Saliza Mohd Nazri Doctor of Biotechnology Analysis of Jacobs
SKMs benchmark study on effluent emissions from shrimp aquaculture
and sugarcane farms 1
Slide 2
Introduction Jacobs SKM was contracted by QCA to give
independent advice on environmental and technical issues in the
investigation on the regulatory reform of aquaculture in Queensland
[1]. Table 1. Summary of effluent emissions by Jacobs SKM [1].
2
Slide 3
Comparison Table 1. Summary of effluent emissions by Jacobs SKM
[1]. Table 2. The effluent discharge data from prawn aquaculture
farms based on CRC Report 2002 [2] (note: units have been converted
to the same unit used by Jacobs SKM for ease of comparison). 3
Slide 4
Prawn farm effluent data from Jacobs SKM benchmark study 4
Slide 5
Investigation of the value stated in the benchmark study First
row of prawn farm discharges The original study was conducted by
Trott and Alongi [4] but was cited in Burfords [5] review. The
prawn farm pollutant loads did not lead to eutrophication due to
physical and biological processes associated. Examples of the
associated processes : 1)the fast settlements of the nutrients
within the creeks and forests, 2)the efficient flushing and removal
process of sediments during high currents and fluxes, 3)the primary
production undergo grazing by the zooplankton, 4)the consumption of
zooplankton by juvenile fish 5) the effluent discharges were in an
intermittent pattern that permitted the fallowing to take place at
the estuary [4]. 5
Slide 6
Investigation of the highest N value stated in the benchmark
study (prawn farm discharges) Derived from a study done by Jackson
[6] which investigated the effluent loads from three intensive
shrimp farms in Australia. In the study, it was reported that due
to the unusual condition of Farm A, only the discharge values
obtained from Farm B and Farm C should be used as indicator of the
pollutant loads released from intensive shrimp farms [6]. This is
because Farm A used double amount of water (1.36 X 10 6 L ha -1 day
-1 ) as the management changed its main shrimp production species
from P.monodon to M.japonicus in the early of the study and faced
difficulties from the switch. 6
Slide 7
Jackson [6] proposed in the conclusion of his research,
intensive shrimp farms would typically produce 1 kg ha -1 day -1
(365 kg ha -1 yr -1 )of net loads of total nitrogen. In conclusion,
if a correction was to be made in the benchmark study, the 657 kg
ha -1 yr -1 value of nitrogen effluent stated would be replaced
with 365 kg ha -1 yr -1. 7
Slide 8
Sugarcane farm effluent data from Jacobs SKM benchmark study
8
Slide 9
Jacobs SKM referenced a report done by Dr McPhee [7] in the
first row of the benchmark study of the sugarcane farm effluent
data. However, a further investigation into this report by McPhee
revealed that there was also data on the nitrogen emission from
sugarcane farms of 300 kg/ha/yr reported in 1990s (on page 7 of the
report). Hence, there is a big area of improvement needed on the
conclusiveness of the data extracted by Jacobs SKM. If this had
been reported in the benchmark study, the N emission level would be
double than the present data and this would lead to a different
conclusion regarding the relative contributions to effluent loads
in GBR. 9