Trace elements and their isotopes are being actively studied as powerful tracers in the modern ocean and as proxies for the palaeocean. Although distributions and fractionations have been reported for stable isotopes of dissolved Fe, Cu, Zn and Cd in the ocean, the data remain limited and only preliminary explanations have been given. Copper is of great interest because it is either essential or toxic to organisms and because its distribution reflects both biological recycling and scavenging. Here we present new isotopic composition data for dissolved Cu (d 65 Cu) in seawater and rainwater. The Cu isotopic composition in surface seawater can be explained by the mixing of rain, river and deep seawater. In deep seawater, d 65 Cu becomes heavier with oceanic circulation because of preferential scavenging of the lighter isotope ( 63 Cu). In addition, we constrain the marine biogeochemical cycling of Cu using a new box model based on Cu concentrations and d 65 Cu.

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Wang et al., 2011 (1) and is converted to δ 97/95 Mo by multiplying 0.67 when the system follows mass-dependent fractionation. Though no commonly-used Mo isotopic standard currently exists (see later), the standards used by different laboratories do appear to be isotopically similar at the level of 0.1-0.2‰. Continental rock samples, such as granite, basalt, and clastic sediments, have δ 98/95 Mo of ~0.1‰ Siebert et al., 2003). Ferromanganese oxides, which scavenge Mo from seawater in oxic conditions, have a light isotopic signature (δ 98/95 Mo = -1.0 to -0.5‰; Siebert et al., 2003), whereas sediments formed in euxinic conditions (aqueous H 2 S concentrations higher than ~11 µM, the action point pro-The molybdenum isotopic composition of the modern ocean (Received September 13, 2011; Accepted January 5, 2012) Natural variations in the isotopic composition of molybdenum (Mo) are showing increasing potential as a tool in geochemistry. Although the ocean is an important reservoir of Mo, data on the isotopic composition of Mo in seawater are scarce. We have recently developed a new method for the precise determination of Mo isotope ratios on the basis of preconcentration using a chelating resin and measurement by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), which allows us to measure every stable Mo isotope . In this study, 172 seawater samples obtained from 9 stations in the Pacific, Atlantic, and Southern Oceans were analyzed, giving global coverage and the first full depth-profiles. The average isotope composition in δ Three-isotope plots for the Mo isotopes were fitted with straight lines whose slopes agreed with theoretical values for mass-dependent isotope fractionation. These results demonstrate that Mo isotopes are both uniformly distributed and follow a mass-dependent fractionation law in the modern oxic ocean. In addition, Mo isotopic analysis revealed that δ 98/95 Mo of the standard used in this study was 0.117 ± 0.009‰ lighter than the Mo standard that was used by Archer and Vance (2008). A common Mo standard is urgently required for the precise comparison of Mo isotopic compositions measured in different laboratories. On the other hand, our results strongly support the possibility of seawater as an international reference material for Mo isotopic composition.

Nerve growth factor (NGF) functions to modulate osteoarthritis (OA)-associated pain. Although recent studies suggest that tumour necrosis factor (TNF)-α and interleukin (IL)-1β mediate NGF activity in human synovial fibroblasts, the regulation of NGF expression in human synovial macrophages remains unclear. Here, we examined the role of macrophages in the production and regulation of synovial (SYN) NGF in osteoarthritic knee joints by examining the mRNA expression of TNF-α and IL-1β in freshly isolated CD14-positive (macrophage-rich fraction) and CD14-negative cells (fibroblast-rich fraction) in synovial tissue from OA patients by quantitative polymerase chain reaction. We also examined the effects of IL-1β and TNF-α on NGF mRNA expression in cultured CD14-positive (macrophage-rich fraction) and CD14-negative cells (fibroblast-rich fraction). In addition, to examine the contribution of macrophages to NGF, TNF-α and IL-1β expression, we injected clodronate liposomes systemically into STR/Ort mice, an osteoarthritis animal model, to deplete macrophages. TNF-α and IL-1β mRNA levels in CD14-positive cells from the SYN of OA patients was significantly higher than that in CD14-negative cells, while NGF expression did not differ markedly between the two cell fractions. In addition, treatment of human cultured CD14-positive and -negative cells with IL-1β and TNF-α enhanced NGF mRNA and protein levels. Expression of NGF, IL-1β and TNF-α was also reduced significantly in STR/Ort mice upon macrophage depletion. These findings suggest that IL-1β and TNF-α regulate NGF expression and production in synovial macrophages and fibroblasts in osteoarthritic joints.

