Using qualitative backscattered electron (BSE) imaging and quantitative energy dispersive X-ray (EDX) spectroscopy, some investigators have concluded that cement (reversal) lines located at the periphery of secondary osteons are poorly mineralized viscous interfaces with respect to surrounding bone. This conclusion contradicts historical observations of apparent highly mineralized (or collagen-deficient) cement lines in microradiographs. Such conclusions, however, may stem from unrecognized artifacts that can occur during scanning electron microscopy. These include specimen degradation due to high-energy beams and the sampling of electron interaction volumes that extend beyond target locations during EDX analysis. This study used quantitative BSE imaging and EDX analysis, each with relatively lower-energy beams, to test the hypothesis that cement lines are poorly mineralized. Undemineralized adult human femoral diaphyses (n ϭ 8) and radial diaphyses (n ϭ 5) were sectioned transversely, embedded in polymethyl methacrylate, and imaged in a scanning electron microscope for BSE and EDX analyses. Unembedded samples were also evaluated. Additional thin embedded samples were stained and evaluated with light microscopy and correlated BSE imaging. BSE analyses showed the consistent presence of a bright line (higher atomic number) coincident with the classical location and description of the cement line. This may represent relative hypermineralization or, alternatively, collagen deficiency with respect to surrounding bone. EDX analyses of cement lines showed either higher Ca content or equivalent Ca content when compared to distant osteonal and interstitial bone. These data reject the hypothesis that cement lines of secondary osteons are poorly mineralized.

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Dust storms in Asia's interior deserts loft immense quantities of continental crust that are blown over the North Pacific Ocean every year. The transported mineral aerosol is first lofted and then experiences mixing and fallout during the transport. Its elemental signature is no longer that of bulk soil. The concentration for many elements is greater in transported crust compared to bulk soil due to a difference in mineralogy of the small crustal particle. Small particles are defined as those below 100 μm in diameter. The elements Al, Mg, Ca and Na do not experience an internal concentration change with particle size. Many of the elements in the MLO mineral aerosol have concentrations that are greater than 1.5 times that of bulk soil. Iron, an important biological agent, has twice the concentration in the MLO mineral aerosol than in bulk soil. The elemental to Al concentration ratios observed are consistent, implying that the transported crustal material is below 20 μm in diameter.

Aerosol samples were collected at the Mauna Loa Observatory in Hawaii from February 1979 to May 1985. The samples were analyzed via instrumental neutron activation analysis (INAA) for up to 47 elements and via ion chromatography for sulfate. The data are dominated by crustal dust that arrives via long‐range transport from Asia each spring, thus creating a “dust season.” Of the 47 elements detected, 37 have a notably higher mass average during the dust season. The data record is explored using enrichment factors, principal component analysis, and chemical mass balances (receptor modeling). The crustal material accounts for 60–70% of the overall aerosol mass during dust seasons, yet only 15–20% during nondust seasons. It is by far the largest contributor to the natural variation dominating the principal component analysis by describing greater than 60% of the overall variance. Particulate sulfate is another major component accounting for 10–40% of the aerosol mass during dust seasons and 60–75% of the mass during nondust seasons. Particulate sulfate can be derived from crustal material and sea salt. Anthropogenic activity also can produce particulate sulfate or its precursors that can adhere to the surface of crustal material that travels over a polluted area. Minor components in the downslope winds are marine sea‐salt aerosol contributing less than 3% of the aerosol mass during the dust season and 5–6% during the nondust season. Local basalt is considered to contribute less than 2% during the dust season and 3–4% during the nondust season. (Carbon mass is not determined and therefore no carbon‐based aerosols such as soot or organic aerosols are considered in the total aerosol mass.)

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