New Zealand Journal of Marine and Freshwater Research abstracts
Water quality and sediment and nutrient export from New Zealand hill-land catchments of contrasting land use
John M. Quinn
Morag J. Stroud
National Institute of Water and Atmospheric
Research Limited
P.O. Box 11 115
Hamilton, New Zealand
email: j.quinn@niwa.cri.nz
Abstract Measurements were made of suspended sediment (SS), volatile suspended solids, dissolved organic carbon (DOC), nitrogen (N) and phosphorus (P) concentrations, turbidity, black disk visibility, pH, alkalinity, and temperature, at monthly intervals for 2–5 years on nine streams draining catchments with pasture, pine plantation, and native forest land uses. Stream flow and flow-weighted concentrations of SS, N, and P were also measured for up to 2 years from pasture, native forest, and mixed land-use catchments enabling calculation of export (kg ha–1 yr–1). During 1996–97, export from the pasture stream was 2.5- to 7-fold higher for SS (988), total P (1.50), total Kjeldahl N (5.65), nitrate N (4.37), and ammoniacal N (0.34) than from the stream draining native forest. In contrast, export of DOC (25.5) and dissolved reactive P (DRP) (0.25) from the pasture stream were within 20% of the native stream’s values. Export of SS and nutrients (except DRP) from the pasture catchment was 4- to 15-fold higher during the winters of 1995 and 1996 than winter 1997 when rainfall was half the normal level. Streams draining native forest had lower temperature, sediment, and nutrient concentrations (except DRP), and higher water clarity, than those draining pine forest and pasture. A pine/scrub stream had the highest SS and turbidity and lowest DRP, pH, and alkalinity. Pasture streams had the highest concentrations of all N species (geometric means 2- to 4-fold > native), total P, and DOC, and also showed the greatest variation in water quality attributes in relation to season and flow. The influences of land use were attributable to differences in both source materials of sediment and nutrients available for transport and changes in rates of in-stream processing.
Keywords agriculture; plantation forestry; native forest; phosphorus; nitrate; nitrogen; dissolved organic carbon; pH; alkalinity; erosion; sediment; stream flow; temperature
M01031 Received 19 April 2001; accepted 13 September 2001
New Zealand Journal of Marine and Freshwater Research, 2002, Vol. 36: 409–429
0028–8330/02/3602–0409 $7.00 © The Royal Society of New Zealand 2002
PDF file of entire paper: Print-quality (607K)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
