Soil water chemistry data from Climoor fieldsite in Clocaenog Forest

Soil solution was sampled below the rooting zone (5 cm depth) by 10 cm x 20 cm polyethylene zero tension lysimeters, installed in each of the plots in autumn 1998. Two lysimeters were installed in each plot and samples were bulked at each sampling interval (bi-weekly) to give a representative sample for the plot. Tensioned soil water samplers (Prenart super quartz, Copenhagen, Denmark) were also installed during autumn 1998, at a depth of approximately 30 cm within the mineral horizon, in each of the plots. Three tensioned soil water samplers were installed per plot, again samples were bulked at each sampling period (biweekly) to give a representative sample for each plot. Samples from both the zero-tension lysimeters and the tensioned soil water samplers were transported to the laboratory within 4 hours of sampling. The samples were filtered through a 45 micrometer cellulose nitrate filter, and stored at 4 degrees C before analysis. pH was measured on a Metrohm 888 Titrando fitted with a 20ml burette and 815 Robotic USB Sample Processor XL (Metrohm, Switzerland). Nitrate (NO3), chloride (Cl), sulphate (SO4) was determined using Dionex DX100 chemically suppressed ion chromatograph using carbonate eluant and AS4a columns (Dionex Corporation, Sunnyvale California 94088-3603 USA). Sub-samples were acidified with 2M HCl and sparged with oxygen to remove any inorganic carbon in the sample before analysis. The remaining non-purgeable organic carbon (assumed to be DOC) was determined with a Shimadzu TOC-V CPH (Shimadzu Corporation, Kyoto, 604-8511, Japan). Ammonium was analysed colormetrically using a SEAL AQ2 discrete analyser. Chemical analysis was carried out in the UKAS accredited labs in CEH Lancaster.