Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

Sediments of Pauatahanui Inlet: nutrient status and role in water quality. Technical Report

Smith, A.P.D., McColl, R.H.S.
Journal / Source
New Zealand Department of Scientific and Industrial Research Soil Bureau Scientific Report
52 pp.
Sediments, nutrients, water quality, intertidal, Pauatahanui Inlet
Study on the effects of sediments on water quality as part of the PEP providing baseline information. In the upper 1cm of intertidal sediments, concentrations of total nitrogen and organic carbon were about l0x less than, and the total phosphorous about half those of the catchment topsoils. Concentrations of the 3 elements increased highly significantly with “mud” (clay + silt) content and, in the case of nitrogen and phosphorous, with decreasing depth in the sediment profile. Nutrient levels in intertidal sediments near the mouths of the inlet’s northern and eastern shores (draining richest agricultural areas) were 2x those on southern shores. During two rain storms, the concentration of suspended matter leaving the inlet at Paremata gradually declined in 3 days. This indicates fairly rapid settlement and efficient tidal flushing of stream-borne material.
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