Ballast-Check 2 User’s Manual
4
1
Principles of Operation
1.1 General Approach
Ballast-Check 2 quantifies algae of the 10 – 50 micron size class in ballast water samples as
an indicator to be used for assessing the performance of Ballast Water Treatment Systems
(BWTS) in achieving the IMO/USCG D2 standard.
The instrument is a multiple turnover Pulse Amplitude Modulated (PAM) fluorometer that
provides a rapid, indicative analysis of ballast water samples.
This enables ship operators to quickly assess the risk of exceedance of the D2 discharge
standard for ballast water. Risk of contamination is determined using measurements of the
Abundance and Activity of algae in ballast water.
High Risk:
High Algal Abundance
AND
High Algal Activity
Low Risk:
Low Algal Abundance
OR
Low Algal Activity
This approach is in line with
IMO BWM.2/Circ.42/Rev.1 - 28
th
May 2015. GUIDANCE ON
BALLAST WATER SAMPLING AND ANALYSIS FOR TRIAL USE IN ACCORDANCE WITH
THE BWM CONVENTION AND GUIDELINES (G2)
. Where indicative analysis shows poor
or suspect control, users are advised to confirm performance of the BWTS using more
detailed analysis methods as in the above document.
1.2 Abundance of Algae
Ballast-Check 2 is configured for detecting chlorophyll fluorescence from live algal cells
(i.e.
in vivo
detection of Chlorophyll). Light from the fluorometer is absorbed by algae,
which causes the cell to fluoresce. Fluorescence emitted by the cells is detected,
quantified, and displayed as a digital number estimating the abundance of algae in the
sample. Environmental conditions such as; presence of interfering compounds, cellular
physiology, and light history can influence abundance estimates, the procedure used to
analyze samples on Ballast-Check 2 accounts for most of the interferences, providing an
accurate estimate of algal abundance as cells/ml for 10 – 50 micron sized cells.
1.3 Activity of Algae (Viability)
Ballast-Check 2 uses two LEDs to estimate photosynthetic efficiency. The first LED
(monitoring) is used to excite the sample with very low light intensity so as not to induce a
change in chlorophyll reaction centers. While continuously monitoring the sample using
the monitoring LED, the second LED (saturating) blasts the sample with a high intensity of
light to bring algae to a higher fluorescence state (Fm). The difference between the
monitoring LED's measurement of the maximum (Fm) and minimum (Fo) fluorescence
states is called variable fluorescence (Fv). The ratio (Fv/Fm) is a good measure of the
algal activity, which is measured as a ratio between 0.01 and 0.75.
