Based on a qualitative study of four organisations involving 47 respondents following the extensive 2010 – 2011 earthquakes in Christchurch, New Zealand, this paper presents some guidance for human resource practitioners dealing with post-disaster recovery. A key issue is the need for the human resource function to reframe its practices in a post-disaster context, developing a specific focus on understanding and addressing changing employee needs, and monitoring the leadership behaviour of supervisors. This article highlights the importance of flexible organisational responses based around a set of key principles concerning communication and employee perceptions of company support.
This thesis set out to explore the experiences of clients and counsellors in immediate crisis intervention shortly after a major earthquake. It explored the experiences and perceptions of change during counselling for both clients and counsellor, all of which were exposed to the disaster. This study supported the idea of counsellors needing to adapt to the context of post-disaster counselling and addressing client’s immediate needs. Having both been through the same disaster meant counsellors were often going through similar experiences and emotions as their clients during this time. This led counsellors to develop a greater sense of connection and understanding of their client, as well as showing more emotional responsivity and self-disclosure. This was experienced as different to their normal therapy engagement. The implications of these counsellor responses were seen to be helpful, but at times had the potential to be hindering for counselling. Clients valued their counsellor’s techniques and personal qualities but often failed to identify what contribution they, themselves, made to change processes. The differing nature of counselling in post-disaster areas, as gauged by this study may help inform expectations and experiences regarding provision of post-disaster acute interventions.
A selection of the week's news including a former New Zealand cricketer demanding answers over how his name has been linked an investigation into match-fixing, the Act Party leader announces he is quitting as party leader and will leave parliament next year, the biggest drug haul in New Zealand history, the Auditor General apologises to Mangawhai locals for Audit New Zealand's failure to identify a 60 million-plus waste-water debacle, the Labour Party says its victory in the Christchurch East by-election is an indictment of the Government's response to the earthquakes, we hear from the author of a book about the building blocks of our words and literature and the national champion who will proudly represent New Zealand at an international competition in Perth.
Disasters are rare events with major consequences; yet comparatively little is known about managing employee needs in disaster situations. Based on case studies of four organisations following the devastating earthquakes of 2010 - 2011 in Christchurch, New Zealand, this paper presents a framework using redefined notions of employee needs and expectations, and charting the ways in which these influence organisational recovery and performance. Analysis of in-depth interview data from 47 respondents in four organisations highlighted the evolving nature of employee needs and the crucial role of middle management leadership in mitigating the effects of disasters. The findings have counterintuitive implications for human resource functions in a disaster, suggesting that organisational justice forms a central framework for managing organisational responses to support and engage employees for promoting business recovery.
The Avon-Heathcote Estuary is of significant value to Christchurch due to its high productivity, biotic diversity, proximity to the city, and its cultural, recreational and aesthetic qualities. Nonetheless, it has been subjected to decades of degradation from sewage wastewater discharges and encroaching urban development. The result was a eutrophied estuary, high in nitrogen, affected by large blooms of nuisance macroalgae and covered by degraded sediments. In March 2010, treated wastewater was diverted from the estuary to a site 3 km offshore. This quickly reduced water nitrogen by 90% within the estuary and, within months, there was reduced production of macroalgae. However, a series of earthquakes beginning in September 2010 brought massive changes: tilting of the estuary, changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sediment and nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are an important buffer against eutrophication. Therefore, in tandem with the wastewater diversion, they could underpin much of the recovery of the estuary. Overall, the new sediments were less favourable for benthic microalgal growth and recolonisation, but were less contaminated than old sediments at highly eutrophic sites. Because the new sediments were less contaminated than the old sediments, they could help return the estuary to a noneutrophic state. However, if the new sediments, which are less favourable for microalgal growth, disperse over the old sediments at highly eutrophic sites, they could become contaminated and interfere with estuarine recovery. Therefore, recovery of microalgal communities and the estuary was expected to be generally long, but variable and site-specific, with the least eutrophic sites recovering quickly, and the most eutrophic sites taking years to return to a pre-earthquake and non-eutrophied state. changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sedimen tand nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are
