Application of natural and artificial fallout radionuclides to determining sedimentation rates in New Zealand lakes

Whitehead, N. E.; Ditchburn, R.G.; McCabe, W.J.; Mason, W.J.; Irwin, J.; Pickrill, R. A.; Fish, G. R.

doi:10.1080/00288330.1998.9516838

Cited by 5 publications

(5 citation statements)

References 28 publications

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“…The sedimentary rate of c. 22 mm/yr based on the occurrence of Pinus pollen throughout the studied section is more than three times the speed indicated by the 137 Cs rate of c. 6.7 mm/yr since 1953 (Graham et al 2005) or 210 Pb rate of 4.7 mm/yr (Whitehead et al 1998). It is possible that this inconsistency is caused by a faster sedimentary rate before 1953 when occasional slumps occurred, a hydro-electric dam was constructed, and the lake level controlled (Graham et al 2005).…”

Section: Mechanism and Timing Of Laminae Formationmentioning

confidence: 78%

Reconnaissance sediment and microfossil analyses of a laminated short piston core from Lake Tekapo, South Island, New Zealand

Mildenhall

Cochran

Cook

2006

New Zealand Journal of Geology and Geophysics

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A 2.2 m piston core from the main basin of Lake Tekapo comprises millimetre-centimetre-scale alternations of light and dark laminae. Two much thicker layers occur near the base of the core and are interpreted as major slump deposits. Light laminae are predominantly fine silts with low microfossil concentrations. Dark laminae have higher clay, mica, and microfossil content and higher planktic/benthic diatom ratios. These findings are consistent with light laminae being deposited during times of high river flow and high sediment input, the thickness and number forming a proxy for paleoclimate (rainfall, water inflow, and erosion rates), and the dark laminae being deposited by settling out of the water column during periods of low inflow. The distribution of pollen from plants introduced to New Zealand by Europeans, and the inconsistency of dominant pollen types between samples, suggests that the entire sequence is only c. 100 yr old and that couplets of light and dark laminae form more frequently than annually. With appropriate processing, diatoms, spores, and pollen are present in great enough numbers in the dark laminae to be used for paleoclimate reconstruction. Diatoms are predominantly planktic lacustrine forms with some benthic forms sourced from the lake margins. Pollen and spores are derived from local grasslands, montane forest, fell fields, and tussock lands, and from West Coast lowland forest. Palynomorphs are carried over the central Southern Alps by prevailing northwesterly winds, and are deposited in the lake. The presence of fresh-looking Casuarina and possibly Banksia and Eucalyptus pollen shows that it is likely that some pollen came from Australia. It is believed that the presence and abundance of West Coast derived pollen, particularly Dacrydium cupressinum, and to a lesser extent Ascarina lucida, Nothofagus, and Podocarpus/Prumnopitys species, could be used as a proxy for the intensity and persistence of northwesterly winds.

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Section: Mechanism and Timing Of Laminae Formationmentioning

confidence: 78%

Reconnaissance sediment and microfossil analyses of a laminated short piston core from Lake Tekapo, South Island, New Zealand

Mildenhall

Cochran

Cook

2006

New Zealand Journal of Geology and Geophysics

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“…The sedimentation rate was high compared to results shown from various studies. For instance, the sedimentation rate in the Lake Pukaki, New Zealand was 28 kg/m 2 /year and the Lake Tikitapu, New Zealand was 0.11 kg/m 2 /year (Whitehead et al 1998). Tanaka et al (1994) found that the sedimentation rate in the Lake Mashu, Japan ranging from 6.4 to 7.4 mg/cm 2 /year.…”

Section: Figure 7 Spatial Variations Of Sedimentation Ratementioning

confidence: 99%

“…Common techniques used in sedimentation rate studies are using sediment coring and radionuclide isotope such as 137 Cs (Nishri and Koren 1994;Fernex et al 2001;Whitehead et al 1998;Tanaka et al 1994). Other technique is to measure sedimentation rate by means of sediment traps, which has become a common practice in limnological research.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal variations of sedimentation rate in the Timah Tasoh Water Reservoir, Perlis, Malaysia

