Data set title:
PML Benthic Survey nutrient concentration data from a benthic flux survey experiment at 4 different study sites of Plymouth, South West England, between 2008 and 2011.

Name of data file:
benthic_nutrients_flux_2008-2011.txt

Data set creator(s) and institute(s):
E. Malcolm S. Woodward and Amanda Beesley. Plymouth Marine Laboratory.

Data set period: 
2008-07-11 to 2011-05-19

Data set location:
Cawsand                 50° 19.81' N, 4° 11.50' W
L4                      50° 13.30' N, 4° 11.40' W
Rame                    50° 17.75' N, 4° 16.00' W
Jennycliff              50° 20.91' N, 4° 07.71' W

Data set abstract:
The nutrient samples for the Benthic Flux experiments were taken approximately bi-monthly from different benthic systems that exist near to Plymouth, South West England; these were at L4, Cawsand, Jennycliff and Rame Head sampling sites, and the sampling only occurred when the weather conditions allowed. Results are reported for the analysis of water samples taken from a Benthic Flux Nutrient survey, sampled over a 3 year sampling period between July 2008 and May 2011. The analytical results are reported for Nitrate+Nitrite, Nitrite, Silicate, Phosphate and Ammonium concentrations. These nutrient data will enable calculations to be made for the nutrient fluxes form the sediment cores sampled.

Sampling methodology and description of analytical techniques:
The sediment samples were obtained using a sediment corer from the 4 sampling sites, and there were 8 replicate cores samples taken at each site. The overlying water on the cores was aerated gently and the cores allowed to stabilise for approximately 40 minutes. Nutrient samples were then taken from the overlying water in each core sample, this was T0, and then each core was sampled hourly for a further 5 hours (T1-T5). They were sampled under as clean conditions as possible, using gloves to avoid contamination, and were filtered using a GFF filtering system. The samples were then frozen as soon as possible.
The analyser is a 5-channel Bran and Luebbe segmented flow system using well tested colorimetric analytical methodologies (Woodward, E.M.S, and A.P. Rees, (2001). Nutrient distributions in an anticyclonic eddy in the North East Atlantic Ocean, with reference to nanomolar ammonium concentrations. Deep Sea Research II, 48, Nos. 4-5, 775-794), and the same as those used by the PML Nutrient Facility in all their International Research cruises, and other analytical research programmes. Quality control procedures are carried out with regular use of KANSO certified reference materials for the internal stock standard solutions to be regularly confirmed. The Facility also participates in the European Quasimeme programme as well as being a member of the International Nutrient Scale System International Intercalibration programme steering committee. 

Data quality comments:
The data has all been Quality Controlled, with serious outliers removed where obvious contamination to samples was exhibited. Freezing is not the ideal but with the Benthic Flux samples this was unavoidable and to make some consistency all the samples were frozen so as to gain consistency with the treatment of all the samples. 

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.