This report presents an overview of the soil profile characteristics at a number of strong motion station (SMS) sites in Christchurch and its surrounds. An extensive database of ground motion records has been captured by the SMS network in the Canterbury region during the Canterbury earthquake sequence. However in order to comprehensively understand the ground motions recorded at these sites and to be able to relate these motions to other locations, a detailed understanding of the shallow geotechnical profile at each SMS is required. The original NZS1170.5 (SNZ 2004) site subsoil classifications for each SMS site is based on regional geological information and well logs located at varying distances from the site. Given the variability of Christchurch soils, more detailed investigations are required in close vicinity to each SMS to better understand stratigraphy and soil properties, which are important in seismic site response. In this regard, CPT, SPT and borehole data, shear wave velocity (Vs) profiles, and horizontal to vertical spectral ratio measurements (H/V) in close vicinity to the SMS were used to develop representative soil profiles at each site. NZS1170.5 (SNZ 2004) site subsoil classifications were updated using Vs and SPT N60 criteria. Site class E boundaries were treated as a sliding scale rather than as a discrete boundary to account for locations with similar site effects potential, an approach which was shown to result in a better delineation between the site classes. SPT N60 values often indicate a stiffer site class than the Vs data for softer soil sites, highlighting the disparity between the two site investigation techniques. Both SPT N60 and Vs based site classes did not always agree with the original site classifications. This emphasises the importance of having detailed site‐specific information at SMS locations in order to properly classify them. Furthermore, additional studies are required to harmonize site classification based on SPT N60 and Vs. Liquefaction triggering assessments were carried out for the Darfield and Christchurch earthquakes, and compared against observed liquefaction surface manifestations and ground motions characteristics at each SMS. In general, the characteristics of the recorded ground motions at each site correlate well with the triggering analyses. However, at sites that likely liquefied at depth (as indicated by triggering analyses and/or inferred from the characteristics of the recorded surface acceleration time series), the presence of a non‐liquefiable crust layer at many of the SMS locations prevented the manifestation of any surface effects.
Fine grained sediment deposition in urban environments during natural hazard events can impact critical infrastructure and properties (urban terrain) leading to reduced social and economic function and potentially adverse public health effects. Therefore, clean-up of the sediments is required to minimise impacts and restore social and economic functionality as soon as possible. The strategies employed to manage and coordinate the clean-up significantly influence the speed, cost and quality of the clean-up operation. Additionally, the physical properties of the fine grained sediment affects the clean-up, transport, storage and future usage of the sediment. The goals of the research are to assess the resources, time and cost required for fine grained sediment clean-up in an urban environment following a disaster and to determine how the geotechnical properties of sediment will affect urban clean-up strategies. The thesis focuses on the impact of fine grained sediment (<1 mm) deposition from three liquefaction events during the Canterbury earthquake sequence (2010-2011) on residential suburbs and transport networks in Christchurch. It also presents how geotechnical properties of the material may affect clean-up strategies and methods by presenting geotechnical analysis of tephra material from the North Island of New Zealand. Finally, lessons for disaster response planning and decision making for clean-up of sediment in urban environments are presented. A series of semi-structured interviews of key stakeholders supported by relevant academic literature and media reports were used to record the clean-up operation coordination and management and to make a preliminary qualification of the Christchurch liquefaction ejecta clean-up (costs breakdown, time, volume, resources, coordination, planning and priorities). Further analysis of the costs and resources involved for better accuracy was required and so the analysis of Christchurch City Council road management database (RAMM) was done. In order to make a transition from general fine sediment clean-up to specific types of fine disaster sediment clean-up, adequate information about the material properties is required as they will define how the material will be handled, transported and stored. Laboratory analysis of young volcanic tephra from the New Zealand’s North Island was performed to identify their geotechnical properties (density, granulometry, plasticity, composition and angle of repose). The major findings of this research were that emergency planning and the use of the coordinated incident management system (CIMS) system during the emergency were important to facilitate rapid clean-up tasking, management of resources and ultimately recovery from widespread and voluminous liquefaction ejecta