More than 350 samples from Site 1171 ranging in depth from 0.4 to 937 meters below seafloor (mbsf) were analyzed for P and a suite of metals (Fe, Al, Ti, and Ba) at a sample resolution of three per core by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Bulk samples were dried, crushed, and stored in glass scintillation vials.
Approximately 0.2 g of each carbonate-rich sample (>90 wt%) and 0.1 g of all other samples were dissolved using a CEM Corp. MDS 2000 microwave digestion system with concentrated trace-metal grade HNO3, HF, and HCl following Environmental Protection Agency SW846 Method 3052, with the modification that carbonate-rich samples were digested using 1 mL (instead of 4 mL) of HF in order to prevent the precipitation of synthetic fluorite. Once the digestion was complete, 0.2 g of boric acid was added to stabilize the solutions. Samples were transferred to new 50-mL polyethylene centrifuge tubes and diluted to 50 mL with Milli-Q water. A Leeman Labs P950 ICP-AES with a CETAC Corp. AT 5000+ ultrasonic nebulizer was used to determine the total elemental concentrations. All elemental data are presented in Table T1. Ten percent of the samples were analyzed as randomly chosen replicates, which agreed within 6% for all elements analyzed. Details of replicate precision, relative error, and instrumental detection limits are listed in Table T2. Detection limits were calculated as three times the standard deviation of the blank value. Two internal consistency standards were created by homogenizing samples from different depths and different cores rather than standard reference materials. The internal consistency standards were used in order to matrix match samples with consistency standards in terms of acid concentrations and sediment lithology. The first standard was created from carbonate-rich samples, and the second was created from the siliciclastic samples of Eocene or older age. The digested standards were analyzed throughout the analyses to ensure digestions were complete and to ensure accuracy. The standards agreed within 5% for all elements analyzed.