Nutrients from HOT cruises 127 through 166 Fernando Santiago-Mandujano 3 November 2006 Samples of Inorganic nutrients until cruise HOT-126 were measured at the University of Hawaii by Ted Walsh. Due to medical reasons Mr. Walsh was not able to continue measuring samples from subsequent cruises. Other analysts continued with the measurements after a long period of time during which the measuring techniques were tested to ensure continuity in the quality of the measurements. During this period samples from cruises were being stored, and after measuring them some of the samples had unreliable values which had to be flagged as bad or suspect. Below is an update of the measurements made up to cruise 159. The rest of the samples up to cruise 166 were finalized and quality controlled by November 2006. Update of inorganic nutrient measurements HOT-127 through 159 Fernando Santiago-Mandujano 7 July 2004 Summary Samples taken during HOT cruises since HOT-127 for inorganic nutrient measurements are being measured by Evgeny Dafner (with the assistance of Daniel Fitzgerald until April 2004). Deep Silicate measurements from non-frozen samples have been measured and quality controlled for all HOT-127 through 159 cruises, and the results are within expected values. Nitrate and Phosphate from non-frozen samples were also measured, but these results were unreliable, however enough sample is still available for more measurements. After implementing and testing the techniques for low-level nutrient measurements, Evgeny measured the samples from HOT-158 and 159 including frozen and non-frozen samples. These measurements were done using a new Autoanalizer. All measurements including the Nitrate and Phosphate measurements of non-frozen samples were within acceptable values (except for some deep phosphates from HOT-158). Now that the nutrient measurement techniques are implemented and seem to be reliable, Evgeny will continue measuring the remaining backlog of nutrient data (Silicate, Nitrate, and Phosphate from frozen samples; and Nitrate and Phosphate from non-frozen samples) strarting with HOT-157 and going backwards until HOT-127. Evegeny estimates that it will take him about 1.5 weeks to measure each cruise's data. Non-frozen samples Silicates Silicates were measured from non-frozen samples from cruises HOT-127 through 153 and were available for quality control in December, 2003. Measurements for HOT-154 through 158 were available in April 2004. Measurements from HOT-159 were available in June. The attached plots include these data plotted together with historical data. The following Silicate data have been flagged: Cruise Station Cast Bottle Flag (4:bad, 3:suspect) 127 2 1 16 3 128 2 1 3 3 128 2 1 5 3 132 2 1 10 3 136 2 2 16 3 136 2 2 17 3 137 2 1 13 3 137 2 1 14 3 141 2 1 14 3 142 2 1 14 3 149 2 1 17 3 150 2 1 14 3 152 2 1 14 3 156 2 1 1 4 Nitrate and Phosphate Nitrate and Phosphate data from cruises HOT-127 through 153 were measured in December 2003, and quality controlled. The Nitrate data had an overall trend towards low values, and the Phosphate data were not reliable. The non-frozen samples from these cruises still have sufficient volume available for more measurements. Recent measurements with new Autoanalizer HOT-158 samples Methods for low-level nutrient measurements were implemented and tested by Evgeny using a new Autoanalizer, and samples from HOT-158 were measured and were available in June 2004 (plots included). These measurements also included Nitrate and Phosphate from non-frozen samples. Quality control indicated that all nutrient values were within acceptable values, with the exception of some deep Phosphate values from the deep cast (Station 2, cast 1). These samples were re-measured two more times to check for possible operational errors, and the results were consistently lower than the historical data. These data were flagged suspect. In addition, near-surface Silicate data appear to have lower values than the historical data. Evgeny explained that these measurements are correct, and the difference is due to the fact that the new Autoanalizer is more sensitive than the one used for previous measurements. The following data were flagged from HOT-158. Variable Station Cast Bottle Flag (4:bad, 3:suspect) Silicate 2 1 10 3 Nitrate 2 1 12 4 Phosphate 1 1 1 4 Phosphate 2 2 4 3 Phosphate 2 1 1-13 3 HOT-159 samples. Nutrient measurements from HOT-159 were available in June, 2004, and were quality controlled (plots included). All nutrient values from this cruise (including deep Phosphates) were within the values of the historical data (with the exception of the near-surface Silicates, as explained for HOT-158). The following data were flagged from HOT-159. Variable Station Cast Bottle Flag (4:bad, 3:suspect) Silicate 2 1 14 3 Silicate 2 1 16 3 Nitrate 2 1 15 3 Nitrate 2 1 2 3 Nitrate 2 1 8 3 Nitrate 2 1 11 3