012, 2015 and 2019, and much smaller ones in 2013, 2016, 2017 and 2018.

Using Geospatial Techniques to Analyze Landscape Factors Controlling Ionic Composition of Arctic Lakes, Toolik Lake Region, Alaska

2012 ◽  
Vol 3 (3) ◽  
pp. 37-57 ◽  
Author(s):  
Prasad Pathak ◽  
Stephen Whalen
Keyword(s):  
Ionic Composition ◽  
Arctic Lakes ◽  
The Arctic ◽  
Geospatial Techniques ◽  
Arctic Alaska ◽  
Data Regression ◽  
Concentration Of Ions ◽  
Major Nutrients ◽  
Patch Density ◽  
Shape Complexity

The impacts of climate change on landscapes in arctic Alaska are evident in terms of permafrost melting, frequent thermokarst activity, and the occurrence of more broadleaf vegetation. These changes may alter natural biogeochemical cycles of ions along with major nutrients and affect ionic compositions of lakes, as they are connected with the landscapes. However, the nature of the connectivity between lakes and landscapes in this region is not yet explored. The authors propose that geospatial analysis of landscape properties along with observed lake ion concentrations will enable an understanding of the currently existing landscape controls over ion inputs into the lakes. For the watersheds of 41 lakes in the Arctic Foothills region of Alaska, spatial properties of natural vegetation communities expressed in terms of percentage, shape complexity, and patch density metrics were derived using satellite data. Regression analyses were performed for concentration of ions as well as conductivity in lake water where the spatial metrics along with lake physical properties, lake order, and glacial till age categories were used as predicting variables in the regression. Landscape metrics for major land covers i.e., Percentage of Moist Acidic Tundra (MAT) and Moist Non-acidic Tundra (MNT) were the major predicting variables for concentration of several ions.

FLAX STUDIES: IV. THE PHYSICAL AND CHEMICAL CHARACTERISTICS OF FLAXSEED AT PROGRESSIVE STAGES OF MATURITY

1939 ◽  
Vol 17c (6) ◽  
pp. 181-194 ◽  
Author(s):  
F. H. Lehberg ◽  
W. G. McGregor ◽  
W. F. Geddes
Keyword(s):  
Oil Content ◽  
Kernel Weight ◽  
Climatic Conditions ◽  
Chemical Characteristics ◽  
Physical And Chemical Characteristics ◽  
Flowering Rate ◽  
Iodine Values ◽  
Physical And Chemical

Flaxseed from plots seeded at Ottawa and Saskatoon over a period of several weeks and harvested at maturity showed no difference in oil content with dates of seeding, but the iodine values tended to increase with late seeding. Experiments conducted with Bison and Redwing grown in 1936 at Brandon, Saskatoon Edmonton, and Fallis, and with Redwing in 1937 at Brandon, Edmonton, and Fallis, in which the seed was harvested at successive stages of maturity, showed that moisture decreased and dry kernel weight and oil content increased with progressive maturity up to approximately thirty days after flowering. Rate of oil deposition was in some cases extremely rapid, from 80% to 90% of the maximum oil found being deposited by the fifteenth to eighteenth day. Oil content and dry kernel weight reach a maximum several days before visual maturity. Unsaturation proceeds somewhat more slowly and reaches a higher value under climatic conditions favouring slow maturity.

scholarly journals Actividad reproductiva y dieta de Hemidactylus frenatus (Sauria: Gekkonidae) en el norte de Colombia

2017 ◽  
Vol 57 (36) ◽  
pp. 459
Author(s):  
Jorge A. Díaz-Pérez ◽  
Alcides C. Sampedro-Marín ◽  
Martha P. Ramírez-Pinilla
Keyword(s):  
Diet Composition ◽  
Sampling Period ◽  
Reproductive Activity ◽  
Climatic Conditions ◽  
Relative Importance ◽  
Adult Males ◽  
Adult Females ◽  
Ecological Aspects ◽  
Environmental Availability ◽  
Hemidactylus Frenatus

