title: The link between erosion, phosphorus and water quality

authors: Gibbs, Max M.

abstract: In lakes, the solubility of phosphorus (P) in water, and therefore its availability to aquatic plants (macrophytes and algae) for growth, is controlled by oxygen and pH. The supply of dissolved reactive P (DRP) to the lake water column is mostly from sediment release from
decomposing plant material and iron oxides during periods of low oxygen, although in Lake Rotorua and most of the other lakes on the central volcanic plateau, spring-fed streams carry relatively high concentrations of DRP into the lakes. The mechanism for releasing iron-bound DRP from the sediment focusses around the oxidation state iron (Fe) and manganese (Mn). In well oxygenated conditions iron exists in the oxidised state as ferric ions which form ferric oxides that are insoluble in water. These oxides sequester DRP as they precipitate and remove it from the water column. When the oxygen concentration falls to zero (anoxic conditions) iron exists in the reduced state as ferrous ions, which are soluble in water. As the ferric form reduces to the ferrous form it dissolves and the DRP bound to the iron is released into the water column where it is used by algae for growth. The algae eventually senesce and die, returning the P to the sediment as particulate P, where it can be recycled during the next period of anoxia.
Apart from recycling of algal biomass, P also comes from the catchment, bound to the iron oxides in soil particles. The P content of the soil is greatest in the finest soil particles, which are the first to be eroded by rainfall and do not settle until they reach the calm waters of a lake. There they augment the P load from the senescing algal biomass, thereby increasing the amount of DRP that can be released during the next anoxic event. Because of the high background concentration of dissolved inorganic nitrogen in the lake water, the addition of any DRP will stimulate algal growth and thus result in a deterioration of lake water quality. Land management strategies to reduce soil erosion include changes to the way land is farmed and the interception and retention of fine sediment using detention bunds.

text: The link between erosion, phosphorus and water quality In lakes, the solubility of phosphorus (P) in water, and therefore its availability to aquatic plants (macrophytes and algae) for growth, is controlled by oxygen and pH. The supply of dissolved reactive P (DRP) to the lake water column is mostly from sediment release from
decomposing plant material and iron oxides during periods of low oxygen, although in Lake Rotorua and most of the other lakes on the central volcanic plateau, spring-fed streams carry relatively high concentrations of DRP into the lakes. The mechanism for releasing iron-bound DRP from the sediment focusses around the oxidation state iron (Fe) and manganese (Mn). In well oxygenated conditions iron exists in the oxidised state as ferric ions which form ferric oxides that are insoluble in water. These oxides sequester DRP as they precipitate and remove it from the water column. When the oxygen concentration falls to zero (anoxic conditions) iron exists in the reduced state as ferrous ions, which are soluble in water. As the ferric form reduces to the ferrous form it dissolves and the DRP bound to the iron is released into the water column where it is used by algae for growth. The algae eventually senesce and die, returning the P to the sediment as particulate P, where it can be recycled during the next period of anoxia.
Apart from recycling of algal biomass, P also comes from the catchment, bound to the iron oxides in soil particles. The P content of the soil is greatest in the finest soil particles, which are the first to be eroded by rainfall and do not settle until they reach the calm waters of a lake. There they augment the P load from the senescing algal biomass, thereby increasing the amount of DRP that can be released during the next anoxic event. Because of the high background concentration of dissolved inorganic nitrogen in the lake water, the addition of any DRP will stimulate algal growth and thus result in a deterioration of lake water quality. Land management strategies to reduce soil erosion include changes to the way land is farmed and the interception and retention of fine sediment using detention bunds.

year: 2015

title: Human activities shape global patterns of decomposition rates in rivers

authors: Tiegs, S.D.

subjects: CELLDEX Consortium‡

abstract: Rivers and streams contribute to global carbon cycling by decomposing immense quantities of terrestrial plant matter. However, decomposition rates are highly variable and large-scale patterns and drivers of this process remain poorly understood. Using a cellulose-based assay to reflect the primary constituent of plant detritus, we generated a predictive model (81% variance explained) for cellulose decomposition rates across 514 globally distributed streams. A large number of variables were important for predicting decomposition, highlighting the complexity of this process at the global scale. Predicted cellulose decomposition rates, when combined with genus-level litter quality attributes, explain published leaf litter decomposition rates with high accuracy (70% variance explained). Our global map provides estimates of rates across vast understudied areas of Earth and reveals rapid decomposition across continental-scale areas dominated by human activities.