deposition in eastern Christchurch. A total estimated cost of approximately $NZ 40 million was calculated for the Christchurch City clean-up following the 2010-2011 Canterbury earthquake sequence with a partial cost of $NZ 12 million for the Southern part of the city, where up to 33% (418 km) of the road network was impacted by liquefaction ejecta and required clearing of the material following the 22 February 2011 earthquake. Over 500,000 tonnes of ejecta has been stockpiled at Burwood landfill for all three liquefaction inducing earthquake events. The average cost per kilometre for the event clean-up was $NZ 5,500/km (4 September 2010), $NZ 11,650/km (22 February 2011) and $NZ 11,185/km (13 June 2011). The duration of clean-up time of residential properties and the road network was approximately two to three months for each of the three liquefaction ejecta events; despite events volumes and spatial distribution of ejecta. Interviews and quantitative analysis of RAMM data revealed that the experience and knowledge gained from the Darfield earthquake (4 September 2010) clean-up increased the efficiency of the following Christchurch earthquake induced liquefaction ejecta clean-up events. Density, particle size, particle shape, clay content and moisture content, are the important geotechnical properties that need to be considered when planning for a clean-up method that incorporates collection, transport and disposal or storage. The geotechnical properties for the tephra samples were analysed to increase preparedness and reaction response of potentially affected North Island cities from possible product from the active volcanoes in their region. The geotechnical results from this study show that volcanic tephra could be used in road or construction material but the properties would have to be further investigated for a New Zealand context. Using fresh volcanic material in road, building or flood control construction requires good understanding of the material properties and precaution during design and construction to extra care, but if well planned, it can be economically beneficial.
Disasters are rare events with major consequences; yet comparatively little is known about managing employee needs in disaster situations. Based on case studies of four organisations following the devastating earthquakes of 2010 - 2011 in Christchurch, New Zealand, this paper presents a framework using redefined notions of employee needs and expectations, and charting the ways in which these influence organisational recovery and performance. Analysis of in-depth interview data from 47 respondents in four organisations highlighted the evolving nature of employee needs and the crucial role of middle management leadership in mitigating the effects of disasters. The findings have counterintuitive implications for human resource functions in a disaster, suggesting that organisational justice forms a central framework for managing organisational responses to support and engage employees for promoting business recovery.
Rt Hon WINSTON PETERS to the Prime Minister: Does he stand by all his statements?
DAVID SHEARER to the Prime Minister: Does he stand by all his statements?
PAUL GOLDSMITH to the Minister of Finance: What reports has he received on business and economic conditions in New Zealand?
Dr RUSSEL NORMAN to the Prime Minister: Does he stand by his answer to written question 07314 (2013) when he said: "The inquiry team, itself, did not seek permission from Peter Dunne before it obtained his email logs" and does he think it should have?
SIMON O'CONNOR to the Minister of Transport: How will the Government progress the delivery of the next generation of transport projects for Auckland?
Hon DAVID PARKER to the Minister of Finance: Are the proceeds from selling power companies and other assets being used to pay down debt, to build schools and hospitals, to fund irrigation projects, to rebuild Christchurch, or to fund Auckland transport projects?
IAN McKELVIE to the Minister of Police: What updates has she received on how Police are using technology to prevent crime?
JACINDA ARDERN to the Minister of Finance: Does he agree with The Economist that "inequality is one of the biggest social, economic and political challenges of our time"; if so, what is his Government doing to address the fact that New Zealand now has the widest income gap since detailed records began?
PAUL FOSTER-BELL to the Minister of Justice: How is the Government improving its justice and other services to local communities?
Hon LIANNE DALZIEL to the Minister for Canterbury Earthquake Recovery: When was he first made aware of the September IANZ report which warned the Christchurch City Council that "Continued accreditation beyond May 2013 will depend on a satisfactory outcome of that assessment" and was he advised by CERA or a Ministerial colleague?
JONATHAN YOUNG to the Minister of Broadcasting: What progress has been made on the regional rollout of the digital switchover for New Zealand television viewers?
GARETH HUGHES to the Minister of Conservation: Will he implement the recommendations to protect Maui's dolphins contained in the report of this year's meeting of the International Whaling Commission Scientific Committee; if not, why not
Questions to Members
JACINDA ARDERN to the Chairperson of the Social Services Committee: On which date and time, if any, did he receive the Minister for Social Development's written responses to the pre-hearing questions for the 2013/14 Estimates review for Vote Social Development?