Despite its success as an invasive species, little is known about the ecological aspects of the gekkonid lizard Hemidactylus frenatus in Colombia. In the present study the size at maturity, sexual dimorphism, reproductive activity, and diet composition of a population of this species in an urban locality of Northern Colombia were determined. We conducted eleven samplings from September 2011 to August 2012 in buildings of the municipality of Sincelejo. A total of 264 specimens H. frenatus were captured, 112 were adult females, 133 adult males and 19 juveniles. Males reach sexual maturity at a smaller size (snout-vent length) than females (males: 35.7 mm; females: 42.7 mm), also they are larger and have proportionally larger heads and mouths than females. Males were reproductive throughout the year; although testicular volume varied significantly between samples, this variation was not associated with body size and precipitation in the study area. Reproductive adult females were found during all the sampling period. Females have an invariable clutch size of two eggs and we found no differences in the diameter and weight of eggs in each oviduct. The diet of H. frenatus is varied, with Diptera, Hemiptera and Formicidae being the prey types with the greatest relative importance values. Individuals of both sexes consume a similar volume and number of prey. Thus, the studied population of H. frenatus has continuous reproductive activity and a generalist-opportunistic feeding behavior. The climatic conditions of the study area, environmental availability of prey and intrinsic features of this species appear to be responsible for their abundance and colonizing success in this and other localities.

scholarly journals Variability of water repellency in sandy forest soils under broadleaves and conifers in north-western Jutland/Denmark

2008 ◽  
Vol 3 (Special Issue No. 1) ◽  
pp. S155-S164 ◽  
Author(s):  
N.A Wahl
Keyword(s):  
Soil Water ◽  
Preferential Flow ◽  
Water Drop ◽  
Water Repellency ◽  
Climatic Conditions ◽  
Tree Age ◽  
Critical Surface ◽  
Soil Water Repellency ◽  
Wide Range ◽  
North Western

Soil water repellency has important consequences for ecological and hydrological properties of soils and usually retards infiltration capacity and induces preferential flow. This phenomenon has been known to occur on a wide range of sites under a variety of climatic conditions. The objective of this study was to investigate and characterize soil water repellency on forest sites with identical substrate and climatic conditions, differing in tree age and species. In the Vester Torup Klitplantage, an area comprising a conifer dominated forest plantation stocking on sandy deposits in a coastal setting near the Jammer Bay in north-western Jutland/Denmark, four different forest plots were investigated for water repellency effects four times in 2005. To measure soil water repellency, the water drop penetration time test and the critical surface tension test were carried out. Both tests revealed a seasonal variability in water repellency, exhibiting the highest water repellency for the upper 10 cm of the soil during the summer months, whereas the variability between the different plots seems to be less significant. There was no coherence between humus forms, thickness of litter layer and water repellency.

scholarly journals IX.—On the Glacial Succession in Europe

1895 ◽  
Vol 37 (1) ◽  
pp. 127-149
Author(s):  
James Geikie
Keyword(s):  
North Sea ◽  
Western Europe ◽  
Climatic Conditions ◽  
Marine Origin ◽  
The North ◽  
Pleistocene Period ◽  
The North Sea ◽  
North Western

For many years geologists have recognised the occurrence of at least two boulder-clays in the British Islands and the corresponding latitudes of the Continent. It is no longer doubted that these are the products of two separate and distinct glacial epochs. This has been demonstrated by the appearance of intercalated deposits of terrestrial, freshwater, or, as the case may be, marine origin. Such interglacial accumulations have been met with again and again in Britain, and they have likewise been detected at many places on the Continent, between the border of the North Sea and the heart of Russia. Their organic contents indicate in some cases cold climatic conditions; in others, they imply a climate not less temperate or even more genial than that which now obtains in the regions where they occur. Nor are such interglacial beds confined to northern and north-western Europe. In the Alpine Lands of the central and southern regions of our Continent they are equally well developed. Impressed by the growing strength of the evidence, it is no wonder that geologists, after a season of doubt, should at last agree in the conclusion that the glacial conditions of the Pleistocene period were interrupted by at least one protracted interglacial epoch. Not a few observers go further, and maintain that the evidence indicates more than this. They hold that three or even more glacial epochs supervened in Pleistocene times. This is the conclusion I reached many years ago, and I now purpose reviewing the evidence which has accumulated since then, in order to show how far it goes to support that conclusion.

scholarly journals The hydro-meteorological chain in Piemonte region, North Western Italy - analysis of the HYDROPTIMET test cases

2005 ◽  
Vol 5 (6) ◽  
pp. 845-852 ◽  
Author(s):  
D. Rabuffetti ◽  
M. Milelli
Keyword(s):  
Numerical Models ◽  
Precipitation Forecast ◽  
Test Cases ◽  
Warning Systems ◽  
Alert System ◽  
Run Off ◽  
Quantitative Precipitation Forecast ◽  
Prediction And Prevention ◽  
Meteorological Models ◽  
North Western

