Arthur Marble Aquifer and Te Waikoropupu Springs, New Zealand: flow contributions and nitrate sources

Abstract This paper investigates sources of early signs nitrate pollution in a karst aquifer and major spring. Te Waikoropupu Springs are the largest springs New Zealand amongst Southern Hemisphere with mean outflow 13.4 m 3 /s. They discharge clearest water ever recorded from spring, but warning quality deterioration is signalled by increasing concentrations. The partly artesian 2.85 km volume karstified Ordovician marble transmission time averaging 7.9 years. Reservoir porosity unusually high for crystalline carbonate rock, estimated as 6%. Water emerging at Main Spring (9.89 /s) adjacent Fish Creek (3.48 mix recharge four main sources. means mass balance modelling proportions coming each source, origins contamination contribution nitrification. losses into bed upper Takaka River, about 17 Springs, provide 13% flow Spring, 34% 83% discharged submarine springs. Infiltration rain falling over farmed land middle valley to supply 10% total contribute 82% NO -N output Nitrification accounts 16% discharged. A reduction leachate concentration would be required bring values back levels 1970s.