JACINDA ARDERN to the Chairperson of the Social Services Committee: On what date did the Minister for Social Development appear before the Committee to answer questions regarding the 2013/14 Estimates review for Vote Social Development?
Dr MEGAN WOODS to the Chairperson of the Education and Science Committee: Did he consider inviting the Minister to appear again to answer questions around responses to questions on the 2013/14 Estimates for Vote Education, if so, did he receive any advice about the Minister's willingness to appear again?
Questions to Ministers
Hon DAVID PARKER to the Minister of Finance: Does he stand by his statement that a publicly-owned insurer is a "dumb idea"?
Dr RUSSEL NORMAN to the Prime Minister: Does he stand by all his statements regarding Government policy?
Hon TAU HENARE to the Minister of Finance: What reports has he received on the economy – and especially on further signs of improving economic momentum and increasing business and consumer confidence?
Hon SHANE JONES to the Prime Minister: Does he have confidence in his Ministers?
Hon PETER DUNNE to the Minister of Foreign Affairs: What advice has he received on the call from Amnesty International opposing the appointment of Sri Lankan President Mahinda Rajapaksa as Chair of the Commonwealth for the next two years, and host of next week's Commonwealth Heads of Government meeting?
Hon CLAYTON COSGROVE to the Minister responsible for the Earthquake Commission: Does he still believe that New Zealanders can have confidence in EQC?
MARK MITCHELL to the Minister of Commerce: What steps is the Government taking to introduce more competition into the housing construction market?
JAN LOGIE to the Minister of Justice: When she said, in response to whether the pre-trial and trial process precludes some sexual violence victims from complaining "quite clearly, it does not"; did she mean that few sexual violence victims are deterred from complaining by the process itself?
Rt Hon WINSTON PETERS to the Prime Minister: Does he have confidence in the Minister for State Owned Enterprises?
JACQUI DEAN to the Minister of Corrections: What recent announcements has she made on the redevelopment of prison facilities?
PHIL TWYFORD to the Minister of Housing: Does he stand by his statement that the housing situation in Christchurch is "a challenge, not a crisis"?
CHRIS AUCHINVOLE to the Minister for Arts, Culture and Heritage: How does the Government intend to mark the centenary of the First World War?
In the aftermath of the 2011 earthquake, a state of polycentric urbanity was thrust upon New Zealand’s second largest city. As the city-centre lay in disrepair, smaller centres started to materialise elsewhere, out of necessity. Transforming former urban peripheries and within existing suburbs into a collective, dispersed alternative to the city centre, these sub-centres prompted a range of morphological, socio-cultural and political transformations, and begged multiple questions: how to imbue these new sub-centres with gravity? How to render them a genuine alternative to the CBD? How do they operate within the wider city? How to cope with the physical and cultural transformations of this shifting urbanscape and prevent them occurring ad lib? Indeed, the success and functioning of the larger urban structure hinges upon a critical, informed response to these sub-centre urban contexts. Yet, with an unrelenting focus on the CBD rebuild - effectively a polycentric denial - little such attention has been granted. Taking this urban condition as its premise and its provocation, this thesis investigates architecture’s role in the emergent sub-centre. It asks: what can architecture do in these urban contexts; how can architecture act upon the emergent sub-centre in a critical, catalytic fashion? Identifying this volatile condition as both an opportunity for architectural experimentation and a need for critical architectural engagement, this thesis seeks to explore the sub-centre (as an idea and actual urban context) as architecture’s project: its raison d’etre, impetus and aspiration. These inquiries are tested through design-led research: an initial design question provoking further, broader discursive research (and indeed, seeking broader implications). The first section is a site-specific, design for Sumner, Christchurch. Titled ‘An Agora Anew’; this project - both in conception and outcome - is a speculative response to a specific sub-centre condition. The second section ‘The Sub-centre as Architecture’s Project’ explores the ideas provoked by the design project within a discursive framework. Firstly it identifies the sub-centre as a context in desperate need of architectural attention (why architecture?); secondly, it negotiates a possible agenda for architecture in this context through terms of engagement that are formal, critical and opportunistic (how architecture?): enabling it to take a position on and in the sub-centre. Lastly, a critical exegesis positions the design in regards to the broader discursive debate: critiquing it an architectural project predicated upon the idea of the sub-centre. The implications of this design-led thesis are twofold: firstly, for architecture’s role in the sub-centre (especially to Christchurch); secondly for the possibilities of architecture’s productive engagement with the city (largely through architectural form), more generally. In a century where radical, new urban contexts (of which the sub-centre is just one) are commonplace, this type of thinking – what can architecture do in the city? - is imperative.