Abstract. The HYDROPTIMET Project, Interreg IIIB EU program, is developed in the framework of the prediction and prevention of natural hazards related to severe hydro-meteorological events and aims to the optimisation of Hydro-Meteorological warning systems by the experimentation of new tools (such as numerical models) to be used operationally for risk assessment. The objects of the research are the mesoscale weather phenomena and the response of watersheds with size ranging from 102 to 103 km2. Non-hydrostatic meteorological models are used to catch such phenomena at a regional level focusing on the Quantitative Precipitation Forecast (QPF). Furthermore hydrological Quantitative Discharge Forecast (QDF) are performed by the simulation of run-off generation and flood propagation in the main rivers of the territory. In this way observed data and QPF are used, in a real-time configuration, for one-way forcing of the hydrological model that works operationally connected to the Piemonte Region Alert System. The main hydro-meteorological events that affected Piemonte Region in the last years are analysed, these are the HYDROPTIMET selected test cases of 14–18 November 2002 and 23–26 November 2002. The results obtained in terms of QPF and QDF offer a basis to evaluate the sensitivity of the whole hydro-meteorological chain to the uncertainties in the numerical simulations. Different configurations of non-hydrostatic meteorological models are also evaluated.

scholarly journals Simulation of Run-Off from the Greenland Ice Sheet for Planning Hydro-Electric Power, Ilulissat/Jakobshavn, West Greenland

1989 ◽  
Vol 13 ◽  
pp. 12-15 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Henrik Højmark Thomsen
Keyword(s):  
Electric Power ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Climatic Conditions ◽  
Electric Power Station ◽  
Hydroelectric Power ◽  
Drainage Pattern ◽  
West Greenland ◽  
Run Off ◽  
Hydraulic Conditions

Simulations of run-off from the Greenland ice sheet were made as part of a feasibility study for provision of hydroelectric power for Ilulissat/Jakobshavn, West Greenland. The aims were to see if the available short series of run-off measurements are typical of those under present climatic conditions, and to assess possible changes in run-off likely to be caused by gross changes in drainage pattern on the ice sheet. Specific run-off was calculated from climatological data, whilst run-off volumes were calculated by integrating specific run-off over the area of the ice sheet. There have been substantial year-to-year variations in run-off, but the 6 year measurement period is reasonably representative of present climatic conditions. Run-off could be reduced by 21% as a result of changes in hydraulic conditions on the ice sheet without this having a significant effect on the economy of the planned hydro-electric power station.

scholarly journals Surface and Groundwater Hydrochemistry of the Menengai Caldera Geothermal Field and Surrounding Nakuru County, Kenya

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3131 ◽  
Author(s):  
Nelly Montcoudiol ◽  
Neil M. Burnside ◽  
Domokos Györe ◽  
Nicholas Mariita ◽  
Thecla Mutia ◽  
...  
Keyword(s):  
Ionic Composition ◽  
Sampling Period ◽  
Geothermal Field ◽  
Wet Season ◽  
Lake Nakuru ◽  
Rock Interaction ◽  
Geothermal Wells ◽  
Groundwater Hydrochemistry ◽  
Hydrological System ◽  
Oxygen Isotopic

In order to assess the sustainability and impact of production from geothermal reservoirs on hydrological systems, a thorough understanding of local and regional hydrogeological systematics is a prerequisite. The Menengai Caldera in the Kenya Great Rift Valley is one of the largest explored geothermal fields in the country. This paper presents a hydrochemical investigation of the Menengai Caldera geothermal field and the ground and surface waters of the surrounding Nakuru County. Our results demonstrated a similar, sodium-alkaline dominated, ionic composition across all water types. Geothermal wells return the highest cation/anion concentrations and largely demonstrate a meteoric source from their δ18O and δ2H signature. Wells MW-09 (central part of the caldera), MW-18 (eastern part) and MW-20 (central part) showed a more evaporitic signature, closely matching with our own calculated Lake Evaporation Line, suggesting an increased mixing influence of Lake Nakuru waters. MW-09 also showed evidence of high-temperature oxygen isotopic exchange and significant water-rock interaction. Lake samples largely demonstrated seasonal shifts in ionic and isotopic values. Lake Nakuru ionic composition and isotopic values increased throughout the 12-month wet–dry–wet season sampling period. This correlated with a decrease in area which suggests a lessening of water inflow and facilitates increased evaporation. Groundwaters demonstrated clear evidence of mixing between meteoric, irrigation and lake waters. These observations enhanced the understanding of the hydrological system surrounding the Menengai Caldera and, when combined with future studies, will provide a powerful tool to assess the sustainability and impact of soon-to-be completed geothermal power production operations.

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