Phosphorus in the Mary and vulnerability of storages to algal

blooms

Presentation to the River, the Bay and the Strait Forum

Presenter: Graeme Esslemont (Burnett Mary Regional Group)

Date: Wednesday 5th October 2008

Why I have been asked to speak today?

Cleaner Creeks Cooperative Objectives:

1) Support stakeholders who are seeking voluntary initiatives to improve water quality in local streams (PAP 2).

2) Coordinated provision of reliable training and technical support, and data management (Wide Bay Water Laboratory, Burnett Mary Regional Group).

3) Development of a stakeholder supported dataset at an appropriate scale to identify water quality improvements.

Steering Meeting: Andrew Rickert, Michael Walker (WBWC), Brad Wedlock, Steve Burgess, Glenda Pickersgill, Deb Seal (MRCCC)

Events Monitoring – Events Monitoring – When sediment, When sediment, nutrients & nutrients & herbicides enter the herbicides enter the riverriver

Sediments - Loads

0

200

400

600

800

1000

1200

1400Discharge (cumecs)

TSS (mg/L) at LBTotal Event Discharge (ML) 400,220Number of samples 11TSS Load (Tonnes) 71,660TP Load (Tonnes) 54

FRP Load (Tonnes) 7.6TN Load (Tonnes) 465NO2 Load (Tonnes) 3.5

NOx Load (Tonnes) 171NH3 Load (Tonnes) 30NO3 Load (Tonnes) 167

Tracing P in river sediments for target setting.

Objectives

1) Identify variations of P in river sediments across the region, and identify sections of river with anomalous concentrations of P.

2) Use background ratios to as a guide for target setting, in negotiations with stakeholders for achieving on ground actions.

3) Suggest the application of geochemical ratios for measuring offsite exports of P from farms, to monitor against targets. This might particularly apply to stakeholders who have not embraced hydrological approaches for monitoring loads.

How does P get into sediment?

• Insoluble oxide properties.• Assimilated by living organisms• Included with soil minerals:

– Exchangeable (anion exchange with clays)– iron oxides (e.g. chemical adsorption or inclusion in

gel goethite and other iron minerals)– Organic (e.g. humic acids, particulate organic matter,

iron-reducing bacteria).– Mineral (apatite).

Iron bound PBurnett Mary - Sodium Dithionite (goethite) - P/Fe

y = 0.016x + 3.825

R2 = 0.550

0 200 400 600 800 1000 1200

Fe (mM/g)

P (m M

/g)

Organic bound PBurnett - Aquaregia (organic, apatite)- P/C

y = 0.000x + 3.880

R2 = 0.063

0102030405060708090

100

0 5000 10000 15000 20000 25000

C (mM /g)

P (mM

/g)

Soil Bacteria:

C/N ratio of 17-8 in fungal & bacterial

biomass (Swift et al., 1979)

Redfield C/N in phytoplankton = 6.6 –

7

Fine Particulate Organic Matter = 8 -

267

Carbon/Nitrogen Ratio

y = 14.04x + 0.58

R2 = 0.83

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70

Total Carbon (mM/g)

Tota

l Nitr

ogen

(mM

/g)

The role of carbon in Australian Rivers and Floodplains

Eucalyt carbon

river red gum leaf

0.0

0.1

0.2

0.3

0 20 40 60 80

Days

Cu

mu

lativ

e o

xyg

en

co

nsu

mp

tion

as

mo

les

of

O2

/C

nutrient supplemented nutrient depauperate

Pasture carbon

couch grass

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 20 40 60 80

Days

Cum

ulat

ive

oxyg

en

cons

umpt

ion

as m

oles

of

O2/

C

nutrient supplemented nutrient depauperate

Aquatic plant

Carbon

milfoil

0.0

0.1

0.2

0.3

0.4

0.5

0 20 40 60 80

Days

Cu

mu

lativ

e o

xyg

en

co

nsu

mp

tion

as

mo

les

of

O2

/C

nutrient supplemented nutrient depauperate

Where is Phosphorus enriched in

river sediment?

Soil lossLosing ground ……….. Reduced farm product-ivity

Wetlands can help…

Be aware of over-topping

of fine sediment

and soluble nutrients