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From page 29... ... 29 3 Seawater NUTRIENTS Measurements of the major elements composing organic matter in ocean environments are among the longest established, most fundamental, and broadly informative analyses in the marine sciences. This tradition is based on the fact that six elements (carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus) Read the entire page →
From page 30... ... 30 CHEMICAL REFERENCE MATERIALS Redfield (1934) , who analyzed the major elemental content of many samples of mixed plankton (phytoplankton and zooplankton) Read the entire page →
From page 31... ... SEAWATER 31 rials ensuring that measurements can be compared at different laboratories over long time periods. The urgent need for nutrient standards was demonstrated during the recently completed World Ocean Circulation Experiment (WOCE) Read the entire page →
From page 32... ... 32 CHEMICAL REFERENCE MATERIALS change over decadal time scales, the observed systematic nutrient differences should represent an estimate of inter-laboratory precision. Offsets were found, however, among the results of different laboratories indicating inconsistencies in the preparation of the calibration standards. Read the entire page →
From page 33... ... SEAWATER 33 standard salinity (approximately 35) should be used as the matrix for nutrient reference materials. Read the entire page →
From page 34... ... 34 CHEMICAL REFERENCE MATERIALS Box 3.1 History of Metal Analysis in Sea Water In the 1960s much of the interest in metals centered on their role as pollutants. Considerable progress was made in characterizing the distribution of bomb-derived radionuclides, but little progress was made for stable metals. Read the entire page →
From page 35... ... SEAWATER 35 Interference in Trace Metal Measurements The major anions and cations in seawater have a significant influence on most analytical protocols used to determine trace metals at low concentrations, so production of reference materials in seawater is absolutely essential. The major ions interfere strongly with metal analysis using graphite furnace atomic absorption spectroscopy (GFAAS) Read the entire page →
From page 36... ... 36 CHEMICAL REFERENCE MATERIALS (DOC) , acidification alone may not be sufficient to render all of a given metal reactive towards the reagents used for analysis. Read the entire page →
From page 37... ... SEAWATER 37 National Science Foundation (NSF) , and the Chemical Oceanography program invests substantial resources in that area. Read the entire page →
From page 38... ... 38 CHEMICAL REFERENCE MATERIALS ticle scavenging, exchange between water masses, and, in some cases, exchange between the ocean and the atmosphere or sediments. Measurements of radionuclides in seawater have been used to study a variety of processes, including ocean mixing, cycling of materials, and carbon flux (by proxy) Read the entire page →
From page 40... ... 40 CHEMICAL REFERENCE MATERIALS water in a coastal pond. These two isotopes have great potential to solve a number of problems in estuarine and coastal oceanography. Read the entire page →
From page 41... ... SEAWATER 41 There are two approaches to providing the missing certified reference materials: 1. prepare additional individual solutions of 210Pb, 210Po, 231Pa, 227Ac, 232Th, and 228Th, or, 2. Read the entire page →
From page 42... ... 42 CHEMICAL REFERENCE MATERIALS concentrations (Lynch-Stieglitz et al., 1995; Mackensen et al., 1996) Read the entire page →
From page 43... ... SEAWATER 43 ning must be used when trying to prepare a seawater-based reference material for 14C in DIC. Read the entire page →
From page 44... ... 44 CHEMICAL REFERENCE MATERIALS 2000) in less than 10 ml of seawater. Read the entire page →
From page 45... ... SEAWATER 45 The stability of the organic components of surface seawater samples is more questionable, but can be tested over time for a wide variety of molecule classes. Although iron samples must be stored in plastic (not glass) Read the entire page →
From page 46... ... 46 CHEMICAL REFERENCE MATERIALS DISSOLVED GASES Atmospheric gases can be divided into those that are relatively constant and those that vary in concentration. The most abundant (and thus relatively constant) Read the entire page →

From page 29...

... 29 3 Seawater NUTRIENTS Measurements of the major elements composing organic matter in ocean environments are among the longest established, most fundamental, and broadly informative analyses in the marine sciences. This tradition is based on the fact that six elements (carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus)