title: Transition metal availability to speleothems controlled by organic binding ligands

authors: Hartland, Adam

subjects: Science & Technology

abstract: Speleothems are important archives of Quaternary palaeoclimate. However, climate proxies based on trace elements in speleothems are currently limited to the metals which exhibit simple partitioning (Mg²⁺, Sr²⁺, Ba²⁺). This study aims to expand understanding of the processes controlling the divalent first row transition metals (M²⁺) in these systems. Adsorptive cathodic stripping voltammetry was used to determine Cu speciation in speleothem dripwater, stream and pool samples from five limestone caves located in diverse climatic settings. Our results demonstrate that Cu binding and stabilisation by organic ligands (L) is a universal property of cave waters, which decreases the available Cu concentration ([Cu’]) by ~5 orders of magnitude relative to total Cu concentration ([CuT]). Furthermore, [Cu’] does not change meaningfully with increases in either [CuT] or [L], meaning that Cu²⁺ substitution in Ca²⁺ valence sites in precipitating CaCO₃ speleothems is likely to be inhibited by organic complexation. We suggest that the residence time of speleothem thin water films (1/drip rate), the dissociation rates of labile metal-organic complexes, and the stability of adsorbed (ternary) metal-organic complexes will determine M²⁺ incorporation in speleothems.

text: Transition metal availability to speleothems controlled by organic binding ligands Speleothems are important archives of Quaternary palaeoclimate. However, climate proxies based on trace elements in speleothems are currently limited to the metals which exhibit simple partitioning (Mg²⁺, Sr²⁺, Ba²⁺). This study aims to expand understanding of the processes controlling the divalent first row transition metals (M²⁺) in these systems. Adsorptive cathodic stripping voltammetry was used to determine Cu speciation in speleothem dripwater, stream and pool samples from five limestone caves located in diverse climatic settings. Our results demonstrate that Cu binding and stabilisation by organic ligands (L) is a universal property of cave waters, which decreases the available Cu concentration ([Cu’]) by ~5 orders of magnitude relative to total Cu concentration ([CuT]). Furthermore, [Cu’] does not change meaningfully with increases in either [CuT] or [L], meaning that Cu²⁺ substitution in Ca²⁺ valence sites in precipitating CaCO₃ speleothems is likely to be inhibited by organic complexation. We suggest that the residence time of speleothem thin water films (1/drip rate), the dissociation rates of labile metal-organic complexes, and the stability of adsorbed (ternary) metal-organic complexes will determine M²⁺ incorporation in speleothems.

year: 2018

title: Alum dosing effects on fish and aquatic invertebrates: Utuhina Stream 2024

authors: Ling, Nicholas

abstract: To reduce external phosphorus loading to Lake Rotorua, the Bay of Plenty Regional Council has been granted resource consent to dose the Utuhina Stream with alum (aluminium sulphate). Aluminium binds phosphorus, preventing its uptake by phytoplankton and thereby inhibiting growth. Aluminium forms monomeric species outside of circum-neutral pH (pH 68), and these species can disrupt osmoregulation and respiration of aquatic organisms. The alum dose rate to the Utuhina Stream is dependent on discharge, with a maximum application rate of 1 mg Al L-1. This report presents the results of an on-going assessment of the fish and aquatic macroinvertebrate communities of the Utuhina Stream for 2024.  Macroinvertebrates, fish and kōura (freshwater crayfish; Paranephrops planifrons) were sampled from one control (site 1) and two treatment (sites 2 & 3) reaches of the Utuhina Stream. Common bully (Gobiomorphus cotidianus) were the dominant species of the fish community, with juvenile trout and kōaro (Galaxias brevipinnis) also captured. Kōura were present at all sites but variable in abundance. There was a notable decline in the semiquantitative macroinvertebrate community (for soft-bottomed streams; MCI-sb) score at Sites 1 and 3 in 2024 compared to long-term site averages, with Site 1 declining into the ‘poor’ category. Interannual variation in MCI-sb scores is typical for these reaches of the Utuhina Stream and have been attributed to flood-related disturbances to stream bank morphology and in-stream vegetative cover (Ling 2021). Tissue aluminium concentrations were determined from common bully (flesh, gill, liver) and kōura (flesh, gill, hepatopancreas) by inductively coupled plasma mass spectrometry (ICP-MS). There was some evidence of aluminium bioaccumulation in the liver tissues of common bully at Site 2, but overall concentrations were similar to long-term averages and there were no notable differences for the same tissues between sites. Kōura tissue aluminium concentrations for 2024 were similar to long-term averages across all tissues and sites. A small number of individuals had elevated gill concentrations at Site 3 compared to long-term average concentrations, but this is unlikely to result in harmful physiological impacts. The data presented in this report further supports the conclusion by Tempero and Ling (2024) that alum dosing does not appear to have a notable effect on the fish and kōura community and that site and interannual differences appear to be due to hydrological and habitat variability.

