Distribution and assessment of sediment toxicity in Tamaki Estuary,Auckland, New Zealand |
| |
Authors: | G M S Abrahim R J Parker S L Nichol |
| |
Institution: | (1) Department of Geology, University of Auckland, Auckland, New Zealand;(2) School of Geography and Environmental Science, University of Auckland, Auckland, New Zealand |
| |
Abstract: | Heavy metal levels in surface sediments from Tamaki Estuary demonstrate significant up estuary increases in Cu, Pb, Zn, Cd
and mud concentrations. Increased metal levels towards the head of the estuary are linked to local catchment sources reflecting
the historical development, industrialisation and urbanisation of catchment areas surrounding the upper estuary. The relatively
narrow constriction in the middle estuary (Panmure area), makes it susceptible to accumulation of upper estuary pollutants,
since the constriction reduces circulation and extends the time required for fine waterborne sediments in the upper estuary
to exchange with fresh coastal water. As a result fine fraction sediments trapped in the upper estuary facilitate capture
and retention of pollutants at the head of the estuary. The increase in sandy mud poor sediments towards the mouth of the
estuary is associated with generally low metal concentrations. The estuary’s geomorphic shape with a mid estuary constriction,
sediment texture and mineralogy and catchment history are significant factors in understanding the overall spatial distribution
of contaminants in the estuary. Bulk concentration values for Cu, Pb, Zn, and Cd in all the studied surface samples occur
below ANZECC ISQG-H toxicity values. Cd and Cu concentrations are also below the ISQG-L toxicity levels for these elements.
However, Pb and Zn concentrations do exceed the ISQG-L values in some of the surface bulk samples in the upper estuary proximal
to long established sources of catchment pollution. |
| |
Keywords: | Heavy metals Contamination Sediment quality guidelines Geomorphology Tamaki Estuary Auckland New Zealand |
本文献已被 SpringerLink 等数据库收录! |
|