Aluminum (Al), manganese (Mn), cobalt (Co), and lead (Pb) are key trace elements in seawater and thus significant in chemical oceanography research. However, although all of these elements are highly scavenged in the ocean, only a few studies focus on the intercomparison of their distributions. Here, we report the basin-scale and full-depth sectional distributions of these elements observed during three GEOTRACES Japan cruises in the North Pacific. We confirmed that a surface maximum of the dissolved (d) species is not a common feature for the four elements and that the d species have the lowest concentrations in the Pacific Deep Water (PDW) as compared to other oceans. The elements showed different speciations and distributions. The fraction of labile particulate (lp) species was calculated as the difference between the total dissolvable (td) species and d species. The lpM/tdM ratio, where M refers to an element, is highest for Al, at 0.66 ± 0.31 (average ± sd, n = 489), and lowest for Pb, at 0.02 ± 0.08 (n = 575). Further, the distribution of each element is uniquely related to ocean circulation. The tdAl concentration is high in the Equatorial Under Current (EUC), the North Equatorial Current (NEC), and the Lower Circumpolar Deep Water *Manuscript (LCDW). Manganese is supplied from reductive sources such as sediments on the continental shelves around the northern boundary. Cobalt is concentrated in the North Pacific Intermediate Water (NPIW) and in the Equatorial Pacific Intermediate Water (EqPIW) owing to the combined effects of supply from the continental shelves, biogeochemical cycling, and scavenging. Lead shows a subsurface maximum centered at ~35°N and ~200 m depth, implying an association with the formation of the Subtropical Mode Water (SMW) and the Central Mode Water (CMW). Although the subsurface Pb maximum in the Atlantic has diminished over the last three decades owing to the ban on leaded gasoline use, it has been sustained in the North Pacific through the growth of other anthropogenic sources in Asia and Russia. We propose that the enrichment factor of dM, defined as EF(dM) = (dM/dAl) seawater /(M/Al) upper crust , where (M/Al) upper crust is the molar ratio in upper crustal abundance, can be a good parameter for the sources. The median is 1.3  10 2 (n = 436) for EF(dMn), 3.2  10 2 (n = 430) for EF(dCo), and 1.2  10 3 (n = 413) for EF(dPb). The (dPb) found in this study is on the same order of magnitude as the EF values for aerosols found in the literature, suggesting that the deposition of aerosols is a major source for dPb. EFBecause EF(dMn) and EF(dCo) are ten to hundred times higher than the EF for aerosols, sources other than the aerosol deposition are more significant contributors to the concentrations of Mn and Co.

We determined Zn isotope composition (δ 66 Zn) in the water column of the Northwestern Pacific Ocean (NWPO) and its marginal seas to investigate the processes driving vertical and spatial variations. Comparable to previous studies, dissolved δ 66 Zn was relatively low in the top 200 m, ranging from −0.91 to +0.24‰ and increased with depth toward an averaged value, +0.38±0.10‰, in deep water. We found that δ 66 Zn observed in the deep water of the NWPO was much lower than the Northeastern Pacific Ocean. Box model approaches suggest that spatial variations in the deep water may be attributed to isotopically light Zn originating from sedimentary input or anthropogenic aerosols. In the surface water, the fractionation factors derived from both closed or open system fractionation models are all less than one in the NWPO. However, both closed and open system models show a relatively poor fit to the measured data. We thus propose that external input is a major factor causing the variations of [Zn] and δ 66 Zn values in surface water, in addition to the effects of scavenging, physical mixing, and biological uptake. As elevated [Zn] and relatively light δ 66 Zn in the surface water were observed in high aerosol input regions, aerosol deposition may play a dominant role in regulating Zn elemental and isotopic composition in the surface ocean. Key Points: • We observed spatial variations of δ 66 Zn in the deep water of the NWPO and found considerably lighter δ 66 Zn than the NEPO • The sedimentary input may be a major cause of relatively light dissolved δ 66 Zn in the deep water of the NWPO • Aerosol Zn input is a major cause of the variations of [Zn] and δ 66 Zn in the surface water of the NWPO Supporting Information: • Supporting Information S1

We have prepared a large volume of pure, concentrated and homogenous zinc standard solution. This new standard solution is intended to be used as a primary reference standard for the zinc isotope community, and to serve as a replacement for the nearly exhausted current reference standard, the so-called JMC-Lyon Zn. The isotopic composition of this new zinc standard (AA-ETH Zn) has been determined through an inter-laboratory calibration exercise, calibrated against the existing JMC-Lyon standard, as well as the certified Zn reference standard IRMM-3702. The data show that the new standard is isotopically indistinguishable from the IRMM-3702 zinc standard, with a weighted δ66/64Zn value of 0.28 ± 0.02‰ relative to JMC-Lyon. We suggest that this new standard be assigned a δ66/64Zn value of +0.28‰ for reporting of future Zn isotope data, with the rationale that all existing published Zn isotope data are presented relative to the JMC-Lyon standard. Therefore our proposed presentation allows for a direct comparison with all previously published data, and that are directly traceable to a certified reference standard, IRMM-3702 Zn. This standard will be made freely available to all interested labs through contact with the corresponding author