text: Human activities shape global patterns of decomposition rates in rivers Rivers and streams contribute to global carbon cycling by decomposing immense quantities of terrestrial plant matter. However, decomposition rates are highly variable and large-scale patterns and drivers of this process remain poorly understood. Using a cellulose-based assay to reflect the primary constituent of plant detritus, we generated a predictive model (81% variance explained) for cellulose decomposition rates across 514 globally distributed streams. A large number of variables were important for predicting decomposition, highlighting the complexity of this process at the global scale. Predicted cellulose decomposition rates, when combined with genus-level litter quality attributes, explain published leaf litter decomposition rates with high accuracy (70% variance explained). Our global map provides estimates of rates across vast understudied areas of Earth and reveals rapid decomposition across continental-scale areas dominated by human activities.

year: 2024

title: Tito Waiata-Tito Pūoro: extending the Kīngitanga music tradition.

authors: Rollo, Te Manaaroha Pirihira

subjects: Kīngitanga

abstract: Since 1858, music has always been an integral part of the Kīngitanga movement in New Zealand. As this music tradition evolves with the introduction of new musical idioms, genres and digital technology, so too do the practices of composing new works. 

The objective of this research was to construct a model for combining waiata, taonga pūoro and New Zealand electroacoustic music, in order to create new works that enhance the Kīngitanga music tradition.  Developing a model for composing and integrating these idioms within a Māori context presented problems, as traditional Māori music conflict with contemporary Western forms. 

To generate a framework and practical model for composing hybrid music, an examination of selected New Zealand works was first carried out through: a) the collection of 50 traditional and contemporary waiata relating to the Kīngitanga b) the collection of 10 New Zealand taonga pūoro works and c) a collection of 10 New Zealand electroacoustic music. An analysis of the music and compositional processes of each idiom implementing the ‘de-construct in order to re-construct’ approach to understand how they work musically and compositionally was accomplished. 

To demonstrate the outcome of my models, six original compositions were presented exploring different aspects of musical composition. These models focused on sound architecture and explored a) communicative relationships between composer, performer, and audience b) Holistic Co-hear-ence, implementing the horizontal and vertical layering model, and c) technical approaches using digital technology. To comply with Māori principles of composition and performance, each model and new work demonstrated Kaupapa Māori , Wairua  and Te Mana - Te Ihi - Te Wehi - Te Tapu . 

The findings and original contributions of this research provide a model that combines two musical traditions and three music idioms, and in turn, may guide contemporary composers in creating new works that extend the Kīngitanga music tradition.

text: Tito Waiata-Tito Pūoro: extending the Kīngitanga music tradition. Since 1858, music has always been an integral part of the Kīngitanga movement in New Zealand. As this music tradition evolves with the introduction of new musical idioms, genres and digital technology, so too do the practices of composing new works. 

The objective of this research was to construct a model for combining waiata, taonga pūoro and New Zealand electroacoustic music, in order to create new works that enhance the Kīngitanga music tradition.  Developing a model for composing and integrating these idioms within a Māori context presented problems, as traditional Māori music conflict with contemporary Western forms. 

To generate a framework and practical model for composing hybrid music, an examination of selected New Zealand works was first carried out through: a) the collection of 50 traditional and contemporary waiata relating to the Kīngitanga b) the collection of 10 New Zealand taonga pūoro works and c) a collection of 10 New Zealand electroacoustic music. An analysis of the music and compositional processes of each idiom implementing the ‘de-construct in order to re-construct’ approach to understand how they work musically and compositionally was accomplished. 

To demonstrate the outcome of my models, six original compositions were presented exploring different aspects of musical composition. These models focused on sound architecture and explored a) communicative relationships between composer, performer, and audience b) Holistic Co-hear-ence, implementing the horizontal and vertical layering model, and c) technical approaches using digital technology. To comply with Māori principles of composition and performance, each model and new work demonstrated Kaupapa Māori , Wairua  and Te Mana - Te Ihi - Te Wehi - Te Tapu . 

The findings and original contributions of this research provide a model that combines two musical traditions and three music idioms, and in turn, may guide contemporary composers in creating new works that extend the Kīngitanga music tradition.

year: 2014