title: Nitrogen fixation in the New Zealand mangrove (Avicennia marina (Forsk.) Vierh. var. resinifera (Forst f.) Bakh.)

authors: Hicks, Brendan J.

subjects: biology

abstract: Nitrogenase activity in mangrove forests at two locations in the North Island, New Zealand, was measured by acetylene reduction and 15N2 uptake. Nitrogenase activity (C2H2 reduction) in surface sediments 0 to 10 mm deep was highly correlated (r = 0.91, n = 17) with the dry weight of decomposing particulate organic matter in the sediment and was independent of light. The activity was not correlated with the dry weight of roots in the top 10 mm of sediment (r = –0.01, n = 13). Seasonal and sample variation in acetylene reduction rates ranged from 0.4 to 50.0 µmol of C2H4 m–2 h–1 under air, and acetylene reduction was depressed in anaerobic atmospheres. Nitrogen fixation rates of decomposing leaves from the surface measured by 15N2 uptake ranged from 5.1 to 7.8 nmol of N2 g (dry weight)–1 h–1, and the mean molar ratio of acetylene reduced to nitrogen fixed was 4.5:1. Anaerobic conditions depressed the nitrogenase activity in decomposing leaves, which was independent of light. Nitrogenase activity was also found to be associated with pneumatophores. This activity was light dependent and was probably attributable to one or more species of Calothrix present as an epiphyte. Rates of activity were generally between 100 and 500 nmol of C2H4 pneumatophore–1 h–1 in summer, but values up to 1,500 nmol of C2H4 pneumatophore–1 h–1 were obtained.

text: Nitrogen fixation in the New Zealand mangrove (Avicennia marina (Forsk.) Vierh. var. resinifera (Forst f.) Bakh.) Nitrogenase activity in mangrove forests at two locations in the North Island, New Zealand, was measured by acetylene reduction and 15N2 uptake. Nitrogenase activity (C2H2 reduction) in surface sediments 0 to 10 mm deep was highly correlated (r = 0.91, n = 17) with the dry weight of decomposing particulate organic matter in the sediment and was independent of light. The activity was not correlated with the dry weight of roots in the top 10 mm of sediment (r = –0.01, n = 13). Seasonal and sample variation in acetylene reduction rates ranged from 0.4 to 50.0 µmol of C2H4 m–2 h–1 under air, and acetylene reduction was depressed in anaerobic atmospheres. Nitrogen fixation rates of decomposing leaves from the surface measured by 15N2 uptake ranged from 5.1 to 7.8 nmol of N2 g (dry weight)–1 h–1, and the mean molar ratio of acetylene reduced to nitrogen fixed was 4.5:1. Anaerobic conditions depressed the nitrogenase activity in decomposing leaves, which was independent of light. Nitrogenase activity was also found to be associated with pneumatophores. This activity was light dependent and was probably attributable to one or more species of Calothrix present as an epiphyte. Rates of activity were generally between 100 and 500 nmol of C2H4 pneumatophore–1 h–1 in summer, but values up to 1,500 nmol of C2H4 pneumatophore–1 h–1 were obtained.

year: 1985

title: Willingness-to-pay for renewable energy: Primary and discretionary choice of British households' for micro-generation technologies

authors: Scarpa, Riccardo

subjects: renewable energy

abstract: This paper documents the policy context of renewable energy production in the European Union. The research adopts a choice experiment approach to investigate households' WTP for these renewable energy technologies in the UK. The micro-generation technologies comprise solar photovoltaic, micro-wind, solar thermal, heat pumps, and biomass boilers and pellet stoves. The study compares the results from conditional and mixed logit models, which estimate the distribution of utility coefficients and then derives WTP values as a ratio of the attribute coefficient to the price coefficient, with a model in which the WTP distribution is estimated directly from utility in the money space. The results suggest that whilst renewable energy adoption is significantly valued by households, this value is not sufficiently large, for the vast majority of households, to cover the higher capital costs of micro-generation energy technologies.

text: Willingness-to-pay for renewable energy: Primary and discretionary choice of British households' for micro-generation technologies This paper documents the policy context of renewable energy production in the European Union. The research adopts a choice experiment approach to investigate households' WTP for these renewable energy technologies in the UK. The micro-generation technologies comprise solar photovoltaic, micro-wind, solar thermal, heat pumps, and biomass boilers and pellet stoves. The study compares the results from conditional and mixed logit models, which estimate the distribution of utility coefficients and then derives WTP values as a ratio of the attribute coefficient to the price coefficient, with a model in which the WTP distribution is estimated directly from utility in the money space. The results suggest that whilst renewable energy adoption is significantly valued by households, this value is not sufficiently large, for the vast majority of households, to cover the higher capital costs of micro-generation energy technologies.

year: 2010

title: He Maimai Aroha mō Nātana Waka Takurua

authors: Manuirirangi, Hōri

subjects: Poroporoaki

abstract: He kupu whakamānawa nā Hōri Manuirirangi ki a Nātana Waka Takurua i tana matenga.

text: He Maimai Aroha mō Nātana Waka Takurua He kupu whakamānawa nā Hōri Manuirirangi ki a Nātana Waka Takurua i tana matenga.

year: 2012-05