Lead North Pacific

Settle, D. M. and Patterson, C. C. (1982). Magnetites and sources of precipitation and dry deposition fluxes of industrial and natural leads to the North Pacific at Enewetak. /. Geophys. Res. 87, 8857-8869. 

Ultraviolet spectroscopy has been applied to the determination of lead and lead speciation studies [407]. Scaule and Patterson [408] used isotope dilution-mass spectrometry to determine the lead profile in the open North Pacific Ocean. 

The O2 content of the surface waters is lower at mid-latitudes because of higher temperatures, which lead to lower gas solubility. As shown in Figure 10.1a, the ther-mocline is characterized by a concentration minimum that increases in intensity from the Atlantic to the North Pacific. Note that the O2 minimum is less pronounced in the vertical profile from 45°S as compared to 9°N in the Atlantic Ocean because of close proximity to the site of AABW formation. Mid-water phosphate and nitrate maxima... 

Capodaglio, G., Coale, K.H. and Bruland, K.W. (1990) Lead speciation in surface waters of the Eastern North Pacific. Mar. Chem. 29, 221-233. 

For example, an extensive 9-year data set from ALOFLA indicates that the bulk dissolved matter N P ratio is variable. In the subtropical North Pacific Ocean, N2 fixation may supply up to half of the new N to sustain the rate of the annual particulate N export from the euphoric zone. A recent increase in this source of new N appears to have shifted the North Pacific subtropical gyre from N Hmitation to P hmitation (Karl et al., 1997). Hence in the ohgotrophic ocean, N2 fixation could lead to a decoupling of N and P pool dynamics and an alternation of N versus P control of primary production (Karl et al., 2001). Similarly but on a shorter time-frame, in the central Baltic Sea the development of N2-fixing cyanobacterial blooms can drive the system from N limitation to P hmitation between May to September (Nausch et al., 2004). 

The ocean has received far less attention than wetlands and soils as a source and sink of CH4. Studies of CH4 distributions in the Eastern Tropical North Pacific showed two CH4 maxima (Rurke et al., 1983) a surface maximum presumably associated with methanogensesis in fecal fellets (Karl and Tilbrook, 1994) and a deeper maximum. The mass spectrometric GC/C/IRMS technique discussed earlier allows measurement of fi CEU in small samples of seawater (Holmes et al., 2000). This technique was applied in the Eastern Tropical North Pacific (Sansone et al., 2001) to study methanogenesis and methane oxidation. The Sansone et al. (2001) results show a distinct difference in the fi CEU from the two CH4 maxima, leading to the suggestion that the deeper maximum may result from long distance offshore transport of CH4 with a shelf or seep source similar to that shown in Cynar and Yayanos (1993, figure 3). 

Figure 8 Vertical profiles of dissolved lead in the central North Atlantic (34° 15 N, 66° 17 W data from Schaule and Patterson, 1983), the central North Pacific (32°41 N, 145°W data from Schaule and Patterson, 1981), and the central South Pacific (20°S, 160°W source Regal and Patterson, 1983). Estimates of the atmospheric input at the time of sampling and in ancient times prior to the large anthropogenic lead input are also shown (Flegal and...

On the other hand, a nutrient-type trace metal like Zn attains a concentration of dissolved Zn that is approximately five times greater in the old, nutrient-rich deep waters of the North Pacific than they are in the young, nutrient-poor North Atlantic deep waters. Its distribution in both ocean basins is similar to that of silicic acid. The efficiency with which Zn is recycled in the ocean leads to its relatively long oceanic residence time. 

Lee DS, Edmond JM and Bruland KW (1985/86) Bismuth in the Atlantic and North Pacific a natural analogue to plutonium and lead Earth Planet Sd Lett 76 254-262. 

In the North Pacific, measurements of dissolved lead in the surface waters revealed that 50% was organically complexed by one class of strong organic ligands found to have concentrations between 0.2 and 0.5nmol 1 . The free Pb surface water concentration as a result of inorganic and organic complexation was 0.4 x 10 mol 1 . ... 

Decreasing concentrations of Pb in surface waters of the Atlantic Ocean have been documented by observations from 1979 until the present (Figure 3). The decreasing concentration of Pb in the upper layers of the ocean is also observed (Figure 4), with a slower response in the deeper waters that are replaced on decadal timescales. These decreases are seen in other parts of the Atlantic and North Pacific as well. This evidence amply demonstrates that the phasing out of leaded gasoline in the USA has been closely followed by decreases of the Pb concentration of the ocean on the appropriate timescale. 

Figure 3 A comparison of the calculated fluxes of aluminum (Al), iron (Fe), thorium (Th), vanadium (V), copper (Cu), zinc (Zn), selenium (Se), and lead (Pb) (in 10 g cm year" ) from the atmosphere to the ocean and from the ocean to the sediments in the central tropical North Pacific. For each metal note the relative similarity in the two fluxes, except for lead and selenium. (Reproduced with permission from Duce, 1998.)...

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