Aldrin Rivas

Doctor of Philosophy
Study Completed: 2019
College of Sciences


Thesis Title
Characterisation of Denitrification in the Subsurface Environment of the Manawatu Catchment, New Zealand

Read article at Massey Research Online: MRO icon

Mitigating the impacts of agriculture on water quality is a critical environmental issue requiring a sound understanding of the transport of nitrate, a key water contaminant, from agricultural lands to waters. However, little is currently known on the losses and potential attenuation of nitrate in the subsurface environment (below the surface soils) of agricultural landscapes, especially in New Zealand. Mr Rivas developed and applied a combination of regional- and local-scale hydrogeochemical surveys and investigations to gain insights into the transport and attenuation of nitrate by subsurface denitrification in the Manawatū catchment. His research revealed low nitrate attenuation potential in shallow groundwaters underneath coarse textured, well-drained soils and highly permeable rocks. In contrast, high attenuation potential was found underneath fine textured, poorly drained soils and low permeability rocks. These new insights are valuable in the formulation of location-specific measures for the effective management of water quality across sensitive agricultural catchments.

Associate Professor Ranvir Singh
Dr Jon Roygard
Professor David Horne