Sediment-Pore Water Chemistry of Taupo Volcanic Zone Lakes and the Effect Trophic State has on Exchange with the Water Column
type: CreativeWork
description: The Taupo Volcanic Zone (TVZ) is in the Waikato and the Bay of Plenty regions of North Island of New Zealand and contains many volcanic lakes of diverse history, physiography, and limnology. The lakes vary in size (0.2 to 620 km2), mixing regime (monomictic and polymictic), and trophic status (oligotrophic to supertrophic). The purpose of this study is to develop an understanding of the sediment-pore water interactions over a range of trophic conditions and how the biogeochemical cycles influence the lake ecosystem and the implications that this has for management of the TVZ lakes. The monthly changes in composition of lake water, pore water, sediments and stable isotopes of dinitrogen gas were monitored in five monomictic TVZ lakes (Taupo, Tarawera, Okataina, Rotoiti and Ngapouri) of widely varying trophic state, in order to evaluate the interaction between sediments and lake water. In particular, 15N enrichment in the benthic nepheloid layer (BNL), sediment-pore water geochemistry, the lead record in the sediment and silicon as a potential limiting nutrient for diatom growth were studied. In addition to the monthly analysis, discrete studies were extended to 9 other lakes of the Rotorua District (Te Arawa Lakes) to reinforce the findings of the monthly study. The applicability of the natural abundance of nitrogen gas isotope ratios was used to indicate the spatial distribution of nitrogen transformations in the water column and sediment pore waters of Lake Ngapouri. A method is introduced to extract gas from water samples to measure δ15N [N2] Samples were collected from the epilimnion, hypolimnion, benthic nepheloid layer and at 5 cm intervals from the sediment pore waters at monthly intervals for one year. Values of δ15N [N2] ranged from -1 to 0.28 ‰ in the epilimnion, -1.5 to 1.25 ‰ in the hypolimnion, -1.8 to 12.2 ‰ in the benthic nepheloid layer and -0.7 to 3.5‰ in sediment pore waters. Values of δ15N [N2] showed a strong seasonal pattern that was related to t…
abstract: The Taupo Volcanic Zone (TVZ) is in the Waikato and the Bay of Plenty regions of North Island of New Zealand and contains many volcanic lakes of diverse history, physiography, and limnology. The lakes vary in size (0.2 to 620 km2), mixing regime (monomictic and polymictic), and trophic status (oligotrophic to supertrophic). The purpose of this study is to develop an understanding of the sediment-pore water interactions over a range of trophic conditions and how the biogeochemical cycles influence the lake ecosystem and the implications that this has for management of the TVZ lakes. The monthly changes in composition of lake water, pore water, sediments and stable isotopes of dinitrogen gas were monitored in five monomictic TVZ lakes (Taupo, Tarawera, Okataina, Rotoiti and Ngapouri) of widely varying trophic state, in order to evaluate the interaction between sediments and lake water. In particular, 15N enrichment in the benthic nepheloid layer (BNL), sediment-pore water geochemistry, the lead record in the sediment and silicon as a potential limiting nutrient for diatom growth were studied. In addition to the monthly analysis, discrete studies were extended to 9 other lakes of the Rotorua District (Te Arawa Lakes) to reinforce the findings of the monthly study. The applicability of the natural abundance of nitrogen gas isotope ratios was used to indicate the spatial distribution of nitrogen transformations in the water column and sediment pore waters of Lake Ngapouri. A method is introduced to extract gas from water samples to measure δ15N [N2] Samples were collected from the epilimnion, hypolimnion, benthic nepheloid layer and at 5 cm intervals from the sediment pore waters at monthly intervals for one year. Values of δ15N [N2] ranged from -1 to 0.28 ‰ in the epilimnion, -1.5 to 1.25 ‰ in the hypolimnion, -1.8 to 12.2 ‰ in the benthic nepheloid layer and -0.7 to 3.5‰ in sediment pore waters. Values of δ15N [N2] showed a strong seasonal pattern that was related to t…
author: Pearson, Lisa Kyle
license: https://researchcommons.waikato.ac.nz/bitstreams/ddd8b572-e2c6-46f8-83c6-84113ca16062/download
date published: 2012
date modified: 2026-07-24T05:57:33Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Waikato