Ballast Water Sampling and Sample Analysis for Compliance Control - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 216

water-column sampler, and a bottom and sediment sampler. Tests on board of
commercial vessels have shown that this sampling equipment can successfully be
used to sample most organisms despite some size limitations which may occur for
large organisms due to the opening dimension of the sampling tool. The suitability
tests also confi rmed that all three water samplers considered can be safely used on
almost all ships, while not disturbing normal ship operations conducted in the port.
In addition to their deployment via sounding pipes these especially designed sam-
plers can also be employed via manholes or tank hatches.
In-tank sampling may be more appropriate for scientifi c research and risk assess-
ment analysis with the aim to assess ballast water biota, while at discharge sampling
is more appropriate for the compliance monitoring with BWM requirements (e.g.,
the D-2 standard). However, certain tanks are not discharged through pipework on
board, but may use gravity for emptying. In those cases in-tank sampling is the only
approach to prove compliance with BWM standards. Further, in-tank sampling may
also be used to confi rm risk assessment results, e.g., to proof the presence or absence
of target organisms before the ballast water is being discharged.
Sounding pipe sampling for zooplankton does not result in a representative sam-
ple of species in the tank as comparisons of sounding pipe and manhole samples
from the identical tank showed that net samples were more diverse. Sounding pipe
samples contained 0-60 % of the organisms of a net sample which highlights the
need to sample ballast tanks via opened manholes. Further, pumps used via open
manholes delivered more diverse samples compared to plankton net samples, so that
pumps may also be considered when sampling via manholes.
In summary, future ballast water studies should consider that sampling via
sounding pipes is inferior when selecting appropriate sampling techniques. However,
in many occasions manholes cannot be opened due to overlaying cargo or cargo
operations in the area where the manhole is located so that it is unsafe for sampling
work. In these instances sounding pipe sampling might be the only possible option
to sample the ballast water at all.
If the sampling has to document non-compliance, i.e., violations of the ballast
water discharge standard, much less onerous sampling requirements are posed to
the port State to demonstrate that an explicit organism concentration value is
exceeded. For example, should a sample from the tank contain 1,000 viable organ-
isms greater than or equal to 50

m in minimum dimension and the tank capacity is
100 cubic metres, the organism concentration would exceed the D-2 standard when
the water is discharged.

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Recommendations

Several different ballast water sampling methods and equipments have been used
for different sampling purposes. Shipboard sampling is also conducted for BWMS
performance testing for type approval. Hence, shipboard sampling methods for test-
ing BWMS exist, and these have been approved by different national responsible