Transcript Analysis of Phosphorus forms in Waiteti Stream sediments

Analysis of Phosphorus forms in
Waiteti Stream sediments
Jamie Peryer-Fursdon
BOPRC Summer Student 2012/2013
Study Aims:
• To look at stream sediment composition and
its potential effects on lake degradation
• Compare stream sediment’s with Dylan
Clarke’s detainment bund sediments
• Specifically look at forms of Phosphorus
Sample Sites
Detainment Bund
Stream sediment
sample
Stream sample collection:
-Sediment Corer, or
-Sediment (Ponar) Grab
Methods
Using chemical analyses to see what
elements the P is bound to:
• either strongly bound- Ca/Al bound
•bound to redox sensitive elements-Fe/Mn
(potentially bio-available)
Also equilibrium P concentration (EPC) of
sediments
mg P (kg dw) -1
P Concentrations
4000
3000
2000
1000
0
Waiteti
DB
Graph: D. Clarke
Hauraki Awahou L. Rotorua Lake
DB
DB
bed (0- Rotorua
2cm)
bed (02cm)
•Stream sediments have much lower
concentrations of P than other sources
Waiteti
Stream
bed
(2012)
500
450
R² = 0.593
400
TP (mg P/kg d.w.)
350
300
250
200
150
100
50
0
0
2000
4000
6000
8000
10000
12000
Dist from mouth (m)
• Generally more phosphorus in upper
catchment stream sediment
14000
16000
Potential Bio-availability
100%
Proportion of three sequentially extracted fractions
90%
80%
70%
60%
HCl-P
50%
NaOH-P
BD-P
40%
30%
Fe/Mn bound P
Could be released
when deposited in
lake sediment
20%
10%
0%
Stream (n=8)
Bunds (n=4)
Equlibrium P Concentrations
SITE
1
9
Wai DB
Mean DRP 20022009 Waiteti Strm
EPC (mg/L)
0.025
0.022
0.140
0.042
• Stream sediments lower EPC than overlying
water
• Bund sediments much higher EPC than stream
water therefore net desorption of P into water
contributing to DRP
Stream Sediment
• Low overall concentration
• Around 30% of P can potentially add to
internal loading when deposited into
lake.
• Could be a P sink for overlying water in
stream conditions
DB sediment
• Higher potential downstream effects from this
sediment
• Initially net desorption of P from sediment
into water-bio available
• Around 25 % of P still bound to sediment can
be released when settled in lake sediments
• Hence importance of DBs within lake
catchment
Photo: D. Clarke
Acknowledgements:
Special Thanks to:
Land Owners:
Elizabeth Hosking, John Coatesworth, Mike & Rebecca
Pethybridge , Murray Scott, T & M Cairns
Supervisors:
Dr Jonathan Abell, Dylan Clarke, Prof David Hamilton, Alastair
MacCormick
Others:
Dr Deniz Özkundakci, Annie Barker, Steve Cameron, Michael
Hupfer, Annette Rodgers
Bay of Plenty Regional Council for this opportunity