Rahaman¹,

Ismail²

2010

Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation

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Spatial and temporal variations of sedimentation rate in the Timah Tasoh Water Reservoir, Perlis, Malaysia. Human activities such as logging, land conservation, road construction and other disturbances in watersheds will increase erosion rate and thus the amount of sediment transported into the river that reaches lakes, reservoirs and sea. Accelerated sedimentation rate in the reservoir can signifi cantly reduce a reservoir's surface area, eliminating wetland area surrounding the reservoir and shallow the areas near the shore of the reservoir. A study of sedimentation rate in the Timah Tasoh water reservoir was carried out from May 2001 to April 2002 by means of sediment traps. The aim of this study is to determine the spatial and temporal pattern of sedimentation rates in the reservoir. The sediment traps were installed at fi ve different locations in the reservoir and replaced every month. Gross sedimentation rates measured in the sediment traps vary from about an average of 1.4 kg/m 2 /month or 16.3 kg/m 2 /yr in the deepest part of the reservoir to about 79.2 kg/m 2 /yr (monthly average of 6.6 kg/m 2 /month) and 47.1 kg/m 2 /yr (monthly average of 3.9 kg/m 2 /month) near the inlet of the Pelarit River and the Tasoh River respectively. The sedimentation rate near the Pelarit River and the Tasoh River infl ow is correlated with the water and suspended sediment discharge in the river, owing to its proximity to the rivers and the fl ooding effect, mainly during the wet season. The sedimentation rate decreases southward along the reservoir, as a result of increasing distance from the river mouth. The total suspended sediment load of the Upper Pelarit River and the Jarum River fl owing into the reservoir is 11.4 × 10 3 ton/year and 5.41 × 10 3 ton/ /year respectively.

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“…Using 137 Cs as a dating technique was pioneered in the 1970's (Whitehead et al, 1998) and since has been extensively used as a stratigraphic marker for determining geomorphic processes such as sediment erosion and deposition (Vanden et al, 2001). It is useful in this respect as the radio nuclide is essentially non exchangeable and has a limited mobility by chemical processes (Owens et al, 1995) and so leaves a distinct signature within the soil profile.…”

Section: Caesium 137 ( 137 Cs)mentioning

confidence: 99%

“…Concentrations of radio nuclides have varied over time; their peak deposition occurred in the mid 1960's, corresponding to the peak of atmospheric bomb testing (Whitehead et al, 1998). The nuclear fallout peak in New Zealand occurred in 1964, 2 -3 years after the northern hemisphere (Matthews, 1995), receiving only a tenth of the northern hemisphere fallout (Bishop et al, 1991).…”

Section: Caesium 137 ( 137 Cs)mentioning

confidence: 99%

The Geomorphology of Farewell Spit and Its Sensitivity to Sea-Level Rise

Tribe¹

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<p>Sand-dominated barriers are highly sensitive coastal systems which alter their morphology in response to rising sea level, undergoing extensive sediment reworking as wave activity reaches further inland. Farewell Spit, South Island, New Zealand, is a sand-dominated barrier spit which extends 25kms eastward from the mainland, enclosing the northwestern corner of the macro-tidal Golden Bay. During spring tide cycles low-lying areas of the Spit become completely inundated. The aim of this study is to establish the morphological stability of Farewell Spit and its potential response to the latest IPCC projected eustatic sea-level rise of 0.48m (A1B scenario) by the end of this century. GIS analysis of aerial photographs and the identification of 137Cs signatures within the dunes have shown a high degree of mobility in the Spit's features over the past 55 years. Vegetation increased by 75%, mainly due to the introduction of A arenaria, which has also led to the development of foredunes prograding up to 142m over the tidal flats. Barchan dunes on the Spit are also highly mobile migrating at up to 30m/y. The high amount of sediment movement along the spit is reflected in the sedimentology of the tidal flats, which show layers of aeolian transported fine, well-sorted sand several centimetres thick. The predominance of medium sand shows that reworking appears to have occurred on these flats due to storm events in Golden Bay, and like the dunes, 14C dating indicates they are very young features Projected sea-level rise was modelled to assess the vulnerability of low-lying areas of the Spit to tidal flooding. Deeper water levels in the two tidal channels which currently flood across the Spit are expected and there is a risk of additional channels opening, one being very near to the contact between the Spit and mainland. The mobility of the dune systems may however buffer some of these processes by providing natural defences against the sea. Barrier roll over does not appear to be an important process as it appears to be too wide to allow for washover. It is concluded that under current sea-level rise predictions Farewell Spit will not transgress landward but will be subject to exacerbated erosion.</p>

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Application of natural and artificial fallout radionuclides to determining sedimentation rates in New Zealand lakes

Cited by 5 publications

References 28 publications

Reconnaissance sediment and microfossil analyses of a laminated short piston core from Lake Tekapo, South Island, New Zealand

Reconnaissance sediment and microfossil analyses of a laminated short piston core from Lake Tekapo, South Island, New Zealand

Spatial and temporal variations of sedimentation rate in the Timah Tasoh Water Reservoir, Perlis, Malaysia

The Geomorphology of Farewell Spit and Its Sensitivity to Sea-Level Rise

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