The sampler has now been used in the field for a study in nitrate concentrations. Part of the deployment process included placing the collection bottles in a chilled container, such as a insulated lunch box with ice packs. This adds to the complexity and cost of deployment. However, we needed to be sure that this was required. We then conducted 12 and 24 hour experiments to see if nitrate concentrations deteriorated without being chilled. The 12 hour experiment revealed that we did not need to chill the samples while the sampler was deployed. We are still waiting on the 24 hour experiment results. Nitrate seems to be pretty stable. That is, it is not changing over to N2 or something else too quickly. This would not be the case for studies of other nutrients such as phosphate.
The unit has run as expected. The filter over the pump housing was easily cleaned. The 4,000 mAh battery from Voltaic systems easily ran the system over 24 hours, dropping about 1/4 power during that time. The system could be deployed for up to about 3-4 days at this rate.
Deployment in small brook.
Deployment in an even smaller brook.
Screen over pump housing before cleaning.