Hon PHIL HEATLEY to the Minister of Finance: What reports has he received on the economy – and especially on further signs of economic momentum in the regions and among manufacturers?
Dr RUSSEL NORMAN to the Minister of Finance: How much did the Government's share sales in Mighty River Power, Meridian, and Air New Zealand raise, given that the Supplement to the 2010 Investment Statement of the Government of New Zealand projected that those sales would raise $5.18 billion?
Hon DAVID PARKER to the Minister for ACC: How much did ACC invest in Pike River Coal Limited and in New Zealand Oil and Gas Limited over the last eight years, and how much has it made or lost in total on its investment in each company, taking into account share purchases, subscriptions and sales, dividends, and current share prices?
Rt Hon WINSTON PETERS to the Minister of Māori Affairs: Does he stand by his statement "I know Māori want to talk about the place of the Treaty of Waitangi in our constitution, and how our legal and political systems can reflect tikanga Māori."; if so, why?
Hon SHANE JONES to the Associate Minister of Finance: Is he satisfied with his performance in regard to his delegations as Associate Minister of Finance?
JONATHAN YOUNG to the Minister for Building and Construction: What reports has he received regarding the state of the building and construction sector?
GARETH HUGHES to the Minister for the Environment: Did the Environmental Protection Authority assess the full version of Anadarko's Discharge Management Plan and Emergency Response Plan as part of its evaluation of the company's Environmental Impact Assessment for the Deepwater Taranaki Well; if not, why not?
Hon CLAYTON COSGROVE to the Minister of Finance: When, if at all, did Cabinet approve the timing of the Air New Zealand sell-down and what directions did Cabinet give the shareholding Ministers?
NICKY WAGNER to the Minister of Housing: What steps is the Government taking to rebuild Christchurch's housing stock damaged or destroyed by the earthquakes?
Hon DAMIEN O'CONNOR to the Minister for Primary Industries: Does he stand by his statement "The opportunity, and challenge, for our meat producers now is to add value to different cuts of meat and continue to sell the New Zealand story"; if so, why?
IAN McKELVIE to the Minister of Local Government: How is the Government improving councils' financial reporting?
DARIEN FENTON to the Minister of Labour: Does he stand by his statement that "I am especially keen to hear what affected parties have to say on the Part 6A proposals in the Bill, and will carefully consider their submissions and the recommendations of the select committee"?
Mitigating the cascade of environmental damage caused by the movement of excess reactive nitrogen (N) from land to sea is currently limited by difficulties in precisely and accurately measuring N fluxes due to variable rates of attenuation (denitrification) during transport. This thesis develops the use of the natural abundance isotopic composition of nitrate (δ15N and δ18O of NO₃-) to integrate the spatialtemporal variability inherent to denitrification, creating an empirical framework for evaluating attenuation during land to water NO₃- transfers. This technique is based on the knowledge that denitrifiers kinetically discriminate against 'heavy' forms of both N and oxygen (O), creating a parallel enrichment in isotopes of both species as the reaction progresses. This discrimination can be quantitatively related to NO₃- attenuation by isotopic enrichment factors (εdenit). However, while these principles are understood, use of NO₃- isotopes to quantify denitrification fluxes in non-marine environments has been limited by, 1) poor understanding of εdenit
variability, and, 2) difficulty in distinguishing the extent of mixing of isotopically distinct sources from the
imprint of denitrification. Through a combination of critical literature analysis, mathematical modelling, mesocosm to field scale experiments, and empirical studies on two river systems over distance and time, these short comings are parametrised and a template for future NO₃- isotope based attenuation measurements
outlined.
