welcome to USGS video training for collecting and processing water quality
data the USGS has a reputation for water data that are reliable and impartial our
data are used by many agencies and scientists to seek to understand and
manage our nation's water resources the water mission area of the USGS has an
important responsibility to collect data that accurately describe the physical
chemical and biological attributes of our nation's water systems to accomplish
this USGS has developed a national field manual for the collection of water
quality data the National Field Manual provides documentation and consistency
in our scientific methods it maintains the accuracy of our data and it sharpens
our technical expertise this video series supplements the National Field
Manual with focused training on selected field techniques
this video presents the types of limitations and operation of turin
splitters the churns are simple to operate easy to clean constructed from
polymer or plastic material and available in an eight liter
at 14 liter sizes
turn splitters or turns are used to combine sub samples as they are
collected from several points in a stream or river the churn is then used
to split the combined water samples into sample bottles that represent the
suspended and dissolve concentrations in the stream or river the advantages
limitations of churns are described in table 2-6 chapter 2 in the National
Field Manual the plastic sharing should be used to process samples for inorganic
analyses polymer Turin can be used for either inorganic or non volatile organic
analyses the original spicket on that plastic churn contains a metal spring
that was found to be a source of metal contamination and must be replaced if
the churn is to be used to process samples for trace element analysis the
spicket can be replaced by the manufacturer with
non contaminating components there are several limitations to terms including
sediment size and concentration the size of the sediment particles cannot exceed
250 microns the total sediment concentration cannot exceed 1,000
milligrams per liter the maximum volume for the 14 litre churned is 13 liters
and the maximum volume for the 8 liter churn is 7 liters after all samples are
withdrawn from the churn the water level inside the churn should be at least 2
inches above the spicket Inlet churns are not approved for some microbiology
sample processing see chapter 7 of the National field manual for additional
details while wearing disposable gloves remove the turn splitter and inner bag
from the turn carrier and place it on a level surface
the dirty hands team member turns a splitter throughout the sample
processing at a uniform rate of nine inches per second by raising and
lowering the disk inside the churn with smooth even strokes when churning the
disk should touch the bottom of the churn on every stroke and his stroke
length should be as long as possible without breaking the water surface for
proper disk alignment insert the disk with the groove made it with the
alignment guide inside the Charmin
before withdrawing any sample pre mix the sample by churning with ten strokes
to uniformly dispersed the suspended material the churning rate should be
about nine inches per second in adequate churning can result in
non-representative samples if the churning rate is significantly greater
than nine inches per second or if the disk breaks the water surface excessive
air is introduced into the sample and that could affect dissolved gases
bicarbonate pH and other sample characteristics do not interrupt the
turning core sub sampling process if an interruption occurs we establish the
turning rate to remix the sample by turning ten strokes at the proper rate
before continuing as the volume of the composite sample in the churned
decreases adjust the stroke length to maintain a churning rate of about nine
inches per second and continue to avoid breaking the water surface within the
churn samples should be withdrawn from the chair in order of volume largest to
smallest empty the churn after all bottles have
been processed if the churn will be reused and filled
disassemble it and clean it on-site all it's still wet as described in National
Field Manual chapter 3 if the churn will not be reused during the field trip
rinse it with DI water before it draws out place it in a plastic bag and in the
churn carrier for transportation back to the office laboratory for
complete the field form and notes to document the type of turn used
for additional information regarding selection cleaning collection processing
and churn splitters see chapters 2 3 4 & 5 of the National Field Manual