Data set title:
PML Benthic Survey redox measurements from four sites (Cawsand, L4, Rame and Jennycliff) in the Western English Channel surveyed bimonthly from January 2010 to May 2011.

Name of data file:
benthic_survey_redox_meta_2010-2011.csv
benthic_survey_redox_2010-2011.csv 

Data set creator(s) and institute(s):
Patricia Frickers and Sarah Dashfield, Plymouth Marine Laboratory

Data set period: 
Cawsand                 50° 19.81' N, 4° 11.50' W2010-01-13 to 2011-06-05
L4                      50° 13.30' N, 4° 11.40' W2010-01-14 to 2011-03-16
Rame                    50° 17.75' N, 4° 16.00' W2010-01-25 to 2011-05-11
Jennycliff              50° 20.91' N, 4° 07.71' W2010-01-15 to 2011-05-05

Data set abstract:
Sediment profile measurements of redox potential, Eh (mV), from sub-tidal sites around Plymouth, (Cawsand, L4, Rame and Jennycliff) were determined bimonthly from January 2010 to May 2011. All sites display a high positive Eh at the surface suggesting greater species' affinity for electrons and tendency to be reduced. Generally this positive Eh tends to reduce to zero with increasing depth of sediment to about 10cm when the Eh becomes negative. Below about 10cm depth most profiles display a negative Eh suggesting a low species' affinity for electrons and that the species are at their lowest reduction state or the sediment is subject to anoxic conditions. There are exceptions to these conditions suggesting spatial or temporal variability at individual sites. There are also a number of profiles that suggest an oscillation about the zero axis which could be the result of benthic activity (burrows) introducing oxygen rich water into the sediment to a depth which it would not normally reach thus enabling redox reactions to take place.

Sampling methodology and description of analytical techniques:
Sediment was collected using a boxcorer.  Using acrylic core tubes with a diameter of 6cm, two cores were taken from two separate boxcores.  The depth of the core depended on the depth of the box core,but  the aim was to core down to 20cm.  Eh was measured down the core using a narrow platinum redox electrode at 1 cm intervals.  

Data quality comments:
The author does not have any concerns over the quality of the data set and values are consistent with similar data reported in the wider literature.

Data usage:
It is essential for all users of these data to establish and maintain contact with the nominated current data originators as well as fully consulting the metadata. While not impinging on free data access, this ensures that this dataset is being used in the correct way, and any potential issues with the data are clarified. As more samples are identified, a proper dialogue with these local experts on the series may enable, where appropriate the most recent dataset to be used.