text: Alum dosing effects on fish and aquatic invertebrates: Utuhina Stream 2024 To reduce external phosphorus loading to Lake Rotorua, the Bay of Plenty Regional Council has been granted resource consent to dose the Utuhina Stream with alum (aluminium sulphate). Aluminium binds phosphorus, preventing its uptake by phytoplankton and thereby inhibiting growth. Aluminium forms monomeric species outside of circum-neutral pH (pH 68), and these species can disrupt osmoregulation and respiration of aquatic organisms. The alum dose rate to the Utuhina Stream is dependent on discharge, with a maximum application rate of 1 mg Al L-1. This report presents the results of an on-going assessment of the fish and aquatic macroinvertebrate communities of the Utuhina Stream for 2024.  Macroinvertebrates, fish and kōura (freshwater crayfish; Paranephrops planifrons) were sampled from one control (site 1) and two treatment (sites 2 & 3) reaches of the Utuhina Stream. Common bully (Gobiomorphus cotidianus) were the dominant species of the fish community, with juvenile trout and kōaro (Galaxias brevipinnis) also captured. Kōura were present at all sites but variable in abundance. There was a notable decline in the semiquantitative macroinvertebrate community (for soft-bottomed streams; MCI-sb) score at Sites 1 and 3 in 2024 compared to long-term site averages, with Site 1 declining into the ‘poor’ category. Interannual variation in MCI-sb scores is typical for these reaches of the Utuhina Stream and have been attributed to flood-related disturbances to stream bank morphology and in-stream vegetative cover (Ling 2021). Tissue aluminium concentrations were determined from common bully (flesh, gill, liver) and kōura (flesh, gill, hepatopancreas) by inductively coupled plasma mass spectrometry (ICP-MS). There was some evidence of aluminium bioaccumulation in the liver tissues of common bully at Site 2, but overall concentrations were similar to long-term averages and there were no notable differences for the same tissues between sites. Kōura tissue aluminium concentrations for 2024 were similar to long-term averages across all tissues and sites. A small number of individuals had elevated gill concentrations at Site 3 compared to long-term average concentrations, but this is unlikely to result in harmful physiological impacts. The data presented in this report further supports the conclusion by Tempero and Ling (2024) that alum dosing does not appear to have a notable effect on the fish and kōura community and that site and interannual differences appear to be due to hydrological and habitat variability.

year: 2025

title: Poi Apakura

authors: Maxwell, Te Kahautu

abstract: Poi Apakura portrays the battles both pre European contact through to the land wars and the confiscation of 400,000 acres of Te Whakatōhea land s in 1865 with the killing of the missionary Rev Catl Volkner known as Te Wākana. Performed by Ōpōtiki Mai Tawhiti at the Te Matatini World Championship Kapa Haa Competition 2013.

text: Poi Apakura Poi Apakura portrays the battles both pre European contact through to the land wars and the confiscation of 400,000 acres of Te Whakatōhea land s in 1865 with the killing of the missionary Rev Catl Volkner known as Te Wākana. Performed by Ōpōtiki Mai Tawhiti at the Te Matatini World Championship Kapa Haa Competition 2013.

year: 2013