The November 10 issue of the ScienceDirect “Science of the Total Environment" newsletter contains a paper relating the use of a Teledyne ISCO Water 6712FR refrigerated autosampler for tracking sewage pollution in the Tijuana River Estuary on the U.S.-Mexico border. It's a good read for anyone who tracks pollutants in any source of water and wastewater.
As the paper states, the results are relevant to U.S.-Mexico border communities and other polluted estuaries located anywhere. The 6712FR played a pivotal role in the project. The paper summarizes its use:
Stormwater samples were collected at the Boca Rio site during different hydrologic conditions (Table 1) at hourly time intervals over 24 h periods using a Teledyne ISCO 6700 [actually a 6712] autosampler. Six sampling events were conducted (Table 1) including: 1) dry weather conditions with no cross-border flow (referred to as “dry-no-flow"), 2) dry weather with cross-border flow (referred to as “dry-with-flow"), and 3) during and after a storm event with cross-border flows (referred to as “stormflow"). The estuary receives both spring (semi-diurnal) and neap (mixed semi-diurnal) tides, and the tide types are also listed for each event in Table 1.
The ISCO intake tube was attached to the sonde housing with zip ties and retrieved samples from a depth to the sonde depth. Autosamplers were loaded with autoclaved (at 121 °C for 90 min) 1-L polypropylene (PP) bottles. Ice packs were placed in the interior chamber to chill autosampler bottles and minimize the potential decay of microorganisms and other constituents. As soon as samples could be safely retrieved, autosampler bottles were offloaded, transported to the lab, and immediately analyzed for fecal indicator bacteria (FIB) concentrations and basic water quality parameters (pH, specific conductivity, total suspended solids, and turbidity). For four of the six sampling campaigns, benchtop fluorescence spectra were acquired and dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations were measured. Pre-event and post-event samples and field blanks (consisting of ultrapure water transferred to bottles in the field) were collected in autoclaved 1-L PP bottles as grab samples and immediately transported to the lab for analyses. Sample collection, preservation, storage conditions, and holding times are provided in Supplemental Table S2.
The 6712FR is a sequential or composite refrigerated sampler designed to withstand the harshest indoor or outdoor environments. It features our unequalled "FR" model corrosion-proof refrigerator cabinet molded from polyester resin fiberglass and supported by a stainless steel frame. A UV-resistant gel coat provides a smooth, non-porous finish for added protection and easy cleaning. Thick, foamed-in-place insulation helps keep samples preserved at the EPA-recommended 39°F (4°C). An automatically controlled, built-in heater ensures that samples won't freeze.
The paper is “Evaluation of real-time fluorescence sensors and benchtop fluorescence for tracking and predicting sewage contamination in the Tijuana River Estuary at the US-Mexico border."