Published εdenit values (n = 169) are collated in the literature analysis presented in Chapter 2. By evaluating these values in the context of known controllers on the denitrification process, it is found that the magnitude of εdenit, for both δ15N and δ18O, is controlled by, 1) biology, 2) mode of transport through the denitrifying zone (diffusion v. advection), and, 3) nitrification (spatial-temporal distance between nitrification and denitrification). Based on the outcomes of this synthesis, the impact of the three factors identified as controlling εdenit are quantified in the context of freshwater systems by combining simple mathematical modelling and lab incubation studies (comparison of natural variation in biological versus physical expression). Biologically-defined εdenit, measured in sediments collected from four sites along a temperate stream and from three tropical submerged paddy fields, varied from -3‰ to -28‰ depending on the site’s antecedent carbon content. Following diffusive transport to aerobic surface water, εdenit was found to
become more homogeneous, but also lower, with the strength of the effect controlled primarily by diffusive distance and the rate of denitrification in the sediments. I conclude that, given the variability in fractionation dynamics at all levels, applying a range of εdenit from -2‰ to -10‰ provides more accurate measurements of attenuation than attempting to establish a site-specific value. Applying this understanding of denitrification's fractionation dynamics, four field studies were conducted to measure denitrification/ NO₃- attenuation across diverse terrestrial → freshwater systems. The development of NO₃- isotopic signatures (i.e., the impact of nitrification, biological N fixation, and ammonia volatilisation on the isotopic 'imprint' of denitrification) were evaluated within two key agricultural regions: New Zealand grazed pastures (Chapter 4) and Philippine lowland submerged rice production (Chapter 5). By measuring the isotopic composition of soil ammonium, NO₃- and volatilised ammonia following the bovine urine deposition, it was determined that the isotopic composition of NO₃ - leached from grazed pastures is defined by the balance between nitrification and denitrification, not ammonia volatilisation. Consequently, NO₃- created within pasture systems was predicted to range from +10‰ (δ15N)and -0.9‰ (δ18O) for non-fertilised fields (N limited) to -3‰ (δ15N) and +2‰ (δ18O) for grazed fertilised fields (N saturated). Denitrification was also the dominant determinant of NO₃- signatures in the Philippine rice paddy. Using a site-specific εdenit for the paddy, N inputs versus attenuation were able to be calculated, revealing that >50% of available N in the top 10 cm of soil was denitrified during land preparation, and >80% of available N by two weeks post-transplanting. Intriguingly, this denitrification was driven by rapid
NO₃- production via nitrification of newly mineralised N during land preparation activities.
Building on the relevant range of εdenit established in Chapters 2 and 3, as well as the soil-zone confirmation that denitrification was the primary determinant of NO₃- isotopic composition, two long-term
longitudinal river studies were conducted to assess attenuation during transport. In Chapter 6, impact and recovery dynamics in an urban stream were assessed over six months along a longitudinal impact gradient using measurements of NO₃- dual isotopes, biological populations, and stream chemistry. Within 10 days of the catastrophic Christchurch earthquake, dissolved oxygen in the lowest reaches was <1 mg l⁻¹, in-stream denitrification accelerated (attenuating 40-80% of sewage N), microbial biofilm communities changed, and several benthic invertebrate taxa disappeared. To test the strength of this method for tackling the diffuse, chronic N loading of streams in agricultural regions, two years of longitudinal measurements of NO₃- isotopes were collected. Attenuation was negatively correlated with NO₃- concentration, and was highly
dependent on rainfall: 93% of calculated attenuation (20 kg NO₃--N ha⁻¹ y⁻¹) occurred within 48 h of rainfall.
The results of these studies demonstrate the power of intense measurements of NO₃- stable isotope for distinguishing temporal and spatial trends in NO₃ - loss pathways, and potentially allow for improved catchment-scale management of agricultural intensification. Overall this work now provides a more cohesive understanding for expanding the use of NO₃- isotopes measurements to generate accurate understandings of the controls on N losses. This information is becoming increasingly important to predict ecosystem response to future changes, such the increasing agricultural intensity needed to meet global food demand, which is occurring synergistically with unpredictable global climate change.
